Extreme Biomimetics: Designing of the First Nanostructured 3D Spongin-Atacamite Composite and its Application.

The design of new composite materials using extreme biomimetics is of crucial importance for bioinspired materials science. Further progress in research and application of these new materials is impossible without understanding the mechanisms of formation, as well as structural features at the molecular and nano-level. It presents a challenge to obtain a holistic understanding of the mechanisms underlying the interaction of organic and inorganic phases under conditions of harsh chemical reactions for biopolymers. Yet, an understanding of these mechanisms can lead to the development of unusual-but functional-hybrid materials. In this work, a key way of designing centimeter-scale macroporous 3D composites, using renewable marine biopolymer spongin and a model industrial solution that simulates the highly toxic copper-containing waste generated in the production of printed circuit boards worldwide, is proposed. A new spongin-atacamite composite material is developed and its structure is confirmed using neutron diffraction, X-ray diffraction, high-resolution transmission electron microscopy/selected-area electron diffraction, X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and electron paramagnetic resonance spectroscopy. The formation mechanism for this material is also proposed. This study provides experimental evidence suggesting multifunctional applicability of the designed composite in the development of 3D constructed sensors, catalysts, and antibacterial filter systems.

Novel chitin scaffolds derived from marine sponge Ianthella basta for tissue engineering approaches based on human mesenchymal stromal cells: Biocompatibility and cryopreservation.

The extraordinary biocompatibility and mechanical properties of chitinous scaffolds from marine sponges endows these structures with unique properties that render them ideal for diverse biomedical applications. In the present work, a technological route to produce "ready-to-use" tissue-engineered products based on poriferan chitin is comprehensively investigated for the first time. Three key stages included isolation of scaffolds from the marine demosponge Ianthella basta, confirmation of their biocompatibility with human mesenchymal stromal cells, and cryopreservation of the tissue-like structures grown within these scaffolds using a slow cooling protocol. Biocompatibility of the macroporous, flat chitin scaffolds has been confirmed by cell attachment, high cell viability and the ability to differentiate into the adipogenic lineage. The viability of cells cryopreserved on chitin scaffolds was reduced by about 30% as compared to cells cryopreserved in suspension. However, the surviving cells were able to retain their differentiation potential; and this is demonstrated for the adipogenic lineage. The results suggest that chitin from the marine demosponge I. basta is a promising, highly biocompatible biomaterial for stem cell-based tissue-engineering applications.

3D chitinous scaffolds derived from cultivated marine demosponge Aplysina aerophoba for tissue engineering approaches based on human mesenchymal stromal cells.

The recently discovered chitin-based scaffolds derived from poriferans have the necessary prosperities for potential use in tissue engineering. Among the various demosponges of the Verongida order, Aplysina aerophoba is an attractive target for more in-depth investigations, as it is a renewable source of unique 3D microporous chitinous scaffolds. We found these chitinous scaffolds were cytocompatible and supported attachment, growth and proliferation of human mesenchymal stromal cells (hMSCs) in vitro. Cultivation of hMSCs on the scaffolds for 7days resulted in a two-fold increase in their metabolic activity, indicating increased cell numbers. Cells cultured onto chitin scaffolds in differentiation media were able to differentiate into the chondrogenic, adipogenic and osteogenic lineages, respectively. These results indicate A. aerophoba is a novel source of chitin scaffolds to futher hMSCs-based tissue engineering strategies.

Isolation and identification of chitin from heavy mineralized skeleton of Suberea clavata (Verongida: Demospongiae: Porifera) marine demosponge.

Since the discovery of chitin in skeletal structures of sponges (Porifera) in 2007, studies on search of novel species which possess this structural aminopolysaccharide continue up today. The most potential source of chitin is suggested to be localized in the four families of sponges related to the order Verongida (Demospongiae) which nevertheless require further clarification. Here, we report for the first time the isolation and identification of α-chitin from the Suberea clavata demosponge (Aplysinidae: Verongida). Raman spectroscopy, Calcofluor White staining, chitinase test and ESI-MS techniques were used to identify chitin. We suggest that the presence of chitin within fibrous skeletons of diverse species of Verongida order, and, especially in all species of the Aplysinidae family, may be useful for the identification of novel, previously unidentified marine demosponges.

Chitin of poriferan origin and the bioelectrometallurgy of copper/copper oxide.

Chitinous scaffolds isolated from marine demosponge Ianthella basta represent novel templates for deposition of metals such as copper and copper oxides. In contrast to traditional Extreme Biomimetics methods which are based on high temperature reactions, here, we propose an alternative way based on a well-known process - electrochemical deposition or plating. This method allows production of 3D composite materials with metallic and metal oxide structures within their surfaces. For the first time chitinous scaffolds of poriferan origin, which possess a 3D network structure, were used for the copper plating. The nanocrystallites of metallic phase obtained on chitinous fibres represents replicas of the original nanofibrous substrate.

