Radical Pair-Driven Luminescence of Quantum Dots for Specific Detection of Peroxynitrite in Living Cells

In-situ detection of peroxynitrite in a single living cell with electrochemical attosyringe

Peroxynitrite (ONOO-), a key reactive oxygen/nitrogen species, plays a crucial role in signal transduction and physiological homeostasis. However, achieving the determination of ONOO- in a single living cell remains a significant challenge. In this study, we have synthesized blue-emitting carbon dots (CDs) with a specific response to ONOO- via a simple Schiff base crosslinking strategy. The fluorescence of these CDs is efficiently quenched upon interaction with ONOO- due to a strong nitration reaction, enabling highly sensitive and selective detection of ONOO- within a concentration range of 0.06-1.0 μM, with a detection limit as low as 30 nM. Notably, we have developed an electrochemical attosyringe by loading the CDs solution into a nanopipette, facilitating in-situ detection of ONOO- in a single living cell. This approach, which differs from conventional incubation methods, offers rapid infusion and ease of operation, presenting promising opportunities for advancing single-cell analysis and enhancing our understanding of cellular microenvironments.

Ratiometric Fluorescent Probe for Sensitive Tracking of Peroxynitrite during Drug-Induced Hepatotoxicity

As an essential component of reactive oxygen species (ROS), peroxynitrite (ONOO-) plays an indispensable role in redox homeostasis and signal transduction, with anomalous levels implicated in various clinical conditions. Therefore, accurate and rapid detection of intracellular ONOO- levels is crucial for revealing its role in physiological and pathological processes. In this study, we developed a ratiometric fluorescent probe to detect ONOO- levels in biological systems. The probe demonstrated a fast reaction rate (within 15 min), outstanding selectivity, high sensitivity (limit of detection=13.32 nM), and stability in the presence of ONOO-. The proposed probe was successfully used for visualizing endogenous ONOO- in living cells and tracking changes in intracellular ONOO- levels during drug-induced hepatotoxicity using ratiometric fluorescence.

Single-Component Photochemical Afterglow Near-Infrared Luminescent Nano-Photosensitizers: Bioimaging and Photodynamic Therapy

Long afterglow luminescence-guided photodynamic therapy (PDT) performs advantages of noninvasiveness, spatiotemporal controllability, and higher signal to noise ratio. Photochemical afterglow (PCA) system emitting afterglow in an aqueous environment is highly suitable for biomedical applications, but still faces the challenges of poor tissue penetration depth and responsive sensitivity. In this work, two novel compounds, Iso-TPA and ABEI-TPA, are designed and synthesized to integrate the PCA system as a single component by coupling near-infrared (NIR) photosensitizers with singlet oxygen cache units, respectively. Both compounds emit NIR afterglow based on photochemical reaction. ABEI-TPA exhibits higher photoluminescence quantum efficiency with nonconjugated linkage, while Iso-TPA with conjugated linkage possesses better reactive oxygen species generation efficiency to achieve stronger PCA and effective PDT, which is ascribed to stronger intramolecular charge transfer effect of Iso-TPA. Iso-TPA nanoparticles can achieve effective long-lasting NIR afterglow in vivo bioimaging up to 120 s with higher imaging resolution and outstanding PDT efficacy of tumor, exhibiting promising potential on bioimaging and therapy.

Nanomaterials-Induced Redox Imbalance: Challenged and Opportunities for Nanomaterials in Cancer Therapy

Cancer cells typically display redox imbalance compared with normal cells due to increased metabolic rate, accumulated mitochondrial dysfunction, elevated cell signaling, and accelerated peroxisomal activities. This redox imbalance may regulate gene expression, alter protein stability, and modulate existing cellular programs, resulting in inefficient treatment modalities. Therapeutic strategies targeting intra- or extracellular redox states of cancer cells at varying state of progression may trigger programmed cell death if exceeded a certain threshold, enabling therapeutic selectivity and overcoming cancer resistance to radiotherapy and chemotherapy. Nanotechnology provides new opportunities for modulating redox state in cancer cells due to their excellent designability and high reactivity. Various nanomaterials are widely researched to enhance highly reactive substances (free radicals) production, disrupt the endogenous antioxidant defense systems, or both. Here, the physiological features of redox imbalance in cancer cells are described and the challenges in modulating redox state in cancer cells are illustrated. Then, nanomaterials that regulate redox imbalance are classified and elaborated upon based on their ability to target redox regulations. Finally, the future perspectives in this field are proposed. It is hoped this review provides guidance for the design of nanomaterials-based approaches involving modulating intra- or extracellular redox states for cancer therapy, especially for cancers resistant to radiotherapy or chemotherapy, etc.

