Interaction of aluminium hydrolytic species with biomolecules

In this contribution the formation of bioinorganic assemblies between the basic globular protein lysozyme and aqueous aluminium species including Al 13 -mer, Al 30 -mer and colloidal aluminium hydroxide have been explored and comparison made to previous interaction studies performed with bovine serum albumin (BSA). Specific charge-stabilised bioinorganic assemblies involving aluminium species and lysozyme were observed to form in contrast to the gel like structures formed on interaction of BSA with aluminium species. As demonstrated by infrared spectroscopy (structural assignment, 2D correlation spectroscopy), interactions mostly involve acidic surface groups of the proteins (Asp, Glu), with strong complexation and deprotonation in the case of BSA interacting with Al 13 and Al 30 and through hydrogen bonding for lysozyme interacting with the same species and aluminium hydroxide particles interacting with both biomolecules

Fabrication, characterisation and performance of hydrophilic and super-hydrophilic silica as cell culture surfaces

We demonstrate a straightforward procedure for the controlled formation of silica films on tissue culture polystyrene (PS) surfaces. The films were formed by sequentially treating PS with polyaniline, glutaric dialdehyde and protein prior to silica formation. The films could be tailored to exhibit superhydrophilicity (contact angle < 5°) which was retained for more than two months under ambient conditions. Both hydrophilic and super-hydrophilic silica coated surfaces were suitable for the culture of an adherent human melanoma cell line. Proliferation, toxicity and adhesion assays were used to compare cell behaviour. Cells on the silica surfaces showed enhanced adhesion and comparable rates of cell proliferation as compared to cells grown on conventional tissue culture plastic. The results obtained can be understood by considering the surface properties of the different materials and the ability of the silica coated surfaces to adsorb significantly higher levels of serum proteins from the growth medium. One of the outcomes of this study is a re-evaluation of the hydrophobicity/hydrophilicity characteristics required for good cell growth and the possibility of designing new tissue culture materials capable of greater control over cell populations

Peptide-directed crystal growth modification in the formation of ZnO

Biomolecule-mediated synthesis is fascinating in terms of the level of control and the intricate hierarchical structures of the materials that can be produced. In this study we compare the behavior of a phage display identified peptide, EAHVMHKVAPRP (EM-12) with that of a mutant peptide EAHVCHKVAPRP (EC-12), having additional complexation capability, on the formation of ZnO from solution. The synthesis conditions (Zn(CH3COO)2–NH3 hydrothermal method at 50 °C) were chosen to generate rod-shaped ZnO via layered basic zinc salts (LBZs) as intermediates. Both peptides affected the crystal formation process by moderating the amount of Zn2+ ions in solution (EC12 having a greater effect than EM12) but only EC12 was shown to interact with the solid phase(s) formed during the reaction. Depending on the peptide concentration used, EM-12 was shown to delay and/or suppress ZnO formation. In contrast, additions of EC-12, although leading to the retention of higher levels of Zn2+ ions in solution did not similarly delay the transformation of the intermediate phases to ZnO but were found to dramatically modify the morphology of ZnO crystallites with mushroom shaped crystals being formed. From the results of detailed materials characterization and changes in the morphology observed, the interactions between the peptide(s) and solution and solid state species present during the process of ZnO crystal formation in the presence of EM-12 and EC-12 are proposed

A Review on Recent Patents and Applications of Inorganic Material Binding Peptides

Over the past decade, significant progress has been made in the identification of novel material binding peptides having affinity to a wide range of target materials and their use in nanobiotechnological innovations. These material binding peptides (MBPs), also known as solid/ substance binding peptides (SBPs) can be isolated using combinatorial display technologies such as phage display (PD), surface display (cell, bacterial, yeast, mRNA) exhibit material specific selectivity and affinity towards a range of inorganic and organic nanomaterial surfaces including metals, metal oxides, minerals, semiconductors and biomolecules. MBPs serve as mediators in bringing nanotechnology and biotechnology under one umbrella by linking solid nanoparticles with biomolecules including proteins, bioactive peptide motifs, bifunctional binding peptides, enzymes, antigens and antibody fragments. As the utilization and application of these inorganic binding peptides as molecular connectors, molecular assemblers and material specific synthesizers in nanotechnology has been expanding rapidly, so too has growing commercial interest in patenting such innovations. In this review, we present the past, current and future developments and applications of inorganic MBPs specific to nanomaterials and their applications

Combined release of platelet-rich plasma and 3D-mesenchymal stem cell encapsulation in alginate hydrogels modified by the presence of silica

We report the modified release of platelet-rich plasma from alginate platelet-rich plasma hydrogels altered by the presence of silica. These PRP–alginate–silica compositions can be used as injectable carriers for viable mesenchymal stem cells

Triethylphosphite as a network forming agent enhances in-vitro biocompatibility and corrosion protection of hybrid organic-inorganic sol-gel coatings for Ti6Al4V alloys

