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Introduction: The construction of nanomaterial-based ratiometric detection systems usually requires covalent modification, which undergoes reactive environments and may change the natural properties of supporting nanomaterials. Methods: In this study, dualemissive and fluorescein-decorated gold nanoclusters (F-Au NCs) through cyclodextrin-supported host–guest interaction (non-covalent modification) are explored as ratiometric Hg2+ nanoprobes through d10–d10-interactioncaused fluorescence quenching of Au NCs. Results and Discussion: The fluorescein decoration only provides a fluorescent internal reference but does not change the Hg2+-Au NCs affinity nature. Ratiometric and selective Hg2+ detection is achieved through the proposed F-Au NC probes with a limit of detection of 15 nM. The Hg2+ analysis in river water samples with small relative standard deviations validates the practical application of these probes. [ABSTRACT FROM AUTHOR]

The important role to neuron communication and brain functions makes the selective and accurate detection of dopamine (DA, a typical neurotransmitter) significant. In this study, a morin‐based probe has been reported for the ratiometric DA detection. The mechanism study discloses that the inside resorcinol motif can specifically react with DA and form fluorescent azamonardine‐like product. In addition, the intrinsic emission from the internal chromophore endows ratiometric variation. With these features, selective DA sensing is realized using morin probe with a limit of detection of 2.2 nM (S/N = 3). Moreover, the practical application of the proposed method is further validated by the accurate DA determination in urine samples. This work demonstrates the possible exploration of novel small molecule‐based ratiometric‐sensing systems toward various analytes with the combination of proper reaction motif and chromophore. It is expected that the development of versatile probes for the ratiometric and accurate recognition of environmental and biological markers can refer such a design strategy. [ABSTRACT FROM AUTHOR]

It is essential to probe the coordination number (CN) because it is a crucial factor to ensure the catalytic capability of single‐atom catalysts (SACs). Currently, synchrotron X‐ray absorption spectroscopy (XAS) is widely used to measure the CN. However, the scarcity of synchrotron X‐ray source and complicated data analysis restrict its wide applications in determining the CN of SACs. In this contribution, we have developed a d‐band center‐regulated acetone cataluminescence (CTL) probe for a rapid screening of the CN of Pt‐SACs. It is disclosed that the CN‐triggered CTL is attributed to the fact that the increased CN could induce the downward shift of d‐band center position, which assists the acetone adsorption and promotes the subsequent catalytic reaction. In addition, the universality of the proposed acetone‐CTL probe is verified by determining the CN of Fe‐SACs. This work has opened a new avenue for exploring an alternative to synchrotron XAS for the determination of CN of SACs and even conventional metal catalysts through d‐band center‐regulated CTL. [ABSTRACT FROM AUTHOR]

It is essential to probe the coordination number (CN) because it is a crucial factor to ensure the catalytic capability of single‐atom catalysts (SACs). Currently, synchrotron X‐ray absorption spectroscopy (XAS) is widely used to measure the CN. However, the scarcity of synchrotron X‐ray source and complicated data analysis restrict its wide applications in determining the CN of SACs. In this contribution, we have developed a d‐band center‐regulated acetone cataluminescence (CTL) probe for a rapid screening of the CN of Pt‐SACs. It is disclosed that the CN‐triggered CTL is attributed to the fact that the increased CN could induce the downward shift of d‐band center position, which assists the acetone adsorption and promotes the subsequent catalytic reaction. In addition, the universality of the proposed acetone‐CTL probe is verified by determining the CN of Fe‐SACs. This work has opened a new avenue for exploring an alternative to synchrotron XAS for the determination of CN of SACs and even conventional metal catalysts through d‐band center‐regulated CTL. [ABSTRACT FROM AUTHOR]

Gold nanoclusters (Au NCs) with bright emission and unique chemical reactivity characters have been widely applied for optical sensing and imaging. With a combination of surface modifications, effective therapeutic treatments of tumors are realized. In this review, we summarize the recently adopted biosensing and therapy events based on Au NCs. Homogeneous and fluorometric biosensing systems toward various targets, including ions, small molecules, reactive oxygen species, biomacromolecules, cancer cells, and bacteria, in vitro and in vivo, are presented by turn-off, turn-on, and ratiometric tactics. The therapy applications are concluded in three aspects: photodynamic therapy, photothermal therapy, and as a drug carrier. The basic mechanisms and performances of these systems are introduced. Finally, this review highlights the challenges and future trend of Au NC-based biosensing and therapy systems. [ABSTRACT FROM AUTHOR]

