Hydrolytic Degradation of Biopolymer Systems Based on Poly-3-hydroxybutyrate. Kinetic and Structural Aspects (original) (raw)
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Degradation of Poly(3-hydroxybutyrate) and its Derivatives: Characterization and Kinetic Behavior
Chemistry & Chemical Technology, 2012
We focused on hydrolytic degradation kinetics at 310 and 343 K in phosphate buffer to compare PLA and PHB kinetic profiles. Besides, we revealed the kinetic behavior for copolymer PHBV (20 % of 3-hydroxyvalerate) and the blend PHB-PLA (1:1). The intensity of biopolymer hydrolysis is characterized by total weight lost and the viscosity-averaged molecular weight (MW) decrement. The degradation is enhanced in the series PHBV < PHB < PHB-PLA blend < PLA. Characterization of PHB and PHBV includes MW and crystallinity evolution (X-ray diffraction) as well as AFM analysis of PHB film surfaces before and after aggressive medium exposition. The important impact of MW on the biopolymer hydrolysis is shown.
Biodegradation kinetics of poly(3-hydroxybutyrate)-based biopolymer systems
Biochemistry (Moscow) Supplement Series B: Biomedical Chemistry, 2010
The aim of this study was to evaluate and to compare the long term kinetics curves of biodegrada tion of poly(3 hydroxybutyrate) (PHB), its copolymer poly(3 hydroxybutyrate co 3 hydroxyvalerate), and a PHB/polylactic acid composite. The total weight loss and the change of average viscosity molecular weight were used as the parameters reflecting the biodegradation degree. The rate of biodegradation was analyzed in vitro in the presence of lipase and in vivo after film implantation in animal tissues. The morphology of the PHB film surface was studied by the atomic force microscopy technique. It was shown that PHB biodegra dation involves both polymer hydrolysis and its enzymatic biodegradation. The results obtained in this study can be used for the development of various PHB based medical devices.
Mechanism and kinetics of the hydrolytic degradation of amorphous poly(3-hydroxybutyrate)
Polymer Degradation and Stability
Amorphous poly(3-hydroxybutyrate) films prepared by compression molding and solvent casting were degraded in aqueous media at different pH values. The time dependence of degradation was monitored by the measurement of weight loss, the extraction of the degradation products from the degrading sample, as well as by UV-Vis spectrophotometry and HPLC analysis of the aqueous solution. The results proved that degradation takes place mainly in the bulk of the samples and not on their surface. The overall rate of degradation depends strongly on pH; it increases with increasing pH values. Metabolite extraction and chromatography proved that degradation does not occur randomly, but with larger frequency at the end of the chains. By assuming that the hydrolysis of PHB is a SN2 type nucleofil substitution reaction, a kinetic model was proposed which describes the formation of various degradation products. The diffusion of metabolites was also accommodated into the model thus the concentration in the aqueous solution could also be predicted well. The correlation between prediction and experimental results is excellent. The model can be extended also for the description of the hydrolytic degradation of other aliphatic polyesters. 1 INTRODUCTION Poly(3-hydroxybutyrate) (PHB) is one of the most important biopolyesters from the family of polyhydroxyalkanoates which are produced by microorganisms from renewable resources [1-7]. Unlike in the synthetic polymerization of PHB, the production of the biopolymer by microbial fermentation excludes the presence of toxic products [8-10] and the hydrolytic degradation of PHB leads mainly to the monomer D-3-hydroxybutyric acid. This acid is a normal component of blood and is one of the three ketones which are
Biomaterials, 1990
The hydrolytic degradation of poly(hydroxybutyrate)-poly(hydroxyvalerate) (PHB-PHV) copolymers in the form of blends with the polysaccharides amylose, dextran, dextrin and sodium alginate, has been studied under a range of conditions (pH 2.3,7.4and 10.6 and at 37°C and 70°C). The hydrolytic degradation of the PHB-PHV copolymers was found to be dramatically affected by the presence of polysaccharides. Its progress was characterized by an initial increase in the wet weight, with concurrent decrease in the dry weight as the polysaccharides eroded from the matrix. Surface energy measurements and goniophotometry proved to be particularly useful in monitoring this stage of the degradation process. The concurrent increase in internal porosity leads to the eventual collapse of the matrix, a process which occurs, but less rapidly, in the degradation of the unblended PHB-PHV copolymers. Information obtained from molecular weight and crystallinity studies enabled a comprehensive profile of the overall degradation process to be built up. Poly( hydroxybutyrate)-poly( hydroxyvalerate) copolymers represent a useful range of potential biodegradable polymers which offer advantage in the field of biomaterials. They are produced by a bacterial synthesis process', and are now available in a wide range of molecular weights and copolymer compositions. Although a substantial body of information exists relating to the thermal degradation and processability of the poly(hydroxybutyrate) homopolymer, published information relating to the behaviour of the copolymers and in particular their hydrolytic degradation is relatively limited. In the first part of this series2, we reviewed published information on the biodegradation and hydrolysis of esterbased polymers. It was clear from this that the hydroxybutyrate-hydroxyvalerate (H B-HV) copolymers provided a considerable extension to available materials of this type. I na subsequent paper3 we reported the results of an experimental study of the hydrolytic degradation of the hydroxybutyrate homopolymer together with a series of HB-HV copolymers.
The degradation kinetics of poly(3-hydroxybutyrate) under non-aqueous and aqueous conditions
European Polymer Journal, 2002
The degradation of poly(3-hydroxybutyrate), P(3HB), was determined in two conditions namely, a non-aqueous condition of chloroform-methanol mixture in the presence of either one of the two following catalysts, 4-toluenesulphonic acid and imidazole, ancl secondly in an aqueous condition of increasing pH. From our study, a random chain scission of PHB occurred in the non-aqueous condition while the degradation of PHB in the presence of water occurred through surface hydrolysis with no change in the molecular weight. In the surface hydrolysis of the polymer, the rate was increased with higher pH 'ralues.
Biomaterials, 1989
The hydrolytic degradation of poly(hydroxybutyrate)-poly(hydroxyvalerate) (PHB-PHV) copolymers in the form of blends with the polysaccharides amylose, dextran, dextrin and sodium alginate, has been studied under a range of conditions (pH 2.3,7.4and 10.6 and at 37°C and 70°C). The hydrolytic degradation of the PHB-PHV copolymers was found to be dramatically affected by the presence of polysaccharides. Its progress was characterized by an initial increase in the wet weight, with concurrent decrease in the dry weight as the polysaccharides eroded from the matrix. Surface energy measurements and goniophotometry proved to be particularly useful in monitoring this stage of the degradation process. The concurrent increase in internal porosity leads to the eventual collapse of the matrix, a process which occurs, but less rapidly, in the degradation of the unblended PHB-PHV copolymers. Information obtained from molecular weight and crystallinity studies enabled a comprehensive profile of the overall degradation process to be built up. Poly( hydroxybutyrate)-poly( hydroxyvalerate) copolymers represent a useful range of potential biodegradable polymers which offer advantage in the field of biomaterials. They are produced by a bacterial synthesis process', and are now available in a wide range of molecular weights and copolymer compositions. Although a substantial body of information exists relating to the thermal degradation and processability of the poly(hydroxybutyrate) homopolymer, published information relating to the behaviour of the copolymers and in particular their hydrolytic degradation is relatively limited. In the first part of this series2, we reviewed published information on the biodegradation and hydrolysis of esterbased polymers. It was clear from this that the hydroxybutyrate-hydroxyvalerate (H B-HV) copolymers provided a considerable extension to available materials of this type. I na subsequent paper3 we reported the results of an experimental study of the hydrolytic degradation of the hydroxybutyrate homopolymer together with a series of HB-HV copolymers.
Biomaterials, 1990
The hydrolytic degradation of poly(hydroxybutyrate)-poly(hydroxyvalerate) (PHB-PHV) copolymers in the form of blends with the polysaccharides amylose, dextran, dextrin and sodium alginate, has been studied under a range of conditions (pH 2.3,7.4and 10.6 and at 37°C and 70°C). The hydrolytic degradation of the PHB-PHV copolymers was found to be dramatically affected by the presence of polysaccharides. Its progress was characterized by an initial increase in the wet weight, with concurrent decrease in the dry weight as the polysaccharides eroded from the matrix. Surface energy measurements and goniophotometry proved to be particularly useful in monitoring this stage of the degradation process. The concurrent increase in internal porosity leads to the eventual collapse of the matrix, a process which occurs, but less rapidly, in the degradation of the unblended PHB-PHV copolymers. Information obtained from molecular weight and crystallinity studies enabled a comprehensive profile of the overall degradation process to be built up. Poly( hydroxybutyrate)-poly( hydroxyvalerate) copolymers represent a useful range of potential biodegradable polymers which offer advantage in the field of biomaterials. They are produced by a bacterial synthesis process', and are now available in a wide range of molecular weights and copolymer compositions. Although a substantial body of information exists relating to the thermal degradation and processability of the poly(hydroxybutyrate) homopolymer, published information relating to the behaviour of the copolymers and in particular their hydrolytic degradation is relatively limited. In the first part of this series2, we reviewed published information on the biodegradation and hydrolysis of esterbased polymers. It was clear from this that the hydroxybutyrate-hydroxyvalerate (H B-HV) copolymers provided a considerable extension to available materials of this type. I na subsequent paper3 we reported the results of an experimental study of the hydrolytic degradation of the hydroxybutyrate homopolymer together with a series of HB-HV copolymers.
Biomaterials, 1987
The hydrolytic degradation of poly(hydro~butyrate) together with a series of hydro~butyrate-hydro~valerate copolymers has been studied. The effects of copolymer composition and molecular weight are presented together with the results of varying pH and temperature on the degradation rate. ~eg~dation has been monitored by weight loss and water uptake measurements together with goniophotometric, surface energy and scanning electron microscopic studies. Some comparisons with the more widely used so-called 'biodegradable' polymers, poly(glycolic acid), poly(dioxanone) and the glycolic-lactic acid (90: 10) copolymers are presented together with the effect of blood plasma on the degradation process.
Comparative in situ biodegradation studies of polyhydroxybutyrate film composites
3 Biotech, 2017
Application of polyhydroxybutyrate (PHB) to plastic industry has expanded over the last decades due to its attracting features over petro-based plastic, and therefore, its waste accumulation in nature is inevitable. In the present study, a total of four bacterial strains, viz., MK3, PN12, PW1, and Lna3, were formulated into a consortium and subsequently used as biological tool for degradation of biopolymers. The consortium was tested through λ max shifts under in vitro conditions for utilization of PHB as sole carbon source. Talc-based bioformulations of consortium were used for the degradation of PHB film composites under in situ conditions. After 9 months of incubation, the recovered samples were monitored through Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM), respectively. Analytical data, viz., changes in λ max shifts (212-219 nm), FT-IR spectra, and SEM micrographs, revealed the biodegradation potential of developed consortium against PH...