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Considering the vast importance of peptide and protein interactions with inorganic surfaces, probing hydrogen bonding during their adsorption on metal oxide surfaces is a relevant task that could shed light on the essential features of their interplay. This work is devoted to studying the dipeptides' adsorption on anatase nanoparticles (ANs) in light and heavy water to reveal differences arising upon the change of the major hydrogen bonding carrier. Thermodynamic study of six native dipeptides' adsorption on ANs in both media shows a strong influence of the solvent on the Gibbs free energy and the effect of side-chain mobile protons on the entropy of the process. The adsorption is endothermic irrespective of the medium and is entropy-driven. Computer simulations of peptide adsorption in both media shows similarity in binding via an amino group and demonstrates structural features of protonated and deuterated peptides in obtained complexes. Calculated peptide- anatase nanoparticle (AN) descriptors indicate surface oxygens as points of peptide-nanoparticle contacts.

Fundamentals of inorganic-organic interactions are critically important in the discovery and development of novel biointerfaces amenable for utilization in biotechnology and medicine. Recent studies indicate that proteins interact with surfaces through limited adsorption sites. Protein fragments such as amino acids and peptides can be used for interaction modeling between complex biological macromolecules and inorganic surfaces. During the last three decades, many valid and sensitive methods have been developed to measure the physical chemistry fundamentals of those interactions: isothermal titration calorimetry (ITC), surface plasmon resonance (SPR), quartz crystal microbalance (QCM), total internal reflection fluorescence (TIRF), and attenuated total reflectance spectroscopy (ATR). The simplest and most affordable technique for the measurement of adsorption is the depletion method, where the change in sorbate concentration (depletion) after contact with solution-dispersed sorbent is calculated and assumed to be adsorbed. Adsorption isotherms based on depletion data provide all basic physicochemical data. However, adsorption from solutions requires longer equilibration times due to kinetic restrictions and sorbents with a high specific surface area, making it almost inapplicable to macroscopic fixed plane surfaces. Moreover, factors such as the instability of sols, nanoparticle aggregates, sorbent crystallinity, nanoparticle size distribution, pH of the solution, and competition for adsorption, should be considered while studying adsorbing peptides. Depletion data isotherm construction provides comprehensive physical chemistry data for literally every soluble sorbate yet remains the most accessible methodology, as it does not require expensive setups. This article describes a basic protocol for the experimental study of peptide adsorption on inorganic oxide and covers all critical points that affect the process.

The affinity of biomolecules, such as peptides and proteins, with inorganic surfaces, is a fundamental topic in biotechnology and bionanotechnology. Amino acids are often used as “model” bits of peptides or proteins for studying their properties in different environments and/or developing functional surfaces. Despite great demand for knowledge about amino acid interactions with metal oxide surfaces, studies on the issue represent a fragmentary picture. In this paper, we describe amino acid adsorption on nanocrystalline anatase systematically at uniform conditions. Analysis of the Gibbs free adsorption energy indicated how the aliphatic, aromatic, polar, and charged side chain groups affect the binding affinity of the amino acids. Thermodynamic features of the L-amino acid adsorption receive thorough interpretation with calculated molecular descriptors. Theoretical modelling shows that amino acids complex with TiO2 nanoparticles as zwitterions via ammonium group., This work was financially supported by the Russian Foundation for Basic Research (grant no. 15-03-07834-a). I.K. acknowledge the financial support from Spanish MINECO (CTQ2014-52956-C3-1-R and MAT2016-78155-C2-1-R).

