Non-degradable Polymers Research Articles

Tissue Integration of Polyacrylamide Hydrogel: An Experimental Study of Periurethral, Perivesical, and Mammary Gland Tissue in the Pig

BACKGROUND Polyacrylamide hydrogel (PAAG) is a nondegradable water-based polymer with high viscoelasticity. The gel is used as a tissue filler, the only risk being prolonged infection with anaerobic, contaminating microorganisms if not treated early with broad-spectrum antibiotics. OBJECTIVE With silicone gel as reference, PAAG tissue integration and migration was studied in a longitudinal study of the pig. MATERIALS AND METHODS Forty-one pigs were used. PAAG and silicone gel were injected into mammary tissue, and PAAG was injected into urethral or bladder wall or the anal canal. Tissues and regional lymph nodes were examined at 1, 1(1/2), 3, 3(1/2), 6, 12, and 14 months, and other lymph nodes and organs were examined at 1, 6, 12, and 14 months. RESULTS PAAG was invaded by macrophages and giant cells that were gradually replaced by a network of fibrous tissue. Silicone gel was seen inside these cells or as large vacuoles, surrounded by a fibrous capsule. Regional lymph nodes contained PAAG only at 1 1/2 months and silicone gel at 12 months. CONCLUSION PAAG is a stable, viscoelastic bulking agent, which unlike silicone gel is slowly integrated within its host tissue via a thin fibrous network. Long-term risk of fibrosis and migration is minimal.

Nanoparticle: Drug delivery system for cancer therapy

Nanoparticle has emerged as a promising strategy for the efficient delivery of drugs used in the treatment of cancer by avoiding the reticuloendothelial system, utilizing the enhanced permeability and retention effect and tumor-specific targeting. Delivery methods using nanoparticle are highlighted including both degradable and non-degradable polymers. The preparation techniques include emulsion polymerization, micelle polymerization, desolvation of macromolecule, and emulsion-solvent evaporation methods.The particle size of the polymeric nanoparticle is in the nanometer range (10-1000 nm) and is dependent on the method of preparation employed.

La thérapie cellulaire du cartilage : bases cellulaires et moléculaires

The destruction of articular cartilage represents the outcome of most inflammatory and degenerative rheumatic diseases and leads to severe disability. Articular cartilage being unable to repair spontaneously, alterations of the joint surface often results in end-stage osteoarthritis, requiring surgical intervention and total joint replacement. This makes damaged tissues repair a major challenge in our aging society. Cartilage harbors only one cell type, the chondrocyte, which synthesizes and secretes specific matrix proteins such as type II collagen and high molecular weight proteoglycans. Matrix proteins are responsible for the conservation of the chondrocyte phenotype and the maintenance of the mechanical functions of cartilage. Development of therapeutic strategies for cartilage repair should thus comprise not only the replacement of lost cartilage cells but also that of extracellular matrix with cartilage-like properties. Different protocols are under investigation. The most commonly employed materials include transplantation of autologous osteochondral tissue. More recently, cell-based therapies using autologous mature chondrocytes or pre-chondrogenic stem cells have drawn particular attention. Tissue-engineering procedures represent the actual trend in cartilage repair. This approach combines biodegradable polymeric three-dimensional matrixes and isolated prechondrogenic stem cells. The cells are seeded within the biocompatible matrix and then implanted into the joint. Numerous non-degradable and degradable polymers, which efficiently "mimic" the natural surroundings of cartilage cells, are currently under investigation.

Tissue-engineered blood vessels with endothelial nitric oxide synthase activity

Nondegradable synthetic polymer vascular grafts used in cardiovascular surgery have shown serious shortcomings, including thrombosis, calcification, infection, and lack of growth potential. Tissue engineering of vascular grafts with autologous stem cells and biodegradable polymeric materials could solve these problems. The present study is aimed to develop a tissue-engineered vascular graft (TEVG) with functional endothelium using autologous bone marrow-derived cells (BMCs) and a hybrid biodegradable polymer scaffold. Hybrid biodegradable polymer scaffolds were fabricated from poly(lactide-co-epsilon-caprolactone) (PLCL) copolymer reinforced with poly(glycolic acid) (PGA) fibers. Canine bone marrow mononuclear cells were induced in vitro to differentiate into vascular smooth muscle cells and endothelial cells. TEVGs (internal diameter: 10 mm, length: 40 mm) were fabricated by seeding vascular cells differentiated from BMCs onto PGA/PLCL scaffolds and implanted into the abdominal aorta of bone marrow donor dogs (n = 7). Eight weeks after implantation of the TEVGs, the vascular grafts remained patent. Histological and immunohistochemical analyses of the vascular grafts retrieved at 8 weeks revealed the regeneration of endothelium and smooth muscle and the presence of collagen. Western blot analysis showed that endothelial nitric oxide synthase (eNOS) was expressed in TEVGs comparable to native abdominal aortas. This study demonstrates that vascular grafts with significant eNOS activity can be tissue-engineered with autologous BMCs and hybrid biodegradable polymer scaffolds.

