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[Display omitted] • Novel ultrasmall organosilica nanoparticles (ONs) were synthesized by a one-step hydrothermal method. • Ultrasmall ONs with avoiding aggregation-induced quenching effect exhibit strong solid-state orange fluorescence. • Ultrasmall ONs can be used in fingerprints detection, white light-emitting diodes, and fluorescence imaging of lysosomes. Organosilica nanoparticles (ONs), which are a new type of photoluminescent nanomaterial (PM) with excellent biocompatibility, have caught more attention in recent years. However, their applications are significantly impeded by the complicated preparation process, poor photostability, and especially aggregation-induced quenching. The present study was aimed to design and prepare solid-state fluorescent ONs to avoid aggregation-induced quenching effect. In addition, the uses of ONs for fingerprint detection, white light-emitting diodes (WLEDs) and lysosome-targetable cellular imaging were demonstrated. Here, for the first time, we designed and prepared novel solid-state fluorescent ultrasmall ONs with orange-emitting photoluminescence via a one-step hydrothermal method. The prepared solid-state fluorescent ONs could be successfully employed in fingerprint detection, WLEDs fabrication and cellular imaging. Intriguingly, the ultrasmall ONs specifically localized to lysosomes rather than other subcellular organelles across distinct cell lines, including cancer cells and noncancerous cells. Collectively, these data showed that the new ONs presented in this study could be ideal candidates for PMs in biological and photoelectric applications. [ABSTRACT FROM AUTHOR]

Compared with visible fluorescence carbon dots (CDs), the multi-emission (visible and near infrared) fluorescence CDs based platform (V-N Platform) with blood-brain barrier penetration, real-time brain imaging and drug loading capacities, is of great significance. Herein, a novel type of multi-emission fluorescence CDs (GT) was created to penetrate BBB for brain imaging and local drug delivery, which was synthesized by hydrothermal method, using endogenous l -tryptophan and d -glucose. The capability for in vitro imaging was verified through the experiments on cell imaging. Moreover, the ability of in vivo imaging, especially for brain imaging, was confirmed by experiments in mice and zebrafish. In addition, the in vitro and in vivo experiments preliminarily confirmed its potential to act as a drug delivery platform. This V-N Platform (GT) will be expected to have a significant impact on the researches for CDs and the theranostics of brain diseases. A novel kind of multi-emission fluorescence carbon dots (GT) was created with NIR fluorescence to act as the "V-N Platform", using endogenous nutrients. With the BBB-penetrating ability and drug loading potential, GT could be expected to with the potential of theranostics for brain diseases. [Display omitted] • GT CDs was synthesized using two endogenous nutrients (d -glucose and l -tryptophan) as the precursor by hydrothermal method. • The retained bio-activity of d -glucose and l -tryptophan enabled GT to cross the BBB effectively. • Carbonization endowed GT with multi-emission fluorescence, especially the NIR fluorescence. • GT could be used as fluorescent probe at multi-level,especially the brain imaging in real-time. • Nanoscale ensured GT as a drug carrier for loading drugs with various polarity. [ABSTRACT FROM AUTHOR]

Fluorescence lifetimes and quantum yields featuring polycyclic aromatic hydrocarbons (PAHs) and other organics constituting pyrogenic carbon particulate matter (PM) are seldom measured. In this work, PM sampled in a fuel-rich ethylene flame was firstly separated in organic carbon (OC), soluble in dichloromethane, and refractory organic carbon (ROC), soluble in N -methyl pyrrolidinone, and then analyzed by size exclusion chromatography (SEC) coupled with online UV and fluorescence detection, and by offline fluorescence spectroscopy and mass spectrometry. It was found that three classes of differently light emitting carbon dots (CDs) could be bottom-up synthesized in the same flame system by selecting appropriately the residence time. Actually, OC presented blue fluorescence regardless the residence time, whereas ROC sampled at low and high residence time emitted fluorescence in the green (green CDs) and in the yellow (yellow CDs) region, respectively. The SEC molecular weight of all CDs presented similar trimodal distributions, centered around 300, 1000 and 10,000 u. For the first time fluorescence lifetimes and quantum yields of pyrogenic CD fractions were measured as additional parameters useful for discriminating the fluorescent components and inferring their structural properties, with the support of mass spectrometry. The different spectroscopic features of CDs could be associated to different compositional characteristics as the polydispersity of molecular components featuring blue CDs, opposed to the oligomer-like nature of green and yellow CDs. Pyrogenic CDs showed different fluorescence emission ranges, quantum yield and lifetimes, appealing for their possible applications in the fields of imaging, electronics and sensors. [Display omitted] [ABSTRACT FROM AUTHOR]

Mitochondrial viscosity and mitochondrial membrane potential (MMP) are vital parameters for reflecting mitochondrial conditions and they are closely correlative in various biological events. Accordingly, simultaneous detection of mitochondrial viscosity and MMP is imperative for elucidating their interactions, further exploring the mechanism of diseases, and investigating numerous pathological procedures. However, such profound research remains a big challenge due to the lack of high-performing single fluorescent probes capable of simultaneously visualizing of these two parameters. In this study, we developed a new kind of fluorescent carbon dots (CDs) that can successfully realize simultaneous monitoring of mitochondrial viscosity and MMP in living cells. The fluorescence of CDs can be specifically turned on as the viscosity of solvents increases from 0.89 to 945 cP. Meanwhile, the CDs accumulate in mitochondria under normal MMP conditions, switch to exist in both mitochondria and nucleoli under reduced MMP, and present only in nucleoli with the vanishment of MMP. Thus, various MMP situations can be easily differentiated through the changed spatial distributions of CDs. More importantly, based on the developed CDs, an increased mitochondrial viscosity accompanying a decreased MMP was simultaneously tracked in drug-stimulated cells. We envision that the developed CDs has a great potential to be utilized as a promising fluorescent probe for mitochondrion-related biology studies. The carbon dots were elaborately designed for simultaneous determination of mitochondrial viscosity and membrane potential through their fluorescence variation and location migration from mitochondria to nucleoli. [Display omitted] • The fluorescence of Carbon Dots (CDs) was specifically turned on as the viscosity of solvents increased. • Fluctuation of mitochondrial membrane potential was visualized through migration of CDs from mitochondria to nucleoli. • An increased mitochondrial viscosity accompanying a decreased membrane potential was simultaneously monitored in cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • We have developed a novel quercetin (a SARS-CoV-2 inhibitor) coupled benzyl ethers (QBE) chemosensor for selective detection of Hg2+. • To date, there are very few reports where quercetin itself have been used in sensing field (table 1) but the use of quercetin derivative in sensing field is almost nil. • To the best of our knowledge our chemosensor QBE is the first chemosensor based on quercetin derivative for the selective detection of Hg2+. • The binding phenomenon of QBE with Hg2+ has been proved by UV–vis, fluorescence, DFT and cyclic voltammograms study. • Lower LOD (Limit of Detection) at 8.47 µM and high binding constant value as 2 × 104 M−1 showed the strong binding affinity of Hg2+ towards QBE. • The intracellular activity of QBE with Hg2+ binding has been examined by using living plant tissue by using green gram seeds. Quercetin is an important antioxidant with high bioactivity and it has been used as SARS-CoV-2 inhibitor significantly. Quercetin, one of the most abundant flavonoids in nature, has been in the spot of numerous experimental and theoretical studies in the past decade due to its great biological and medicinal importance. But there have been limited instances of employing quercetin and its derivatives as a fluorescent framework for specific detection of various cations and anions in the chemosensing field. Therefore, we have developed a novel chemosensor based on q uercetin coupled b enzyl e thers (QBE) for selective detection of Hg2+ with "naked-eye" colorimetric and "turn-on" fluorometric response. Initially QBE itself exhibited very weak fluorescence with low quantum yield (Φ = 0.009) due to operating photoinduced electron transfer (PET) and inhibition of excited state intramolecular proton transfer (ESIPT) as well as intramolecular charge transfer (ICT) within the molecule. But in presence of Hg2+, QBE showed a sharp increase in fluorescence intensity by 18-fold at wavelength 444 nm with high quantum yield (Φ = 0.159) for the chelation-enhanced fluorescence (CHEF) with coordination of Hg2+, which hampers PET within the molecule. The strong binding affinity of QBE towards Hg2+ has been proved by lower detection limit at 8.47 µM and high binding constant value as 2 × 104 M−1. The binding mechanism has been verified by DFT study, Cyclic voltammograms and Jobs plot analysis. For the practical application, the binding selectivity of QBE with Hg2+ has been capitalized in physiological medium to detect intracellular Hg2+ levels in living plant tissue by using green gram seeds. Thus, employing QBE as a fluorescent chemosensor for the specific identification of Hg2+ will pave the way for a novel approach to simplifying the creation of various chemosensors based on quercetin backbone for the precise detection of various biologically significant analytes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A dual-locked fluorescence probe (TPA-DNP) for LDs and HClO was designed. • TPA-DNP could detect LDs and HClO simultaneously by "turn-on" fluorescence singal. • TPA-DNP had successfully been applied in imaging HClO within LDs accumulation environments. • The real-time dynamic imaging of LDs and HClO by TPA-DNP under the LPS-induced inflammatory system. Inflammation is a key factor leading to the occurrence and development of many diseases, both lipid droplets (LDs) and hypochlorous acid (HClO/ClO-) are regarded as the important biomarkers of inflammation. Therefore, it is of great significance to develop an efficient single chemical sensor that can simultaneously detect these two biomarkers. To achieve the goal, we developed a dual-locked fluorescence probe (TPA-DNP) by fusing two targets activated reporting system, its implementation was achieved by turning-on the fluorescence of TPA-DNP through LDs and HClO/ClO- simultaneously. In simulated LDs environment, TPA-DNP displayed excellent selectivity to HClO/ClO-, high sensitivity (LOD = 0.527 μM) and strong anti-interference ability. In addition, cell and zebrafish imaging experiments showed that TPA-DNP could be utilized to visualize exogenous/endogenous HClO/ClO- in LDs environment, and could also be used to observe the impact of LDs changes on the HClO/ClO- detection. On the basis, TPA-DNP served as a favorable tool to achieve visualization of inflammatory dynamic changes. [ABSTRACT FROM AUTHOR]

