Strategies in liquid-phase chemiluminescence and their applications in bioassay

Efficient Discrimination of Hazardous Organophosphate Flame Retardants via Cataluminescence-Based Multidimensional Ratiometric Sensing

Emerging contaminants have recently evolved into a severe worldwide environmental issue. Organophosphate flame retardants (OPFRs) with neurotoxicity, genotoxicity, and reproductive and developmental toxicity are a class of notorious emerging contaminants that cause great concern. The development of high-efficiency and portable sensors for rapid online monitoring of OPFRs has become the primary demand for the exploration of the environmental migration and transformation of OPFRs. In this work, interestingly, the cataluminescence (CTL) phenomenon of OPFRs is first observed, and an ingenious multidimensional ratiometric CTL sensing strategy is developed for the recognition of multiple OPFRs. Three characteristic ratios are extracted from the multipeak CTL spectral curves based on energy transfer of single Tb/Eu-modified MgO sensing material, and thus a novel three-dimensional (3D) code recognition could be mapped out. This obtained 3D coordinate is found to be a unique characteristic for a given OPFR, just like an exclusive person's ID number, which can successfully discriminate and detect 10 kinds of OPFR vapors, including homologous series and isomers. More importantly, CTL mechanism investigations for OPFRs demonstrate that OPFRs undergo a series of chemical reaction processes, e.g., oxidative pyrolysis and hydroxylation, and different high-energy excited intermediates are generated, which trigger discrepant energy-transfer efficiency toward rare earth ions, leading to multipeak spectral profiles. Briefly, this proposed CTL analytical platform for OPFRs recognition initiates a new sensing principle for the efficient identification of emerging contaminants and shows significant prospects on rapid on-site detection.

Recent Advances in Nanomaterial-Based Chemiluminescence Probes for Biosensing and Imaging of Reactive Oxygen Species

Reactive oxygen species (ROS) play important roles in organisms and are closely related to various physiological and pathological processes. Due to the short lifetime and easy transformation of ROS, the determination of ROS content in biosystem has always been a challenging task. Chemiluminescence (CL) analysis has been widely used in the detection of ROS due to its advantages of high sensitivity, good selectivity and no background signal, among which nanomaterial-related CL probes are rapidly developing. In this review, the roles of nanomaterials in CL systems are summarized, mainly including their roles as catalysts, emitters, and carriers. The nanomaterial-based CL probes for biosensing and bioimaging of ROS developed in the past five years are reviewed. We expect that this review will provide guidance for the design and development of nanomaterial-based CL probes and facilitate the wider application of CL analysis in ROS sensing and imaging in biological systems.

A chemiluminescence biosensor based on the peroxidase-like property of molybdenum disulfide/zirconium metal-organic framework nanocomposite for diazinon monitoring

BACKGROUND

Organophosphorus pesticides are widely used in agriculture owing to their high effectiveness as insecticides. Among these, diazinon is a common environmental contaminant that acts as an acetylcholinesterase (AChE) enzyme inhibitor. As the current methods are too expensive and time-consuming for routine analysis of diazinon, its trace monitoring by rapid and sensitive methods is critical to protect the environment and human health.

RESULTS

A biosensor was introduced for the indirect detection of diazinon using a molybdenum disulfide/zirconium metal-organic framework (MoS₂@MIP-202(Zr)) nanocomposite. The probe is based on the peroxidase mimic of the prepared nanocomposite on NaHCO₃-H₂O₂ chemiluminescence system as well as the inhibitory effect of diazinon on the enzymatic activity of AChE. The chemiluminescence signal is gradually decreased with an increase in diazinon concentration, and there is a linear relationship between the analytical signal and diazinon concentration. Under the optimum conditions, the calibration plot is linear in the concentration range of 0.5-300.0 nmol L^-1. The limit of detection and quantification limit of the method are 0.12 and 0.40 nmol L^-1, respectively. The inter-day and intra-day relative standard deviations (% RSD n = 5, diazinon concentration; 100 nmol L^-1) are 3.66 and 1.35%, respectively. The method was used for diazinon detection in real water samples, and the high relative recovery values for the spiked samples along with satisfactory results of a certified reference material analysis confirmed that the method is accurate and free from the matrix effect.