The development of green and simple chemiluminescence (CL) systems with intensive and long‐lasting emission is highly desirable in lighting and extension of their applications. In this study, it is found that the involvement of aggregation‐induced emission (AIE) surfactant could greatly enhance the CL of luminol–H2O2–Co2+ system. The inserted hydrophobic tetraphenylethylene fluorophore in AIE is able to increase the hydrophobicity of alkyl chain and decrease the critical micelle concentration (CMC) of surfactant. The synergistic effect of micelle‐improved enrichment and CL resonance energy transfer endows luminol–H2O2–Co2+ system intensive and long‐lasting emission under neutral pH conditions (pH 7.4). The visible emission is still observed even after 60 min. Our study has opened a new avenue for exploring green and simple effective CL systems through AIE surfactant with unltralow CMC toward various applications in lighting, optical sensing, and photocatalysis, etc. [ABSTRACT FROM AUTHOR]

The Journal of the Chinese Chemical Society has published a special issue on "Frontier Precise Measurement," which explores the advancements and applications of precision measurement in various fields of analytical chemistry. The issue features articles on topics such as extraction, spectroscopy, sensors, electrochemical detection, mass spectrometry, and software development. The articles highlight innovative methodologies and technologies, including the synthesis and purification of theaflavins, magnetic solid phase adsorption techniques, genomic DNA extraction methods, and the use of magnetic nanocomposites for solid phase extraction. The issue also covers sensor-related articles on detection methods, as well as articles on mass spectrometry and software development. The authors express gratitude to the contributors and hope that readers will find the content inspiring for their future research endeavors. [Extracted from the article]

Copper ion (Cu2+) is a highly toxic environmental pollutant with bioaccumulative properties, making its rapid and selective detection important for environmental and health monitoring. In this study, highly fluorescent carbon nanodots by the electrolysis of Congo Red are developed, which are denoted as CR‐CDs and exhibit high quantum yield and pH‐responsive character. The pH response behavior is applied for pH test in soft drinks with high accuracy. Cu2+ causes dramatic fluorescence quenching due to the formation of cupric amine complex and the occurrence of inner filter effect. The signal changes in fluorescence spectroscopy allow a detection limit of Cu2+ at 0.13 μM. The response is highly specific toward Cu2+ over other metal ions. In addition, the practicability of the sensor is validated by accurate Cu2+examination in running water samples. [ABSTRACT FROM AUTHOR]

There is an on-going demand in recent years for safer and "greener" hair coloring agents with the global consumer awareness of the adverse effects of synthetic hair dyes. The belief in sustainability and health benefits has focused the attention of the scientific community towards natural colorants that serve to replace their synthetic toxic counterparts. This review article encompasses the historical applications of a vast array of natural plant hair dyes and summarizes the possible coloration mechanisms (direct dyeing and mordant dyeing). Current information on phytochemicals (quinones, tannins, flavonoids, indigo, curcuminoids and carotenoids) used for hair dyeing are summarized, including their botanical sources, color chemistry and biological/toxicological activities. A particular focus is given on research into new natural hair dye sources along with eco-friendly, robust and cost-effective technologies for their processing and applications, such as the synthetic biology approach for colorant production, encapsulation techniques for stabilization and the development of inorganic nanocarriers. In addition, innovative in vitro approaches for the toxicological assessments of natural hair dye cosmetics are highlighted. [ABSTRACT FROM AUTHOR]