• Constructing a complex (1) with precise structures by introducing luminescent groups triphenylphosphine (TPA), is used for treatment and imaging. • Within 0.5 h, 1 can be distributed into cells, performing effective cell imaging. • 1 can be used for CDT, promoting oxidative stress and causing cell apoptosis. The combination of imaging and treatment is the fundamental strategy for achieving precise anticancer treatment. This article constructs a copper(I) complex (1) by aminourea derivative containing triphenylamine (TPA). 1 with precise structure, can be used for cell imaging and chemodynamic therapy (CDT). Within 0.5 h, 1 can be distributed into the mitochondria of T24 cells, performing effective cell imaging and then promoting oxidative stress and causing cell apoptosis. A precise complex with luminescent triphenylphosphine (TPA) group, is used for the effective cell imaging, promoting oxidative stress and causing cell apoptosis. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The probe P-1 can selectively detect H 2 O 2 with colorimetric change. • the P-1 can be used for on-site and visual detection of H 2 O 2. • The P-1 can image H 2 O 2 in cells and distinguish cancer cells and normal cells. • The P-1 probe was applied to monitor H 2 O 2 of tumor in mice. We designed and developed the probe P-1 for detecting H 2 O 2. The probe can selectively detect H 2 O 2 with colorimetric change. In addition, the combination of portable test strips with a smartphone platform provided great convenience for on-site and visual detection of H 2 O 2 with satisfactory sensitivity and reliability. The P-1 can image exogenous and endogenous H 2 O 2 in cells and distinguish cancer cells and normal cells by fluorescence image of H 2 O 2 and flow cytometry. Meanwhile, the P-1 probe has been successfully applied to monitor H 2 O 2 levels of tumor in mice, and the results showed the level of H 2 O 2 in tumor tissue increased significantly. Therefore, P-1 provided a potential chemical tool to understand pathological and physiological mechanisms of diseases by imaging H 2 O 2. [ABSTRACT FROM AUTHOR]

The in situ precise quantification and simultaneous imaging of low abundance microRNAs (miRNAs) within living cells is critical for cancer diagnosis, yet it remains a significant challenge. Leveraging the excellent sensitivity and spatiotemporal resolution of dark-field microscopy (DFM) and fluorescence imaging, we have successfully devised a novel detection approach using dual-signal reporter probes (DSRPs). These probes allow for highly sensitive detection of miRNA-21 in living cells via toehold-mediated strand displacement cascades. The DSRPs were constructed by Au nanoparticles and Ag nanoclusters core-satellite nanostructures. After the recognition of miRNA-21, the strand displacement cascades were triggered, inducing the disassembly of the Au/Ag core-satellite nanostructure with apparent scattering intensity decrease and peak wavelength shifts. Additionally, the fluorescence of Ag clusters could be recovered and further enhanced when in close proximity to specific guanine-rich strands. The dual-signal response capability enables the accurate detection of miRNA-21 from 1 fM to 1 nM, with a limit of detection reached 0.75 fM. DFM and fluorescent imaging of living cells efficiently confirms the applicable detection of miRNA-21 in complex detection media. The biosensor based on DSRPs represents a promising nanoplatform for visual monitoring and imaging of biomolecules in living cells, even at the single particle level. [Display omitted] • Dual-signal reporter probes was proposed based on core-satellite nanostructures. • Target microRNA triggered the strand displacement cascades on the probe surface. • The dual signals of LSPR shifts and fluorescence enhancement were induced. • Accurate detection and simultaneous imaging of intracellular microRNA were realized. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two rhodamine derivatives (L-Et and L-Pr) were developed without imine bond to avoid hydrolysis for Al3+ sensing with high selectivity. • There were significant increments in fluorescence at 555 nm and absorbance at 530 nm of with Al3+. • LOD values for Al3+ were determined ∼1.0 nM. • Both of these probes were used to image the cation in C6 cells. To address limitations like susceptibility to hydrolysis of an imine bond and low selectivity of rhodamine based chemosensors, we report here two rhodamine dyes, namely, L-Et i.e. 3′,6′-bis(ethylamino)-2′,7′-dimethyl-2-(2-morpholinoethyl)spiro[ isoindoline -1,9′- xanthen ]-3-one and L-Pr i.e. 3′,6′-bis(ethylamino)-2′,7′-dimethyl-2-(3-morpholinopropyl)spiro[ isoindoline -1,9′- xanthen ]-3-one for detection of Al3+ in 10 mM HEPES buffer in H 2 O/EtOH = 1:9 (v/v) (pH 7.4). Both the probes detect exclusively Al3+ among 16 different metal ions. The sensing ability has been achieved by noting color change (colorless to pink), increment in absorption intensity at 530 nm and fluorescence intensity at 555 nm. Opening of spirolactam ring of the chemosensors followed by complexation with Al3+ is responsible for such changes. A 1:1 complex is formed by both the probes with high association constant (1.14 × 105 M−1 for L-Et and 1.17 × 105 M−1 for L-Pr). The limit of detection values of L-Et and L-Pr towards Al3+ have been determined as 1.7 nM and 1.1 nM, respectively signifying very high sensitivity. These have been successfully applied in cell imaging studies in C6 cells. Introduction of a methylene group does not influence spectral properties vividly. As both the probes do not contain any imine bond, the possibility of hydrolysis in the presence of Al3+ has been avoided. [ABSTRACT FROM AUTHOR]

[Display omitted] • Plasmon-enhanced fluorescence-Raman scattering (PEF-SERS) sensors are reviewed. • Signal enhancement mechanisms for fluorescence/Raman probes are explained. • Construction strategies for plasmonic enhancement substrates are highlighted. • Several signal readout modes and advanced practical applications are overviewed. • The present challenges and perspectives are proposed. Plasmonic nanomaterials could improve various optical performance including fluorescence emission, Raman scattering, infrared absorption, etc. Among them, plasmon-enhanced fluorescence (PEF) can realize high-sensitivity sensing and super-resolution imaging quickly, but with inferior multiplexed detection capability. Surface-enhanced Raman scattering (SERS) can offer fingerprint-like spectra for multiplexing, but its imaging speed and resolution are limited. The PEF-SERS integrated sensors could congregate their individual strengths while overcoming inherent weaknesses. Specifically, they can use fluorescence signals to rapidly screen out "suspicious" locations within numerous samples or a broad area, and then conduct multi-peak SERS measurements there to gather more detailed information. Besides, cross-verification of PEF and SERS results is possible to realize self-correction. Hence, many existing issues could be addressed including sensitivity, accuracy, speed, and multiplexing. Attracted by these superior advantages, we review here the interaction between plasmonic nanomaterials and fluorescence/Raman probes to explain enhancement mechanisms, the construction strategies for plasmonic substrates with better PEF-SERS performance, different modes for transforming analyte's information into measurable optical signals, as well as the main application in substance research, disease diagnosis, cell imaging, drug delivery. We believe, a deeper understanding of the state-of-arts of multifunctional plasmonic platforms could provide a generic guideline for their future development and practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • A convenient approach to construct excimer emissive luminogens was established. • A double-bond linker between π-moiety and side-moiety is essential for AIE. • The structure-luminescence relationship was elucidated. • The high-resolution image of living Hela cells was observed. The excimer emission based on discrete π-stacked dimers of polycyclic π-systems has generated significant interest in the structure-luminescence relationship of excimers owing to their ultra-large Stokes shift. Herein, a series of excimer emissive luminogens were obtained by conjugating different polycyclic aromatic aldehydes (anthraldehyde, pyrenealdehyde and perylenealdehyde) with triphenylmethylamine. In crystalline states, all the molecules were arranged in the form of π-stacked arene dimers which were spatially isolated from each other by the bulky triphenylmethyl groups, and thus emitted bright excimer emission. The anthracene and pyrene derivatives showed fluorescence enhancement responses to grinding and the enhanced fluorescence could recover to the original state upon heating. The aggregation-induced emission (AIE) properties of them were dependent on the shapes and sizes of the polycyclic aromatic groups. The pyrene derivative showed the most excellent excimer-based AIE behavior among them. All of them were more apt to exhibit the excimer emission when formed nanoparticles with pluronic F-127 than that without pluronic F-127. Furthermore, PETP was utilized for bioimaging of living Hela cells and the high-resolution image was observed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A framework nucleic acids (FNAs) fluorescent nanoprobe was constructed. • The detection of multiple DNA repair enzymes in living cells was realized. • This method exhibits good selectivity and high sensitivity. • The FNAs enter the cell autonomously and image UDG and APE1. DNA repair enzymes play pivotal roles in DNA damage repair. Imaging multiple DNA repair enzymes in living cells is significant for DNA damage repair-related biological study and disease diagnosis. Here, we constructed a framework nucleic acids (FNAs) fluorescent nanoprobe for imaging multiple DNA repair enzymes in living cells. Uracil DNA glycosylase (UDG) and human apurinic/apyrimidinic endonuclease 1 (APE1) were used as the target analytes. Two double-stranded DNA probes (dsDNA1 and dsDNA2) were designed. dsDNA1 contained four uracil (U) bases for UDG recognition and was labeled with black hole quencher2 (BHQ2) /cyanine5 (Cy5). dsDNA2 contained one apurinic/apyrimidinic (AP) site for APE1 recognition and was labeled with black hole quencher1 (BHQ1) /fluorophore carboxyfluorescein (FAM). To obtain the FNAs fluorescent nanoprobe, dsDNA1 and dsDNA2 were attached to two vertices of a DNA tetrahedron (a type of FNAs). Under the action of UDG and APE1, dsDNA1 and dsDNA2 were both dissociated, generating fluorescence of Cy5 and FAM. Among them, Cy5 indicated the activity of UDG and FAM indicated the activity of APE1. This method had good sensitivity to UDG and APE1, and the detection limits were 0.0012 U/mL and 0.057 U/mL, respectively. This method also exhibited high selectivity for UDG and APE1. When the FNAs fluorescent nanoprobe was endocytosed, it had little toxicity to normal and cancer cells. Furthermore, this method successfully achieved multiple imaging UDG and APE1 in cancer cells. This study provides a novel strategy for imaging multiple DNA repair enzymes and holds great potential in biological applications and clinical diagnosis. [ABSTRACT FROM AUTHOR]

