Biotinylated Silatrane: Development Functional Organosilicon Biointerfaces for Molecular Detection

Biotin-avidin ligation represents the strongest known noncovalent protein-ligand interaction, serving as a cornerstone for high-affinity biosensing. However, the inherent tendency of biotin to promote nonspecific adsorption often compromises the sensitivity and reproducibility of such platforms. Silatranes have emerged as superior building blocks for surface functionalization of such biosensing platforms, offering enhanced hydrolytic stability, processability, and tunable silanization kinetics mediated by the internal transannular N→Si dative bond. In this work, we report the first synthesis of a biotinylated silatrane via azide-alkyne cycloaddition. The molecular structure was characterized using ¹H NMR, FT-IR, and mass spectrometry. To develop a multifunctional biointerface, biotinylated silatrane was co-deposited with a zwitterionic sulfobetaine silatrane, creating a dual functional coating that integrates specific molecular recognition with potent antifouling properties. Surface characterization via water contact angle (WCA) goniometry, spectroscopic ellipsometry, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) confirmed the formation of highly hydrophilic, uniform, and stable organosilicon adlayers. The specificity of the platform was validated through avidin bioconjugation, where quartz crystal microbalance with dissipation (QCM-D) and interfacial analysis confirmed the formation of a stable, well-ordered avidin layer. Finally, the biotinylated silatrane-based architecture was successfully employed for the detection of cancer biomarker carcinoembryonic antigen (CEA), demonstrating a linear response at clinically relevant concentrations. The findings establish biotinylated silatrane as a robust and versatile building block for the development of high-performance and fouling-resistant biointerfaces in diagnostic technologies and biosensing platforms.