SIGNIFICANCE AND NOVELTY

A nano-probe based on the peroxidase-like property of MoS₂@MIP-202(Zr) nanocomposite was developed for the first time for indirect detection of residue levels of diazinon in water samples. The high stability of the nanocomposite makes it a good alternative for natural peroxidase enzymes such as horseradish peroxidase with low stability.

Laccase-luminol chemiluminescence system: an investigation of substrate inhibition

Chemiluminescence (CL) reactions are widely used for the detection and quantification of many types of analytes. Laccase has previously been proposed in CL reactions; however, its light emission behaviour has not been characterized. This study was conducted to characterize the laccase-luminol system, determine its kinetic parameters, and analyze the effects of protein and OH- concentration on the CL signal. Laccase from Coriolopsis gallica was combined with different concentrations of luminol (125 nM to 4 mM), and the enzyme kinetics were evaluated using diverse kinetic models. The laccase-luminol system was able to produce CL without an intermediate molecule, but it exhibited substrate-inhibition behaviour. A two-site random model was used and suggested that when the first luminol molecule was bound to the active site, laccase affinity for the second luminol molecule was increased. This inhibition effect could be avoided using a low luminol concentration. At 5 μM luminol concentration, 1 mg/ml (0.13 U) laccase is needed to achieve nearly 90% of the maximum CL signal, suggesting that the available luminol could not bind to all active sites. Furthermore, the concentration of NaOH negatively affected the CL signal. The laccase-luminol system represents an alternative to existing CL systems, with potential uses in molecular detection and quantification.

Flower-like Gold Nanoparticles for In Situ Tailoring Luminescent Molecules for Synergistic Enhanced Chemiluminescence

In recent years, gold nanoparticles (AuNPs) have attracted much attention due to their ease of surface modification, excellent biocompatibility, and extraordinary optoelectronic and catalytic activities. Herein, based on a AuNP-catalyzed reaction, a strategy for tailoring luminescent molecules in situ is proposed to trigger an ultrastrong chemiluminescence (CL). In the strategy, flower-like AuNPs are prepared using CL molecular probes (Probe-OH for NaClO/ONOO^-) via one-pot synthesis and subsequently act as a tailor for Probe-OH to generate novel CL molecules, allowing a synergistic CL enhancement about 4 times that of initial Probe-OH. Furthermore, by modification with poly(vinylpyrrolidone) (PVP) on the surface, the CL signals (only for NaClO) are amplified by 100 times based on an intermolecular chemically initiated electron exchange luminescence (CIEEL) mechanism. Given the improved sensitivity and selectivity over Probe-OH, the thus-formed CIEEL nanoplatform (PVP-Au) is successfully developed for detecting NaClO in a wide range of 2.5-100 μM, and the detection limit is 10.68 nM. This work provides unprecedented perspectives for expanding this facile and effective strategy for CL amplification based on AuNP catalysis.

Europium functionalized black phosphorus quantum dots as a CRET platform for synergistically enhanced chemiluminescence

In this work, we synthesize stable europium ion modified black phosphorus quantum dots (Eu-BPQDs) using a microwave irradiation technique, which can react with organic amines exhibiting unique chemiluminescence (CL). The mechanism of the Eu-BPQDs/organic amines CL system accounting for the efficient CRET is induced by the chelation of organic amines with the surface functionalized europium.

