Abstract
A biocompatible and functional interface can improve the sensitivity of bioelectronics. Here, 3-aminopropyl trimethoxysilane (APTMS) and 3-mercaptopropyl trimethoxysilane (MPTMS) self-assembled monolayers (SAMs) were independently modified on the surface of silicon nanowire metal-oxide-semiconductor field effect transistors (NW-MOSFETs). Those SAMs-modified silicon NW-MOSFETs were used to discriminate various pH solutions and further verify which modified regime was capable of providing better electrical signals. The APTMS-SAM modified NW-MOSFETs showed better electrical responses in pH sensing. Biomolecules on APTMS-SAM modified NW-MOSFETs also gave better signals for the corresponding proteind in physiological buffer solutions. Atomic force microscopy (AFM) clarified those electrical phenomena and found biomolecules on APTMS-SAM were relatively uniformly modified on NW-MOSFETs. Our results showed that more uniform modification contributed to better signal response to protein interactions in physiological buffer solutions. It suggests that suitable surface modifications could profoundly affect the sensing response and sensitivity.
Highlights
Metal-oxide-semiconductor field-effect transistors (MOSFETs) have been developed by using advanced micro- and nano-electro-mechanical systems (M/NEMS) technology [1,2,3]
The biointerface was created by immersing aminopropyl trimethoxysilane (APTMS) or mercaptopropyl trimethoxysilane (MPTMS) modified NW-MOSFETs in 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) citrate buffered solution of antibody against prostate-specific antigen
Electrical measurement was used to verify that the varied functional groups pre- and postfunctionalization would have great impact on the sensing response and sensitivity of NW-MOSFETs in our study
Summary
Metal-oxide-semiconductor field-effect transistors (MOSFETs) have been developed by using advanced micro- and nano-electro-mechanical systems (M/NEMS) technology [1,2,3]. Silanization is the most applied method of modifying silicon oxide by creating a uniform self-assembled monolayer (SAM) of silanol groups, which can further conjugate biomolecules to form a functional biointerface. This biointerface with tunable biocompatibility can contribute better electrical signals to specific detection problems. There have been lots of studies that have exploited the functional biointerfaces on silicon NW-FET for many biological tests, such as protein interactions [2,4,8] and specific antigen-antibody reactions [5,6,18]. Various studies have tackled surface modification of silicon NW, the comparison of the effect of variously modified SAM molecules on sensing signals is seldom addressed. The appearance of each step of the modification and immobilization process was scanned by AFM and matched to the results of electrical measurement in pH tests and detection of various concentrations of biomolecules
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