Fabrication and Evaluation of Polycaprolactone–Poly(hydroxybutyrate) or Poly(3‐Hydroxybutyrate‐co‐3‐Hydroxyvalerate) Dual‐Leached Porous Scaffolds for Bone Tissue Engineering Applications

Polycaprolactone (PCL) blend with poly(hydroxybutyrate) (PHB) or poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) dual‐leached scaffolds are prepared by using the solvent casting and salt–polymer‐leaching technique. The blending of the PHB and PHBV in PCL scaffolds results in decreased porosities of the scaffolds, and the water absorption capacities of the scaffolds also decrease. The compressive modulus of the PCL–PHB and PCL–PHBV dual‐leached scaffolds is greatly increased by the blending of PHB or PHBV matrix. An indirect cytotoxicity evaluation of all scaffolds with mouse fibroblastic cells (L929) and mouse calvaria‐derived preosteoblastic cell (MC3T3‐E1) indicates that all dual‐leached scaffolds are posed as nontoxic to cells. Both PCL–PHB and PCL–PHBV dual‐leached scaffolds are supported by the attachment of MC3T3‐E1 at significantly higher levels to tissue culture polystyrene plate (TCPS) and are able to support the proliferation of MC3T3‐E1 at higher levels to that cells on TCPS and PCL scaffolds. For mineralization, cells cultured on surfaces of PCL–PHB and PCL–PHBV dual‐leached scaffolds show higher mineral deposition than on TCPS and PCL scaffold.

     

Fabrication of nano/microfiber scaffolds using a combination of rapid prototyping and electrospinning systems

Tissue‐engineered scaffolds require an adequate three‐dimensional (3‐D) structure for cell growth and attachment. Solid freeform fabrication can provide the interconnected pore to induce the cell ingrowth, and electrospinning technique can make the nanofiber web with high surface for cell attachment. In this study, 3‐D polycaprolactone (PCL) scaffolds were fabricated using a rapid prototyping plotting system coupled with an electrospinning apparatus. Scanning electron micrographs showed that these hybrid scaffolds had a regular microfiber structure with interconnected pores and a nanofiber distribution appropriate for cell attachment. Scaffolds were seeded with MG63 cells for in vitro study and implanted in the tibia of rabbit for in vivo study. The resulting structure also facilitated cell adhesion, proliferation, and differentiation as evidenced by biochemical analyses and confocal microscopy. The hybrid scaffolds also exhibited good biocompatibility and osteoconductivity in animal studies. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Biocomposite scaffolds for 3D cell culture: Propolis enriched polyvinyl alcohol nanofibers favoring cell adhesion

The objective of this work is generation of propolis/polyvinyl alcohol (PVA) scaffold by electrospinning for 3D cell culture. Here, PVA used as co-spinning agent since propolis alone cannot be easily processed by electrospinning methodology. Propolis takes charge in maximizing biological aspect of scaffold to facilitate cell attachment and proliferation. Morphological analysis showed size of the electrospun nanofibers varied between 172–523 nm and 345–687 nm in diameter, for non-crosslinked and crosslinked scaffolds, respectively. Incorporation of propolis resulted in desired surface properties of hybrid matrix, where hybrid scaffolds highly favored protein adsorption. To examine cell compatibility, NIH-3T3 and HeLa cells were seeded on propolis/PVA hybrid scaffold. Results confirmed that integration of propolis supported cell adhesion and cell proliferation. Also, results indicated electrospun propolis/PVA hybrid scaffold provide suitable microenvironment for cell culturing. Therefore, developed hybrid scaffold could be considered as potential candidate for 3D cell culture and tissue engineering.     

Bone scaffolds from electrospun fiber mats of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and their blend

In the present contribution, electrospinning was used to fabricate ultrafine fiber mats from poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-2-hydroxyvalerate) (PHBV), and their 50/50 w/w blend for potential use as bone scaffolds. Cytotoxicity evaluation of these as-spun fiber mats with human osteoblasts (SaOS-2) and mouse fibroblasts (L929) indicated biocompatibility of these materials to both types of cells. The potential for use of these fiber mats as bone scaffolds was further assessed in vitro in terms of the attachment, the proliferation, and the alkaline phosphatase (ALP) activity of SaOS-2 that were seeded or cultured at different times. The cells appeared to adhere well on all types of the fibrous scaffolds after 16 h of cell seeding. During the early stage of the proliferation period (i.e., from ∼24 to 72 h in culture), the viability of the cells increased considerably and appeared to be unchanged with further increase in the time in culture. In comparison with the corresponding solution-cast film scaffolds, all of the fibrous scaffolds exhibited much better support for cell attachment and proliferation. Lastly, among the various fibrous scaffolds investigated, the electrospun fiber mat of the 50/50 w/w PHB/PHBV blend showed the highest ALP activity. These results implied a high potential for use of these electrospun fiber mats as bone scaffolds.     

