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Light is indispensable to every aspect of our life. It is also a very important component of photodynamic therapy to cure cancer. Photodynamic therapy is a modern and effective technique among all these prevailing anticancer therapies because of its uniqueness in selectivity. Organometallic complexes are seen to be better candidates for photodynamic therapy. Cyclometalated complexes have been developed for targeting cellular organelles with remarkable photoactivity. Different types of metal complexes can display PDT activity. Considering its photophysical characteristics, the iridium complex is the most effective alternative to use as a PDT agent. Iridium-based cyclometalated complexes have shown decent results as a PDT-active anti-cancer agent. Reactive oxygen species (ROS) and singlet oxygen with high singlet oxygen quantum yield are both extremely capable of being produced by complexes. High cytotoxicity has been exhibited by various Iridium-based cyclometalated complexes in the presence of light and negligible cytotoxicity in dark conditions. These complexes are considerably fluorescent with the capability of cellular imaging and have displayed very significant potency against HeLa, A549, MCF-7, and other various cell lines. Complexes can arrest the different paths of the cell cycle through different mechanisms and help to force cellular apoptosis. Hence, a galore of organelle-targeted cyclometalated iridium complexes has been showcased in this review article. • Summarizing Current Research: This review papers provide an overview of existing literature on a particular topic. It summarizes the current research and advancements in the field of photodynamic therapy using cyclometalated iridium complexes. • Identifying Trends and Gaps: By analyzing various studies, the review can identify trends in research, such as the most effective types of complexes or promising targeting strategies. It highlights gaps in knowledge or areas where further research is needed. • Consolidating Information: Research in the field of photodynamic therapy using cyclometalated iridium complexes may be scattered across various journals and publications. This review paper consolidates this information into one place, making it easier for researchers and clinicians to access and understand. • Informing Future Research Directions: This review paper can suggest future research directions or areas that warrant further investigation. This can help guide researchers in their studies and experiments. • Educational Resource: This review paper serves as a valuable educational resource for students, researchers, and practitioners. It provides an in-depth understanding of this specific topic and can be used as a reference in academic settings. • Impact on Clinical Practice: Ultimately, the goal of research in this area is to develop more effective treatments for various diseases, such as cancer. This review paper highlights the promising cyclometalated iridium complexes for photodynamic therapy that could have a direct impact on clinical practice by informing the development of new therapeutic strategies. [ABSTRACT FROM AUTHOR]

Nitroreductase (NTR) is overexpressed in hypoxic tumor cells, which is closely related to inflammation, tumorigenesis, tumor invasion and metastasis. Therefore, developing fluorescence probes for detecting intracellular NTR sensitivity has great significance for diagnosis and treatment of tumors. Therefore, we designed a novel fluorescent probe (Pro-CN) based on julolidine skeleton for the detection of NTR. The probe could discriminate rapidly NTR from other biological species like sulfhydryl compounds and some ions. Meanwhile, a fine linear relationship between fluorescence intensity of the probe and NTR consistence has been observed with a very low detection limit of 4.4 ng/mL. In addition, Pro-CN was successfully applied in imaging endogenous NTR in Hela cells and living zebrafish. The excellent performance of the probe makes it have great potential for monitoring NTR in complex biological systems, and it also provides the possibility of its application in human health, disease diagnosis and treatment. [Display omitted] • Probe Pro-CN exhibits a turn-on fluorescence for sensing NTR. • Pro-CN is highly sensitive to sense NTR with a very low detection limit of 4.4 ng/mL. • Pro-CN was successfully applied for imaging endogenous NTR in living Hela cells and zebrafish. [ABSTRACT FROM AUTHOR]

Ferroptosis is a distinctive iron-dependent and GSH-related cell death form, and has been demonstrated to closely relate with Golgi apparatus (GA). Exploring the fluctuations of GSH level in GA during ferroptosis is of great importance for the deep research of biological functions of GA in ferroptosis. Herein, we reported a novel GA-targeting probe (NA-G) for the detection of GSH in GA during ferroptosis. The probe NA-G utilized N-oxidized pyridine sulfonyl as a responsive site for GSH, with tetradecanoyl amide serving as GA-targeting moiety. NA-G exhibited remarkable sensitivity and selectivity, manifesting a heightened response to GSH and effectively visualizing GSH through bright green fluorescence under UV light. By fluorescence imaging of cellular GSH, NA-G was demonstrated to serve as a GA-targeting probe, and could successfully monitor the dynamic changes in intracellular GSH. Further experimentation revealed that NEM stimulation resulted in the removal of a significant amount of endogenous GSH in GA, and erastin-induced ferroptosis significantly reduced GSH levels in GA. Notably, we discovered that Fer-1 and VE effectively inhibited the substantial depletion of GSH in GA during ferroptosis. [Display omitted] • A Golgi apparatus-targeting probe (NA-G) for revealing the fluctuations of GSH during ferroptosis was developed. • The probe NA-G could be used to image endogenous GSH in Golgi apparatus of living cells. • Erastin-induced ferroptosis could decrease GSH level in Golgi apparatus of living cells. • Fer-1 and VE were demonstrated to efficiently inhibit the depletion of GSH during ferroptosis. [ABSTRACT FROM AUTHOR]

Ammonia is a common toxic gas in industrial and agricultural production, which will cause harm to the environment and human health in certain extent. Here, a novel fluorescent probe (R)- 1 based on 1,1′-binaphthol (BINOL) was synthesized for real-time, on-site and quantitative detection of ammonia. The mechanism study shows that the functional groups of –CHO and –OH on (R)- 1 interact with ammonia, which changes the electronic state of the probe molecule and excites strong fluorescence. A test strip for rapid detection of ammonia was developed, which changed from light yellow to reddish brown under natural light after interacting with ammonia, thus realizing the rapid detection and easy visualization of ammonia. Meanwhile, bioimaging experiments shows that probe (R)- 1 can detect exogenous ammonia in cells. [Display omitted] • Specific selective fluorescence recognition of ammonia. • Fast response time (300 s) and high sensitivity (0.96 ppm). • A test strip for real-time and visual detection of ammonia. • Exogenous ammonia fluorescence imaging of cells. [ABSTRACT FROM AUTHOR]

The multiphoton absorbing (MPA) materials have been extensively investigated due to their crucial merits of long wavelength excitation and short wavelength emission, of which the organometallic complexes are the most promising but still challenging candidates for developing efficient MPA materials. Herein, a novel cyclometallated iridium complex (abbreviated as SQ) is reported as a multiphoton absorption phosphorescent probe, which is constructed by coordinating the central metal Ir with diethoxyphenyl terpyridine, phenyl pyridine and SCN ligands. The single crystal of SQ exhibits a twisted octahedral structure that can avoid phosphorescence quenching caused by π-π stacking, and the push-pull electron effect of the ligand endows SQ with excellent nonlinear optical (NLO) properties under near-infrared excitation. As a result, two-photon imaging with deep tissue penetration depths is realized at the excitation wavelength of 750 nm. Meanwhile, the planar conjugated structure of diethoxyphenyl terpyridine facilitates the insertion of SQ into base pairs of mitochondrial DNA (mtDNA), thus limiting the intramolecular rotation. Consequently, the emission intensity of the SQ solution enhanced approximately 10-fold after mtDNA was introduced, which led to mtDNA-specific recognition. Our work proves a new way of designing a phosphorescence probe that can specifically identify mtDNA, thus realizing dynamic monitoring of mitochondria. • A novel cyclometallated iridium complex has been synthesized. • The complex was studied by single crystal and multi-photon emission spectra. • The mechanism of specific binding of the complex to mtDNA was revealed. • mtDNA-specific recognition and two-photon bioimaging of complex were investigated. [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]

A multicolor phosphorescence supramolecular system was constructed based on the complexation of amphiphile (G) and cucurbit[8]uril (CB[8]). The guest G which was composed of hydrophobic coumarin and hydrophilic phosphor 6-bromoisoquinoline can aggregate in water and form large nanosheets accompanying bright fluorescence at 390 nm. After encapsulated by CB[8], the aggregation was prohibited and formed nanosheets with smaller size and the fluorescence peak at 390 nm decreased, meanwhile a phosphorescence peak at 550 nm appeared. Upon the adding of lower-rim dodecyl-modified sulfonatocalix[4]arene (SC4AD), the aggregation was disrupted and particles were formed which were a few 10s of nanometers in size. Subsequently, a stepwise high efficient phosphorescence energy transfer system with a variety of colors was constructed with rhodamine B (RhB) and Sulfo-Cyanine 5 (cy5)/Si-rhodamine (SiR) as acceptors. Finally, the multicolor phosphorescent supramolecular assembly was used to near-infrared cell imaging. [Display omitted] [ABSTRACT FROM AUTHOR]

