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There is a growing interest in the use of flexible substrates for label-free and in situ Surface-enhanced Raman Spectroscopy (SERS) applications. In this study, a flexible SERS substrate was prepared using self-assembled Au/Ti3C2 nanocomposites deposited on a cellulose (CS) paper. The Au/Ti3C2 nanocomposites uniformly wrapped around the cellulose fibers to provide a three-dimensional plasma SERS platform. The limit of detection (LOD) of CS/Au/Ti3C2 was as low as 10−9 M for 4-mercaptobenzoic acid(4-MBA) and crystal violet (CV), demonstrating good SERS sensitivity. CS/Au/Ti3C2 was used for in situ SERS detection of thiram on apple surfaces by simple swabbing, and a limit of detection of 0.05 ppm of thiram was achieved. The results showed that CS/Au/Ti3C2 is a flexible SERS substrate that can be used for the detection of thiram on apple surfaces. These results demonstrate that CS/Au/Ti3C2 can be used for the non-destructive, rapid and sensitive detection of pesticides on fruit surfaces. [ABSTRACT FROM AUTHOR]

A multifunctional surface-enhanced Raman scattering (SERS) platform integrating sensitive detection and drug resistance analysis was developed for Gram-positive bacteria. The substrate was based on self-assembled Ti3C2Tx@Au NPs films and capture molecule phytic acid (IP6) to achieve specific capture of Gram-positive bacteria and different bacteria were analyzed by fingerprint signal. It had advantages of good stability and homogeneity (RSD = 8.88%). The detection limit (LOD) was 102 CFU/mL for Staphylococcus aureus and 103 CFU/mL for MRSA, respectively. A sandwich structure was formed on the capture substrate by signal labels prepared by antibiotics (penicillin G and vancomycin) and non-interference SERS probe molecules (4-mercaptobenzonitrile (2223 cm−1) and 2-amino-4-cyanopyridine (2240 cm−1)) to improve sensitivity. The LOD of Au NPs@4-MBN@PG to S. aureus and Au NPs@AMCP@Van to MRSA and S. aureus were all improved to 10 CFU/mL, with a wide dynamic linear range from 108 to 10 CFU/mL (R2 ≥ 0.992). The SERS platform can analyze the drug resistance of drug-resistant bacteria. Au NPs@4-MBN@PG was added to the substrate and captured MRSA to compare the SERS spectra of 4-MBN. The intensity inhomogeneity of 4-MBN at the same concentrations of MRSA and the nonlinearity at the different concentrations of MRSA revealed that MRSA was resistant to PG. Finally, the SERS platform achieved the determination of MRSA in blood. Therefore, this SERS platform has great significance for the determination and analysis of Gram-positive bacteria. [ABSTRACT FROM AUTHOR]

High performance platform for detecting ESBL-E. coil. [Display omitted] • Design of capture substrate to achieve stable, efficient capture of ESBL-E. coil. • Proposing of signal-enhancing structure and indirect method to detect ESBL-E. coil. • The platform has a good linear range and a detection limit of 10 CFU/mL. • A new method for the detection of ESBL-E. coil in milk. Drug-resistant bacteria is highly infectious and has been appearing in food in recent years threatening human health. Therefore, effective detection of drug-resistant bacteria is crucial. In this paper, an interference-free surface-enhanced Raman scattering (SERS) platform was developed for the detection of extended-spectrum β-lactamase E. coil (ESBL-E. coil). 4-mercaptomethylboronic acid (4-MPBA) was used as a capture molecule for drug-resistant bacteria, and self-assembled gold nanoparticles (Au NPs) were utilized to develop a high-performance SERS analytical platform for the detection of drug-resistant bacteria. Meanwhile, in order to obtain a lower detection limit and higher precision, Ti 3 C 2 T x , modified with 4-mercaptobenzonitrile (4-MBN) and Au NPs, was used for signal enhancement and indirect detection. The SERS platform detected signals from the Raman silent region, where there was no background signal from biological sources, eliminating the interference, a detection limit was 10 CFU/mL, with a wide dynamic linear range from 10-108 CFU/mL. Meanwhile, the stability, homogeneity and reproducibility were excellent. The precise quantification capability of the SERS platform was validated by the detection of ESBL-E. coil in milk. Therefore, the method holds great promise for the development of a stable and sensitive SERS platform for the detection of drug-resistant bacteria. [ABSTRACT FROM AUTHOR]

A novel composite material Nb 2 C-Au NPs can enhance electromagnetic resonance and charge transfer resonance by synergistic conjugation and exhibits good SERS enhancement of dye molecules and biomolecules adenine. [Display omitted] • Nb 2 C-Au NPs nanocomposite was synthesized by electrostatic self-assembly method. • Composite material can synergistically enhance multiple SERS mechanisms. • Nb 2 C-Au NPs exhibits good SERS detection performance for dye molecules and adenine. Recent years, two-dimensional transition metal carbonitrides (MXene) have attracted much attention in the field of surface-enhanced Raman scattering (SERS). However, the relatively low enhancement of MXene is a major challenge. Herein, Nb 2 C-Au NPs nanocomposites were prepared by electrostatic self-assembly method, which have a synergistically conjugated SERS effect. The EM hot spots of Nb 2 C-Au NPs are significantly enlarged and expanded, while the surface Fermi level is decreased. This synergistic effect could improve the SERS performance of the system. Consequently, for the dye molecules CV and MeB, the detection limits reach 10−10 M and 10−9 M, respectively, while for biomolecule adenine, the detection limit is as low as 5 × 10−8 M. The results also show the good concentration-dependent linearity, uniformity, reproducibility and stability of SERS substrate. Nb 2 C-Au NPs could be a fast, sensitive and stable SERS platform for label-free and non-destructive detection. This work may expand the application of MXene based materials in the field of SERS. [ABSTRACT FROM AUTHOR]