Vera Balan

Crosslinked hydrogels based on biological macromolecules with potential use in skin tissue engineering

Zero-length crosslinked hydrogels have been synthesized by covalent linking of three natural polymers (collagen, hyaluronic acid and sericin), in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide. The hydrogels have been investigated by FT-IR spectroscopy, microcalorimetry, in vitro swelling, enzymatic degradation, and in vitro cell viability studies. The obtained crosslinked hydrogels showed a macroporous structure, high swelling degree and in vitro enzymatic resistance compared to uncrosslinked collagen. The in vitro cell viability studies performed on normal human dermal fibroblasts assessed the sericin proliferation properties indicating a potential use of the hydrogels based on collagen, hyaluronic acid and sericin in skin tissue engineering.

Upon synthesis of a polymeric matrix with pH and temperature responsiveness and antioxidant bioactivity based on poly(maleic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane) derivatives.

Poly(maleic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane), acquired through radical polymerization, was synthesized with the aim to prepare an alternant copolymer with precise placement of functional groups along the polymer backbones. The new structure owing to the suitable and specific functionalities is anticipated to be used as reactive polymer to link bioactive compounds via maleic anhydride moiety. The copolymer was improved in its functionality by maleic anhydride ring opening with different amounts of erythritol in order to confer antioxidant characteristics to the polymeric structure. The chemical structure of the new prepared polymers was confirmed by FTIR and (1)H NMR spectra, and the polymers were also characterized from the viewpoint of their thermal stability. The dual sensitivity of the polymeric structure, at temperature and pH, was evaluated by determining the hydrodynamic radius and zeta potential in interdependence with the environment conditions. The polymer morphology was investigated by SEM. The antioxidant character was evaluated measuring the scavenger properties of the functionalized copolymer with erythritol against the 2,2-diphenyl-1-picrylhydrazyl radicals. The acute toxicity investigation, realized in vivo for the copolymer and the derivatives, allows the inclusion of the compounds into the group of moderately toxic accordingly to Hodge and Sterner toxicity scale owing to the lethal dose 50 determined values.

Porous magnetic scaffolds for bone tissue engineering and regeneration

A precipitation process of the calcium phosphates from precursors on a biopolymeric matrix based on chitosan, collagen, sodium hyaluronate, containing magnetic nanoparticles has been used to achieve porous magnetic scaffolds for bone tissue engineering. Porosity is one of the most important properties of a scaffold manufactured for applications in bone tissue engineering and regeneration and has been studied using Scanning Electron Microscopy (SEM). Fourier Transform Infrared Microscopy (FTIR) has been used to study the chemical structure of the scaffolds. The porosity of the scaffolds influences the retention of simulated body fluids, in vitro degradation and also in vitro biocompatibility.

Preparation, Characterization and Preliminary Evaluation of Magnetic Nanoparticles based on Biotinylated N-palmitoyl Chitosan

Magnetic nanoparticles based on biotinylated N-palmitoyl chitosan and magnetite have been prepared via ionic gelation method. Dynamic light scattering results showed that magnetic nanoparticles average size is dependent on a series of parameters: polymer concentration, weight ratio polymer/cross-linking agent and the stirring speed. In vitro release studies have shown the ability of magnetic nanoparticles to release an antitumoral drug (Doxorubicin) for a period of 6 hours whereas in vitro cytotoxicity tests indicated that the prepared magnetic nanoparticles exhibited anti-proliferative effects on tumoral cells (MCF-7 cell line human breast adenocarcinoma), up to the lowest tested concentration. Fluorescence microscopy revealed that magnetic nanoparticles (BMN6-DOX) were internalized in MCF-7 cells. These properties indicate the potential application as targeted drug delivery system for breast cancer treatment.

Magnetic Nanoparticles Inclusion into Scaffolds Based on Calcium Phosphates and Biopolymers for Bone Regeneration

Considering its functions (support, protection, assisting in movement and storage of minerals), the bone is an essential organ for the human body and the bone trauma/damages have a great impact on the human body functionality. For that reason a variety of biomaterials are studied for potential applications in bone regeneration or substitution. Bone substitution materials, with similar chemical composition to that of natural bone, and specifically those obtained by processes which mimic the natural bone formation in vivo, has been shown to be among the best. In this study, using a process of co-precipitation of calcium phosphate precursors on a mixture of biopolymers (chitosan, collagen, hialuronic acid) and magnetic nanoparticles (magnetite functionalized with chitosan), biodegradable biomimetic scaffolds have been obtained. In order to study their chemical structure, the biodegradable scaffolds have been characterized by Fourier Transform Infrared Spectroscopy (FTIR). The morphology of the biodegradable scaffolds, studied using scanning electron microscopy (SEM) indicated a macroporous morphology, which influenced the retention of simulated biological fluids. A direct relationship between the scaffolds’ degradation rate and the concentration of the polymeric phase has been observed. The in vitro cytocompatibility tests indicate that the prepared scaffolds are biocompatible and assure and adequate mediums for osteoblasts.