Chromenoxanthenes are colorful dyes which do not suffer from any fluorescence turn-off induced by spirocyclic forms as usually observed for conventional rhodamine and fluorescein xanthene analogues. In that way, wide variety of applications in particular in bioimaging can be foreseen for those underexplored fluorophores. Herein, a one-pot synthesis of rhodol-like chromenoxanthene dyes is reported, which are further modified at the periphery of the core structure to tune the optical properties. Resulting neutral derivatives are bright fluorophores in the orange-red spectral window, while cationic counterparts are almost non-emissive. These optical properties are fully characterized and are also rationalized via first-principles calculations. In particular, the occurrence of twisted intramolecular charge transfers is shown to account for the dark-state quenching occurring in the charged compounds. This feature is harvested in the construction of an activity-based fluorescent probe for mitochondria imaging. Excellent organelle localization is achieved, while the emission signal is proportional to the hydrogen peroxide concentration in the mitochondria. Furthermore, the absence of cytotoxicity bestows rhodol-like chromenoxanthene dyes a bright future in cellular imaging applications. [Display omitted] • An innovative one-pot synthesis of rhodol-like chromenoxanthene dyes is reported. • The chromenoxanthene core is converted to an activity-based fluorescent probe for mitochondria imaging. • Detailed computational studies are conducted to understand the optical properties of the probes. • Bio-imaging studies are done in melanoma cancer cells. [ABSTRACT FROM AUTHOR]

Ratiometric probes are favored for their application in biological systems, and the signal ratio between two channels is a crucial indicator for evaluating the performance. Since changing the substituent group on the recognition group would significantly influence the response performance of a fluorescent probe, in this work, we modified the substituent group on the 7-position of a coumarin to give two Hg2+ probes based on through-bond energy transfer (TBET) strategy; the probes displayed a much higher detection capacity and emission ratio between the red and blue channels. The probes were successfully applied for Hg2+ imaging in cells and living mice and possess significant bacteriostatic activity, demonstrating potential application in biological science, but also present excellent stability and detection ability serving as solid-phase detection materials via fabricating into nanofiber using electrostatic spinning. [Display omitted] • TBET-based Hg2+ probes were constructed with LOD low to 2.7 nM. • Better response performance was achieved by modifying the recognition group. • Living cells and mice detection suggest good bioimaging ability. • The probes possess good bacteriostatic activity due to their lactam structure. • The probes were fabricated into nanofiber test strips via electrospinning. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) exerts its therapeutic effects by inducing apoptosis, necrosis, and microvascular damage in tumor cells, but it also causes inflammation and induces the expression of angiogenic factors, accelerating tumor metastasis and proliferation. In this study, aggregation-induced emission (AIE) photosensitizer (PS) for PDT was combined with the cyclooxygenase-2 (COX-2) inhibitor indomethacin (IMC) for cancer-selective imaging and more efficiency in inducing apoptosis in cancer cells. In detail, inhibition of COX-2-mediated AIE PS effectively targeted the Golgi apparatus (GA) of cancer cells to generate large amounts of reactive oxygen species (ROS) in situ, thereby exerting a PDT effect. Specifically, COX-2 and other key enzymes that trigger inflammation and metastasis were significantly inhibited. It had more potent anti-tumor activity (tumor inhibition rate of 64.32 %), as well as anti-metastatic and anti-proliferative effects compared to the use of usual AIE PS. [Display omitted] • TTPI was obtained by combining AIE-PS with the COX-2 inhibitor indomethacin. • TTPI precisely targeted COX-2 in the Golgi with high co-location coefficient. • PDT while inhibiting enzymes that trigger inflammation and metastasis such as COX-2. • The inhibition rate of TTPI in vivo was significantly increased to 64.32 %. [ABSTRACT FROM AUTHOR]

The tertiary structures of HSA and BSA show a 76 % similarity, and the abnormal levels of HSA in body fluids can cause many diseases. Therefore, accurate quantification of HSA and effectively distinguishing HSA from BSA have significant application value in various fields. In this paper, a deep-red fluorescent probe, NITH , based on 1,8-naphthalimide, is demonstrated as a potential tool for accurately quantifying HSA and distinguishing HSA from BSA. The probe not only exhibits large stokes shift (100 nm) and low detection limit (4.61 μg/L, 0.0692 nM), but also effectively detects HSA by entering its hydrophobic cavity and emitting red fluorescence. Furthermore, NITH is capable of tracking the distribution levels of HSA within the cells through endogenous and exogenous cellular imaging. The application of NITH spans various environments such as cells, zebrafish, urine, and test strips, solidifying it as an effective tool for HSA detection. [Display omitted] • NITH has been synthesized by introducing benzothiazole sulfonate at the 3-position of 1,8-naphthalimide. • NITH can effectively distinguish HSA from BSA. • NITH can quickly identify, detect and track HSA in bioimaging. • NITH can be successfully applied in test strips, urine, cells and zebrafish imaging. [ABSTRACT FROM AUTHOR]

The present study highlights the development, identification, and solvent-regulated chemosensing property of a Schiff base chemosensor (E)-2-(2-((5-chloro-2-hydroxybenzylidene)amino)propyl)-3′,6′-bis(diethylamino)spiro[isoindoline-1,9′-xanthen]-3-one (RBAS). The Schiff base RBAS is developed by the simple condensation of 5-chloro salicylaldehyde and rhodamine-1,2 diamino propane derivative (RBAP). Interestingly this probe can optically as well as fluorometrically exhibit pH sensor activity and the spirolactam ring opening and the conversion from enol to keto form in lower and higher pH regions respectively are the main key factors to show pH sensor activity. Several spectroscopic, Dynamic Light Scattering (DLS), and scanning electron microscopy (SEM) studies confirm the AIE active property of the probe in 2:8 DMSO-water and ethanol-water mediums where the probe exhibits strong luminescence properties. Interestingly in ethanol-water and DMSO-water medium, it can detect Hg(II) via turn-on and off fluorescence respectively. Actually, in different solvent mediums, the presence of Hg(II) plays a crucial role in the spirolactam ring opening and closing of the developed probe. Simultaneously in an ethanol-water medium, it can detect picric acid by turning off fluorescence. By using mass and NMR spectrum analysis, the 1:1 stoichiometric addition of the probe and target analytes has been verified and the density functional theory (DFT) study is implemented in optimizing the probe-analyte structure. The live cell imaging study gives the approval of the biosensing ability of the probe. Impressively the probe can be successfully used to detect Hg(II) in real soil samples. [Display omitted] • Development and spectroscopic identification of a novel rhodamine-based chemosensor (RBAS). • RBAS can be effectively used as pH sensor and spirolactam ring closing or opening controls the pH sensors performance. • DLS, SEM, UV and fluorescence probes the AIE effect of RBAS in two different mediums. [ABSTRACT FROM AUTHOR]

Four novel tridentate scaffolds IP-nTPA (n = 1, 4, 8, and 12), in which 2,6-bis(imidazo [1,2-a]pyridin-2-yl)pyridine and alkoxyl-substituted triphenylamine (TPA) are utilized as electron-donor and electron-acceptor, respectively, have been synthesized. Due to the inclusion of flexible alkoxyl chain to suppress π–π stacking in solids, IP-nTPA (n = 1, 4, 8) displayed efficient fluorescence in both solution and solid state. Meanwhile, IP-nTPA demonstrated an obvious solvatochromism with red-shifted emission when increasing solvent polarity, which is associated with the formed intramolecular charge transfer (ICT) states in the donor-acceptor (D-A) architecture. Theoretical calculations and single crystal structure analysis were utilized to interpret the emission behaviors in both solution and solid state. Importantly, IP-4TPA was chosen as the candidate to exhibit reversible acidichromism, metal ions detection, and information security application. Finally, the bioimaging application of IP-nTPA in PC-3 cells was investigated, which showed excellent biocompatibility and cell permeability. Four D-A type DSE tridentate scaffolds IP-nTPA (n = 1, 4, 8, and 12) have been synthesized with promising applications in acidichromism, metal ions detection, data encryption, and bioimaging. [Display omitted] • Four C4-alkoxyl-substituted tridentate fluorophores IP-nTPA have been synthesized and characterized. • IP-nTPA exhibited DSE properties through combination of D-A structure and self-isolation strategy. • IP-4TPA exhibited reversible acidichromism, metal ions detection, and information security application. • Bioimaging application of IP-nTPA in PC-3 cells was investigated with excellent biocompatibility and cell permeability. [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]

