Sensitive Fluorescence Research Articles

Bifunctional MOFs Nanozyme with Peroxidase Activity and Stimulus-responsive Fluorescent for Determination of Glyphosate.

Establishing a fast and simple method for determining glyphosate (Glyp) is crucial for safeguarding the environment and protecting human well-being. In this work, a copper benzenedicarboxylate (CuBDC) metal-organic frameworks (MOFs) with peroxidase-like property and stimulus-responsive fluorescent was prepared by binding Cu2+ with terephthalic acid (TA). The presence of Glyp can coordination with Cu2+ ion and block the peroxidase-like properties of CuBDC, thereby suppressing the catalysis the oxidation of TA into fluorescent product 2-hydroxyterephthalic acid (HTA). Based on these facts, a simple, rapid and sensitive fluorescence detection strategy for Glyp was developed. The fluorescence decreases linearly in the 0.5-10µg/mL Glyp concentration range, and the limit of detection was calculated to be 23.99 ng/mL. Furthermore, the dual-functional CuMOFs-based label-free strategy was effectively employed for detecting Glyp in river water samples. With good performance and practicability, this strategy provides a potential application in the convenient and reliable determination of Glyp in the environment.

CRISPR/Cas12a-mediated fluorescent aptasensor based on DNA walker amplification for oxytetracycline detection

Nowadays, although most oxytetracycline (OTC) are used only in animals, their leaching into the environment and residues in food lead to noticeable health problems. Fortunately, by studying the molecular dynamics of OTC aptamers and the mutations of key bases, aptamer’s base fragments involved in identifying OTC was confirmed for the first time, which provided theoretical guidance for the ingenious design of aptamer detection. Thereafter, benefiting from the amplification impact by DNA walker, the disadvantage of low efficiency caused by CRISPR/Cas12a was effectively avoided. In the established delicate aptasensing platform, small quantity of OTC promoted DNA walker to produce a massive of activators, which stimulated the trans-cleavage activity of CRISPR/Cas12a. By implying nanoclusters (NCs) with covalent organic framework (COF), the sensitive fluorescence “turn-on” method for OTC detection was realized. Under the optimum conditions, the linear range of aptasensor was 0.05-50 μM, and the detection limit was 0.041 μM. In addition, the aptasensing method can be successfully used for the quantitative detection of OTC in milk and honey samples with a recovery rate of 95.67%-104.10% and 95.33%-109.70%, implying excellent analytical performance and practical application prospect.

Valence-dependent immune responses of earthworm coelomocytes: Toxicity pathways and molecular mechanisms of As (III) and As (V)-induced immunotoxicity

Epidemiological studies in inorganic arsenic (iAs) exposure populations have offered convincing evidence that exposure to arsenite (As (III)) and arsenate (As (V)) are linked to immune dysfunction and immunosuppression. However, the valence-dependent immunotoxicity mechanism of iAs has not been explored. In this work, we conducted a thorough investigation and comparison of lysosome dysfunction in As (III) and As (V) induced earthworm typical immune cells coelomocytes, and the binding reaction between As (III)/As (V) and immunoprotein lysozyme (LZM). Results indicated As (III) and As (V) induced severe alterations in NR uptake and caused serious damage to lysosomal membrane, particularly As (III). As (III) (21.24 %) had a stronger inhibitory effect on LZM activity in coelomocytes than As (V) (67.40 %), which showed a similar toxic trend as enzyme activity in vitro (As (III)-68.66 % and As (V)-78.50 %). LZM skeleton relaxation, secondary structural transformation, fluorescence sensitization and particle alteration provided evidence for As (III) trigger more grievous immunoprotein dysfunction. In conclusion, As (III) and As (V) triggered lysosomal membrane destruction in coelomocytes, as well as induced structural changes in LZM result in lysosomal hydrolase dysfunction in coelomocytes. Ultimately, cellular lysosome dysfunction and destruction, which leads to the normal immune system of the cells is disrupted. As (III) induced stronger immunosuppression through lysosome pathway than As (V). Our work reveals the degree of lysosome dysfunction triggered by As (III) and As (V) probably responsible for the valence-dependent immunosuppression patterns of iAs, and provide new insights for As toxicity assessment.

A simplified ratiometric fluorescent sensing strategy for enhanced detection of alkaline phosphatase employing Prussian blue nanozymes and commercially available chromogen

The traditional nanozymes-based ratiometric fluorescence sensing platforms usually necessitate the supplementary addition of fluorescent probes, therefore greatly restricting its convenient and broad application. In this study, a highly sensitive and selective ratiometric fluorescence platform for alkaline phosphatase (ALP) detection was established, only employing Prussian blue (PB) nanozymes and a commercially available chromogen of o-phenylenediamine (OPD). PB nanozymes with remarkable peroxidase-like (POD-like) activity can effectively catalyze OPD chromogen to yield 2,3-diaminophenazine (OPDox) with an intense yellow fluorescence at 573 nm emission peak. Target ALP can facilitate ascorbic acid 2-phosphate (AAP) dephosphorylation to generate phosphate and ascorbic acid (AA). Significantly, both these two resultant hydrolysis products could effectively decrease the OPDox generation via a dual-path based inhibition on the PB nanozymes POD-like activity. On the other hand, the generated dehydroascorbic acid (DHAA) from AA oxidation would exclusively react with OPD chromogen to yield 3-(dihydroxyethyl)furo[3,4-b]quinoxaline-1-one (DFQ) with a strong blue fluorescent signal at 434 nm, which further providing a significant enhancement on the sensing selectivity of ALP detection. As a result, an increased yellow fluorescence of OPDox and decreased blue fluorescence of DFQ could be clearly observed with different ALP addition. A robust linear relationship between the fluorescence ratio of F434/F573 and ALP activity ranging from 0.25 U/L to 6 U/L was obtained, with a low detection limit of 0.112 U/L. This proposed method demonstrates high sensitivity, excellent selectivity, cost-effectiveness, and operational simplicity, yet enabling an effective detection of ALP levels in human serum.

A hydrogel film microarray stabilizes very short structure switching aptamer duplexes to achieve enhanced sensing of small molecules

The reduction of affinity associated with the modifications required to create FRET- aptamer constructs represents a key challenge hindering the practical adaptation of such systems for small molecule detection. While the use of shorter and rationally positioned quencher stems is desirable to enhance target-induced fluorescence recovery, the weak hybridization potential of such stems results in high levels of background fluorescence and poor sensitivity. Herein, we introduce a hydrogel microarray sensor able to thermally stabilize very short aptamer duplexes (i.e., quencher stems ≤10-bp), resulting in improved FRET efficiency and reduced background levels across a broad range of conditions. The optimal hydrogel microarray can physically entrap >75 % of loaded aptamer reporters while maintaining high accessibility to the target molecules, enabling accurate quantification of dose-responsive affinity interactions. Using an ATP aptamer reporter, the hydrogel sensor can achieve a binding affinity as low as 14.7 µm − comparable to the native aptamer – and very low limits of detection (LOD) of 1.2 µm in a pure buffer and 4.6 µm in 50 % serum. Moreover, the developed hydrogel microarray is reusable, amenable to printing fabrication, and provides protection against nuclease-based degradation. This simple approach thus holds promise for advancing microarray aptamer technology in critical biosensing applications.

AIE Active Polymeric Fluorescent Nanoaggregates from Glycogen for Sensitive Detection of Tetracycline.

Detection and monitoring of environmental contaminants such as antibiotic residues in aquatic environments is challenging. To address this, a variety of detection methods has been developed; out of which optical sensing using fluorescence is found as one of the most robust methods. However, most of the reported sensors are made from metal ions using tedious synthetic processes, on the other hand, optical sensors using biosourced polymers are rarely reported. Herein, an anionic glycogen functionalized aggregation induced emission (AIE) active system; NCMCTPN was prepared using a simple Schiff base condensation reaction of tetraphenylethene amine (TPENH2) and carboxymethyl cellulose dialdehyde (NCMCA) and its self-assembled polymeric nanoaggregates were explored for sensitive and selective turn-off fluorescence detection of a broad-spectrum tetracycline antibiotic, in an aqueous medium with a limit of detection of 127.5 ppb. The combination of factors such as inner filter effect and photoinduced electron transfer from the polymeric nanoaggregates to tetracycline through activation of a non-radiative decay process is possibly responsible for the high sensitivity of the fluorescent nanoprobe towards the antibiotic.