The detection of pH and glutathione (GSH) is positively significant for the cell microenvironment imaging. Here, to assess the pH value and the concentration of GSH efficiently and visually, a cellulose-based multi-bands ratiometric fluorescence probe was designed by assembling MnO 2 -modified cellulose gold nanoclusters, fluorescein isothiocyanate-grafted cellulose nanocrystals (CNCs) and protoporphyrin IX-modified CNCs. The probe exhibits GSH-responsive, pH-sensitive and GSH/pH-independent fluorescent properties at 440 nm, 520 nm, and 633 nm, respectively. Furthermore, the probe identifies GSH within 4 s by degrading MnO 2 into Mn2+ in response to GSH. Ingeniously, the green fluorescence of the probe at 520 nm was decreased with pH, and the red fluorescence at 633 nm remained stable. Therefore, the probe displayed distinguishing fluorescence colors from pink to blue and from green to blue for the synchronous detection of pH and GSH concentration within 4 s. The design strategy provides insights to construct multi-bands fluorescence probes for the rapid detection of multiple target analytes. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Multifunctional CDs were prepared hydrothermally from eco-friendly Coccinia Grandis. • EC-Dots exhibited uniform globular shape with an average size of 4 nm (QY of 17 %). • EC-Dots emit bright fluorescence that is dependent on the excitation wavelength. • The current research provided a new platform in the field of bioimaging. • Also, the EC-Dots are a versatile component in various types of fluorescent ink. This study adopted an eco-friendly approach for the one-step hydrothermal conversion of sustainable Coccinia grandis into well-dispersed, uniform-sized carbon dots. The resulting eco-friendly carbon dots (EC-Dots) were harnessed for bioimaging and fluorescent ink applications. EC-Dots exhibited an average size of 4 nm. Further, cytotoxicity assessments on live nematodes revealed cell viability > 95 %. In-vivo studies showed excellent uptake and their ability to emit light in multiple colors, including blue, green, and red, achieved by adjusting the excitation wavelength. Additionally, the EC-Dots exhibited robust fluorescence in aqueous solutions and exceptional resistance to photobleaching, rendering them highly effective for generating fluorescent ink for drawing and writing. Thus, this research showcases an environmentally sustainable, cost-effective, and straightforward hydrothermal method for creating biocompatible EC-Dots with diverse hydrophilic properties. These synthesized EC-Dots stand as a promising platform for applications in fluorescent ink and in vivo bioimaging, offering a high level of safety with minimal cytotoxicity. [ABSTRACT FROM AUTHOR]

Five novel dual-state emissive imidazo[1,2- α ]pyridine-based luminogens IP1-5 were rationally designed and prepared by varying the conjugation length and the nature of donor-acceptor (D-A) units. These D-A chromophores displayed cyan, green, yellow, and red fluorescence in the solid state, with full-color emission achieved for the first time through modification of imidazo[1,2- α ]pyridine core. Interestingly, IP1 and IP5 in the solid state exhibited an abnormal remarkable blue-shift emission compared with those in THF, probably due to the highly twisted molecular conformations and solvent effect by theoretical calculations as well as crystal structure analyses. Importantly, IP1-5 revealed remarkable reversible acid-induced acidichromism, accompanied with dual change of colorimetric and fluorometric determination. Viscosity-dependent fluorescence was next conducted, indicting IP1-3 can be utilized for local viscosity detection. Moreover, IP1-5 served as promising candidates for multicolor bioimaging with low cell toxicity and good biocompatibility. Five asymmetric donor-acceptor dual-state emissive imidazo[1,2- ɑ ]pyridines have been synthesized with full color emission acidichromism, viscosity-dependent fluorescence, and biological imaging. [Display omitted] • Five DSE fluorophores IP1-5 based on carbonyl-substituted imidazo[1,2- α ]pyridine have been synthesized and characterized. • IP1-5 exhibited full color solid emission through manipulation of D-A electronic structures and conjugation length. • IP1-5 displayed reversible acidochromism and bioimaging applications with excellent biocompatibility and cell permeability. • IP1-3 showed viscosity-dependent fluorescence with application as potential viscosity sensors. [ABSTRACT FROM AUTHOR]

Determining the activity of lysosomal β-hexosaminidase in cells is of great importance for understanding the roles that these enzymes play in pathophysiological events. Herein, we designed the new fluorescent probe, βGalNAc-Rhod-CM(NEt 2), which consisted of a βGalNAc-linked rhodol unit serving as a β-hexosaminidase reactive fluorogenic moiety and a N,N′ -diethylaminocoumarin (CM(NEt 2)) group acting as a fluorescence marker for determining the degree of cell permeabilization. Treatment of βGalNAc-Rhod-CM(NEt 2) with β-hexosaminidase promoted generation of Rhod-CM(NEt 2), thereby leading to an increase in the intensity of fluorescence of Rhod. However, this probe did not respond to the functionally related glycosidase, O-GlcNAcase. The detection limit of βGalNAc-Rhod-CM(NEt 2) for β-hexosaminidase was determined to be 0.52 nM, indicating that it has high sensitivity for this enzyme. Furthermore, the probe functioned as an excellent fluorogenic substrate for β-hexosaminidase with k cat and K m values of 17 sec−1 and 22 μM, respectively. The results of cell studies using βGalNAc-Rhod-CM(NEt 2) showed that levels of β-hexosaminidase activity in cells can be determined by measuring the intensity of fluorescence arising from Rhod and that the intensity of fluorescence of CM(NEt 2) can be employed to determine the degree of cell permeabilization of the probe. Utilizing the new probe, we assessed β-hexosaminidase activities in several types of cells and evaluated the effect of glucose concentrations in culture media on the activity of this enzyme. [Display omitted] • Development of the sensitive and selective fluorescent probe for β-hexosaminidase. • Determination of levels of β-hexosaminidase activities in several types of cells. • Evaluation of effect of glucose concentrations in media on β-hexosaminidase activity. [ABSTRACT FROM AUTHOR]

In order to further visualize intracellular dynamics, precise imaging of endogenous proteins in live cells was performed using an antigen-binding fragment (Fab)-based Quenchbody (Q-body). The transfected Q-body probe showed an antigen-dependent fluorescence response, enabling the clear visualization and sorting of cells expressing p53, a tumor suppressor biomarker. [ABSTRACT FROM AUTHOR]

Cancer represents a leading cause of death worldwide. Hence, a better understanding of the molecular mechanisms causing and propelling the disease is of utmost importance. Several cancer entities are associated with altered K+ channel expression which is frequently decisive for malignancy and disease outcome. The impact of such oncogenic K+ channels on cell patho-/physiology and homeostasis and their roles in different subcellular compartments is, however, far from being understood. A refined method to simultaneously investigate metabolic and ionic signaling events on the level of individual cells and their organelles represent genetically encoded fluorescent biosensors, that allow a high-resolution investigation of compartmentalized metabolite or ion dynamics in a non-invasive manner. This feature of these probes makes them versatile tools to visualize and understand subcellular consequences of aberrant K+ channel expression and activity in K+ channel related cancer research. [Display omitted] • K+ ions and K+ channels modulate cancer malignancy. • K+ channels are located throughout (intra-) cellular membranes. • Fluorescent biosensors allow high resolution imaging of subcellular signaling events. • Biosensors are valuable tools to investigate metabolic consequences of oncogenic K+ channels. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel rhodamine-based chemosensor RB-Gly-4-NAP (RGN) was prepared for multi-ion detection. • The sensor enables highly selective detection of Hg2+ and trivalent cations (Fe3+, Al3+, Cr3+) across different channels. • Theoretical calculations confirmed the efficacy of the sensor in coordinating with Fe3+, Al3+, Cr3+, and Hg2+. • The sensor shows excellent sensitivity to Fe3+, Al3+, Cr3+, and Hg2+, with LODs of 10.20, 14.66, 58.78, and 73.33 nM. • The sensor has been successfully applied to actual water samples and bioimaging (cell imaging and zebrafish imaging). A novel rhodamine-based multi-ion fluorescent sensor, RGN, was designed and synthesized for the highly selective detection of mercury ions (Hg2+) in ethanol and water systems, as well as trivalent cations (Fe3+, Al3+, and Cr3+) in acetonitrile and water systems using a two-step Schiff base reaction method. Nuclear magnetic titration experiments and theoretical calculations demonstrated that the sensor achieved the detection of the aforementioned metal ions through the fluorescence turn-on phenomenon induced by lactam ring-opening. Density functional theory (DFT) calculation results showed decreased HOMO-LUMO energy gaps and increased dipole moments, indicating the effective coordination of the sensor with the corresponding metal ions to form more stable complexes, thereby achieving detection objectives. Furthermore, the fluorescence turn-on sensor RGN exhibited relatively low detection limits, with limits of detection (LOD) for Fe3+, Al3+, Cr3+, and Hg2+ being 10.20 nM, 14.66 nM, 58.78 nM, and 73.33 nM, respectively. Finally, practical applications of sensor RGN in environmental water samples, L929 cells, and zebrafish were demonstrated, indicating its potential for detecting and tracking Fe3+, Al3+, Cr3+, and Hg2+ in environmental samples and biological systems, with prospects for biomedical applications in the diagnosis and treatment of heavy metal ion-induced diseases. [ABSTRACT FROM AUTHOR]

