Cross-Linking Induced Emission of Polymer Micelles for High-Contrast Visualization Level 3 Details of Latent Fingerprints

Photo-responsive color/fluorescence efficient dual-switching properties of diarylethene modified Eu-doped ZnO@Silane quantum dots

Photo-responsive switches are very promising materials due to their potential applications in many fields. However, photo-controlled color/fluorescence dual-switching with higher modulation efficiency has rarely been reported. Herein, two new optical responsive switches were constructed by Eu-doped ZnO@Silane quantum dots (Eu:ZnO@Silane QDs) and two diarylethenes. The two switches exhibited strong fluorescence intensity and excellent photochromic properties due to the doping of Eu and the diarylethene modification on the surface of the QDs. The switches showed outstanding photo-controlled color/fluorescence dual-switching performance with UV/Vis lights irradiation. Although the structure of the two diarylethenes affected the fatigue resistance of the two switches, their fluorescence modulation efficiency (FME) could reach 100%. Furthermore, the two switches were successfully applied to bioimaging, and provide an alternative way for the design and construction of novel efficient color/fluorescence dual-switching.

Aminopeptidase N-Triggered Electron Rearrangement of Fluorescein for Covalent Fluorescent Labeling and Image-Guided Orthotopic Bladder Cancer Resection

Bladder cancer is the most common type of malignant tumor in the urinary system, which occurs in the bladder mucosa. Due to the lack of precise diagnostic tools, bladder cancer has a high recurrence rate. Fluorescence cystoscopy is recognized as a promising tool for improving the detection rate of bladder cancer, but its clinical application is hindered due to the scarcity of fluorescent agents. To address this issue, an aminopeptidase N (APN)-activated fluorescent agent with specific recognition and labeling abilities for bladder cancer has been developed. The fluorescent agent, namely, Flu-FAPN, exhibited high sensitivity and specificity toward APN under physiological conditions. The fluorescent intensity increased more than 37-fold after reacting with APN, and the detection limit is 0.10 ng/mL for APN. In addition, the hydrolysis of alanine catalyzed by APN could initiate the intramolecular electron rearrangement process, which subsequently contributed to the formation of protein-fluorescein adduct and thereby achieved covalent labeling of bladder cancer cells. Cell experiments conducted in cancer and normal cells demonstrate that Flu-FAPN has low cytotoxicity and high specificity for bladder cancer cells with an obvious fluorescence signal, which could be retained over 80% even in fixed cells. Finally, Flu-FAPN was successfully applied for the fluorescence-image-guided resection of tumor tissues in mice with orthotopic bladder cancer. We hope this covalent labeling-based agent can provide a promising tool for surgery navigation and accelerate the clinical application of fluorescence cystoscopy, thereby improving the cure rate of bladder cancer.

Emerging fluorescent probes for bioimaging of drug-induced liver injury biomarkers: Recent advances

Drug-induced liver injury (DILI) has emerged as a significant concern in clinical settings, being one of the leading causes of acute liver failure. However, the specific pathogenesis of DILI remains unclear, and there is currently a lack of effective targeted therapies. Numerous studies have demonstrated that the occurrence and progression of DILI involve complex pathological processes, closely linked with various cellular substrates and microenvironments. Thus, developing non-invasive, highly sensitive, specific, and reliable methods to detect changes in biomarkers and microenvironments in situ would greatly aid in the precise diagnosis of DILI and help guide therapeutic interventions. Fortunately, fluorescence imaging technology has shown great promise in detecting biological species, microenvironments, and diagnosing DILI due to its superior detection capabilities. In this context, this review described the design strategies, working principles, and practical applications of small molecule fluorescent probes for monitoring biological species and microenvironments in DILI. Importantly, this review highlighted current limitations and future development directions, which may help uncover the underlying relationships between biological species, microenvironments, and DILI. This understanding could lead to potential diagnostic protocols and establish a platform for evaluating treatments and drug efficacy in DILI.

Dye-sensitized lanthanide-doped upconversion nanoprobes for homocysteine sensing in human serum and living cells via a spatial optimization strategy

Homocysteine (Hcy) is an established risk factor for cardiovascular and neurodegenerative diseases, making its real-time detection critical for maintaining physiological balance and monitoring disease progression. However, developing probes that specifically recognize Hcy with a high signal-to-background ratio remains a significant challenge. In this study, we present a novel upconversion nanoprobe for Hcy detection, which integrates NIR cyanine dyes (CyPd) with β-NaGdF4:Yb20%,Er2%@NaGdF4:Yb10%,Nd10% upconversion nanoparticles (UNs). CyPd, featuring α,β-unsaturated ketone and pyridine functional groups, serves as both an efficient energy donor and a recognition antenna for the UNs. Benefiting from a hydrogen bonding-assisted two-site strategy of CyPd, coupled with highly efficient energy transfer from CyPd to UNs, the nanoprobe demonstrates high selectivity and sensitivity for Hcy in aqueous solutions, achieving a low detection limit of 0.19 μM. Importantly, the nanoprobe exhibits excellent performance in human serum, with recovery rates ranging from 97.9% to 103.2% and a low relative standard deviation of less than 3.51%. Furthermore, it was successfully applied for both exogenous and endogenous Hcy bioimaging. This innovative nanoprobe offers a promising tool for the accurate and efficient detection of Hcy, with potential applications in disease diagnosis and monitoring.

Mapping human fingerprint beyond level-3 based on an amphiphilic aggregation-induced emission luminogen and the construction of intelligent platform for personal identification

BACKGROUND

Fluorescence imaging agents have been benefiting tremendously from tailor-made aggregation-induced emission (AIE) luminogens, owing to their high on-off ratio, large signal contrast, low background noise as well as the resistance to photobleaching. In the domain of fingerprint imaging, AIE luminogens are beginning to exhibit an advantage owing to the aforementioned superiorities.

RESULTS

We present an amphiphilic benzoic-acid salicylaldehyde AIE luminogen AIE-BASB, and outline its water sensitivity, self-assembly behavior as well as fingerprint imaging properties. AIE-BASB self-assembles into nanoscale textures when fabricated into a drop-casting film but undergoes a disassembly process in response to trace water on fingertip upon physical-contacting. Owing to the biological textures on the skin, fingerprint image can be clearly recorded by AIE-BASB film, which reveals detailed microscopic features of fingerprint information ranging from level-1 to level-3. Furthermore, it allows accurate measurements of the sizes, shapes, centroids, and areas of the sweat pores, which leads the fingerprint information into the next level. In addition, we develop an intelligent system based on AIE-BASB by integrating hardware and software modules, which is capable of recording and identifying fingerprint. After inputting fingerprint segments in trial operation, this intelligent system makes identification by calculation of the categorical probability, and successfully predicts the classification of the undefined fingerprint segments, implying 100 % accuracy in fingerprint identification.

SIGNIFICANCE

We predict that AIE-BASB may facilitate the development of new biometric technologies, which have broad applications in the domain of artificial intelligence, including machine tactility, target perception and object-machine interaction.

