Nanomaterial-enhanced chemiluminescence reactions and their applications

Chemiluminescence of silver and nitrogen doped carbon dots induced by potassium ferricyanide/hydrogen peroxide and its analytical application

In this study, carbon dots doped with silver and nitrogen (Ag,N-CDs) were synthesized and their application in chemiluminescence (CL) was investigated using the potassium ferricyanide/hydrogen peroxide (K3Fe(CN)6/H2O2) reaction. Theoretical calculations reveal that Ag doping facilitates a lower excitation energy. The experimental conditions influencing the CL reaction were examined and optimized. The resulting Ag,N-CDs-based CL method demonstrated impressive capabilities in detection of Cu(II) within a linear calibration range of 40.0 nM-8.0 μM, with a commendable detection limit of 3.1 nM. In extensive validation experiments, recoveries and relative standard deviations for water, plasma, and tea samples consistently fell within the range of 97.0-103.0 % and 1.03-4.19 %, respectively. These outcomes underscore that the CL method based Ag,N-CDs is an excellent tool for the detection of Cu(II).

Domino-like turn-on chemiluminescence amplification: Opening a gateway through proximal-imidazole species formation and metal-ligand complexation

Due to their extremely low background signal and high sensitivity, the chemiluminescence (CL) probes have received a great attention in various chemical and biological applications. However, the lack of selectivity is still a challenging task. As an innovative topic of research, in this work we developed a domino-like turn-on CL reaction through proximal-imidazole species for the first time. The oxidation reaction of N-(2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide (1) by hydrogen peroxide found to promoted by a domino-like reaction between proximal imidazole species and the Co2+-1 complex formation which accompanied by a dramatically turn-on emission. In the way of explaining the possible mechanism, the application of density functional theory (DFT) studies revealed that there are three possible pathways for the reactions between precursor 1 and HOO- in the presence of imidazole to produce the oxidized isomers. The strongest interaction found to occur in pathway 3, in which the sulfur atom was oxidized, while there was some repulsion between HOO- and 1, due to the effects of two different charges in pathways 1 and 2. To confirm tits applicability, the CL system was successfully applied to highly selective quantification of vitamin B12 in some real samples. The linear dynamic range was achieved from 0.08 to 34 ng mL-1 and the detection limit was evaluated as 0.028 ng mL-1. This new method introduced fluorescence selectivity and CL sensitivity in single technique. It was finally anticipated that the CL amplification through proximal-imidazole species possesses a great potential on tuning various color-emissions based on different metal-ligand complex formations studied.

The outputs of molecular sensors detectable by human senses

Molecular sensors respond to the presence of biological analytes by producing signals that are either directly perceivable by human sensory systems or converted into electric signals, which require electronic devices for communicating the signals to humans. Here, we review the outputs of molecular sensors detectable directly by human senses. According to the literature, sensors with visual outputs dominate. Undeservedly unnoticed, sensors that release gases might be particularly useful since the gas output can be detected with the several human senses in a quantifiable format. Relatively new sensors with tactile outputs can be accessed by visually impaired people. Molecular sensors communicating their outputs directly to human senses bypassing electronic devices may contribute to the development of point-of-care testing technologies, as well as providing the direct communication of molecular nanorobots with humans.

Self-Illuminating Copper-Luminol Coordination Polymers for Bioluminescence Imaging of Oxidative Damage

Timely detection of reactive oxygen species (ROS) accumulated during inflammation is essential for an early disease diagnosis. Compared to fluorescence probes with limited sensitivity and accuracy, chemiluminescence (CL) imaging offers the potential for highly sensitive molecular visualization of ROS by minimizing background interferences. However, the development of bright and easily manufacturable CL probes for ROS imaging remains challenging. In this study, a novel chemiluminescent nanoprobe named Cu-Lum@NPs for ROS imaging in inflammation was synthesized by using a one-step solvothermal method. The Cu-Lum@NPs, which are composed of coordination polymers containing copper ions and luminol (Lum), demonstrate intrinsic peroxidase-like activity that relies on Cu(I) as the catalytic active center to initiate the Fenton reaction. This catalytic process facilitates the decomposition of hydrogen peroxide (H2O2) into hydroxyl radicals (•OH) and superoxide anion radicals (O2•-), leading to the oxidation of Lum and inducing strong luminescence. Cu-Lum@NPs, displaying nanozyme characteristics, were observed to accelerate and enhance the ROS-responsive luminescence (10-1600-fold in solution and over 100-fold in neutrophils) and notably extend persistent luminescence. The Cu-Lum@NPs allowed for CL imaging of endogenous ROS in living cells and animals with an outstanding signal-to-noise ratio exceeding 96 and facilitated oxidative damage luminescence imaging for tissue-specific detection. The study presents Cu-Lum@NPs, a highly sensitive and easily manufacturable chemiluminescent nanoprobe for ROS imaging both in vitro and in vivo, exhibiting enhanced luminescence and prolonged persistence for ROS-related disease detection.

Wireless Gold/Boron-Nitrogen-Codoped Graphene-Based Antenna Immunosensor for the Rapid Detection of Neuron-Specific Enolase

Tumor-marker immunosensors for rapid on-site detection have not yet been developed because of immunoreaction bottlenecks, such as shortening the reaction time and facilitating incubation. In this study, a gold-boron-nitrogen-codoped graphene (Au-BNG)-based immunosensor antenna was constructed for the rapid detection of neuron-specific enolase (NSE). A Au-BNG radiation electrode with dual functions of antibody protein fixation and signal transmission was developed for the first time. A radiation sample cell was constructed by embedding a radiation electrode into the groove of a poly(dimethylsiloxane) dielectric substrate. The constructed sense antenna achieves accurate detection of NSE with a range from 50 fg mL-1 to 40,000 pg mL-1 and a limit of detection of 10.99 fg mL-1, demonstrating excellent selectivity, stability, and reliability. The tumor-marker detection meter can provide NSE detection results as rapidly as within 2 min by using the new strategy of the microwave self-incubation of tumor markers. This antenna immunosensor is suitable for rapid detection in outpatient clinics and can be developed into household tumor-marker detectors, which would be significant in the early detection, long-term monitoring, and efficacy evaluation of tumors.

Micelle-mediated chemiluminescence of 6-aza-2-thiothymine-protected gold nanoclusters for carbazochrome sodium sulfonate detection

Chemiluminescence (CL) intensity of luminol-H2O2 system was dramatically enhanced by cetyltrimethylammonium bromide (CTAB) micelle-mediated 6-aza-2-thiothymine-protected gold nanoclusters (ATT-AuNCs). It is proved that spherical micelles of CTAB in aqueous solution improved the dispersity of ATT-AuNCs, thus enhancing their catalytic activity, which brought in the increased CL intensity of luminol-H2O2 system. Carbazochrome sodium sulfonate (CSS) with a hemostatic containing tetrahydroindole structure broke the spherical micelles and notably quenched the CL intensity of luminol-H2O2-CTAB-ATT AuNCs system. Based on these results, a simple, fast, and sensitive CL method has been developed for the detection of CSS with a linear range of 0.25-25 μM and a detection limit of 0.11 μM. The method has also been successfully applied to the determination of CSS in serum with satisfied recoveries in the range of 89.6 % to 103.7 %. This study not only provides an effective approach for CSS detection but also paves the way for AuNCs-based CL applications.

Nanoscale Luminescence Imaging/Detection of Single Particles: State-of-the-Art and Future Prospects

Single-particle-level measurements, during the reaction, avoid averaging effects that are inherent limitations of conventional ensemble strategies. It allows revealing structure-activity relationships beyond averaged properties by considering crucial particle-selective descriptors including structure/morphology dynamics, intrinsic heterogeneity, and dynamic fluctuations in reactivity (kinetics, mechanisms). In recent years, numerous luminescence (optical) techniques such as chemiluminescence (CL), electrochemiluminescence (ECL), and fluorescence (FL) microscopies have been emerging as dominant tools to achieve such measurements, owing to their diversified spectroscopy principles, noninvasive nature, higher sensitivity, and sufficient spatiotemporal resolution. Correspondingly, state-of-the-art methodologies and tools are being used for probing (real-time, operando, in situ) diverse applications of single particles in sensing, medicine, and catalysis. Herein, we provide a concise and comprehensive perspective on luminescence-based detection and imaging of single particles by putting special emphasis on their basic principles, mechanistic pathways, advances, challenges, and key applications. This Perspective focuses on the development of emission intensities and imaging based individual particle detection. Moreover, several key examples in the areas of sensing, motion, catalysis, energy, materials, and emerging trends in related areas are documented. We finally conclude with the opportunities and remaining challenges to stimulate further developments in this field.

Quantification strategy of absolute chemiluminescence efficiency for systems of luminol with hydrogen peroxide

An important feature to be determined in mechanistic studies on chemiluminescence (CL) is its quantum efficiency, which can give significant chemical reaction information on the influence of the reactant structures and reaction conditions. However, most of the previous quantitative measurements of luminescence and quantum efficiencies are complex and incomplete. To overcome the inconvenience and underestimated quantum efficiency in each measurement, we report a simple and highly effective strategy to determine the absolute CL quantum efficiencies for three systems of luminol with hydrogen peroxide by means of a spectrometer along with an integrating sphere. The integrating sphere facilitated collection of all the emitted light and then transferred it to the spectrometer via an optical fiber proportionally. The CL quantum efficiency was determined by taking the ratio of total photons generated in the reaction system to the number of the limiting reactant molecules consumed. Absolute CL efficiencies of three luminol-H2O2 reaction systems with varied reactant concentrations or coreactants were found to be 37 %, 7.0 % and 6.6 % in a time course, which are much higher than those previously reported values of 1.0-1.3 %. Due to our complete photon collection design, a higher absolute CL efficiency can be realized. Furthermore, spooling CL spectra also provided a powerful visualization tool to observe the real-time CL evolution and devolution, allowing the study on kinetics of CL reaction systems. The above investigations are anticipated to promote further development of CL methodologies and their applications.

Nanomaterials-based aptasensors: An efficient detection tool for heavy-metal and metalloid ions in environmental and biological samples

In light of potential risks of heavy metal exposure, diverse aptasensors have been developed through the combination of aptamers with nanomaterials for the timely and efficient detection of metals in environmental and biological matrices. Aptamer-based sensors can benefit from multiple merits such as heightened sensitivity, facile production, uncomplicated operation, exceptional specificity, enhanced stability, low immunogenicity, and cost-effectiveness. This review highlights the detection capabilities of nanomaterial-based aptasensors for heavy-metal and metalloid ions based on their performance in terms of the basic quality assurance parameters (e.g., limit of detection, linear dynamic range, and response time). Out of covered studies, dendrimer/CdTe@CdS QDs-based ECL aptasensor was found as the most sensitive option with an LOD of 2.0 aM (atto-molar: 10-18 M) detection for Hg2+. The existing challenges in the nanomaterial-based aptasensors and their scientific solutions are also discussed.

Impact of nanotechnology on progress of flow methods in chemical analysis: A review

In evolution of instrumentation for analytical chemistry as crucial technological breakthroughs should be considered a common introduction of electronics with all its progress in integration, and then microprocessors which was followed by a widespread computerization. It is seems that a similar role can be attributed to the introduction of various elements of modern nanotechnology, observed with a fast progress since beginning of this century. It concerns all areas of the applications of analytical chemistry, including also progress in flow analysis, which are being developed since the middle of 20th century. Obviously, it should not be omitted the developed earlier and analytically applied planar structures like lipid membranes or self-assembled monolayers They had essential impact prior to discoveries of numerous extraordinary nanoparticles such as fullerenes, carbon nanotubes and graphene, or nanocrystalline semiconductors (quantum dots). Mostly, due to catalytic effects, significantly developed surface and the possibility of easy functionalization, their application in various stages of flow analytical procedures can significantly improve them. The application of new nanomaterials may be used for the development of new detection methods for flow analytical systems in macro-flow setups as well as in microfluidics and lateral flow immunoassay tests. It is also advantageous that quick flow conditions of measurements may be helpful in preventing unfavorable agglomeration of nanoparticles. A vast literature published already on this subject (e.g. almost 1000 papers about carbon nanotubes and flow-injection analytical systems) implies that for this reviews it was necessary to make an arbitrary selection of reported examples of this trend, focused mainly on achievements reported in the recent decade.