The sensor MH-4 has a high sensitivity and selectivity to Cu2+ over a wide range of other metal ions in acetonitrile (ACN)/water (v/v 1:1). The fluorescence imaging studies demonstrated the permeability of MH-4 in L929 living cells and the sensing of Cu2+ in the cells. [Display omitted] • A diformyl phenol based optical sensor (MH-4) was developed for the detection of Cu2+. • MH-4 showed high selectivity and sensitivity Cu2+ over other metal ions/anions tested. • MH-4 can detect Cu2+ at nanomolar level. • Mh-4 is suitable for imaging Cu2+ in living cells. Given the critical role of trace copper ion in human health, its sensitive detection in environmental and biological samples is crucial. We, herein, designed and synthesized a diformyl phenol-based turn-off fluorescent sensor ((5-(tert -butyl)-2-hydroxy-1,3-phenylene)bis (methanylylidene)) bis (azanylylidene)) bis(4-hydroxy-2H-chromen-2-one) (MH-4)) for the spectrofluorometric detection of Cu2+ ion, which has sensitive and selective fluorescence quenching over other competitive metal ions. The efficiency and fast response of the sensor were confirmed by UV–Visible, fluorescence spectral changes, which may be due to the formation of coordination bond between MH-4 and Cu2+ ions. The binding stoichiometry of MH-4 with Cu2+ was examined with the help of UV–Vis and fluorescence titrations, and Job's plot, which gives a 1:1 coordination stoichiometry; this is further confirmed through MS studies. The binding constant of the complex was found to be 9.4 x 107 M−1. Then, the absorbance and fluorescence-based detection limits were calculated to define the sensitivity range of the proposed sensor and were found to be 69.30 nM and 37.40 nM, respectively. Finally, a live cell image study of MH-4 in L929 (murine aneuploid fibrosarcoma) cells was also performed to test the cell permeability of MH-4 and its effectiveness for selective detection of Cu2+ in living cells. [ABSTRACT FROM AUTHOR]

β-Galactosidase (β-gal), an enzyme related to cell wall degradation, plays an important role in regulating cell wall metabolism and reconstruction. However, activatable fluorescence probes for the detection and imaging of β-gal fluctuations in plants have been less exploited. Herein, we report an activatable fluorescent probe based on intramolecular charge transfer (ICT), benzothiazole coumarin-bearing β-galactoside (BC-βgal), to achieve distinct in situ imaging of β-gal in plant cells. It exhibits high sensitivity and selectivity to β-gal with a fast response (8 min). BC-βgal can be used to efficiently detect the alternations of intracellular β-gal levels in cabbage root cells with considerable imaging integrity and imaging contrast. Significantly, BC-βgal can assess β-gal activity in cabbage roots under heavy metal stress (Cd2+, Cu2+, and Pb2+), revealing that β-gal activity is negatively correlated with the severity of heavy metal stress. Our work thus facilitates the study of β-gal biological mechanisms. [Display omitted] • An activatable fluorescence probe (BC-βgal) for detecting β-galactosidase was designed. • BC-βgal was high sensitivity and selectivity towards β-gal with fast response (8 min). • BC-βgal imaged the β-gal fluctuation in situ in cabbage roots. • BC-βgal evaluated the β-gal activity under heavy metal stress for the first time. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three novel fluorescence chemosensors were developed for Hg2+ determination based on dethioacetalization reaction. • Sensors displayed highly sensitive and selective to Hg2+ in aqueous system with low detection limit. • Sensor was successfully applied to detect Hg2+ in real water samples and herb extract samples. • Sensor is capable of monitoring Hg2+ in living cell. Mercury ion is one of the most harmful metal ions with significant hazards to the environment and human health. Thus, the development of innovative, sensitive, and selective sensors to help address the detrimental impacts of heavy metal contamination is necessary. In this work, we present three new chemosensors based on the deprotection reaction of the thioacetal group for distinguishing Hg2+ in environmental samples. These chemosensors show good photophysical properties with high quantum yield in aqueous medium. These prepared chemosensors were employed as fluorometric sensors for the determination of Hg2+ through the quenching of fluorescence emission due to the Hg2+-induced hydrolysis of the thioacetal to the aldehyde group. In the presence of Hg2+, chemosensors showed an emissive color transformation from blue fluorescence to non-fluorescence under UV light, which was readily seen by the visual eye. These chemosensors also exhibited highly distinctive selectivity toward Hg2+ over other interfering metal ions, with detection limits of 1.1 ppb, 13.4 ppb, and 12.7 ppb. Moreover, the practical applicability of chemosensor was successfully demonstrated in real water samples and herb extract samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • We present a simplified fluorescent microscopy-surface plasmon resonance (FM-SPR) system. • Real-time simultaneous observation and acquisition of fluorescent carbon dots labeled silk fibroin kinetic processes using FM-SPR system. • The fluorescence image changes fitted well with the SPR signal changes. • The linear detection range was 2.5 μg/mL–100 μg/mL, and the real lowest detection limit reached 0.5 μg/mL. • The association rate and dissociation rate of N-CDs to SF which were 2.65 × 10−5/s and 1.52 × 10 −5/s, respectively. The use of fluorescent carbon dots (CDs) as highly precise biolabeling probes has been widespread in the fields of live cell imaging and protein labeling due to their small size and excellent photoluminescence ability to accurately target specific molecules with surface chemical properties. However, there was a lack of research on the interaction between CDs and labeled molecules. In this work, we presented a novel investigation strategy, the fluorescence microscopy-surface plasmon resonance (FM-SPR) system, which combined the use of fluorescence microscopy and wavelength modulation surface plasmon resonance to study the interaction between CDs and labeled molecules in real-time. Using this system, simultaneously recorded the SPR signals and the fluorescence images on the surface of the FM-SPR sensor chip. We observed the dynamic curve and fluorescence images of the interaction between green emissive nitrogen-doped carbon dots (N-CDs) and silk fibroin (SF) in real-time. The kinetic parameters, the quantitative analysis, and the investigation of the binding could be achieved. The results showed a strong linear relationship between the change in SPR signals and the concentration of N-CDs, with a linear coefficient of 0.99913. The linear detection range was 2.5 μg/mL–100 μg/mL, and the real lowest detection limit reached 0.5 μg/mL. Additionally, the green fluorescence points in the imaging region on the FM-SPR sensor chip increased with the concentration of N-CDs, which was consistent with the change in SPR signals. Using this system we also acquired the association rate and dissociation rate of N-CDs to SF which were 2.65 × 10−5/s and 1.52 × 10−5/s, respectively. This demonstrated the effectiveness of our method in quantitatively analyzing SF labeled with N-CDs. [ABSTRACT FROM AUTHOR]

[Display omitted] • LD-VP emits fluorescence at 520 nm in dioxane and 600 nm in viscous media without any interference from biological entities. • The LD-VP probe is pH-independent. • The quantum yield of probe LD-VP has changed from 0.5 % to 30% as the viscosity rises from 0.9 cP to 953 cP. • Probe LD-VP has provided green images in nonpolar intracellular milieu detection and red images for high viscosity. • Probe LD-VP concurrently labeled mitochondria, lysosomes, and lipid droplets in red and green channels based on intracellular viscosity and polarity. The viscosity and polarity of cells are inherent physical parameters, and changes to these attributes are frequently linked to malfunctioning conditions or different diseases. Cancer cells often harbor elevated nonpolar lipid droplets (LDs), acting as energy reserves. The rise in lipid droplets (LDs) and viscosity, distinctive traits of cancer cells, has motivated us to develop a fluorescent probe based on naphthalimide. The fluorescent marker LD-VP exhibits fluorescence signals at 520 nm in nonpolar dioxane and 600 nm in highly viscous glycerol. This implies that probe LD-VP can furnish details regarding cellular microviscosity and lipid droplets within live cells by providing dual-channel images. The probe LD-VP is chemically inert and harmless, enabling its safe utilization in live cell imaging. We conducted fluorescence imaging based on viscosity using probe LD-VP in the red channel, which is found to be co-localized in both mitochondria and lysosomes. Moreover, the probe effectively marks lipid droplets in the green channel. The probe LD-VP represents a distinctive fluorescent tool capable of monitoring both viscosity and lipid droplet expression in live cells. This tool holds the potential for visualizing physiological abnormalities or pathological conditions. [ABSTRACT FROM AUTHOR]