A BODIPY-based fluorescent probe for rapid detection of NO in cells and zebrafish

Nitric oxide (NO) is a small biological molecule that plays a critical role in numerous physiopathological processes throughout the human body. An extensive array of studies has elucidated a robust correlation between pathological conditions and endogenous levels of NO. In this paper, we synthesized a BODIPY-based fluorescent probe, dubbed BDD, which has excellent ability to accurately detect NO. The presence of secondary amines of BDD enables it to engage in an N-nitrosation reaction with NO. This chemical interaction effectively disrupts the initial photoinduced electron transfer (PET) process, thereby facilitating the transition of BDD from a "turn-off" to a "turn-on" state. Moreover, BDD boasts several significant advantages including an expedient detection time (60 s), exceptional selectivity, and formidable anti-interference capabilities-factors that are indispensable for accurately detecting NO amidst complex environments. Furthermore, BDD demonstrates efficacy in discerning both endogenous and exogenous sources of NO within live cells and has been adeptly employed for imaging external substances in zebrafish.

An "On-Off" AIE-Based Lock-and-Key Fluorescent Probe System for Detection of Fentanyl/Norfentanyl

The misuse of fentanyl poses significant social risks, and accurately and swiftly detecting fentanyl in field settings presents a considerable challenge. Herein, we have designed and synthesized a fluorescent probe TP-CF3-COOH, which is composed of carboxyl- and trifluoromethyl-binding center tetraphenyl butadiene. The unique centrosymmetric configuration of the TP-CF3-COOH probe allows for the construction of a fluorescence "on-off" mechanism recognition platform by spatially matching fentanyl and its metabolite norfentanyl. Importantly, this study reveals that the interaction of fentanyl or norfentanyl with TP-CF3-COOH results in spontaneous self-assembly, generating a three-dimensional complex sphere that is smaller than the two-dimensional sheet fluorescence probe. This self-assembly process results in the quenching of fluorescence. Theoretical calculations demonstrate that this process is accompanied by intermolecular through-space charge transfer during self-assembly, leading to a blue shift in emission wavelength. As a result, the TP-CF3-COOH fluorescent probe enables the quantitative detection of fentanyl/norfentanyl within a range of 1 × 10-2-1 × 103 μg/L, with limits of detection of 2 × 10-4 μg/L and 3 × 10-4 μg/L, respectively. This cost-effective, rapid, and sensitive fluorescent probe holds great potential for the onsite screening and detection of fentanyl and its analogues.

Detecting Changes in Singlet Oxygen and Viscosity during Apoptosis-Ferroptosis Mediated Photodynamic Therapy and Establishing Visual Imaging of Fatty Liver

Cancer is a serious global health threat, and photodynamic therapy (PDT) is an effective treatment method for cancer. This therapy works by generating a large amount of singlet oxygen (1O2) under the influence of oxygen and light, which induces apoptosis in tumor cells, leading to their destruction. However, the resistance of cells to apoptosis limits the development of PDT, and thus the combination of ferroptosis and apoptosis provides a new perspective for PDT. During PDT and ferroptosis, the levels of 1O2 and the microenvironment (viscosity) within cells often change. To address this, this study developed a novel fluorescent probe, NI-QM-OH, based on the TICT-ICT effect, capable of monitoring changes in 1O2 and viscosity during PDT. The probe exhibits excellent selectivity, high sensitivity, and a low LOD (0.38 μM), and has been successfully applied for bioimaging in HepG2, HeLa, and MCF-7 cells, as well as for monitoring viscosity and 1O2 levels in zebrafish. Most importantly, NI-QM-OH also enables the visualization of the diagnosis of fatty liver disease (both alcoholic and nonalcoholic).

Asymmetric D-A-D' Ratiometric Molecule for Highly Specific Hypochlorous Acid Detection

Hypochlorous acid exists as HClO in acidic conditions and as ClO- in alkaline conditions, posing a significant challenge for differentiation due to their strong and closely similar oxidative reaction activities. Addressing this challenge, our study presents an asymmetric donor-acceptor-donor' (D-A-D') molecular architecture for the design of a fluorescent probe (PMT NPs) that demonstrates exceptionally high specificity toward HClO alongside an optimized ratiometric response. The incorporation of the strong electron acceptor 2-(diphenylmethylene)malononitrile (A) modulates the reducing ability of the phenothiazine recognition site, adjusting the probe's oxidation potential to an intermediate level between HClO and ClO-. This adjustment directly dictates the probe's selectivity, enabling it to respond exclusively to HClO. By incorporating D', the probe's response to HClO shifts the intramolecular charge transfer (ICT) from the original D-A to D'-A, instead of the usual Dox-A as presented in previous works. This adjustment controls the blue shift in fluorescence wavelength upon recognition, thereby improving the accuracy of ratiometric signals in vivo. The ability of PMT NPs to precisely recognize HClO in acidic environments was validated through live cell imaging and in vivo experiments using zebrafish and mouse models, enabling real-time monitoring of HClO surges. This dual-pronged molecular design strategy, which combines D-A interaction modulation with a D-A-D' molecular architecture, promises to revolutionize probe designs for various biomolecules and is anticipated to advance the understanding of diseases linked to these analytes.

A highly-sensitive fluorescent probe for the detection of copper ions and its applications in water quality monitoring, neural cell imaging and plant imaging

High copper levels pose a risk to environmental and human health due to their toxicity and widespread industrial application, in which abnormal copper levels are associated with various diseases both in neurodegenerative diseases and plant growth. Thus, a turn-on fluorescent probe BBYD-Cu, based on donor-acceptor type structure, was designed and synthesized with easy preparations. BBYD-Cu can specifically recognized Cu2+ by 2-picolinic ester group, then released the fluorophore to enhance the fluorescent signals. With a detection limit of 31 nM, it displays extremely sensitive and precise Cu2+ detection. In addition, BBYD-Cu has the advantages of fast response speed (within 3 min), excellent selectivity and strong anti-interference ability for Cu2+. Significantly, the BBYD-Cu demonstrates superior detection and imaging performance even in intricate real-world environmental samples, biological nerve cells and plant soybean sprout root tissue.

Hypochlorous Acid-Activatable NIR Fluorescence/Photoacoustic Dual-Modal Probe with High Signal-to-Background Ratios for Imaging of Liver Injury and Plasma Diagnosis of Sepsis

Hypochlorous acid can be employed as a biomarker for blood infection (such as sepsis) and tissue damage (such as drug-induced liver injury, DILI), and the diagnosis of tissue damage or blood infection can be achieved through the detection of hypochlorous acid in relevant biological samples. Considering the complex environment and the diverse interferences in living organisms and blood plasma, developing new detection methods for HClO with high signal-to-background ratios is particularly important, and it can improve the accuracy of detection and quality of imaging based on a higher contrast, which makes the detection of HClO clearer and more accurate. Here, based on the advantages of the NIR fluorescence/photoacoustic dual-modal probe, we reported a hypochlorous acid-activatable NIR fluorescence/photoacoustic dual-modal probe (NIRF-PA-HClO) based on the spirolactam ring-opening strategy in this paper. NIRF-PA-HClO showed excellent NIRF/PA dual-modal responses with high SBRs for HClO in solution, cells, and mice. Moreover, NIRF-PA-HClO was successfully applied for high-contrast imaging of DILI. Finally, NIRF-PA-HClO was employed for the blood plasma diagnosis of sepsis with satisfactory results. In summary, the above results proved that NIRF-PA-HClO would be a potentially useful tool for the study of physiological and pathological roles of HClO, the investigation of the pathology and therapeutic mechanisms of hepatotoxicity, and the diagnosis of blood infection. Also, the development of NIRF-PA-HClO provides new design mentality for constructing other analyte-activatable NIRF/PA dual-modal probes with high SBRs.