Polymer-surfactant interaction decides the performance of corresponding complexes, making its rapid and intuitionistic visualization important for enhancing the performance of products and/or processing in related fields. In this study, the fluorescence visualization of the interaction between cationic hyperbranched polyethyleneimine and anionic sodium dodecyl sulfonate surfactant was realized by dual-emissive gold nanocluster labeling. The sensing mechanism was due to the interaction-induced polymer conformation change, which regulated the molecular structure and subsequent photoradiation process of the gold nanoclusters. All three inflection points of the interactions between the polymers and the surfactants were obtained by the change in fluorescence emission ratio of the designed dual-emissive gold nanoclusters. Moreover, these inflection points are verified by the hydrodynamic diameter and zeta potential measurements. [ABSTRACT FROM AUTHOR]

Thiolate‐stabilized gold nanoclusters (Au NCs) are widely used in bioimaging, chemical sensing, and emitting devices because of their good solubility, great stability and versatile optical/chemical properties. However, most conventional synthetic strategies reported so far suffer long reaction time, which limits the rapid and large‐scale synthesis of Au NCs. In this study, a simple electrostatic attraction‐assisted core approaching strategy was developed, which accelerates the synthesis of Au NCs by introducing polyamine (hyperbranched polyetheneimine, hPEI). As a case study, the tactic was demonstrated for the rapid preparation of Au NCs based on glutathione (GSH)‐HAuCl4 system within 1.5 h. The synthesis includes two steps: first, negatively charged Au(I)‐GSH complex under basic condition (pH 9) was adsorbed onto hPEI surface via electrostatic attraction; second, aurophilic attraction of Au(I) centers benefited the formation of Au NCs. With such a strategy, copper nanoclusters (Cu NCs) can also be quickly prepared within 30 min. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) with excellent biocompatibility, tunable emission and designable surface composition have been widely applied for luminescent sensing of diverse biological targets. In addition to homogeneous bioanalysis, dynamic bioanalysis of biological analytes is also achieved with the combination of single‐particle imaging technique. In this review, we majorly conclude the recently adopted steady‐state and dynamic bioanalysis based on CQD luminescence probes. The synthesis and luminescence mechanism of CQDs is first introduced. Regarding the CQD‐based luminescent bioanalysis, sensing principles and tactics are provided. The steady‐state bioanalysis systems are discussed according to the targets. Dynamic bioanalysis platforms are concluded in two aspects: time‐dependent accumulation and real‐time dynamics. This review ends with the discussion of challenges and future trends of CQD probe‐based luminescent bioanalysis. [ABSTRACT FROM AUTHOR]

Near‐infrared persistent phosphors (NIR‐PPs) are an emerging category of luminescent materials that can continuously emit NIR luminescence with super‐long decay time of minutes, hours, or even days after the excitation ceases. Their unique excitation‐free long‐lasting afterglow, together with the NIR emission, has not only attracted wide research interests in the areas of photochemistry, photophysics, spectroscopy, and materials science, but also stimulated advanced applications in biosensing, bioimaging, biomedicine, and therapy in the past decade. Beyond these bio‐related applications, the active research field triggers a number of novel applications recently. In this review, a brief outline of NIR‐PPs including the luminescence mechanism, main material systems, and how they were applied into various fields was depicted. Particular emphasis was put on the emerging applications outside the field of biology. Future perspectives in this exploration research area were also presented. We hope this review can help researchers grab the latest information in the fast‐growing field of NIR‐PPs. [ABSTRACT FROM AUTHOR]

The detection of cyanide anion (CN−), a highly toxic pollutant, has attracted growing attention in the past years. In this work, a nanosensor composed of hyperbranched polyethyleneimine (hPEI)-assisted dual-emissive gold nanoclusters (DE-Au NCs) is proposed for ratiometric detection of CN− based on surface valence state-driving etch. The ratiometric color change of fluorescence is based on a fact that the red-emissive Au NCs with a high content of surface Au(I) can be easily etched by CN−, while the blue-emissive Au NCs with nearly neutral character can resist CN−. Because of the specific gold-CN− chemistry and electrostatic attraction between the positively charged hPEI protecting layer and the negatively charged CN−, the DE-Au NC-based nanosensor provides high selectivity toward CN− over other anions with a limit of detection of 10 nM. Practical application of the proposed DE-Au NC nanosensor is verified by satisfying recoveries of CN− determination in river water and urine samples. [ABSTRACT FROM AUTHOR]