γ-Glutamyltranspeptidase (GGT) is a cell surface-associated enzyme, which has been proven to be closely related to many diseases. Thus, development of simple and effective GGT-activatable fluorescent probes for early diagnosis of diseases is of great significance. Herein, a series of simple isomeric pyridine-based GGT-activatable fluorescent probes has been successfully designed and synthesized. The preliminary experimental results indicate that Py-GGT-1 has a significant fluorescence response to GGT via a rare fluorescence-off approach. Further fluorescence response experiments, such as the time-/dose-dependent fluorescence change and the selectivity/specificity estimation, reveal that Py-GGT-1 has an excellent ability to monitor endogenous GGT activity. Mechanism studies through HRMS analysis, DFT calculations and molecular docking have theoretically verified the catalytic process between Py-GGT-1 and GGT. To develop its practical application, live-cell imaging and serum-sample analysis were carried out, demonstrating that Py-GGT-1 coud effectively track GGT within cells and organisms. Based its high selectivity and reasonable sensitivity, we expect that the probe will be applied in clinical diagnosis of GGT-related diseases in the future. • We have designed and synthesized a series of simple isomeric pyridine-based probes for GGT detection, which performed a good photophysical property and showed a rapid response to GGT. • Py-GGT-1 was selected as the optimal GGT-activatable probe based on further fluorescence response experiments, such as the time-/dose-dependent fluorescence change and the selectivity/specificity estimation, which revealed that Py-GGT-1 had an excellent ability to monitor endogenous GGT activity. • Mechanism studies through HRMS analysis, DFT calculations and molecular docking theoretically verified its catalytic process between Py-GGT-1 and GGT. • Compared with the reported GGT-activatable probes, our probe shows its simplicity, reliability and rapid response for in vitro monitoring GGT activity with high selectivity and reasonable sensitivity, which is expected to be applied in clinical diagnosis of GGT-related diseases in the future. [ABSTRACT FROM AUTHOR]

Nitroreductase (NTR) is a frequently used biomarker for the assessment of hypoxia level in tumors. As one of the main sources of enzymes, the dysfunction of lysosomes typically leads to various diseases. In this study, an NTR-triggered lysosome-targeting probe, M-TPE-P, was designed based on a tetraphenylethylene core. DFT calculation indicated that the probe possessed a narrow singlet–triplet energy gap (ΔE ST), rendering it an efficient photosensitizer. The docking affinity of M-TPE-P to NTR revealed a strong structural match between them. Photophysical properties demonstrated that the probe exhibited high selectivity and sensitivity in a broad pH rang for detecting NTR with k cat / K m as 2.18 × 104 M−1 s−1. The detection limit was determined to be 53.6 ng/mL in 80 % PBS/DMSO solution. Cell imaging studies showed the probe could trace intracellular NTR behavior with green fluorescence. The colocalization analysis indicated its excellent lysosome-targeting specificity. In addition, the probe exhibited effective ROS generation ability and significant PDT effect after NIR irradiation, positioning it as a promising photosensitizer for cancer treatment. Schematic Representation of the NTR-responsive fluorescence turn-on photosensitizer for lysosomes imaging and photodynamic therapy. [Display omitted] • An NTR-responsive fluorescence turn-on probe M-TPE-P for lysosomes imaging was developed. • M-TPE-P showed high selectivity and sensitivity with a low detection limit toward NTR. • M-TPE-P displayed time-dependent behaviors, excellent lysosomes targeting and ROS generation ability in 4T1 cells. • The structure relationship between the probe M-TPE-P and NTR was demonstrated by DFT and docking calculations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two spirobifluene-based turn-on fluorescent probes for Cysteine were synthesized. • The probes shows highly selectivity for Cysteine. • The probes had been applied to imaging Cysteine under two-photon excitation. • One probe displayed excellent detection limit for Cysteine. Two spirobifluene-based fluorescent probes SPF1 and SPF2 , were designed and synthesized. The probes displayed "turn-on" fluorescence response for Cysteine. One of the challenges in developing a Cysteine probe is to secure high selectivity. SPF1/SPF2 can discriminate Cysteine from GSH as well as Hcy, and showed high substrate selectivity. The detection limit of SPF1 is 36 nM, which is excellent comparing with other optical sensors for Cysteine. The sensing mechanism of SPF1/SPF2 was verified by experimental data and theoretical calculations. There was a good linear relationship between the fluorescence intensity of SPF1/SPF2 and the concentration of Cysteine. The MTT tests indicated that SPF1/SPF2 had low cytotoxicity and good biocompatibility. Theoretical calculations demonstrated that SPF1 , SPF2 , and their related reaction products with Cysteine exhibited good two-photon absorption properties. Finally, SPF1/SPF2 had been successfully applied to the imaging of Cysteine in living cells under two-photon excitation. [ABSTRACT FROM AUTHOR]

Under physiological conditions, K(TPE)EFYp is converted to K(TPE)EFY containing hydroxyl by dephosphorylation of ALP and fluorescence is turned on. [Display omitted] • An enzyme-responsive biosensor with AIE properties. • A peptide-based Fluorescent supramolecular hydrogel (FSH) material. • Sol-gel phases transformation to determine alkaline phosphatase (ALP) activity. • "Turn-on" strategy due to the AIE effect has a higher sensitivity and a lower LOD. Alkaline phosphatase is an important biomarker for medical diagnosis. An enzymatic fluorescence supramolecular hydrogel with AIE properties was developed and used for sensing alkaline phosphatase in vitro and in living cells. In the presence of ALP, K(TPE)EFYp was partially converted to the hydrogelator K(TPE)EFY and self-assembled into nanofibers to form Hydrogel. With the sol–gel transition and the AIE effect, the fluorescence emission was turned on. The linear concentration range of ALP activity in vitro quantified by this method was determined as 0–3 U/L with a LOD at 0.02 U/L. In addition, cell imaging and serum experiment showed that K(TPE)EFYp could also be used to detect ALP activity in living cells and biological samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • The first coumarin-based HNO donor (CD1) was developed. • HNO-releasing has a t 1/2 ∼90 min under physiological conditions. • The fluorescence intensity increased by about 4.9-fold. • HNO release can be visualized by cellar images. Nitroxyl (HNO), the single-electron reduction product of nitric oxide (NO), has attracted great interest in the treatment of congestive heart failure in clinical trials. In this paper, we describe the first coumarin-based compound N -hydroxy-2-oxo-2H-chromene-6-sulfonamide (CD1) as a dualfunctional HNO donor, which can release both an HNO signaling molecule and a fluorescent reporter. Under physiological conditions (pH 7.4 and 37 °C), the CD1 HNO donor can readily decompose with a half-life of ∼90 min. The corresponding stoichiometry HNO from the CD1 donor was confirmed using both Vitamin B 12 and phosphine compound traps. In addition to HNO releasing, specifically, the degradation product 2-oxo-2H-chromene-6-sulfinate (CS1) was generated as a fluorescent marker during the decomposition. Therefore, the HNO amount released in situ can be accurately monitored through fluorescence generation. As compared to the CD1 donor, the fluorescence intensity increased by about 4.9-fold. The concentration limit of detection of HNO releasing was determined to be ∼0.13 μM according to the fluorescence generation of CS1 at physiological conditions. Moreover, the bioimaging of the CD1 donor was demonstrated in the cell culture of HeLa cells, where the intracellular fluorescence signals were observed, inferring the site of HNO release. Finally, we anticipate that this novel coumarin-based CD1 donor opens a new platform for exploring the biology of HNO. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple single step multicomponent ugi type reaction was carried out to yield N-(tert-butyl)-2-(furan-2-yl)imidazo[1,2- a ]pyridine-3-amine (TBFIPA). • The synthesized TBFIPA was characterized using 1H NMR, 13C NMR and HRMS spectroscopic methods. • The selective & sensitive detection was identified using hypsochromic shift (lab : 335nm → 285nm) & fluorescence quenching. • The proposed mechanism is evident from Job plot, 1H NMR titration, ESI-MS data and theoretical DFT calculation. • The Cr3+ ion-selective TBFIPA was successfully applied in the design of a user-friendly silica-based portable test kits. • Also, the fluorescence quenching ability of TBFIPA in presence of Cr3+ ions are validated by imaging onion epidermal cells. • Real samples contaminated with Cr3+ ions were identified using TBFIPA with an appropriated relative error percentage. A simple single step one pot multicomponent reaction was performed to synthesize N-(tert -butyl)-2-(furan-2-yl)imidazo[1,2- a ]pyridine-3-amine (TBFIPA). The synthesized TBFIPA was subjected to library of cations to study its ability for selective and sensitive detection of specific metal ions. Selective detection of chromium ions by TBFIPA were found from the significant hypsochromic shift (335 nm → 285 nm) in the UV–Visible spectra. The fluorescent TBFIPA displays complete quenching of fluorescence under UV lamp (365 nm) only in the presence of chromium without the interference of common metal ions. Binding constant (k a) obtained from Benesi-Hildebrand plot is 0.21 × 105 M−1, limit of detection (LOD) and limit of quantification (LOQ) of TBFIPA toward Cr3+ ions are 4.70 × 10−7 M and 1.56 × 10−7 M, respectively. The mechanism proposed during complex formation were supported by stoichiometric Job continuous variation plot, 1H NMR titration and ESI-MS spectroscopic data. All the experimental confirmation for complex formation were corroborated with theoretical DFT studies optimized using RB3LYP/6-31G(d) basis set. The selectivity and sensitivity of TBFIPA toward Cr3+ ions are found suitable to design a user-friendly silica based portable test kit. Alongside, TBFIPA was successfully utilized for imaging onion epidermal cells. Furthermore, the results obtained for biological, environmental, and industrial samples provided solid evidence to estimate chromium ions using TBFIPA in these real samples. [ABSTRACT FROM AUTHOR]