Biodegradation of Agricultural Plastic Films: A Critical Review

The growing use of plastics in agriculture has enabled farmers to increase their crop production. One major drawback of most polymers used in agriculture is the problem with their disposal, following their useful life-time. Non-degradable polymers, being resistive to degradation (depending on the polymer, additives, conditions etc) tend to accumulate as plastic waste, creating a serious problem of plastic waste management. In cases such plastic waste ends-up in landfills or it is buried in soil, questions are raised about their possible effects on the environment, whether they biodegrade at all, and if they do, what is the rate of (bio?)degradation and what effect the products of (bio?)degradation have on the environment, including the effects of the additives used. Possible degradation of agricultural plastic waste should not result in contamination of the soil and pollution of the environment (including aesthetic pollution or problems with the agricultural products safety). Ideally, a degradable polymer should be fully biodegradable leaving no harmful substances in the environment. Most experts and acceptable standards define a fully biodegradable polymer as a polymer that is completely converted by microorganisms to carbon dioxide, water, mineral and biomass, with no negative environmental impact or ecotoxicity. However, part of the ongoing debate concerns the question of what is an acceptable period of time for the biodegradation to occur and how this is measured. Many polymers that are claimed to be ‘biodegradable’ are in fact ‘bioerodable’, ‘hydrobiodegradable’, ‘photodegradable’, controlled degradable or just partially biodegradable. This review paper attempts to delineate the definition of degradability of polymers used in agriculture. Emphasis is placed on the controversial issues regarding biodegradability of some of these polymers.

A biodegradable vascularizing membrane: A feasibility study

Regenerative medicine and in vivo biosensor applications require the formation of mature vascular networks for long-term success. This study investigated whether biodegradable porous membranes could induce the formation of a vascularized fibrous capsule and, if so, the effect of degradation kinetics on neovascularization. Poly( l-lactic acid) (PLLA) and poly( dl-lactic-co-glycolic) acid (PLGA) membranes were created by a solvent casting/salt leaching method. Specifically, PLLA, PLGA 75:25 and PLGA 50:50 polymers were used to vary degradation kinetics. The membranes were designed to have an average 60 μm pore diameter, as this pore size has been shown to be optimal for inducing blood vessel formation around nondegradable polymer materials. Membrane samples were imaged by scanning electron microscopy at several time points during in vitro degradation to assess any changes in pore structure. The in vivo performance of the membranes was assessed in Sprague–Dawley rats by measuring vascularization within the fibrous capsule that forms adjacent to implants. The vascular density within 100 μm of the membranes was compared with that seen in normal tissue, and to that surrounding the commercially available vascularizing membrane TheraCyte. The hemoglobin content of tissue containing the membranes was measured by four-dimensional elastic light scattering as a novel method to assess tissue perfusion. Results from this study show that slow-degrading membranes induce greater amounts of neovascularization and a thinner fibrous capsule relative to fast degrading membranes. These results may be due both to an initially increased number of macrophages surrounding the slower degrading membranes and to the maintenance of their initial pore structure.

Aromatic Copolyester-based Nano-biocomposites: Elaboration, Structural Characterization and Properties

Biodegradable polymers are one of the most promising ways to replace non-degradable polymers. But, to be a real alternative to classical synthetic polymers and find applications, biopolymer (biodegradable polymer) properties have to be enhanced. Nano-biocomposites, which are obtained by incorporation of nanofillers into a biomatrix, are an interesting way to achieve these improvements. Modified and unmodified montmorillonites have been introduced into a biodegradable aromatic copolyester, poly(butylene adipate-co-terephthalate) (PBAT). Structural characterization, thermal and mechanical tests have been carried out to understand better the relations between the nanofillers structuring and the final nano-biocomposite properties. Main results show that clay incorporation and the obtained intercalated structures improve PBAT properties (enhanced thermal stability, increased stiffness) and thus may increase the attractiveness of this biopolymer.

