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A new colorimetric and fluorescent dual-responsive probe named Rb-SSC was designed and synthesized using Rhodamine B and tripeptide (SerSerCys-NH 2) as raw reactants. The selective recognition properties in detecting 17 metal ions were investigated by UV–Vis spectroscopy and fluorescence spectroscopy in DMF/water (4:6, v/v, 10.0 mM HEPES, pH = 7.4), and the results showed that Rb-SSC had high selectivity fluorescence response and clear colorimetric analysis for trivalent metal ions (Fe3+, Al3+ and Cr3+). These selectivity were attributed to protonation of Rb-SSC , and the K sp value of the trivalent ions promotes the formation of hydrolyzed H+. Additionally, the limit of detections (LODs) were found to be 27.4 nM for Fe3+, 28 nM for Al3+ and 62.3 nM for Cr3+, respectively. In addition, MTT assay and cells experiments showed that Rb-SSC has low toxicity and achieved fluorescence imaging of trivalent metal ions in living cells. What's more, the G/B ratio has a good linear relationship with the concentrations of Fe3+ based on the smartphone sensing platform (RGB values), and the limit of detection (LOD) was as low as 0.37 μM. [Display omitted] • A novel highly selective and sensitive peptide-based probe named Rb-SSC was firstly synthesized. • Rb-SSC was utilized as a multi-responsive probe for the detection of Fe3+, Al3+ and Cr3+ ions. • The detection limits for Fe3+, Al3+ and Cr3+ were calculated to be 27.4 nM, 28 nM and 62.3 nM, respectively. • Rb-SSC was successfully utilized to recognize Fe3+, Al3+ and Cr3+ in living cells. • Smartphone-assisted detection platform could achieve visual assay of different Fe3+ concentrations. [ABSTRACT FROM AUTHOR]

Detecting abnormal levels of folic acid (FA), Fe3+, and Ca2+ in the human body is crucial due to their association with various diseases. Orange peel carbon quantum dots (OP-CQDs) with blue fluorescence (λ ex = 370 nm, λ em = 440 nm) were synthesized using a one-step hydrothermal method when waste biomass orange peel was utilized as the carbon source. An "on-off" fluorescence sensor, referred to as OP-CQDs-FA-Fe3+/Ca2+, was developed for quantitative analysis of the drug FA, as well as the metal ions Fe3+ and Ca2+. Additionally, the sensor was utilized for fluorescence imaging of HepG 2 liver cancer cells, demonstrating its exceptional biocompatibility. The concentration of FA displayed a linear relationship in the range of 5.00–90.00 μmol L−1 and 0.30–2.50 mmol L−1, with a limit of detection (LOD) of 0.15 μmol L−1. The spiked recovery in folic acid tablets ranged from 95.70% to 104.50%. The addition of Fe3+ or Ca2+ leads to a reduction or restoration of the fluorescence intensity in the OP-CQDs-FA system, resulting in an "on-off" sensor mode. The spiked recoveries in human serum samples were 100.15%–100.48% for Fe3+ and 98.05%–98.18% for Ca2+. This study highlights the considerable potential of OP-CQDs for ion detection, drug analysis, and cell imaging. • Environmentally-friendly, low-cost OP-CQDs were synthesized via one-pot hydrothermal method. • OP-CQDs function as "on-off" probes for FA, Fe3+, and Ca2+ detection. • OP-CQDs have been found to have excellent cytocompatibility. • Actual samples can be tested in folic acid tablets and human serum. [ABSTRACT FROM AUTHOR]

