SERS Sensors Based on Aptamer-Gated Mesoporous Silica Nanoparticles for Quantitative Detection of Staphylococcus aureus with Signal Molecular Release

This work describes a simple and novel biosensor for the quantitative determination of Staphylococcus aureus (S. aureus) based on target-induced release of signal molecules from aptamer-gated aminated mesoporous silica nanoparticles (MSNs) coupled with surface-enhanced Raman scattering (SERS) technology. MSNs were synthesized and then modified with amino groups by (3-aminopropyl) triethoxysilane to make them positively charged. Next, signal molecules (4-aminothiophenol, 4-ATP) were loaded into the pores of MSNs. Then, negatively charged aptamers of S. aureus were assembled on the surface of MSNs through electrostatic interactions. Upon the addition of S. aureus, the assembled aptamers were specifically bound to the bacteria. Consequently, the gates were opened, resulting in the release of 4-ATP from the pores of MSNs. The released molecules were measured by a Raman spectrometer, and the intensity of 4-ATP at 1071 cm(-1) was linearly related to the S. aureus concentration. A silver nanoflower silica core-shell structure (Ag NFs@SiO2) was prepared and it served as a SERS substrate. Under optimized experimental conditions, a good linear relationship (y = 2107.93 + 1536.30x, R-2 = 0.9956) in the range from 4.7 x 10 to 4.7 X 10(8) cfu/mL was observed with a limit of detection of 17 cfu/mL. The method was successfully applied for the analysis of S. aureus in fish samples and the recovery rate was 91.3-109%.

Automated summary

This work presents a simple and novel biosensor for the quantitative determination of Staphylococcus aureus using aptamer-gated aminated mesoporous silica nanoparticles and surface-enhanced Raman scattering technology. The method showed a good linear relationship in the detection range, with a limit of detection of 17 cfu/mL, and was successfully applied in fish samples with a high recovery rate of 91.3-109%.