Jul 2026· Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy· Vol 363 Pt 1, pp.
128483
· 0 citations· 42 references
Medicine
TL;DR
A substrate-free dual-mode lateral flow immunoassay using intrinsically colored Prussian Blue nanoparticles (PB NPs) as multifunctional signal reporters is developed, providing a simple, rapid, and reliable approach for S. aureus detection with strong potential for point-of-care testing.
Abstract
Rapid identification of postoperative Staphylococcus aureus (S. aureus) infections is essential for timely treatment and improved clinical outcomes. Herein, we developed a substrate-free dual-mode lateral flow immunoassay (LFIA) using intrinsically colored Prussian Blue nanoparticles (PB NPs) as multifunctional signal reporters. The intrinsic blue color of PB NPs enables direct colorimetric visualization, while their excellent near-infrared photothermal conversion provides quantitative temperature readout. This self-signaling strategy eliminates enzymatic amplification and substrate incubation, simplifying the assay into a one-step sandwich immunoreaction. Under optimized conditions, the proposed LFIA achieved a wide linear detection range of 10-106 CFU/mL, with detection limits of 10 CFU/mL for the colorimetric mode and 1 CFU/mL for the photothermal mode. Analysis of real samples demonstrated good agreement with a commercial ELISA kit, with relative deviations below 10% and coefficients of variation below 15.5%, confirming the accuracy and practicality of the proposed platform. The dual-readout strategy improves analytical reliability through mutual signal verification, providing a simple, rapid, and reliable approach for S. aureus detection with strong potential for point-of-care testing.
A dual-mode colorimetric–photothermal LFIA platform was successfully constructed for the detection of thrombosis-related biomarkers, including thrombomodulin and α2-plasmin inhibitor–plasmin complex, in clinical serum samples, enhancing analytical sensitivity and reliability.
Jun Yin, Yu Qiu, Yao Nie et al.· RSC Advances· 0 citations
Foodborne infections and enterotoxin poisoning caused by S. aureus pose serious threats to food safety and public health. However, conventional detection methods are often time-consuming, technically complex, and typically require relatively large sample volumes. Herein, we report an aptamer-functionalized rough gold nanoparticle (RPG)-based photothermal platform that enables rapid and quantitative detection of S. aureus using a smartphone-compatible thermal imaging system in combination with a laser and an infrared thermal camera. RPGs were synthesized via a facile one-step method, and exhibited uniform particle size and a measured photothermal conversion efficiency of ~73.20%. After optimization of the aptamer concentration, laser irradiation time, and probe concentration, the proposed method exhibited a wide detection range from 1.0 × 102 to 1.0 × 107 cfu/mL, with an operational detection threshold of 100 CFU/mL under the optimized experimental conditions, a total assay time of less than 40 min, and a sample requirement of only 30 μL per assay, while maintaining acceptable reproducibility. Spike-and-recovery experiments in real samples, including orange juice, tap water, and milk, yielded recoveries of 91.8–105.5%, indicating suitable analytical performance in complex matrices. This work provides a rapid, portable, and low-sample-volume detection strategy for S. aureus, offering a practical approach for on-site food safety monitoring.
Rapid on-site detection of bacterial contamination remains an urgent need in public health and environmental monitoring. Herein, we report a one-step, label-free colorimetric sensor for broad-spectrum bacterial detection based on a competitive electrostatic mechanism. Cationic poly-l-lysine (PLL) induces the aggregation of anionic, citrate-capped gold nanoparticles (AuNPs), resulting in a distinct red-to-blue color change. In the presence of bacteria, their negatively charged surfaces adsorb PLL, thereby inhibiting AuNP aggregation and maintaining the red color of the dispersion. This strategy enables the visual detection of various Gram-positive and Gram-negative bacteria within 10 min. Using Escherichia coli (E. coli) as a model analyte, the assay reached a detection limit of 720 CFU/mL under the optimized conditions (5 μg/mL PLL, 3 min incubation, 20 mM phosphate buffer at pH 7.5) and exhibited a wide detection range from 102 to 107 CFU/mL (R2 > 0.99). The assay also performed reliably in spiked tap water and drinking water samples, with recoveries of 82-96% and CVs below 10%, demonstrating its potential as a rapid, low-cost screening tool for bacterial contamination in low-matrix water samples.
Herein, we propose a novel "low-background" biosensing platform integrating magnetic separation and hybridization chain reaction (HCR) for signal amplification, enabling ratiometric colorimetric detection and visual observation of S. typhimurium. In the presence of S. typhimurium, specific aptamer recognition triggers the HCR to couple the urease-labeled DNA to the HCR reporting system, ultimately generating a ratiometric colorimetric response upon enrichment by Fe3O4@PDA@PEI and magnetic separation. The assay demonstrates excellent sensitivity, achieving a detection limit of 2.34 CFU mL-1. Simultaneously, the ratiometric sensor enables direct visual detection of S. typhimurium at concentrations as low as 103 CFU mL-1. Furthermore, leveraging the photothermal properties of Fe3O4@PDA@PEI under 808 nm NIR irradiation significantly reduced S. typhimurium viability, thereby minimizing the risk of secondary contamination. Recovery rates of 84.2%-115.3% in common spiked food samples containing S. typhimurium confirm its practicality. This integrated "detection and inactivation" strategy offers a proactive defense for food safety.
Staphylococcus aureus (S. aureus) is a significant pathogen that causes foodborne diseases. Meat, with its abundant nutrients and high water activity, constitutes an ideal niche for S. aureus colonization. Numerous studies have shown that human digestive tract diseases caused by consuming meat products contaminated with S. aureus occur frequently. It is of great significance to strictly monitor S. aureus in meat matrices. A novel biosensor employing dual-signal output was developed through the combination of efficient magnetic separation and dual-modal precise detection. Designed for the rapid enrichment of S. aureus, it significantly boosts detection sensitivity and accuracy, thereby enabling the earlier identification of potential contamination sources. This method uses vancomycin-modified magnetic beads as the capture element, and aptamer-modified nanozymes as the signal element. After magnetic separation, the 3,3′,5,5′-tetramethylbenzidine color reaction can be used to quickly and sensitively detect S. aureus. It achieved a detection limit as low as 10 cfu/mL. Moreover, this dual-signal sensor based on efficient magnetic separation can sensitively detect S. aureus in meat products, thus showing good application prospects in food matrices and further improving the reliability and specificity of detection.
A dual-aptamer-based, dual-mode FRET lateral flow strip is developed for the rapid and sensitive detection of thrombin in serum samples, achieving a fluorescence-based detection limit of 0.135 nM-twice as sensitive as the colorimetric method.