Bio-inspired calcium phosphates-biopolymer scaffolds with inclusions of SPIONs for bone tissue regeneration

Magnetic scaffolds have been obtained using a process of precipitation of calcium phosphates from precursors (CaCl2 and NaH2PO4) on a mixture of biopolymers (chitosan, collagen, sodium hyaluronate) and SPIONs (magnetite coated with chitosan). Three-dimensional porous structures of the magnetic scaffolds has been revealed by Scanning Electron Microscopy (SEM) data and Fourier Transform Infrared Spectroscopy (FTIR) indicated that peaks from the three biopolymers, calcium phosphates and magnetic nanoparticles are present. The retention of simulated body fluids is dependent on the scaffolds morphology and the in vitro enzymatic degradation rate is strongly correlated with the presence of organic phase. The interaction of the magnetic scaffolds with osteoblast cells has demonstrated that they have good cytocompatibility.

Design and characterization of biotinylated magnetic nanocapsules for breast cancer applications

Biotinylated nanostructures have been prepared by immobilization of biotin on the surface of doxorubicin-loaded magnetic nanocapsules based on N-palmitoyl chitosan and magnetite, via carbodiimide chemistry, in the presence of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide. The structure of biotinylated magnetic nanocapsules has been confirmed by Fourier transform infrared (FT-IR) spectroscopy. Dynamic light scattering measurements showed that biotinylated nanocapsules exhibit a hydrodynamic mean diameter of about 250 nm and negative zeta potential. Biotinylated nanocapsules exhibited cytotoxic effects on MCF-7 cell line human breast adenocarcinoma and good redispersion ability in glucose solution, suitable characteristics for future breast cancer chemotherapy applications.

Upon Synthesis of Poly(N-isopropylacrylamide-co-2-dimethyl-aminoethyl methacrylate-co-itaconic acid) Copolymers as Matrix Ensuring Intramolecular Strategies for Further Coupling Applications

The study presents a set of copolymers synthesis based on N-isopropylacrylamide, 2-dimethylaminoethyl methacrylate and itaconic acid comonomers found in different gravimetric ratio, acquired through polymerization in water in the presence of ammonium persulfate as radical initiator. The purpose was to prepare polymeric structure with dual sensitivity to temperature and pH respectively, and able as well to ensure intramolecular strategies for coupling applications of inorganic or bioactive compounds. The polymers composition was confirmed by FTIR and 1 H-NMR spectra. The thermal stability of the polymeric compounds was evaluated, and SEM investigations of the polymer morphology are also presented. The polymers dispersions were characterized from the viewpoint of their hydrodynamic radius, zeta potential and conductivity.

Functionalized superparamagnetic nanoparticles as versatile carriers for targeted antioxidant enzyme therapy

Functionalized superparamagnetic nanoparticles based on poly (succinimide)- b -poly(ethylene glycol) and magnetite have been obtained by immobilization of superoxide dismutase via activation with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDAC). Dynamic light scattering measurements showed that hydrodynamic mean diameters of the functionalized particles were about 700 nm. These particles exhibit a superparamagnetic behaviour and high magnetic saturation, good cell biocompatibility and enzymatic activity, characteristics that recommend them in application as versatile carriers for targeted antioxidant enzyme therapy.

Synthesis and characterization of magnetic nanoparticles based on N-palmitoyl-chitosan with potential applications in cancer theranostics

A novel magnetic carrier has been prepared by ionic gelation of N-palmitoyl chitosan with sodium tripolyphosphate, in the presence of magnetite. N-palmitoyl chitosan structure has been confirmed by proton nuclear magnetic resonance (1H-NMR) and Fourier transform infrared (FT-IR) spectroscopy. Dynamic light scattering measurements showed that magnetic nanoparticles have a hydrodynamic mean diameter of about 150 nm and positive zeta potential. The particles are characterized by high magnetic saturation, superparamagnetic behaviour and exhibit the ability to incorporate a chemoterapeutic agent (Doxorubicin), properties that can be further exploited in cancer theranostics.