Synthesis and utilization of luminescent hybrid films incorporating Y-CQDs for mercury ion detection

In this study, a highly selective and sensitive composite fluorescence sensor (Y-CODs @PVDF@PVP) was developed for the quantitative and visual detection of Hg2+ by electrostatic spinning carbon quantum dots (CQDs) with polyvinylidene fluoride (PVDF) and polyethylene pyrrolidone (PVP). The Y-CODs @PVDF@PVP composite fluorescence sensor exhibited strong yellow fluorescence under ultraviolet light (365 nm), demonstrating stable detection capability for mercury (II) in water samples. The morphology, chemical composition, and optical properties of Y-CODs @PVDF@PVP were thoroughly investigated. Different quenching effects were observed in Y-CODs @PVDF@PVP based on varying concentrations of Hg2+, enabling accurate determination of Hg2+. The achieved detection limit was 9.27 nM. Both static quenching and dynamic quenching mechanisms contributed to the observed results. Notably, the method successfully detected Hg2+ in real water samples from Beichuan Lake as well as rice samples, yielding satisfactory outcomes. Furthermore, when combined with software image analysis, quantitative and visual detection of field Hg2+ levels was accomplished using the composite fluorescence sensor. This research provides valuable insights for developing portable sensors aimed at monitoring harmful substances in water.

Peroxynitrite-Responsive Near-Infrared Fluorescent Imaging Guided Synergistic Chemo-Photodynamic Therapy via Biomimetic Metal-Organic Frameworks.

Peroxynitrite (ONOO-) plays a crucial role in maintaining cellular redox homeostasis and regulating diffusive processes, cellular transport, and signal transduction. Extensive studies have revealed that increased ONOO- levels during tumor progression are associated with heightened levels of oxidative stress. However, current methods lack noninvasive visualization, immediate reporting, and highly sensitive fluorescence sensing. In light of this, we have designed a biomimetic fluorescent nanoplatform, named Z-C-T@CM, for peroxynitrite-responsive near-infrared fluorescent imaging guided cancer treatment. The nanoplatform comprises tetrakis(4-carboxyphenyl) porphyrin (TCPP) and curcumin (CCM) encapsulated within a zeolitic imidazolate framework-8 (ZIF-8), which is coated with a mouse breast cancer cell membrane for enhanced biocompatibility and targeting, while evading immune clearance. In vitro experimental results demonstrate that the as-prepared nanoplatform exhibits enhanced near-infrared fluorescence emission upon exposure to ONOO-, indicating a significant potential for noninvasive in vivo imaging of ONOO- during tumor progression. Additionally, Z-C-T@CM readily degrades in the tumor microenvironment, releasing TCPP and CCM, enabling a synergistic chemo-photodynamic therapy with near-infrared illumination. Further investigations indicate that Z-C-T@CM efficiently stimulates a tumor immune response and facilitates therapeutic efficiency. Collectively, this work introduces a novel noninvasive strategy for ONOO- detection, shedding new light on the integration of cancer diagnosis and efficient treatment.

DFT supported studies of multi-responsive AIE active fluorophores for the sensitive fluorescence recognition of p-nitrophenol and pH: Vapor phase and solution mode sensing