Self-calibrated HAp:Tb-EDTA paper-based probe with dual emission ratio fluorescence for binary visual and fluorescent detection of anthrax biomarker

Development of the portable device is significant for sensitive and rapid detection of an anthrax biomarker dipicolinic acid (DPA), existing in the B. anthracis. In this work, a novel HAp:Tb-EDTA paper-based ratiometric fluorescent sensor was obtained by a simple one-pot method for rapid and sensitive DPA detection. With the increased DPA concentration, the luminescence intensity of HAp (hydroxyapatite) remained constant, and thus applied as the stable reference signal, while the luminescence signal of Tb3+-EDTA was significantly enhanced due to the antenna effect. Therefore, the HAp:Tb-EDTA paper-based sensor was endowed with self-calibrated and ratiometric fluorescent detection performance for DPA. The proposed sensor showed excellent detection performance with a detection limit as low as 10.8 nM in the linear range of 0.5-30 μM. After combination with a smartphone, rapid visual and fluorescent detection of DPA was achieved. The proposed sensor was successfully applied to detect DPA from B. subtilis spore real samples, showing the application prospects of the paper-based sensors and opening a new horizon to develop novel paper-based point-of-care testing (POCT) devices.

Facile Synthesis of Oxidized Boron Nanosheets for Chemo- and Biosensing

As recently emerging nanomaterials, boron nanosheets (BNSs) have attracted more and more attention in various fields such as supercapacitors, photodetectors, bioimaging, and electrocatalysis due to their advantages of good biological compatibility, environmental friendliness, and good electro-optical properties. However, the study and application of BNSs in chemical and biological sensing are still in the infant stage, mainly due to the requirement of complicated, high-cost, and time-consuming preparation strategies. In this work, a new class of BNSs, namely oxidized-BNSs (i.e., ox-BNSs), were easily and rapidly synthesized by chemically treating boron powder with diluted HNO₃ in a very short time (less than 15 min). The composition, morphology, optical property, and peroxidase mimetic activity of obtained ox-BNSs were investigated in detail. The prepared ox-BNSs were several-layered nanosheets with abundant oxygen-containing groups, emitted blue fluorescence, and possessed good intrinsic peroxidase mimetic activity, based on which a sensitive and selective colorimetric sensor was developed for detection of H₂O₂ and glucose. The new easy preparation strategy and good sensing performances of the prepared ox-BNSs would greatly stimulate the study and application of BNSs in chemo- and biosensing.

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.

An enhanced chemiluminescence hybrids of luminol by sulfonated polyaniline decorated copper-based metal organic frame composite applicable to the measurement of hydrogen peroxide in a wide pH range

Here, sulfonated polyaniline (SPAN) was decorated on the surface of copper-based metal organic frame (HKUST-1) and the composite was functionalized by luminol to construct a chemiluminescence (CL) hybrids (SPAN/HKUST-1@Luminol). The as-prepared SPAN/HKUST-1@Luminol demonstrated a great dispersion and stability performance in aqueous solution. Moreover, the resultant SPAN/HKUST-1@Luminol hybrids exhibited extremely strong CL properties, and the CL quantum yield was 136 times higher than that of luminol. In particular, it exhibited outstanding CL activity not only under alkaline conditions, but also under neutral conditions. The sensitive response of the hybrid to hydrogen peroxide was used to construct CL methods for the detection of hydrogen peroxide at a wide range of pH, with the detection limit of 60 nM at a neutral condition and 25 pM at alkaline condition. Due to strong and stable signal of the SPAN/HKUST-1@Luminol, the CL method provides a viable tool for determination of H₂O₂ in biological systems and enabled the monitoring of stimulated production of H₂O₂ released by living cells.

Development of peroxynitrite-responsive fluorescence probe for recognition of drug-induced liver injury

Peroxynitrite (ONOO^-) as an active substance, is produced during normal physiological process, which plays an important role in maintaining cell REDOX balance and cell function. Moreover, the peroxynitrite is involved in many diseases and especially can be used as a biomarker of drug-induced liver injury (DILI). Therefore, in this work, we synthesized a fluorescent probe JQ-3 for detecting ONOO^-. The results showed the probe JQ-3 possessed excellent selectivity, fast response time (10 min) and low detection limit (32 nM). The probe JQ-3 is almost unaffected by pH, showing the potential application in biological systems. Moreover, the probe JQ-3 can be successfully used for the detection of exogenous and endogenous ONOO^- in living cells and zebrafish. At the same time, the DILI was successfully recognized by visualizing ONOO^- with JQ-3 in living cells and zebrafish. Therefore, the probe JQ-3 provides a potential tool for detecting ONOO^- to understand physiological and pathology processes of disease.