Lysosomes and lipid droplets (LDs), as two crucial sub-organelles within cells, play a pivotal role in maintaining the normal cellular functions. However, rational design and synthesis of fluorophores that selectively target specific organelles still pose a challenge. Herein, we developed a series of eight fluorescent dyes (LCA1-LCA4 and LCN1-LCN4) containing morpholine moiety, which effectively targeting lysosome and LDs within cells through rational regulation of substituents in the molecular structure. Among these compounds, compounds LCA1 / LCN1 containing triphenylamine group and LCA3 / LCN4 containing coumarin group exhibit specific targeting towards the LDs, whereas compound LCN2 containing carbazole group demonstrates targeted localization to lysosome. Moreover, these five compounds displayed the advantages of high cellular viability, excellent resistance to interference, pH insensitivity and the ability to enter cells without washing. Compounds LCN2 and LCA1 are capable of real-time monitoring the dynamic behavior of lysosome and LDs respectively, as well as the mitophagy (LCN2) or the number and diameter variations of LDs (LCA1). The results provide a potential candidate for specific lysosomes and LDs imaging. [Display omitted] • Eight fluorescent dyes containing morpholine moiety have been rationally regulated to target different organelles. • Compounds LCA1, LCA3 , LCN1 and LCN4 are capable of targeting LDs via wash-free procedure. • LCN2 with carbazole group could rapidly targeting lysosomes within 20 s without any washing step. • LCN2 enables real-time monitoring the dynamic process of lysosomes and mitophagy. • Compound LCA1 can be applied to tracking the dynamic behaviors and variation (number and diameter) of LDs. [ABSTRACT FROM AUTHOR]

Single benzene-based fluorophore (SBBF) is a representative small-size fluorescent dye which has an electron push-pull structure within a benzene backbone. In this work, we disclosed a new amino-SBBF (ASBBF) library that has various alkyl-amines and aromatic-amines on the electron-donating site. The synthesis, photophysical properties, quantum chemical calculation, two-photon responsiveness, and bioimaging applicability of ASBBF in cells were successfully identified. We believe that our present work provides a guide to the development of new fluorescent materials and molecular probes in various research fields. [Display omitted] • The amino-SBBF (single benzene-based fluorophore) library was disclosed. • The synthesis and basic photophysical properties of the amino-SBBF library were identified. • The bio-imaging capabilities of amino-SBBF were confirmed. [ABSTRACT FROM AUTHOR]

As a class of heterocyclic compounds, 1,3,5-Triazines have a wide range of applications in degradable materials, drug synthesis, fluorescent dyes, etc. In this paper, donor-acceptor, π-conjugated 1,3,5-triazine dyes (TzAr-R) were successfully synthesized from 1,3,5-triazine and benzaldehyde derivatives, and their photophysical properties were studied. On this basis, two typical probes (TzAr-OH and TzAr-NapOH) were selected for in-depth study, and found to have the advantages of pH resistance, high selectivity, good viscosity response and low cytotoxicity. Furthermore, TzAr-OH and TzAr-NapOH exhibited excellent performance in cell viscosity detection and monitoring liquid food spoilage, indicating that the probes could be used as powerful imaging tools in the fields of biomedicine and food safety detection. [Display omitted] • A class of 1,3,5-Triazines based fluorescent dyes were constructed and their photophysical properties were studied. • Two typical probes (TzAr-OH and TzAr-NapOH) exhibited good advantages of pH resistance, high selectivity, good viscosity response and low cytotoxicity with large Stokes shifts. • TzAr-OH and TzAr-NapOH showed excellent performance in cell viscosity detection and monitoring liquid food spoilage. [ABSTRACT FROM AUTHOR]

A new hemicyanine-based near-infrared "off-on" recognition Cu2+ fluorescent probe NRh-NP was designed and successfully synthesized. The structure of NRh-NP was characterized by NMR, ESI-HRMS and single crystal X-ray diffraction analysis. NRh-NP has high sensitivity, selectivity and a low limit of detection (33 nM as fluorescence sensor and 35 nM as UV sensor) to Cu2+. According to Job's plot and ESI-HRMS, the coordination ratio of NRh-NP to Cu2+ was 1:1. DFT theoretical calculations proved that the sensor mechanism was photo-induced electron transfer (PET). More importantly, NRh-NP has excellent membrane permeability and low cytotoxicity, which could be used not only for the detection of Cu2+ in human breast cancer cells (MCF-7), but also for imaging Cu2+ in living mice. [Display omitted] • The structure of NRh-NP was characterized by NMR, ESI-HRMS and single crystal X-ray diffraction analysis. • The responses of NRh-NP toward Cu2+ were fully proved by Job's plot, ESI-HRMS and DFT theoretical calculations. • NRh-NP has high sensitivity and selectivity with detection limit as low as 33 nM. • NRh-NP can be used for Cu2+ imaging in living cells and in vivo. [ABSTRACT FROM AUTHOR]

The functional materials with aggregation-induced emission (AIE) feature have been extensively explored for biomedical applications, however, the synthesis of AIE-active functional materials with biodegradable potential and controlled drug delivery behavior have been seldom demonstrated. In this work, we reported for the first time that AIE-active fluorescent cyclomatrix polyphosphazene spheres (named as QM-HCCP-PEG) can be facilely fabricated via a one-step nucleophilic substitution to conjugate hexacyclotriphosphazene (HCCP), amino modified polyethylene glycol (PEG-NH 2) and an AIEgen (QM-OH). The resultant QM-HCCP-PEG shows amphiphilicity and can be capable of self-assembling into spheres with high water dispersibility and desirable fluorescence performance. During self-assembly, antitumor drug bortezomib (BTZ) can be encapsulated in the core of QM-HCCP-PEG with a relative high drug loading capacity up to 12.2%. In vitro drug release profile showed that the micelles could successfully release BTZ in physiological solution. Moreover, the QM-HCCP-PEG displayed excellent biological imaging ability for its outstanding AIE feature and BTZ-loaded nanospheres exhibited significant cytotoxicity against MDA-MB-231 cells. Thus, this work provides new perspective for fabrication of AIE-active functional materials via a convenient and highly efficient experimental procedure and the resultant AIE-active functional materials are of great potential as fluorescent probes and drug delivery vehicles. [Display omitted] • One-pot synthesis of AIE-active fluorescent cyclomatrix polyphosphazene spheres. • AIE-active fluorescent cyclomatrix polyphosphazene spheres were used for delivery BTZ. • BTZ shows pH dependent release behavior. • AIE-active fluorescent cyclomatrix polyphosphazene spheres for cell imaging. [ABSTRACT FROM AUTHOR]

Irreversible damage to the cell membrane is extremely detrimental to the cell. The synthesis of near-infrared (NIR) aggregation-induced emission luminogens (AIEgens) for high-fidelity imaging of cell membranes and the induction of cancer cell necrosis through photo-driving is a desirable option for tumor treatment, but it remains challenging. In this study, a fluorescent probe molecule (ACTP-1) with an amphiphilic structure and AIE properties was designed and prepared. ACTP-1 can effectively bind with 1,2-dioleo- sn -glycerol-3-phosphatecholine or sensitively detect changes in viscosity in a solution and then emit strong red fluorescence in the first NIR window. Due to its specific embedding of the phospholipid bilayer, the rotational motion of the ACTP-1 molecule was suppressed and the luminescence property was activated, resulting in high resolution and excellent photostability for imaging the cell membrane. Furthermore, ACTP-1 , which exhibits a high absorption coefficient in the visible region, can rapidly produce reactive oxygen species (ROS) when exposed to white light. Experiments in cell biology have shown that ACTP-1 can effectively disrupt the cytoskeleton through photodynamic therapy (PDT), leading to cell necrosis instead of apoptosis. This highlights its dual functionality as both a reliable imaging agent and a phototherapy agent. [Display omitted] • Multifunctional photosensitizer (ACTP-1) was designed and prepared. • ACTP-1 can image cell membranes in high fidelity. • ACTP-1 rapidly generates reactive oxygen species under white light irradiation. • Photoinduced ACTP-1 is highly effective in causing cell membrane lysis. • ACTP-1 induces necrotic death rather than apoptosis of cancer cells through PDT. [ABSTRACT FROM AUTHOR]