Designing of an aggregation-induced emission (AIE) active multi-responsive fluorophores for the sensitive recognition of targeted analytes has been a hot spot in recent time. In pursuit of this endeavor, two chromene core sensors KG01 and KG02, installed with phenyl rotors, were efficiently designed, synthesized, and characterized through NMR spectroscopy. Proposed fluorophores demonstrated striking features of structure–property relationships, including solvatochromism and J-aggregates-based aggregation induced emission (AIE). Subsequently, well-thought-out developed sensors KG01 and KG02 were subjected to photoinduced electron transfer (PET) operated fluorescence quenching driven optical tracing of p-nitrophenol (p-NP) in the co-existence of competing analytes, with LOD down to 4.7 and 6.6 nM, respectively. Further, diversified theoretical calculations were executed to validate J-aggregates, supreme selectivity of sensors towards p-NP and PET as its primary sensing mechanism. Additionally, Jobs plot experiment, dynamic light scattering (DLS) size distribution, and 1H NMR titration assay also endorsed the selective p-NP sensing. Further, reported sensors were exploited for the fluorescence along with visual recognition of trifluoroacetic acid (TFA) and sodium hydroxide (NaOH). Interestingly, devised sensor KG01 disclosed naked-eye detection of TFA vapors. Furthermore, real water sample analysis, engineering of hand-held thin layer chromatography (TLC) plates-based fluorescent kits, and fabrication of logic devices were carried out to signify the convenient point-of-need applications of the proposed sensors. To the best of our knowledge, sensors KG01 and KG02 are first-ever solvatochromic and AIEgen chromenes with good quantum yield (Φ) and absorption coefficient as potential candidates to establish a range of easy-to-apply platforms for the selective and sensitive distinguishing of different aforementioned analytes. Given the role of p-NP as a priority pollutant from industrial sources with severe ecological and health impacts, these fluorescence sensors offer promising potential for developing cost-effective tools for rapid and precise trace-level detection. Additionally, industrial seepage of TFA and NaOH into water reserves poses serious health risks. These fluorescence sensors could be adapted to create devices capable of detecting these contaminants at nanomolar concentrations.

A Copper-Incorporated meso-(N'-acetyl-hydrizide)-BODIPY as a "Off-On" Fluorescent Probe for Histidine.

We present a highly sensitive and selective fluorescence "turn-on" sensor for l-histidine (His) detection in aqueous solutions utilizing a 1-Cu2+ complex. This sensing platform employs a fluorescence-based ligand displacement approach, featuring a meso-(N'-acetyl-hydrizide)-based BODIPY derivative (1) complexed with Cu2+. Initially highly fluorescent, compound 1 is selectively quenched by Cu2+ ions, forming the 1-Cu2+ complex. The high affinity between His and Cu2+ effectively displaces 1 from the complex, restoring fluorescence. The system exhibits rapid response (within 5 minutes), excellent sensitivity (detection limit of 78 nM), operational simplicity, and a large fluorescence "turn-on" signal. It demonstrates remarkable selectivity for His over other amino acids, with maleimide masking cysteine interference. Notably stable in complex biological matrices, the sensor has successfully quantified His in artificial urine samples. Its practical applicability extends to paper-based test strips, offering portability and potential for real-time His monitoring in clinical diagnostics and biological systems.

Optical immunosensor panel using quantum dot-antibody conjugates for highly sensitive detection of carbohydrate antigen 19–9 (CA19-9)

This study introduces a fluorescent immunosensor colour panel with antibody-conjugated quantum dots for detecting CA19-9 in human serum. The immunosensors presented decreasing fluorescence with increasing CA19-9 concentrations, with a linear detection range from 0.01 to 501.87 U mL−1 and detection limits of 1.66 × 10⁻⁴, 2.71 × 10⁻⁴, and 5.45 × 10⁻⁴ U mL−1 for the green-, orange-, and red-emitting conjugates in human serum. These limits are well below the 37 U mL−1 cutoff for early pancreatic cancer risk. The immunosensor panel is simple, sensitive, and specific, offering a visual colour readout for rapid CA19-9 detection, making it ideal for point-of-care applications. The results highlight the potential of the developed conjugates as a sensitive fluorescence colour panel for detecting CA19-9 across a wide range in human serum, both below and above the pancreatic cancer cutoff. With just 200 μL of sample and a single pre-filtration step, the assay delivers results in under 15 min, offering a cost-effective and efficient platform for point-of-care use.