We have installed cycloalkylamino auxochromes on naphthalimide (5a - 5e) and nitrobenzoxadiazole (6a - 6e) dyes. Their photophysical characterization revealed that the cyclobutylamino auxochrome in both dyes (5b and 6b) demonstrated high quantum yield and fluorescence brightness compared to their azetidine counterparts (5 and 6) in aqueous solution. The computational studies were performed to substantiate the experimental photophysical results. Cytotoxicity assay in breast adenocarcinoma (MDA-MB-231) and non-cancerous human embryonic kidney 293 (HEK-293) cells indicated significant biocompatibility of cyclobutylamino auxochrome. Moreover, cellular imaging and photostability experiments demonstrated the practical application of cycloalkylamino auxochromes. [Display omitted] • Cycloalkylamine substituted naphthalimides (5a-5e) and 4-nitrobenzoxadiazole (6a-6e) were synthesized and compared with azetidine substituted counterparts (5 and 6) for their fluorescent properties. • Cyclobutylaminated derivatives of naphthalimides and 4-nitrobenzoxadiazole (5b and 6b) show enhanced quantum yields and fluorescence brightness in comparison to their azetidine counterparts (5 and 6). • Compounds 5b and 6b show better biocompatibility and excellent cell penetration in MDA-MB-231 breast cancer cells than their reference standards (5 and 6). [ABSTRACT FROM AUTHOR]

The development of bifunctional AIEgens for direct delivering and visualizing bioactive species together remains a great challenge to date. Herein, we fabricated a novel photoactivatable nitric oxide (NO) donor with a built-in AIE fluorophore, which can rapidly release NO and AIEgen upon light irradiation. The ultrafast NO generation can be obtained in 2.1 ps, with the yielding of a greatly drastic fluorescence turn-on AIEgen probe (300,000-fold intensity enhanced). Using this NO donor, real-time cell images of NO-releasing through the emission of AIEgen were successfully achieved through direct excitation of the donor in cells in situ. [Display omitted] • The first AIE-caged photoactive NO donor was developed. • Ultra-fast NO release (2.1 ps) was achieved by photoexcitation. • An extremely high fluorescence intensity was obtained (300,000-fold). • The NO release was visualized by fluorescent technology. • Cell imaging was successfully performed using this NO donor. [ABSTRACT FROM AUTHOR]

Designing functionalized MOFs with specific reactivity and NIR photoelectrochemical and fluorescent response is critical for developing biosensing systems. Herein, SCy7, a conjugate macrocycle ligand with a specific fluorescence responsive group to HClO, was designed and synthesized. Responsive Nd-MOF nanorods were successfully prepared by using SCy7 as the organic ligand and Nd3+ as the metal central ion. Nd-MOF nanorods show good absorption characteristics in the wavelength range of 200–1200 nm with a band gap of 0.89 eV. Nd-MOF nanorods were employed as a photoactive material to construct a near-infrared photoelectrochemical cytosensor for MCF-7 cells by integrated with an aptamer. The photocurrent variation exhibits a good linear response to MCF-7 cells in the concentration range of 50–1.0 × 107 cells mL−1, and a comparatively low detection limit of 18 cells mL−1 (S/N = 3). The NIR PEC cytosensor was also employed for monitoring endogenous HClO released from MCF-7 cells as being stimulated by PMA. HClO is an electron acceptor that can convert the anodic photocurrent into cathodic photocurrent, thus achieving monitoring HClO through the conversion of photocurrent polarity. Furthermore, Nd-MOF was coated with F127 to improve its hydrophilicity and biocompatibility, and to provide a Nd-MOF@F127 with a fluorescence emission peak at 830 nm. Nd-MOF@F127 show specific fluorescence response to HClO, and thus was successfully used in imaging HClO variation in cells and breast cancer bearing mice. [Display omitted] • Nd-MOF nanorods with specific response to HClO were successfully synthesized. • A NIR PEC cytosensor based on Nd-MOF was developed for MCF-7 cells assaying. • Real-time monitoring HClO was achieved by photocurrent polarity conversion. • Fluorescence imaging HClO in cells and mice was performed by using Nd-MOF@F127. [ABSTRACT FROM AUTHOR]

In this work, arginine functionalized niobium carbide MXene quantum dots (arginine-Nb 2 C MQDs) were synthesized using Nb 2 AlC, NaOH and arginine as reagents. The as-synthesized probe showed bluish-green fluorescence under UV light at 365 nm. The structural and morphological changes of as-synthesized arginine-Nb 2 C MQDs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy and high-resolution transmittance electron microscopy (HR-TEM). The synthesized fluorescent arginine-Nb 2 C MQDs were stable, with an average size of 1.92 ± 0.52 nm. As-synthesized arginine-Nb 2 C MQDs act as a sensor for detecting superoxide anion (O 2 •−) via a fluorescence "turn-off" mechanism with the detection limit of 31.89 nM. The fluorescence of arginine-Nb 2 C MQDs is quenched by O 2 •− via dynamic fluorescence quenching mechanism. Fascinatingly, the synthesized arginine-Nb 2 C MQDs showed negligible cytotoxicity on HeLa cells and acted as promising candidates for sensing of O 2 •− in Saccharomyces cerevisiae cells. [Display omitted] • HF-free synthetic strategy was used for the fabrication of arginine-Nb 2 C MQDs. • Arginine-Nb 2 C MQDs act as a fluorescent sensor for selective detection of O 2 •−. • The developed approach exhibited an impressive detection limit of 31.89 nM for O 2 •−. • Arginine-Nb 2 C MQDs served as probe for cell imaging with minimal cytotoxicity. • The developed technique was used to determine O 2 •− in environmental samples. [ABSTRACT FROM AUTHOR]

A novel NIR probe based on oxazolonaphthoimidazo[1,2- a ]pyridine-malononitrile (ONIM) conjugate linked by vinyl linkage was designed and synthesized for the detection of cyanide ion. [Display omitted] • An orange emitting sensor ONIM (712 nm) with D-π-A framework is synthesized. • The ONIM emission is retained in the solid state. • ONIM could sense cyanide ion without interference of other anions. • Sensing mechanism of cyanide sensing was confirmed by 1H NMR and DFT calculations. • Live cell imaging in human breast cancer cell MDA-MB 231 and as solid state sensor was achieved. Cyanide is undoubtedly dangerous and fast acting chemical employed in various industrial applications with toxic side effects, which raises urgent need for its monitoring. In this context, oxazolonaphthoimidazo[1,2- a ]pyridine-malononitrile (ONIM) conjugate linked by vinyl linkage was designed, synthesized and characterised by FT-IR, NMR and mass spectrometry. The developed probe has been evaluated for the colorimetric and fluorometric detection of cyanide ion. An obvious color change with unique rapid " turn-off " fluorometric response was observed within 5 s upon addition of CN– thus reflecting its better acuteness and sensitivity over other competing anions. The developed probe exhibits a detection limit of 9.54 nM which is very low in comparison to maximum permitable amount of cyanide in drinking water (1.9 µM). The probe is stable within the p H range of 2–9 and suitable for the recognition of CN– in the p H range of 7 to 10, specially at neutral p H conditions. The chemodosimetric approach based detection mechanism was authenticated by 1H NMR titration and DFT calculations. The solid state applications were established by utilising ONIM impregnated TLC plates and filter paper in cyanide recognition. The solid state emissive behaviour of ONIM offers on-spot detection of the cyanide anion. Additionally, the practicability of ONIM has been extended in live cell imaging of CN– in human breast cancer cell (MDA-MB-231), which revealed a " turn-off " fluorescence response for the probe in the presence of CN– ion. [ABSTRACT FROM AUTHOR]

[Display omitted] • NIR sensor for high-sensitive and selective detection and removal Cu2+ in living cells and environment. • Phthalocyanine based dual fluorescence and colorimetric sensor. • NIR fluorescence and colorimetric changes through cis- / trans interconversion. • Binding mechanism towards Cu2+were systematically revealed. Cu2+ sensing and removal are of great significance for environment protection and human health. Herein, multifunctional Cu2+ sensor system for both detection and removal of intracellular and environmental Cu2+ based on trans/cis interconversion of silicon phthalocyanine (SiPc) was developed. This phthalocyanine based Cu2+ sensor shows remarkably dual-mode NIR fluorescence and colorimetric responses for recognition of Cu2+, resulting in insoluble chelate for Cu2+ removal as well as the extremely high anti-interference in the presence of various anions and cations. The binding mechanism and stoichiometry ratio were systematically revealed. Intracellular fluorescence imaging in MCF-7 cells demonstrated that Cu2+ could be efficiently detected in living cells and form insoluble chelate for clearance. As the result, this novel phthalocyanine based multifunctional sensor can be used for dual-mode NIR fluorescence/colorimetric detection and removal of Cu2+ in either complicated environment or biological systems. [ABSTRACT FROM AUTHOR]

