Wadu-Mesthrige K, Amro N A, Liu G Y
Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA.
Scanning. 2000 Nov-Dec;22(6):380-8. doi: 10.1002/sca.4950220607.
The immobilization of protein molecules on self-assembled monolayers (SAM) by physical interactions and chemical bonding has been studied using atomic force microscopy (AFM). The proteins used for our investigation are bovine serum albumin (BSA), lysozyme (LYZ), and normal rabbit immunoglobulin G (IgG). The surfaces are methyl-, hydroxyl-, carboxylic acid- and aldehyde-terminated SAMs. We found that BSA and LYZ can be readily immobilized on SAMs at their isoelectric point (IEP). The detailed surface morphology of adsorbed proteins varies with the functionality of the SAMs. The strong hydrophobic interaction at the IEP is attributed to immobilization. If the solution pH is deviated from the IEP, proteins may be attached onto the surface via electrostatic interactions. Covalent binding between the aldehyde-terminated SAM and the H2N-groups in the protein results in immobilization of all three proteins. The individual proteins and their orientations on SAMs are clearly resolved from high-resolution AFM images. The stability and bioactivity of these immobilized proteins are also studied.
利用原子力显微镜（AFM）研究了通过物理相互作用和化学键合将蛋白质分子固定在自组装单分子层（SAM）上的情况。用于我们研究的蛋白质是牛血清白蛋白（BSA）、溶菌酶（LYZ）和正常兔免疫球蛋白G（IgG）。这些表面是甲基、羟基、羧酸和醛端基的SAM。我们发现，BSA和LYZ在其等电点（IEP）时可以很容易地固定在SAM上。吸附蛋白质的详细表面形态随SAM的功能而变化。IEP处的强疏水相互作用归因于固定化。如果溶液pH偏离IEP，蛋白质可能通过静电相互作用附着在表面。醛端基SAM与蛋白质中的H2N基团之间的共价结合导致所有三种蛋白质的固定化。从高分辨率AFM图像中可以清楚地分辨出SAM上的单个蛋白质及其取向。还研究了这些固定化蛋白质的稳定性和生物活性。
