Hybrid green bionanocomposites based on chitosan/starch/gelatin and metallic nanoparticles for biological applications.

Multicomponent composites based on natural biopolymers: chitosan, starch and gelatin in two different ratios (0.5:1:1 and 1:1:1) were in situ crosslinked by intermolecular interactions and used as matrices for zinc oxide and magnetite fillers. The bionanocomposite films have been evaluated by spectral and microscopy methods: Fourier-Transform Infrared spectrometry (FT-IR), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) confirming the electrostatic and hydrogen bonding interactions between the components of the polymeric matrices and the inorganic fillers and the crosslinking process. AFM and SEM images showed a compact, non-porous and homogenous morphology of the hybrid films, proving a good miscibility of the blends. At lower concentrations of embedded filler, the composites were less hardened and more ductile due to the interaction with the polymeric matrix. Increased amounts of inorganic NPs led to the reduced mechanical properties of the prepared materials and increased thermal stability. The bionanocomposites revealed a similar behavior of the dielectric constant with frequency and increased values at higher temperatures. The wettability of the films' surface and the values of the water sorption capacity revealed a slight hydrophilicity of the bionanocomposites as compared with the initial matrices. The biocompatibility, evaluated by means of the surface free energy components and the interfacial tension with blood, and the hemolysis analysis demonstrated that the bionanocomposites possess a low risk of thrombosis, being promising materials for in vivo biomedical applications.

Biocompatible Self-Assembled Hydrogen-Bonded Gels Based on Natural Deep Eutectic Solvents and Hydroxypropyl Cellulose with Strong Antimicrobial Activity.

Natural deep eutectic solvents (NADES)-hydroxypropyl cellulose (HPC) self-assembled gels with potential for pharmaceutical applications are prepared. FT-IR, 1HNMR, DSC, TGA and rheology measurements revealed that hydrogen bond acceptor−hydrogen bond donor interactions, concentration of NADES and the water content influence significantly the physico-chemical characteristics of the studied gel systems. HPC-NADES gel compositions have thermal stabilities lower than HPC and higher than NADES components. Thermal transitions reveal multiple glass transitions characteristic of phase separated systems. Flow curves evidence shear thinning (pseudoplastic) behavior. The flow curve shear stress vs. shear rate were assessed by applying Bingham, Herschel−Bulkley, Vocadlo and Casson rheological models. The proposed correlations are in good agreement with experimental data. The studied gels evidence thermothickening behavior due to characteristic LCST (lower critical solution temperature) behavior of HPC in aqueous systems and a good biocompatibility with normal cells (human gingival fibroblasts). The order of antibacterial and antifungal activities (S.aureus, E.coli, P. aeruginosa and C. albicans) is as follows: citric acid >lactic acid > urea > glycerol, revealing the higher antibacterial and antifungal activities of acids.

Hydroxypropyl Cellulose/Pluronic-Based Composite Hydrogels as Biodegradable Mucoadhesive Scaffolds for Tissue Engineering.

Recently, the development of new materials with the desired characteristics for functional tissue engineering, ensuring tissue architecture and supporting cellular growth, has gained significant attention. Hydrogels, which possess similar properties to natural cellular matrixes, being able to repair or replace biological tissues and support the healing process through cellular proliferation and viability, are a challenge when designing tissue scaffolds. This paper provides new insights into hydrogel-based polymeric blends (hydroxypropyl cellulose/Pluronic F68), aiming to evaluate the contributions of both components in the development of new tissue scaffolds. In order to study the interactions within the hydrogel blends, FTIR and 1HNMR spectroscopies were used. The porosity and the behavior in moisture medium were highlighted by SEM and DVS analyses. The biodegradability of the hydrogel blends was studied in a simulated biological medium. The hydrogel composition was determinant for the scaffold behavior: the HPC component was found to have a great influence on the BET and GAB areas, on the monolayer values estimated from sorption-desorption isotherms and on mucoadhesivity on small intestine mucosa, while the Pluronic F68 component improved the thermal stability. All blends were also found to have good mechanical strength and increased biocompatibility on the NHDF cell line. Based on their particular compositions and increased mucoadhesivity on small intestine mucosa, these polymeric blends could be effective in the repair or recovery of damaged cell membranes (due to the contribution of Pluronic F68) or in control drug-delivery intestinal formulations.

