PHB Membranes Research Articles

Poly-3-hydroxybutyrate-silver nanoparticles membranes as advanced antibiofilm strategies for combatting peri-implantitis

Dental implant success is threatened by peri-implantitis, an inflammation leading to implant failure. Conventional treatments struggle with the intricate microbial and host factors involved. Antibacterial membranes, acting as barriers and delivering antimicrobials, may offer a promising solution. Thus, this study highlights the potential of developing antibacterial membranes of poly-3-hydroxybutyrate and silver nanoparticles (Ag Nps) to address peri-implantitis challenges, discussing design and efficacy against potential pathogens.Electrospun membranes composed of PHB microfibers and Ag Nps were synthesized in a blend of DMF/chloroform at three different concentrations. Various studies were conducted on the characterization and antimicrobial activity of the membranes. The synthesized Ag Nps ranged from 4 to 8 nm in size. Furthermore, Young's modulus decreased, reducing from 13.308 MPa in PHB membranes without Ag Nps to 0.983 MPa in PHB membranes containing higher concentrations of Ag Nps. This demonstrates that adding Ag Nps results in a less stiff membrane. An increase in elongation at break was noted with the rise in Ag Nps concentration, from 23.597 % in PHB membranes to 60.136 % in PHB membranes loaded with Ag Nps.The antibiotic and antibiofilm activity of the membranes were evaluated against Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus mutans, and Candida albicans. The results indicated that all PHB membranes containing Ag Nps exhibited potent antibacterial activity by inhibiting the growth of biofilms and planktonic bacteria. However, inhibition of C. albicans occurred only with the PHB-Ag Nps C membrane.These findings emphasize the versatility and potential of Ag Nps-incorporated membranes as a multifunctional approach for preventing and addressing microbial infections associated with peri-implantitis. The combination of antibacterial and antibiofilm properties in these membranes holds promise for improving the management and treatment of peri-implantitis-related complications.

Validation of kinetic modeling of progesterone release from polymeric membranes

Mathematical modeling in drug release systems is fundamental in development and optimization of these systems, since it allows to predict drug release rates and to elucidate the physical transport mechanisms involved. In this paper we validate a novel mathematical model that describes progesterone (Prg) controlled release from poly-3-hydroxybutyric acid (PHB) membranes. A statistical analysis was conducted to compare the fitting of our model with six different models and the Akaike information criterion (AIC) was used to find the equation with best-fit. A simple relation between mass and drug released rate was found, which allows predicting the effect of Prg loads on the release behavior. Our proposed model was the one with minimum AIC value, and therefore it was the one that statistically fitted better the experimental data obtained for all the Prg loads tested. Furthermore, the initial release rate was calculated and therefore, the interface mass transfer coefficient estimated and the equilibrium distribution constant of Prg between the PHB and the release medium was also determined. The results lead us to conclude that our proposed model is the one which best fits the experimental data and can be successfully used to describe Prg drug release in PHB membranes.

Surface functionalized electrospun fibrous poly(3-hydroxybutyrate) membranes and sleeves: a novel approach for fixation in anterior cruciate ligament reconstruction.

Effective osteointegration for fixation of the tendon to bone junction is the most important issue in anterior cruciate ligament (ACL) reconstruction. In this study, functionalized electrospun poly(3-hydroxybutyrate) (PHB) membranes and sleeves were prepared and evaluated for the fixation of the tendon to bone junction. The electrospun fibrous PHB membranes were modified with hydrogen peroxide, dopamine (DA), chitosan (CS), glutaraldehyde (GA), and then immobilized with growth factors (GFs) from platelet rich plasma (PRP). The water-contact angle measurement showed enhanced wettability in the membranes after the sequential surface functionalization. Successful graftings of DA, CS and GFs from PRP on the membrane surface were demonstrated using X-ray photoelectron spectroscopy (XPS). The ninhydrin assay revealed the amount of immobilized TGF-β1 and PDFG-AB. The modified membranes showed good biocompatibility in an in vitro rabbit tenocyte cultivation study, as the cells showed good attachment and proliferation activity. Significant increases in extracellular matrix and gene expression of type I collagen were observed when the membrane surface was treated with the GFs from PRP. In a rabbit model, the tendon to bone junction was filled with newly formed fibrocartilage and osteointegration behavior was observed. This suggests that the use of functionalized PHB sleeves can enhance tendon to bone healing and the tendon sleeves might provide a novel method for ACL reconstruction.

