High-Efficient Raman Enhancement on Organic Semiconductor-Stabilized Perovskite Heterostructures for Guiding Early Theranostics of Alzheimer's Disease.

Perovskites have recently emerged as attractive optoelectronic semiconductors due to tunable bandgap, large absorption coefficient, and long carrier lifetime, making it ideal as a kind of chemical-mechanism based surface-enhanced Raman scattering (SERS) substrates. However, perovskites generally demonstrate poor stability at ambient conditions, limiting their applications for SERS bioanalysis. Herein, we created a perovskite-based heterostructure through effectively passivating defects at the interface with hydrophobic organic semiconductors, which simultaneously enhanced the stability and efficiency of perovskite SERS substrate. The significant enhancement factor of 107 was mainly stemmed from the resonance Raman effect and the highly-efficient charge transfer process driven by a novel light-induced hot electron transfer mechanism in plasmon-free substrates previously never reported. This system was subsequently developed as an integrated theranostic SERS platform for miR-146a monitoring with a detection limit down to 0.2 fM, successfully guiding the early theranostics to enhance the therapeutic efficiency for Alzheimer's disease (AD). This work brings new light into the design of efficient and stable semiconductor SERS substrate and opens novel diagnosis and treatment options for AD.