The present study is focused on the fabrication of magnetic poly(3-hydroxybutyrate)-based core–shell fibers decorated with titanium dioxide (TiO2) as an original and simple approach for the development of novel and effective recyclable hybrid materials designed for purification of waters from organic pollutants. For the first time that was achieved successfully in one-step by simultaneous coaxial electrospinning and electrospraying. Coaxial electrospinning resulted in fabrication of fibers with a core of Fe3O4 nanoparticles in poly(vinyl alcohol) and a shell of poly(3-hydroxybutyrate) and poly(e-caprolactone). Simultaneously, the surface of electrospun core–shell fibers was purposely decorated with TiO2 nanoparticles by electrospraying of an aqueous dispersion of nano-sized TiO2. The core–shell structure was evidenced by transmission electron and fluorescence microscopies. It was found that this structure and the presence of the inorganic components had an impact on the thermal properties and the crystallinity of the novel hybrid fibrous materials. Moreover, the prepared materials displayed magnetic properties and enhanced tensile strength. Furthermore, the targeted decoration of TiO2 nanoparticles provided excellent photocatalytic activity of the materials under UV light irradiation even after threefold use.

Surface properties of the nanostructured materials are essential in attaining particular functionality, which is why there are a plethora of surface modification methods applied during or past the synthesis of nanoparticular substrates. Depending on the resulting content of the surface it could be heterophase forming modifications or pristine titania modifications. In this communication, we study a novel approach to pristine titania surface alteration by controlled chemisorption of the stable water-soluble titanium complex on the nanocrystalline anatase. Following on-air calcination for removal of organic residues converts chemisorbed complexes into oxide phase increments. Such an approach retains crystallinity and specific surface with simultaneous withdrawal of surface hydroxyl groups.

The affinity of biomolecules, such as peptides and proteins, with inorganic surfaces, is a fundamental topic in biotechnology and bionanotechnology. Amino acids are often used as "model" bits of peptides or proteins for studying their properties in different environments and/or developing functional surfaces. Despite great demand for knowledge about amino acid interactions with metal oxide surfaces, studies on the issue represent a fragmentary picture. In this paper, we describe amino acid adsorption on nanocrystalline anatase systematically at uniform conditions. Analysis of the Gibbs free adsorption energy indicated how the aliphatic, aromatic, polar, and charged side chain groups affect the binding affinity of the amino acids. Thermodynamic features of the l-amino acid adsorption receive thorough interpretation with calculated molecular descriptors. Theoretical modeling shows that amino acids complex with TiO

Several types of nanostructured hybrid fibrous materials containing poly(3-hydroxybutyrate), nanoparticles from iron oxide (Fe3O4) and titanium dioxide (TiO2), and chitosan or chitosan oligosaccharides (COS) were prepared. The design of the surface of the materials and their magnetic properties were tailored purposefully by conjunction of electrospinning and electrospraying. The surface and bulk morphologies of the obtained nanostructured materials were examined by SEM. Further, the distribution of Fe3O4 and TiO2 nanoparticles was estimated by TEM analyses, as well as their surface chemical composition was determined by XPS. It was found that the simultaneous electrospinning and electrospraying of Fe3O4/chitosan or TiO2/COS dispersions resulted in uniform distribution of the nanoparticles along the length of the fibers, while electrospraying of the mixed Fe3O4/TiO2/chitosan dispersion led to agglomerate formation. Furthermore, the nanostructured hybrid materials preserved the magnetic properties of Fe3O4 embedded therein. It was demonstrated that the hybrid materials of different designs displayed excellent photocatalytic activity under UV light irradiation against a model organic contaminant—methylene blue, even after threefold use of the materials.

Several types of fibrous material containing poly(3-hydroxybutyrate) (PHB), nanosized TiO2 -anatase (nanoTiO2 ), and chitosan oligomers are prepared by combining the electrospinning, electrospraying, and impregnation techniques. Simultaneous electrospinning/electrospraying provides uniform distribution of electrosprayed nanoTiO2 along the PHB fibers and throughout the mat. Hybrid materials of different design manifest excellent photocatalytic activity, even after repeated use. They exhibit high bactericidal activity against Escherichia coli. In addition, the fibrous scaffolds are compatible with human mesenchymal stem cells and provide a favorable environment for their development.