A protein structure-dependent probe (OTB) for human serum albumin (HSA) was designed. Molecular simulation were used to assist probe design. OTB exhibited favorable selective HSA sensitivity and strong HSA binding ability. As a cationic molecule, OTB could form a stable amphipathic complex with water-soluble pillar [5]arene (WP5). More interestingly, the WP5-OTB complex possessed better HSA responsiveness and stronger HSA binding ability than OTB. The detection limit (3σ/k) of WP5-OTB towards HSA was determined to be 0.33 μM. WP5-OTB complex possessed excellent anti-interference ability in the selective recognition of HSA. Common commercial drugs, fluorescent amino acids, and fatty acids had almost negligible effect on the HSA responsiveness of the complex. The WP5-OTB complex self-assembled into supramolecular fluorescent probe in aqueous solution, and the supramolecular probe possessed favorable HSA-induced bioimaging property, pH-sensitive drug delivery property, and photodynamic activity. [Display omitted] • A cationic ICT probe OTB was designed by fully considering its interaction with HSA. • OTB exhibited favorable serum albumin sensitivity and strong HSA binding ability. • The WP5-OTB complex possessed better HSA responsiveness and binding ability than OTB. • The WP5-OTB complex self-assembled into supramolecular fluorescent probe in solution. • The supramolecular probe had good bioimaging and chemo-photodynamic therapy properties. [ABSTRACT FROM AUTHOR]

A series of hydroxy thiophene-conjugated benzothiazole derivatives (HTB s) was prepared to investigate their fluorescence emission behaviors and capability to selectively stain subcellular organelles for fluorescence imaging. The HTB derivatives exhibited excited-state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT) behaviors, according to their molecular structure. Subtle changes in the molecular structure of the HTB influenced its response to changes in the surrounding environment, such as the solvent polarity and/or pH. In vitro cellular imaging experiments revealed that HTB A (5-(benzo[d]thiazol-2-yl)-[2,2′-bithiophen]-4-ol) could selectively stain mitochondria. In contrast, HTB B -CO 2 Et (ethyl 5'-(benzo[d]thiazol-2-yl)-3′-hydroxy-[2,2′-bithiophene]-5-carboxylate), which contains a regioisomeric hydroxy thiophene unit with an electron-withdrawing ethyl ester group, showed the capability to stain lipid droplets (LDs) in living cells. When the hydroxyl group in HTB B -CO 2 Et was protected with a benzyl group, effective staining of LDs in live cells was achieved. Thus, we successfully obtained an effective fluorescent probe. Collectively, the results indicated that small structural changes resulted in substantial changes in the intracellular localization and in vitro imaging ability of the prepared compounds. [Display omitted] • Hydroxy thiophene-conjugated benzothiazole derivatives (HTB s) were synthesized. • HTB s exhibited polarity-dependent bright emission due to ESIPT and ICT. • The structural change of HTB s enabled selective staining of mitochondria and lipid droplets. [ABSTRACT FROM AUTHOR]

In this paper, several novel nitrogen-containing heterocycle dyes 1a-c with large conjugated planar structures based on naphthyridine derivatives were designed and synthesized, which had excellent optical properties and biological applications. Optical test showed the maximum absorption wavelengths of 1a-c were in the range of 443–485 nm, while the maximum emission wavelengths located at 523–610 nm in difference solvents. Furthermore, they exhibited polarity related fluorescence intensity changes with high fluorescence quantum yields, even up to 88% (1a in THF). Moreover, the transient absorption spectra revealed the excited-state lifetime of dye 1a became shorter with the increase of solvent polarity. Density functional theory calculations are also used to help explain the effect of the polarity of solvents on their fluorescence properties. Interestingly, the dyes 1a-c were somewhat toxic to cancer cells, while had an obvious growth-promoting effect on normal cells. Additionally, 1a-c with excellent lipid droplet (LD) targeting could be used for long-term observation of targeted cellular lis) hysiological activity and further applied to dynamic monitoring of changes in LDs polarity stimulated by TLR4 activator (LPS) in living cells. Overall, the excellent optical properties and biocompatibility of 1a-c indicate that they can serve as fluorescent probes for biological applications, and the results have important implications for understanding the physiological functions of LDs, especially in terms of morphological and polar changes. [Display omitted] • The dibenzo[c,f] [2,7]naphthyridine skeleton have been first applied in the field of cell imaging. • Dyes 1a-c possess high fluorescence quantum yield and excellent polarity response. • Dyes 1a-c are somewhat toxic to cancer cells, while have a growth-promoting effect on normal cells. • Dyes 1a-c can sensitively target lipid droplets with a low concentration, and dynamically monitor their polarity changes. [ABSTRACT FROM AUTHOR]

This study reported a unique mitochondria-targetable phosphorescent 'on-off-on' probe, Ir-DPA, based on an iridium(III) complex derivative for the sequential and specific detection of Cu2+ and Cys in vitro and in vivo. Probe Ir-DPA was constructed by a lipophilic cation unit as the chromophore as well as the mitochondria biomarker and a dipicolylamine (DPA) group as the recognition unit for Cu2+, followed by removal of Cu2+ specifically in the presence of Cys. The probe itself was strongly emissive at 570 nm. Upon addition of Cu2+, marked quenching occurred as result of the binding of Cu2+ with DPA moiety of this probe, accompanied by a distinct naked-eye luminescence color change from orange yellow to colorless. Additionally, further addition of Cys, the displacement of Cu2+ from in situ generated Ir-DPA-Cu ensemble because of the large nucleophilicity of cysteine toward Cu2+ led to the release of probe, giving rise to the luminescence recovery, as well as a relevant chromogenic change from colorless to orange yellow. Ir-DPA showed a large Stokes shift of 200 nm and high selectivity and sensitivity for the rapid detection of Cu2+ and Cys under physiological conditions, with low detection limits of 0.04 μM and 1.21 μM for Cu2+ and Cys, respectively. More importantly, the probe successfully targeted mitochondria, sensitively detected Cu2+ and exogenously or endogenously generated Cys both in mitochondria of living cells and zebrafish. Finally, Ir-DPA was capable of quantifying Cu2+ level in water samples and the in situ generated ensemble identifying Cys in human serum. These results indicated the great potential of Ir-DPA for monitoring Cu2+ and Cys in environmental, biological systems, and mitochondrial processes. A mitochondria-targetable phosphorescent 'on-off-on' probe for sequentially and selectively detecting Cu2+ and cysteine has been achieved based on Cu2+-displacement reaction. [Display omitted] • A mitochondria-targetable phosphorescent 'on-off-on' probe for the specific detection of Cu2+ and cysteine was developed. • The probe exhibited a sequential orange yellow-colorless-orange yellow phosphorescent response to Cu2+ and cysteine. • The probe was successfully used for imaging Cu2+ and cysteine both in mitochondria of living cells and animals. [ABSTRACT FROM AUTHOR]

Traditional β-diketones are rarely used as fluorescent emitters. Here, two novel triphenylamine-modified β-diketonate derivatives containing either a furan or thiophene unit (TPA-DK-O and TPA-DK-S) have been designed, synthesized and fully characterized. Both of the emitters have D-A type configuration, and show abnormal dual-state emissive characters with high quantum efficiency both in dissolved and aggregate state owning to rational design strategy. Additionally, owing to their molecular conformational flexibility and inherent intramolecular charge transfer characteristics, TPA-DK-O and TPA-DK-S show intriguing optical features such as solvatochromism, vicosity-dependent fluorescence and temperature response characteristics. The solvatochromism is derived from the intramolecular charge transfer effect which is confirmed by density functional theory calculation and fluorescence in solvents of different polarities. These unique optical properties of TPA-DK-O and TPA-DK-S are expected to be utilized for detecting local viscosity, polarity of system and temperature sensing. Moreover, the excellent dual-state emissive characters of TPA-DK-O are utilized for chemical sensors and cell imaging. The metal ion detection experiments indicated that TPA-DK-O has a fluorescence response capability to Fe3+ and Mg2+, and has a good linear relationship in the concentration range of 48–800 μM and 0–30 μM for Fe3+ and Mg2+, respectively. The cell incubation experiments shows that TPA-DK-O has low toxicity and good biocompatibility for cells. The cell imaging experiments reveals that TPA-DK-O not only stains and images cells, but also responds to Fe3+ in living cells. Making a contrast between TPA-DK-O and TPA-DK-S, it is found that replacing furan with thiophene in the β-diketonate derivatives showed slight effects on optical properties. [Display omitted] • ICT strategy was used to create β-diketonate derivatives with DSE characteristics. • Two DSE dyes that are used in cell imaging and metal ion sensing. • The molecular design principle for DSE characteristics is provided. [ABSTRACT FROM AUTHOR]