Chemiluminescence resonance energy transfer determination of uric acid with fluorescent covalent organic framework as energy acceptor

A simple and feasible strategy was developed for the preparation of fluorescent covalent organic frameworks (COFs) TpPa-1@FL. The TpPa-1-1@FL was prepared via a self-assembly strategy by soaking non-fluorescent COFs TpPa-1 into strong fluorescent fluorescein (FL) solution. A chemiluminescence resonance energy transfer (CRET) system was constructed by the combination strong fluorescent TpPa-1@FL with TCPO-hydrogen peroxide (H₂O₂) reaction. The chemiluminescence (CL) signal of the system was further improved by the addition of bovine serum albumin (BSA). The CRET system can determine H₂O₂ with a linear range response from 5.0 µmol/L to 20.0 mmol/L and a detection limit of 1.1 µmol/L. The CRET system was further exploited for indirect detection of uric acid with coupling of uricase. A good linear relationship was obtained for uric acid in the 10.0-400.0 µmol/L concentration range with a detection limit of 3.8 µmol/L. The practicability of this method was assessed by the determination of uric acid in real samples of human serum and urine.

Recent advances and perspectives of enzyme-based optical biosensing for organophosphorus pesticides detection

The overuse or abuse of organophosphorus pesticides (OPs) can bring about severe contamination problems in foodstuff and the environment, which will seriously threaten human health and the ecosystem's cycle. Hence, it is in high demand to establish sensitive, portable, specific, and cost-effective methods for monitoring OPs to control food safety, protect the ecosystem, and prevent disease. The optical biosensor with enzyme as bio-recognition elements has been an effective alternative for OPs detection. Herein, we firstly introduce various enzymes, sensing mechanisms, advantages and disadvantages used as bio-recognition elements in optical sensing for OPs detection. Then, we review various optical biosensing strategies based on enzymes as recognition elements that were ingeniously designed and successfully utilized for OPs detection, with a particular emphasis on photoluminescence (PL), chemiluminescence (CL), electrochemiluminescence (ECL), and colorimetric (CM) biosensing strategies. We not only highlight the state-of-art developments and the construction strategies of the enzyme-based optical biosensing method but also summarize the existing deficiencies, current challenges, and the future perspectives of OPs detection.

Rapid chiral analysis based on liquid-phase cyclic chemiluminescence

Rapid chiral analysis has become one of the important aspects of academic and industrial research. Here we describe a new strategy based on liquid-phase cyclic chemiluminescence (CCL) for rapid resolution of enantiomers and determination of enantiomeric excess (ee). A single CCL measurement can acquire multistage signals that provide a unique way to examine the intermolecular interactions between chiral hosts and chiral guests, because the lifetime (τ) of the multistage signals is a concentration-independent and distinguishable constant for a given chiral host-guest system. According to the τ values, CCL allows discrimination between a wide range of enantiomeric pairs including chiral alcohols, amines and acids by using only one chiral host. Even the chiral systems hardly distinguished by nuclear magnetic resonance and fluorescence methods can be distinguished easily by CCL. Additionally, the τ value of a mixture of two enantiomers is equal to the weighted average of each enantiomer, which can be used for the direct determination of ee without the need to separate the chiral mixture and create calibration curves. This is extremely crucial for the cases without readily available enantiomerically pure samples. This strategy was successfully applied to monitoring of the Walden inversion reaction and analysis of chiral drugs. The results were in good agreement with those obtained by high-performance liquid chromatography, indicating the utility of CCL for routine quick ee analysis. Mechanism study revealed that the τ value is possibly related to the activity of the chiral substance to catalyze a luminol-H2O2 reaction. Our research provides an unprecedented and general protocol for chirality differentiation and ee determination, which is anticipated to be a useful technology that will find wide application in chirality-related fields, particularly in asymmetric synthesis and the pharmaceutical industry.

Advances in chemiluminescence and electrogenerated chemiluminescence based on silicon nanomaterials

Since 1950, when chemiluminescence (CL) of siloxane upon treatment with strong oxidants was discovered by Kurtz, many silicon-based nanomaterials with different elements, specific molecules, shapes and sizes have been developed as light emitters, energy acceptors, and catalyzers to provide valuable CL and electrogenerated CL (ECL) detection platforms in analytical chemistry fields. This review mainly focuses on the recent development of their mechanisms and sensing methodologies for small molecules, free radicals, ion, enzyme, protein, DNA, cancer cells, and metabolites based on specific reactions such as aptamer sensing and enzymatic reaction. Additionally, the future trend is discussed.