Mucoadhesive and Antimicrobial Allantoin/ß Cyclodextrins-Loaded Carbopol Gels as Scaffolds for Regenerative Medicine.

Allantoin and its ß-cyclodextrin and hydroxypropyl-ß-cyclodextrin inclusion complexes 1:1 have been used to prepare carbopol-based mucoadhesive gels. The gelation process occurred by adjustment with glycerol 10% in the presence of triethanolamine. The structural features induced by the presence of allantoin and the corresponding ß-cyclodextrins inclusion complexes have been first investigated by infrared spectroscopy highlighting strong interactions within the gels network and ideal crosslinks for the self-healing behavior. The hydrophilicity of the gels was investigated by the determination of the surface tension parameters and the free energy of hydration. The interfacial free energy values indicated prolonged biocompatibility with blood. The gels-water molecule interactions in terms of sorption, permeability, and diffusion coefficients were evaluated by dynamic vapor sorption analysis. The self-assembly process through intermolecular H-bonding, the high hydrophilicity, the mechanical performance, the hydrolytic stability in simulated biological media, the biocompatibility with normal human dermal fibroblast (NHDF) cells, the mucoadhesivity and antimicrobial activity on selected microorganism species (S. Aureus and C. albicans) of the allantoin-based gels recommend them as promising scaffold alternatives in regenerative medicine.

Blends of sodium deoxycholate-based poly(ester ether)urethane ionomer and hydroxypropylcellulose with mucosal adhesiveness.

New mucoadhesive blends of sodium deoxycholate-based poly(ester ether)urethane ionomer (PU) and hydroxypropyl cellulose (HPC) are prepared. The presence of the intermolecular interactions between the polymeric components has been investigated by FTIR spectroscopy indicating their miscibility in the solid phase. DSC studies also revealed a single glass transition of the blends, which is indicative of miscibility of PU and HPC in the amorphous phase. The amount of HPC in the blends influences strongly the physicochemical and mucoadhesion/bioadhesion properties. It was found that the value of area attributed to ordered hydrogen bonding (FTIR), the onset temperature values of thermal degradation in N2 flow (TG/DTG), the values of the sorption capacity (Dynamic Vapor Sorption-DVS), the values of the apparent viscosity (rheological measurements) and mucoadhesion/bioadhesion properties increased by increasing the HPC content in the blends. Complex viscosity revealed shear thinning behavior for all the studied solutions evidencing the contributive role of polymer viscoelasticity on mucoadhesion. It was found that both G' and G" increase with an increase in angular frequency and G">G' which is characteristic for liquid-like (sol state) behavior for all blended solutions and this behavior is helpful in the adhesion with mucosa surface. Mucoadhesion of PU/HPC blends was assessed in the stomach mucosa at pH 2.6 and 37 °C. Bioadhesion test was performed at pH 7.4 and 37 °C and revealed a stronger interaction of PU/HPC blends with cellulose membrane than with stomach mucosa. The similar nature of the HPC and cellulose membrane determines additional adhesion forces and implicity high adhesion properties. The HPC component increases the hydrophilicity of the blends as DVS analysis revealed, but also leads to hydrolytic degradation. FTIR spectroscopy analysis was used to evaluate the hydrolytic stability in acid (pH 2.6) and slightly alkaline (pH 7.4) PBS media and a mechanism of degradation has been proposed.

Design, Preparation and Evaluation of HPMC-Based PAA or SA Freeze-Dried Scaffolds for Vaginal Delivery of Fluconazole.

