Adsorption and Mechanism of Glycine on the Anatase with Exposed (001) and (101) Facets

Zeling Liu; Xiaomei Zhong; Yifan Liu; Hanyun Rao; Hongfu Wei; Wenyuan Hu; Xiaoqin Nie; Mingxue Liu

doi:10.3390/min12070798

Minerals (Jun 2022)

Adsorption and Mechanism of Glycine on the Anatase with Exposed (001) and (101) Facets

Zeling Liu,
Xiaomei Zhong,
Yifan Liu,
Hanyun Rao,
Hongfu Wei,
Wenyuan Hu,
Xiaoqin Nie,
Mingxue Liu

Affiliations

Zeling Liu: School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
Xiaomei Zhong: School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
Yifan Liu: School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
Hanyun Rao: School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
Hongfu Wei: School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
Wenyuan Hu: School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
Xiaoqin Nie: School of National Defense Science and Technology, Southwest University of Science and Technology, Mianyang 621010, China
Mingxue Liu: School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China

DOI: https://doi.org/10.3390/min12070798
Journal volume & issue: Vol. 12, no. 7
p. 798

Abstract

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As a widely existing mineral types on Earth, semiconductor minerals play an important role in the origin of life and the material geochemical cycle. The first step of peptide formation is amino acid adsorption on the mineral surface, but the role and mechanism of different crystal facets of semiconductor minerals are not well understood. Anatase (TiO2) with exposed (001) facets was synthesized by a hydrothermal method, and then analyzed and compared with the purchased ordinary anatase (TiO2) for the adsorption of glycine, the simplest amino acid. XRD, SEM and TEM results show that the hydrothermally synthesized anatase (TiO2) has a good anatase crystal form, which is micro-nano-scale flake particles and mainly composed of (001) facets. The results of HPLC used in the adsorption experiment showed that under optimal conditions (pH 5 to 6, an adsorption time of 24 h, and an initial concentration of 0.09 mol/L), the adsorption quantity of glycine on anatase (TiO2) with exposed (001) facets may reach 10 mg/m2, which is larger than that for ordinary anatase (TiO2) with exposed (101) facets. Based on a combination of various characterizations and simulation calculations, the results proved that anatase can activate thermodynamically stable γ-glycine to β-glycine. The adsorption of glycine on anatase (TiO2) has two forms, one is the zwitterionic form in which the carboxyl group forms a bridge structure with two Ti atoms connected by surface bridging oxygen, and the dissociated form is in which the amino group forms a bond with the surface Ti atom. Among these, glycine is mainly adsorbed to anatase by dissociative molecules on the anatase (TiO2) with exposed (001) facets and by zwitterion adsorption on the anatase (TiO2) with exposed (101) facets. This research elucidates the conditions and mechanism of amino acid adsorption by semiconductor minerals in weak acidic environment, which is similar to the environmental pH that was beneficial to the formation of life on the early Earth. Therefore, these can provide a reference for the further study of the role of semiconductor minerals in the adsorption and polymerization of small biomolecules in the origin of life.

Published in Minerals

ISSN: 2075-163X (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Science: Geology: Mineralogy
Website: https://www.mdpi.com/journal/minerals

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