Fluorescence tunable carbon dots for in vitro nuclear dynamics and gastrointestinal imaging in live zebrafish and their in vivo toxicity evaluation by cardio-craniofacial disfunction assessment

Sub-cellular organelle anomalies are frequently observed in diseases such as cancer. Early and precise diagnosis of these alterations can be crucial for patient outcomes. However, current diagnostic tools using conventional organic dyes or metal quantum dots face limitations, including poor biocompatibility, stringent storage conditions, limited solubility in aqueous media, and slow staining speeds. These challenges underscore the need for safer, more effective diagnostic and therapeutic solutions. In these aspects, we have developed highly photostable, biocompatible, water-dispersible carbon dots (TNCDs) with an average size of 5.5 nm using tartaric acid and ethylenediamine via a hydrothermal route. The synthesized TNCDs have shown bright blue fluorescence under the irradiation of UV-light at an excitation wavelength of 365 nm. They exhibit a quantum yield (QY) of 25.1% with maximum emission at 390 nm. A nice tri-exponential fitting of the decay curve with characteristic lifetimes of 1.52 ns, 3.05 ns and 6.11 ns for TNCDs was obtained. In vitro studies demonstrated that TNCDs have high biocompatibility (20 μg ml-1) with almost 100% cell viability and excellent nucleus targeting and staining capabilities with low background interference (with 10-12 times enhancement in fluorescence intensity). Additionally, if tagged with photosensitizers or radionuclides, TNCDs can serve as therapeutic agents in photodynamic therapy against cancer cells. Importantly, TNCDs exhibited negligible toxicity in developing zebrafish even at high concentrations (up to 400 mg L-1) as investigated by cardio and craniofacial disfunction assessment. Live organism imaging revealed that TNCDs produced aggregation-induced strong and specific green fluorescence in the gut of zebrafish larvae even at low concentrations, indicating their potential for nucleus staining and gut-specific optical imaging (at 50 mg L-1). Thus, our TNCDs represent a robust nanoplatform for cellular and whole-organism fluorescence imaging, offering both diagnostic and therapeutic potential.

Near-Infrared Fluorescent Probe for Simultaneously Imaging Ferrous Ions and Viscosity in a Mouse Model of Hepatocellular Carcinoma

Abnormal ferrous ion (Fe2+) levels lead to an increase in reactive oxygen species (ROS) in cells, disrupting intracellular viscosity and the occurrence of hepatocellular carcinoma (HCC). Simultaneously visualizing Fe2+ and intracellular viscosity is essential for understanding the detailed pathophysiological processes of HCC. Herein, we report the first dual-responsive probe, QM-FV, capable of simultaneously monitoring Fe2+ and viscosity. QM-FV shows highly selective turn-on near-infrared fluorescence (∼30-fold enhancement at 740 nm) for Fe2+ with high sensitivity (LOD = 25 nM) and a significant Stokes shift (290 nm). Moreover, QM-FV shows a distinct orange-red fluorescence enhancement at 587 nm as the viscosity increases. Due to its lower cytotoxicity and high sensitivity, QM-FV can distinguish cancer cells from normal cells by detecting Fe2+ and viscosity in dual channels. More importantly, using QM-FV, we found that the levels of Fe2+ and viscosity elevated in the precancerous stage of HCC and gradually increased as the disease progressed. Overall, this work provides a new potential tool for investigating viscosity and Fe2+-related pathological processes underlying HCC.

Curcumin/kaolin composite for advanced latent fingerprint imaging with fluorescence quantification

Latent fingerprints (LFPs) are invisible impressions that need to be developed before being used for criminal investigation; however, existing fingerprint visualization techniques face challenges, such as complex preparation and poor contrast. To advance practical fingerprint detection, green-emissive micron-sized curcumin/kaolin composites were synthesized via a facile and cost-effective one-step physical cross-linking method, which exhibited unprecedented performance in developing diversified marks, including LFPs, knuckle prints, palm prints, and footprints, with clear three-level details on various substrates. Notably, the powders successfully developed LFPs that were aged for 30 days and even up to 100 days, meeting the stringent requirements for comprehensive forensic application. Afterward, a novel method, termed Fingerprint Fluorescence Intensity Ratio (FFIR), was developed to quantify the contrast between fingerprint signals and background noise and to compare the efficacy of full-color developing agents. Compared with the existing grayscale conversion strategy, the proposed FFIR method achieved tunable multi-color fingerprint image enhancement for the first time, which helped to eliminate background fluorescence interference and improved visual perception. The feasibility of FFIR and its sensitivity in tracking image capture parameters were demonstrated by the established mathematical model. Hence, the newly synthesized modified composites and the mathematical model-validated method demonstrate profound practical significance in comprehensive fingerprint imaging.

Diselenides as novel effective fluorescence quenchers to construct a two-photon fluorescent probe for thiols in a mouse stroke model

A fluorescence quenching mechanism using linear diselenides was proposed for the first time through a combination of intramolecular charge transfer (ICT) and Förster resonance energy transfer (FRET). Herein, we synthesized and screened a two-photon fluorescent probe AFC-SeSe, demonstrating a remarkable 300-fold increase in response to glutathione (GSH). Additionally, AFC-SeSe enabled real-time observation of increased thiol levels following treatment within a short timeframe in a mouse model of stroke.

Rotor proliferation promotes high-brightness AIE of iridium emitter accomplishing high-contrast luminous imaging of latent fingerprints to level 3 details

Luminous imaging of latent fingerprints (LFPs) necessitates the possession of high-brightness aggregation-state luminescence by developers to ensure sufficient imaging contrast and resolution. A novel strategy involving incremental rotor modification is presented for AIE activation of the iridium developer. The rotor proliferation prominently improves the rotational activity of groups and facilitates high-efficiency RIM, thereby prompting the AIE activation of iridium developer with high luminous efficiency. Subsequently, a prompt, high-contrast, and robust LFP imaging protocol is developed utilizing the high-brightness AIE-active iridium developer. This innovative protocol realizes the luminous imaging and quantification of microscopic features in fingerprint ridges and furrows, including ridge widths, edge morphology of ridges, included angles, pores, and pore pitches with exceptional imaging contrast and refined detail resolution. Moreover, it allows for accurate identification of individual traits across diverse substrates without any pre-/post-processing to LFPs. The high-brightness AIE-active iridium developer provides outstanding aging resistance to developed fingerprints, thereby strongly supporting the acquisition, transfer, and preservation of fingerprint evidence. The luminous imaging protocol of LFPs based on high-brightness AIE exhibits robust adaptability to actual scenes and offers a premium scheme for facilitating forensic investigation.

