Preparation Of Core-shell Structure Nanoparticles And Its Application In Exosome Detection

Surface enhanced Raman scattering(SERS)technology has the advantages of rich spectral information,strong accuracy,and high sensitivity.It is widely used for the detection and analysis in the fields of biomedicine,food safety,and environmental monitoring.Up to now,various of SERS probes have been demonstrated.Among these,core-shell structure-based SERS nanoprobes have attacted much attention due to their ability to significantly enhance the local electromagnetic field,which have a great potential in the field of biological sensing.Exosomes are vesicles with a size of 30-150 nm,which are considered to be a potential biomarker of many diseases.The detection of exosomes has important guiding significance in the diagnosis and treatment of various diseases including cancer.This paper proposes an exosomal detection method based on SERS probes with a built-in nano-gap and magnetic nanoparticles with a core-shell structure.In the experiments,first,the core-shell structured SERS nanoprobes with built-in nano-gap was prepared and their structural properties and SERS characteristics were studied.To achieve the best enhancement effect,the influencing factors on SERS enhancement effect of the probe were analyzed in detail.Second,a magnetic nanoparticle probe was prepared for capturing exosomes using the aptamer-conjugated surfaces.Finally,based on the sandwich immunodetection scheme,the SERS probe functionalized with aptamers was used to achieve the detection of human breast cancer cellular exosome with a limit of detection(LOD)as 5x10~4/m L.In such a kind of SERS probe,Raman reporter is located inside the gap between Au and Ag shell,which can increase the stability of SERS signal in a complex physiological environment.On the other hand,it can effectively avoid the competition between the aptamer and Raman reporter on the surfaces of probes,thereby improving the accuracy and reliability of the detection.