(216ad) Quartz Crystal Microbalancing Based On Vapor-Deposited Reactive Coatings

Quartz Crystal Microbalancing Based on Vapor-Deposited Reactive Coatings

Yung-Chih Chen^a, Ting-Ju Lin^a, Wei-Bor Tsai^a, Hsien-Yeh Chen^a

Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan

E-mail: hsychen@ntu.edu.tw

Abstract

Quartz crystal microbalancing (QCM) is a simple, cost-effective, and high-resolution mass sensing technique that the analysis is based upon the piezoelectric effect for measure mass densities down to a level of below 1 μg/cm². QCM evolved a solution measurement capability in largely analytical chemistry and electrochemistry applications due to its sensitive solution-surface interface measurement capability, and has widely be used for investigating the behavior of biomolecule adsorption or desorption in many biological applications. In order to perform sophisticated biological sensing , controlled surface chemistry of introducing sensing molecules on surfaces of quartz crystals usually requires substantial knowledge to conduct surface modification on such crystals, and an optimal modification approach has to be identified in a case-by-case fashion with selected methods. Functionalized poly(p-xylylene) coatings are used to provide versatile anchoring sites for the immobilization of sensing molecules on quartz crystals, as they decouple surface design from bulk properties and require minimum knowledge on surface chemistry of the underlying materials.

A multicomponent poly(p-xylylene) coating that contains two distinctly-addressable reactive moieties of electron-deficient alkynes and unsaturated maleimides is chosen as the model system to modify on crystal surface in the current study. The platform has provided i) maleimide groups for immobilization of thiol-PEG via thiol-maleimide coupling to render a surface that eliminates undesired perturbance from fouling substances, and ii) alkyne sites for immobilization of azide-biotin via azide-alkyne click reaction to activate biological functions. The modified quartz crystal is allowed for the quantitative measurement of subsequently attached streptavidin and biotinylated antibody. The herein reported coating technology may be broadly applicable to a wide range of different functional groups of poly-p-xylylenes and are extendable to attach other sensing molecules of detection. We envision the technique can provide a solution to the development of a robust QCM sensing tool for diagnostic applications.