Acrylic acid plasma polymerized poly(3-hydroxybutyrate) membranes for methanol/MTBE separation by pervaporation

Plasma polymerized acrylic acid (AA) thin films on poly(3-hydroxybutyrate) (PHB) membranes were evaluated as composite membranes for methanol/methyl tert-butyl ether (MTBE) separation by pervaporation (PV). Composite membranes were prepared in an inductively coupled radiofrequency plasma reactor. Experiments were performed at different powers (7.2 to 29.2W) and pressures, using pure AA monomer, as well as AA/air and AA/argon mixtures. Depositions chemical characteristics were determined through FTIR spectroscopy, hydrophilic character through contact angle measurements, and SEM images were also taken to analyze surface morphology. In PV measurements, membranes were methanol selective; the separation factor exceeded that of pure PHB membranes in all cases. Fluxes were lower than the original membrane but the performance separation index (PSI) was always higher. Results presented in terms of permeability were between 660 and 4045barrer for methanol, while for MTBE they were markedly lower, between 10.5 and 57.7barrer. These large differences in permeabilities caused high selectivities which ranged from 24 to 79.

Antibacterial Nanostructured Polyhydroxybutyrate Membranes for Guided Bone Regeneration.

The principle of guided bone regeneration (GBR) in orthopedic, cranio-maxillofacial and dental tissue engineering applications is to create a secluded space for the treatment of large bone defects while excluding fibrous connective tissue formation at the defect area. In dental surgeries, a GBR membrane is placed near the dental implant in post-extraction sockets to grow new bone at the implant site, along with inhibiting infection due to the microbial nature of the mouth flora. Poly[(R)-3-hydroxybutyric acid] (PHB) is a natural polyester synthesized by a wide variety of microorganisms which has been proposed for various biomedical applications. In this study, to improve the performance of PHB as a GBR, a NaOH based alkaline treatment was designed to create nanofeatured PHB membranes. The newly fabricated nanofeatured PHB membranes were investigated for GBR applications. The results showed that a quick, simple, and inexpensive sodium hydroxide treatment modified the nanostructured surface morphology and chemistry of the PHB membranes by inducing hydrolysis of the ester bonds in the PHB backbone creating carboxylic surface functional groups, which increased the hydrophilicity of the PHB surfaces. Cytocompatibility studies showed increased proliferation of human osteoblasts (bone forming cells) on the NaOH treated PHB membranes compared to the untreated ones. Importantly, in vitro bacterial studies with Staphylococcus aureus (S. aureus) indicated that the NaOH-treated PHB surfaces inhibited S. aureus growth more than 60% after 48 hours of culture compared to the untreated PHB membrane. Thus, this study, for the first time, showed that nanofeatured PHB membranes modified with a NaOH treatment may be a useful anti-bacterial, osteoconductive GBR membrane for numerous orthopedic, cranio-maxillofacial and dental tissue engineering applications.

Sorption and pervaporation of methanol/water mixtures with poly(3-hydroxybutyrate) membranes

In this contribution, poly(3-hydroxybutyrate) (PHB) membranes were evaluated in sorption and pervaporation experiments for methanol/water separation. Single component sorption tests showed that PHB membranes have higher affinity toward methanol than water: at 40°C the sorption degree was 18.4 and 1.1%, respectively. This was in agreement with contact angle measurements, performed with both liquids, and Hansen solubility parameter. PHB sorption degree in the whole methanol/water composition range and three temperature levels were determined, showing an anomalous behavior (sigmoid like curves). A simple technique, named by us “Desorption by Dissolution”, was developed to determine sorbed mixture composition. It basically consists on dissolving the polymer after sorption equilibrium in the mixture has been reached, to completely extract the mixture. Then, chromatographic analysis is used to determine solution composition. It does not require adapting equipment or using vacuum devices neither cold traps. When both components were present, methanol grams sorbed in the membrane were always lower than the mixture in which they were immersed, while water sorption was enhanced due to methanol presence. Very low standard deviation values were registered (<0.84) confirming the technique reliability. Single component fluxes and mass flux ratio in pervaporation increased with temperature: methanol flux was 3.5×10−5kgm−2s−1 at 25°C, whereas at 50°C exceeded 7×10−5kgm−2s−1; water flux increased from 1.8×10−5kgm−2s−1 at 30°C to 2.2×10−5kgm−2s−1 at 50°C. Since permeances decreased, the increase in fluxes with temperature can be attributed to the increase in vapor pressure driving forces. Mixture pervaporation results showed similar behavior, highlighting the fact that separation factor increased with temperature as well: 3.5 at 30°C and 3.8 at 50°C. Selectivities were higher than 12 for 10wt% water/methanol+water mixtures. Results were discussed in terms of polymer crystallinity, solubility parameters, component size, activation energies and cluster formation.