Cu/Au nanoclusters with peroxidase-like activity for chemiluminescence detection of α-amylase

Herein, a novel chemiluminescence method was developed for efficient and sensitive detection of α-amylase activity. α-Amylase is closely related to our life, and α-amylase concentration is a marker for the diagnosis of acute pancreatitis. In this paper, Cu/Au nanoclusters with peroxidase-like activity were prepared using starch as a stabilizer. Cu/Au nanoclusters can catalyze H₂O₂ to generate reactive oxygen species and increase the CL signal. The addition of α-amylase makes the starch decompose and causes the nanoclusters to aggregate. The aggregation of the nanoclusters caused them to increase in size and decrease in the peroxidase-like activity, resulting in a decrease in the CL signal. α-Amylase was detected by the CL method of signal changes caused by dispersion-aggregation in the range of 0.05-8 U mL^-1 with a low detection limit of 0.006 U mL^-1. The chemiluminescence scheme based on the luminol-H₂O₂-Cu/Au NC system is of great significance for the sensitive and selective determination of α-amylase in real samples, and the detection time is short. This work provides new ideas for the detection of α-amylase based on the chemiluminescence method and the signal lasts for a long time, which can realize timely detection.

Ring-Oven-Assisted In Situ Synthesis of Metal-Organic Frameworks on the Lab-On-Paper Device for Chemiluminescence Detection of Nitrite in Whole Blood

In situ synthesis of metal-organic frameworks (MOFs) on flexible materials for the fabrication of functional platforms and micro-devices is challenging. The time-/precursor-consuming procedure and uncontrollable assembly are stumbling blocks for constructing this platform. Herein, a novel in situ MOF synthesis method on paper substrates by use of the ring-oven-assisted technique was reported. Utilizing the ring-oven's heating and washing function, MOFs can be synthesized in 30 min on the designated position of paper chips with extremely low-volume precursors. The principle of this method was explained by steam condensation deposition. The MOFs' growth procedure was theoretically calculated by crystal sizes and the results conformed to the Christian equation. As different MOFs (Cu-MOF-74, Cu-BTB, Cu-BTC) can be synthesized successfully on paper-based chips, the ring-oven-assisted in situ synthesis method has great generality. Then, the prepared Cu-MOF-74 loading paper-based chip was applied to the chemiluminescence (CL) detection of nitrite (NO₂^-), based on the catalysis effect of Cu-MOF-74 on the NO₂^--H₂O₂ CL system. Also, by the delicate design of the paper-based chip, NO₂^- can be detected with the detection limit (DL) of 0.5 nM in whole blood samples without sample pretreatment. This work establishes a distinctive method for the in situ synthesis of MOFs and the application of MOFs on paper-based CL chips.

A novel enzyme-free long-lasting chemiluminescence system based on a luminol functionalized β-cyclodextrin hydrogel for sensitive detection of H2O2 in urine and cells

A novel long-lasting chemiluminescent (CL) hydrogel (β-CD@luminol-Co²⁺) was synthesized by embedding luminol and cobalt ions (Co²⁺) into β-cyclodextrin (β-CD) through non-covalent interactions. Due to its porous structure and viscosity, the synthesized β-CD@luminol-Co²⁺ hydrogel exhibited long-lasting CL properties and can emit light for 12 h under both alkaline and neutral conditions. In addition, the CL intensities of β-CD@luminol-Co²⁺ were linear with the logarithm of the hydrogen peroxide (H₂O₂) concentration in the range of 1.0 × 10^-11-1.0 × 10^-7 M, and the limit of detection (LOD) was 0.63 × 10^-11 M and 0.85 × 10^-11 M under alkaline and neutral conditions, respectively. On this basis, an enzyme-free CL sensor based on β-CD@luminol-Co²⁺ was fabricated for the sensitive detection of H₂O₂ in human urine samples under alkaline conditions, and showed good accuracy and recovery. Since β-CD@luminol-Co²⁺ showed good CL properties under neutral conditions, it can be applied to detect H₂O₂ in cells. In order to prolong the emission wavelength of β-CD@luminol-Co²⁺ for better cell imaging, β-CD@luminol-FL-Co²⁺ was prepared by adding fluorescein (FL) to β-CD@luminol-Co²⁺. The as-prepared β-CD@luminol-FL-Co²⁺ also displayed long-lasting CL properties and showed a linear relationship with H₂O₂ concentrations. In addition, the maximum emission wavelength of β-CD@luminol-FL-Co²⁺ was 520 nm, which was red-shifted by 95 nm compared with β-CD@luminol-Co²⁺. The methyl thiazolyl tetrazolium (MTT) assay results and confocal microscopy images illustrated that β-CD@luminol-FL-Co²⁺ had low toxicity and can be taken up by A549 cells. Finally, β-CD@luminol-FL-Co²⁺ was successfully applied for CL imaging and detection of intracellular H₂O₂ in A549 cells under neutral conditions. This enzyme-free long-lasting CL system with high sensitivity can also be extended to real-time monitoring of H₂O₂in vivo.