Dual-state luminogens (DSEgens) are organic luminescent molecules that exhibit strong emissions in both molecularly dispersed and aggregated states. The introduction of fluorine into organic conjugates has been shown to influence their photophysical properties, but its effect on DSEgens remains unexplored. Herein, we synthesized three naphthalimide-arylimidazole luminogens, namely NIBH , NIBPF , and NIBOF , with fluorinated or nonfluorinated phenyl groups on the pyrrole-like nitrogen. We systematically investigated their photophysical properties using spectroscopic studies, theoretical calculations, and single crystallography. Our results demonstrate that fluorine substitution in DSEgens leads to shortened electronic conjugation, highly twisted molecular conformations, and loose three-dimensional packing arrangements. Consequently, fluorinated DSEgens, such as NIBPF and NIBOF , exhibited a significant spectral blueshift and more pronounced mechanofluorochromic properties compared to the non-fluorinated NIBH. Intriguingly, NIBPF with a para-position fluorine substituent displayed relatively redshifted and stronger emission in tetrahydrofuran solutions, while showing a blueshifted and lower emission in the solid state compared to NIBOF , which has an ortho-position fluorine substituent. These findings confirm the efficacy of fluorine as a small substituent to tune the photophysical properties of DSEgens in both dilute solutions and the solid state. Furthermore, the three bright DSEgens were employed for mechanofluorochromism, trace water analysis, and live-cell imaging applications. • Three naphthalimide-arylimidazole conjugates with DSE properties are synthesized. • These DSEgens vary in fluorine substitution. • Fluorine effect on photophysical properties is systematically investigated. • Fluorine substitution is effective to tune the photophysical properties of DSEgens. • DSEgens show mechanofluorochromism, trace water detection, and live-cell imaging. [ABSTRACT FROM AUTHOR]

A novel environmentally benign synthesis of Zn and Fe based metal organic frameworks (MOFs) of Lawsonia inermis leaf extract prepared in-house by a simple room temperature extraction technique is presented. BET isotherm and HRTEM analyses revealed mesoporous nature of the newly synthesized MOFs [6.4 nm (Zn-NLw), 3.6 nm (Fe-NLw)]. Their potential for host-guest interaction facilitating sensing applications was demonstrated by selective binding of histidine (His) and tryptophan (Trp) recognized from fluorescence. Addition of His and Trp, induced significant changes in the emission maxima of MOFs (at 470 nm) demonstrating their sensing capacity for these molecules. Host-guest interaction was further investigated by electrochemical studies evidenced as a function of variation in oxidation-reduction peaks. Cytocompatibility of the MOFs were assessed by MTT assay, impact on cellular architecture, degree of cellular uptake while their application in cell imaging was investigated by confocal microscopy analysis. The results suggest excellent biocompatibility of Zn-NLw and Fe-NLw in vitro with significant level of uptake by cells. Fe-NLw exhibited time dependent subcellular localization with distinct luminescence characteristics at a short time period of 30 min as well as at 2 h. These results therefore validate the potential application of Zn-NLw and Fe-NLw in biosensing and fluorescence based bioimaging. [Display omitted] • Extraction of lawsone from Lawsonia inermis and synthesis of Zn/Fe MOFs. • Sensing and imaging potential of cytocompatible MOFs. [ABSTRACT FROM AUTHOR]

Realizing highly efficient emission of organic fluorophores in both solution and solid state still represents a challenging task, due to either aggregation-caused quenching (ACQ, requiring relatively low working concentration) or aggregation-induced emission (AIE, requiring relatively high working concentration). Herein, we report a highly efficient fluorophore consisting of a pyrido [1,2- a ]benzimidazole core and a simple twisted phenyl substituent. The planarity of pyrido [1,2- a ]benzimidazole ensures the conjugation thus achieving strong emission in dilute solution (quantum yield: 94.4%). Meanwhile, the π-π stacking induced fluorescence quenching is blocked by the twisted phenyl ring, which leads to efficient emission in the solid state (quantum yield: 95.2%). The compound exhibits high photostability as evidenced by minimal loss of the fluorescence even after 6 h of continuous irradiation in air. More importantly, SKOV-3 cell imaging and anti-counterfeiting application have been realized by using this fluorophore at very different concentrations. Such "twisted structure" design would open new possibilities for development of high-efficiency robust organic fluorophores that can function under a wide range of conditions. [Display omitted] • A highly efficient and photostable organic fluorophore was developed using a simple "twisted structure" design. • The fluorophore shows bright emission in both solution (QY = 94.4%) and solid state (QY = 95.2%). • SKOV-3 cell imaging and anti-counterfeiting application have been realized by at very different concentrations. [ABSTRACT FROM AUTHOR]

