The development of straightforward and cost-efficient methods for bacterial identification is very important. In this study, we utilized xylenol orange, metal ions, and diverse bacterial carbon sources to construct a sensor array, achieving precise bacterial identification. Initially, we examined the absorbance variations of xylenol orange with five metal ions (Mn2+, Co2+, Ni2+, Cu2+, and Zn2+) at pH levels ranging from 4 to 7, observing significant changes at 570 nm or 580 nm. Given that bacteria can generate varying amounts of acid in different carbon sources, we employed a blend of xylenol orange and the five metal ions as pH-sensitive probes to characterize bacterial metabolism in three carbon sources, resulting in the development of a five-sensor array that effectively differentiated seven bacteria. Additionally, by utilizing xylenol orange with Co2+, we successfully identified six different bacterial mixtures and five types of probiotic drink products. These findings highlight the potential of our methods for broader practical application in bacterial identification in practical use.
Low efficacy and frequent use of conventional pesticide formulations have led to various food safety and ecological concerns. Green and effective nanoformulation offers promising solutions to water-insoluble pesticides. Herein, we prepared a water-based nanoparticulate formulation of lambda-cyhalothrin (LC WBNF) using high-gravity rotating packed bed (RPB) combined with lyophilization. The prepared formulation could be dispersed in water with an average particle size of 54.5 ± 0.7 nm and maintained long-term stability. LC WBNF demonstrated significant improvement in foliar wettability, adhesion, and resistance to rain-induced washout. LC WBNF enhanced the uptake and translocation of LC in broad bean plants due to the presence of nanoparticles. Furthermore, the insecticidal activity of LC WBNF was 2.8 and 2.3 times higher than that of commercial LC WP and LC WDG, respectively. This study presents a novel strategy for the development of nanoinsecticides for practical application in agricultural production.
This study presents a dual-band terahertz metasurface biosensor based on the electromagnetically induced transparency (EIT) effect. The sensor employs copper resonant rings and a quartz dielectric substrate, enabling switching between single and dual-EIT (D-EIT) modes by altering the polarization direction of incident terahertz waves. The physical mechanism of the dual-EIT effect was elucidated through electric field analysis, revealing bright-dark mode coupling (0.53 THz) and bright-bright mode coupling (0.76 THz). Simulations demonstrated a refractive index sensitivity of up to 220 GHz/RIU. Experimentally, the metasurfacel fabricated via laser engraving exhibited dual-frequency sensing capabilities for lactose and chlortetracycline hydrochloride, with a minimum detectable concentration of 0.1 mg/L in both aqueous and milk solutions. Despite limitations in low-concentration detection within complex media due to increased optical loss, this sensor shows significant potential for applications in food safety and antibiotic residue monitoring.
Fang Wang,Yi-Mei Li,Jing Zhao,Jing Ye,Yuan-Ting Li
This study presents a dual-mode colorimetric and surface enhanced Raman scattering (SERS) platform for the highly sensitive and selective assay of N-nitrosodiethylamine (NDEA) in antihypertensive drugs. A polydopamine embedded molecularly-imprinted agarose hydrogel (MIAG) chip was developed, serving as a multifunctional sensing substrate. Upon exposure to NDEA, the chip facilitates specific target adsorption and enrichment, simultaneously triggering a Griess reaction that yields a deep-red azo compound. This reaction provides the basis for both colorimetric readout and generates a strong Raman signal through azo-enhanced scattering for quantification. This design allows the MIAG chip to function not only as a naked-eye indicator but also as a platform for smartphone-based colorimetric analysis by directly translating color responses into digital barcodes. Furthermore, the in-situ synthesized gold nanoparticles (AuNPs) within the hydrogel matrix generate enhanced SERS activity, leveraging the porous network to create abundant hotspots for ultra-sensitive detection, achieving a limit of detection as low as 2.3 × 10 −14 M. The synergistic combination of dual-mode output offers robust and cross-verification results, significantly improving detection reliability. This integrated smartphone-compatible platform holds great promise for point-of-care testing of drug safety, making accurate screening accessible from regulatory laboratories to the public
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