An assay for Staphylococcus aureus based on a self-catalytic ampicillin–metal (Fe3+)-organic gels–H2O2 chemiluminescence system with near-zero background noise

A self-catalytic ampicillin–metal (Fe³⁺)-organic gels (AMP–MOGs (Fe))–H₂O₂ CL system, which is not influenced by transition metal ions, was studied.

Synergistic chemiluminescence nanoprobe: Au clusters-Cu2+-induced chemiexcitation of cyclic peroxides and resonance energy transfer

An interesting chemiluminescence (CL) phenomenon of cyclic peroxides originating from tetrahydrofuran hydrogen peroxide (THF-HPO) in the presence of BSA-stabilized Au NCs (Au@BSA NCs) was found for the first time.

Luminescent metal organic frameworks-based chemiluminescence resonance energy transfer platform for turn-on detection of fluoride ion

A luminescent metal organic frameworks (MOFs)-based chemiluminescence resonance energy transfer (CRET) platform was constructed for turn-on detection of fluoride ion. A hybrid MOFs was prepared by encapsulating strong fluorescence 2',7'-dichlorofluorescein (DCF) into the frames of NH₂-MIL-101(Al) MOFs, which led to a significant suppression of fluorescence signal of DCF. In the presence of fluoride ion, it destroyed the structure of the hybrid MOFs and released DCF molecules from the frames due to the formation of more stable aluminum hexafluoride complex ions [AlF₆^3-] between fluoride ion and aluminum ion. The released DCF molecules accepted the energy originating from the chemical reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) with hydrogen peroxide (H₂O₂), producing a strong chemiluminescence (CL) emission. The CL signal was strong dependent on the concentration of fluoride ion presented and showed a linear response in the range of 0.5-80.0 μmol L^-1 (9.5 μg L^-1-1.52 mg L^-1). The detection limit was 0.05 μmol L^-1 (about 0.95 μg L^-1) fluoride ion and the relative standard deviations was 2.3% for 40.0 μmol L^-1 fluoride ion solution (n = 11). This MOFs-based CRET method was successfully applied to the determination of fluoride ion in drinking water samples, demonstrating its potential application in analysis of real samples.

Chemiluminescence of Oleic Acid Capped Black Phosphorus Quantum Dots for Highly Selective Detection of Sulfite in PM2.5

Quantum dots (QDs), especially metal-free QDs with their unique optoelectronic properties, environmental friendliness, and excellent biocompatibility, have opened a new avenue to explore novel chemiluminescence (CL) systems for analytical applications. However, the unknown CL properties, relatively weak emission, and instability of some of them in water (e.g., black phosphorus QDs) often seriously hinder their further practical applications. Chemical modification trends have offered new properties for materials and have been proved to be desirable ways to establish sensing platforms with improved sensitivity and stability. Herein, oleic acid capped black phosphorus QDs (OA-BP QDs) with improved stability and optical properties were successfully synthesized. More importantly, an extraordinary CL emission when OA-BP QDs reacted with SO₃^2- was first observed. In the CL process, OA-BP QDs acted as the catalyst to trigger singlet oxygen (¹O₂) generation in NaHSO₃, and then a chemiluminescence resonance energy transfer (CRET) between (¹O₂)₂* (¹O₂ dimeric aggregate) and OA-BP QDs was produced. On this basis, a new CL system for directly monitoring SO₃^2- in airborne fine particulate matter (PM_2.5) was fabricated. The study opens attractive perspectives of modified metal-free QDs for the practice of CL in monitoring the chemical species in PM_2.5.