Upconversion nanoparticles (UCNPs) have great potential applications in biological imaging, medical treatment and optical sensing. However, the development of an inorganic-organic hybrid fluorescent probe to accurately detect noxious ions and scientifically assess irritation in vivo remains a challenge. Herein, we demonstrate a fluorescent nanoprobe for detecting nitrites (NO 2 −) and assessing the irritation in jellyfish cell. The nanoprobe was assembled by linking neutral red to the surface of polyethylene glycol (PEG) modified NaGdF 4 :Yb,Er@NaYF 4 core/shell nanoparticles. The nanoprobe could efficiently capture the NO 2 − in jellyfish and simultaneously visualize the process. It's known that the intensity ratio of green to red emission (IRGRE) of neutral red modified upconversion nanoparticles increases linearly with the amount of NO 2 − increasing. Moreover, the irritation of NO 2 − was assessed in jellyfish cells using neutral red modified fluorescent nanoprobe based on cell imaging and spectrum signals, that NO 2 − has irrecoverable injury to the cells. This work based on dye-modified upconversion luminescence nanoprobe is expected to shed further light on the biological analysis and detection of ions. [Display omitted] • The diameter of the core/shell NaGdF 4 :Yb3+,Er3+@NaYF 4 :Yb3+ particles is measured to be about 31.5 nm. • The upconversion fluorescence nanoprobe could efficiently capture NO 2 − in jellyfish to detect their excretion in vivo. • The irritation of NO 2 − was assessed in jellyfish cells using neutral red modified fluorescent nanoprobe. • The IRGRE of neutral reds modified upconversion nanoparticles increases linearly with increasing nitrites. [ABSTRACT FROM AUTHOR]

5-formyluracil (5fU) and 5-formylcytosine (5fC) both exist in most cells and tissues. Chemoselective labelling is becoming increasingly crucial for understanding their diverse biological functions. Compared to the Schiff base-type C N ligation, formation of C C based on Knoevenagel or Wittig reaction exhibits higher stability. Moreover, 5fU is more reactive than 5fC, so that reagents with compromised aldehyde activity can realize 5fU specificity, but often require long labelling times. Herein, we found that the one-step synthesized TCF could achieve rapid and selective detection of 5fU, as well as fluorogenic labelling of 5fU-DNA and imaging of intracellular 5fU, based on C C linkage under mild conditions. [Display omitted] • The fastest and selective method for 5fU labeling based on C=C linkage under mild conditions so far. • Aqueous Knoevenagel reaction with TCF was firstly introduced as a bioorthogonal approach to label 5fU-containing DNA with good yield. • The TCF -assisted extension of conjugated system enables fluorescent qualitative and quantitative detection of 5fU and imaging of intracellular 5fU. [ABSTRACT FROM AUTHOR]

We report the synthesis and the investigation on the multi-functional property of a piperazine-modified tetraphenylethene (TPE-Pz). After acidification, the cationic TPE-Pz+ molecules can form stable suspensions in tetrahydrofuran/water mixture solutions and the molecular aggregates are highly emissive due to the aggregation-induced emission property of the tetraphenylethene unit. The experimental results showed that the suspension can be directly used as fluorescent probe for the detection of hazardous chemicals such as aldehydes and picric acid. For aldehydes, the probe exhibited high quenching efficiency (up to 80.90%), high sensitivity and low detection limit (0.05–0.97 μM). The piperazine group allows TPE-Pz to possesses high specificity for lysosome with low cytotoxicity and high contrast in comparison with LysoTracker Red. [Display omitted] ∙Pronounced aggregation-induced emission property due to the TPE unit. ∙Stable aggregates in aqueous solution due to the amphiphilic structure. ∙Directly used as fluorescent probe for the detection of hazardous chemicals in aqueous media. ∙ Lysosome-specific cell-imaging due to the piperazine functional group [ABSTRACT FROM AUTHOR]