Plasmonic nanoparticles with special localized surface plasmon resonance (LSPR) characters have been widely applied for optical sensing of various targets. With the combination of single nanoparticle imaging techniques, dynamic information of reactions and biological processes is obtained, facilitating the deep understanding of their principle and design of outstanding nanomaterials. In this review, we summarize the recently adopted optical analysis of diverse analytes based on plasmonic nanoparticles both in homogeneous solution and at the single-nanoparticle level. A brief introduction of LSPR is first discussed. Colorimetric and fluorimetric homogeneous detection examples by using different sensing mechanisms and strategies are provided. Single plasmonic nanoparticle-based analysis is concluded in two aspects: visualization of chemical reactions and understanding of biological processes. The basic sensing mechanisms and performances of these systems are introduced. Finally, this review highlights the challenges and future trend of plasmonic nanoparticle-based optical analysis systems. [ABSTRACT FROM AUTHOR]

In present study, we discovered unusual solvent-mediated aggregation-enhanced emission (AEE) character of 11-mercaptoundecanoic acid capped gold nanoclusters (MUA-Au NCs). When aggregated in aqueous media, the MUA-Au NCs showed strong emission, which was weakened by adding ethanol. Interestingly, the suppressed emission was selectively enhanced in the presence of hydrogen sulfide (H2S) because H2S was absorbed onto Au NCs through the strong sulfur-gold bonding affinity. The hydrolyzed H2S, namely, HS−, made the Au NCs negatively charged, which aggregated again due to decreased solubility. The H2S-mediated fluorescence enhancement can be further amplified by introducing a hydrophilic thiolate (glutathione, GSH) onto the surface of Au NCs (GSH/MUA-Au NCs), which enabled sensitive determination of H2S. Under the optimized condition, a detection limit of 35 nM was achieved. The determination was not interfered by other anions such as F−, Cl−, Br−, I−, OAc−, N3−, NO3−, HCO3−, SCN−, SO32−, and SO42−. This excellent sensing performance allowed practical application of the GSH/MUA-Au NC-based sensing platform to accurate determination of H2S in human serum samples. [ABSTRACT FROM AUTHOR]

The exploitation of highly soluble and responsive AIEgens is essential for further expansion of their practical applications. In this study, dipropyltrimethylammonium bromide-substituted TPE (denoted as o-TPEDTA), a homolateral and dicationic AIEgen, was synthesized and applied for the turn-on detection of casein via hydrophobic interactions. The rapid and sensitive detection of casein was achieved using the designed o-TPEDTA probe with the limit of detection of 0.05 μg mL−1. The satisfying selectivity of over 1000-fold concentration of other probably existing chemicals, including amino acids, sugars and salts, was achieved due to the strong binding affinity between o-TPEDTA and casein. The evaluation of casein in milk powder samples with small relative standard deviations was realized using the o-TPEDTA probe. The accuracy of the o-TPEDTA probe-based detection method was validated by the consistency of the casein detection results with those obtained via a national standard casein evaluation approach. [ABSTRACT FROM AUTHOR]

Luminol tablet–Tris–Co(ii) complex–PVP–H2O2 systems exhibit 13 hours of intensive and stable chemiluminescence (CL) due to the continuous generation of ṖOH and sustained-release. Multicolored chemical lights were prepared through CL resonance energy transfer. This work presents a new method for the fabrication of bright chemical lights in aqueous solution for emergencies. [ABSTRACT FROM AUTHOR]

We proposed a π-conjugation enhanced molar absorption coefficient strategy that can effectively improve the sensitivity of the spectrophotometry sensing technique. As a case study, the strategy was demonstrated for sensitive nitrite detection based on the typical nitrite–thiol reaction. [ABSTRACT FROM AUTHOR]