• Black carrots are an excellent source of carbon dot production. • Biomass-derived CDs demonstrate high anti-metastatic potential;. • CDs are useful for image-guided anti-cancer therapy;. • We explain the basis for the excitation-independent emission wavelength of CDs at 612 nm. This paper explains the basis for the excitation energy-independent fluorescence emission of biomass-derived carbon dots (CDs) and shows that these CDs have excellent anti-melanoma and anti-metastatic potential. Additionally, we demonstrate that the black carrots´-derived CDs can be exploited as cell cycle-sensing agents, because of the interaction with chromatin material. Besides their optical properties, fluorescent CDs have gained increased attention for image-guided cancer treatment due to their water solubility, environmental friendliness, affordability, ease of synthesis, and primary biocompatibility. CDs have excellent photostability, determined by their precursors and synthesis pathways. In this study, CDs with chemically homogenous surface functional groups were made using a hydrothermal technique from black carrot extract, an anthocyanin-rich substance derived from biomass. The anti-cancer and anti-metastatic properties of black carrot-derived CDs can be attributed to flavylium cations on the surface, spherical forms, and high water dispersibility. Most importantly, these CDs demonstrate a stable emission at a single wavelength, 612 nm, independent of the excitation energy, which we have explained theoretically for the first time. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Al3+ Schiff base probe JHK was designed and synthesized. • JHK has high selectivity, high fluorescence quantum yield and low detection limit for Al3+. • JHK was successfully applied to living cells and zebrafish. A novel fluorescent probe N'-(2-hydroxybenzylidene)-indole-3-formylhydrazine (JHK) was designed and synthesized based on the condensation reaction of indole-3-formylhydrazine and salicylaldehyde. The probe JHK solution could highly selectively recognize Al3+ by the obvious fluorescence enhancement (288-fold) after adding Al3+. And the probe solution with Al3+ had a very high fluorescence quantum yield (89.29 %). The detection limit was calculated to be 1.135 nM, which was significantly lower than many reported detection limits, indicating that the probe JHK had pretty good sensitivity. The ratio of JHK to Al3+ (1:1) and the sensing mechanism were determined by Job's plot, 1H NMR spectra, FTIR spectra, ESI-MS and Gaussian calculation. The probe solution and medium-speed filter paper were successfully used to make test papers for more convenient detection of Al3+. Furthermore, the probe JHK had been successfully applied to the detection of Al3+ in real water, zebrafish and living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • The probe EDPH specializes in the detection of H 2 S with high selectivity, high sensitivity and good detection limits. • The probe EDPH has been shown to have applications in intracellular fluorescence imaging. • Purine-based fluorescent probes for the detection of H 2 S are a new direction. Hydrogen sulfide (H 2 S) is a gas with a toxic odor that plays an irreplaceable role in physiological activities within the mammalian body. Therefore, it is important to do the distribution and quantitative detection of H 2 S in mammalian cells. In this paper, a fluorescence probe (EDPH) based on purine scaffold was designed and synthesized with high sensitivity and good selectivity. H 2 S induced ether bond breakage in EDPH , resulting in a significant redshift of the absorption band (from 370 nm to 500 nm) with a Stokes shift of 130 nm. After the addition of H 2 S, the fluorescence intensity of EDPH showed a good linear correlation with the concentration of H 2 S, which enabled the quantitative detection of H 2 S with a low limit of detection (41 nM). Finally, the EDPH was applied to the cellular Hele, and the probe has good cellularity imaging capability for the detection of H 2 S in living systems. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) plays important roles in both physiology and therapeutics. Nonetheless, the in-situ monitoring of NO release from most existing donors is challenging, inhibiting advanced research in both chemistry and biology. In this study, we introduce an innovative photochemotherapeutic agent that incorporates a nitroaniline NO moiety with an integrated pyrene fluorophore. This design enables controlled NO release upon light irradiation, allowing for precise quantification through a dramatic fluorescence enhancement (with a 3000-fold increase in intensity). Ultrafast spectroscopy data revealed that the NO release process is exceptionally rapid, completing within 13.3 ps. Additionally, the donor's fluorescence was successfully utilized for in situ cell imaging upon direct photoexcitation. Consequently, using this fluorescent probe enables the accurate visualization of NO release kinetics, dosage, and localization in real-time. The unique advantages of this NO donor are anticipated to significantly advance research in NO chemistry and biology. [Display omitted] • The first pyrene-based photoactivated NO donor was fabricated. • Photoactive ultrafast NO release (13.3 ps) was obtained. • Real-time NO-releasing was monitored by a strong fluorescent probe (3000-fold). • Cellular imaging was performed to demonstrate NO-releasing in situ. [ABSTRACT FROM AUTHOR]

A novel cancer cell and lysosome dual-targeted photosensitizer (PS) termed by BMP was developed for fluorescence imaging and photodynamic therapy (PDT). BMP consists of a porphyrin(Zn) core with appropriate singlet-triplet state distribution enables it to function as an imaging agent as well as a PS, a biotin moiety that can target cancer cells, and a morpholine group specific to lysosomes. Intracellular experiments demonstrated that the dual-targeted photosensitizer BMP could preferably accumulate in cancer cells and subsequently locate within lysosome organelles. Upon irradiation, BMP could generate red fluorescence emission (Φ em = 6.3%) and singlet oxygen (1O 2 , Φ Δ = 55%) for the dual functionality of cell imaging and PDT, respectively. Notably, BMP exhibited much higher photocytotoxicity toward cancer cells (A549 cells) compared to normal cells (BEAS-2B cells). Importantly, 1O 2 produced by BMP induced oxidative damage of lysosomes, and subsequently triggered cell death of A549 cells, as evidenced by the loss of morphological integrity and cell rupture. A cancer cell and lysosome dual-targeted photosensitizer BMP was designed to generate red emission and singlet oxygen (1O 2) simultaneously, which were utilized successfully for dual-targeted fluorescence imaging and photodynamic therapy. [Display omitted] • A dual-targeted photosensitizer was designed and synthesized by modularization. • Biotin acted as a targeting ligand for cancer cells, and morpholine was selected as the lysosome-specific group. • Red fluorescence and singlet oxygen generation were achieved for fluorescence imaging and PDT of cancer cells simultaneously. [ABSTRACT FROM AUTHOR]

The abnormally elevated expression level of glutathione (GSH) has been observed in various human cancer cells and tissue. Thus, effective methods for glutathione detection are of great importance in early diagnosis of cancer. However, many fluorescent probes for GSH detection suffer from the interference of the abundantly existent nucleophilic biomolecules in biological environment. In this work, we propose a sequential activation strategy to overcome this problem by designing and synthesizing a series of 1,3,5-triazinyl resorufin turn-on fluorescent probe (Probes 1–3). As two electrophilic sites are presented in probes, GSH sequentially reacts with the resorufin and the triazine moiety, resulting in significant fluorescence augmentation (up to 165.0-fold). Designed probes possess low limit of detection as low as 1.8 μM). Cellular fluorescent imaging has been successfully applied to selectively detect GSH in several living cells. [Display omitted] • Novel sequential activation strategy allows the Probe 1–3 to detect GSH with high selectivity. • Designed fluorescent probes exhibited strong fluorescence intensity as response. • Designed probes realized GSH visualization in multiple cells with high fidelity. [ABSTRACT FROM AUTHOR]

Telomerase (TE) is a promising diagnostic and prognostic biomarker for many cancers. Quantification of TE activity in living cells is of great significance in biomedical and clinical research. Conventional fluorescence-based sensors for quantification of intracellular TE may suffer from problems of fast photobleaching and auto-fluorescence of some endogenous molecules, and hence are liable to produce false negative or positive results. To address this issue, a fluorescence-SERS dual-signal nano-system for real-time imaging of intracellular TE was designed by functionalizing a bimetallic Au@Ag nanostructure with 4- p -mercaptobenzoic acid (internal standard SERS tag) and a DNA hybrid complex consisted of a telomerase primer strand and its partially complimentary strand modified with Rhodamine 6G. The bimetallic Au@Ag nanostructure serves as an excellent SERS-enhancing and fluorescence-quenching substrate. Intracellular TE will trigger the extension of the primer strand and cause the shedding of Rhodamine 6G-modified complimentary strand from the nano-system through intramolecular DNA strand displacement, resulting in the recovery of the fluorescence of Rhodamine 6G and decrease in its SERS signal. Both the fluorescence of R6G and the ratio between the SERS signals of 4- p -mercaptobenzoic acid and Rhodamine 6G can be used for in situ imaging of intracellular TE. Experimental results showed that the proposed nano-system was featured with low background, excellent cell internalization efficiency, good biocompatibility, high sensitivity, good selectivity, and robustness to false positive results. It can be used to distinguish cancer cells from normal ones, identify different types of cancer cells, as well as perform absolute quantification of intracellular TE, which endows it with great potential in clinical diagnosis, target therapy and prognosis of cancer patients. [Display omitted] • A dual-signal nanosensor was developed for imaging of telomerase in living cells. • Au@Ag nanoparticles served as fluorescence quenching and SERS enhancing substrate. • The results of the fluorescence and SERS channels can provide mutual confirmation. • The SERS channel of the nanosensor can help identify false positive results. [ABSTRACT FROM AUTHOR]

