Characterization of protein and peptide binding to nanogels formed by differently charged chitosan derivatives.

Chitosan (Chi) is a natural biodegradable cationic polymer with remarkable potency as a vehicle for drug or vaccine delivery. Chi possesses multiple groups, which can be used both for Chi derivatization and for particle formation. The aim of this work was to produce stable nanosized range Chi gels (nanogels, NGs) with different charge and to study the driving forces of complex formation between Chi NGs and proteins or peptides. Positively charged NGs of 150 nm in diameter were prepared from hexanoyl chitosan (HC) by the ionotropic gelation method while negatively charged NGs of 190 nm were obtained from succinoyl Chi (SC) by a Ca²âº coacervation approach. NGs were loaded with a panel of proteins or peptides with different weights and charges. We show that NGs preferentially formed complexes with oppositely charged molecules, especially peptides, as was demonstrated by gel-electrophoresis, confocal microscopy and HPLC. Complex formation was accompanied by a change in zeta-potential and decrease in size. We concluded that complex formation between Chi NGs and peptide/proteins is mediated mostly by electrostatic interactions.

Preparation and biocompatibility evaluation of pectin and chitosan cryogels for biomedical application.

Today, there is a need for the development of biomaterials with novel properties for biomedical purposes. The biocompatibility of materials is a key factor in determining its possible use in biomedicine. In this study, composite cryogels were obtained based on pectin and chitosan using ionic cryotropic gelation. For cryogel preparation, apple pectin (AP), Heracleum L. pectin (HP), and chitosan samples with different physical and chemical characteristics were used. The properties of pectin-chitosan cryogels were found to depend on the structural features and physicochemical characteristics of the pectin and chitosan within them. The addition of chitosan to cryogels can increase their mechanical strength, cause change in surface morphology, increase the degradation time, and enhance adhesion to biological tissues. Cryogels based on AP were less immunogenic when compared with cryogels from HP. Cryogels based on AP and HP were hemocompatible and the percentage of red blood cells hemolysis was less than 5%. Unlike cryogels based on HP, which exhibited moderate cytotoxicity, cryogels based on AP exhibited light cytotoxicity. Based on the results of low immunogenicity, light cytotoxicity data as well as a low level of hemolysis of composite cryogels based on AP and chitosan are biocompatible and can potentially be used in biomedicine. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 547-556, 2017.

Optimized method for preparation of IgG-binding bacterial magnetic nanoparticles.

In this study, the optimized method for designing IgG-binding magnetosomes based on integration of IgG-binding fusion proteins into magnetosome membrane in vitro is presented. Fusion proteins Mbb and Mistbb consisting of magnetosome membrane protein MamC and membrane associating protein Mistic from Bacillus subtilis as anchors and BB-domains of Staphylococcus aureus protein A as IgG-binding region were used. With Response Surface Methodology (RSM) the highest level of proteins integration into magnetosome membrane was achieved under the following parameters: pH 8.78, without adding NaCl and 55 s of vortexing for Mbb; pH 9.48, 323 mM NaCl and 55 s of vortexing for Mistbb. Modified magnetosomes with Mbb and Mistbb displayed on their surface demonstrated comparable levels of IgG-binding activity, suggesting that both proteins could be efficiently used as anchor molecules. We also demonstrated that such modified magnetosomes are stable in PBS buffer during at least two weeks. IgG-binding magnetosomes obtained by this approach could serve as a multifunctional platform for displaying various types of antibodies.

Isolation and identification of chitin in the black coral Parantipathes larix (Anthozoa: Cnidaria).

Until now, there is a lack of knowledge about the presence of chitin in numerous representatives of corals (Cnidaria). However, investigations concerning the chitin-based skeletal organization in different coral taxa are significant from biochemical, structural, developmental, ecological and evolutionary points of view. In this paper, we present a thorough screening for the presence of chitin within the skeletal formations of a poorly investigated Mediterranean black coral, Parantipathes larix (Esper, 1792), as a typical representative of the Schizopathidae family. Using a wide array variety of techniques ((13)C solid state NMR, Fourier transform infrared (FTIR), Raman, NEXAFS, Morgan-Elson assay and Calcofluor White Staining), we unambiguously show for the first time that chitin is an important component within the skeletal stalks as well as pinnules of this coral.

Simple method for preparation of nanostructurally organized spines of sand dollar Scaphechinus mirabilis (Agassiz, 1863).

Unique skeletal formations of marine invertebrates, including representatives of Echinodermata, have the unique potential to serve as templates for bio-inspired materials chemistry, biomimetics, and materials science. The sand dollar Scaphechinus mirabilis (Agassiz, 1983) is widely distributed in the northwest of the Pacific Ocean from southern Japan to the Aleutian Islands. This animal is the main source of naphtochinone-based substances. These compounds have recently drawn medical attention for their use as cardiological and ophthalmological drugs. Unfortunately, after extraction of the naphtochinones, the residual skeletons and spines of the sand dollars were usually discarded. Here, we report the first method for the preparation of nanostructurally organized spines of S. mirabilis, using a simple enzymatic and hydrogen peroxide-based treatment. Application of this method opens the way for development of non-wasteful environmentally clean technology of sand dollars as well-known industrial marine invertebrates.

Mineralization of the metre-long biosilica structures of glass sponges is templated on hydroxylated collagen.

The minerals involved in the formation of metazoan skeletons principally comprise glassy silica, calcium phosphate or carbonate. Because of their ancient heritage, glass sponges (Hexactinellida) may shed light on fundamental questions such as molecular evolution, the unique chemistry and formation of the first skeletal silica-based structures, and the origin of multicellular animals. We have studied anchoring spicules from the metre-long stalk of the glass rope sponge (Hyalonema sieboldi; Porifera, Class Hexactinellida), which are remarkable for their size, durability, flexibility and optical properties. Using slow-alkali etching of biosilica, we isolated the organic fraction, which was revealed to be dominated by a hydroxylated fibrillar collagen that contains an unusual [Gly-3Hyp-4Hyp] motif. We speculate that this motif is predisposed for silica precipitation, and provides a novel template for biosilicification in nature.