The biocompatibility and life of metallic implants can be enhanced through improving the biocompatibility and corrosion protection characteristics of the coatings used with these materials. In this study, triethylphosphite (TEP) was used to introduce phosphorus into organic-inorganic hybrid silica based sol gel coatings prepared using γ-methacryloxypropyltrimethoxysilane and tetramethylorthosilicate. Addition of TEP dramatically increased the rate of intermolecular condensation and resulted in materials showing greater cross linking. Protein (fibrinogen) uptake, osteoblast in vitro biocompatibility and corrosion resistance was enhanced in coatings containing TEP. Although higher concentrations of phosphorus supported the greatest improvement in biocompatibility, a compromise in the phosphorus concentration used would be required if corrosion resistance was most desirable parameter for optimisation. Films prepared by dip coating on Ti6Al4V alloys from these sols offer a promising alternative to wholly metallic prostheses

Traditional materials from new sources – conflicts in analytical methods for calcium carbonate

Calcium carbonate, (E170) is a common food and pharmaceutical additive/ingredient. In addition to a source of calcium, the carbonate has uses including as a colour, acidity regulator and bulking agent. Globally, a range of regulatory agencies and pharmacopoeia control the analyses and specification of additives in food, supplements, pharmaceutical substances and excipients. Accordingly, a range of specifications and analyses exist for calcium carbonate depending on the application and market of the product. In this contribution, we analyse calcium carbonates from geological, synthetic and biogenic sources, focussing on acid insoluble impurities, a test required by current monographs. Analysis of calcium carbonate from different origins may require modification of existing tests to comply with regulatory bodies, due to the variation of impurities specific to the source of the material. We suggest an analytical approach involving centrifugation that improves analytical efficiency (up to 85% time reduction), especially for calcium carbonate of biological origin

A robust spectroscopic method for the determination of protein conformational composition - application to the annealing of silk

The physical and mechanical properties of structural proteins such as silk fibroin can be modified by controlled conformational change, which is regularly monitored by Fourier transform infrared spectroscopy by peak fitting of the amide I band envelope. Although many variables affecting peak shape are well established, there is no fixed methodology to compare and follow secondary structural differences without significant operator input especially where low frequency spectral noise is a problem. The aim of this contribution is to establish a method for such analyses to be carried at high levels of autonomy to prevent subjective or erroneous fitting. A range of approaches was trialled with optimal peak parameters selected based on overall goodness of fit and reproducibility of fit of replicate sample spectra. The method was successfully tested against reference proteins having contrasting β content and the rationale for parameter selection is presented. Further, we applied this method to measure the effect of conformational change on the energy of the amide I band of silk fibroin during annealing. Energy changes were ca. 400 kJ mol−1 of fibroin. To confirm that this energy change was a consequence of increased hydrogen bonding we used a Thioflavin T staining method typically used to identify β aggregate type structures in amyloid plaques. We propose that the approach described herein can aid in the development of silk based materials for biomedical applications where tuning of the physical and mechanical properties of the silk are needed to guarantee optimum activity

From phage display to structure: interplay of enthalpy and entropy in binding of LDHSLHS polypeptide to silica

Polypeptide based biosilica composites show promise as next generation multi-functional nano-platforms for diagnostics and bio-catalytic applications. Following identification of a strong silica binder (LDHSLHS) by phage display, we conduct structural analysis of the polypeptide at the interface with amorphous silica nanoparticles in an aqueous environment. Our approach relies on modelling of Infrared and Raman spectral responses using predictions of molecular dynamics simulations and quantum studies of the normal modes for several potential structures. By simultaneously fitting both Infrared and Raman responses in the Amide spectral region, we show that the main structural conformer has a beta-like central region and helix-twisted terminals. Classical simulations, as conducted previously (Chem. Mater., 2014, 26, 5725), predict that association of the main structure with the interface is stimulated by electrostatic interactions though surface binding also requires spatially distributed sodium ions to compensate negatively charged acidic silanol groups. Accordingly, diffusion of sodium ions would contribute to a stochastic character of the peptides association with the surface. Consistent with the described dynamics at the interface, results from isothermal titration calorimetry (ITC) confirm significant enhancement of polypeptide binding to silica under higher concentrations of Na+. The results of this study suggest that the tertiary structure of a phage capsid protein plays a significant role in regulating the conformation of peptide LDHSLHS, increasing its binding to silica during the phage display process. The results presented here support design-led engineering of polypeptide-silica nanocomposites for bio-technological applications

Correction: Azamacrocycles and tertiary amines can be used to form size tuneable hollow structures or monodisperse oxide nanoparticles depending on the 'M' source

Correction for 'Azamacrocycles and tertiary amines can be used to form size tuneable hollow structures or monodisperse oxide nanoparticles depending on the ‘M’ source' by Graham E. Tilburey, et al., Dalton Trans., 2019, 48, 15470–15479. The authors would like to correct the author list, as S. V. Patwardhan is not included on the author list in the published article. The correct author list is shown above. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers