Polymerization of α-lipoic acid on silica particles and its Interfacial Engineering

Tissue adhesives have attracted significant attention as alternatives to conventional sutures and staples due to their ability to provide rapid sealing and minimize tissue damage. However, many existing systems still suffer from insufficient adhesion strength and limited adaptability to diverse biological surfaces. To overcome these limitations, nanoparticle-based strategies enabling precise surface modification have been increasingly explored. Among these, silica nanoparticles (SiNPs) offer an attractive platform due to their high surface area, chemical stability, and versatile surface chemistry.
α-Lipoic acid, a naturally occurring disulfide-containing molecule, has been widely studied in bio-inspired adhesive systems because it can generate thiol groups under reductive conditions and form dynamic interactions with various substrates. However, α-lipoic acid readily undergoes polymerization, while the resulting poly(α-lipoic acid) can rapidly depolymerize back into monomers, which limits its structural stability. To address this limitation, N-hydroxysuccinimide (NHS) functionalized molecules was introduced to stabilize the system by suppressing depolymerization, allowing poly(α-lipoic acid) to be maintained.
In this study, SiNPs with an average diameter of approximately 400 nm were functionalized with amine groups via silane chemistry and subsequently modified with NHS. Successful synthesis and surface modification were confirmed via FT-IR, DLS, and SEM analyses. FT-IR spectra verified the presence of functional groups corresponding to amine and amide bonds. DLS results showed a gradual increase in hydrodynamic diameter after each modification step, while SEM images confirmed uniform morphology without aggregation. We will further test adhesion performance of poly(α-lipoic acid) on surface of SiNPs using a universal testing machine. This study demonstrates an effective surface-functionalization strategy for enhancing adhesion in tissue adhesive systems, offering potential applications in biomedical adhesives and interfacial engineering