Miniaturized Thermal-Assisted Purge-and-Trap Technique Coupling with Surface-Enhanced Raman Scattering for Trace Analysis of Complex Samples

It still remains a great challenge for quantification of trace analytes in complex samples by surface-enhanced Raman scattering (SERS) technique due to potential matrix influence or weak SERS responses of analytes. In this work, a miniaturized thermal-assisted purge-and-trap (MTAPT) device was designed and developed to eliminate matrix influence coupled with derivatization method before SERS analysis. The design of MTAPT chamber was optimized based on quantitative calculation of its dead volume by computational fluid dynamics simulation. The small straight chamber was selected as an optimized design with a recovery of 96.1% for formaldehyde. The practical feasibility of MTAPT was validated based on four real analytical applications including phenthiol in industrial water, formaldehyde in flour, sulfion in wastewater, and methanol in industrial alcohol. The results showed that SERS responses of all analytes dramatically increased by eliminating sample matrices after MTAPT process. Phenthiol, formaldehyde, sulfion, and methanol in real samples could be accurately quantified with recoveries of 80.9–110.0%, and the analytical results were validated by corresponding standard methods. The time consumption of MTAPT-SERS for real sample analysis including sample preparation and determination was within 16 min. It is highly expected that the combination of MTAPT technique with portable SERS instrument can greatly expand the range of SERS analysis. The proposed MTAPT-SERS method has high potential for on-site analysis of complex samples

All-in-One Preparation Strategy Integrated in a Miniaturized Device for Fast Analyses of Biomarkers in Biofluids by Surface Enhanced Raman Scattering

Complex and tedious sample preparation processes have greatly limited rapid analyses of biological samples. In this work, an all-in-one sample preparation strategy based on a miniaturized gas membrane separation/oven ring enrichment (GMS/ORE) device was developed for efficient surface enhanced Raman scattering (SERS) analyses of trace biomarkers in biofluid samples. This strategy integrating gasification separation, liquid trapping, derivatization SERS activation, and coffee-ring enrichment could highly promote the efficiency of sample preparation. Meanwhile, the edges of membranes modified by the hydrophobic-infusing slippery liquid-induced uniform “coffee-ring” effect could significantly improve the sensitivity and stability for SERS quantification. By adapting proper derivatization approaches to the miniaturized GMS/ORE pretreatment, the matrix effects in samples could be prominently eliminated, and clear SERS responses could be obtained for the selective analyses of target biomarkers. The miniaturized GMS/ORE device was practically applied for SERS analyses of trace biomarkers in biofluids, including hydrogen sulfide in saliva samples, creatinine in serum samples, and sarcosine, creatinine, and dimethyl disulfide in urine samples. Accurate quantification of all biomarkers was achieved with recoveries of 89.5%–120.0%, and the contents found by GMS/ORE-SERS matched well with those found by corresponding chromatographic methods with relative errors from −8.6% to 9.3%. The miniaturized GMS/ORE device with multiple parallel processing units could simultaneously treat eight samples in one run with a total analysis time of 40 min. Such an efficient all-in-one strategy integrated on a miniaturized device possesses great potential for fast on-site/point-of-care detection in analytical science and clinical medicine

All-in-One Preparation Strategy Integrated in a Miniaturized Device for Fast Analyses of Biomarkers in Biofluids by Surface Enhanced Raman Scattering

Complex and tedious sample preparation processes have greatly limited rapid analyses of biological samples. In this work, an all-in-one sample preparation strategy based on a miniaturized gas membrane separation/oven ring enrichment (GMS/ORE) device was developed for efficient surface enhanced Raman scattering (SERS) analyses of trace biomarkers in biofluid samples. This strategy integrating gasification separation, liquid trapping, derivatization SERS activation, and coffee-ring enrichment could highly promote the efficiency of sample preparation. Meanwhile, the edges of membranes modified by the hydrophobic-infusing slippery liquid-induced uniform “coffee-ring” effect could significantly improve the sensitivity and stability for SERS quantification. By adapting proper derivatization approaches to the miniaturized GMS/ORE pretreatment, the matrix effects in samples could be prominently eliminated, and clear SERS responses could be obtained for the selective analyses of target biomarkers. The miniaturized GMS/ORE device was practically applied for SERS analyses of trace biomarkers in biofluids, including hydrogen sulfide in saliva samples, creatinine in serum samples, and sarcosine, creatinine, and dimethyl disulfide in urine samples. Accurate quantification of all biomarkers was achieved with recoveries of 89.5%–120.0%, and the contents found by GMS/ORE-SERS matched well with those found by corresponding chromatographic methods with relative errors from −8.6% to 9.3%. The miniaturized GMS/ORE device with multiple parallel processing units could simultaneously treat eight samples in one run with a total analysis time of 40 min. Such an efficient all-in-one strategy integrated on a miniaturized device possesses great potential for fast on-site/point-of-care detection in analytical science and clinical medicine

Photo-driven Surfactant-Free Gold Nanostars for Rapid Bacterial Detection in Food Safety Using Surface-Enhanced Raman Spectroscopy

Traditional foodborne bacterial detection methods have limitations, driving the need for advanced techniques like surface-enhanced Raman spectroscopy (SERS), known for its high sensitivity, specificity, and nondestructive analysis in food safety. However, SERS faces challenges regarding substrate sensitivity and complex sample preparation. This study presents an innovative photo-driven method for synthesizing surfactant-free anisotropic gold nanoparticles for SERS applications. These gold nanostars, with unique morphology and superior SERS performance, are used for sensitive Escherichia coli (E. coli) detection in complex food samples. Gold nanostar synthesis, controlled by the pH, reaction time, and HAuCl4 concentration, results in enhanced SERS capabilities. For in situ indole separation, a metabolic product of E. coli and the detection target, we introduce a miniaturized array gas membrane separation device. The SERS-based E. coli detection method exhibits remarkable sensitivity, with a 5 cfu/mL limit of detection and reliability within a 100–800 cfu/mL concentration range