Bioengineered Strategies for Spinal Cord Repair

This article reviews bioengineered strategies for spinal cord repair using tissue engineered scaffolds and drug delivery systems. The pathophysiology of spinal cord injury (SCI) is multifactorial and multiphasic, and therefore, it is likely that effective treatments will require combinations of strategies such as neuroprotection to counteract secondary injury, provision of scaffolds to replace lost tissue, and methods to enhance axonal regrowth, synaptic plasticity, and inhibition of astrocytosis. Biomaterials have major advantages for spinal cord repair because of their structural and chemical versatility. To date, various degradable or non-degradable biomaterial polymers have been tested as guidance channels or delivery systems for cellular and non-cellular neuroprotective or neuroregenerative agents in experimental SCI. There is promise that bioengineering technology utilizing cellular treatment strategies, including Schwann cells, olfactory ensheathing glia, or neural stem cells, can promote repair of the injured spinal cord. This review is divided into three parts: (1) degradable and non-degradable biomaterials; (2) device design; and (3) combination strategies with scaffolds. We will show that bioengineering combinations of cellular and non-cellular strategies have enhanced the potential for experimental SCI repair, although further pre-clinical work is required before this technology can be translated to humans.

Mechanical Interlocking of Engineered Cartilage to an Underlying Polymeric Substrate: Towards a Biohybrid Tissue Equivalent

This study investigates the feasibility of engineering a biohybrid cartilage equivalent (BCE) with the long-term goal of restoring the mechanical integrity and interfacial characteristics of severely damaged cartilage. The BCE depends on the successful adhesion, via mechanical interlocking, of a cartilage layer to a nondegradable composite scaffold or prosthesis. The model scaffold, consisting of a nonwoven mesh bonded to a solid core, was seeded with bovine articular chondrocytes. High molecular weight poly(L-lactic acid), which has a slow degradation time, was used to model the nondegradable polymer. Biochemical and histological analysis demonstrate that the BCE can support the growth of a cartilaginous matrix for at least 6 weeks in culture. Mechanical testing of the BCE showed cartilage adhesion strength increased from 19.27+/-1.62 to 43.79+/-3.88 kPa between 35 and 50 days in culture. Nonmechanically interlocked cartilage achieved less than 5% of this adhesion strength. For the first time, atomic force microscopy (AFM) was used to characterize surface topography of tissue-engineered cartilage. Surface roughness of constructs after 8 and 10 weeks ranged from 153 to 171 nm, falling within the range of native cartilage (100-600 nm). This study demonstrates the feasibility of creating a biohybrid cartilage equivalent by mechanically interlocking a cartilaginous layer to an underlying polymeric matrix.

Paclitaxel releasing films consisting of poly(vinyl alcohol)-graft-poly(lactide-co-glycolide) and their potential as biodegradable stent coatings

Although substantial progress in catheter and stent design has contributed to the success of percutaneous transluminal angioplasty (PTA) of atherosclerotic disease, the incidence of restenosis caused by in-stent neointimal hyperplasia remains a serious problem. Therefore, stents with a non-degradable polymer coating showing controlled release of active ingredients have become an attractive option for the site-specific delivery of anti-restenotic agents. Biodegradable coatings using polyesters, namely poly(lactic-co-glycolic acid) (PLGA) and different poly(vinyl alcohol)-graft-poly(lactic-co-glycolic acid) (PVA-g-PLGA) as paclitaxel-eluting stent coating materials were investigated here to evaluate their influence on the release kinetic. Whereas PLGA showed sigmoid release behavior, the paclitaxel release from PVA-g-PLGA films was continuous over 40 days without initial drug burst. Wide angle X-ray diffraction confirmed that paclitaxel is dissolved in the polymer matrix. Paclitaxel crystallization can be observed at a drug load of ≥ 10%. The effect of drug loading on polymer degradation was studied in films prepared from PVA 300-g-PLGA(30) with paclitaxel loadings of 5% and 15% over a time period of 6 weeks. The results suggest a surface-like erosion mechanism in films. A model stent (Jostent peripheral) coated with Parylene N, a poly(p-xylylene) (PPX) derivate, was covered with a second layer of PVA 300-g-PLGA(15), and PVA 300-g-PLGA(30) by using airbrush method. Morphology of coated stents, and film integrity after expansion from 3.12 to 5 mm was investigated by scanning electron microscopy (SEM). The devices resisted mechanical stress during stent expansion and merit further investigation under in vivo conditions.

