A highly sensitive and accurate SERS/RRS dual-spectroscopic immunosensor for clenbuterol based on nitrogen/silver-codoped carbon dots catalytic amplification

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).

Innovative quantum dots-based SERS for ultrasensitive reporting of contaminants in food: Fundamental concepts and practical implementations

Food contamination poses serious health risks, compelling the discovery of new methods to guarantee regulatory compliance and build consumer conviction. Surface Enhanced Raman Spectroscopy (SERS) has come into sight as a sophisticated approach for the ultrasensitive discovery of toxins in food and water, proposing non-destructive, quick, and precise analysis. Instantaneously, quantum dots (QDs) are astonishing nanomaterials, characterized by distinctive attributes such as quantum confinement and optical photostability. This article extends a decisive outline of SERS technology, pointing out its amalgamation with QDs and discussing numerous augmentation approaches i.e., chemical enhancement, electromagnetic enhancement, Van Hove singularities, the Brus equation, Förster resonance energy transfer, band gap energy, and quantum yield. The amalgamation of SERS with QDs commands an important promise in international food security and conservational sustainability. Nevertheless, QDs provide several compensations, they also aspect a few concerns, counting probable toxicity, stability problems, and predisposition to interference. To tackle these items, further research is required to synthesize safer, more stable QD materials and to refine protocols for practical real-world applications. While some reviews on SERS have been published recently, to our knowledge, the current review is the first one dedicated to QDs-assisted SERS in food safety.

Carbon Quantum Dots in Biomedical Applications: Advances, Challenges, and Future Prospects

Carbon quantum dots (CQDs) represent a rapidly emerging class of nanomaterials with significant potential in biomedical applications due to their tunable fluorescence, high biocompatibility, and versatile functionalization. This review focuses on the recent progress in utilizing CQDs for drug delivery, bioimaging, biosensing, and cancer therapy. With their unique optical properties, such as tunable fluorescence, high quantum yield, and photostability, CQDs enable precise bioimaging and sensitive biosensing. Their small size, biocompatibility, and ease of surface functionalization allow for the development of targeted drug delivery systems, enhancing therapeutic precision and minimizing side effects. In cancer therapy, CQDs have shown potential in photodynamic and photothermal treatments by generating reactive oxygen species under light exposure, selectively targeting cancer cells while sparing healthy tissues. Furthermore, CQDs’ ability to penetrate biological barriers including the blood–brain barrier opens new possibilities for delivering therapeutic agents to hard‐to‐reach areas, such as tumors or diseased tissues. However, challenges such as optimizing synthesis, ensuring long‐term stability, and addressing safety concerns in biological environments remain critical hurdles. This review discusses current efforts to overcome these barriers and improve CQD performance in clinical settings, including scalable production methods and enhanced biocompatibility. As research progresses, CQDs are expected to play an important role in improving healthcare by offering more targeted treatment options and contributing to advancements in personalized medicine.

Mxene Quantum Dot Nanosurface Molecularly Imprinted Polymer Resonance Rayleigh Scattering Probe for Highly Sensitive and Selective Determination of Thiocyanate

In this article, a nanosurface molecularly imprinted polymer (MQD@MIP) resonance Rayleigh scattering (RRS) spectral probe for SCN- was prepared by sol-gel method, using Mxene quantum dot as a matrix, thiocyanate (SCN-) as a template ion, (3-aminopropyl) triethoxysilane (APTES) as a functional monomer, tetraethoxysilane (TEOS) as the cross-linker, and ammonia as the initiator. The probe produced an RRS peak at 370 nm and exhibits a strong RRS energy transfer (RRS-ET) effect when the MQD@MIP probe identifies SCN-. As the concentration of SCN- increased, the RRS-ET was enhanced, and the signal value of the system decreased linearly at 370 nm, with a determination range of 0.87-5.22 μg/L, and a detection limit of 0.37 μg/L SCN-. This detection method has the characteristics of simplicity, sensitivity, and specific recognition. The RRS method was used to determine SCN- in the sample, with relative standard deviation of 1.95-10.98% and recovery of 89.0-102.8%.

