Future Industries Institute, University of South Australia, Mawson Lakes, South Australia 5095, Australia.
Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9016, New Zealand.
Langmuir. 2021 Nov 16;37(45):13278-13290. doi: 10.1021/acs.langmuir.1c01830. Epub 2021 Nov 3.
The technique of in situ particle film attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR) has been used to probe the adsorption and coadsorption (sequential) of a common food protein (β-lactoglobulin, BLG) and two representative bile salts (taurocholic acid and glycocholic acid, abbreviated as TCA and GCA) onto the surface of titanium dioxide (TiO) nanoparticles. Evaluating of binding interactions between commonly used (historically now, in some countries) food additives and food components, as well as the body's own digestion chemicals, is a critical step in understanding the role of colloidal phenomena in digestion and bioavailability. TCA is found to adsorb onto TiO but without any significant ability to be retained when it is not present in the aqueous phase. GCA is also found to adsorb via two distinct binding mechanisms, with one type of adsorbed species being resistant to removal. BLG adsorbs, is irreversibly bound, and has altered conformation when adsorbed at pH 2 (stomach conditions) to the conformation when adsorbed at pH 6.5 (small intestine conditions). This altered conformation is not interface-dependent and is mirrored in the solution spectra of BLG. Sequential coadsorption studies indicate that TCA and GCA adsorb onto TiO nanoparticle surfaces and display similar degrees of reversibility and binding in the presence or absence of preadsorbed BLG.
原位粒子膜衰减全反射傅里叶变换红外光谱（ATR FTIR）技术已被用于探测常见食品蛋白（β-乳球蛋白，BLG）和两种代表性胆汁盐（牛胆酸和甘胆酸，简称 TCA 和 GCA）在 TiO2 纳米粒子表面的吸附和共吸附（顺序）。评估常用（历史上，在某些国家）食品添加剂和食品成分与体内消化化学物质之间的结合相互作用，是理解胶体现象在消化和生物利用度中作用的关键步骤。TCA 被发现吸附在 TiO 上，但在不存在水相时没有任何被保留的能力。GCA 也被发现通过两种不同的结合机制吸附，其中一种吸附物种具有抗去除能力。BLG 在 pH 2（胃条件）吸附时会吸附、不可逆结合并改变构象，而在 pH 6.5（小肠条件）吸附时则保持构象。这种改变的构象不依赖于界面，并且在 BLG 的溶液光谱中得到了反映。顺序共吸附研究表明，TCA 和 GCA 吸附在 TiO2 纳米粒子表面上，并在存在或不存在预吸附 BLG 的情况下显示出相似程度的可逆性和结合。