The successful synthesis of organoboron complexes with novel core structures facilitates the development of new functional dyes. In this context, synthesizing stable seven-membered organoboron complexes poses substantial challenges, so dyes of this type have seldom been studied. The successful synthesis of a series of pyrrole hemithioindigo-derived organoboron complexes is reported. The photophysical properties have been analyzed, and the results have been compared to those predicted by rigorous theoretical calculations. The presence of a seven-membered ring N,O boron-chelated moiety in these complexes was definitively confirmed by single crystal X-ray diffraction studies. Confocal laser experiments demonstrated the ability of one of the complexes studied to effectively permeate HeLa cells and selectively stain the cytoplasmic region. The reported synthetic strategy provides a framework for synthesizing a wide range of versatile organoboron dyes and opening up new avenues for developing innovative materials. [Display omitted] • Pyrrole hemithioindigo-derived organoboron complexes were designed and fully characterized. • Theoretical calculations were employed to disclose the structure-property relationships. • Cellular imaging of the dye was studied by confocal laser imaging. [ABSTRACT FROM AUTHOR]

SO 2 , the fourth endogenous gaseous signaling molecule, plays an important role in cells. Besides, SO 2 derivatives are used as preservatives in food and drinks. To understand the level of SO 2 derivatives in body and food, we developed a FRET-based fluorescent probe CPO. CPO had high energy transfer efficiency and high selectivity toward SO 2 derivatives. It could fast respond toward SO 2 derivatives in an aqueous solution (3 min) and possessed a low detection limit (68 nM). Furthermore, the SO 2 derivatives in tap water, sugar, vermicelli and cells were detected by probe CPO. In addition, probe CPO had a high colocalization coefficient (0.95) for lipid droplets. [Display omitted] • A novel FRET-based water-soluble fluorescent probe for fast response to HSO 3 − was reported. • The probe had good sensitivity and selectivity to HSO 3 −. • The probe was applied to detect HSO 3 − in tap water, food and cells. • The probe preferred to load on lipid droplets with a high Pearson's coefficient. [ABSTRACT FROM AUTHOR]

The abnormality of Cys concentration in organism could lead to a series of diseases, so its effective detection is of great importance in disease diagnosis. Here we developed a novel ESIPT fluorescent probe HBT-IDAc based on the classic ESIPT fluorophore 2-(2′-hydroxyphenyl)benzothiazole (HBT) and indanone, which could selectively and sensitively detect Cys with a large Stokes shift up to 210 nm and the detection limit to 0.89 μM. In addition, the probe exhibited good anti-interference and low cytotoxicity, and has been successfully applied to monitor Cys in cells. • A novel ESIPT fluorescent probe for selective and sensitive detection of Cys was developed. • The probe has the large stokes shift (210 nm) and good LOD (0.89 μM) in aqueous environment. • The probe exhibits low cytotoxicity and has been applied for imaging Cys in cells. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is a vital gas signaling molecule that performs crucial physiological functions in biological systems, and it can also cause food safety problems. In this study, we developed a cyanine derivative-based mitochondrial-targeted near-infrared fluorescent probe PC-H 2 S for detecting H 2 S. When PC-H 2 S reacted with H 2 S, it reached maximum fluorescence intensity at 656 nm and detection limit as low as 34 nM, and exhibited strong chromogenic response from green to red for H 2 S. Moreover, PC-H 2 S could be utilized to identify H 2 S generated during food spoilage and thus monitored the process of food spoilage. More significantly, PC-H 2 S showed excellent mitochondrial targeting capabilities and endogenous/exogenous H 2 S imaging of living cells and zebrafish could be performed. As a result, this research provides an attractive method for detecting H 2 S in food and biological systems and has potential value in physiopathological research. [Display omitted] • A cyanine derivative-based mitochondrial-targeted NIR fluorescent probe PC-H 2 S for detecting H 2 S was developed. • PC-H 2 S had a low detection limit and exhibited strong chromogenic response from green to red for H 2 S in naked eyes and UV light. • PC-H 2 S test strips was capable of monitoring H 2 S produced by food spoilage. • PC-H 2 S could be used for living cells and zebrafish imaging. [ABSTRACT FROM AUTHOR]

Developing fluoran dyes for fluorescent material is significant but challenging because they are notorious for terrible luminescent efficiency. In this manuscript, two fluoran dyes (F3 and F4) were synthesized by the introduction of thiazole and indazole into the fluoran skeleton, which showed colored and fluorescent spirolactone opening form in a wide pH range (F3 : 1–10, F4 : 1–13). In addition, the absorption and emission spectra of methyl esterification products F3Me and F4Me showed large Stokes shifts (over 75 nm) in water and achieved an improved fluorescence quantum yield of 30.1% in CHCl 3. Based on the dye F4Me, a new fluorescent probe F4HP was developed, which showed high selectivity and high sensitivity (LOD of 2.0 nM) to copper ions in H 2 O/CH 3 CN (v/v, 3/2) system. Moreover, the sensing experiment was allowed in the pH range of 4.0–7.5. Furthermore, the F4HP exhibits suitable cell cytotoxicity and can be applied for imaging intracellular copper ions by confocal fluorescence imaging technology. Thiazole and indazole functionalized fluoran dyes were prepared with improved fluorescence and application in the construction of a novel copper-selective and sensitive fluorescent probe. [Display omitted] • Two modified fluoran dyes were prepared with stable fluorescence in water. • F4Me achieved a fluorescence quantum yield of 30.1% in CHCl 3. • A novel probe F4HP for Cu2+ was prepared with high selectivity and sensitivity. • F4HP could be employed as a tool for imaging intracellular Cu2+. [ABSTRACT FROM AUTHOR]

Mercury ion (Hg2+) is highly toxic to the environment and organisms, therefore, monitoring and quantitative detection of Hg2+ is of great significance. In this work, a new fluorescent probe TPEH that integrated tetraphenylethene (TPE) and 2-(2 ′ -hydroxyphenyl)benzothiazole was designed and synthesised. In EtOH/HEPES (2:8, v/v, pH = 7.2) solution, TPEH displays fluorescence turn on detection of Hg2+ with the advantages of swift response (<100 s), high selectivity and strong disturbance-resistant, a large Stokes shift (220 nm), and low limit of detection (81.7 nM). The sensing mechanism was proved to be Hg2+-triggered releasing of the aggregation-induced emission (AIE)-active precursor compound 2. TPEH has been successfully applied to detect Hg2+ in seafood and tea, and image Hg2+ in living cells. In addition, TPEH can be used to detect the content of Hg2+ in actual water samples with the aid of smartphone. [Display omitted] • A new AIE-based fluorescent probe TPEH for Hg2+ detection has been developed. • TPEH has the advantages of rapid response (<100 s), a large Stokes shift (220 nm), and a low detection limit (81.7 nM). • TPEH can detect Hg2+ in seafood and tea, and image Hg2+ in living cells. • TPEH can detect Hg2+ in actual water samples with the help of smartphone. [ABSTRACT FROM AUTHOR]

The fluorescent probe with both aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) shows significant advantages, such as no self-quenching at high concentration, large Stokes shift, high selectivity towards analyte etc. Based on tetraphenylethene and ESIPT structural modules, three AIE-ESIPT molecules containing one different atom (S, O, N) have been constructed in this paper. The effects of three atoms on the optical properties of fluorescent molecules have been investigated by fluorescence spectroscopy and X-ray crystallographic analyses. Interestingly, the cyclic detection of HCl and NH 3 gases can be achieved with the BTY-TPE -based portable test paper. In addition, BOY-TPE and HBIY-TPE can detect ClO− by naked eye with low detection limit, good biocompatibility. Three AIE-ESIPT fluorescent probes respectively containing S, O, N atoms have been synthesized. The effects of S, O, and N atoms on the optical properties of fluorescent molecules have been investigated by fluorescence spectroscopy and X-ray crystallographic analyses and DFT calculation. The results indicate that all three exhibit AIE and ESIPT properties, X-ray crystallographic analysis indicate a significant difference in molecular packing, which should be the dominant factor in the polymorph dependence of ESIPT luminescence. It is interesting to note that BTY-TPE -based test paper can be used for cyclic detection of HCl and NH 3 gases. In addition, BOY-TPE and HBIY-TPE can be used as intracellular probes for detecting ClO−.[ [Display omitted] ] • Three AIE-ESIPT double-mechanism fluorescent crystals have been synthesized. • Effects of S, O, and N on the properties of three fluorescent crystals were discussed. • BTY-TPE -based test strip could repeatable detect HCl and NH 3 gases. • Both BOY-TPE and HBIY-TPE with extremely low detection limit for detecting ClO−. • Both BOY-TPE and HBIY-TPE could detect ClO− in living cells. [ABSTRACT FROM AUTHOR]

