Synergistic Electromagnetic and Chemical Enhancement via Carbon Quantum Dot-Functionalized Triangular Silver Nanoplates on Nano-Mica Platelets for Ultrasensitive SERS Biosensing

We report a high-performance ternary nanohybrid for surface-enhanced Raman scattering (SERS) biosensing that integrates sharp-tipped triangular silver nanoplates (TAgNPs) with two-dimensional (2D) exfoliated nano-mica platelets (NMPs) and carbon quantum dots (CQDs). TAgNPs were synthesized via a seed-mediated route and uniformly deposited onto the NMP surface, forming stable TAgNPs/NMPs nanohybrids that enabled a three-dimensional (3D) distribution of electromagnetic hot spots. CQDs were prepared hydrothermally using glucose and reduced glutathione as precursors and subsequently anchored onto the TAgNPs/NMPs surface. This interfacial modification improves energy-level alignment and promotes charge-transfer (CT) contributions, yielding TAgNPs/NMPs/CQDs nanohybrids. For adenine detection, the nanohybrids achieved a limit of detection (LoD) of 10-9 M and an enhancement factor of 9.3 × 108, with high signal uniformity (relative standard deviation, RSD = 7.4%). For Staphylococcus aureus sensing, the platform reached an LoD of 10 CFU mL-1 and showed good reproducibility (RSD = 9.2%). Collectively, these results establish a scalable scaffold-stabilization and interface-functionalization co-design strategy for SERS substrates. Exfoliated NMPs act as a programmable 2D support that localizes and stabilizes near-field hot spots, enabling hierarchical 3D architectures. CQDs provide precise interfacial modulation and introduce CT-mediated pathways that enhance molecular capture and signal transduction. The resulting platform supports rapid pathogen screening and offers a generalizable materials blueprint for translational SERS biosensing.