PURPOSE: Aim of this work was preparation of bioadhesive gel formulations based on Hydroxypropyl methylcellulose (HPMC), Poly(acrylic acid) (PAA) or Sodium alginate (SA) loaded with anise/fluconazole ß-cyclodextrin inclusion complexes in 1:2 and 1:3 ratios intended for vaginal applications. METHODS: Freeze-drying method was effectively utilized and superporous morphology was obtained. The superporous morphology of the lyophilized gels, dynamic water vapor sorption measurements, drug release kinetics studies and their antimicrobial activities are presented. RESULTS: HPMC content influences especially the sorption/desorption behaviour of HPMC-based PAA gels and the morphology of the gel formulations with fluconazole/ß-cyclodextrin inclusion complexes, due to the interactions among the gel networks absorbing water molecules. It was found that fluconazole release kinetics correspond to quasi-Fickian, Fickian diffusion and non-Fickian mechanisms for the studied hydrogels. The tested vaginal formulations with ß-cyclodextrin inclusion complexes exhibited selectivity toward S. aureus ATCC 25923 and all tested Candida strains in comparison with the gel formulation without ß-cyclodextrin. CONCLUSIONS: The fluconazole/ß cyclodextrin inclusion complexes ensure a controlled release of fluconazole over a few days, the highest amount of drug release (92%) being observed after 43 h. These bioadhesive gel formulations could be very promising topical alternative for treatment of vaginal fungal infections.

Formulation and evaluation of anise-based bioadhesive vaginal gels.

Various formulations of anise-based bioadhesive gels are prepared. Freeze-drying method was successfully employed and superporous scaffolds were obtained. The resulting porous microarchitectures are strongly influenced by the composition of hydrogel formulations and temperature of freezing. Anise-based hydrogels frozen in liquid nitrogen and lyophilized generate regular assembly of polyhedral pores. For Carbopol 934-based hydrogels it was determined G'>G'' for whole tested strain amplitude range indicating solid-like behaviour due to their dense network and entanglement and interaction through hydrogen bonds and van-der Waals forces. For sodium alginate-based hydrogels it was determined G''>G' for whole tested strain amplitude range accompanied by the extended linear viscoelastic region indicating liquid-like behaviour due to the formation of a stable "pseudo-gel" structure. Biocompatibility features of tested hydrogels were evaluated by contact angle measurements and determination of surface tension parameters. It was found that all anise-based hydrogel formulations manifest modest activity against S. aureus and S. lutea and no activity against tested Gram negative bacteria. Carbopol 934-based hydrogels containing anise exhibit antifungal activity against C. albicans, C. glabrata and C. Parapsilosis.

Polyurethane/ß-cyclodextrin/ciprofloxacin composite films for possible medical coatings with antibacterial properties.

Polyurethane/ß-cyclodextrin/ciprofloxacin composite films have been prepared and structural and morphological behaviours reveal the progressive incorporation of the drug ciprofloxacin into polyurethane backbones. Spectral changes such as frequency shifts, band broadening and changes in the intensity are indicative of drug-polyurethane interactions. X-ray powder diffraction experiments demonstrate that ciprofloxacin retains its crystallinity in the polyurethane matrix. Electron microscopy and mercury porosimetry reveal open and interconnected macroporous pore morphology for the as-prepared polyurethane-drug films. Antimicrobial activity was evaluated by the agar disc diffusion method and the ciprofloxacin-polyurethane films demonstrate their potency as antibacterial medical systems. However, the ciprofloxacin-polyurethane films do not reveal antifungal properties.

Evaluation of polyurethane based on cellulose derivative-ketoprofen biosystem for implant biomedical devices.