Herein, we designed a potent ClO− probe named ETMC , which exhibited aggregation-induced emission (AIE) characteristic in solid state and water/EtOH binary solvent. Probe ETMC exhibited an colormetric from yellow to blue and ratiometric response to ClO− with high selectivity and sensitivity, and a low detection limit of 3.66 × 10−7 M. Moreover, probe ETMC could be applied to visibly and quantitatively detect the different concentraction of ClO− in test paper. Importantly, probe ETMC could effectively detect endogenous and exogenous ClO− in living A549 cells by an outstanding ratio signal change. Also, the sensing mechanism of probe ETMC for ClO− was confirmed by FT-IR, 1H NMR, HRMS, DLS, TEM and DFT calculation. In this work, probe ETMC, which exhibited aggregation-induced emission (AIE) characteristic in solid state and water/EtOH binary solvent was developed and could effectively detect endogenous and exogenous ClO− in living A549 cells by an outstanding ratio signal change. Also, the probe ETMC has been successfully applied in visibly and quantitatively detection the different concentraction of ClO−. [Display omitted] • A fluorescent probe ETMC with AIE effect was developed, which exhibited an colormetric and ratiometric response to ClO−. • The probe ETMC could be applied to visibly and quantitatively detect the different concentraction of ClO− in test paper. • The probe ETMC could detect endogenous and exogenous ClO− in living A549 cells by an outstanding ratio signal change. [ABSTRACT FROM AUTHOR]

Aggregation-induced emission luminogens (AIEgens) provide a new approach to address the aggregation-induced quenching (ACQ) defect prevalent in traditional fluorescent dyes. Since there are only two dispersion forms of single molecule (monomer state, weak fluorescence) and aggregates (multimer state, strong fluorescence) in aqueous medium, most of the reported AIEgens exhibit a single emission band and therefore cannot be used for dual-channel fluorescence imaging in living cells. In this work, the "monomer-dimer-multimer" dispersion mechanism was innovatively introduced into the design of dual-emission AIEgens. Under the guidance of this concept, two cyanovinyl-pyrene dual-emission AIEgens with twisted molecular configuration have been readily synthesized and studied by theoretical calculations, UV–visible absorption, steady-state fluorescence, time-resolved fluorescence, dynamic laser scanning (DLS) and laser confocal imaging. These AIEgens emit weak fluorescence in monomer state due to intramolecular C C rotation. With gradual aggregation, they form dimer state to emit blue fluorescence centered at 460 nm, and then convert into multimer state to emit red fluorescence around 570 nm, simultaneously exhibiting AIE and dual-emission characteristics. They also have excellent photostability, good membrane permeability and low cytotoxicity. Confocal imaging tests demonstrate that AIEgens composed of cyanovinyl-pyrene and benzimidazole moieties is available for dual-channel imaging in Hela cells and macrophages cells, and shows great potential in designing ratiometric nanoprobe. Our design mechanism will provide a versatile platform for the development of dual-emission AIEgens. • "Monomer-dimer-multimer" dispersion mechanism was used to design dual-emission AIEgens. • Two dual-emission AIEgens were synthesized and studied. • They have excellent photostability, good membrane permeability and low cytotoxicity. • Cyanovinyl-pyrene-benzimidazole AIEgens show potential in dual-channel imaging and ratiometric sensing in cells. [ABSTRACT FROM AUTHOR]

Five BODIPY derivatives containing different number of styryl units were designed and synthesized based on the Knoevenagel reactions. All compounds were characterized by NMR and HRMS. The single crystal structures of compounds 1 and 3 – 5 were confirmed by X-ray crystallography. The photophysical and electrochemical properties of these dyes were also investigated by UV/Vis spectroscopy, fluorescence spectroscopy, and cyclic voltammetry. Our study indicates that the optical and electronic properties of the BODIPY derivatives could be easily tuned by the introduction of a various number of styryl units. Their absorption and emission spectra become gradually bathochromically shifted from the red region to the near-infrared region. Their first reduction and first oxidation potential (HOMO-LUMO gap) changes from 2.45 to 1.62 V. The structure-optical property relationships of these compounds are also systematically studied. Furthermore, cellular uptake experiments suggest that compounds 1 – 3 are membrane permeable and promising fluorophores for bio-labeling/imaging applications. • Five BODIPY derivatives containing different number of styryl units were synthesized. • The structure-optical property relationships are systematically studied. • Compounds 1 – 3 show excellent cell membrane permeability, and can be utilized as cell fluorescence imaging. [ABSTRACT FROM AUTHOR]

Strategically modified4-(diethylamino)-2-(pyridin-2-ylmethoxy)benzaldehyde appended BODIPY-based probe N,N-SP-BPY detects aspartic acid (Asp) and glutamic acid (Glu) by inhibition of Photoinduced electron transfer (PET) process in water. The probe shows considerable and rapid fluorescence enhancement upon addition of Asp and Glu. Additionally, a distinct colorimetric change from pink to a colorless solution can be observed to recognize traces of Asp and Glu. The probe detects Asp and Glu as low as 1 μM and 5 μM respectively. Furthermore, the probe can efficiently detect intracellular Asp and Glu in live HeLa, A549, MDA-MB-468 and HEK-293T cells under fluorescence microscope without showing any cytotoxic effect. Two model BODIPY derivatives are also synthesized to establish strategic modification. 1H NMR titration and theoretical calculations strongly supports experimental findings. Image 1 • A highly selective BODIPY probe, N,N-SP-BPY detects aspartic acid (Asp) and glutamic acid (Glu) in water. • 'Turn On' fluorescence can be observed by inhibition of Photoinduced Electron Transfer (PET) process. • A distinct colorimetric change from pink to colourless solution can be observed to recognize Asp and Glu. • N,N-SP-BPY efficiently images intracellular Asp and Glu in live cells under fluorescence microscope. [ABSTRACT FROM AUTHOR]

The deficiency and excess of Fe3+ will lead to biological disorders and even many diseases. So, measuring the levels of Fe3+ in human body has drawn great attentions for health monitoring. Fluorescence method has been broadly applied because of high sensitivity, real-time detection and intracellular imaging. In this work, a new lipidic conjugated polymer, poly[3-{2-[2,5-Bis-(2-ethyl-hexyloxy)-4-propenyl-phenyl]-vinyl}-9-butyl-6-methyl-9H-carbazole] (PBMC), has been synthesized and used to prepare the conjugated polymer nanoparticles (CPNs-PBMC) by coprecipitation with poly (styrene- co -maleic anhydride) (PSMA). The CPNs-PBMC exhibited large Stokes shift (141 nm), small average diameter (43.96 nm), low toxicity and excellent photostability. Meanwhile, the CPNs-PBMC was highly sensitive to Fe3+ and has a lower detection limit of 0.63 nmol/L. The sensing mechanism was based on aggregation-induced fluorescence quenching of CPNs-PBMC in the presence of Fe3+ because of chelation and electrostatic interaction. Furthermore, the critical micelle concentration was measured by fluorescence method. More interestingly, the fluorescence of CPNs-PBMC could be circularly quenched and recovered using Fe3+ and EDTA, which may supply a possible control by logic gate. Furthermore, the fluorescence imaging showed that CPNs-PBMC could detect Fe3+ in living cells. A new lipidic conjugated polymer (PBMC) has been synthesized and used to prepare the conjugated polymer nanoparticles (CPNs-PBMC) by coprecipitation with PSMA. The CPNs-PBMC exhibited large Stokes shift (141 nm), small average diameter (43.96 nm), low toxicity and excellent photostability, and could detect Fe3+ with high sensitivity (LOD = 0.63 nmol/L) based on aggregation-induced fluorescence quenching (AIFQ). Moreover, the fluorescence of CPNs-PBMC could be controlled by logic gate using Fe3+ and EDTA. Finally, CPNs-PBMC was successfully applied to Fe3+ detection in living cells by confocal imaging. Image 1 • The CPNs-PBMC exhibited large Stokes shift (141 nm). • The CPNs-PBMC was highly sensitive to Fe3+ and has a lower detection limit of 0.63 nmol/L. • The CPNs-PBMC detected successfully Fe3+ in living cell. • The fluorescence of CPNs-PBMC could be controlled by logic gate using Fe3+ and EDTA. [ABSTRACT FROM AUTHOR]