Enzymatic Degradation of Liposome-Grafted Poly(hydroxyethyl l-glutamine)

Liposomes coated with poly(hydroxyethyl L-glutamine) (PHEG) show prolonged circulation times and biodistribution patterns comparable to PEG-coated liposomes. While PEG is a nondegradable polymer, PHEG is expected to be hydrolyzed by proteases. In this study the enzymatic degradability of PHEG both in its free form and grafted onto liposomes was investigated, using the proteases papain, pronase E, and cathepsin B. Enzymatic action was monitored with a ninhydrin assay, which quantifies amine groups formed due to hydrolysis of amide bonds, and the degradation products were characterized by MALDI-ToF mass spectrometry. PHEG, both in its free form and when grafted onto liposomes, showed degradation into low molecular weight peptides by the enzymes. Thus, we present a polymer-coated long-circulating liposome with an enzymatically degradable coating polymer, avoiding the risk of cellular accumulation.

Dual Porosity Expanded Polytetrafluoroethylene for Soft-Tissue Augmentation

A variety of nondegradable polymers have been evaluated for use as soft-tissue augmentation devices. This study compared a novel dual porosity expanded polytetrafluoroethylene with current, clinically used devices. Studies were performed in a porcine model of soft-tissue healing with both histologic evaluations and determination of biomechanical strength of tissue incorporation. Five different samples of expanded polytetrafluoroethylene were used in this study. Control devices were clinically available soft-tissue augmentation devices manufactured by W. L. Gore and Associates (Newark, Del.). Atrium Medical Corporation (Hudson, NH) manufactured three test devices with modified porosities. A total of 12 animals were used with implant evaluations performed after 1, 3, 6, and 12 months. Significant differences in tissue incorporation were observed morphologically with the dual porosity material, including reduced inflammation and increased cellular and extracellular matrix incorporation of the material. Significant increases in both angiogenesis (new vessel formation in the peri-implant tissue) and neovascularization (blood vessel penetration into the interstices of the implants) were observed with the dual porosity expanded polytetrafluoroethylene material. This novel dual porosity expanded polytetrafluoroethylene is associated with reduced inflammation and more extensive tissue incorporation as compared with the currently available form. These results suggest a dual porosity expanded polytetrafluoroethylene may provide a superior material for soft-tissue augmentation.

An NLS peptide covalently linked to linear DNA does not enhance transfection efficiency of cationic polymer based gene delivery systems

Transfection with non-viral gene delivery vectors, such as cationic polymers, generally results in low transgene expression in vivo. This is likely due to poor cytoplasmic transport and intra-nuclear DNA delivery. In this study two strategies to improve nuclear import were investigated. Linear DNA constructs with or without an NLS peptide were prepared by PCR. Alternatively, linear DNA obtained by enzymatic cleavage followed by capping of both ends with DNA-hairpins was used. An NLS peptide was attached to one of the capped ends of the linear DNA. Both biodegradable (pDMAEAppz) and non-degradable polymers (PEI or pDMAEMA) were used to complex the DNA. Several cell types, dividing and non-dividing, were transfected with the linear DNA constructs containing a SV40-derived NLS peptide. Nuclear import of the DNA constructs was studied using digitonin-permeabilized cells. Linear DNA prepared by PCR proved not useful as it was degraded from the 3'end. Linear DNA capped with hairpins was more successful with regard to stability. However, Cells transfected with linear DNA constructs by electroporation or by using cationic polymers with linear DNA containing a NLS peptide, failed to show significantly higher luciferase expression levels when compared to cells transfected with plasmid DNA or linear DNA without an NLS peptide attached. No nuclear localization was observed in digitonin-permeabilized cells. Taken together, these data demonstrate that this nuclear localisation signal when attached to DNA is neither able to improve transfection efficiency of cationic polymers nor the nuclear import of the DNA constructs.