In this study, we prepared photoluminescent l-cysteine (Cys)-capped gold nanoclusters (Cys–Au NCs) via NaBH4-mediated reduction of aggregated coordination polymers (supramolecules) of –[Cys–Au(i)]n–. The –[Cys–Au(i)]n– supramolecules with interesting chiral properties were formed through simple reactions of chloroauric acid (HAuCl4) with Cys at certain pH values (pH 3–7). The –[Cys–Au(i)]n– polymers could self-assemble into –[Cys–Au(i)]n– supramolecules with irregular morphologies and diameters larger than 500 nm through stacked hydrogen bonding and zwitterionic interactions between Cys ligands and through Au(i)…Au(i) aurophilic interactions in solutions with pH values ≤7. The photoluminescent Au NCs (quantum yield = 11.6%) dominated by a Au13 core were embedded in –[Cys–Au(i)]n– supramolecules after NaBH4-mediated reduction. The optical and structural properties of Cys–Au NCs/–[Cys–Au(i)]n– nanocomposites were investigated, revealing that the interaction between Cys ligands plays a critical role in the self-assembly of –[Cys–Au(i)]n– supramolecules and in the formation of photoluminescent Cys–Au NCs embedded in the supramolecules. To further demonstrate that the photoluminescence properties and structures of the nanocomposites are mediated by the intermolecular forces of thiol ligands, other thiol ligands (l-penicillamine, l-homocysteine, 3-mercaptopropionic acid, and l-glutathione) and a ligand-crosslinking agent [bis(sulfosuccinimidyl) suberate; BS3] were used. We concluded that the electrostatic interactions, hydrogen bonding and steric effects dominate the polymer self-assembly into thiol-ligand–Au(i) supramolecules and thus the formation of Au NCs. Our study provides insights into the bottom-up synthesis of photoluminescent Au NCs from thiol-ligand–Au(i) complexes, polymers, and supramolecules. The hybrid Au NCs/–[Cys–Au(i)]n– nanocomposites can potentially be employed as drug carriers and bioimaging agents. [ABSTRACT FROM AUTHOR]

Cataluminescence (CTL) is a specific chemiluminescence (CL) occurring on the surface of solid catalysts during heterogeneous catalytic oxidation reactions, and it is still a young technique compared to conventional CL. In recent years, CTL-based sensors have been widely used in the detection of various analytes. We have witnessed many developments in CTL-based sensing systems for the enhancement of sensitivity or selectivity. This review provides a thorough introduction to the history and development of CTL-based sensing systems. We have briefly discussed the working principles for CTL systems and related the influencing factors first. The development of CTL based on these factors and instruments has been subsequently introduced. Several excellent CTL-based sensing systems have been discussed to highlight their practicality for the analysis of complicated environmental samples. Discussions of the challenges and future trends of CTL-based sensing systems have been provided in the end of this review. [ABSTRACT FROM AUTHOR]

In the last two decades nanoparticles have been widely applied to enhance chemiluminescence (CL). The morphology of nanoparticles has an important influence on nanoparticle-amplified CL. However, studies of nanoparticle-amplified CL focus mainly on the size and shape effects, and no attempt has been made to explore the influence of uniformity in nanoparticle-amplified CL processes. In this study we have investigated nanoparticle uniformity in the luminol-HO CL system using layered double hydroxides (LDHs) as a model material. The results demonstrated that the uniformity of LDHs played a key role in CL amplification. A possible mechanism is that LDHs with high uniformity possess abundant catalytic active sites, which results in high CL intensity. Meanwhile, the sensitivity for HO detection was increased by one order of magnitude (1.0 nM). Moreover, the uniform-LDH-amplified luminol CL could be applied to selective detection of glucose in human plasma samples. Furthermore, such a uniformity-dependent CL enhancement effect could adapted to other redox CL systems-for example, the peroxynitrous acid (ONOOH) CL system. [ABSTRACT FROM AUTHOR]

Layered nanomaterial has become a popular hierarchical material for amplifying chemiluminescence (CL) in recent years, mainly because of its ease of preparation and modification, large specific surface area, and high catalytic activity. In this review, we mainly discuss layered-nanomaterial-amplified CL systems based on graphene and its derivatives, layered double hydroxides, and clay. Detection mechanisms and strategies of layered-nanomaterial-amplified CL systems are provided to show the basic concepts for designing sensitive and selective sensing systems. Strategies for expanding the applications of layered-nanomaterial-amplified CL systems by combination with surfactants, quantum dots, organic dyes, and nanoparticles are introduced for the analysis of various analytes in real samples. The challenges and future trends of layered-nanomaterial-amplified CL systems are discussed at the end of the review. [ABSTRACT FROM AUTHOR]

