Selective and sensitive detection of tartrazine in beverages by sulfur quantum dots with high fluorescence quantum yield

CdTe@ZnS quantum dots for rapid detection of organophosphorus pesticide in agricultural products

Organophosphorus pesticides (OPPs) constitute the most widely employed class of pesticides. However, the prevalent use of OPPs, while advantageous, raises concerns due to their toxicity, posing serious threats to food safety. Chemical sensors utilizing quantum dots (QDs) demonstrate promising applications in rapidly detecting OPPs residues, thereby facilitating efficient inspection of agricultural products. In this study, we employ an aqueous synthesis approach to prepare low toxic CdTe@ZnS QDs with stable fluorescence properties. To mitigate the risk of imprecise measurements stemming from the inherent susceptibility of fluorescence to quenching, we have adopted the principle of fluorescence resonance energy transfer (FRET) for the construction of the turn-on quantum dot sensor. With a detection limit for chlorpyrifos as low as 10 ppb (10 μg/L), the QDs sensor exhibits notable resistance to interference from various pesticides. Application of this system to detect organophosphorothioate pesticides in apples produced results consistent with those obtained from high-performance liquid chromatography (HPLC) detection, affirming the promising application prospects of this sensing system for the rapid detection of OPPs residues.

Advances in the synthesis and properties of sulfur quantum dots for food safety detection and antibacterial applications

Food safety is closely related to human health and has become a worldwide, pressing concern. Food safety analysis is essential for ensuring food safety. Sulfur quantum dots (SQDs), a new type of zero-dimensional metal-free nanomaterials, have recently become the focus of scientific research due to their good luminescence properties, dispersibility, biocompatibility, and inherent antibacterial properties. This review focuses on recent advances in SQDs, with emphasis on their practical applications in the food field. First, commonly used methods for the synthesis of SQDs are presented, including traditional and emerging strategies. The properties of SQDs are then analyzed in detail, particularly their luminescence properties, catalytic activities, and reducing properties. Next, the use of SQDs in food safety detection and antibacterial fields are elaborated. Finally, this review discusses the challenges associated with the use of SQDs in food safety detection and antimicrobial applications.

Nitrogen-doped carbon quantum dots as dual mode fluorescence sensors for the determination of food colorant quinoline yellow

Quinoline yellow (QY), as a food coloring agent, will consume a large number of detoxifying substances in the body after being ingested by the human body, interfering with the normal metabolic functions of the human body, and may cause allergies, diarrhea and other symptoms, as well as a certain degree of carcinogenicity, posing a great threat to human health. As a result, it is critical to develop a fast, sensitive, and effective approach to determining quinoline yellow in food. In this study, carbon dots (N-CQDs) with high fluorescence quantum yield were prepared and used to determine the QY content using the dual mode of internal filtering effect and fluorescence emission shift detection. Both methods showed good linearity in the range of QY concentration of 0.3-3.2 μM, and the detection limits were classified as 2.6 nM and 0.18 μM. In addition, in order to achieve visual detection of QY, fluorescent test strips were constructed using the carbon dots and non-fluorescent qualitative filter paper to make the detection of QY more convenient. This probe presents a novel way for detecting quinoline yellow in food analysis.

Development of a Novel Sulfur Quantum Dots: Synthesis, 99mTc Radiolabeling, and Biodistribution

Sulfur quantum dots (SQDs) as free heavy metal element quantum dots have promising applications in diagnosis and therapy; however, SQDs' in vivo biodistribution has not been studied. In the current study, SQDs were synthesized directly from cheap sublimated sulfur powder via a one-pot solvothermal method, and sucrose was used as a stabilizer to enhance stability and biocompatibility. The as-obtained SQDs with an average size of 4.6 nm exhibited great water dispersity, highly favorable quantum yield (21.5%), and uniformly spherical shape which were confirmed by UV-Vis, fluorescence spectrophotometer, TEM, and FESEM/EDX/PSA analyses. Moreover, the as-synthesized SQDs had very low cytotoxicity based on cancer (C26) and normal (L929) cell lines via MTT assay. And also, SQDs were radio-labeled directly by Technetium-99m (99mTc), which had good stability ranging from 86 to 99% in PBS and human serum. The SQDs' cell uptake on C26 and L929 cell lines demonstrated that cancer cells had more uptake than normal cells by increasing concentrations. Moreover, SQDs' in vivo biodistribution results displayed high kidney dose accumulation and rapid renal clearance, making them suitable for imaging and therapeutic applications.

