Magnetic–Optical Core–Shell Nanostructures for Highly Selective Photoelectrochemical Aptasensing

Selectivity is a crucial parameter for photoelectrochemical (PEC) sensing in a practical setting. Despite the use of specific probes such as aptamers, antibodies, and enzymes, coexisting interferences can still result in inaccuracies in PEC sensing, especially for complex biosample matrixes. Here we report the design of an Fe 3 O 4 @SiO 2 @TiO 2 magnetic–optical bifunctional beacon applied in a novel PEC sensor that can selectively capture progesterone in complex biosamples, be magnetically separated and cleaned, and be detected in pure phosphate buffer solution (PBS). The magnetic separation strategy efficiently removes the complex coexisting species from the modified electrode surface and drastically enhances the selectivity of the as-designed PEC sensor. The as-designed PEC sensor is cost-effective, easy to fabricate, highly selective and sensitive, and highly reliable, making it a promising platform for efficient aptasensing.