Dithiothreitol-Lucigenin Chemiluminescent System for Ultrasensitive Dithiothreitol and Superoxide Dismutase Detection

1,4-Dithiothreitol (DTT), a highly water-soluble and well-known reducing agent for preservation and regeneration of sulfhydryl groups in biomedical applications, has been developed as an efficient and stable coreactant of lucigenin for the first time. DTT efficiently reacts with lucigenin to generate intense chemiluminescence (CL), eliminating the need for external catalysts to facilitate the lucigenin CL. The DTT-lucigenin CL is approximately 15-fold more intense when compared with the lucigenin-H₂O₂ classical system. Superoxide dismutase (SOD) remarkably quenches the DTT-lucigenin CL. Based on this phenomenon, a newly developed CL approach for the determination of SOD was proposed with a linear range of 0.01-1.5 μg/mL and a limit of detection of 2.2 ng/mL. Various factors affecting the CL emission of the DTT-lucigenin probe were studied and optimized. Plausible mechanistic pathways for the CL coreaction of lucigenin with DTT were proposed and fully discussed. Our proposed method not only has the merit of being selective toward the target analytes but also eliminates the need for the complex synthesis of luminescent probes and facilitates the sensitive detection of SOD in human serum and cosmetics SOD raw material with satisfactory recoveries.

A General Route for Chemiluminescence of n-Type Au Nanocrystals

The photoluminescence, electroluminescence, and electrochemiluminescence from nanocrystals (NCs) have been extensively exploited for both fundamental and applied investigation over two decades, while the understanding of chemiluminescence (CL) from NCs is still far from clear by now. Herein, a general route for triggering CL from NC luminophore is proposed by extensively exploiting the charge transfer between n-type NCs and oxidants. Oxidants, such as K₂S₂O₈, H₂O₂, KMnO₄, and NaClO, can chemically inject the hole onto the valence band (VB) of methionine-capped n-type AuNCs (Met@AuNCs) and enable the occurrence of efficient radiative-charge-recombination between the chemically injected exogenous VB hole and the pre-existed endogenous conduction band (CB) electron, which eventually results in single-color and defect-involved CL with the maximum emission wavelength around 824 nm. The CL of Met@AuNCs/oxidant is qualified for ultrasensitive CL immunoassay in a similar procedure to the biotin-avidin and magnetic separation involved commercial CL immunoassay and exhibits acceptable performance for linearly determining carcinoembryonic antigen from 50 pg/mL to 100 ng/mL with a limit of detection of 10 pg/mL (S/N = 3). This strategy provides a general route to develop nanoparticulate CL luminophores and might eventually enable CL multiplexing assay via extensively exploiting the CL of different wavebands.

Glow and Flash Adjustable Chemiluminescence with Tunable Waveband from the Same CuInS2@ZnS Nanocrystal Luminophore

All commercial chemiluminescence (CL) assays are conducted with either glow or flash CL of eye-visible waveband from chemical luminophores. Herein, glow and flash, as well as waveband adjustable CL from the same nanoparticle luminophore of thiol-capped CuInS₂@ZnS nanocrystals (CIS@ZnS-Thiol), are proposed via extensively exploiting the differed redox nature of CL triggering reagents. Taking thiosalicylic acid (TSA) as the model thiol-capping agent, the electron-injection-initiated charge transfer between CIS@ZnS-TSA and reductant can bring out efficient glow CL while the hole-injection-initiated charge transfer between CIS@ZnS-TSA and oxidant can give off obvious flash CL under optimum conditions. The maximum emission wavelength for CL of CIS@ZnS-TSA is adjustable from 730 nm to 823 nm via employing different triggering agents. Promisingly, the coexistent reductant of N₂H₄·H₂O and oxidant of H₂O₂ can be employed as dual triggering reagents to trigger eye-visible and highly efficient flash CL from CIS@ZnS-TSA. The maximum emission intensity for flash CL of CIS@ZnS-TSA/N₂H₄-H₂O₂ is 101-fold greater than the glow CL of CIS@ZnS-TSA/N₂H₄ and 22-fold greater than the flash CL of CIS@ZnS-TSA/H₂O₂, respectively. The flash CL from CIS@ZnS-TSA/N₂H₄-H₂O₂ is qualified for highly sensitive and selective CL immunoassay in a commercialized typical procedure with the entire operating process manually terminated within 35 min.

