Characterization of Ultraflat Titanium Oxide Surfaces

The nanoscale surface topography of biomaterials can have strong effects on protein adsorption. While there are numerous surface statistical parameters for the characterization of nanorough surfaces, none of them alone provides a complete description of surface morphology. Herein, a selection of nanorough titanium oxide surfaces has been fabricated with root-mean-square roughness (Sq) values below 2.7 nm but very different surface morphologies. The adsorption of the proteins myoglobin (MGB), bovine serum albumin (BSA), and thyroglobulin (TGL) at these surfaces was investigated in situ by ellipsometry to assess the importance of six of the most common surface statistical parameters. For BSA adsorption, both protein film thickness and time constant of adsorption were found to scale linearly with Sq s. For TGL, however, the same adsorption characteristics depend linearly on the surface skewness (Ssk), which we attribute to the rather extreme size of this protein. Finally, a mixed behavior is observed for MGB adsorption, showing different linear correlations with Sq and Ssk. These results demonstrate the importance of a thorough morphological characterization of the surfaces employed in protein adsorption and possibly also cell adhesion studies.

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Simultaneous Kinetics of Selenite Oxidation and Sorption on δ-MnO2 in Stirred-Flow Reactors

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18062902 ◽

2021 ◽

Vol 18 (6) ◽

pp. 2902

Author(s):

Zheyong Li ◽

Yajun Yuan ◽

Lin Ma ◽

Yihui Zhang ◽

Hongwei Jiang ◽

...

Keyword(s):

Rate Constant ◽

Photoelectron Spectroscopy ◽

Oxide Surfaces ◽

Kinetic Rate Constant ◽

Flow Reactors ◽

Mn Oxide ◽

Remediation Strategies ◽

Process Of Se ◽

Kinetics Of

Selenium (Se) is an essential and crucial micronutrient for humans and animals, but excessive Se brings negativity and toxicity. The adsorption and oxidation of Se(IV) on Mn-oxide surfaces are important processes for understanding the geochemical fate of Se and developing engineered remediation strategies. In this study, the characterization of simultaneous adsorption, oxidation, and desorption of Se(IV) on δ-MnO2 mineral was carried out using stirred-flow reactors. About 9.5% to 25.3% of Se(IV) was oxidized to Se(VI) in the stirred-flow system in a continuous and slow process, with the kinetic rate constant k of 0.032 h−1, which was significantly higher than the apparent rate constant of 0.0014 h−1 obtained by the quasi-level kinetic fit of the batch method. The oxidation reaction was driven by proton concentration, and its rate also depended on the Se(IV) influent concentration, flow rate, and δ-MnO2 dosage. During the reaction of Se(IV) and δ-MnO2, Mn(II) was produced and adsorbed strongly on Mn oxide surfaces, which was evidenced by the total reflectance Fourier transform infrared (ATR-FTIR) results. The X-ray photoelectron spectroscopy (XPS) data indicated that the reaction of Se(VI) on δ-MnO2 produced Mn(III) as the main product. These results contribute to a deeper understanding of the interface chemical process of Se(IV) with δ-MnO2 in the environment.

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