The combination of microfluidic technology and surface-enhanced Raman spectroscopy (SERS) has the advantages of being label-free, fingerprint spectroscopy, and high sensitivity, which giving the combination great potential for rapid trace-level biological and environmental analysis. In this review, we summarized the recent progress in these two fields, e.g., microfluidics and SERS, including the basic strategies of a simple and versatile microfluidic-SERS detection system and its wide-ranging applications. Moreover, we listed the main challenges and future directions of the microfluidic-SERS systems; proposed on-chip applications beyond SERS; developed a more efficient, more sensitive, and more convenient microfluidic-SERS system; and formed a more complete on-site real-time detection technology.

Metal–organic framework (MOF) compounds are centered on metal ions or metal ion clusters, forming lattices with a highly ordered periodic porous network structure by connecting organic ligands. As MOFs have the advantages of high porosity, large specific surface area, controllable pore size, etc., they are widely used in gas storage, catalysis, adsorption, separation and other fields. SERS substrate based on MOFs can not only improve the sensitivity of SERS analysis but also solve the problem of easy aggregation of substrate nanoparticles. By combining MOFs with SERS, SERS performance is further improved, and tremendous research progress has been made in recent years. In this review, three methods of preparing MOF-based SERS substrates are introduced, and the latest applications of MOF-based SERS substrates in biosensors, the environment, gases and medical treatments are discussed. Finally, the current status and prospects of MOF-based SERS analysis are summarized.

Nucleic acid aptamers are single-stranded oligonucleotides that are selected through exponential enrichment (SELEX) technology from synthetic DNA/RNA libraries. These aptamers can specifically recognize and bind to target molecules, serving as specific recognition elements. Surface-enhanced Raman scattering (SERS) spectroscopy is an ultra-sensitive, non-destructive analytical technique that can rapidly acquire the “fingerprint information” of the measured molecules. It has been widely applied in qualitative and trace analysis across various fields, including food safety, environmental monitoring, and biomedical applications. Small molecules, such as toxins, antibiotics, and pesticides, have significant biological effects and are harmful to both human health and the environment. In this paper, we mainly introduced the application and the research progress of SERS detection with aptamers (aptamer-based SERS techniques) in the field of small-molecule detection, particularly in the analysis of pesticide (animal) residues, antibiotics, and toxins. And the progress and prospect of combining the two methods in detection were reviewed.

The detection of bifenthrin is closely related to the adsorption of SERS substrates. In this study, superparamagnetic Fe₃O₄@Au MNPs coated with GO were used to detect the adsorption and enrichment of bifenthrin molecules with benzene rings. Firstly, the thermal solvent method synthesized Fe₃O₄ magnetic nanoparticles (MNPs) with a particle size of ~250 nm. Next, polyethylene imide (PEI) was used as an intermediate layer to modify the surface of Fe₃O₄ to form a positively charged ultra-thin polymer middle layer. Next, the gold shell was developed by adsorption of ~20 nm AuNPs, without affecting the magnetic properties. Then, the additional amount of colloidal gold and GO on SERS performance was systematically studied. Using crystal violet (CV) as the probe, we investigated the SERS performance of composite nanomaterials. The lowest detected concentration reached 10⁻⁸ mol/L, confirming that the composite functional material had good SERS activity and magnetic properties. Finally, the substrate was used to detect bifenthrin in an acetone solution, and the lowest detection concentration was 10⁻⁸ mol/L. These results showed that the prepared GO/Fe₃O₄@Au MNPs were efficient SERS substrates that could detect bifenthrin pesticide residue with high sensitivity.