Investigating adsorption and self-assembly of alkanethiol monolayers on gold surface using molecular dynamic simulations

• Main Authors: Yu-Chia Liao, 廖郁嘉
• Other Authors: Chuin-Shan Chen
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/36458920934706765474

碩士 === 國立臺灣大學 === 土木工程學研究所 === 104 === Microcantilever-based biosensors have received much attention because of the features of convenience, high precision, and low cost. Alkanethiol is a common self-assembled monolayer used to link the surface of microcantilever-based biosensors and biorecognition elements. The adsorption and chain length effects of alkanethiols on gold affect the sensing results and sensitivity of microcantilever-based biosensors. The objective of this work is to understand the kinetics and mechanisms of alkanethiols adsorption with varying chain length. The understanding will shed light on the design of microcantilever-based biosensors in the future.. Molecular dynamics simulations are used to analyze the adsorption of alkanethiol self-assembled monolayers on Au(111). The influence of adsorption coverage on tilting angle of alkanethiols and formation of self-assembled monolayers is observed. Two different concentrations (0.540M、1.080M) and four different chain lengths (2、6、10、14) of alkanethiols are also discussed. The simulation results show that alkanethiols are mobile on gold surface with low coverage and immobile with higher coverage. In the process of adsorption, the distribution of alkanethiols tilting angle changes when certain coverage is reached, and this coverage decreased with longer chain length of alkanethiols. While the coverage exceeds the limit of lying phase, alkanethiols with small tilting angle begin to be scattered on gold surface. Moreover, the structure is more disordered and no distinct formation phases are observed for alkanethiols with short chain length.