Synergistic effect of combining UV-sunlight–soil burial treatment on the biodegradation rate of LDPE/starch blends

The present work has focused on the possibility of accelerating the biodegradation process of low-density polyethylene (LDPE) by mixing it with starch and exposing the obtained blend to the effect of UV radiation and/or soil burial treatments. Comparable studies between the properties of untreated LDPE/starch blends and those exposed to UV irradiation and soil burial treatment were investigated. In reference to the mechanical properties of untreated blends. The tensile strength of the blends exposed to UV irradiation-soil burial treatments was reduced by 20–66%, meanwhile, the tensile strength of the blends exposed only to soil burial treatment reduced by 10–26% from the initial value according to the starch content in the blend. The changes in the thermal, structural, and morphological properties of the blends due to the photo-irradiation and/or microbial treatments were determined using differential scanning calorimetry (DSC), transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The obtained results showed that there is a synergistic effect on the LDPE/starch biodegradation process when the blends exposed to UV-sunlight and followed by soil buried treatment. This means that photo-radiation induced oxidation reaction enhanced and accelerated the biodegradability rate of LDPE/starch blends by creating oxidized LDPE/starch that is more susceptible to biotic reactions. The results suggested that it is possible to replace non-degradable polyethylene polymer by biodegradable one for controlling the lifetime of its waste.

Pain Control Via Opioid Analgesic- Local Anesthetic Loaded IPNs

Relief of chronic pain is an important clinical problem requiring special care and approaches. The present study was designed for the construction of a controlled release system for local application of analgesics (hydromorphone (HM), morphine (M), and codeine (C)) and a local anesthetic, bupivacaine (BP). An interpenetrating network (IPN) drug release system was prepared by using a biocompatible, biodegradable copolyester, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and another biocompatible but synthetic, nondegradable polymer, poly (2- hydroxyethyl methacrylate), (PHEMA). In situ release kinetics of the IPN system was first order for BP but could not be fitted to any known equation for the other drugs. Complete release from the IPNs occurred within a considerably short time (24 h for 80 % of the drugs) most probably due to the significant hydrophilicity of PHEMA. In order to slow down the release rate these IPNs were coated with PHBV. Release from these coated IPNs (cIPN) resulted in rates that could be described by Higuchi's equations. In vivo measurement of antinociceptive efficacy was carried out in rats with tail flick and paw-withdrawal tests after inducing chronic pain created by sciatic nerve ligation at the right side. Control groups received placebo implants. In vivo studies showed potent, prolonged (2-3 days) antinociception at the site of injury (right paw) for strong opioids (HM and M) and about 2 days for the weak opioid (C) and local anesthetic (BP). In all cases the release rate was found to be as important as the antinociceptive potency. The weakest opioid analgesic of those evaluated (C) had a higher first day antinociception than its stronger counterpart M, probably due to its higher initial concentration that was expected from its faster release rate in the in situ experiments.

Mechanical Properties of Biomimetic Composites for Bone Tissue Engineering

ABSTRACTA biomimetic process involving in situ mineralization of hydroxyapatite (HAP) is used to design new composite biomaterials for bone tissue engineering. Surface and bulk properties of HAP composites have been studied for hydroxyapatite mineralized in absence (ex situ) of polyacrylic acid (PAAc) and in presence (in situ) of PAAc. XRD studies show existence of structural disorder within in situ HAP. It has been observed that PAAc increases the rate of crystallization. FTIR studies indicate calcium deficiency in structure of both in situ and ex situ HAP. PAAc provides favorable sites for nucleation of HAP. During crystallization of HAP, PAAc dissociates to form carboxylate ion, which binds to HAP. Porous and solid composites of in situ and ex situ HAP with polycaprolactone (PCL) in 50:50 ratio have been made to evaluate their applicability as bone scaffold. Mechanical tests on solid samples indicate ex situ HAP/PCL composites have higher elastic modulus (1.16 GPa) than in situ HAP/PCL composites (0.82 GPa). However, in case of porous composites, in situ HAP/PCL composites are found to have higher elastic modulus (29.5 MPa) than ex situ HAP/PCL composites (10.4 MPa). Nanoindentation tests were also performed at different loads to evaluate mechanical properties of the composites. In situ HAP mineralized using non-degradable polymers has thus been shown to improve mechanical response in porous composites.