A Highly Efficient Chemiluminescence System Based on an Enhancing Effect of Ag Nanoclusters/Graphene Quantum Dots Mixture for Ultrasensitive Detection of Rabeprazole

Herein, an efficient chemiluminescence (CL) reaction with a high emission intensity is reported based on a synergistic improving effect of silver nanoclusters (AgNCs) and graphene quantum dots (GQDs). First, the syntheses of AgNCs and GQDs were simply performed by the chemical reducing of AgNO₃ and a thermal treatment of glucose, respectively. After the characterization steps, the beneficial behavior of the prepared nanomaterial was investigated in CL systems. The oxidation reaction of KMnO₄-rhodamine B produced weak CL emission. However, the presence of AgNCs and GQDs led to a synergetic enhancing effect, and thus higher emission was obtained. A possible mechanism was investigated for this effect using absorption and fluorescence experiments. Furthermore, rabeprazole showed a relatively selective enhancing impact on the CL emission. The CL intensity was linearly increased in the rabeprazole concentration range of 4 - 133 ng mL^-1 with a detection limit (3S_b/m) of 1.1 ng mL^-1. The developed CL method was utilized for the measurement of Rbp in biological samples with acceptable precision and accuracy.

CdSe quantum dots-sensitized chemiluminescence system and quenching effect of gold nanoclusters for cyanide detection

An efficient chemiluminescence resonance energy transfer (CRET) induced chemiluminescence (CL) system was developed for the sensitive determination of cyanide ion (CN^-) in environmental and biological samples. The selected CL reaction was hydrogen peroxide (H₂O₂)-bicarbonate (HCO₃^-) system with an ultra-weak emission at about 470 nm. It was found that glutathione-stabilized CdSe quantum dots (CdSe QDs) superbly increase the obtained CL intensity. The high performance CRET between the CL emitters and CdSe QDs with a broad absorption was mainly responsible for the observed improving effect. The absorption spectrum of QDs completely overlaps with the CL emission wavelength of H₂O₂-HCO₃^- system. Besides, CdSe QDs could also catalyze the CL reaction of H₂O₂-HCO₃^-, efficiently. On the other hand, it was observed that the gold nanoclusters (Au NCs) could prohibit the CRET system and turn off the CL emission. This diminishing effect can be useful for the analytical application. Herein, it was successfully exploited for the selective recognition of CN^-, using its leaching effect on Au NCs. After efficient dissolution of NCs, the CRET to CdSe QDs restored and the CL emission was again turned on. This strategy resulted in a high sensitive and reliable measurement of CN^- in the concentration range of 2-225 nM, with a detection limit of 0.46 nM.

A Chemiluminescent Method for the Detection of H₂O₂ and Glucose Based on Intrinsic Peroxidase-Like Activity of WS₂ Quantum Dots

Currently, researchers are looking for nanomaterials with peroxidase-like activity to replace natural peroxidase enzymes. For this purpose, WS₂ quantum dots (WS₂ QDs) were synthesized via a solvothermal method, which improved the mimetic behavior. The resulting WS₂ QDs with a size of 1⁻1.5 nm had a high fluorescence emission, dependent on the excitation wavelength. WS₂ QDs with uniform morphology showed a high catalytic effect in destroying H₂O₂. The peroxidase-like activity of synthesized nanostructures was studied in H₂O₂ chemical and electrochemical reduction systems. The mimetic effect of WS₂ QDs was also shown in an H₂O₂⁻rhodamine B (RB) chemiluminescence system. For this aim, a stopped-flow chemiluminescence (CL) detection system was applied. Also, in order to confirm the peroxidase-like effect of quantum dots, colorimetry and electrochemical techniques were used. In the enzymatic reaction of glucose, H₂O₂ is one of the products which can be determined. Under optimum conditions, H₂O₂ can be detected in the concentration range of 0⁻1000 nmol·L-1, with a detection limit of 2.4 nmol·L-1. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.01⁻30 nmol·L-1, with a limit of detection (3S) of 4.2 nmol·L-1.