A near-infrared frequency upconversion fluorescent probe for rapid and sensitive visual detection of sulfur dioxide

Inflammation is a complex physiological response involving various cellular and molecular events. Sulfur dioxide (SO2), which is usually in the form of HSO3- and SO32- under physiological conditions, plays a crucial role in the regulation of inflammation and diseases. Frequency upconversion luminescence (FUCL) can realize the unique anti-Stokes process of long-wavelength excitation to short-wavelength emission; thus, it is a highly promising optical method for in vivo imaging due to its deep tissue penetration, low photo-damage, etc. Therefore, we developed a near-infrared FUCL NIRX-1 probe for the detection of HSO3-. NIRX-1 had a fast response (80 s), a low detection limit (0.43 μM), and high selectivity towards HSO3-. In addition, NIRX-1 had deep light penetration ability due to the near-infrared excitation at 808 nm and was able to detect HSO3- in living cells and mice. Lastly, NIRX-1 was employed in the imaging of HSO3- in an inflammation mouse model through FUCL imaging techniques. All these features make NIRX-1 a good candidate for the investigation of SO2-associated physiological and pathological processes.

Luminescent nanomaterials for developing high-contrast latent fingerprints

Fingerprint patterns (or epidermal ridges) are by far one of the most reliable techniques for individual identification. Fingerprint patterns get deposited on all kinds of solid surfaces due to human transudation or exudation process. Bodily fluids through sweat glands contain moisture, natural oils and proteins. Since latent fingerprint patterns are not readily recognizable they are collected from a crime scene and are further processed physically or chemically. Fingerprints obtained using conventional black and white powders face severe drawbacks including low sensitivity, high background interference from the substrates, involvement of toxic materials, and poor stability. To overcome the above-listed issues, especially for coloured and transparent substrates, luminescent materials have emerged as potential agents for rapid visualization of high-contrast latent fingerprints. This review covers the recent advancements in luminescent nanomaterials of both kinds (up and down conversion) and persistent nanophosphors for developing latent fingerprints. Special emphasis has been given to an unusual class of luminescent materials known as persistent nanophosphors, which do not require a constant excitation, thereby completely eradicating background noise. The review also covers different approaches to gathering fingerprints such as powder dusting, cyanoacrylate fuming, ninhydrin fuming and vacuum metal deposition.

Simple cyclic chalcone dye with multiple optical functions: Piezochromism and lysosomes staining

Both artificially synthesized and naturally occurring cyclic chalcones have been widely studied for their excellent biological activities. However, research on its photophysical properties is still limited. In the present study, we designed and synthesized a small molecule fluorescent dye based on the ICT effect, using dimethylamino as the electron-donating group and carbonyl as the electron withdrawing group, and investigated its photophysical properties in depth. Although YB is a simple small molecule, it exhibits significant piezochromic properties. The fluorescence of YB can change from green to yellow through grinding. After solvent fumigation, the fluorescence reverts to green. Furthermore, YB was used successfully in the lysosomal targeting. This study expands the research on the photophysical properties of cyclic chalcone and give richness to application of cyclic chalcone compounds.

Theoretical Investigations on the Sensing Mechanism of Dicyanoisophorone Fluorescent Probe for the Detection of Hydrogen Sulfide

As one of the biomolecules, hydrogen sulfide (H2S) has received a lot of attention. Recent studies have shown that endogenous hydrogen sulfide plays different roles in different organs in biological systems. Fluorescent probe technology has been widely adopted due to its many advantages such as low cost, simple operation, and high sensitivity. Among many probes, dicyanoisophorone fluorophore is often used in probe design for real-time detection of endogenous H2S due to the large Stokes shift and long fluorescence emission wavelength. In this paper, the fluorescence sensing mechanism of dicyanoisophorone-like probe L and its product 3 with near-infrared fluorescence emission has been theoretically investigated by using theory methods. The analysis of infrared (IR) vibration spectra and reduced density gradient (RDG) showed that the hydrogen bond of the enolic structure of product 3 was significantly enhanced in the S1 state. The spectroscopic information revealed that the emission of NIR fluorescence originated from the keto structure of the product. Finally, potential energy curves and frontier molecular orbitals diagrams showed that the fluorescence quenching phenomenon of the probe L was attributed to the photoinduced electron transfer (PET) process, whereas the product 3 generated after the detection of H2S undergoes the excited state intramolecular proton transfer (ESIPT) process.

Phenylboronic Acid-Functionalized Ratiometric Surface-Enhanced Raman Scattering Nanoprobe for Selective Tracking of Hg2+ and CH3Hg+ in Aqueous Media and Living Cells

The development of appropriate molecular tools to monitor different mercury speciation, especially CH3Hg+, in living organisms is attractive because its persistent accumulation and toxicity are very harmful to human health. Herein, we develop a novel activity-based ratiometric SERS nanoprobe to selectively monitor Hg2+ and CH3Hg+ in aqueous media and in vivo. In this nanoprobe, a new bifunctional Raman probe bis-s-s'-[(s)-(4-(ethylcarbamoyl)phenyl)boronic acid] (b-(s)-EPBA) was synthesized and immobilized on the surface of gold nanoparticles via a Au-S bond, in which the phenylboronic acid group was employed as the recognition unit for Hg2+ and CH3Hg+ based on the Hg-promoted transmetalation reaction. In the presence of Hg2+ and CH3Hg+, a new surface-enhanced Raman scattering (SERS) peak aroused from of C-Hg appeared at 1080 cm-1, and the SERS intensity at 1002 cm-1 belonged to the B-O symmetric stretching decreased simultaneously. The quantitative tracking of Hg2+ and CH3Hg+ was realized based on the SERS intensity ratio (I1080/I1303) with rapid response (∼4 min) and high sensitivity, with detection limits of 10.05 and 25.13 nM, respectively. Moreover, the SERS sensor was used for the quantitative detection of Hg2+ and CH3Hg+ in four actual water samples with a high accuracy and excellent recovery. More importantly, cell imaging experiments showed that AuNPs@b-(s)-EPBA could quantitatively detect intracellular CH3Hg+ and had a good concentration dependence in ratiometric SERS imaging. Meanwhile, we demonstrated that AuNPs@b-(s)-EPBA could detect and image CH3Hg+ in zebrafish. We anticipate that AuNPs@b-(s)-EPBA could potentially be used to study the physiological functions related to CH3Hg+ in the future.

Aggregation-induced emission luminogens for latent fingerprint detection

For over a century, fingerprints have served as a pivotal tool for identification of individuals owing to their enduring characteristics and easily apparent features, particularly in the realm of criminal investigations. Latent fingerprints (LFPs) are "invisible fingerprints" that are most commonly available at crime scenes and require a rapid, selective, sensitive, and convenient method for detection. However, existing fingerprint development techniques harbour limitations, prompting the exploration of novel approaches that prioritize investigator safety and environmental sustainability. Leveraging the unique photophysical properties of aggregation-induced emission luminogens (AIEgens) has emerged as a promising strategy for on-site analysis of LFP visualization. In this highlight, we have presented a comparative analysis of various AIEgens (organic compounds, metal complexes, nanoparticles, and polymers) for the development and detection of LFPs. Through this examination, insights into the efficiency and potential applications of AIE-based fingerprint development techniques are provided. In addition, several strategies have been proposed for circumventing the limitations of existing AIEgens. We hope that this highlight article will encourage more researchers to investigate AIEgens in LFP detection, contributing to forensic science.