A polyether-urethane based on polytetrahydrofuran containing hydroxypropyl cellulose for biomedical applications was tested for its biocompatibility. Ketoprofen was incorporated (3% and 6%) in the polyurethane matrix as an anti-inflammatory drug. Dynamic vapour sorption method was employed for testing the water sorption/desorption behaviour of these materials with the determination of the surface isotherms, surface parameters and the kinetic curves of sorption/desorption processes. Cytotoxicity testing in vitro for quantifying cell proliferation was employed, and the results evidence noncytotoxicity for the studied polyurethane-drug systems. In vivo biocompatibility study was performed on 200 g weight male rats. It was found that after implantation of the polyether-urethane samples a reduced acute inflammation occurred, especially for polyurethane samples with added ketoprofen.

Thermal, dynamic mechanical, and dielectric analyses of some polyurethane biocomposites.

Polymer biocomposites based on segmented poly(ester urethane) and extracellular matrix components have been prepared for the development of tissue engineering applications with improved biological characteristics of the materials in contact with blood and tissues for long periods. Thermal, dynamical, and dielectrical analyses were employed to study the molecular dynamics of these materials and the influence of changing the physical network morphology and hydrogen bond interactions accompanied by phase transitions, interfacial effects, and polarization or conductivity. All phenomena that concur in the tested materials are evaluated by cross-examination of the dynamic mechanical characteristic properties (storage modulus, loss modulus, and loss factor) and dielectric properties (relative permittivity, relative loss factor, and loss tangent) as a function of temperature. Comparative aspects were elucidated by calculating the apparent activation energies of multiplex experiments.

Segmented biopolyurethanes for medical applications.

Polyurethanes are one of the most popular groups of biomaterials applied for medical devices. Their segmented block copolymeric character endows them a wide range of versatility in terms of tailoring their physical properties, blood and tissue compatibility. Polyester- and polyether-urethanes have been modified with hydroxypropyl cellulose aiming the change of their surface and bulk characteristics to confer them biomaterial qualities. In this respect, dynamic contact angle measurements, dynamic mechanical analyses accompanied by mechanical testing have been done. Platelet adhesion test has been carried out in vitro and the use of hydroxypropyl cellulose in the polyurethane matrix reduces the platelet adhesion and therefore recommends them as candidates for biocompatible materials.

Surface characterization of biopolyurethanes based on cellulose derivatives.

Surface tension parameters and surface morphology of biopolyurethanes based on cellulose derivatives thin films, before and after HF cold plasma treatment has been investigated. Calculations are based on the geometric mean approach of Owens and Wendt, Rabel and Kälble, on the Lifshitz-van der Waals acid/base approach of van Oss and co-workers and on the theoretical methods involving quantitative structure-property relationship. For all the investigated samples the polar component contributes significantly to the total surface tensions, as due to the large electron donor interactions. HF cold plasma treatment modifies the surface energy of biopolyurethanes by changing their surface polarity and hydrophilicity. The hydrophilic/hydrophobic balance was studied by means of the free energy of hydration between the biomaterial film and water. The protein adsorption tests of fibrinogen were effected to evaluate the applicability of these biopolyurethanes as biomedical thromboresistant devices.

Characterization by fourier transform infrared spectroscopy (FT-IR) and 2D IR correlation spectroscopy of PAMAM dendrimer.

FT-IR and 2D correlation spectroscopy were employed to study the microstructural changes occurring during phase transitions of a liquid crystal poly(amidoamine) codendrimer (PAMAM (L1)16(L2)16) generation 3, functionalized on the terminal groups by one-chain promesogenic calamitic units (4-(4'-decyloxybenzoyloxy)salicylaldehyde (L1)) and two-chain promesogenic calamitic units (4-(3',4'-didecyloxybenzoyloxy)salicylaldehyde (L2)). Spectral modifications associated with molecular conformation rearrangements allowing for molecular shape change on going from a liquid-crystalline organization to another were found. The transition temperatures were calculated, and they are in good agreement with the DSC data. Spectral analysis gives evidence of the LC phase transitions and to an additional transition associated with the existence of conformers. Various types of hydrogen bonding have been established.