Stimuli-responsive SERS biosensor for ultrasensitive tetracycline sensing using EDTA-driven PEI@CaCO3 microcapsule and CS@FeMMs

In this work, a stimuli-responsive SERS biosensor was fabricated for tetracycline (TTC) by “signal-on” strategy using (EDTA)-driven polyethyleneimine grafted calcium carbonate ( [email protected] 3 ) microcapsule and chitosan-Fe magnetic microbeads ( [email protected] ). Initially, aptamer conjugated magnetic-bead [email protected] @Apt with superparamagnetism and excellent biocompatibility was employed as capture probe, which facilitated the rapid and easy magnetic separation. Subsequently, the PEI cross-linked layer and aptamer network layer were constructed onto the outer layer of CaCO 3 @4-ATP microcapsule to form sensing probes ( [email protected] 3 @ [email protected] ) via the layer-by-layer assembly method. In the presence of TTC, a sandwich SERS-assay was exploited by aptamer recognition induced target-bridged strategy. When the solution of EDTA was added, the core layer of CaCO 3 would be dissolved quickly, destroying the microcapsule to release 4-ATP. The released 4-ATP could be quantitatively monitored by dripping the supernatant onto the [email protected] SERS platform, resulting in a strong Raman “signal-on”. Under the optimal conditions, a good linear relationship was established with a correlation coefficient ( R 2 ) of 0.9938 and a LOD of 0.03 ng/mL. Additionally, the application capacity of the biosensor to detect TTC was also affirmed in food matrixes, and the results were consistent with the standard ELISA method ( P  > 0.05). Hence, this SERS biosensor affords extensive application prospects for TTC detection with multiple merits such as high sensitivity, environment friendliness, and high stability.