Molecule Engineering Metal-Organic Framework-Based Organic Photoelectrochemical Transistor Sensor for Ultrasensitive Bilirubin Detection

The functionalization of metal-organic frameworks (MOFs) with organic small molecules by in situ postsynthetic modification has garnered considerable attention. However, the precise engineering of recognition sites using this method remains rarely explored in optically controlled bioelectronics. Herein, employing the Schiff base reaction to embed the small molecule (THBA) into a Zr-MOF, we fabricated a hydroxyl-rich MOF on the surface of titanium dioxide nanorod arrays (U6H@TiO2 NRs) to develop light-sensitive gate electrodes with tailored recognition capabilities. The U6H@TiO2 NR gate electrodes were integrated into organic photoelectrochemical transistor (OPECT) sensing systems to tailor a sensitive device for bilirubin (I-Bil) detection. In the presence of I-Bil, coordination effects, hydrogen bonding, and π-π interactions facilitated strong binding between U6H@TiO2 NRs and the target I-Bil. The electron-donating property of I-Bil influenced the gate voltage, enabling precise control of the channel status and modulation of the channel current. The OPECT device exhibited exceptional analytical performance toward I-Bil with wide linearity ranging from 1 × 10-16 to 1 × 10-9 M and a low limit detection of 0.022 fM. Leveraging the versatility of small molecules for boosting the functionalization of materials, this work demonstrates the great potential of the small molecule family for OPECT bioanalysis and holds promise for the advancement of OPECT sensors.

Detection and application of hypochlorous acid in both aqueous environments and living organisms

The scarcity of water resources has raised concerns regarding drinking water safety. Excessive addition of hypochlorous acid (OCl-) as a disinfectant in drinking water can result in severe consequences. Moreover, abnormal levels of OCl- within the human body can lead to various diseases. Employing fluorescence analysis, the design and synthesis of specific fluorescent probes for simultaneous detection of OCl- in water environments and living organisms holds strategic significance in ensuring the safety of drinking water and mitigating potential risks caused by its abnormal concentrations. This article utilizes naphthalimide as a precursor to develop a novel probe enabling highly sensitive detection of OCl- in water environments and at the organelle level within living organisms. This endeavor serves to provide assurance for drinking water safety and offers health alerts.

Near-infrared dual-response fluorescent probe for detection of N2H4 and intracellular viscosity changes in biological samples and various water samples

N2H4 is a common raw material used in the production of pesticides and has good water solubility, so it may contaminate water sources and eventually enter living organisms, causing serious health problems. Viscosity is an important indicator of the cellular microenvironment and an early warning signal for many diseases. The high reactivity of hydrazine depletes glutathione (GSH) in hepatocytes, causing oxidative stress ultimately leading to significant changes in intracellular viscosity and even death. Therefore, it is particularly important to develop an effective method to detect N2H4 and viscosity in environmental and biological systems. On this basis, we developed two fluorescent probes, BDD and BHD, based on xanthene and 2-benzothiazole acetonitrile. The experimental results show that BHD and BDD have good imaging capabilities for N2H4 in cells, zebrafish and Arabidopsis. BHD and BDD also showed sensitive detection and fluorescence enhancement in the near-infrared region when the intracellular viscosity was changed. Notably, the probe BDD has also successfully imaged N2H4 in a variety of real water samples.

User-Friendly Multifunctional Red-Emissive Carbon Dots for Rapid Cell Nucleus Staining via Targeting Nuclear Proteins

Cytoarchitectural staining is of great importance in disease diagnosis and cell biology research. This study developed user-friendly multifunctional red-emissive carbon dots (R-CDs) for rapid cell nucleus staining via targeting nuclear proteins. R-CDs, simply prepared by electrochemical treatment of 1,2,4-benzenetriamine, exhibit strong emission at 635 nm when excited at 507 nm. The R-CDs can rapidly stain the nucleus of human SH-SY5Y, HepG2, and HUH-7 cells with a high signal-to-noise ratio owing to fluorescence enhancement after entering the nucleus. Compared to conventional cytosolic dyes such as Hoechst and DAPI, R-CDs are cheaper, more highly dispersed in water, and more stable (requiring no stringent storage conditions). The R-CDs show stable optical properties with insignificant photobleaching over 7 days and salt resistance up to 2 M of NaCl. More importantly, R-CDs, possessing a positive charge, allow rapid staining of live cells (3 min) and dead cells (10 s) in saline. According to kinetic variation, R-CDs can distinguish live cells from dead cells. Staining exhibits high efficiency in onion epidermal cells, Aspergillus niger, Caenorhabditis elegans, and human spermatozoa. The mechanism for efficient staining is based on their fast accumulation in the nucleus due to their small size and positive charge and strong interaction with nuclear proteins at amino acid residues of histidine and arginine, resulting in fluorescence enhancement by dozens of times. The developed R-CDs do not bind to DNA and would not cause genetic damage and will find various safe applications in biological and medical fields.

Development of a turn-on fluorescent probe for the imaging of intracellular hypochlorous acid (HClO) during ferroptosis

Ferroptosis is a burgeoning iron-dependent cell death form, and has close relation with hypochlorous acid (HClO). Exploring the fluctuation of the HClO level in living cells during ferroptosis could contribute to the profound study of the biological functions of HClO during ferroptosis. Here, we present a turn-on probe (RH-C) for the imaging of intracellular HClO during ferroptosis. The probe RH-C utilized the N,N-dimethylthiocarbamate group as a selective recognition site for HClO, and displayed desirable sensitivity and selectivity to HClO. The probe RH-C could detect the exogenous and endogenous HClO in living cells. Furthermore, RH-C was competent in monitoring the changes of endogenous HClO level during the process of ferroptosis. Biological imaging results suggested that erastin-induced ferroptosis can result in the excessive production of the endogenous HClO, and ferrostatin-1 (Fer-1) and vitamin E (VE) could block the massive accumulation of HClO in living cells.

Accurate detection depression cell model with a dual-locked fluorescence probe in response to noradrenaline and HClO

Due to the serious harm of depression to human health and quality of life, an accurate diagnosis of depression is warranted. For the complex etiology of depression, a single biomarker diagnostic method often leads to misdiagnosis. As noradrenaline and HClO are closely related to depression, a "dual-locked" fluorescence probe R-NE-HClO for diagnosing of depression through the simultaneous detection of noradrenaline and HClO was designed and synthesized. Fluorescence of R-NE-HClO can only be restored in the presence of both noradrenaline and HClO. The probe demonstrates excellent selectivity for noradrenaline and HClO and low cytotoxicity in cell imaging experiments. It is to be observed that we successfully applied the probe to accurately detect depressed cells which provides a possible tool for diagnosing depression.

