Comparative Silane Surface Functionalization Strategies for Enhanced Bloch Surface Wave Biosensing of Anti-SARS-CoV-2 Antibodies

TL;DR

This study compares three silane surface chemistries for biosensing of SARS-CoV-2 antibodies using Bloch surface wave sensors, identifying CPTES as the most effective for rapid, sensitive antibody detection.

Contribution

It provides a standardized evaluation of silane chemistries for BSW biosensors, highlighting CPTES as the optimal surface functionalization for SARS-CoV-2 antibody detection.

Findings

CPTES showed the best balance of signal specificity and low nonspecific adsorption.

All three chemistries enabled effective fluorescence detection of antibodies.

The platform demonstrated rapid and sensitive serological analysis.

Abstract

Surface functionalization plays a decisive role in the performance of biosensors, as it governs the efficiency and stability of biomolecule immobilization at the sensor interface and, consequently, the overall performance of the biosensing platforms. In this work, we present a comparative study of three organosilane chemistries - APTES, APDMS, and CPTES - applied to a SiO2 terminated 1D photonic crystal able to sustain Bloch surface waves and designed to operate as optical biosensors in both label free and fluorescence enhanced modes. Each chemistry was evaluated through a standardized label-free protocol based on the interaction between immobilized SARS CoV 2 spike protein and its corresponding antibodies, enabling quantitative assessment of binding efficiency, nonspecific adsorption, and signal repeatability. CPTES exhibited the most favorable balance between specific signals, reduced variability, and low nonspecific adsorption. The three chemistries were subsequently tested in fluorescence mode for the detection of anti SARS CoV 2 IgG antibodies in human serum, demonstrating the suitability of BSW enhanced fluorescence for rapid serological analysis. Overall, the study identifies CPTES as the most robust and reproducible functionalization strategy among the three investigated for BSW biosensing and highlights the potential of the platform for fast, sensitive detection of clinically relevant antibodies.