PROGRESS IN BIOMATERIALS
Year:2015 | Volume:4 | Issue:2|Papers Count:6

Biomaterials having stimuli response are interesting in the biomedical field. This paper reports about swelling response and internal structural of biomineralized (CaCO3) polyvinylpyrrolidone (PVP) carboxymethylcellulose (CMC) hydrogel having various thicknesses (0.1–0.4 mm). Samples were tested in aqueous solution using temperature ranges from 10 to 40 oC; pH varies from 4 to 9, time 60 min. In addition, an experiment was conducted in the presence of simulated biological solutions (SBS): glucose (GS), physiological fluid (PS) and urea (US) at temperature 37 oC and pH 7.5 for 180 min. It is noticed that the maximum swelling ratio reached in 30–40 oC at pH 7 in aqueous solution. Among biological fluids, the swelling ratio shows: US [PS [GS at temperature 37 oC, pH 7.5, time 150 min. The equilibrium swelling ratio of the test sample in SBS and their nonreformative apparent structure confirm that biomineralized (CaCO3) PVP–CMC hydrogel can be acclaimed for medical application like bone tissue engineering.

The effect of the solvents for silk fibroin (SF) extraction on its antimicrobial activity was studied. Extraction protocols were performed using LiBr (SFL) and Ajisawa’s reagent (CaCl2: ethanol: H2O) (SFC). The morphological and structural characteristics of the extracted SF and their composites were assessed. Corresponding bactericidal activities against Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922) and Pseudomonas aeroginosa (ATCC 27853) were performed. The resulting solutions were either casted into films or individually incorporated into composites of silver nanoparticles (NS) embedded into chitosan fragments (Cs) through c-irradiation. Films of SF, obtained by using the two solvents, as well as the final prepared composites of SF, NS and Cs were analyzed using XRD, FTIR, SEM, TEM and zeta potential at several pH values. The band gap values were calculated. The results proved that, although SFC consumed shorter gelation time, yet SFL exerted higher antibiotic activity against the tested microorganisms. Moreover, the final composites had the ability to significantly reduce the growth of these medically relevant bacteria and are, therefore, recommended as a novel natural antibacterial biomaterial for several biomedical applications.

Electro spinning technique was utilized to engineer a small-diameter (id=4 mm) tubular graft. The tubular graft was made from biocompatible and biodegradable polymers polycaprolactone (PCL) and poliglecaprone with 3: 1 (PCL: PGC) ratio. Enzymatic degradation effect on the mechanical properties and fiber morphology in the presence of lipase enzyme were observed. Significant changes in tensile strength (1.86-1.49 MPa) and strain (245–205 %) were noticed after 1 month in vitro degradation. The fiber breakage was clearly evident through scanning electron microscopy (SEM) after 4 weeks in vitro degradation. Then, the graft was coated with a collagenous protein matrix to impart bioactivity. Human umbilical vein endothelial cells (HUVECs) and aortic artery smooth muscle cells (AoSMCs) attachment on the coated graft were observed in static condition. Further, HUVECs were seeded on the lumen surface of the grafts and exposed to laminar shear stress for 12 h to understand the cell attachment. The coated graft was aged in PBS solution (pH 7.3) at 37 oC for 1 month to understand the coating stability. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) suggested the erosion of the protein matrix from the coated graft under in vitro condition.

The emerging strategy of tissue engineering for the management of end-stage organ failure and associated complications mainly relies on ECM mimicking scaffolds for neo-tissue genesis. In the current study, novel polyethylene glycol interpenetrated cross-linked hydrogel scaffold based on a co-polysaccharide (PIAC) synthesized from two marine heteropolysaccharides, alginate and chitosan, was designed. Partially cross-linked (PIAC-P) and fully cross-linked hydrogels (PIAC-F) were prepared. The physiochemical evaluations of both the hydrogels revealed the presence of alginate fraction and extensive -OH groups on the surface, sufficient water content and water holding capacity. The porosity and bulk density were also appreciable. The scaffolds were hemocompatible and were able to adsorb appreciable plasma proteins on to the surface. MTT assay on hydrogel extracts and direct contact assay showed the nontoxic effects of fibroblast cells upon contact with the hydrogel. Live/dead assay using ethidium bromide/ acridine orange cocktail on fibroblast cells grown on the hydrogels after 5 days of initial seeding displayed green nucleus revealing the non-apoptotic cells. PIAC-P hydrogels were superior to certain aspects due to the availability of free functional groups than PIAC-F where most of these groups were utilized for cross-linking. The biological evaluations confirmed the healthy being and 3D growth of fibroblasts on the porous networks of both the hydrogels. The present hydrogel can form an ECM mimic and can form a potent candidate for various tissue engineering applications.

The amphiphilic block copolymers are composed of various combinations of hydrophilic and hydrophobic block unimers. The variation in unimer ratio alters the surface aswell asmicelle-forming properties of the block copolymers. These nanoscopic micelles have the ability to encapsulate hydrophobic compounds and act as potential drug carrier. MePEG-PCL copolymers with various block lengths were synthesized by ring-opening polymerization and characterized by 1HNMR, GPC, WXRD and DSC. The number average molecular weight of the block copolymer was found to vary from 7511 to 21, 270 as determined by GPC and 1HNMR studies. The surface topology of the polymer films was determined by AFM analysis, which shows a smoother surfacewith increased MePEG contents in the block copolymers. The protein-binding assay indicates a better biocompatibility of the block copolymers in comparison to MePEG or PCL alone. The CMC of the block copolymer provides the information about micelle formations for encapsulation of hydrophobic materials and affects the in vitro release.

This article describes the synthesis of silver nanoparticles using the aqueous extract of Alternanthera sessilis as a reducing agent by sonication, espousing green chemistry principles. Biologically synthesized nanoparticle- based drug delivery systems have significant potential in the field of biopharmaceutics due to its smaller size entailing high surface area and synergistic effects of embedded biomolecules. In the present work the cytotoxic effect of biosynthesized silver nanoparticles studied by MTT assay against breast cancer cells (MCF-7 cell line) showed significant cytotoxic activity with IC50 value 3.04 mg/mL compared to that of standard cisplatin. The superior activity of the silver nanoparticles may be due to the spherical shape and smaller particle size 10-30 nm as confirmed from transmission electron microscope (TEM) analysis. The data obtained in the study reveal the potent therapeutic value of biogenic silver nanoparticles and the scope for further development of anticancer drugs.