Rational design of a ratiometric fluorescent nanoprobe for real-time imaging of hydroxyl radical and its therapeutic evaluation of diabetes

Hydroxyl radical (•OH), one of the most reactive and deleterious substances in organisms, belongs to a class of reactive oxygen species (ROS), and it has been verified to play an essential role in numerous pathophysiological scenarios. However, due to its extremely high reactivity and short lifetime, the development of a reliable and robust method for tracking endogenous •OH remains an ongoing challenge. In this work, we presented the first ratiometric fluorescent nanoprobe NanoDCQ-3 for •OH sensing based on oxidative C-H abstraction of dihydroquinoline to quinoline. The study mainly focused on how to modulate the electronic effects to achieve an ideal ratiometric detection of •OH, as well as solving the inherent problem of hydrophilicity of the probe, so that it was more conducive to monitoring •OH in living organisms. The screened-out probe NanoDCQ-3 exhibited an exceptional ratiometric sensing capability, better biocompatibility, good cellular uptake, and appropriate in vivo retention, which has been reliably used for detecting exogenous •OH concentration fluctuation in living cells and zebrafish models. More importantly, NanoDCQ-3 facilitated visualization of •OH and evaluation of drug treatment efficacy in diabetic mice. These findings afforded a promising strategy for designing ratiometric fluorescent probes for •OH. NanoDCQ-3 emerged as a valuable tool for the detection of •OH in vivo and held potential for drug screening for inflammation-related diseases.

Rational construction of reliable fluorescent probes for rapid detection and imaging evaluation of hazardous thiophenol in real-food and biosystems

Thiophenol (PhSH), a highly reactive aromatic thiol, plays an essential role as a common industrial raw material in food, pesticides, pharmaceuticals, and cosmetics. In this work, we designed and constructed two fluorescent probes CM-PhSH and CM-Ratio-PhSH by a rational strategy. Specifically, coumarin fluorophores with excellent optical properties were modified, and olefinic unsaturated bonds served as reaction sites for the detection of PhSH. Based on this, the introduction of the nitro group at specific positions of the CM-PhSH changed the fluorescence emission of the CM-Ratio-PhSH, eventually obtaining a novel ratiometric fluorescent probe CM-Ratio-PhSH for PhSH detection. Surprisingly, these two probes exhibited advantages such as high specificity and low limit of detection (LOD) for CM-PhSH 32.3 nM and CM-Ratio-PhSH 40.2 nM, respectively. Furthermore, subsequent experiments demonstrated CM-PhSH and CM-Ratio-PhSH could be successfully used for highly selective and rapid detection of PhSH in aqueous solutions, live cells, and complex food samples.

Colloidal Polymer Nanoparticles as Smart Inks for Authentication and Indication of Latent Fingerprints and Scratch

An environmentally friendly smart ink was developed by incorporating fluorescein into functionalized poly(methyl methacrylate) (PMMA) nanoparticles synthesized using an emulsifier-free emulsion copolymerization approach. The functional comonomers of 2-(dimethylamino)ethyl methacrylate (DMAEMA), acrylamide, hydroxyethyl methacrylate, and glycidyl methacrylate in 10 wt % with respect to methyl methacrylate were used to obtain the functionalized colloidal PMMA nanoparticles. Functional groups of the latex nanoparticles were characterized by Fourier-transform infrared spectroscopy. Field emission scanning electron microscopy results showed that all of the latex nanoparticles have nearly spherical morphologies with variations in size and surface smoothness due to the presence of different comonomers. Ultraviolet-visible and fluorescence spectra indicated that the fluorescein-doped latex nanoparticles containing the DMAEMA comonomer had the highest absorbance and fluorescence intensity. In the alkaline media, fluorescein turns to a dianion, showing a red shift and increased absorbance in the UV-vis spectroscopy. In addition, the electron inductive characteristics of the tertiary amine groups result in enhancing the conjugation of fluorescein molecules and increasing the fluorescence intensities. Therefore, the colloidal nanoparticles with amine functional groups were used in the formulation of a smart ink with applications in securing documents and fingerprints, encrypting banknotes and money, detecting latent fingerprints, crafting anticounterfeiting paper, and eventually providing optical detection and indication of surface scratches.

Coordination effect enhanced visualization of latent fingerprint with Eu (TTA)3phen-SiO2 microspheres

Latent fingerprint (LFP) powders are crucial in the detection of LFPs in forensic science. However, it is often plagued by poor image resolution and low contrast. Herein, enhanced LFP fluorescence (FL) visualizations are achieved by doping Eu(III) coordination compound Eu(TTA)3phen directly into SiO2 microspheres instead of Eu(III) ions. Using the synthesized Eu(TTA)3phen-SiO2 microspheres, the fine characteristic structure of LFP can be seen and recognized under 365 nm irradiation, up to Level 3. However, the Eu3+-SiO2 microspheres were difficult to recognize the Level 2,3 fingerprint structure. The difference between the ridge and furrow gray values of Eu(TTA)3phen-SiO2 microspheres is 2.1 times that of Eu3+-SiO2 microspheres. The coordination effect increased the asymmetry around Eu(III) ions, resulting in the ultrasensitive 5D0→7F2 transition, thus increasing the FL intensity, and the uniform doping of the Eu(III) coordination compound into SiO2 also reduced the surface FL quenching due to shielding from oxygen. Under this dual effect, the LFP performance of Eu(TTA)3phen-SiO2 microspheres has been significantly improved. We believe that this novel and easy LFP visualization method is a promising routine in specific target detection including criminal investigation, customhouse check-in, and drug control.

Real-time visualization of sulfatase in living cells and in vivo with a ratiometric AIE fluorescent probe

Different from the traditional enzymatic hydrolysis strategy, we rationally developed a ratiometric fluorescence probe DQMT-OH with AIE characteristics for sulfatase detection utilizing the "Lock-Key" strategy. It can be successfully used to monitor sulfatase in living cells and in vivo through different fluorescent channels with good cell permeability and low cytotoxicity.

A dicyanoisophorone-based ICT fluorescent probe for the detection of Hg2+ in water/food sample analysis and live cell imaging

Mercury ions are notoriously difficult to biodegradable, and its abnormal bioaccumulation in the human body through the food chain can cause various diseases. Therefore, the quantitative and real-time detection of Hg²⁺ is very extremely important. Herein, we have brilliant designed and synthesized (E)-O-(4-(2-(3-(dicyanomethylene)-5,5-dimethylcyclohex-1-en-1-yl)vinyl)phenyl) O-phenyl carbonothioate (ICM-Hg) as a selective fluorescent probe for Hg²⁺ detection in real samples and intracellular staining. ICM-Hg displayed high specificity toward Hg²⁺ by activating the intramolecular charge transfer (ICT) process, resulting in distinguished color change from colorless to bright yellow along with noticeable switch on yellow fluorescence emission. The fluorescent intensity of ICM-Hg at 585 nm shows a well linear relationship in the range of Hg²⁺ concentration (0-45 μM), and the detection of limit for Hg²⁺ is calculated to be 231 nM. Promisingly, ICM-Hg can efficiently detect Hg²⁺ in real samples including tap water, tea, shrimp, and crab with quantitative recovery as well as the intracellular fluorescence imaging.