Establishment of a high-sensitivity time-resolved fluorescence immunoassay with PLA2R-IgG1 antibody and its clinical application in idiopathic membranous nephropathy prognosis

IntroductionThe objective of this study was to develop a highly sensitive time-resolved fluorescence immunoassay (TRFIA) method to detect phospholipase A2 receptor (PLA2R)-IgG1 antibodies and evaluate its clinical relevance in predicting the prognosis of individuals with idiopathic membranous nephropathy (IMN). Materials and methodsA three-step indirect TRFIA method was established using a PLA2R antigen-coated microtiter plate to capture PLA2R-IgG antibodies, followed by detection using mouse anti-human IgG1 and Eu3+-labeled goat anti-mouse IgG antibodies. This method was applied to the initial serum of 56 patients with PLA2R-IMN to investigate the clinical value of PLA2R-IgG1 antibody levels in predicting IMN prognosis. ResultsThe detection range of PLA2R-IgG1-TRFIA was 0.85–300RU/mL, with intra-assay precision of 3.54–5.93 % and inter-assay precision of 4.39–9.36 %. Recoveries were 101.77–108.04 %. A PLA2R-IgG1 level above 2.21RU/mL indicated PLA2R-IMN. At initial diagnosis, the median PLA2R-IgG level was 51.24RU/mL in the remission group and 93.27RU/mL in the non-remission group. The median PLA2R-IgG1 level was 603.32RU/mL in the non-remission group, which was 4.29 times higher than that in the remission group (140.67RU/mL). PLA2R-IgG1 levels (P = 0.001) more effectively distinguished between remission and non-remission groups compared with PLA2R-IgG levels (P = 0.094). ConclusionsThe first quantitative TRFIA for PLA2R-IgG1 was established, showing greater clinical value in predicting IMN prognosis, compared to that for PLA2R-IgG levels.

In Situ Study on Biodegradation Differences Between Dissolved Phenanthrene and Methylphenanthrene Using First Derivative Synchronous Fluorescence Spectrometry With Double Scans.

A rapid and highly sensitive first derivative synchronous fluorescence spectrometry with double scans was successfully optimized for the simultaneous determination of dissolved phenanthrene (Phe), 1-methylphenanthrene (1-MP), and 3-methylphenanthrene (3-MP) and their metabolites such as 1-hydroxy-2-naphthoic acid (1H2NA) and salicylic acid (SA) in the biodegradation processes of Phe, 1-MP, and 3-MP by Novosphingobium pentaromativorans US6-1. Δλ of 55 and 109 nm were selected for Phe, 1-MP, 3-MP, 1H2NA, and SA, respectively. The intensities of the first derivative synchronous fluorescence detected at λex of 289, 292, 291, 354, and 312 nm for Phe, 1-MP, 3-MP, 1H2NA, and SA varied linearly with the concentrations of them in the ranges of 0.20 × 10-7-44.89 × 10-7, 0.20 × 10-7-13.04 × 10-7, 0.20 × 10-7-13.04 × 10-7, 0.22 × 10-7-76.30 × 10-7, and 0.11 × 10-7-52.00 × 10-7 mol/L. The limits of detection were 0.11 × 10-9, 0.30 × 10-9, 0.27 × 10-9, 0.33 × 10-9, and 2.90 × 10-9 mol/L for Phe, 1-MP, 3-MP, 1H2NA, and SA, respectively, with RSD less than 2%. The method was successfully applied in situ to detect the instantaneous concentrations of the PAHs and their metabolites, especially SA, during their biodegradation processes under simulated conditions in the lab. The results demonstrated that the upper metabolic pathways of 1-MP and 3-MP by US6-1 were distinctly different from that of Phe owing to steric hindrance of the methyl group.

Cr3+-Activated Deep Trap Electron-Trapping Biphasic Mixture of Zn (Al,Ga)2O4 and Zn2GeO4 for Multilevel Information Storage by Trap Multiplexing and Wavelength Multiplexing.

Double wavelength emitting phosphors with hypersensitive thermal response are important for optical/thermal sensors and multiplexing optical data storage technology. However, it is a daunting challenge to develop multicolor electron-trapping materials with superheat sensitivity and anomalous quenching luminescence characteristics for information storage. Here, based on the selection of host lattice and the control of doping ion types, we have designed Mn2+- and/or Cr3+-activated persistent materials with excellent fluorescence properties. Among these phosphors, Mn,Cr co-activated biphasic mixture exhibits not only sensitive anomalous thermosensitive fluorescence properties but also multicolor and multimode fluorescence emission characteristics derived from Mn and Cr simultaneously. The corresponding multimode fluorescence mechanism is proposed based on afterglow energy transfer and deepening trap effect. Especially, based on the excellent fluorescence performances, these phosphors as information storage medium demonstrate multilevel information storage by a combination of the trap multiplexing and wavelength multiplexing technologies. The study here provides not only the ideas for designing and synthesizing new electronic materials but also a material foundation for the fourth generation of optical information storage and encryption.