Chemiluminescence Measurement of Reactive Sulfur and Nitrogen Species

Significance: Reactive sulfur and nitrogen species such as hydrogen sulfide (H₂S) and nitric oxide (NO^•) are ubiquitous cellular signaling molecules that play central roles in physiology and pathophysiology. A deeper understanding of these signaling pathways will offer new opportunities for therapeutic treatments and disease management. Recent Advances: Chemiluminescence methods have been fundamental in detecting and measuring biological reactive sulfur and nitrogen species, and new approaches are emerging for imaging these analytes in living intact specimens. Ozone-based and luminol-based chemiluminescence methods have been optimized for quantitative analysis of hydrogen sulfide and nitric oxide in biological samples and tissue homogenates, and caged luciferin and 1,2-dioxetanes are emerging as a versatile approach for monitoring and imaging reactive sulfur and nitrogen species in living cells and animal models. Critical Issues: This review article will cover the major chemiluminescence approaches for detecting, measuring, and imaging reactive sulfur and nitrogen species in biological systems, including a brief history of the development of the most established approaches and highlights of the opportunities provided by emerging approaches. Future Directions: Emerging chemiluminescence approaches offer new opportunities for monitoring and imaging reactive sulfur and nitrogen species in living cells, animals, and human clinical samples. Widespread adoption and translation of these approaches, however, requires an emphasis on rigorous quantitative methods, reproducibility, and effective technology transfer. Antioxid. Redox Signal. 36, 337-353.

Hydrazine Hydrate and Dissolved Oxygen-Triggered Near-Infrared Chemiluminescence from CuInS2@ZnS Nanocrystals for Bioassays

The overwhelming majority of commercially available chemiluminescence (CL) assays are conducted in the eye-visible region. Herein, a near-infrared (NIR) aqueous CL strategy was proposed with CuInS₂@ZnS nanocrystals (CIS@ZnS NCs) as emitters. Hydrazine hydrate (N₂H₄·H₂O) could inject electrons into the conduction band of the CIS@ZnS NCs and simultaneously transformed to the intermediate radical N₂H₃^•. N₂H₃^• reduced dissolved oxygen (O₂) to O₂^-•, while the O₂^-• could inject holes into the valence band of the CIS@ZnS NCs. The recombination of electrons and holes at Cu⁺ defects in CIS@ZnS NCs eventually yielded efficient NIR CL at around 824.1 nm, which is the longest waveband for NCs CL to the best of our knowledge. The NIR CL could be conveniently performed in the neutral aqueous medium (pH 7.0) with a quantum yield of 0.0155 Einstein/mol and was successfully employed for constructing a signal-off CL biosensor with ascorbic acid as the analyte as well as a signal-on CL biosensor for determining ascorbate oxidase, which indicates that this NIR CL system has a promising potential for bioassays in diverse ways.

Design and Challenges of Sonodynamic Therapy System for Cancer Theranostics: From Equipment to Sensitizers

As a novel noninvasive therapeutic modality combining low-intensity ultrasound and sonosensitizers, sonodynamic therapy (SDT) is promising for clinical translation due to its high tissue-penetrating capability to treat deeper lesions intractable by photodynamic therapy (PDT), which suffers from the major limitation of low tissue penetration depth of light. The effectiveness and feasibility of SDT are regarded to rely on not only the development of stable and flexible SDT apparatus, but also the screening of sonosensitizers with good specificity and safety. To give an outlook of the development of SDT equipment, the key technologies are discussed according to five aspects including ultrasonic dose settings, sonosensitizer screening, tumor positioning, temperature monitoring, and reactive oxygen species (ROS) detection. In addition, some state-of-the-art SDT multifunctional equipment integrating diagnosis and treatment for accurate SDT are introduced. Further, an overview of the development of sonosensitizers is provided from small molecular sensitizers to nano/microenhanced sensitizers. Several types of nanomaterial-augmented SDT are in discussion, including porphyrin-based nanomaterials, porphyrin-like nanomaterials, inorganic nanomaterials, and organic-inorganic hybrid nanomaterials with different strategies to improve SDT therapeutic efficacy. There is no doubt that the rapid development and clinical translation of sonodynamic therapy will be promoted by advanced equipment, smart nanomaterial-based sonosensitizer, and multidisciplinary collaboration.