The ratio of reduced and oxidized glutathione (GSH/GSSG ratio) is a greater first indication of disease risk than the total concentration of GSH. However, the interferences from thiolated biomolecules, especially cysteine (Cys), make the accurate detection of GSH/GSSG ratio a technical problem. In this work, we successfully used a mixture of quantum dots (QDs) and ZnAl-LDH nanosheets to fabricate a high electrochemiluminescence resonance energy transfer (ERET) efficiency sensor for GSH from the disturbances of amino acids, especially Cys and GSSG. The mechanisms of high ERET efficiency and selectivity were well investigated with spectroscopy analysis and theoretical calculation. The results showed that the interaction force between ZnAl-LDH nanosheets and molecules proved a long-range-ordered space and selective transmission for molecules. On the basis of these interesting phenomena, we successfully measured the GSH/GSSG ratio in whole blood and serum samples. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (Au NPs) have become one of the most popular materials for sensing of analytes of interest in the last decade, mainly because of their ease in preparation and conjugation, stability, biocompatibility, and size-dependent optical properties. We have witnessed many sensitive and selective Au NP based optical systems for the quantitation of metal ions, anions, proteins, and DNA, based on analyte induced changes in their absorption, fluorescence, and scattering. In this tutorial review, we briefly discuss wet chemical approaches for the preparation of Au NPs. Sensing mechanisms and strategies of Au NP based optical systems are provided to show basic concepts in designing sensitive and selective sensing systems. Strategies for signal amplification applied in Au NP based systems are emphasized for the analysis of trace amounts of analytes in real samples. Many excellent Au NP based optical sensing systems are discussed to highlight their practicality for the analysis of complicated biological and environmental samples. The tutorial review ends with the discussion of the challenges and future trends of Au NP based optical sensing systems. [ABSTRACT FROM AUTHOR]

As a well-known environmental pollutant but also an important gaseous transmitter, the specific detection of hydrogen sulfide (H2S) is significant in biological systems. In this study, fluorosurfactant functionalized gold nanorods (FSN-AuNRs) have been proposed to act as selective colorimetric nanoprobes for H2S. With the combination of strong gold–S interactions and small FSN bilayer interstices, FSN-AuNRs demonstrate favorable selectivity and sensitivity toward H2S over other anions and small biological molecules. The practical application of the present method in biological H2S detection was validated with human and mouse serum samples. Moreover, the proposed nanoprobe can also be used for evaluating the activity of H2S synthetase. [ABSTRACT FROM AUTHOR]

A one-pot approach has been developed to synthesize copper nanocluster (Cu NC) aggregates from copper nitrate and mercaptobenzoic acid (MBA). Cu NCs prepared separately in the three isomers of MBA exhibit different physical and optical properties. [ABSTRACT FROM AUTHOR]

In this study, we designed a system of integrating gold nanoparticles and cysteamine to detect Cu2+ based on a colorimetric strategy. The quantified limit of detection towards Cu2+ is 0.4 µM, which is ∼50 times lower than the maximum contamination level (∼20 µM) in drinking water permitted by US environmental protection agency. The practicality of this system was further validated by detecting Cu2+ in different water samples. [ABSTRACT FROM AUTHOR]

Cyanide (CN−) is a highly toxic anion to human beings, exploring efficient probes for sensitive and selective detection of it is very important. In this study, we explore a simple one-pot reaction to synthesize polyethyleneimine (PEI) solubilized Au(I)-MUA (11-mercaptoundecanoic acid) complexes under mild condition. The as prepared Au(I)-MUA complexes exhibit strong red photoluminescence (PL) and can act as sensitive and selective CN− optical sensor in aqueous media based on the chemical reaction between CN− and gold atom that quench the fluorescence, and the limit of detection is 10 nM, which is ∼270 times lower than the maximum contamination level (2.7 μM) in drinking water permitted by WHO. Additionally, real water sample from a local lake is tested with these optical sensors, and the PL variation caused by 0.1 μ CN− can be observed. [ABSTRACT FROM AUTHOR]