Functionalization of organically modified silica with gold nanoparticles in the presence of lignosulfonate.

It is shown that lignosulfonate (LS) can be used as an effective reducing agent for gold ions and simultaneously as a stabilizing agent for gold nanoparticles (AuNPs). When organically modified silica is introduced to the reaction mixture, most of the AuNPs grow on the surface of the silica due to hydrophobic interactions between LS and organic layers covering the solid particles. It was also found that the structure of the organic layer is crucial for the effective deposition of gold nanoparticles onto silica spheres in terms of particle size and gold content in the final SiO2-LS-AuNPs composites. Due to the hydrophobicity of the modified silica it was necessary to carry out the modification in mixed organic/aqueous solvent. The polarity of the organic co-solvent was found to have an effect on the size of the deposited Au-NPs and their quantity. The physical appearance of the obtained hybrids was analyzed by colorimetry, and their structure and composition were evaluated using transmission electron microscopy (TEM). Additionally dispersive and thermal properties were examined by dynamic light scattering (DLS) and thermogravimetry (TG), respectively. The obtained multifunctional hybrid materials exhibits remarkable catalytic activity for the reduction of C.I. Basic Blue 9 (Methylene Blue) by borohydride.

Solvothermal synthesis of hydrophobic chitin-polyhedral oligomeric silsesquioxane (POSS) nanocomposites.

Chitinous scaffolds isolated from the skeleton of marine sponge Aplysina cauliformis were used as a template for the deposition of polyhedral oligomeric silsesquioxanes (POSS). These chitin-POSS based composites with hydrophobic properties were prepared for the first time using solvothermal synthesis (pH 3, temp 80 °C), and were thoroughly characterized. The resulting material was studied using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and thermogravimetry. A mechanism for the chitin-POSS interaction after exposure to these solvothermal conditions is proposed and discussed.

Preparation of monolithic silica-chitin composite under extreme biomimetic conditions.

Chitin is a widespread renewable biopolymer that is extensively distributed in the natural world. The high thermal stability of chitin provides an opportunity to develop novel inorganic-organic composites under hydrothermal synthesis conditions in vitro. For the first time, in this work we prepared monolithic silica-chitin composite under extreme biomimetic conditions (80°C and pH 1.5) using three dimensional chitinous matrices isolated from the marine sponge Aplysina cauliformis. The resulting material was studied using light and fluorescence microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy. A mechanism for the silica-chitin interaction after exposure to these hydrothermal conditions is proposed and discussed.

Modification of chitin with kraft lignin and development of new biosorbents for removal of cadmium(II) and nickel(II) ions.

Novel, functional materials based on chitin of marine origin and lignin were prepared. The synthesized materials were subjected to physicochemical, dispersive-morphological and electrokinetic analysis. The results confirm the effectiveness of the proposed method of synthesis of functional chitin/lignin materials. Mechanism of chitin modification by lignin is based on formation of hydrogen bonds between chitin and lignin. Additionally, the chitin/lignin materials were studied from the perspective of waste water treatment. The synthetic method presented in this work shows an attractive and facile route for producing low-cost chitin/lignin biosorbents with high efficiency of nickel and cadmium adsorption (88.0% and 98.4%, respectively). The discovery of this facile method of synthesis of functional chitin/lignin materials will also have a significant impact on the problematic issue of the utilization of chitinous waste from the seafood industry, as well as lignin by-products from the pulp and paper industry.

Isolation and identification of chitin in three-dimensional skeleton of Aplysina fistularis marine sponge.

The recent discovery of chitin within skeletons of numerous marine and freshwater sponges (Porifera) stimulates further experiments to identify this structural aminopolysaccharide in new species of these aquatical animals. Aplysina fistularis (Verongida: Demospongiae: Porifera) is well known to produce biologically active bromotyrosines. Here, we present a detailed study of the structural and physico-chemical properties of the three-dimensional skeletal scaffolds of this sponge. Calcofluor white staining, Raman and IR spectroscopy, ESI-MS as well as chitinase digestion test were applied in order to unequivocally prove the first discovery of α-chitin in skeleton of A. fistularis.

Preparation of chitin-silica composites by in vitro silicification of two-dimensional Ianthella basta demosponge chitinous scaffolds under modified Stöber conditions.

