阵列纳米通道中氨基官能团质子化研究

Protonization of Amino Functional Groups Confined in Nanochannels

质子化过程是大多数酸碱理论的核心,也发生在许多生命过程中.因此,研究限域环境中分子或官能团的质子化过程将为进一步认识酸碱理论和阐述限域环境中生物分子的基本行为提供理论依据.本文提出了一种以荷电电化学探针检测多孔氧化铝阵列纳米通道内表面官能团质子化过程的新方法.该方法利用纳米通道表面官能团的质子化过程改变表面荷电性质,从而调控荷电电化学探针在纳米通道中的传输行为.实验中以喷涂在阵列氧化铝纳米通道膜一侧的薄金膜为工作电极,检测通过阵列纳米通道荷电电化学探针的流量,以此获得纳米通道限域条件下的质子化过程.同时以多孔氧化铝阵列纳米通道为限域空腔,利用硅烷化反应将氨基修饰在纳米通道的内表面,通过不同pH值条件下检测Fe(CN)63-离子在纳米通道中流量的变化,获得了纳米通道限域条件下氨基质子化滴定曲线.结果表明,纳米通道限域条件下氨基官能团发生一步质子化,其pK1/2值为5.9.本文提出的方法也适用于研究纳米通道限域条件下其它官能团或生物分子的质子化过程.

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 un- derstanding 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 titra- tion curve for the protoniation of amine groups in nanochannel confined condition is obtained by measuring the current signal of ferricyanide probe flowing through an anino-anchored PAA nanochannel array at different solu- tion pH. Results show that the protonization of amino group in nanochannel occurs in one step with a pKl/2 = 5.9. The present method provides an effective tool to study the protonization processes of various functional groups and biomoelcuels.