High-definition and robust visualization of latent fingerprints utilizing ultrabright aggregation-induced emission of iridium developer

Creation of AIEgens with high brightness is compactly related to acquiring optimum AIE capabilities and still faces challenges. This study proposes an ingenious structurally regulative approach for preparing ultrabright AIEgens, taking iridium complexes as the model. The incremental rotational activity of substituents obtained by fine adjustment of the stereoscopic configuration efficaciously activates the AIE of iridium complexes and synchronously imparts high-brightness luminescence. Subsequently, benefitting from the ultrabright AIE, high-resolution visualization of latent fingerprints (LFPs) is achieved on diverse substrates by transient immersion in a solution of the AIE-active iridium complex (Ir3) for 60 s. The LFPs stained by Ir3 are integral and distinct enough to possess level 1-3 detail features, which allow precisely realizing personal identification. The LFP photograph emerges inconspicuous attenuation of contrast when aged under ambient light for 10 days and then being continuously irradiated with high-power ultraviolet light for 1 h, reflecting extraordinary aging resistance. Notably, the ultrabright AIE of Ir3 with room-temperature phosphorescence feature successfully achieves enhanced visualization of local fingerprint details with ultrahigh contrast. This LFP visualization protocol based on the ultrabright AIEgens is practical and provides a reliable solution for forensic investigations in actual scenarios.

An activatable nanoprobe based on nanocomposites of visible-light-excitable europium(III) complex-anchored MnO2 nanosheets for bimodal time-gated luminescence and magnetic resonance imaging of tumor cells

Bimodal imaging probes that combine magnetic resonance imaging (MRI) and photoluminescence imaging are quite appealing since they can supply both anatomical and molecular information to effectively ameliorate the accuracy of detection. In this study, an activatable nanoprobe, [Eu(BTD)₃(DPBT)]@MnO₂, for bimodal time-gated luminescence imaging (TGLI) and MRI has been constructed by anchoring visible-light-excitable Eu³⁺ complexes on lamellar MnO₂ nanosheets. Due to the luminescence quenching effect and non-magnetic resonance (MR) activity of MnO₂ nanosheets, the developed nanoprobe presents quite weak TGL and MR signals. After exposure to H₂O₂ or GSH, accompanied by the transformation from MnO₂ to Mn²⁺, the nanoprobe exhibits rapid, sensitive, and selective "turn-on" responses towards GSH and H₂O₂ in TGL and MR detection modes. Furthermore, the nanoprobe displays high stability, low cytotoxicity, good biocompatibility and water dispersion. Given the high contents of GSH and H₂O₂ in cancer cells, the nanoprobe was used for the identification of cancer cells by TGLI of intracellular GSH and H₂O₂, as well as for the tracing of tumor cells in tumor-bearing mice by tumor-targeting in vivo MRI and TGLI of tumor tissues. The research outcomes proved the potential of [Eu(BTD)₃(DPBT)]@MnO₂ as a useful nanoprobe for the tracing and accurate detection of cancer cells in vitro and in vivo via bimodal TGLI and MRI.

Multi-Stimuli-Responsive Amphiphilic Pyridinium Salt and Its Application in the Visualization of Level 3 Details in Latent Fingerprints

Organic luminescent materials that can simultaneously achieve multimode mechanochromism and its water-vapor-induced recovery are desirable for practical applications but rarely reported. Herein, an amphiphilic compound, 4-(9H-carbazol-9-yl)-1-(2-hydroxyethyl)pyridin-1-ium bromide (CPAB), is designed by integrating a lipophilic aromatic unit and hydrophilic end in the molecular architecture. Self-recovered mechanochromism from brown to cyan is observed upon mechanical grinding in air. Comprehensive research by X-ray diffraction, infrared spectroscopy, and single-crystal analysis reveals that the photoluminescence switch originates from the variation in intermolecular hydrogen bonds and molecular packing mode. The amphiphilic nature of CPAB allows water molecules to enter the crystalline lattice, forming two polymorphs of the crystalline phase, namely CPAB-D and CPAB-W. The hydrosoluble CPAB exhibits excellent capability in probing the level 3 details of fingerprints because its lipophilic part can target the fatty acid residues of fingerprints, leading to strong aggregation-induced fluorescence. The research may inspire the design of latent fingerprint developers and application in forensics/anti-counterfeiting.

Triphenylamine-Modified Cinnamaldehyde Derivate as a Molecular Sensor for Viscosity Detection in Liquids

Liquid safety is considered a serious public health problem; a convenient and effective viscosity determination method has been regarded as one of the powerful means to detect liquid safety. Herein, one kind of triphenylamine-modified cinnamaldehyde-based fluorescent sensor (3-(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl)acrylaldehyde (DPABA)) has been developed for sensing viscosity fluctuations in a liquid system, where a cinnamaldehyde derivative was extracted from one kind of natural plant cinnamon and acted as an acceptor, which has been combined with a triphenylamine derivate via the Suzuki coupling reaction within one facile step. Twisted intramolecular charge transfer (TICT) was observed, and the rotation could be restricted in the high-viscosity microenvironment; thus, the fluorescent signal was released at 548 nm. Featured with a larger Stokes shift (223.8 nm in water, 145.0 nm in glycerol), high adaptability, sensitivity, selectivity, and good photostability, the capability of high signal-to-noise ratio sensing was achieved. Importantly, this sensor DPABA has achieved noninvasively identifying thickening efficiency investigation, and viscosity fluctuations during the liquid deterioration program have been screened as well. We believed that this unique strategy can accelerate intelligent molecular platforms toward liquid quality and safety inspection.

Water-soluble fluorescent probes for differentiating cancer cells and normal cells by tracking lysosomal viscosity

Lysosomal viscosity is a significant parameter of lysosomes and closely related to various diseases. Herein, two fluorescent probes, Lyso-vis-A and Lyso-vis-B, were developed, which demonstrate diverse advantages, including great water solubility, lysosome targeting ability and viscosity sensitivity. In particular, Lyso-vis-A exclusively showed fluorescence response toward viscosity but was not influenced by pH changes, rendering it a selective lysosomal viscosity probe. Furthermore, Lyso-vis-A was successfully applied to monitor lysosomal viscosity variations in living cells and differentiate cancer cells and normal cells.

A Mitochondria-Targeted Fluorescent Probe for Monitoring NADPH Overproduction during Influenza Virus Infection

Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is an important cofactor in the progress of antioxidant synthesis and biosynthesis, and an abnormal NADPH level has been observed in many viral infection processes. However, efficient tools to monitor NADPH in living cells after viral infection have not been reported. In this work, we present a fluorescent probe, NAFP4, that could detect NADPH ex vivo with a low detection limit of 3.66 nM and image mitochondrial NADPH level changes in living cells. The probe exhibits excellent cell permeability, rapid reactivity, and high selectivity with minimal cytotoxicity. Using NAFP4, we reveal that the NADPH is overproduced in the host cells infected by influenza virus, which was caused by an elevated level of G6PDH during the virus infection. Moreover, there was positive association between the G6PDH level and virus replication. With the proposed probe NAFP4, our study highlights that the virus infection would influence the host metabolism in NADPH production and also suggests that G6PDH is expected to be a promising target for antiviral therapy.

