Investigation of 3-Mercaptopropylmethoxysilane Based Coating Methods for Biosensor Applications

Currently, controlling the coating quality of 3-Mercaptopropyltrimethoxysilane (MPS) which is preferred as a functional coating agent for biodetection is not straightforward. The pH must be precisely adjusted to improve the coating quality. At the same time, in order to be able to make a precise measurement, systems which are real time, fast and not affected from the environment are needed. In this study, Quartz Crystal Microbalance (QCM) sensor was used to determine and analyze the best coating method based on MPS. The sensor surface was coated in two different ways: Coating-I and Coating-II. Coating-I is solely based on MPS and the surface was coated with acidic and basic solutions of MPS, respectively. In Coating-II, the surface was modified with MPS firstly and then 2-Mercaptoethanol (ME) solutions. The surface modification was controlled with introducing Bovine Serum Albumin (BSA) suspension to the system. While inverse frequency shift was observed in Coating-I and surface coating did not occur, in Coating-II an average 200 Hz frequency shift was observed at each step and the surface was coated. This surface coating provides a real-time, fast and convenient surface chemistry for sensors of interest.