Dual-Modulation of Charge Transfer in Surface-Enhanced Raman Scattering for Qualitative and Quantitative Exosome...

The practical application of chemical-mechanism-based surface-enhanced Raman scattering (SERS) is often limited by the static charge-transfer process in conventional semiconductor substrates. Herein, we propose a multifunctional photoelectric platform that enables dynamic dual-modulation of the photoinduced charge transfer (PICT) process for ultrasensitive SERS bioanalysis. Upon mechanical stimulation, the polyvinylidene fluoride (PVDF) matrix generates a built-in electric field, which effectively lowers the excitation barrier and further promotes the PICT efficiency, thereby exhibiting an enhancement factor (EF) with nearly 10-fold improvement under a pressure of only 3 N. Beyond piezoelectric regulation, the NaGdF4@Au nanoprobes, under near-infrared excitation, produce an anti-Stokes emission that overlaps with the vibronic bands of the tagged 4-mercaptopyridine (4-Mpy). Benefiting from this cooperative piezoelectric-photonic mechanism, our platform achieves ultrasensitive detection as low as 40 particles/mL while enabling highly accurate classification (≥98%) of cancer-derived exosomes. This work paves a promising way for developing regulated SERS platforms with broad potential for diverse bioanalytical applications beyond cancer-derived exosome detection.