Biomimetic Metal-Organic Framework Composite-Mediated Cascade Catalysis for Synergistic Bacteria Killing

Encapsulating nanoparticles/biomolecules into metal-organic freamworks (MOFs) has proven to be highly effective in creating new functions during their applications. However, it is highly desirable yet remains challenging to achieve the synergy of specific functions between the MOF host and guest species. Herein, inspired by the natural multienzyme system, a novel MOF composite biomimetic structure based on the coencapsulation of glucose oxidase (GOx) and l-arginine (l-Arg) into Cu-MOFs (CuBDC) with Fenton-like catalytic activity is designed for achieving the synergistic antibacterial effect. Once activated by GOx-catalyzed glucose oxidation, a large amount of oxygen radicals, toxic ONOO^-, and NO are rapidly produced over this well-designed l-Arg/GOx@CuBDC through a double-cascade reaction. Thanks to the synergy of highly reactive species, outstanding antibacterial effects (bacterial inactivation ≥97%) are observed at very low doses (38 μg mL^-1 for Escherichia coli and 3.8 μg mL^-1 for Staphylococcus aureus). In addition, the in vivo experiment in mice demonstrated that the as-prepared l-Arg/GOx@CuBDC has good biocompatibility, indicating its good potential in practical applications. Such a biomimetic multienzyme system proposes a new design idea for highly efficient antibiosis as well as even therapy for tumors.

Visualization of materials using the confocal laser scanning microscopy technique

The development of materials science always benefits from advanced characterizations. Currently, imaging techniques are of great technological importance in both fundamental and applied research on materials. In comparison to conventional visualization methods, confocal laser scanning microscopy (CLSM) is non-invasive, with macroscale and high-contrast scanning, a simple and fast sample preparation procedure as well as easy operation. In addition, CLSM allows rapid acquisition of longitudinal and cross-sectional images at any position in a material. Therefore, the CLSM-based visualization technique could provide direct and model-independent insight into material characterizations. This review summarizes the recent applications of CLSM in materials science. The current CLSM approaches for the visualization of surface structures, internal structures, spatial structures and reaction processes are discussed in detail. Finally, we provide our thoughts and predictions on the future development of CLSM in materials science. The purpose of this review is to guide researchers to build a suitable CLSM approach for material characterizations, and to open viable opportunities and inspirations for the development of new strategies aiming at the preparation of advanced materials. We hope that this review will be useful for a wide range of research communities of materials science, chemistry, and engineering.

Cu-Doped Carbon Dots as Catalysts for the Chemiluminescence Detection of Glucose

Development of metal-doped carbon dots (CDs) to effectively modulate their electronic properties and surface chemical reactivities is still in its early stage. In this paper, a facile solid-phase synthesis strategy was developed to synthesize Cu-doped CDs (Cu-CDs) using citric acid as the carbon source and Cu(NO₃)₂·3H₂O as the dopant, respectively. The as-prepared Cu-CDs exhibited superior peroxidase-like activity to horseradish peroxidase and were stable under a wide range of pH and temperatures. Consequently, the Cu-CD-based chemiluminescence sensing was applied to sensitively detect glucose with a low detection limit of 0.32 μM, and the recoveries and the relative standard deviation of the serum sample are 87.2-112.2 and 8.16% (n = 6), respectively. Notably, the proposed chemiluminescence sensing was also successfully applied for label-free detection of glucose in complex biological samples, which envisioned its potential applications in clinical diagnosis and other analytical assays.

Real-Time Mapping of Ultratrace Singlet Oxygen in Rat during Acute and Chronic Inflammations via a Chemiluminescent Nanosensor

Sensing nonradiation-induced singlet oxygen (¹ O₂ ) in whole-animal is deemed as one of the most challenging tasks in noninvasive techniques due to the µs level lifetime of ¹ O₂ and quenching by numerous reductants in tissues. Here a distinct chemiluminescent (CL) nanosensor (NTPE-PH) that boasts ultrahigh concentrated CL units in one nanoparticle is reported. Taking advantage of the intramolecular energy transfer mechanism that promises high energy transfer efficiency and the aggregation-induced emission behavior that guarantees high CL amplification, the NTPE-PH sensor is sensitive to a nm level ¹ O₂ . Experiments demonstrate that the NTPE-PH yields a highly selective CL response toward ¹ O₂ among common reactive oxygen species. With proved low cytotoxicity and good animal compatibility, real-time mapping of ultratrace ¹ O₂ in whole-animal during acute and chronic inflammations is first achieved. It is anticipated that the NTPE-PH sensor can be a useful tool for monitoring ¹ O₂ variation during immune response and pathological processes corresponding to different stimuli, even with drug treatment included.

