Roxana Trusca

Porous calcium alginate–gelatin interpenetrated matrix and its biomineralization potential

Artificial bone composites exhibit distinctive features by comparison to natural tissues, due to a lack of self-organization and intimate interaction apatite-matrix. This explains the need of “bio-inspired materials”, in which hydroxyapatite grows in contact with self-assembling natural polymers. The present work investigates the function of a rational design in the hydroxyapatite-forming potential of a common biopolymer. Gelatin modified through intrinsic interactions with calcium alginate led through freeze-drying to porous hydrogels, whose architecture, constitutive features and chemistry were investigated with respect to their role on biomineralization. The apatite-forming ability was enhanced by the porosity of the materials, while the presence of alginate-reinforced Gel elastic chains, definitely favored this phenomenon. Depending on the concentration, polysaccharide chains act as “ionic pumps” enhancing the biomineralization. The mineralization-promoting effect of the peptide-polysaccharide network strictly depends on the hydrogels structural, compositional and morphological features derived from the interaction between the above mentioned two components.

Composite membranes with poly(ether ether ketone) as support and polyaniline like structure, with potential applications in fuel cells

In this paper we present the synthesis of two composite membranes with sulfonated polyether etherketone as support polymer and as conductive polymers: polyaniline and poly(p-phenylenediamine) — which has a similar structure with polyaniline. The support membranes were obtained by the phase inversion process, the conductive polymers were added by in situ polymerization into the membrane pores, and to increase the conductive properties they were doped with polystyrene sulfonic acid. The synthesized membranes were characterized by FT-IR spectroscopy, SEM, EDAX and electrochemical impedance spectroscopy.Graphical abstract

Medium chain-length polyhydroxyalkanoate copolymer modified by bacterial cellulose for medical devices

Medium chain-length polyhydroxyalkanoates (mPHAs) are flexible elastomeric biopolymers with valuable properties for biomedical applications like artificial arteries and other medical implants. However, an environmentally friendly and high productivity process together with the tuning of the mechanical and biological properties of mPHAs are mandatory for this purpose. Here, for the first time, a melt processing technique was applied for the preparation of bionanocomposites starting from poly(3-hydroxyoctanoate) (PHO) and bacterial cellulose nanofibers (BC). The incorporation of only 3 wt % BC in PHO improved its thermal stability with 25 °C and reinforced it, increasing the Youngs modulus with 76% and the tensile strength with 44%. The percolation threshold calculated with the aspect ratio of the fibers after melt processing was very low and close to 3 wt %. We showed that this bionanocomposite is able to preserve the ductile behavior during storage, no important aging being noted between 3 h and one month after compression-molding. Moreover, this study is the first to investigate the melt processability of PHO nanocomposite for tube extrusion. In addition, biocompatibility study showed no proinflammatory immune response and better cell adhesion for PHO/BC nanocomposite with 3 wt % BC and demonstrated the high feasibility of this bionanocomposite for in vivo application of tissue-engineered blood vessels.

Production and characterization of cellulose acetate – titanium dioxide nanotubes membrane fraxiparinized through polydopamine for clinical applications

The present paper introduces a study on the preparation and characterization of cellulose acetate - TiO2 nanotubes membrane. In order to be used as a hemodialysis membrane, fraxiparinized nanotubes have been incorporated into the cellulose matrix. Fraxiparine embedding was performed via strong binding ability of dopamine. Composite membrane was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and water contact angle measurement. Electrochemical impedance spectroscopy was used to correlate the morphology of composite membrane with its electrochemical properties. Mott-Schottky test proved titanium dioxide semiconductor incorporation in composite membrane. Permeation test was made to determine pure water flux. The obtained results showed that addition of nanotubes had a positive impact on membrane permeation compared with a control polymeric membrane.

In Situ Generation of Polyaniline inside Zeolite Pores for Retention of Ions and for Controlled Drug Delivery

In order to improve the capabilities of zeolites for biomedical applications, new composite materials based on polyaniline in-situ generated inside zeolite pores were developed. As precursors for polyaniline several monomers (like aniline and p-phnylenediamine) were used and different oxidant systems (like ammonium peroxodisulphate/HCl, sodium vanadate/ethylic alcohol) were studied and were used for the separation of different biological interest ions and release of antibiotics.

Development of Stabilized Magnetite Nanoparticles for Medical Applications

We report a facile method to synthesize magnetite nanoparticles with mesoporous structure by coprecipitation method using different stabilizing agents like salicylic acid, glutamic acid, and trichloroacetic acid. The stabilizing agents were used to prevent the aggregation of the magnetite nanocrystals and to obtain stable nanostructures even in the biological environment. The structure and morphology of magnetic nanocrystals were determined using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET) analysis, infrared (IR) spectra, scanning and transmission electron microscopy (SEM and TEM), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). The results reveal important differences between these magnetic nanoparticles (MNPs), which are mainly attributed to the stabilizing agents. The smallest nanoparticles were obtained in the presence of trichloroacetate ions. The mechanism of formation of these suprastructures is strongly correlated with the end functional groups of the stabilizing agent. Thus, the obtained nanoparticles are potential candidates for contrast agents as well as targeted carrier for specific diseases, especially cancer.