Application of Surface-Enhanced Raman Spectroscopy Combined with Immunoassay for the Detection of Adrenoceptor Agonists

Rapid, sensitive, and accurate detection of adrenoceptor agonists is a significant research topic in the fields of food safety and public health. Immunoassays are among the most widely used methods for detecting adrenoceptor agonists. In recent years, surface-enhanced Raman spectroscopy combined with immunoassay (SERS-IA) has become an effective technique for improving detection sensitivity. This review focuses on the innovation of Raman reporter molecules and substrate materials for the SERS-IA of adrenoceptor agonists. In addition, it also investigates the challenges involved in potentially applying SERS-IA in the detection of adrenoceptor agonists. Overall, this review provides insight into the design and application of SERS-IA for the detection of adrenoceptor agonists, which is critical for animal-derived food safety and public health.

Colorimetric-SERS dual-mode sensing of Pb(II) ions in traditional Chinese medicine samples based on carbon dots-capped gold nanoparticles as nanozyme

Peroxidase (POD)-mimicking nanozymes have got great progress in the sensing field, but most nanozyme assaying systems are built with a single-signal output mode, which is vulnerable to the effect of different factors. Thus, establishment of a dual-signal output mode is necessary for acquiring dependable and durable performance. This work described an Fe doped noradrenaline-based carbon dots and Prussian blue (Fe,NA-CDs/PB) nanocomposite as a POD-like nanozyme and modified gold nanoparticles (AuNPs) for the colorimetric and surface-enhanced Raman scattering (SERS) dual-mode sensor of Pb(II) in traditional Chinese medicine samples. With 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 3,3',5,5'-tetramethylbenzidine (TMB) as the substrates, it was found that the addition of Pb(II) inhibited the POD-like activity of Fe,NA-CDs/PB and AuNPs, so it was used for colorimetric and SERS dual-mode assays. The POD-like activity was shown to be a "ping-pong" catalytic mechanism, whereas the addition of Pb(II) produced noncompetitive inhibition with modulatory effects on Fe,NA-CDs/PB. The linear response range for colorimetric and SERS sensor detection of Pb(II) was 0.01-1.00 mg/L with the detection limit of 5 μg/L and 8 μg/L, respectively. This dual-mode detection system shows excellent selectivity. More importantly, the Pb(II) in traditional Chinese medicine samples have successfully assayed with good recovery from 90.4 to 108.9 %.

Advance in Detection Technique of Lean Meat Powder Residues in Meat Using SERS: A Review

Food that contains lean meat powder (LMP) can cause human health issues, such as nausea, headaches, and even death for consumers. Traditional methods for detecting LMP residues in meat are often time-consuming and complex and lack sensitivity. This article provides a review of the research progress on the use of surface-enhanced Raman spectroscopy (SERS) technology for detecting residues of LMP in meat. The review also discusses several applications of SERS technology for detecting residues of LMP in meat, including the enhanced detection of LMP residues in meat based on single metal nanoparticles, combining metal nanoparticles with adsorbent materials, combining metal nanoparticles with immunizing and other chemicals, and combining the SERS technology with related techniques. As SERS technology continues to develop and improve, it is expected to become an even more widely used and effective tool for detecting residues of LMP in meat.

Nanosensors: A smart remedy for early detection of clenbuterol contamination in food

Veterinary drugs which are primarily meant for livestock treatment have now been categorised under potential food contaminant due to its unregulated usage and abuse. Their over usage by animal workers lead to production of contaminated animal-based food products which contain veterinary drug residues. These drugs are also misused as growth promoters to enhance the muscle to fat ratio in human body. This review highlights the misuse of such a veterinary drug; Clenbuterol. In this review, we have comprehensively discussed the usage of nanosensors to detect clenbuterol in food samples. Colorimetric, fluorescent, electrochemical, SERS and electrochemiluminescence are major categories of nanosensors that have been utilized for this purpose. The mechanism through which these nanosensors detect clenbuterol have been discussed in detail. The limit of detection and recovery percentage values of each nanosensor have been compared. This review will impart significant information on various nanosensors for clenbuterol detection in real samples.