Herein, a mesoporous silica nanoparticle (MSN) based ratiometric fluorescence nanosensor (MSN-BA-SiCD) with improved performance was designed for monitoring hydrogen peroxide (H 2 O 2). Specifically, H 2 O 2 response molecule (BA) with AIE feature was synthesized and encapsulated into MSN channel as the fluoresent recognition site. Afterwards, silane-modified carbon dot (SiCD) was covalently connected to the MSN surface which can effectively prevent the leakage of BA and improve the water dispersibility of the nanosensor. The presence of H 2 O 2 could result in a "turn-on" fluorescence of BA as well as concurrent variation in the fluorescence resonance energy transfer (FRET) signal between SiCD and BA. MSN-BA-SiCD displays a specific blue-to-green resolved emission change in response to H 2 O 2 and the detection limit can be as low as 4.78 × 10−6 M. In addition, the nanosensor exhibited enhanced photostability due to the protection of the material framework. Moreover, the nanosensing system was successfully applied to detect H 2 O 2 in beer, orange juice and living cells. The excellent water dispersibility and photostability of the nanosensor, together with high specificity and biocompatibility, constituted an advanced set of characteristics among existing MSNs, which was expected to further promote the development of H 2 O 2 sensors in the environmental and biological fields. [Display omitted] • A ratio fluorescence nanosensor is designed based on carbon dot modified MSN. • Selective and sensitive detection of H 2 O 2 is achieved by FRET based ratio sensing. • Improved water dispersibility and photostability are exhibited for the nanosensor. • The nanosensor is successfully applied in drink samples and cell imaging. [ABSTRACT FROM AUTHOR]

The Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP1) is a convergent node for oncogenic cell-signaling cascades. Consequently, SHP1 represents a potential target for drug development in cancer treatment. The development of efficient methods for rapidly tracing and modulating the SHP1 activity in complex biological systems is of considerable significance for advancing the integration of diagnosis and treatment of the related disease. Thus, we designed and synthesized a series of imidazo[1,2,4] triazole derivatives containing salicylic acid to explore novel scaffolds with inhibitory activities and good fluorescence properties for SHP1. The photophysical properties and inhibitory activities of these imidazo[1,2,4] triazole derivatives (5a-5y) against SHP1PTP were thoroughly studied from the theoretical simulation and experimental application aspects. The representative compound 5p exhibited remarkable fluorescence response (P: 0.002) with fluorescence quantum yield (QY) of 0.37 and inhibitory rate of 85.21 ± 5.17% against SHP1PTP at the concentration of 100 μM. Furthermore, compound 5p showed obvious aggregation caused quenching (ACQ) effect and had high selectivity for Fe3+ ions, good anti-interference and relatively low detection limit (5.55 μM). Finally, the cellular imaging test of compound 5p also exhibited good biocompatibility and certain potential biological imaging application. This study provides a potential way to develop molecules with fluorescent properties and bioactivities for SHP1. [Display omitted] • Compound 5p was a fluorescent molecule with good quantum yield and inhibitory activity against SHP1. • The inhibitory activity of compound 5p obviously related with fluorescence response. • The activity of SHP1 enzyme could be adjusted effectively by binding capability of compound 5p to Fe3+. [ABSTRACT FROM AUTHOR]

[Display omitted] • A mitochondria-targeting fluorescence probe NIR1 for H 2 S visualization. • NIR1 has excellent detection limits as low as 30.2 nM. • NIR1 was successfully applied for H 2 S imaging analysis in living inflammatory mice. The mechanism of the interaction between the signaling molecule hydrogen sulfide (H 2 S) and mitochondria and its related diseases is difficult to elusive. Thus it is urgent to develop effective methods and tools to visualize H 2 S in mitochondria and in vivo. In this work, a robust mitochondrial-targeting NIR fluorescence "turn-on" fluorescent probe, NIR1, was reported, by adopting a Changsha-OH near-infrared (NIR) dye as the NIR fluorophore, a 2,4-dinitrophenyl (DNB) moiety as both the responsive site of the H 2 S and the fluorescence quenching group of the NIR fluorophore, and an oxygen onium ion site as the mitochondria-targeting group, for the detection and analysis of H 2 S in living Raw 264.7 cells and drug-induced inflammatory mice models. NIR1 exhibited a much smaller background fluorescence signal in lack of H 2 S, whereas strong enhanced NIR fluorescence "turn-on" was detected in the presence of H 2 S, these results showed a low detection limit (30.2 nM) for quantitative detection of H 2 S in aqueous solutions with concentrations ranging from 0 to 1 μM H 2 S. These characteristics were beneficial to direct detection and imaging analysis of H 2 S in complicated biosystems. Therefore, first, NIR1 was applied for the NIR detection of mitochondrial H 2 S in living inflammatory cells with satisfactory results. Finally, NIR1 was applied to detect H 2 S in drug-induced inflammatory mice models with agreeable results, demonstrating that NIR1 as a molecular tool has an excellent practical application in the study of the interaction between inflammatory and H 2 S. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is a multifunctional gaseous signaling molecule that plays a vital role in several biological processes. In the present study, a BODIPY-based fluorescent probe called 8-[4-((1,4,7,10-tetraazacyclododecane)methyl)phenyl]-4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a, 4a-diaza- s -indacene (BA–Cyclen)–Cu was designed and synthesized; this probe is a Cu(Ⅱ) complex that uses Cu(Ⅱ) decomplexation to achieve the sensitive and rapid detection of aqueous H 2 S via the "turn-on" mode. We observed that BA–Cyclen–Cu exhibited good membrane permeability, low toxicity, and lysosome-targeting ability, facilitating H 2 S detection in living cells. Furthermore, we demonstrated the potential biological applications of the probe by measuring exogenous H 2 S originating from Na 2 S and GYY4137, a slow-release donor, and endogenous H 2 S generated via the catalysis of cystathionine- β -synthase in both normal (H9c2) and cancerous (U87) cells. Moreover, BA–Cyclen–Cu was successfully used to detect exogenous H 2 S by the external standard method in fetal bovine serum, the serum of a healthy person, and the serum of a patient with liver cancer. [Display omitted] • BA-Cyclen-Cu displayed high selectivity, sensitivity and fast response toward H 2 S with "turn-on" mode. • BA-Cyclen-Cu have a good performance on exogenous/endogenous H 2 S sensing in cancer cells and normal cells. • BA-Cyclen-Cu was successfully used to detect H 2 S in serum samples. [ABSTRACT FROM AUTHOR]

The aromatic polyketide tetracenomycin X (TcmX) was recently found to be a potent inhibitor of protein synthesis; its binding site is located in a unique locus within the tunnel of the large ribosomal subunit. The distinct mode of action makes this relatively narrow class of aromatic polyketides promising for drug development in the quest to prevent the spread of drug-resistant pathogens. Here we report the isolation and structure elucidation of a novel natural tetracenomycin X congener – 6-hydroxytetraceonomycin X (6-OH-TcmX). In contrast to TcmX, 6-OH-TcmX exhibited lower antimicrobial and cytotoxic activity, but comparable in vitro protein synthesis inhibition ability. A survey on spectral properties of tetracenomycins revealed profound differences in both UV-absorption and fluorescence spectra between TcmX and 6-OH-TcmX, suggesting a significant influence of 6-hydroxylation on the tetracenomycin X chromophore. Nonetheless, characteristic spectral properties of tetracenomycins make them suitable candidates for semi-synthetic drug development (e.g., for targeted delivery, chemical biology, or cell imaging). [Display omitted] • Hydroxylated tetracenomycin X is produced by the Amycolatopsis sp. A23 strain. • 6-Hydroxylation reduces both antimicrobial and cytotoxic activity of tetracenomycin X. • 6-Hydroxylation significantly alters the tetracenomycin X chromophore. • UV–Vis spectra of tetracenomycins are dependent on solvent and pH. • Activity is impaired, but not due to lower protein synthesis inhibition ability. [ABSTRACT FROM AUTHOR]

Although carbon dots (CDs) as a promising fluorescent nanomaterial have been studied for nearly twenty years, excitation-independent long wavelength emission CDs are rarely reported and are highly desirable for biomedical applications. Herein, we show that the excitation-independent, bright-orange-emissive, polyethylenimine-modified CDs (PEI-CDs) can be easily obtained by using 1, 2, 4-triaminobenzene and PEI as precursors through a simple hydrothermal method. PEI-CDs prepared under our experimental conditions are low-toxic and safe, and their cellular uptake can be observed via the red fluorescence of PEI-CDs appearing inside cells. Furthermore, PEI-CDs are able to bind spontaneously small interfering RNA (siRNA) to form the nano-complexes by electrostatic attraction. The PEI-CDs-siRNA complexes can effectively deliver the specific siRNA targeting hepatoma-derived growth factor (HDGF) into human glioblastoma cells, and therefore downregulate the expression of HDGF, which is considered as a potential target for glioblastoma treatment. Thus, the excitation-independent long wavelength emission PEI-CDs may constitute a new siRNA delivery carrier with imaging-trackable ability. [Display omitted] • Excitation-independent, bright-orange-emissive PEI-CDs are obtained. • An improved dialysis-precipitation method is used for purification of PEI-CDs. • PEI-CDs can bind siRNA to form the nano-complexes by electrostatic attraction. • PEI-CDs-siRNA complexes can deliver siHDGF into human glioblastoma cells. • PEI-CDs are a new siRNA delivery carrier with imaging-trackable ability. [ABSTRACT FROM AUTHOR]