Development of lucigenin-N-hydroxyphthalimide chemiluminescence system and its application to sensitive detection of Co2

N-hydroxyphthalimide (NHPI) is an efficient organic catalyst and an important chemical raw material which can be used as an intermediate in organic synthesis of drugs and pesticides. In this study, NHPI has been used as a coreactant of lucigenin chemiluminescence (CL) for the first time. The CL of the developed system is significantly enhanced in the presence of Co²⁺. Therefore, we developed a novel lucigenin-NHPI CL method coupled with flow injection analysis for the sensitive, precise, and selective determination of Co²⁺. The linear range of this method is 1-1000 nM, and the detection limit is 67 pM (S/N = 3). In addition, this method has a good selectivity for Co²⁺. It has been applied to the detection of Co²⁺ in lake water, and the standard recovery rate is 95.9-103.2%, indicating that the method is feasible.

Synthesis of rod-like CeO2 nanoparticles and their application to catalyze the luminal-O2 chemiluminescence reaction used in the determination of oxcarbazepine and ascorbic acid

Rod-like CeO₂ nanoparticles (NPs) were produced by the quick precipitation approach and employed as a catalyzer to increase the chemiluminescence (CL) intensity of the luminol-O₂ reaction. The transmission electron microscopy (TEM) images of the CeO₂ NPs showed that rod-like particles with the length and diameter about 15 nm and 5 nm, respectively, were produced. Furthermore, pharmaceuticals including oxcarbazepine (OXP) and ascorbic acid (AA) showed an inhibitory effect against the CL intensity such that the more concentration of the pharmaceuticals, the less was the CL intensity. Therefore, the new CeO₂ NPs-luminol-O₂ CL reaction was developed to determine OXP and AA in the pharmaceutical formulations. It is the first CL method established for the quantification of OXP. The linear dynamic range of this method for OXP was from 6.0 × 10^-7 to 6.0 × 10^-5 mol L^-1 and for AA from 1.0 × 10^-6 to 1.0 × 10^-4 mol L^-1.

Application progress of magnetic molecularly imprinted polymers chemical sensors in the detection of biomarkers

Specific recognition and highly sensitive detection of biomarkers play an essential role in identification, early diagnosis and prevention of many diseases. Magnetic molecularly imprinted polymers (MMIPs) have been widely used to capture biomimetic receptors for targets in various complex matrices due to their superior recognition ability, structural stability, and rapid separation characteristics, which overcome the existing deficiencies of traditional recognition elements such as antibodies, aptamers. The integration of MMIPs as recognition elements with chemical sensors opens new opportunities for the development of advanced analytical devices with improved selectivity and sensitivity, shorter analysis time, and lower cost. Recently, MMIPs-chemical sensors (MMIPs-CS) have made significant progress in detection, but many challenges and development spaces remain. Therefore, this review focuses on the research progress of the sensor based on biomarker detection and introduces the surface modification of the magnetic support material used to prepare high selective MMIPs, as well as the selective extraction of target biomarkers by MMIPs from the complex biological sample matrix. Based on the understanding of optical sensors and electrochemical sensors, the applications of MMIPs-optical sensors (MMIPs-OS) and MMIPs-electrochemical sensors (MMIPs-ECS) for biomarker detection were reviewed and discussed in detail. Moreover, it provides an overview of the challenges in this research area and the potential strategies for the rational design of high-performance MMIPs-CS, accelerating the development of multifunctional MMIPs-CS.