Ultrasensitive chemiluminescence assay for cimetidine detection based on the synergistic improving effect of Au nanoclusters and graphene quantum dots

A novel and sensitive chemiluminescence (CL) procedure based on the synergetic catalytic effects of gold nanoclusters (Au NCs) and graphene quantum dots (GQDs) was developed for the reliable measurement of cimetidine (CM). The initial experiments showed that the KMnO₄ -based oxidation of alkaline rhodamine B (RhoB) generated a very weak CL emission, which was intensively enhanced in the simultaneous presence of Au NCs and GQDs. CL intermediates can be adsorbed and gathered on the surface of Au NCs, becoming more stable. GQDs participate in the energy transferring processes and facilitate them. These improving effects were simultaneously obtained by adding both Au NCs and GQDs into the RhoB-KMnO₄ reaction. Consequently, the increasing effect of the Au NCs/GQDs mixture was more than that of pure Au NCs or GQDs, and a new nano-assisted powerful CL system was achieved. Furthermore, a marked quenching in the emission of the introduced CL system was observed in the presence of CM, so the system was examined to design a sensitive sensor for CM. After optimization of influencing parameters, the linear lessening in CL emission intensity of KMnO₄ -RhoB-Au NCs/GQDs was verified for CM concentrations in the range 0.8-200 ng ml^-1 . The limit of detection (3S_b /m) was 0.3 ng ml^-1 . Despite being a simple CL method, good sensitivity was obtained for CM detection with reliable results for CM determination in human urine samples.

Determination of ferric ion via its effect on the enhancement of the chemiluminescece of the permanganate-sulfite system by nitrogen-doped graphene quantum dots

Nitrogen-doped graphene quantum dots (NGQDs) are shown to strongly enhance the integrated chemiluminescence (CL) of the permanganate-sulfite system. The mechanism of enhancement was investigated, and the catalytic effect of the NGQDs was proven. In contrast to other carbon-based nanomaterials, the enhancement by NGQDs is independent of particle size and surface. However, the pyridinic nitrogen on the surface of the NGQDs facilitates the transformation of dissolved oxygen into H₂O₂ and the generation of hydroxyl radicals. This induces the increase of CL intensity. However, in the presence of Fe³⁺, the nitrogen functions and phenol groups on the surface of the NGQDs will chelate it, and the CL signal is decreased as a result. This effect was used to design an assay for Fe³⁺ that has a wide response range (1 × 10^-8 - 1 × 10^-6 M) and a 4 nM detection limit. The method was successfully applied to the determination of Fe³⁺ in spiked real water samples. Graphical abstract Nitrogen-doped graphene quantum dots (NGQDs) are demonstrated to strongly enhance the integrated chemiluminescence (CL) of the permanganate-sulfite system. The pyridinic N-atoms in NGQDs facilitate the transformation from dissolved oxygen into H₂O₂ and the generation of •OH radicals. This leads to the highly enhanced CL of the system. In the presence of Fe³⁺, which will be chelated by the nitrogen functions and phenol groups on the surface of the NGQDs, the CL signal is decreased.

Improved peroxidase mimetic activity of a mixture of WS2 nanosheets and silver nanoclusters for chemiluminescent quantification of H2O2 and glucose

It is reported that a mixture of WS₂ nanosheets (WS₂ NS) and silver nanoclusters (AgNCs) displays strongly enhanced peroxidase-mimicking activity. The catalytic effect of the mixture was studied by colorimetry, fluorometry, chemiluminescence (CL) and electrochemistry. The effect is interpreted in terms of a difference between the Fermi energy level of the two nanomaterials. This leads to the formation of charge separation regions which act as active sites for enzyme mimetic interaction with the substrates. The mixture of WS₂ NS and AgNCs was exploited for the non-enzymatic determination of H₂O₂ and glucose. A stopped-flow method was applied as a sensitive CL detection system using the bicarbonate-H₂O₂ reaction. The mixture has a powerful peroxidase mimicking activity on the bicarbonate-H₂O₂ CL reaction, and this effect is much larger than that of any single constituent. In addition, the CL emission is improved several times by using the stopped-flow technique. Under optimum condition, H₂O₂ can be determined in the 2.5-1500 nM concentration range. Moreover, glucose levels in human serum can be quantified via glucose oxidase based oxidation which leads to the generation of H₂O₂. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.03-20 μM, with a limit of detection (3S) of 13 nM. Graphical abstract An enhanced peroxidase-like catalytic activity for WS₂ nanosheets (WS₂ NS) was revealed in the presence of silver nanoclusters (AgNCs), and was exploited for the non-enzymatic determination of H₂O₂, and of glucose (via glucose oxidase; GOx) using a stopped-flow CL method.

