Laura Madalina Popescu

Synthesis and characterization of acid polyurethane–hydroxyapatite composites for biomedical applications

This article aims to optimize the synthesis parameters and to establish the appropriate value of pressure for the design of polyurethane/hydroxyapatite organic matrix composites with an enhanced thermal and chemical stability. Strong interactions between Ca2+ ions and COO− groups are favoured at 60 atm. For the first time, the potential of polyurethane/hydroxyapatite material to be used as synthetic scaffold for bone cancer diagnosis was tested. The ability of polyurethane/hydroxyapatite coatings to be used as substrates for N2a cells attachment was studied using inverted optical microscopy. N2a cells presented a high birefringence and projected small prolongations of the soma comparable to control conditions, thus indicating the healthy state of the cells seeded on the composite substrates, especially in the case of composites prepared at 60–80 atm.

Development of New Ternary Nanostructured Hybrids

Ternary systems based on hydroxyl apatite-purified montmorillonite-organic polymer were synthesized in situ in hydrothermal conditions at high pressures and low temperatures. Complex nanostructured materials were obtained. The possibility of the formation of strong chemical bonds under high pressures, between organic–inorganic phases, has been investigated by Fourier Transform Infrared Spectroscopy (FT-IR). Microstructure and morphology have been investigated by High Resolution Transmission Electron Microscopy (HRTEM). Studies to understand the influence of the synthesis conditions on the final form of nanocomposite have been performed.

Comparative Study of In Situ Interactions between Maleic Anhydride Based Copolymers with Hydroxyl Apatite

A comparative study of the in situ interactions between different maleic anhydride based copolymers and calcium phosphates is presented in this paper. The ability of functional groups of the organic polymers to form under high pressure and low temperatures chemical bonds with the inorganic phase leading to improved properties of hybrid nanostructured material is discussed. The open challenges of new hybrid nanocomposites in the field of biomedical materials are evaluated. The challenge to use these nanostructured materials in medical field was evaluated by mapping the interface reactions between hybrid active layers and cells.

Evaluation of the Ability of Nanostructured PEI-Coated Iron Oxide Nanoparticles to Incorporate Cisplatin during Synthesis

Nanoparticles (NPs) have a high potential for biological applications as they can be used as carriers for the controlled release of bioactive factors. Here we focused on poly(ethylenimine) (PEI)-coated iron oxide hybrid NPs obtained by hydrothermal synthesis in high pressure conditions and evaluated their behavior in culture medium in the presence or absence of cells, as well as their ability to incorporate antitumor drug cisplatin. Our results showed that the hydrothermal conditions used for Fe-PEI NPs synthesis allowed the incorporation of cisplatin, which even increased its anti-tumor effects. Furthermore, the commonly occurring phenomenon of NPs aggregation in culture medium was exploited for further entrapment of other active molecules, such as the fluorescent dye DiI and valinomycin. The molecules bound to NPs during synthesis or during aggregation process were delivered inside various cells after in vitro and in vivo direct contact between cells and NPs and their biological activity was preserved, thus supporting the therapeutic value of Fe-PEI NPs as drug delivery tools.

Repair of the Orbital Wall Fractures in Rabbit Animal Model Using Nanostructured Hydroxyapatite-Based Implant

Cellular uptake and cytotoxicity of nanostructured hydroxyapatite (nanoHAp) are dependent on its physical parameters. Therefore, an understanding of both surface chemistry and morphology of nanoHAp is needed in order to be able to anticipate its in vivo behavior. The aim of this paper is to characterize an engineered nanoHAp in terms of physico-chemical properties, biocompatibility, and its capability to reconstitute the orbital wall fractures in rabbits. NanoHAp was synthesized using a high pressure hydrothermal method and characterized by physico-chemical, structural, morphological, and optical techniques. X-ray diffraction revealed HAp crystallites of 21 nm, while Scanning Electron Microscopy (SEM) images showed spherical shapes of HAp powder. Mean particle size of HAp measured by DLS technique was 146.3 nm. Biocompatibility was estimated by the effect of HAp powder on the adhesion and proliferation of mesenchymal stem cells (MSC) in culture. The results showed that cell proliferation on powder-coated slides was between 73.4% and 98.3% of control cells (cells grown in normal culture conditions). Computed tomography analysis of the preformed nanoHAp implanted in orbital wall fractures, performed at one and two months postoperative, demonstrated the integration of the implants in the bones. In conclusion, our engineered nanoHAp is stable, biocompatible, and may be safely considered for reconstruction of orbital wall fractures.