Poly ¦Â-hydroxybutyrate - Hydroxyvalerate (phbv), Physical Properties And Biocompatibility Study

One of the important topics studied in the tissue engineering is the material physical properties and its biocompatibility. Although many efforts have been done, an ideal tissue engineering material has not been found yet. In this experiment, the biocompatibility and biodegradability of poly (β-hydroxybutyrate-co-hydroxyvalerate) (PHBV) and the relationship between its thermal properties and degradability were studied, and the feasibility of PHBV application as a hard tissue engineering material was discussed too.1. To investigate the thermal properties and biodegradability of PHBV, PHBV material was immerged in different media and differential scanning calorimetry (DSC), thermogravimetry (TG) and scanning electron microscopy (SEM) were performed to characterize the thermal properties and biodegradability of PHBV. The experimental results suggest that PHBV degradation occurs from surface to the degraded parts of materials, and is very significant under enzymatic hydrolysis as compared to the non-enzymatic hydrolysis. But its viscosity-average molecular weight had no change during the degradation processes.2. The cytobiocompatibility of the naturally occurring, biodegradable material poly(3-hydroxybutyrate-co-hydroxyvalerate)(PHBV) was investigated with 3-(4, 5 dimethylthiazole-2-yl)-2, 5-diphenyl tertrazolium bromide (MTT) assay. BHK-21 cells of mice were implanted and cultivated in the different conditions of PHBV to determine the cell growing characteristics on the first, third and fifth day respectively. The cytobiocompatibility of PHBV was evaluated based on ISO 10993 and the Chinese national standard GB/T16886. The experimental results show that the toxicity grades of PHBV were all zero. This proved that PHBV has a good cytobiocompatibility in vitro.3. The degradation performance and tissue compatibility of PHBV films were investigated in mice to provide some experimental basis for further study in hardtissue engineering. PHBV and PLA as a control material were implanted in subcutaneous layer of 28 KM mice. Two groups local tissue and materials were removed out in K 2> 4> 6^ 8 and 13 weeks after operation. One group was observed grossly and pathological examination was made with HE staining;and another group was used to performe scanning electron microscopy (SEM). The results showed that the inflammation reaction of the mice was disappeared after 56 days in the PHBV group since the operation and its tissue compatibility is better than PLA group. The degradation rate of PHBV in vivo is not so fast, and the mice body did not make worse erosion and damage to PHBV films in 90 days.All these results showed that the poly (B-hydroxybutyrate-co-hydroxyvalerate) produced by self-laboratory has a good biocompatibility no matter in vitro or in vivo. The biodegradability of PHBV can also fulfill the requirements of hard tissue engineering.