A facile synthesis of rare earth (RE3+) activated gadolinium oxide (Gd 2 O 3) decorated on the surface of multiwall carbon nanotubes (MWCNT), i.e., MWCNTs@Gd 2 O 3 : RE3+ (RE = Eu, Tb, and Tm) have been carried out. The X-ray diffraction patterns and scanning electron microscope (SEM) micrographs of as-prepared nanocomposites confirm the homogeneous dispersion of the nanocomposites. The emission spectrum of MWCNTs@Gd 2 O 3 :Eu3+ nanocomposite exhibits the characteristic emission lines of Eu3+ at 590 nm and 610 nm with the radiation of 254 nm. MWCNTs@Gd 2 O 3 :Tb3+ nanocomposite displays an intense green emission at 547 nm, while MWCNTs@Gd 2 O 3 :Tm3+ nanocomposite shows a strong blue emission at 457 nm under ultra-violet (UV) excitation of 360 nm. The calculated values of emission lifetimes in the studied phosphors could attribute to more radiative relaxation. Henceforth, the results affirm that these spectral engineered luminescent materials may envision prospective applications in fluorescent imaging, bio-separation, fluorescent lamps, and display devices, etc. • The photoluminescent MWCNTs@Gd 2 O 3 :RE3+ (RE = Eu, Tb, and Tm) nanocomposite have been synthesized by precipitation approach. • As-synthesized MWCNTs@Gd 2 O 3 :RE3+ offer excellent luminescence properties in the blue, yellow, and red emissions range. • The MWCNTs@Gd 2 O 3 :RE3+ nanocomposite may be useful with the broad prospect in fluorescence imaging and display devices etc. [ABSTRACT FROM AUTHOR]

A facile AIE fluorescent probe which exhibits a large stokes shift of 202 nm has been successfully developed. The probe can recognize Cd2+ with high selectivity by inhibiting ESIPT process, leading to observably blue-shift and significantly enhanced fluorescence with the colour changed from green to cyan. Excitedly, the recognition of Cd2+ is completely free from the interference of Zn2+ and Cd2+ could be quantitatively detected in aqueous solution with the detection limit of 1.5 × 10−7 M. Moreover, the probe has been successfully applied to detect Cd2+ in real water samples and image Cd2+ in living cells. [Display omitted] • A facile AIE fluorescent probe with large stokes shift of 202 nm has been constructed. • The color-conversion from green to cyan during recognizing Cd2+ is on account of the inhibited ESIPT process. • The recognition of Cd2+ is completely free from the interference of Zn2+. • The probe has been successfully employed to detect Cd2+ in real water samples and bioimage Cd2+ in living cells. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is a well known gaseous signal transmitter in physiological and pathological processes. Herein, we developed a near infrared (NIR) fluorescence probe XXMU-H 2 S based on dicyanophosphone derivatives, which was surprisingly found to show high selectivity for H 2 S over various other analytes including biothiols, making it feasible to detect H 2 S in living system. After reaction with H 2 S, this probe showed rapid and significant turn-on NIR emission changes centered at 686 nm within 10 min, a remarkable large Stokes shift (138 nm) and high sensitivity (LOD: 16 nM). Furthermore, the probe has also been successfully applied to imaging of exogenous and endogenous H 2 S in living cells and zebrafish. • A near-infrared turn-on fluorescent probe (XXMU-H 2 S) was developed. • This probe was employed for the detection of H 2 S in living systems. • XXMU-H 2 S showed a high selectivity and sensitivity toward H 2 S with a fast response. • Reaction with H 2 S gave a large Stokes shift and fluorescence intensity enhancement. • XXMU-H2S was used for the in vitro and in vivo detection of H2S. [ABSTRACT FROM AUTHOR]

