Toward Universal SERS Detection of Disease Signaling Bioanalytes Using 3D Self-Assembled Nonplasmonic...

Currently, the quantum-scale surface-enhanced Raman scattering (SERS) properties of Si materials have yet to be discovered for universal biosensing applications. In this study, a potential universal biosensing probe is generated by activating the SERS functionality of Si nanostructures through near quantum-scale (nQS) engineering. We introduce herein 3D nonplasmonic Si nanomesh structure with nQS defects for SERS biosensing applications. Through ionization of a single-crystal defect-free Si wafer, highly defect-rich Si subnano-orbs (sNOs) are fabricated and self-assemble as connective 3D Si nanomesh structures with enhanced SERS biosensing activity. By amending the laser ionization and ion-ion interactions, we observe the controlled synthesis of engineered nQS defects in the form of nQS-grain boundary disorder or surface nQS voids within the interconnected Si sNOs. To our knowledge, it is shown here for the first time that defect-rich Si nanomesh structures exhibit enhanced Raman activity, with the nQS morphological and crystallographic defects acting as the prime SERS contributors without a plasmonic contribution. The SERS biosensing sensitivity with the synthesized defect-rich Si nanomesh structures without an additional plasmonic material was evaluated using of a tripeptide biomarker l-glutathione (GSH); we observe an enhancement factor value of ∼10² for the GSH biomolecules with 10^-9 M sensitivity, a phenomena to our knowledge that has yet to be reported. Additionally, the SERS detection of multiple disease-signaling biomolecules (cysteine, tryptophan, and methionine) is achieved at very low analyte concentration (10^-9 M). These results indicate a potential new dimension to universal SERS biosensing applications with these unique nonplasmonic defect-rich 3D nQS-Si nanostructures.