Rapid and sensitive smartphone non-enzymatic colorimetric assay for the detection of glucose in food based on peroxidase-like activity of Fe3O4@Au nanoparticles

Mo-doped carbon-dots nanozyme with peroxide-like activity for sensitive and selective smartphone-assisted colorimetric S2- ion detection and antibacterial application

Sulfur ion (S2-) plays a significant and considerable role in many living organisms and ecosystems, while its abnormal content can pose a serious hazard to human health and ecological environment. Hence, it is extremely meaningful to construct a highly sensitive and selective analytical platform for S2- detection in complex microenvironment, particularly in biological systems. In this study, phosphomolybdic acid and L-Arg were utilized to prepare a new molybdenum doped carbon-dots nanozyme (Mo-CDs) with great peroxidase-like activity by one-step hydrothermal approach. In the presence of H2O2, Mo-CDs converted 3,3',5,5'-tetramethyl benzidine (TMB) into blue oxTMB, but S2- strongly reduced the blue solution to colorless and then brown, which established significant selectivity toward S2-. Mo-CDs illustrated a wide linear range (2.5 μM-900 μM) and low detection limit (LOD = 76 nM) by ultraviolet and smartphone-assisted visualized colorimetric analysis. Especially, the smartphone-assisted analysis platform successfully realized quick, portable, sensitive and visible identification of S2- with high recovery (95.7-106.7 %) and excellent specificity in water samples. More importantly, Mo-CDs was developed to antibacterial applications based on good peroxidase-like activity. This research not only constructed a new and efficient carbon-dots nanozyme and a low-cost, portable, visual analysis platform for real-time detection of S2-, but also proposed a novel design strategy and methodology for exploiting multifunctional nanozyme detection tool with great practical application.

Development of Fe3O4/DEX/PDA@Au(Raman reporters)@Au-MPBA nanocomposites based multi-hotspot SERS probe for ultrasensitive, reliable, and quantitative detection of glucose in sweat

Glucose is a key biomarker of diabetes, and effective glucose monitoring methods are crucial to the prevention and management of diabetes. Therefore, in this paper, Fe3O4/DEX/PDA@Au (Raman reporters) @Au nanocomposites were synthetized that with DTNB (5,5'-dithiobis(2-nitrobenzoic)), MMTA (2-mercapto-4-methyl-5-thiazole acetic acid), MBA (4-mercaptobenzoic acid) and 4-Mpy(4-Mercaptopyridine) were used separately as Raman reporters. Fe3O4 and PDA (Polymerized dopamine) could supply more high surface area of active sites and high SERS (Surface-Enhanced Raman Scattering) substrate, which has high stability and reproducibility. Dextran coating is an effective way to prepare biocompatible materials TEM, XRD, TG and VSM were used to analyze the size, morphology and magnetic properties of the nanocomposites. Fe3O4/DEX/PDA@Au(Raman reporters)@Au that integrates a multi-hotspot structure and magnetic separation techniques were studied the enhancement effect of Raman spectra, and glucose solutions with different concentrations were tested. Furthermore, the optimal Fe3O4/DEX/PDA@Au(Raman reporters)@Au nanocomposites were supplied as SERS substrates for detection of glucose accurately and quickly in sweat. SERS signal intensity is linearly correlated with glucose concentration within the measurement range of 5 × 10-3 to 10 mM, and the minimum detectable concentration is 5 µM. The Fe3O4/DEX/PDA@Au(Raman reporters)@Au nanocomposites exhibit high reliability, specificity and repeatability of the strategy were then verified by practical detection of sweat.

Functionalizing of magnetic nanoparticles as nano-architecture towards bioimaging and colorimetric recognition of MCF-7 cells: dual opto-sensing and fluorescence monitoring for early-stage diagnosis of breast cancer

Considering the high incidence of breast cancer, a sensitive and specific approach is crucial for its early diagnosis and follow-up treatment. Folate receptors (FR), which are highly expressed on the epithelial tissue such as breast cancer cells (e.g., MCF-7), have been used in cancer diagnosis and bioimaging. This study presents an innovative colorimetric and fluorescence bioimaging platform towards MCF-7 using folic acid (FA)-conjugated iron-oxide magnetite silica-based nanocomposite (Fe3O4@SiO2-3-aminopropyl)triethoxysilane (APTES-NH2)@cysteine (Cyt)-Cyt@FA). For identification of MCF-7, the polyvinylpyrrolidone (PVP)-capped-platinum (Pt) nanoparticle was utilized as a nanozyme to catalyze the reaction between 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2 for visual detection of MCF-7 cells. Colorimetric changes are detectable by the naked eye and spectrophotometry at the wavelength of 450 nm, with a linear range of 50-5000 cells/mL and a detection limit of 30 cells/mL. The Fe3O4@SiO2-APTES-NH2@Cyt-Cyt@FA complex was modified with rhodamine B as a fluorescence bioimaging probe to monitor FR-overexpressed MCF-7 cells. The nanocomposite is biocompatible with a toxicity threshold of about 800 µg/mL. These methodologies facilitate bioimaging and colorimetric assays without sophisticated instrumentation, offering high specificity, sensitivity, repeatability, and stability, making them suitable as versatile methods for detecting and bioimaging cancer cells.

Green Synthesis of PtPdNiFeCu High-Entropy Alloy Nanoparticles for Glucose Detection

High-entropy alloys have long been used as a new type of alloy material and have attracted widespread concern because of their excellent performance, including their stable microstructure and particular catalytic properties. To design a safer preparation method, we report a novel approach targeting green synthesis, using tea polyphenols to prepare PtPdNiFeCu high-entropy alloy nanoparticles for glucose detection. The fabricated sensors were characterized by transmission electron microscopy and electrochemical experiments. Physical characterization showed that the nanoparticle has better dispersibility, and the average particle size is 7.5 nm. The electrochemical results showed that Tp-PtPdNiFeCu HEA-NPs had a high sensitivity of 1.264 μA mM-1 cm-2, a low detection limit of 4.503 μM, and a wide detection range of 0 - 10 mM. In addition, the sensor has better stability and selectivity for glucose detection.