Synthesis of Bio-Base Fluorescence Carbon Dots for Selective Detection of Tartrazine and Sunset Yellow in Food Samples

A green, economical and simple method for the preparation of water-soluble, high-fluorescent carbon quantum dots (CQDs) has been developed via hydrothermal process using pomelo peels as carbon source. The synthesized CQDs were characterized by transmission electron microscopy (TEM), X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), UV - vis absorption spectra and fluorescence spectrophotometer. The results reveal that the as-prepared C-dots were spherical shape with an average diameter of 2.64 nm and emit bright blue photoluminescence (PL) with a quantum yield of approximately 3.63%. The surface of the C-dots was rich in hydroxyl groups and presented various merits including excellent photostability, low toxicity, and satisfactory solubility. Additionally, we found that two widely used synthetic food colorants, tartrazine and sunset yellow, could result in a strong fluorescence quenching of the C-dots, The possible mechanisms are caused by different ratios of inner filter and static quenching effects. According to this property, This study attempts to establish an analytical method for the determination of tartrazine and sunset yellow using carbon quantum dots as fluorescent probe. A linear relationship was found in the range of 0-100 µM tartrazine and sunset yellow with the detection limit(3σ/k) of 0.65 nM and 1.7 nM. The relative standard deviation (RSD) was 3.5% (tartrazine) and 3.0% (sunset yellow).This observation was further successfully applied for the determination of tartrazine and sunset yellow in food samples collected from local markets, and the recovery rates of the two ranges from 79% to 117.8 and 81 -103.5%, respectively. suggesting its great potential toward food routine analysis.

A comprehensive exploration of tartrazine detection in food products: Leveraging fluorescence nanomaterials and electrochemical sensors: Recent progress and future trends

Azo dyes are widely used as food coloring agents because of their affordability and stability. Examples include brilliant blue, carmoisine, sunset yellow, allura red, and tartrazine (Tar), etc. Notably, Tar is often utilized in hazardous food goods. They are frequently flavoured and combined with food items, raising the likelihood and danger of exposure. Therefore, detecting Tar in food is crucial to prevent health risks. Fluorescence nanomaterials and electrochemical sensors, known for their high sensitivity, affordability, simplicity, and speed, have been widely adopted by researchers for Tar detection. This comprehensive paper delves into the detection of Tar in food products. It extensively covers the utilization of advanced carbon-based nanomaterials, including CDs, doped CDs, and functionalized CDs, for sensitive Tar detection. Additionally, the paper explores the application of electrochemical sensors. The paper concludes by addressing current challenges and prospects, emphasizing efforts to enhance sensitivity, and selectivity for improved food safety.

Research Progress in the Synthesis of Carbon Dots and Their Application in Food Analysis

Food safety is connected to public health, making it crucial to protecting people's health. Food analysis and detection can assure food quality and effectively reduce the entry of harmful foods into the market. Carbon dots (CDs) are an excellent choice for food analysis and detection attributable to their advantages of good optical properties, water solubility, high chemical stability, easy functionalization, excellent bleaching resistance, low toxicity, and good biocompatibility. This paper focuses on the optical properties, synthesis methods, and applications of CDs in food analysis and detection, including the recent advances in food nutritional composition analysis and food quality detection, such as food additives, heavy metal ions, foodborne pathogens, harmful organic pollutants, and pH value. Moreover, this review also discusses the potentially toxic effects, current challenges, and prospects of CDs in basic research and applications. We hope that this review can provide valuable information to lay a foundation for subsequent research on CDs and promote the exploration of CDs-based sensing for future food detection.

Adsorption kinetics of 20 glucocorticoids at environmentally relevant concentrations in wastewater by powdered activated carbons and development of surrogate models

Glucocorticoids (GCs) are widely used in the treatment of the coronavirus disease of 2019 (COVID-19), and the toxicity of GCs to aquatic organisms has aroused widespread concern. Powdered activated carbon (PAC) has proven effective in removing various trace organic pollutants. In this study, the adsorption behaviors of 20 typical GCs onto PACs were investigated at environmentally relevant concentrations (ng/L) in real wastewater, using four commercially available PACs (HDB, WPH, 20BF, PWA). The results showed that PAC adsorption was feasible for GC removal at ng/L concentrations. After adsorption for 60 min, the GC removal efficiencies obtained by HDB, WPH, 20BF, and PWA were 90-98 %, 89-97 %, 84-96 %, and 71-90 %, respectively. The adsorption processes of 20 GCs on PACs were well fitted by the pseudo-second-order kinetics model (with R ² >0.98). Among the four PACs, HDB achieved the highest rates because of the electrostatic attraction between HDB (positively charged) and the complex of GCs and natural organic matter (GC-NOM, negatively charged). Among the 20 GCs, compounds with substitutions of halogen atoms or five-membered rings at C-17 achieved higher adsorption rates because of the enhanced formation of hydrogen bonds and a resulting increase in electron density. In addition, surrogate models with total fluorescence (TF) and ultraviolet absorbance at 254 nm (UV₂₅₄) were developed to monitor the attenuation trend of GCs during adsorption processes. Compared with the UV₂₅₄ model, the TF model showed better sensitivity to GC monitoring, which could greatly simplify the water quality monitoring process and facilitate online monitoring of GCs in water.