Sorption and pervaporation with poly(3-hydroxybutyrate) membranes: methanol/methyl tert-butyl ether mixtures

Sorption and pervaporation experiments to study the methanol/methyl tert-butyl ether (MTBE) separation, were carried out with poly(3-hydroxybutyrate) (PHB) membranes. Single component tests showed that PHB membranes were methanol selective and pervaporation fluxes increased with temperature, as expected. However, permeability coefficients showed quite different behavior for each component. Mixture pervaporation results showed an increase in flux and separation factor with temperature, and a significant enhancing of flux due to MTBE. Sorption mixture behavior exhibited a maximum as feed methanol concentration increased. The same tendency was reflected in pervaporation permeability coefficients with the maximum value occurring near azeotropic concentration. The results were discussed in terms of physico-chemical properties of the system, as polymer crystallinity and thermal transitions, solubility parameters, component kinetic diameters, plasticization and coupling effects. Very high fluxes and selectivities up to 9 indicate promising prospects for the PHB membranes.

Formation of microporous poly(hydroxybutyric acid) membranes for culture of osteoblast and fibroblast

AbstractMicroporous membranes of a biodegradable polymer, poly(hydroxybutyric acid) (PHB), were prepared by a phase‐inversion process and their cell compatibility was evaluated in vitro. A ternary system, ethanol/chloroform/PHB, was employed to prepare the membranes, wherein ethanol and chloroform were served as the nonsolvent and solvent for PHB, respectively. In the phase‐inversion process, the polymer dissolution temperature was varied from 80 to 120°C to yield membranes with specific morphologies, such as globular particles, porous channels, etc. Moreover, cell viability was examined on the formed membranes. Two cell lines, osteoblast hFOB1.19 and fibroblast L929, were cultured in vitro. It was found that these two types of cells exhibited different responses on different membranes: the hFOB1.19 cells showed significant increase in cell proliferation with increase in surface roughness, whereas the L929 cells demonstrated an opposite trend, preferring to attach and grow on a flat surface. PHB membranes with different morphologies exhibit different cell compatibilities, which may be useful means for the architectural design of materials for tissue engineering. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Controlled release of antiseptic drug from poly(3-hydroxybutyrate)-based membranes. combination of diffusion and kinetic mechanisms

A polymeric system based on biocompatible and biodegradable poly(3-hydroxybutyrate) (PHB) is proposed for controlled release of furacilin (Frc). The kinetics of Frc release from PHB membranes containing 0.5–5.0 wt% Frc into a model aqueous medium at 25°C have been studied using a UV spectroscopy technique. The drug release profiles present a combination of diffusion and kinetic components. The diffusion component of the release kinetics has been analyzed and the dependence of the diffusivity on the drug concentrations has been determined. The rate constant of the release kinetics depends on the Frc concentration and is related to the hydrolytic destruction of PHB. The PHB hydrolysis is most clearly demonstrated in long-term experiments (after the first week of drug release). The obtained results are useful for the development of new controlled drug delivery systems containing several drugs, which provide a combined action on tissues and organs of the organism.

Water and vapor permeability at different temperatures of poly (3-Hydroxybutyrate) dense membranes

Polyhydroxyalkanoates (PHAs) are polymers produced from renewable resources with biodegradability and biocompatibility, being therefore attractive for medical and pharmaceutical purposes. Poly (3-hydroxybutyrate) (PHB) is the most important polymer of this family by considering the biotechnology process of its synthesis. In the present study, dense films of PHB were prepared by casting from chloroform solutions (1% m/m). Permeability studies with water, methanol, ethanol and n-propanol were performed using the gravimetric method at different temperatures (from 50 ºC to 65 ºC). Results provide new data on permeability coefficients of PHB membranes.

Transport water and molecular mobility in novel barrier membranes with different morphology features

Bacterial poly(3-hydroxybutyrate) (PHB) — a new biopolymer and its derivatives are being extensively applied in medicine, biotechnology and membrane technologies. The relationship between structure-transport parameters and molecular mobility of PHB was investigated by quartz McBain's microbalance, X-ray diffraction and ESR method. Two types of the PHB membranes with different structural organisation-isotropic and textured-were studied. The specific features of the sorption and diffusion characteristics of PHB are related to the structural organisation. The polymer matrixes are characterised by significantly microstructural heterogeneity as it was shown by the spin probe (TEMPO/TEMPOL) measurements. A non-crystalline phase of PHB includes two kinds of microfields with different molecular mobility. Moisture is found to change both the velocity of molecular motion and the mole content of such microfields. The diffusion behaviour of the membranes has been explained in accordance with dynamic information based on the ESR method.