Applications of mesoporous silica in biosensing and controlled release of insulin

Graphical abstract Figure. No Caption available. Abstract The development of new oral insulin delivery systems could bring significant benefits to insulin‐dependent patients due to the simplicity of the method, avoidance of pain caused by parenteral administration and maintenance of optimal therapeutic levels for a longer period. However, administration of such therapeutic proteins orally remains a challenge because insulin (Ins) is a very sensitive molecule and can be easily degraded under the existing pH conditions in the stomach and intestines. Moreover, due to the large size of insulin, intestinal epithelium permeability is very low. This could be improved by immobilizing insulin in the mesoporous silica pores (MSN), acting as a shield to protect the molecule integrity from the proteolytic degradation existing in the stomach and upper part of the small intestine. Due to the high adsorption capacity of insulin, biocompatibility, ease of functionalization with various organic and/or inorganic groups, high mechanical and chemical resistance, adjustable pore size and volume, MSN is considered an ideal candidate for the development of controlled release systems that are sensitive to various stimuli (pH, temperature) as well as to glucose. Modifying MSN surfaces by coating with various mucoadhesive polymers (chitosan, alginate, etc.) will also facilitate interaction with the intestinal mucus and improve intestinal retention time. Moreover, the development of glucose‐responsive systems for achieving MSN‐based self‐regulated insulin delivery, decorated with various components serving as sensors – glucose oxidase (GODx) and phenylboronic acid (PBA) that can control the insulin dosage, avoiding overdose leading to serious hypoglycemia. MSN have also been tested for application as biosensors for glucose monitoring.

Layered Composites Based on Recycled PET/Functionalized Woven Flax Fibres

Sönmez Maria, Alexandrescu Laurentia, Nituica Mihaela, Georgescu Mihai, Gurau Florentina Dana, Ficai Denisa, Ficai Anton, Trusca Roxana, Constantinescu Doina National Research and Development Institute for Textiles and Leather–division Leather and Footwear Research Institute 93 Ion Minulescu St., Bucharest, Romania maria.sonmez@icpi.ro; laurentia.alexandrescu@icpi.ro; mihaela.nituica@icpi.ro; mihai.georgescu@icpi.ro; dana.gurau@icpi.ro Politehnica University of Bucharest, Faculty of Applied Chemistry and Material Science 1-7 Polizu St., Bucharest, Romania denisa.ficai@yahoo.ro; anton.ficai@upb.ro; truscaroxana@yahoo.com SC MONOFIL S.R.L 1 Uzinei St., Savinesti, Romania monofil.srl@gmail.com

Pressure Influence on the AlCrFeNiMn/Graphite High Entropy Composite Microhardness

During the last years, mechanical alloying technique for high entropy alloys (HEAs) has been more often approached due to the good homogenous chemical distribution and near net shape technology provided by the respectively process. A new composite material having the matrix as HEA reinforced with graphite particles was designed. The graphite particles addition in the high entropy matrix (AlCrFeNiMn) improves the particles weldability during mechanical alloying and assures a good creep behavior for the final product. The aim of this paper is to investigate the pressure influence on the microhardness as dependence of sintering parameters which can be reflected also on the microstructure. The high entropy composite was completely alloyed after 40 hours of milling. The obtained composite was pressed using different pressures values in order to investigate the pressure influence on the microhardness and microstructure. The samples were investigated using optical microscopy, scanning electron microscopy, X-rays diffraction and microhardness tests. The microhardness values for all the samples were between 300 – 700 HV.

Bioactive mesoporous silica nanostructures with anti-microbial and anti-biofilm properties

The increasing rate of antibiotic resistant bacteria associated with nosocomial infections in severely ill patients has urged the need for new antibacterial therapies. Nanostructured materials represent emerging innovative approaches to controlled delivery of different antimicrobial drugs. Delivery systems encapsulating natural compounds with antibacterial effects, such as essential oils have shown a great potential. Herein we report the development of SiO2 mesoporous nanosystems loaded with eucalyptus (EUC), orange (ORA), and cinnamon (CIN) essential oils. These systems were characterized with respect to morphology (using scanning electron microscopy, SEM, and transmission electron microscopy, TEM), porosity (by BET and TEM analysis), chemical composition (by X-ray diffraction, XRD, and Fourier transform infrared spectrometry, FTIR) and loading capacity (by thermogravimetric analysis, TGA). The anti-bacterial and anti-adherence effects were tested against clinically relevant microbial species (Staphylococcus aureus ATCC 25923; Escherichia coli ATCC 25922; and Candida albicans ATCC 10231), while the biocompatibility was evaluated by in vitro tests with L929 mouse fibroblast cells.