Optimization of 3-aminopropyltriethoxysilane functionalization on silicon nitride surface for biomolecule immobilization

Pawasuth Saengdee; Chamras Promptmas; Surachoke Thanapitak; Awirut Srisuwan; Apirak Pankiew; Nutthaphat Thornyanadacha; Woraphan Chaisriratanakul; Ekalak Chaowicharat; Wutthinan Jeamsaksiri

doi:10.1016/j.talanta.2019.120305

Optimization of 3-aminopropyltriethoxysilane functionalization on silicon nitride surface for biomolecule immobilization

Talanta. 2020 Jan 15:207:120305. doi: 10.1016/j.talanta.2019.120305. Epub 2019 Sep 6.

Authors

Pawasuth Saengdee¹, Chamras Promptmas², Surachoke Thanapitak³, Awirut Srisuwan⁴, Apirak Pankiew⁴, Nutthaphat Thornyanadacha⁴, Woraphan Chaisriratanakul⁴, Ekalak Chaowicharat⁴, Wutthinan Jeamsaksiri⁴

Affiliations

¹ Thai Microelectronic Center (TMEC), National Electronics and Computer Technology Center (NECTEC), 112 Phahonyothin Road, Khlong Nueng, Khlong Luang District, Pathumthani 12120, Thailand. Electronic address: pawasuth.saengdee@nectec.or.th.
² Department of Biomedical Engineering, Faculty of Engineering, Mahidol University, Nakhon Pathom 73170, Thailand.
³ Department of Electrical Engineering, Faculty of Engineering, Mahidol University, Nakhon Pathom 73170, Thailand.
⁴ Thai Microelectronic Center (TMEC), National Electronics and Computer Technology Center (NECTEC), 112 Phahonyothin Road, Khlong Nueng, Khlong Luang District, Pathumthani 12120, Thailand.

PMID: 31594628
DOI: 10.1016/j.talanta.2019.120305

Abstract

The 3-aminopropyltriethoxysilane (APTES) is a common method for biomolecule immobilization on silicon and silicon derivatives such as silicon nitride (Si₃N₄). However, there are many parameters which impact the efficiency of APTES modification such as APTES concentration and reaction time. Thus, various APTES concentrations (0.1%, 0.5%, 1%, 2%, 5%, and 10%) under different reaction times (15, 30, 60 and 120 min) were compared to achieve the optimal APTES modification condition which produced a thin and stable APTES layer on Si₃N₄ surface. The modified surfaces were characterized by contact angle (CA) measurement, Fourier transform infrared (FTIR) spectroscopy and spectroscopic ellipsometry to determine the wetting property, chemical bonding composition and surface thickness, respectively. In addition, biotin was used as a model to determine the effectiveness of APTES modification condition by coupling with glutaraldehyde (GA). The Alexa Flour 488 conjugated streptavidin was performed to visualize the presence of biotin using fluorescence microscopy due to the specifically binding between biotin and streptavidin. The atomic force microscopy (AFM) was utilized to determine the surface topology which was an indicator to demonstrate the agglomeration of APTES molecule. Moreover, ion sensitive field effect transistor (ISFET) was employed as a biosensor model to demonstrate the effect between surface thickness and sensitivity of biosensor. The results show that the APTES thickness is directly correlated to the APTES concentration and reaction time. Since the importance parameter for ISFET measurement is the distance between biomolecule and sensing membrane of ISFET, the thicker APTES layer negatively impacts the sensitivity of ISFET based biosensor because of the ion shielding effect. Therefore, these results would be valuable information for development of Si₃N₄ biosensor, especially ISFET based biosensor.

Keywords: Aminopropyltriethoxysilane; ISFET; Silanization; Silicon nitride; Surface modification.

MeSH terms

Biosensing Techniques / methods*
Glutaral / chemistry
Kinetics
Propylamines / chemistry*
Silanes / chemistry*
Silicon Compounds / chemistry*
Surface Properties
Transistors, Electronic

Substances

Propylamines
Silanes
Silicon Compounds
amino-propyl-triethoxysilane
silicon nitride
Glutaral