SERS active silk silver films as a platform for osteogenic biomarker detection

Abstract

Surface-enhanced Raman scattering (SERS) is a powerful analytical technique for molecular detection, offering high sensitivity and label-free identification. However, achieving reproducible and highly efficient SERS substrates remains a challenge. In this study, we developed a silver nanoparticle (AgNP)-embedded silk fibroin film as a multifunctional SERS platform. An in situ light-mediated reduction method was employed to synthesize AgNPs within a silk fibroin matrix, ensuring uniform nanoparticle distribution and strong plasmonic activity. Silver nanoclusters were observed to be formed in the silk matrix at lower concentrations of silver nitrate in silk fibroin solution. These nanoclusters acted as hotspots for SERS activity of the formed films and for the detection of protein biomarkers. The biocompatibility, optical properties, and wettability of the silk silver films were systematically characterized, demonstrating their potential for biosensing applications. Notably, the integration of AgNPs within the silk film enhanced SERS signals due to strong plasmonic coupling and nanoparticle-matrix interactions. To explore their biomedical utility, specifically in tissue engineering, where it is important to achieve temporal control over biomolecules for manipulating cell growth, proliferation and differentiation, we evaluated the platform for the detection of bone morphogenetic protein-2 (BMP-2), a critical biomarker in osteogenesis and cancer diagnostics. The silk silver films exhibited ultrasensitive and specific SERS responses, enabling the detection of BMP-2 at low concentrations. The synergy between the plasmonic properties of AgNPs and the biocompatibility of silk provides a versatile and tunable platform for biosensing, particularly in disease diagnostics and biomedical applications. This study highlights the potential of silk silver films as next-generation SERS substrates for early biomarker detection in real time for advancing tissue engineering applications.