The green fluorescent protein (GFP) chromophore has been widely applied as a biological marker or viscosity sensor. However, modulation of GFP chromophore for photodynamic therapy (PDT) has rarely been reported. Inspired by this, through the unique phenothiazine-anchored strategy, a near-infrared emission photosensitizer Lys-PtzFP was designed and synthesized to achieve this process. The maximum absorption wavelength of Lys-PtzFP was 460 nm and the corresponding molar extinction coefficient was 6.60 × 104 M−1 cm−1 in MeOH. The maximum emission wavelengths of Lys-PtzFP was at 725 nm. The photosensitizer Lys-PtzFP showed a high singlet oxygen quantum yield (Φ Δ = 0.42) and low fluorescence quantum yield (φ F = 0.002) in MeOH. Besides, Lys-PtzFP possessed high specificity for lysosomes with negligible dark cytotoxicity (MTT assay >94.6%), good photostability and low half-maximal inhibitory concentration (IC 50) of 0.93 μM. Finally, the intracellular photodynamic therapy experiments revealed that Lys-PtzFP can produce singlet oxygen in lysosomes and induce apoptosis under irradiation. In conclusion, Lys-PtzFP could be a promising photosensitizer for PDT and two-photon imaging applications. This type of photosensitizer can inspire the development of new photosensitizers for further explore highly efficient PDT. • Heavy atom-free photosensitizer, Φ Δ = 0.42, IC 50 = 0.93 μM. • Phenothiazine-GFP chromophore with near-Infrared emission of 725 nm. • Two-photon fluorescent imaging. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H 2 O 2) plays an important role in the initiation and progression of many diseases. Therefore, the detection of H 2 O 2 in vivo is very important to elucidate its biological functions in various diseases. At present, the research of fluorescent probes has attracted wide attention. Fluorescent probes are becoming more and more useful as tools for detecting various substances. In this paper, we present a novel fluorescent probe capable of selectively detecting H 2 O 2 in organisms. This probe is based on the design strategy of the recognition of H 2 O 2 enhancing the water-solubility, as a result, producing the turn-on fluorescence intensity. With the increase of hydrogen peroxide concentration, the fluorescence intensity of the newly as-prepared probe is enhanced. There was a good linear relationship when the concentration range of hydrogen peroxide was from 1 μM to 100 μM. In terms of cell imaging work, the detection of endogenous and exogenous H 2 O 2 in RAW 264.7 macrophage cells showed obvious fluorescence enhancement under confocal microscopy. So this new probe has been shown to be a reliable chemical tool for detecting the generation and development of H 2 O 2 -related diseases in living systems. [Display omitted] • The probe that quantitatively and sensitively detect based on the reaction between eater group with H 2 O 2. • The probe displayed prominent selectivity towards H 2 O 2 with low detection limit. • The probe was used to track endogenous and exogenous H 2 O 2 fluctuations in living cells and zebrafish. [ABSTRACT FROM AUTHOR]

Non-traditional intrinsic luminescence (NTIL) have presented many unique properties, which are quite different from traditional fluorescent materials. In this work, using non-aromatic amines, we found three distinct fluorescent peaks at 400 nm, 440 nm and 500 nm, respectively, in a concentration increasing process. The direct proofs obtained from NMR and other techniques suggested that these peaks might originate from different concentration-dependent aggregates. On the other hand, our results well explained the weird phenomena that NTIL systems presented the excitation-dependent fluorescence (EDF) or excitation-independent fluorescence (EIF) in various cases. We proposed a strategy to prepare fluorescent systems with unique property of tunable emission and controllable EDF or EIF, which would be useful in multi-color imaging applications. • For amine-containing NTIL systems, three concentration-dependent fluorescent peaks were firstly detected, which varied from one to another in a "peak-jump" mode. • Simple aliphatic amines (i.e., TETA) were adopted to prove that the fluorescence might originate from three kinds of concentration-dependent aggregates. • Our results explained the prolonged puzzle that amine-containing NITL systems presented the excitation-dependent/independent fluorescence in different circumstances. • A strategy was proposed to explore applications of multi-color fluorescent imaging based on the unique properties of NTIL. [ABSTRACT FROM AUTHOR]

A novel probe T - 1 for the response of NTR based on fused four-ring quinoxaline skeleton was investigated. Under the action of NTR, the probe produced green fluorescence response at 495 nm. The spectroscopic properties, response mechanism, fluorescence imaging, and other aspects of probe T - 1 were investigated. In the fluorescence titration experiments, the probe showed excellent selectivity, lower detection limit (41 ng/mL) and better fluorescence quantum yield (Y u = 0.14) for NTR. The response mechanism of the probe was explained by the comparison of F - 1 ultraviolet spectra obtained in two different ways and the verification of HRMS spectra. Additionally, the application of fluorescence imaging technology made it possible to detect endogenous NTR, and broadened the application prospect of fluorescent probe. We have designed a novel probe T - 1 for the response of NTR based on fused four-ring quinoxaline skeleton. Probe T - 1 showed excellent selectivity, lower detection limit (41 ng/mL) and better fluorescence quantum yield (Y u = 0.14) for NTR. The application of fluorescence imaging technology made it possible to detect endogenous NTR, and broadened the application prospect of fluorescent probe. [Display omitted] • The probe T - 1 can detect NTR with high sensitivity and selectivity. • The detection limit is as low as 41 ng/mL with high accuracy. • The probe shows low toxicity and is successfully employed to monitor NTR in vivo. [ABSTRACT FROM AUTHOR]