关键词: 多孔氧化铝模板, 质子化, 等电点, 限域效应, 电化学分析

Abstract: Protonization process is the key step of acid-base reaction and occurs in many biological processes. Study of the protonization process of molecules and/or functional groups in confined conditions would assist understanding in the acid-base theory and confinement effect of biomolecules. In this paper, we developed a novel approach to study protonization of functional groups in porous anodic alumina array nanochannels by measuring the flux of electrochemical active probes using an Au film electrochemical detector sputtered at the end of the nanochannels. The protonization status of the surface functional groups in nanochannels can change the surface charges and further modulate the transportation of charged electroactive probes through nanochannels. The titration curve for the protoniation of amine groups in nanochannel confined condition is obtained by measuring the current signal of ferricyanide probe flowing through an anime-anchored PAA nanochannel array at different solution pH. Results show that the protonization of amino group in nanochannel occurs in one step with a pK1/2=5.9. The present method provides an effective tool to study the protonization processes of various functional groups and biomoelcuels.

Key words: porous anodic alumina, protonization, isoelectric point, confinement effect, electrochemical analysis