Rapid and green synthesis of cadmium telluride quantum dots with low toxicity based on a plant-mediated approach after microwave and ultrasonic assisted extraction: Synthesis, characterization, biological potentials and comparison study

In this work, a quick, facile and efficient approach was presented for green synthesis of cadmium telluride quantum dots (CdTe QDs) based on an aqueous extract of the Ficus johannis plant. Two extraction methods involving microwave assisted extraction (MWAE; 90 and 270 w; 15 min) and ultrasonic assisted extraction (USAE; 15 min; 45 °C) were performed as eco-friendly, effective, green and fast techniques for the extract preparation of the fruit's plant. The as-prepared plant extracts were used as natural stabilizing precursors in the synthesis of CdTe QDs. The synthesized QDs were characterized using various techniques. The average particle size of the QDs from the X-ray diffraction patterns was calculated to be 1.2 nm. UV-Vis absorption and fluorescence spectroscopic studies show a wide absorption band from 400 to 425 nm and a maximum emission peak around 470 nm, which confirmed the successful synthesis of CdTe QDs via the applied synthetic method. After synthesis and characterization of the samples, the antimicrobial properties, genotoxicity, toxicity and antifungal activities of the as-prepared CdTe QDs were investigated. In addition, antioxidant properties of the samples (QDs and extracts), were evaluated by different antioxidant assays. The results indicate the significant antimicrobial activity of the extract and CdTe QDs samples, with negligible toxicity and genotoxicity impacts.

Observation of the generation of peroxynitrite in mouse liver after acetaminophen overdose with a boronate-based ratiometric fluorescence probe

A ratiometric fluorescent probe, BTPB, for the selective monitoring of hepatic peroxynitrite in situ after acetaminophen overdose has been developed.

A light-initiated chemiluminescent assay for rapid quantitation of allergen-specific IgG4 in clinical samples

BACKGROUND

An increase in allergen-specific IgG₄ (sIgG₄), which serves as a blocking antibody, is associated with acquisition of immune tolerance after immunotherapy. In this study, we developed a rapid, sensitive, and homogeneous immunoassay based on the light-initiated chemiluminescent assay (LICA) technology for quantifying allergen sIgG₄ in serum samples.

METHODS

Allergen sIgG₄ was measured in vitro by incubating the sample with biotinylated allergens and chemiluminescent beads coated with anti-human IgG₄ antibody, followed by the addition of streptavidin-coated sensitizer beads. Multiple tests were performed to optimize the working conditions of the LICA and evaluate its performance.

RESULTS

We established the optimal concentration of biotinylated allergens (250 ng/mL), the optimal dilution range (1:8 for Gal d 1, Gal d 2 sIgG₄ and 1:4 for Gal d 3, Gal d 4 sIgG₄), and the optimal incubation time (20 min for Gal d 1, Gal d 2 sIgG₄ and 40 min for Gal d 3, Gal d 4 sIgG₄). The lower limit of quantification (LLOQ) was 0.261 ng/mL. The coefficient variation (CV) of the LICA was <10%. The assay was unaffected by general interfering substances at physiological concentrations. It exhibited excellent accuracy to detect allergen-sIgG₄ in human serum. Additionally, we demonstrated that the levels of Gal d 1, Gal d 2, and Gal d 3-sIgG₄ were significantly higher in the egg allergy group (p < .05), but no differences were found between the groups for Gal d 4-sIgG₄.

CONCLUSIONS

The LICA demonstrated satisfactory performance and can be used for quantifying allergen sIgG₄ in clinical practice.

Measurement of Cell-Matrix Adhesion at Single-Cell Resolution for Revealing the Functions of Biomaterials for Adherent Cell Culture

Cell adhesion is essential for a cell to maintain its functions, and biomaterials acting as the extracellular matrix (ECM) play a vital role. However, conventional methods for evaluating the functions of biomaterials become insufficient and sometimes incorrect when we give a deeper insight into single-cell research. In this work, we reported a novel methodology for the measurement of cell-matrix adhesion at single-cell resolution that could precisely evaluate the functions of biomaterials for adherent cell culture. A microfludic device, a live single-cell extractor (LSCE), was used for cell extraction. We applied this method to evaluate various modified biomaterials. The results indicated that poly(l-polylysine) (PLL)-coated glass and fibronection (FN)-coated glass slides showed the best biocompatibility for adherent cell culture following by the (3-aminopropyl)triethoxysilane (APTES)-coated glass, while piranha solution treated glass slide and octadecyltrichlorosilane (OTS)-coated glass showed weak biocompatibilities. Furthermore, APTES, PLL, and FN modifications enhanced the cell heterogeneity, while the OTS modification weakened the cell heterogeneity compare to the initial piranha solution treated glass. The method not only clarified the cell-matrix adhesion strength at single-cell resolution but also revealed the influences of biomaterials on cell-matrix adhesion and heterogeneity of cell-matrix adhesion for adherent cell culture. It might be a general strategy for precise evaluation of biomaterials.