A highly sensitive fluorescence biosensor based on polylysine functionalized quantum dots for serum GDF-15 detection

A highly sensitive fluorescence biosensor based on polylysine functionalized quantum dots for serum GDF-15 detection

Thermally Activated Delayed Fluorescence Sensitizer with Through‐Space Charge Transfer Manipulated by Atom Distribution for Solution‐Processed Deep‐Blue Multi‐Resonance OLEDs

AbstractOrganic light‐emitting diodes (OLEDs) employing multi‐resonance (MR) emitters have attracted much attention due to their high luminescent efficiency and color purity, however, the development of deep‐blue multi‐resonance OLEDs is hindered by the lack of suitable sensitizers. Here a novel design strategy is reported for thermally activated delayed fluorescence sensitizer with high reverse intersystem crossing (kRISC) and radiative transition (kR) rate by regulating atom distribution of a spatially‐aligned carbazole donor/diphenylpyrimidine acceptor structure to manipulate through‐space charge transfer (CT) process. It is found that diphenylpyrimidine acceptor with 1,3‐position nitrogen atoms is un‐conjugated to bridging phenyl moiety by the conjugation node of pyrimidine, while the acceptor with 1,5‐position nitrogen atoms is conjugated to bridging phenyl through conjugation site, opening through‐bond CT pathway via bridging phenyl besides through‐space CT from spatial donor‐acceptor interactions. As a result, the sensitizer with 1,5‐position nitrogen atoms exhibits enhanced oscillator strength by 3.5 folds and accelerated kR of 3.57 × 107 s−1, while keeping high kRISC of 4.03 × 106 s−1 and high singlet (S1) state (2.88 eV). Solution‐processed OLEDs using the sensitizer and deep‐blue multi‐resonance emitter exhibit efficient narrowband electroluminescence with CIE coordinates of (0.14, 0.13) and EQEmax of 15.6%, representing the state‐of‐the‐art device performance for deep‐blue multi‐resonance OLEDs by solution process.

Responsive integration performed by laser-induced Er3+ structural doping and graphene nanoplatelets

Laser-induced preparation method has the advantages of high efficiency, high yield, no ionic diffusion restriction and competitive side reaction, which can prepare diversified composite materials based on small-scale and distributed characteristics. Besides, integrating multiple performance and conducting inductive feedback are helpful for the reliability and calibration of laser-induced materials in the precision field. Herein, responsive integration is designed based on graphene nanoplatelets/ZnSe:Er3+ composite with optical, electrical, thermal and visual properties for real-time feedback. Er3+ ions doped ZnSe is obtained by fast laser-induced method, combined with two-dimensional graphene nanoplatelets and assembled into temperature-sensitive polyimide and cellulose paper, realizing the characteristics of photoelectric conversion and photothermal conversion. Besides, red fluorescence guiding perceptual behavior can also be produced under the radiation of NIR laser. Based on the proposed composite, bionic flower is constructed, and exhibits good motion features in blooming. Meanwhile, large curvature bending, high thermal sensitivity and strong fluorescence emission are also revealed. Such performance combination design provides a convenient approach for multi signals cross feedback in soft actuator, which strengthens the monitoring and guidance of motion perceptions, and can be potentially applied in diversified fields.

Boronic Acid-Based Glucose Detection for Liver Three-Dimensional Cellular Models.

