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MicroRNA-21 is a potential cancer biomarker that is highly expressed in many cancer cells. Therefore, it is important to perform highly sensitive detection of miRNA-21. In this study, we designed a surface plasmon resonance imaging (SPRi) sensor based on an AuNPs/Ti3C2 composite for real-time and highly sensitive detection of miRNA-21. The fixation of the capture polyA-DNA probes was completed by the freezing method, which improved the detection efficiency. DNA−AuNPs/Ti3C2 conjugates were added to amplify the SPRi signal. The signal amplification combines the large specific surface area of Ti3C2 and the electronic coupling between the local surface plasmon resonance (LSPR) of AuNPs and the plasmon wave on the surface of the Au chip, thereby enhancing the SPRi response signal. Using this sensing strategy, the detection limit for miRNA-21 can reach 6.13 fM, with a wide dynamic range between 10 fM and 10 nM. In addition, the sensor has excellent selectivity for miRNA-21 and miRNAs with similar sequences, and receives minimal interference when applied to complex matrices. Based on these results, we believe that this study provides a simple and highly sensitive method for miRNA detection, which has great potential for the quantitative detection of miRNA in biomedical research and early clinical diagnosis. [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]