Advances in Fluorescent Sensing Carbon Dots: An Account of Food Analysis

Illuminating the use of nanomaterials, carbon quantum dots (CQDs) have transfigured the food safety arena because of their bright luminescence, optical properties, low toxicity, and enhanced biocompatibility. Therefore, fluorescent resonance energy transfer, photoinduced electron transfer, and an internal filtering effect mechanism allow precise detection of food additives, heavy metal ions, pathogenic bacteria, veterinary drug residues, and food nutrients. In this review, we describe the primal mechanism of CQD-based fluorescence sensors for food safety inspection. This is an abridged description of the nanodesign and future perspectives of more advanced CQD-based sensors for food safety analysis.

Current Advances in Immunoassays for the Detection of β2-Agonists

β2-agonists are a group of synthetic phenylethanolamine compounds which are traditionally used for treating bronchospasm. These compounds can also increase skeletal muscle mass and decrease body fat. The illegal use of β2-agonists in food-producing animals results in residue of β2-agonists in edible tissues and causes adverse health effects in humans. Thus, the detection of β2-agonists at trace level in complex sample matrices is of great importance for monitoring the abuse of β2-agonists. Many methods have been developed to detect β2-agonists. Among them, a variety of antigen–antibody interaction-based techniques have been established to detect β2-agonists in various samples, including animal feed, urine, serum, milk, tissues and hair. In this review, we summarized current achievement in the extraction of β2-agonists from testing samples and detection of β2-agonists using immunological techniques. Future perspectives were briefly discussed.

Fluorescent sensing platform based on green luminescence carbon dots and AuNPs for clenbuterol detection in pork liver

In this paper, water-soluble green fluorescent carbon dots (G-CDs) were prepared using p-phenylenediamine and glutathione (GSH) as the precursors. The G-CDs exhibit excellent optical properties, and the maximum emission wavelength is located at 522 nm (under 410 nm excitation), which greatly overlaps with the absorption spectrum of AuNPs. Consequently, an effective “off–on” fluorescent sensing platform involved in G-CDs and AuNPs for detection of clenbuterol (CLB) was constructed. The fluorescence of G-CDs was strongly quenched by AuNPs due to the inner filter effect (IFE). As CLB was introduced, the quenched fluorescence intensity was recovered due to the specific interaction between the AuNPs and CLB. The recovered fluorescence intensity is linear to CLB concentration in the range of 13–270 ng mL⁻¹ with a low detection limit of 3.75 ng mL⁻¹. The prepared sensor has been successfully applied for CLB detection in pork liver and could be utilized in food analysis.

Carbon dots (G-CDs) with bright green fluorescence are synthesized by hydrothermal treatment of p-phenylenediamine and glutathione. Employing the G-CDs and AuNPs as sensing platform, a simple fluorescence sensor to detect clenbuterol was established.

Sulfur-doped carbon dots@polydopamine-functionalized magnetic silver nanocubes for dual-modality detection of norovirus

Synergistic dual-mode optical platforms are up-and-coming detection tools in the diagnosis and management of infectious diseases. Here, novel dual-modality fluorescence (FL) and surface-enhanced Raman scattering (SERS) techniques have been integrated into a single probe for the rapid and ultrasensitive detection of norovirus (NoV). The developed FL-SER-based biosensor relies on the dual-signal enhancements of newly synthesized sulfur-doped agar-derived carbon dots (S-agCDs). The antigen-antibody immunoreaction results in forming a core-satellite immunocomplex between anti-NoV antibody-conjugated S-agCDs and polydopamine-functionalized magnetic silver nanocubes [poly (dop)-MNPs-Ag NCs]. By deploying an immunomagnetic enrichment protocol and performing the SERS modality on a single-layer graphene substrate, norovirus-like particles (NoV-LPs) were detected across a wide range of 1 fg mL^-1 - 10 ng mL^-1 with an excellent limit of detection of 0.1 fg mL^-1. The combined advantage of the dual-signaling properties of the biosensor was demonstrated using FL confocal imaging for "hotspots" tracking prior to SERS detection of clinical NoV in fecal specimen down to ⁓10 RNA copies mL^-1. The proposed dual-modality biosensor's performance increases the prospect of a rapid and low-cost sensitive NoV detection and surveillance option for public health.

