3-mercaptopropyltrimethoxysilane as insulating coating and surface for protein immobilization for piezoelectric microcantilever sensors

Abstract

We have examined coating (PbMg(13)Nb(23)O(3))(0.63)-(PbTiO(3))(0.37) (PMN-PT)/tin and lead zirconate titanate (PZT)/glass piezoelectric microcantilever sensor (PEMS) with 3-mercaptopropyl-trimethoxysilane (MPS) by a simple solution method to electrically insulate the PEMS for in-water applications. In contrast to earlier methytrimethoxysilane insulation coating, the MPS coating also facilitated receptor immobilization on the sensor surface via bonding of its sulhydryl group to a bifunctional linker, sulfosuccinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate. We showed that a MPS coating of 21 nm in thickness is sufficient to electrically insulate and provide immobilization surface to the PEMS for in-liquid electrical self-excitation and self-sensing. The in-phosphate buffered saline solution resonance spectra were stable with Q values ranging from 41 to 55. The mass detection sensitivities were determined to be 5x10(-11) and 8x10(-12) gHz for the MPS-insulated PZT-glass and PMN-PT/tin PEMSs, respectively.

Array lead zirconate titanate/glass piezoelectric microcantilevers for real-time detection of Bacillus anthracis with 10 spores/ml sensitivity and 1/1000 selectivity in bacterial mixtures

“…2 the in-air and in-water resonance spectra of a PZT/glass PEMS electrically insulated by a 3-mercaptopropyltrimethoxysilane ͑MPS͒ coating. 23 As can be seen from Fig. 2, the in-water resonance frequency and resonance peak width of the longitudinal mode and those of the width mode remained close to those of the in-air spectrum.…”

“…From our earlier studies, a typical saturation time ranges from a few minutes at higher concentrations, e.g., 10 5 spores/ ml to 15-30 min at lower concentrations, e.g., 10 1 spores/ ml. [20][21][22][23]26 The present detection scheme allowed us to detect BA over a wide range of concentrations, 10 1 -10 7 spores/ ml over a short time. While these experiments did not yield a linear dose response of the PEMS to these concentrations of BA, which would require preparing the sensor surface after detection at each concentration, they nonetheless amply demonstrated the "repeatability" of the detection from sensor to sensor, which is one of the main goals of this study.…”

“…The anti-BA antibody was immobilized on the MPS insulation coating of PEMS by means of a bifunctional linker, sulfosuccinimidyl-4-͑N-maleimidomethyl͒cyclohexane-1-carboxylate ͑sulfo-smcc͒ as described in Ref. 23.…”

“…Real-time, label-free antigen detection is achieved by electrically monitoring the PEMS flexural resonance frequency shift. [19][20][21][22][23][24][25][26] PEMS flexural-mode detection sensitivity is related to the thickness and the size of the PEMS. Generally, a PEMS flexural-mode detection sensitivity increases with a reduced PEMS size and thickness.…”

Label-free, all-electrical, in situ human epidermal growth receptor 2 detection

“…Direct, label-free detection is achieved by monitoring the PEMS resonance frequency shift in real time. [8][9][10][11][12][13] In a previous study, we have demonstrated that 3-mercaptopropyltrimethoxysilane ͑MPS͒ can be used to coat a PEMS and serve both as an electrically insulating layer and as a substrate for immobilization of antibodies. The goal of this study was to investigate MPS-insulated PEMS for direct, rapid, label-free, in situ detection of Her2 at clinically relevant concentrations in mixed protein solutions.…”