Tri-Component Hydrogel as Template for Nanocrystalline Hydroxyapatite Deposition Using Alternate Soaking Method for Bone Tissue Engineering Applications

Composite hydrogels containing apatite-like particles can act as scaffolds for osteoblast proliferation, with applications in bone tissue engineering. In this respect, porous biocompatible hydrogels were obtained from chitosan, oxidized pullulan, and PVA in different ratios. The stability of the hydrogels was ensured both by covalent bonds between aldehyde groups of oxidized pullulan and free amino groups of chitosan, and by physical bonds formed during freeze-thaw cycles and lyophilization. The deposition of calcium phosphates was performed by alternate soaking of the porous hydrogels into solutions with calcium and phosphate ions, assuring a basic pH required for hydroxyapatite formation. The mineralized hydrogels were characterized using FTIR spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis, showing that inorganic particles containing between 80 and 92% hydroxyapatite were deposited in a high amount on the pore walls of the polymeric matrix. The composition of the organic matrix influenced the crystallization of calcium phosphates and the mechanical properties of the composite hydrogels. In vitro biological tests showed that mineralized hydrogels support the proliferation of MG-63 osteoblast-like cells to a greater extent compared to pristine hydrogels.

Stable and reusable acrylic ion-exchangers. From HMIs highly polluted tailing pond to safe and clean water

The application of several ion-exchange resins (IExR) with amino and amphoteric functionalities in batch retention of heavy metal ions (HMIs) (Cu(II), Fe(II), Mn(II), Zn(II)) from mono- and multicomponent simulated waters and from real polluted water collected from tailings pond of Tarnita (Suceava, Romania) sterile dump is deeply herein explored. The tested resins exhibited high sorption capacities, as evaluated by atomic absorption spectrometry, results supported by infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The effect of pH on the IExR sorption capacity in competitive condition evidenced the optimum pH where IExR sorption efficiency is maximum. Reutilization of IExR in six consecutive sorption/desorption/regeneration cycles showed their renewable sorption properties. Wheat germination tests demonstrated that the Tarnita collected water had a high toxic effect whereas the resulted supernatant after batch sorption was nontoxic. The study shows that HMIs content after IExR sorption is under the admitted maximum level for surface water, and represents an important step on the efforts to solve the environmental problem in Tarnita area, by removing the main contaminants found in the local river water.

Hydrophobic Composites Designed by a Nonwoven Cellulose-Based Material and Polymer/CaCO3 Patterns with Biomedical Applications

Herein, we report a simple method to obtain hydrophobic surfaces by surface modification with calcium carbonate via diffusion-controlled crystallization using a cheap, versatile, and super-hydrophilic cellulose-based nonwoven material (NWM) as the substrate. To control the CaCO₃ crystal growth, the ammonium carbonate diffusion method was applied in the presence of polyanions [poly(acid acrylic), poly(2-acrylamido-2-methylpropanesulfonic acid), and a copolymer which contains 55 mol % 2-acrylamido-2-methylpropanesulfonic acid and 45 mol % acrylic acid] or nonstoichiometric polyelectrolyte complexes with polycations [poly(allylamine hydrochloride) and chitosan] on a pristine NWM and on polycation-treated surfaces. The surface morphology obtained by calcite growth under surface or environmental functional groups' influence and the hydrophilic/hydrophobic character of the composite materials were followed and compared to that of the starting material. The obtained composite materials become hydrophobic, having a contact angle in the range of 110-135°. The capacity of tetracycline sorption and release by selected modified surfaces were followed and compared to the untreated NWM. Also, the biological properties were evaluated in terms of biocompatibility, antibacterial activity, and antifouling capability.

A Proteomic Approach to Identify Zein Proteins upon Eco-Friendly Ultrasound-Based Extraction

Zein is a type of prolamin storage protein that has a variety of biomedical and industrial applications. Due to the considerable genetic variability and polyploidity of the starting material, as well as the extraction methods used, the characterization of the protein composition of zein requires a combination of different analytical processes. Therefore, we combined modern analytical methods such as mass spectrometry (MS), Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), atomic force microscopy (AFM), or Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) for a better characterization of the extracted zein. In this study, we present an enhanced eco-friendly extraction method, including grinding and sieving corn seeds, for prolamins proteins using an ultrasonic extraction methodology. The use of an ultrasonic homogenizer, 65% ethanol extraction buffer, and 710 µm maize granulation yielded the highest protein extraction from all experimental conditions we employed. An SDS PAGE analysis of the extracted zein protein mainly revealed two intense bands of approximatively 20 and 23 kDa, suggesting that the extracted zein was mostly α-zein monomer. Additionally, MS analysis revealed as a main component the α-zein PMS2 (Uniprot accession no. P24450) type protein in the maize flour extract. Moreover, AFM studies show that extracting zein with a 65% ethanol and a 710 µm granulation yields a homogeneous content that could allow these proteins to be employed in future medical applications. This research leads to a better understanding of zeins content critical for developing new applications of zein in food and pharmaceutical industries, such as biocompatible medical vehicles based on polyplexes complex nanoparticles of zein with antimicrobial or drug delivery properties.

Removal and Separation of Heavy Metal Ions from Multicomponent Simulated Waters Using Silica/Polyethyleneimine Composite Microparticles

Composite solid surfaces with high content of functional groups (FGs) are useful materials in different types of applications requiring stimuli-responsive "hard/soft" architectures, their improved properties rising from the combination of organic-inorganic parts. Among different types of weak polyelectrolytes, poly(ethyleneimine) (PEI) is of great interest in the construction of composite systems with thin layer-by-layer (LbL) organic films due to the large number of amino groups per unit mass of polymer. Herein, the spherical silica microparticles were modified with linear (L) or branched (B) PEI chains using LbL deposition of a copper complex (PEIL-Cu²⁺ or PEIB-Cu²⁺) and poly(acrylic acid) (PAA), glutaraldehyde selective cross-linking, followed by copper and PAA extraction from the multilayer. The newly formed silica/(PEIL)₁₀ and silica/(PEIB)₁₀ composites were used in batch and column sorption/desorption experiments of four heavy metal ions (Cu²⁺, Ni²⁺, Co²⁺, and Cd²⁺). In noncompetitive conditions ([FG]/Σ[M²⁺] > 9), all heavy metal ions were retained on composites, demonstrating the potential application of the prepared functional microparticles in surface water treatment. However, in competitive conditions ([FG]/Σ[M²⁺] < 9), only Cu²⁺ is sorbed in high amount (∼2.5 mmol·g^-1 PEI) on composites, with simultaneous displacement of already sorbed ions, demonstrating the solid-phase extraction and chromatographic properties of the synthesized silica/(PEIL)_n and silica/(PEIB)_n composites.