The bis-binaphthol-pyrene derivative 1 (R isomer) and 2 (S isomer) selectively sense Zn2+ by undergoing a reversible fluorescent emission enhancement at 550 nm. Moreover, upon addition of Zn2+, the magnitude of the peak in the CD spectrum of 1 at 289 nm increases and the intensity of the peak at 272 nm decreases. Opposite changes were observed for 2 upon the addition Zn2+. The distinctive fluorescence and ratiometric CD spectral changes are attributed to a change in the dihedral angle between the binaphthol groups in 1 and 2 caused by Zn2+ binding. Probe 1 was further employed to image Zn2+ in cells. Image 1 • The bis-binaphthol-pyrene derivative 1 and 2 selectively sense Zn2+. • The distinctive fluorescence and ratiometric CD spectral changes were observed upon the addition of Zn2+. • Probe 1 (R isomer) and 2 (S isomer) displayed opposite CD spectral changes with Zn2+. • Probe 1 was employed to image Zn2+ in cells. [ABSTRACT FROM AUTHOR]

Herein, a two-photon mitochondria-targeting fluorescent probe (TPNP) which can be activated by the azo reductase (AzoR) has been developed for imaging the hypoxic microenvironment of tumors in vivo. The probe TPNP showed a low detection limit (LOD = 1.85 eq), high selectivity, and considerable steadiness in different pH conditions (3.0–11.0). In living cells, it could co-locate with the commercial dye in the mitochondria (co-localization coefficient: 0.92) and indicate hypoxia in both one-photon and two-photon fluorescence imaging. Its AzoR-activation mechanism was further verified by the docking simulation as well as the experiments of adding AzoR or electron transporter inhibitors. Moreover, the in vivo real-time fluorescence imaging proved that TPNP could monitor hypoxia and the tumor progression in mouse tumor models. Overall, this designed probe exhibited high sensitivity, synthetic ease, and excellent fluorescent properties, which might therefore enlighten new ideas for the diagnosis of tumors in future studies. • A new hypoxia-sensitive fluorescent probe (TPNP) for tumor detection is reported. • TPNP exhibited high sensitivity, synthetic ease, and impressive fluorescent properties. • TPNP can monitor the presence of solid tumors in the xenograft mice model. [ABSTRACT FROM AUTHOR]

Replacement of electron-donating N,N -dialkyl groups with four-membered azetidine has recently been used as a promising approach to improve low fluorescent quantum yields of coumarin. Herein, we report the synthesis of 7-cycloalkylamino/alkyl amino analogues (6 – 19) from 4-methyl umbelliferone-derived nonaflate (1a') using Buchwald-Hartwig amination and comparison of their fluorescence activity with 7-azetidinyl-4-methylcoumarin (4). The absolute quantum yields of cyclobutylamine (7), cyclopentylamine (8), propylamine (10) , butylamine (11), isopropylamine (16), and isobutylamine (17) were found to be comparable to that of the azetidine (4) coumarin. Further, the dyes were found to be biocompatible in cell lines. Also, the successful application of these new dyes in biological imaging for living cells has been demonstrated. • 7-cycloalkylamino/alkyl amino analogues of 4-methyl umbelliferone were synthesized using Buchwald-Hartwig amination. • Photophysical studies of synthesized analogues were performed. • The application of these new dyes in cell imaging was demonstrated. [ABSTRACT FROM AUTHOR]

In this study, a pH-sensitive fluorescent probe was created through the host-guest assembly of an amphiphilic hydroxyphenyl benzotriazole derivative (HBT-11) and cucurbit[7]uril (CB7). The fluorescence of HBT-11 is highly dependent on the molar ratio (r) of CB7 to HBT-11. If r < 1, the peak positions remain unchanged while the intensity increases with r. If r > 1, the emission peaks shift to longer wavelengths. The complexation also results in a shift in the p K a of HBT-11. The 1:1 mixture of CB7 and HBT-11 has a p K a close to neutral pH. The supramolecular probe allows for discrimination of malignant A549 and benign HEK 293T cells owing to a pronounced 8-fold light-up effect in malignant A549 cells attributed to the pH-responsive fluorescence. Given that the selective light-up mechanism is based on the pH-sensitive fluorescence of the supramolecular probe, this approach is expected to be applicable to other cancer cells. [Display omitted] • A pH-sensitive supramolecular fluorescence probe was constructed. • The fluorescent intensity of the probe was greatly enhanced as pH < p K a. • The probe was applied to discriminate malignant and benign cells. [ABSTRACT FROM AUTHOR]

The general mechanism of chemotherapeutic resistance is related to changes in the uptake and efflux rate of chemotherapeutic drugs or intracellular transport. In the progress of photodynamic and PTX combination therapy, the excessive use of photosensitizers (PSs) may cause side effects. Since PSs are exposed to light, they can still cause ongoing damage to normal cells. To effectively reduce this side effect, we propose a strategy to regulate the concentration of PTX in resistant cells using low concentrations of AIEgen PSs. In this work, the molecular structure of four AIEgen PSs (TPEPy , TPECPy , TPAPy , and TPESPy) were designed and synthesized featuring different "D−π−A" type structures. They displayed excellent optical properties, good biocompatibility, good PDT effect, mitochondrial targeting and cell imaging. Among these AIEgen PSs, TPESPy exhibited the strongest PDT effect in tumor cells and PTX resistant tumor cells. The reversal coefficient of PTX resistant tumor cells can be achieved as 2214. In addition, to demonstrate the transport mechanism of PTX within tumor cells, we further study the effect of uptake and expel PTX in the PTX resistant SKOV-3 cells. The results show the rate of uptake and expel PTX for PTX resistant SKOV-3 cells can be effectively changed by controlling the concentration of AIEgen PSs and light irradiation time, providing precise treatment options for drug-resistant tumor cells. • Developing Red/NIR AIEgen PSs with different singlet oxygen generation efficiency. • The modulation of HOMO-LUMO and ΔEst energy gap can obtain better AIEgen PSs. • AIEgen PSs have a good photodynamic effect on drug-resistant tumor cells. • Low level of PSs can regulate the uptake and expel rate of PTX by tumor cells. [ABSTRACT FROM AUTHOR]

Mitochondria and lysosomes play important roles in maintaining normal cellular metabolism; thus, visualizing their morphology, structure, and interactions in living cells at the nanometer scale is essential for further understanding their functions. However, this remains challenging because of the current limitations of fluorescent probes, including poor photobleaching resistance, low biocompatibility, and lack of multi-organelle targeting. Herein, we report the development of biocompatible nitrogen-doped carbon dots (CNDs) with long excitation wavelengths, stable fluorescence, and dual-organelle targeting capabilities. The CNDs enter cells predominantly via energy-dependent transport (including clathrin- and caveolae-mediated endocytosis) and free diffusion and subsequently target the interior mitochondria and lysosomes; furthermore, they enable the stimulated emission depletion imaging of these organelles in living cells with resolutions of up to 134 and 55 nm, respectively. This study provides practical guidance for designing dual-organelle targeting fluorescent probes for the dynamic super-resolution imaging of cellular systems. The nitrogen-doped carbon dots (CNDs) with Long-wavelength excitation for the visualization of lysosomes and mitochondria in the stimulated emission depletion imaging (STED) of live HeLa cells. [Display omitted] • N co-doped CNDs with green fluorescence are successfully synthesized. • CNDs have high fluorescence stability and long-wavelength excitation. • CNDs can target the both the mitochondria and lysosomes in the living cell. • CNDs were suitable as probes for STED imaging of mitochondria and lysosomes. [ABSTRACT FROM AUTHOR]

Fluorescent probes sensitive to microenvironments have constantly been attractive, due to their significant benefits in monitoring changes in the pathophysiological microenvironment and their use in the early detection of associated disorders. In this work, we explored three new molecular rotors that could be potential candidates for detecting lipid droplets (LDs) in cancer cells based on coumarin derivatives connected with electron-donating polycyclic units including, tetraphenylethylene (LD-TPE), pyrene (LD-PYR), and 4,5-diphenylimidazole (LD-DIP). Gratifyingly, LD-PYR showed exceptional polarity and viscosity sensitivity and demonstrated bright fluorescence in highly viscous environments due to the suppression of the twisted intramolecular charge transfer (TICT) phenomenon and intramolecular rotation. Moreover, microenvironment-guided specific LD bioimaging by LD-PYR exhibited a reasonable ability to distinguish between cancer and noncancer cells. These data suggested that LD-PYR has interesting clinical diagnostic and microenvironment-related biological applications. [Display omitted] • Highly polarity and viscosity-sensitive fluorescence probes have been introduced. • LD-PYR probe shows bright fluorescence in a lipophilic environment due to TICT suppression. • LD-PYR demonstrates good biocompatibility in both cancer cell and normal cell lines. • LD-PYR can selectively image lipid droplet in cancer cells. [ABSTRACT FROM AUTHOR]