Liver 3D cell models are regularly employed as a screening platform for predicting the metabolic safety of drugs, by monitoring the physiological responses of the spheroids, through the measurement of relevant markers of normal liver physiology, notably glucose. Measuring glucose levels within the spheroids and their surroundings provides insight into the metabolic homeostasis of liver cells and may be employed as an indication of potential drug-induced toxicity. Several ortho-aminomethyl phenylboronic acid (PDBA) glucose sensors have been developed. Most recently, Mc-CDBA ((((((2-(methoxycarbonyl)anthracene-9,10-diyl)bis(methylene)) bis(methylazanediyl))bis(methylene))bis(4-cyano-2,1-phenylene))diboronic acid) was reported. Although Mc-CDBA exhibits good water solubility and sensitivity toward glucose, its ability for intra- and extracellular glucose monitoring in spheroids has not been determined. Here, we present a set of Mc-CDBA derivatives: carboxylic (BA) and amide (BA 5)-based Mc-CDBA sensors for extra- and intracellular glucose monitoring, respectively. Both sensors exhibit superior spectroscopic features. BA 5 showed selective intracellular accumulation in liver spheroids and exhibited more than 3-fold higher basal fluorescence sensitivity compared to Mc-CDBA. These observations led to the development of an extracellular hydrogel-embedded sensor (HG-BA 21) to monitor extracellular glucose levels under persistent solution flow mimicking physiological conditions. We have therefore demonstrated that the sensors developed by our team are suitable for a variety of assays, notably with liver spheroids, and provide powerful new tools for organ-on-a-chip applications predicting drug-induced liver injury in the early stages of drug development.

Dual-lock-and-key virus-mimicking nanoprobes for ultra-high accurate and sensitive imaging of viral infections in vivo

Fluorescence in situ imaging of viral infection lesions in vivo is crucial for precise diagnosis of viral diseases and evaluation of the extent of viral infection. Nevertheless, achieving highly specific and sensitive fluorescence imaging of viral infection sites in vivo has posed a persistent challenge. Here, we developed a dual-lock-and-key virus-mimicking nanoprobe that consisted of polyamide dendrimers (PAMAM) loaded internally with molecular beacons double-triggered by apurinic/apyrimidinic nucleic acid endonuclease 1 (APE1) and viral RNA (vRNA), and surface-modified with the E protein of Japanese encephalitis virus (JEV). This activatable nanoprobe generated dramatically amplified fluorescent signals stimulated by expressed vRNA and APE1 during viral infection, enabling ultrahigh specific and sensitive imaging of the lesions of JEV infection in vivo. This study provides a potential approach for accurate and sensitive detection of viral infection levels and assessment of the efficacy of antiviral drugs in vivo.

Photochemical and electrochemical behavior of a molecular probe: Fluorescence on-off-on response to detect multiple ions (Cu2+, ClO− and CN−) with different rate of reaction

A molecular probe 3 containing phenyl substituted imidazolyl unit and diaminomaleonitrile (DAMN) moiety has been synthesized and characterized. Photophysical and electrochemical behavior probe 3 were studied in partial aqueous medium (ACN/H2O, 9.5:0.5 v/v). Probe 3 upon interaction with different class of ions showed sensitivity for Cu2+, ClO− and CN− ions with different response time and reaction rates due to variation in intramolecular charge transfer (ICT) process. Both Cu2+ and ClO− ions displayed enhanced emission due to hydrolysis of imine bond to form compound 2 in the medium whereas, with CN− fluorescence quenching was observed due to the deprotonation of –OH/–NH2 functions. The kinetic and optical behavior of the probe suggested that interaction occurred in two steps with Cu2+ (complexation and hydrolysis; absk1,2,3(Cu2+) = 1.17, 0.74 and 0.06 s−1) and ClO− (hydrolysis and deprotonation; absk1,2(ClO−) = 3.0 and 0.60 s−1) ions while CN− (absk1,2(CN−) = 2.13 and 1.66 s−1) induces deprotonation in one step. The interaction of probe 3 with ClO− was relatively fast than with Cu2+/CN− ions. Job's plot analysis between probe 3 and ions revealed a 1:1 (Cu2+/ClO−) and 1:2 (CN−) ratio stoichiometry with good limit of detection (nM) and binding affinity (LOD, 17; KCu2+ = 3.23 × 106 M−1; LOD, 18.5; KClO− = 5.23 × 105 M−1 and LOD, 23.2; KCN− = 5.50 × 109 M−2) respectively. Probe 3 displayed a naked–eye sensitive fluorescence response to detect tested ions on test paper strips and good recovery percentage of ions in real water sample analysis.