Application of carbon dots as efficient catalyst for the green oxidation of phenol: Kinetic study of the degradation and optimization using response surface methodology

The reactivity of bio-polymer based nano carbon dots (NCDs) was studied for catalyzing the decomposition of H₂O₂ to generate free hydroxyl radicals and consequently its applicability in the removal of phenol. To the best of our knowledge, for the first time, this work reports that bio-polymer based NCDs could activate H₂O₂ and yielding more than 99% phenol degradation within 20 min in the presence of 12 mmol H₂O₂. Herein, a simple hydrothermal carbonization route was employed for the synthesis of NCDs. The surface morphology, functional groups and crystallinity of the NCDs are studied. SEM images show the NCDs with spherical shape. The graphitic nature of the NCDs was evident from the XRD pattern. The presence of many surface functional groups is confirmed by FT-IR spectra. The influences of three independent operating parameters involving hydrogen peroxide concentration (4-12 mmol), reaction time (10-20 min) and catalyst amount (50-1000 ppm) on the phenol oxidation rate by two NCDs were examined using response surface methodology (RSM). Terephthalic acid (TA) dosimetry demonstrates that the as-prepared NCDs can produce hydroxyl radicals from H₂O₂, and hence catalyze the oxidation of phenol. Finally, the reusability of the NCDs catalysts was examined and the produced catalysts exhibit good recyclability.

A visible-near-infrared fluorescent probe for peroxynitrite with large pseudo-Stokes and emission shift via through-bond energy and charge transfers controlled by energy matching

We reported a visible-near-infrared fluorescent probe for peroxynitrite detection with large pseudo-Stokes and emission shifts, based on through-bond energy transfer (TBET) in combination with intramolecular charge transfer (ICT). Pyrene was chosen as a fluorophore (acceptor), which has monomer/excimer fluorescence characteristics. A conjugated 1,2-dimethylenehydrazine structure was a linker and phenyl boronate was selected as a reaction site (donor) to design the probe (Py-PhB) using the chemical transformation from boronate to phenol, which results in the increase of the energy of the donor to match the energy of the acceptor and simultaneously achieves TBET and ICT between the donor (phenolate) and the acceptor (pyrene), leading to a fluorescence 'OFF-ON' in a red-shifted region and a large emission shift. The results show that the probe exhibits high selectivity to ONOO^- with a detection limit of 3.54 μM. Favorable ICT from phenolate to pyrene makes the probe possess a large monomer emission shift (183 nm), red-shifted to organe-red light (598 nm). TBET ensures the probe with a large pseudo-Stokes shift of 244 nm. Furthermore, its excimer emits a near-infrared light (720 nm), which is extremely beneficial for bioimaging. In short, this probe offers a novel design strategy for designing the TBET fluorescent sensors emitting red or NIR light with large pseudo-Stokes and emission shifts.

Insights into the role of nanostructure in the sensing properties of carbon nanodots for improved sensitivity to reactive oxygen species in living cells

The surface states of carbon nanodots (CDs) were engineered by controlling the chemical structure on the surface of the CDs, which play an important role in the chemiluminescence sensing properties of CDs towards peroxynitrite. Their application in monitoring exogenous and endogenous release of peroxynitrite in living cells is demonstrated.

Dual fluorescence nanoconjugates for ratiometric detection of reactive oxygen species in inflammatory cells

Reactive oxygen species (ROS) are largely produced under pathological situations. To understand the etiology of disease, it is urgent to develop efficacious probes for detecting ROS. Herein, a novel nanoconjugate detection system constructed from gold clusters (AuNCs) and quantum dots (QDs) for fluorescence ratiometric-sensing ROS was reported. Upon interacting with ROS, the red emission fluorescence (645 nm from QDs) in the detection system gradually decreased, while the green fluorescence (480 nm from AuNCs) changed little. The fluorescence ratio at the 2 wavelengths (I_{480 nm} /I_{645 nm} ) was linearly correlated with the ROS, which could be used for the real-time ratiometric detection of ROS. The developed nanoconjugates could be applied to monitor the ROS in inflammatory cells for its ability of generating abundant ROS and uptaking ability to nanoparticles. The stimulated ROS in inflammatory cells were monitored by AuNC-QD and the results were consistent with the traditional 2', 7'-dichlorofluorescin diacetate method, confirming the reliability of the developed method. Featured with the merits of higher photostability, low background, high accuracy of ratiometric detection, the AuNC-QD conjugate demonstrated its potential to be the probe for real-time ROS detection in inflammatory cells.