Fullerene carbon dot catalytic amplification-aptamer assay platform for ultratrace As+3 utilizing SERS/RRS/Abs trifunctional Au nanoprobes

Under microwave conditions, Au-doped carbon dots (CD_Au) were prepared using fullerene as a precursor, and characterized in details. It is found that CD_Au can strongly catalyze the reaction of HAuCl₄-fructose to generate gold nanoparticles (AuNPs). The new nanocatalytic reaction was studied by surface-enhanced Raman scattering (SERS), resonance Rayleigh scattering (RRS) and absorption (Abs) spectrometry. Based on the specific aptamer (Apt_As)-As⁺³ reaction mediated the CD_Au-HAuCl₄-fructose nanoreaction, and the products of AuNPs as SERS/RRS/Abs trifunctional indicator nanoprobes, a new trimode Apt assay strategy was developed for detection of ultratrace As⁺³. A 0.07-0.70, 0.10-0.60 and 0.20-0.70 μg L^-1 were determined by SERS, RRS and Abs, with detection limits (DL) of 0.04, 0.06, 0.10 μg L^-1 respectively. The aptamer-regulation CD_Au catalytic amplification platform can be also used to assay 1.7-13.3 nmol L^-1 Pb²⁺ and 2.0-12 μmol L^-1 Hg²⁺, with DL of 0.80 nmol L^-1 and 0.90 μmol L^-1 respectively.

Ag@WS2 quantum dots for Surface Enhanced Raman Spectroscopy: Enhanced charge transfer induced highly sensitive detection of thiram from honey and beverages

Novel SERS substrates is urgently in demand for rapid and sensitive analysis of toxic agrochemicals from food. In this work, a monodispersed tungsten disulfide quantum dots modified silver nanosphere (Ag@WS₂QD) was prepared and used as SERS substrate. Ag@WS₂QD generated uniform and stable SERS signals within 2 min, displaying great promise in "mixing and reading" detection. Compared to unmodified colloidal silver nanoparticles, 4 times higher analytical enhancement factor was found in Ag@WS₂QD. Density functional theory calculation verified the enhanced charge transfer within the coupling systems of molecule-Ag@WS₂QD. Besides, the unique surface properties are beneficial for the enrichment of specific molecule. Both the chemical extraction and enhanced charge transfer contributes to rapid and sensitive SERS detection of Ag@WS₂QD. A "mixing and reading" SERS method for thiram from honey and four kinds of juice was developed from Ag@WS₂QD, showing great promise for rapid and direct SERS detection for toxic agrochemicals and further applications.

Fluorescent Carbon Quantum Dots-Synthesis,Functionalization and Sensing Application in FoodAnalysis

Carbon quantum dots (CQDs) with stable physicochemical properties are one of theemerging carbon nanomaterials that have been studied in recent years. In addition to the excellentoptical properties such as photoluminescence, photobleaching resistance and light stability, thismaterial also has favorable advantages of good biocompatibility and easy functionalization, whichmake it an ideal raw material for constructing sensing equipment. In addition, CQDs can combinedwith other kinds of materials to form the nanostructured composites with unique properties, whichprovides new insights and ideas for the research of many fields. In the field of food analysis,emerging CQDs have been deeply studied in food composition analysis, detection and monitoringtrace harmful substances and made remarkable research progress. This article introduces andcompares the various methods for CQDs preparation and reviews its related sensing applicationsas a new material in food components analysis and food safety inspection in recent years. It isexpected to provide a significant guidance for the further study of CQDs in the field of foodanalysis and detection. CQDs; synthesis; fluorescent sensing; food analysis.