Chemiluminescence of black phosphorus quantum dots induced by hypochlorite and peroxide

For the first time, black phosphorus quantum dots (BP QDs) were found to show chemiluminescence (CL) properties in the presence of hydrogen peroxide (H₂O₂) and hypochlorite (ClO⁻).

Nanomaterials for the optical detection of fluoride

Overexposure to fluoride ions (F^-) causes serious diseases in human beings. Extensive efforts have been made to develop sensitive and selective approaches for F^- detection and a variety of F^- sensors have been constructed recently. The burgeoning nanotechnology has provided novel materials for F^- analysis due to the extraordinary properties of nanomaterials. In this review, we present the recent advances in different nanomaterials-based approaches for the optical F^- detection via colorimetric, fluorescent and chemiluminescent responses. The materials include gold nanomaterials, CeO₂ nanoparticles, semiconductor quantum dots, carbon quantum dots, metal-organic frameworks, upconversion nanoparticles, micellar nanoparticles, polymer dots, SiO₂ nanoparticles and graphene oxide. The recent trends and challenges in the optical detection of F^- with various nanomaterials are also discussed.

Determination of dihydralazine based on chemiluminescence resonance energy transfer of hollow carbon nanodots

The famous weak chemiluminescence (CL) system of potassium permanganate and sodium bisulfite (KMnO₄-HSO₃^-) was enhanced by the hollow fluorescent carbon nanodots (HCNs). The investigation of mechanism revealed that the enhanced CL was induced by the excited-state HCNs (HCNs^⁎), which could be produced from the electron-transfer annihilation of positively charged HCNs (HCNs⁺) and negatively charged HCNs (HCNs^-) as well as by CL resonance energy transfer (CRET) from excited SO₂ (SO₂^⁎)/¹O₂ to HCNs. The dihydralazine sulfate (DHZS) had a diminishing effect on the CL of HCNs-KMnO₄-HSO₃^- system due to the competitive consumption of O₂^-. Under the optimal conditions, the reduced CL signal with the concentration of DHZS was linear in the range of 1.0×10^-7-7.0×10^-5mol/L with a detection limit of 3.0×10^-8mol/L. The relative standard deviation for seven repeated determination of 5.0×10^-6mol/L DHZS was 2.1%. The established method was applied to the determination of DHZS in pharmaceutical preparations, human urine and plasma samples with good precision and accuracy.

Nanotechnology-Enhanced No-Wash Biosensors for in Vitro Diagnostics of Cancer

In vitro biosensors have been an integral component for early diagnosis of cancer in the clinic. Among them, no-wash biosensors, which only depend on the simple mixing of the signal generating probes and the sample solution without additional washing and separation steps, have been found to be particularly attractive. The outstanding advantages of facile, convenient, and rapid response of no-wash biosensors are especially suitable for point-of-care testing (POCT). One fast-growing field of no-wash biosensor design involves the usage of nanomaterials as signal amplification carriers or direct signal generating elements. The analytical capacity of no-wash biosensors with respect to sensitivity or limit of detection, specificity, stability, and multiplexing detection capacity is largely improved because of their large surface area, excellent optical, electrical, catalytic, and magnetic properties. This review provides a comprehensive overview of various nanomaterial-enhanced no-wash biosensing technologies and focuses on the analysis of the underlying mechanism of these technologies applied for the early detection of cancer biomarkers ranging from small molecules to proteins, and even whole cancerous cells. Representative examples are selected to demonstrate the proof-of-concept with promising applications for in vitro diagnostics of cancer. Finally, a brief discussion of common unresolved issues and a perspective outlook on the field are provided.

Ultra-weak chemiluminescence enhanced by facilely synthesized nitrogen-rich quantum dots through chemiluminescence resonance energy transfer and electron hole injection

In this study, a novel nitrogen-rich dots were easily synthesized with high percentage of nitrogen and exhibited unique CL property.