A chemiluminescent probe for cellular peroxynitrite using a self-immolative oxidative decarbonylation reaction

Peroxynitrite is a damaging agent of oxidative stress that has been difficult to monitor in living cells. Here, an isatin-based chemiluminescent probe for peroxynitrite is reported.

Peroxynitrite (ONOO^–) is a highly reactive oxygen species which has been recognized as an endogenous mediator of physiological activities like the immune response as well as a damaging agent of oxidative stress under pathological conditions. While its biological importance is becoming clearer, many of the details of its production and mechanism of action remain elusive due to the lack of available selective and sensitive detection methods. Herein, we report the development, characterization, and biological applications of a reaction-based chemiluminescent probe for ONOO^– detection, termed as PNCL. PNCL reacts with ONOO^–via an isatin moiety through an oxidative decarbonylation reaction to initiate light emission that can be observed instantly with high selectivity against other reactive sulphur, oxygen, and nitrogen species. Detailed studies were performed to study the reaction between isatin and ONOO^–, which confirm selectivity for ONOO^– over NO₂˙. PNCL has been applied for ONOO^– detection in aqueous solution and live cells. Moreover, PNCL can be employed to detect cellular ONOO^– generated in macrophages stimulated to mount an immune response with lipopolysaccharide (LPS). The sensitivity granted by chemiluminescent detection together with the specificity of the oxidative decarbonylation reaction provides a useful tool to explore ONOO^– chemistry and biology.

Recent advances and developments on integrating nanotechnology with chemiluminescence assays

Chemiluminescence (CL) techniques are extensively utilized for detection of analytes due to their high sensitivity, rapidity and selectivity. With the advent of nanotechnology and incorporation of the nanoparticles in the CL system has revolutionized the assays due to their unique optical and mechanical properties. Several CL-based reactions have been developed where these nanoparticle based CL sensors have evolved as excellent prospects for sensing in various analytical applications. This review article addresses the nanoparticles based CL detection system that are recently developed, the mechanisms has been summarized and the role of luminophors have been discussed. This article critically analyzes the optimal conditions for the CL detection along with quantitative assessment of the analytes. We have included the use of semiconductor nanoparticles, metal nanoparticles, graphene based nanostructures, mesoporous nanospheres, layered double hydroxides, clays for CL detection. The scope and application of these nanoscale material based CL system in various branches of science and technology including chemistry, biomedical applications, pharmaceutics, food, environmental and toxicological applications has been critically summarized.

Quantum dots: from fluorescence to chemiluminescence, bioluminescence, electrochemiluminescence, and electrochemistry

During the past decade, nanotechnology has become one of the major forces driving basic and applied research. As a novel class of inorganic fluorochromes, research into quantum dots (QDs) has become one of the fastest growing fields of nanotechnology today. QDs are made of a semiconductor material with tunable physical dimensions as well as unique optoelectronic properties, and have attracted multidisciplinary research efforts to further their potential bioanalytical applications. Recently, numerous optical properties of QDs, such as narrow emission band peaks, broad absorption spectra, intense signals, and remarkable resistance to photobleaching, have made them biocompatible and sensitive for biological assays. In this review, we give an overview of these exciting materials and describe their potential, especially in biomolecules analysis, including fluorescence detection, chemiluminescence detection, bioluminescence detection, electrochemiluminescence detection, and electrochemical detection. Finally, conclusions are made, including highlighting some critical challenges remaining and a perspective of how this field can be expected to develop in the future.

Activatable QD-Based Near-Infrared Fluorescence Probe for Sensitive Detection and Imaging of DNA

Accurate detection of DNA is essential for the precise diagnosis of diseases. Here we report an activatable near-infrared (NIR) fluorescence nanoprobe (QD-Al-GFLX) composed of NIR quantum dots (QDs) and Al(III)-gatifloxacin (Al-GFLX) complexes for the sensitive detection of double-stranded DNA (dsDNA) both in aqueous solution and in living cells. We demonstrated that the initial strong NIR fluorescence of QDs in QD-Al-GFLX was quenched by the Al-GFLX complex via a photoinduced electron transfer (PET) mechanism. Upon interaction with dsDNA, the high binding affinity between dsDNA and Al-GFLX complex could trigger QD-Al-GFLX dissociation, which could eliminate the PET process, resulting in significant enhancement of NIR fluorescence. QD-Al-GFLX was sensitive and specific to detect dsDNA in aqueous solution, with a detection limit of 6.83 ng/mL. The subsequent fluorescence imaging revealed that QD-Al-GFLX holds a high ability to enter into live cells, generating strong NIR fluorescence capable of reporting on dsDNA levels. This study highlighted the potential of using QD-Al-GFLX nanoprobe for the real-time detection and imaging of dsDNA in living cells.