Chitin is a biopolymer found in cell walls of various fungi and skeletal structures of numerous invertebrates. The occurrence of chitin within calcium- and silica-containing biominerals has inspired development of chitin-based hybrids and composites in vitro with specific physico-chemical and material properties. We show here for the first time that the two-dimensional α-chitin scaffolds isolated from the skeletons of marine demosponge Ianthella basta can be effectively silicified by the two-step method with the use of Stöber silica micro- and nanodispersions under Extreme Biomimetic conditions. The chitin-silica composites obtained at 120 °C were characterized by the presence of spherical SiO2 particles homogeneously distributed over the chitin fibers, which probably follows from the compatibility of Si-OH groups to the hydroxyl groups of chitin. The biocomposites obtained were characterized by various analytical techniques such as energy dispersive spectrometry, scanning electron microscopy, thermogravimetric/differential thermal analyses as well as X-ray photoelectron spectroscopy, Fourier transform infrared and Raman spectroscopy to determine possible interactions between silica and chitin molecule. The results presented proved that the character and course of the in vitro chitin silicification in Stöber dispersions depended considerably on the degree of hydrolysis of the SiO2 precursor.

Identification and first insights into the structure and biosynthesis of chitin from the freshwater sponge Spongilla lacustris.

This work demonstrates that chitin is an important structural component within the skeletal fibers of the freshwater sponge Spongilla lacustris. Using a variety of analytical techniques ((13)C solid state NMR, FT-IR, Raman, NEXAFS, ESI-MS, Morgan-Elson assay and Calcofluor White Staining); we show that this sponge chitin is much closer to α-chitin, known to be present in other animals, than to ß-chitin. Genetic analysis confirmed the presence of chitin synthases, which are described for the first time in a sponge. The presence of chitin in both marine (demosponges and hexactinellids) and freshwater sponges indicates that this important structural biopolymer was already present in their common ancestor.

First report on chitinous holdfast in sponges (Porifera).

A holdfast is a root- or basal plate-like structure of principal importance that anchors aquatic sessile organisms, including sponges, to hard substrates. There is to date little information about the nature and origin of sponges' holdfasts in both marine and freshwater environments. This work, to our knowledge, demonstrates for the first time that chitin is an important structural component within holdfasts of the endemic freshwater demosponge Lubomirskia baicalensis. Using a variety of techniques (near-edge X-ray absorption fine structure, Raman, electrospray ionization mas spectrometry, Morgan-Elson assay and Calcofluor White staining), we show that chitin from the sponge holdfast is much closer to α-chitin than to ß-chitin. Most of the three-dimensional fibrous skeleton of this sponge consists of spicule-containing proteinaceous spongin. Intriguingly, the chitinous holdfast is not spongin-based, and is ontogenetically the oldest part of the sponge body. Sequencing revealed the presence of four previously undescribed genes encoding chitin synthases in the L. baicalensis sponge. This discovery of chitin within freshwater sponge holdfasts highlights the novel and specific functions of this biopolymer within these ancient sessile invertebrates.

Extreme Biomimetics: formation of zirconium dioxide nanophase using chitinous scaffolds under hydrothermal conditions.

Chitinous scaffolds isolated from the skeleton of marine sponge Aplysina cauliformis were used as a template for the in vitro formation of zirconium dioxide nanophase from ammonium zirconium(iv) carbonate (AZC) under extreme conditions (150 °C). These novel zirconia-chitin based composites were prepared for the first time using hydrothermal synthesis, and were thoroughly characterized using a plethora of analytical methods. The thermostability of the chitinous 3D matrix makes it ideal for use in the hydrothermal synthesis of monoclinic nanostructured zirconium dioxide from precursors like AZC. These zirconium-chitin composites have a high potential for use in a broad range of applications ranging from synthetic catalysis to biocompatible materials for bone and dental repair. The synthetic methods presented in this work show an attractive route for producing monoclinic zirconium dioxide on a 3D biocompatible scaffold with ease.

An extreme biomimetic approach: hydrothermal synthesis of ß-chitin/ZnO nanostructured composites.

ß-Chitinous scaffolds isolated from the skeleton of marine cephalopod Sepia officinalis were used as a template for the in vitro formation of ZnO under conditions (70 °C) which are extreme for biological materials. Novel ß-chitin/ZnO film-like composites were prepared for the first time by hydrothermal synthesis, and were thoroughly characterized using numerous analytical methods including Raman spectroscopy, HR-TEM and XRD. We demonstrate the growth of hexagonal ZnO nanocrystals on the ß-chitin substrate. Our chitin/ZnO composites presented in this work show antibacterial properties against Gram positive bacteria and can be employed for development of inorganic-organic wound dressing materials.