CNS gene transfer mediated by a novel controlled release system based on DNA complexes of degradable polycation PPE-EA: a comparison with polyethylenimine/DNA complexes

Nonviral gene delivery systems based upon polycation/plasmid DNA complexes are quickly gaining recognition as an alternative to viral gene vectors for their potential in avoiding immunogenicity and toxicity problems inherent in viral systems. We investigated in this study the feasibility of using a controlled release system based on DNA complexed with a recently developed polymeric gene carrier, polyaminoethyl propylene phosphate (PPE-EA), to achieve gene transfer in the brain. A unique feature of this gene delivery system is the biodegradability of PPE-EA, which can provide a sustained release of DNA at different rates depending on the charge ratio of the polymer to DNA. PPE-EA/DNA complexes, naked DNA, and DNA complexed with polyethylenimine (PEI), a nondegradable cationic polymer known to be an effective gene carrier, were injected intracisternally into the mouse cerebrospinal fluid. Transgene expression mediated by naked DNA was mainly detected in the brain stem, a region close to the injection site. With either PPE-EA or PEI as a carrier, higher levels of gene expression could be detected in the cerebral cortex, basal ganglia, and diencephalons. Transgene expression in the brain mediated by PPE-EA/DNA complexes at an N/P ratio of 2 persisted for at least 4 weeks, with a significant higher level than that produced by either naked plasmid DNA or PEI/DNA at the 4-week time point. Furthermore, PPE-EA displayed much lower toxicity in cultured neural cells as compared to PEI and did not cause detectable pathological changes in the central nervous system (CNS). The results established the potential of PPE-EA as a new and biocompatible gene carrier to achieve sustained gene expression in the CNS.

Effect of Chain Extenders on Polyurethanes Containing Both Poly(butylene succinate) and Poly(ethylene glycol) as Soft Segments

Biodegradable polyure-thanes may be able to replace nondegradable polymers suchas polyethylene and polypropylene in fabrication ofpackaging films in near future as long as their mechanicalproperties are comparable to those of the common film-forming materials. Polyurethanes containing poly(ethylene glycol) (PEG) areinteresting since the hydrophilic PEG segments can enhancethe degradation. Furthermore, PEG itself has been frequentlyused as comonomers in preparing biodegradable polymersdue to its good biocompatibility and biodegradability.

Retardation of enzymatic degradation of microbial polyesters using surface chemistry: effect of addition of non-degradable polymers

The effects of addition of non-degradable polymers on the rate of enzymatic erosion for the poly(3-hydroxybutyrate- co-3-hydroxyvalerate) [P(3HB- co-3HV)] have been studied at 37 °C and pH 7.4 in the aqueous solution of an extracellular PHB depolymerase from Alcaligenes facalis. Polystyrene (PS) or poly(methyl methacrylate) (PMMA) was selected as a minor component (5 wt%) in a blend because of their non-enzymatic activity. Enzymatic degradation behaviors of the “as-cast” and “annealed” blend films were investigated using atomic force microscopy and weight loss measurements. Although the spherulites of P(3HB- co-3HV) cover all blend film surfaces throughout, the retardation of biodegradation in the P(3HB- co-3HV)/PS blend films was detected from morphological observation and weight loss measurement for both as-cast and annealed blend films while there was little difference between the P(3HB- co-3HV)/PMMA blend and pure P(3HB- co-3HV). Since the enzymatic degradation of P(3HB- co-3HV) initially occurs by a surface erosion process, these degradation behaviors were explained by the surface structure of blend films measured by X-ray photoelectron spectroscopy. The surface of P(3HB- co-3HV)/PS blend films revealed an excess of PS, whereas the surface of P(3HB- co-3HV)/PMMA blend films was nearly covered by P(3HB- co-3HV). It was concluded, therefore, that the PS, which exists within P(3HB- co-3HV) spherulites at surface acts as a retardant of enzymatic attack to the surface of the blend film.

표면 개질을 통한 미생물합성 폴리에스테르의 효소분해속도 조절

Since the enzymatic degradation of microbial poly[(R)-3-hydroxybutyrate-co-3-hydroxyvalerate] (P(3HB-co-3HV)) initially occurs by a surface erosion process, a degradation behavior could be controlled by the change of surface property. In order to control the rate of enzymatic degradation, plasma gas discharge and blending techniques were used to modify the surface of microbial P(3HB-co-3HV). The surface hydrophobic property of P(3HB-co-3HV) film was introduced by CF<TEX>$_3$</TEX>H plasma exposure. Also, the addition of small amount of polystyrene as a non-degradable polymer with lower surface energy to P(3HB-co-3HV) has been studied. The enzymatic degradation was carried out at 37 <TEX>$^{\circ}C$</TEX> in 0.1 M potassium phosphate buffer (pH 7.4) in the presence of an extracellular PHB depolymerase purified from Alcaligenes facalis T1. Both results showed the significant retardation of enzymatic erosion due to the hydrophobicity and the enzyme inactivity of the fluorinated- and PS-enriched surface layers.