Aggregation-induced emission-active micelles: synthesis, characterization, and applications

Aggregation-induced emission (AIE)-active micelles are a type of fluorescent functional materials that exhibit enhanced emissions in the aggregated surfactant state. They have received significant interest due to their excellent fluorescence efficiency in the aggregated state, remarkable processability, and solubility. AIE-active micelles can be designed through the self-assembly of amphipathic AIE luminogens (AIEgens) and the encapsulation of non-emissive amphipathic molecules in AIEgens. Currently, a wide range of AIE-active micelles have been constructed, with a significant increase in research interest in this area. A series of advanced techniques has been used to characterize AIE-active micelles, such as cryogenic-electron microscopy (Cryo-EM) and confocal laser scanning microscopy (CLSM). This review provides an overview of the synthesis, characterization, and applications of AIE-active micelles, especially their applications in cell and in vivo imaging, biological and organic compound sensors, anticancer drugs, gene delivery, chemotherapy, photodynamic therapy, and photocatalytic reactions, with a focus on the most recent developments. Based on the synergistic effect of micelles and AIE, it is anticipated that this review will guide the development of innovative and fascinating AIE-active micelle materials with exciting architectures and functions in the future.

Dual-Responsive Benzo-Hemicyanine-Based Fluorescent Probe for Detection of Cyanide and Hydrogen Sulfide: Real-Time Application in Identification of Food Spoilage

Colorimetric and fluorescent probes have received a lot of attention for detecting lethal analytes in realistic systems and in living things. Herein, a dual-approachable Benzo-hemicyaninebased red-emitting fluorescent probe PBiSMe, for distinct and instantaneous detection of CN^- and HS^- was synthesized. The PBiSMe emitted red fluorescence (570 nm) can switch to turn-off (570 nm) and blue fluorescence (465 nm) in response to CN^- and HS^-, respectively. Other nucleophilic reagents, such as reactive sulfur species (RSS) and anions, have no contact or interference with the probe; instead, a unique approach is undertaken to exclusively interact with CN^- and HS^- over a wide pH range. The measured detection limits for CN^- (0.43 μM) and HS^- (0.22 μM) ions are lower than the World Health Organization's (WHO) recommended levels in drinking water. We confirmed 1:1 stoichiometry ratio using Job's plot and observed good quantum yield for both analytes. The probe-coated paper strips were used to detect the H₂S gas produced by food spoilage (such as eggs, raw meat, and fish) via an eye-catching visual response. Moreover, fluorescence bioimaging studies of living cells was done to confirm the probe's potential by monitoring the presence of CN^- and HS^- in a living system.

Novel 2-Benzo[d]thiazolyl-4-quinolinylphenol Skeleton-Based Turn-on Fluorescent Probe for H2S Detection and its Multiple Applications in Water Environment, Foodstuffs, and Living Organisms

Hydrogen sulfide (H₂S) has comprehensive contributions to maintaining the normal operation and stability of organisms, and it also occurs in the wastewater environment and is related to the deterioration of foodstuffs. Therefore, developing high-sensitive detection techniques for tracing H₂S is promising and meaningful. Inspired by this, a novel nopinone-based fluorescent probe NPS for the recognition of H₂S was designed and synthesized with excellent sensitivity, low limit of detection (79 nM), good selectivity, and wide pH range (5-9). NPS could emit strong yellow fluorescence and its emission intensity showed a remarkable augmentation at 520 nm upon the supplement of H₂S. Furthermore, the recognition mechanism of NPS for H₂S was verified by the HRMS analysis, ¹H NMR spectra titration, and DFT computation. What is more, NPS also had broad applications in the monitoring of real water samples, red wine, beer, and eggs samples, which showed its development prospect and value in environmental pollution, foodstuffs quality analysis fields. NPS also was applied to monitor trace exogenous H₂S and bioimaging in living cells and zebrafish.

Multifunctional fluorescent Eu-MOF probe for tetracycline antibiotics and dihydrogen phosphate sensing and visualizing latent fingerprints†‡

The contamination of tetracycline antibiotics and dihydrogen phosphate (H₂PO₄⁻) in food and the environment is one of the major concerns for human health. Herein, a water-stable carboxyl-functionalized europium metal–organic framework (Eu-MOF) was prepared and demonstrated, for the first time, as a dual-responsive fluorescent sensor of tetracycline antibiotics (oxytetracycline (OTC), tetracycline (TC), and doxycycline (DOX)) and H₂PO₄⁻via fluorescent turn-on and turn-off, respectively. Eu-MOF presents a sensitive and selective detection of OTC with a rapid response time (1 min) and good anti-interference ability. The limits of detection (LODs) of 78 nm, 225 nm, and 201 nM were achieved for OTC, TC, and DOX, respectively. Coordination and hydrogen bonding led to energy and electron transfer from the TC to the MOF, contributing to the fluorescent enhancement mechanism. Moreover, Eu-MOF can effectively detect H₂PO₄⁻via fluorescence turn-off with a LOD of 0.70 μM. The interactions between H₂PO₄⁻ and MOF interrupt the energy transfer from ligand to MOF, leading to fluorescence quenching. In addition, Eu-MOF was successfully applied to determine OTC and H₂PO₄⁻ in real samples, obtaining satisfactory recoveries and RSDs. More fascinating, Eu-MOF could be utilized to develop latent fingerprints on various surfaces, providing well-defined fluorescent fingerprint details in which the sweat pores can be seen with the naked eye.

Water-stable Eu-MOF as a fluorescent probe for detecting tetracycline antibiotics and dihydrogen phosphate in real samples and visualization of latent fingerprints.

Novel Colorimetric and NIR Fluorescent Probe for Bisulfite/Sulfite Detection in Food and Water Samples and Living Cells Based on the PET Mechanism

Despite their status of being widely used as food additives, bisulfite (HSO₃^-)/sulfite (SO₃^2-) can pose serious health risks when they are excessively added. Therefore, it is vital to develop a new method for detecting HSO₃^-/SO₃^2- in foodstuff. In this paper, a benzopyran-benzothiazole derivative (probe DCA-Btl) with near-infrared emission was designed and synthesized by constructing a "push-pull" electronic system. DCA-Btl can selectively recognize HSO₃^-/SO₃^2- via a colorimetric and fluorescence dual channel in DMF/PBS (1:1, v/v, pH = 8.4), and the emission wavelength of DCA-Btl can reach 710 nm. The fluorescence quenching of DCA-Btl after recognition of HSO₃^- is attributed to the photoinduced electron transfer (PET) process of the adduct DCA-Btl-HSO₃^- as evaluated by the DFT/TD-DFT method. In addition, DCA-Btl has many advantages, including a large Stokes shift (95 nm), good anti-interference ability, and little cytotoxicity. What's more, DCA-Btl has been successfully applied for the detection of HSO₃^-/SO₃^2- in actual water samples and food samples such as sugar, red wine, and biscuits with satisfying results, as well as for fluorescent imaging of HSO₃^- in living MCF-7 cells.

A fluorescent molecular rotor for the in situ imaging of latent fingerprints

We developed a fluorescent molecular rotor that responds to hydrophobic and viscous environments and visualizes latent fingerprints with level 3 details.