An effective strategy for aminosilane functionalization on dielectric surfaces in advanced biosensing applications
Journal
Sensors and Actuators B: Chemical
Journal Volume
450
ISSN
0925-4005
Date Issued
2026-03
Author(s)
Abstract
Aminosilane is commonly employed as a crosslinker in biosensors due to its dual-functional properties for bio-conjugate bindings. Although current researches on aminosilane-modification strategies have predominantly focused on adjusting deposition parameters, the charge state of the amino groups has been overlooked. This parameter critically affects the self-catalytic hydrolysis of silane and the stability of surface linkers. To address this gap, we investigated the interplay between aminosilane protonation and hydrolysis. Based on our findings, a novel modification strategy was proposed. In brief, we developed a surface-charge sensor to monitor the transient charge state of aminosilane in a real time manner. Utilizing the developed sensor, we demonstrated that (3-Aminopropyl)triethoxysilane (APTES) and N-(2-Aminoethyl)-3-aminopropyltriethoxysilane (AEAPTES) undergo deprotonation during the curing step. These deprotonated linkers subsequently experience significant hydrolysis in deionized water environments. Compared with APTES, AEAPTES showed better stability but still exhibited a 20.7 % variation in sensing signal. Atomic force microscopy (AFM) analysis confirmed this instability, revealing an average roughness change of 97(5) pm. Given the hydrolysis susceptibility of the deprotonated surface, we proposed incorporating a surface protonation step by immersing the substrate in a 1X PBS solution. This modification led to a 21 % improvement in sensing signal stability of AEAPTES, with AFM analysis revealing only a 5(1) pm roughness change under hydrolytic conditions. The resulting silane layer was 10.57 % rougher than that obtained with the non-modified approach. Additionally, fluorescence analysis further confirmed a 13.87 % increase in immobilization efficiency. These results highlight the importance of modifying the charge state in improving modification processes.
Subjects
AEAPTES
AFM
Aminosilane
APTES
Fluorescein
Modification strategy
Non-faradaic biosensor
Surface charge
Publisher
Elsevier BV
Type
journal article