Human serum albumin (HSA) is considered to be a diagnostic index of numerous diseases, and detecting HSA in subcellular environments is of great importance. In this work, we successfully synthesized a fluorescent probe NDIC based on hydrazide Schiff base, which can self-assemble into nanospheres in aqueous solution and produce distinct fluorescence signal in the presence of HSA. NDIC showed advantages including good sensitivity (LOD = 8.44 nM), high selectivity and anti-interference (over different coexisting proteins, amino acids, cations and anions). Job's plot, CD spectra, HSA destruction, site binding replacement and molecular docking provided reliable evidence for the fact that NDIC could combine at drug site I of HSA. Non-toxic probe NDIC could be applied to quantitatively detect HSA contents in urine, and achieve cancer identification by HSA imaging in cancer cells. More importantly, successful confocal experiment proved that NDIC possessed the lysosome selective imaging ability with the aid of HSA. These results showed the probe NDIC met the requirements of biological applications and was expected to explore HSA at the subcellular levels. • Self-assembled nanoprobe NDIC showed advantages including good sensitivity, high selectivity and anti-interference. • NDIC could be applied to quantitatively detect HSA in urine samples. • Cancer identification was implemented by cell imaging of HSA with non-toxic NDIC. • NDIC possessed the lysosome selective imaging ability with the aid of HSA. [ABSTRACT FROM AUTHOR]

To develop the construction of small organic fluorophores with full color-tunable luminescence through facile synthesis is highly imperative for applications. Herein, novel quinazolinone based BF 2 complexes (2a-2g) have been designed and synthesized. By modifying the structure of quinazolinone ligand, the synthesized boron difluoride dyes exhibited fluorescence in the almost full-color range of the visible spectrum (∼450–750 nm) both in solution and solid-state with good to excellent quantum yield. The influence of three electron donating substituents, such as methyl, methoxy and N,N -dimethylamino group, in quinazolinone core on the photophysical properties of BF 2 compounds was discussed. The position of substituent in quinazolinone has some influence on the emission efficiency, but has little influence on the absorption and emission of BF 2 compounds. Finally, 2g showed good cell compatibility and living cell imaging property. [Display omitted] • A novel quinazolinone-based BF 2 fluorescent dyes have been synthesized. • The BF 2 dyes exhibited fluorescence in full-color range (∼450–750 nm) both in solution and solid-state. • The highest solution fluorescence QY up to 0.99, the QY in solid state up to 0.50 • 2g showed bright deep red to NIR fluorescence in B16 cells. [ABSTRACT FROM AUTHOR]

As a signal molecule, SO 2 plays an important role in the process of cell metabolism. The abnormal level of sulfur dioxide will induce many diseases of human body. Viscosity is an important index of lysosome. Abnormal lysosome viscosity can also lead to many diseases. Therefore, we have developed a new fluorescence probe PAPD for simultaneous imaging of sulfur dioxide derivatives and lysosomal viscosity. The probe realizes rapid detection of HSO 3 − based on Michael addition reaction mechanism. At the same time, with the increase of viscosity, intramolecular rotation is inhibited, thus the probe shows sensitive fluorescence enhancement. In addition, the results of the co-localization experiments show that PAPD has good lysosomal targeting ability. Further studies show that PAPD can be used as a dual-responsive fluorescence probe for SO 2 and viscosity in lysosomes. PAPD can monitor the changes of sulfur dioxide derivatives and viscosity sensitively at the same time, and can well locate in lysosomes. [Display omitted] • A NIR fluorescent probe PAPD was developed for detecting the SO 2 derivatives and viscosity in lysosomes. • PAPD towards HSO 3 − represented excellent selectivity, anti-interference, photostability, and thermal stability. • PAPD was applied for sensing viscosity, endogenous and exogenous HSO 3 − in cells. [ABSTRACT FROM AUTHOR]

Herein, a feasible strategy to enhance the water solubility of potential anti-tumor drugs was utilized, which was to combine hydrochloric acid or sulfuric acid into its molecules. In order to increase drug targeting, three different types of Eudragit® (stomach soluble, enteric soluble and permeable) was used to encapsulate these two salt under mild reaction conditions to obtain six kinds of nano polymer complexes. In order to simulate the gastrointestinal environment, spectroscopic tests were conducted on nanoparticles in PBS buffer solutions with different pH values. The micromorphology of the six complexes was analyzed by TEM. The results showed that the potential drugs were uniformly dispersed in the drug carrier materials, and the particle size was 100–500 nm. The Zeta potential test showed that the complexes had positive stability. The confocal microscope imaging experiments were carried out in different channels of HCT-116 and LO2 cells. The results showed that the complexes had favorable biocompatibility and imaging properties. The calculation of Pearson coefficient showed that some complexes could enter the nucleus. The cell proliferation toxicity test (CCK8) experiment and the TEM experiment of cell uptake localization showed that the complex had definite anti-tumor activity and low cytotoxicity, and the distribution of the complexes was detected in the nucleus and cytoplasm. In vivo imaging experiment, strong fluorescence intensity of the compounds was detected in the subcutaneous tumor tissue of mice. The release of six compounds had the potential of slow and controlled release, and could be well targeted to the stomach of mice. Therefore, potential salt curcumin derivatives are ideal potential anti-tumor prodrugs, and the resulting nanoparticles are suitable for delivery in organisms. [Display omitted] • The hydrochloride and sulfate anti-tumor fluorescent agents were successfully prepared and encapsulated with Eudragit®. • TEM showed that the particles were spherical or dispersed. The distribution of complexes and autophagy were observed in organelles and nuclei. • Cell imaging showed that the six complexes could partially enter the nucleus, and CCK8 experiment showed that the complexes had anti-tumor activity. • In vitro drug release experiments showed that the compound had the potential of controlled release, and complexes were detected in the stomach of mice. [ABSTRACT FROM AUTHOR]

Abstract Fluoride recognition and sensing via artificial receptors have attracted a great deal of attention since it plays an important and indispensable role in biological and environmental processes. Herein, a novel colorimetric and fluorescent chemodosimeter (3-triisopropylsilylflavone 1) based on 3-hydroxyflavone framework has been rationally designed and synthesized for selective recognition towards fluoride. As confirmed by UV–vis and fluorescence techniques, the fluorescent probe 1 exhibited a highly sensitive and selective as well as rapidly responsive (20 s) recognition towards fluoride with a large Stokes shift of 180 nm. The detection limit was deduced to be 0.68 μM, which is much lower than the limit concentration level in drinking water specified by USEPA. The distinctive sensing mechanism is attributed to fluoride-triggered desilylation reaction on the cleavage of Si O bonds, leading to the strong excited-state intramolecular proton transfer emission of 3-hydroxyflavone. In addition, test strips experiment based on the sensor demonstrated the excellently practical feasibility of 1 to sense fluoride even in ppm level. Moreover, the probe is cell permeable and can be capable of reliably detecting fluoride in living cells. Graphical abstract The first colorimetric and fluorescent chemodosimeter based on 3-hydroxyflavone framework has been rationally designed and synthesized for selective recognition towards fluoride in the field of flavone chemistry. Image 1 Highlights • A novel fluorescent chemodosimeter 1 for selective recognition towards fluoride has been designed and synthesized. • It presents the first chemodosimeter for selectiverecognition towards fluoride in the field of flavone chemistry. • The probe 1 exhibited a highly sensitive and selective as well as a rapidly responsive recognition towards fluoride. • The probe 1 is cell permeable and can be capable of reliably detecting fluoride in living cells. [ABSTRACT FROM AUTHOR]

Abstract The detection of cysteine (Cys) is of great significance ascribed to its important role in physiological and psychological process. This paper reported a new fluorescent probe CBFA with red emission signal, which can be prepared through a simple method and exhibited potential application value. Solution experiments demonstrated that the probe revealed high selectivity towards Cys in spite of the interference of its two analogues, homocysteine (Hcy) and glutathione (GSH). And the sensitivity indicated that the probe was suitable for Cys detection in living cells. Furthermore, the recognition mechanism was confirmed to be a concerted reaction including Michael addition and intramolecular cyclization by high resolution mass spectrometer (HRMS) and high-performance liquid chromatography (HPLC). Besides, CBFA showed favorable pH adaptability in biological conditions and low cytotoxicity. Finally, CBFA was successfully applied to selectively imaging Cys in living MCF-7 cells with good cell permeability. We hope this probe will bring some help to the diagnosis of Cys-related diseases. Graphical abstract Image 1 Highlights • A new fluorescent probe for cysteine detection with red emission signal. • Preparing process of the probe was rather simple. • Sensitivity of the probe was satisfactory for Cys detection in living cells. • Endogenous Cys imaging in living cells with high selectivity and sensitivity. [ABSTRACT FROM AUTHOR]