Biomimetic Collagen/Zn2+-Substituted Calcium Phosphate Composite Coatings on Titanium Substrates as Prospective Bioactive Layer for Implants: A Comparative Study Spin Coating vs. MAPLE.

Synthesis of biomimetic materials for implants and prostheses is a hot topic in nanobiotechnology strategies. Today the major approach of orthopaedic implants in hard tissue engineering is represented by titanium implants. A comparative study of hybrid thin coatings deposition was performed by spin coating and matrix-assisted pulsed laser evaporation (MAPLE) onto titanium substrates. The Collagen-calcium phosphate (Coll-CaPs) combination was selected as the best option to mimic natural bone tissue. To accelerate the mineralization process, Zn2+ ions were inserted by substitution in CaPs. A superior thin film homogeneity was assessed by MAPLE, as shown by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) microscopy. A decrease of P-O and amide absorbance bands was observed as a consequence of different Zn2+ amounts. A variety of structural modifications of the apatite layer are then generated, which influenced the confinement process towards the collagen template. The in-vitro Simulated Body Fluid (SBF) assay demonstrated the ability of Coll/Zn2+-CaPs coatings to stimulate the mineralization process as a result of synergic effects in the collagen-Zn2+ substituted apatite. For both deposition methods, the formation of droplets associated to the growth of CaPs particulates inside the collagen matrix was visualized. This supports the prospective behavior of MAPLE biomimetic coatings to induce mineralization, as an essential step of fast implant integration with vivid tissues.

Manufacturing nanostructured chitosan-based 2D sheets with prolonged antimicrobial activity.

The purpose of this study was to synthesize, characterize and test the antimicrobial and antifungal activity of chitosan-based hydrogels containing metal (silver - Ag) and oxide (zinc oxide - ZnO) nanoparticles (NPs) but also natural compounds such as usnic acid (UA). The two-dimensional (2D) sheets were obtained by electrospinning technique, with the aim to produce multifunctional wound dressing with regenerative and even anti-infective roles. The most important advantages of the electrospinning technique are related to the possibility of obtaining fibers with controlled morphology, usually having high specific surface and water and air penetration and the possibility of functionalizing these fibers and nets depending on the desired application. These advantages make it possible to use electrospinning for a wide range of biomedical applications, such as tissue engineering, controlled release, implantology, wound healing, and more. The obtained composite materials were characterized by infrared (IR) spectroscopy and scanning electron microscopy (SEM) and tested against common pathogens: Pseudomonas aeruginosa (Gram-negative staining), Staphylococcus aureus (Gram-positive staining) and Candida albicans (fungus).

Multifunctional materials such as MCM-41÷Fe3O4÷folic acid as drug delivery system.

In this study, MCM-41 mesoporous silica nanoparticles (NPs) and MCM-41÷Fe3O4 mesoporous silica NPs were prepared by sol-gel method using CTAB (cetyltrimethylammonium bromide) as template and TEOS (tetraethyl orthosilicate) as silica precursor in order to use these materials as drug delivery system (DDS) for different biologically active agents. The MCM-41 and MCM-41÷Fe3O4 mesoporous silica NPs were characterized using specific physico-chemical methods [transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption and desorption studies - BET (Brunauer-Emmett-Teller) method, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy], while the release studies were done by a high-performance liquid chromatography (HPLC)-modified method. The pH dependence of the delivery of folic acid from the mesoporous structures was analyzed and found that the release is pH sensitive. The lower delivery at strongly acid pH comparing with neutral/slightly alkaline pH could be beneficial because in stomach the folic acid can be destroyed.