Trimetallic AuPtCo Nanopolyhedrons with Peroxidase- and Catalase-Like Catalytic Activity for Glow-Type Chemiluminescence Bioanalysis

Chemiluminescence (CL) with stable and glowing light emission is vital for the accurate detection of biomarkers. Moreover, the catalyst plays an important role in CL systems. Herein, the trimetallic AuPtCo nanopolyhedrons with peroxidase- and catalase-like catalytic activities are readily synthesized via a one-step reduction method. After reaction with the substrate ABEI and oxidant H₂O₂, the AuPtCo nanozyme can catalyze the CL emission in a flash type. Interestingly, it has been found that the biofunctionalization of the AuPtCo surface can endow the catalytic interface with a slow-diffusion effect, thereby prolonging the emission of glow-type CL. On this basis, two biofunctionalized AuPtCo nanocomposites, named as AuPtCo@Cys and AuPtCo@Ab, are prepared, achieving sensitive and selective detection of H₂O₂ and lipoprotein-associated phospholipase A₂ (Lp-PLA₂), respectively. Further, the proposed glow-type CL assays are successfully applied for the determination of H₂O₂ and Lp-PLA₂ in female vaginal discharge and human serum samples, respectively, which exhibit good correlation with the clinical results. Overall, the trimetallic AuPtCo nanozyme-based glow-type CL analysis has demonstrated as a powerful and robust tool for biomarker analysis, which holds great promise in clinical applications.

Magnetic covalent organic framework immobilized gold nanoparticles with high-efficiency catalytic performance for chemiluminescent detection of pesticide triazophos

Covalent organic frameworks (COFs) are considered to be a promising support material for catalyst due to their highly ordered porous structure. Here, a core-shell structured Fe₃O₄ magnetic covalent organic framework (Fe₃O₄@COF) was synthesized and employed to provide basic sites for immobilization of gold nanoparticles (AuNPs). The AuNPs was in-situ immobilized on the shell of Fe₃O₄@COF via a citrate reducing method. The Fe₃O₄@COF-AuNP had convenient magnetic separability and exhibited excellent mimicking peroxidase-like activity in catalyzing chemiluminescence (CL) reaction of luminol with hydrogen peroxide (H₂O₂). With acetylcholine chloride (ACh) as substrate of acetylcholinesterase (AChE), a CL method was exploited for sensitive detection of organophosphorus pesticide triazophos due to its irreversible inhibiting effect on the AChE activity and subsequently influences the production of H₂O₂ under the condition of choline oxidase (ChOx). This method gave a good linearity for triazophos in the range of 5.0-300.0 nmol L^-1, and a limit of detection (LOD) of 1 nmol L^-1 was acquired. The applicability of this method was verified by the determination of triazophos in different spiked vegetable samples.

Ultrasensitive On-Field Luminescence Detection Using a Low-Cost Silicon Photomultiplier Device

The availability of portable analytical devices for on-site monitoring and rapid detection of analytes of forensic, environmental, and clinical interest is vital. We report the development of a portable device for the detection of biochemiluminescence relying on silicon photomultiplier (SiPM) technology, called LuminoSiPM, which includes a 3D printed sample holder that can be adapted for both liquid samples and paper-based biosensing. We performed a comparison of analytical performance in terms of detectability with a benchtop luminometer, a portable cooled charge-coupled device (CCD sensor), and smartphone-integrated complementary metal oxide semiconductor (CMOS) sensors. As model systems, we used two luciferase/luciferin systems emitting at different wavelengths using purified protein solutions: the green-emitting P. pyralis mutant Ppy-GR-TS (λmax 550 nm) and the blue-emitting NanoLuc (λmax 460 nm). A limit of detection of 9 femtomoles was obtained for NanoLuc luciferase, about 2 and 3 orders of magnitude lower than that obtained with the portable CCD camera and with the smartphone, respectively. A proof-of-principle forensic application of LuminoSiPM is provided, exploiting an origami chemiluminescent paper-based sensor for acetylcholinesterase inhibitors, showing high potential for this portable low-cost device for on-site applications with adequate sensitivity for detecting low light intensities in critical fields.