Journal of Bioactive and Compatible Polymers

There is a need for rapid fabrication of tissue or organs with well-defined structures and functions in regenerative medicine. Two patterns of cell/matrix constructs containing hepatic cells, gelatin and fibrinogen were successfully created by automated rapid prototyping techniques and stabilized with thrombin. No apparent cell damage was found during the process. Mechanical characterization demonstrated that a 1:1 ratio gelatin/fibrin mixture had the greatest elasticity modulus and compressive strength. Microscopic and histological observations showed that hepatic cells were embedded in the gelatin/fibrinogen matrix and were proliferating. Immunostaining and biochemical analysis indicated that the embedded hepatocytes secreted albumin. Fibrin appears to be a favorable component for a gelatin based cell assembly matrix in that it is bioresorbable, easily manipulated, and supports in vitro cell functions.

Composition-graded films (CGF) of fluoroapatite (FAP) and poly(3-hydroxybutyrate- co-4-hydroxybutyrate) (PHB) were prepared via electrospinning solutions of FAP and PHB using a gradient composition of CGF. Thermal properties, mechanical properties and surface morphology of the films were investigated. Designed thermal and mechanical properties obtained by precise control of the composition gradient of the FAP/PHB CGF. The introduction of FAP in pure PHB film significantly changed the mechanical properties, such as tensile strength and extension rate of the pure PHB. Mouse fibroblast cells (L-929) were cultured on FAP/PHB uniform-films; the MTT test and cell morphology analysis indicate good biocompatibility of the modified CGF. This new method of processing makes CGF a potential candidate as an electrospinning scaffold material for tissue engineering.

The purpose of this study was to evaluate the hepatocellular compatibility and assess the inflammatory response of a novel hybrid scaffold of poly(L-lactide) (PLLA) and fibroin. The hybrid scaffold was obtained by freezing and lyophilizing a blend of fibroin microspheres and PLLA solution. FTIR and scanning electron microscopy (SEM) analysis indicated that fibroin microspheres were on the surface of the hybrid scaffold. Compared to the PLLA scaffold, SEM and laser scanning confocal microscope (LSCM) analyses showed that the human hepatocellular carcinoma HepG2 cells had spread and proliferated much more in the hybrid scaffold. The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assays indicated a greater number of cells in this hybrid scaffold. Furthermore, a mouse RAW264.7 macrophages cell line was utilized to characterize and compare the mRNA profiles of TNF-alpha using real time-polymerase chain reaction (RT-PCR). The inflammatory response of the macrophages grown in the PLLA/fibroin scaffold rapidly declined compared to those in the PLLA scaffold and reached the level of cells grown in Dulbecco's Modified Eagle Medium (DMEM). The hepatocellular compatibility and lower level of inflammatory response makes the PLLA/fibroin scaffold a promising candidate for hepatic tissue engineering.

Hydrophilic polystyrene (PS) type resins displaying excellent adsorption capacity for aromatic molecules in water were obtained by chemical modification of mesoporous cross-linked PS-type resins with a variety of hydrophilic reagents. The vinyl groups available on the surface of the resin beads were utilized as reactive sites for free radical grafting of hydrophilic moieties. Qualitative and semi-quantitative assessments of the functionalization degree were performed by Fourier transformed infrared (FTIR) spectroscopic analysis. Wetting and water uptake tests confirmed the occurrence of functionalization. The removal of an acridine virucide agent using the modified PS resins was tested under physiological conditions at pH 7.4. The virucide uptake capacity of the modified resins was in some cases almost quantitative. Antipyrogen treatment at 180°C for 8 h did not significantly affect the resin hydrophilicity, although a slight decrease in the adsorption capacity was detected. These modified resins were evaluated in hemofiltration procedures as virucide sorbents during the antiviral stage.

In this study, two composite magnetic microspheres made of tamarind gum with chitosan and artemisia seed gum with chitosan were prepared by suspension cross-linking for magnetic carrier applications. The magnetic material used in the preparation of the microspheres was prepared by precipitating FeCl3 and FeSO4 solutions in a basic medium. The morphological, thermal stability, and magnetic properties of the two composite magnetic microspheres were characterized by scanning electron microscope, magnetometry, and differential scanning calorimeter (DSC). The swelling kinetics and pH responsive behavior of the two microspheres were also studied.

In situ—forming biodegradable polymeric systems loaded with betamethasone (BTM) and betamethasone acetate (BTMA) (5, 7, and 10% (w/w)) were prepared using poly(DL-lactide-co-glycolide) (33% (w/w)), ethyl heptanoate (5% (w/w)), and N-methyl-2-pyrrolidone as biodegradable material, additive, and solvent, respectively. The effects of gamma irradiation, drug loading, and solvent removal on release profiles were evaluated. The drug release in phosphate-buffered solution (pH = 7.4, 37°C) was measured using high-performance liquid chromatography. The release profiles of irradiated and nonirradiated formulations based on BTMA showed a three-phase release pattern, whereas the pattern for BTM was biphasic. Gamma irradiation had no significant effect on the BTMA release profiles ( p>0.05). Unexpectedly, irradiation had a significant effect on release behavior of BTM ( p<0.05); also, the rate of BTM release was decreased with an increase in drug loading up to 10%. The amount of BTM that was released in the burst phase decreased by about 1.4 and 1.5 times for 7 and 10% BTM loading, respectively. The duration of BTM release was more than that of BTMA. Changes in hydrophobicity and hydrogen bonding had a strong effect on the release behavior of the two forms of BTM from the in situ—forming systems.