Random and aligned PLLA : PRGF electrospun scaffolds for regenerative medicine

Random and aligned electrospun scaffolds were prepared combining poly(l ‐lactic acid) (PLLA) and activated platelet‐rich plasma (PRGF) at various proportions, with the aim of elucidating the role of nanofibers orientation and growth factors on cell attachment and proliferation. PRGF is released from scaffolds in a sustained way for at least 3 weeks, without an initial burst effect. Mesenchymal stem cells (MSCs) seeded on the random scaffolds present a polygonal and random orientation in any direction of the scaffold. On the other hand, aligned scaffolds are able to promote cell attachment and proliferation in the direction of the nanofibers. The incorporation of PRGF in the scaffolds enhances cell proliferation for at least 2 weeks. Overall, aligned electrospun PLLA : PRGF scaffolds can encapsulate growth factors at relatively large proportions and sustain their release to enhance cell attachment and proliferation as well as eliciting cell alignment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41372.     

Immobilization of polyvinyl alcohol-siloxane on the oxygen plasma-modified polyurethane-carbon nanotube composite matrix

Polyurethane-based scaffolds have been considered as a promising strategy for tissue regeneration. Herein, the polyurethane and carbon nanotubes electrospun scaffolds were modified by polyvinyl alcohol-3-glycidoxypropyl-trimethoxysilane after oxygen plasma treatment to improve physicochemical and in vitro properties for efficient bone reconstruction. Finally, the morphology of scaffolds, chemical characterization, surface roughness, bioactivity, hydrophilicity, cell attachment, cell viability, and alkaline phosphatase activity were investigated. According to microscopy results, bead free and smooth fibers were obtained using electrospinning while the degree of uniformity was reduced after the surface modification process. However, the modification process induced higher hydrophilicity and bioactivity to prepared scaffolds. In addition, the attachment and viability of the cells were improved as a function of surface modification. The expression of alkaline phosphatase especially in modified fibers confirmed the initial potential of scaffolds for bone tissue engineering applications and further studies. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48477.     

Three-dimensional coating of nanofibers on surfaces of poorly conductive objects

Rectangular-shaped, poorly conductive synthetic polymer scaffolds composed of a mixture of polycaprolactone and poly-L-lactic acid (PCL/PLLA, 75:25) were coated directly with nanofibers composed of PLLA using an electrospinning technique having a modified design for the electrically grounded collector. The design modification consisted of mounting each scaffold onto a fine-point needle which was attached directly to the ground electrode of the electrospinning unit. Nanofibers were collected on all six surfaces of each scaffold. The coated scaffolds were then dried at ambient temperature overnight before sterilization by immersion in 100% ethanol to assess and ensure adherence between the scaffold and nanofibers. Photomicrographs from scanning electron microscopy illustrate nanofiber coverage over all six surfaces of the polymer scaffold. The design in this manner for three-dimensional coating of poorly conductive objects advances electrospinning capability for numerous new applications.     

Surface Modification of Electrospun TPU Nanofiber Scaffold with CNF Particles by Ultrasound‐Assisted Technique for Tissue Engineering

A straightforward, fast, and versatile technique is developed to fabricate nanofibrous scaffold with excellent hydrophilicity, mechanical properties, and biocompatibility for tissue engineering. The thermoplastic polyurethane (TPU) nanofiber is fabricated by utilizing electrospinning, and then its surface is modified through simply immersing it into cellulose nanofibrils (CNF) dispersion and subjecting to ultrasonication. The results show that the CNF particles are successfully absorbed on the surface of TPU nanofiber. By introducing CNF particles on the surface of TPU nanofiber, the hydrophilicity, mechanical properties of fabricated CNF‐absorbed TPU scaffold are significantly increased. Additionally, the adhesion and proliferation of human umbilical vein endothelial cells cultured on CNF‐absorbed TPU scaffold are prominently enhanced in comparison with those of cultured on TPU scaffold. These findings suggest that the ultrasound‐assisted technique opens up a new way to simply and effectively modify the surface of various scaffolds and the modified scaffold could be shown a great potential in tissue engineering.     

Application of low loading of collagen in electrospun poly[(l‐lactide)‐co‐(ε‐caprolactone)] nanofibrous scaffolds to promote cellular biocompatibility

Electrospinning of various polymers has been used to produce nanofibrous scaffolds that mimic the extracellular matrix and support cell attachment for the potential repair and engineering of nerve tissue. In the study reported here, an electrospun copolymer of l ‐lactide and ε‐caprolactone (67:33 mol%) resulted in a nanofibrous scaffold with average fibre diameter and pore size of 476 ± 88 and 253 ± 17 nm, respectively. Blending with low loadings of collagen (<2.5% w/w) significantly reduced the average diameter and pore size. The uniformity of fibre diameter distributions was supported with increasing collagen loadings. The nanofibrous scaffolds significantly promoted the attachment and proliferation of olfactory ensheathing cells compared to cells exhibiting asynchronous growth. Furthermore, analysis of cell health through mitochondrial activity, membrane leakage, cell cycle progression and apoptotic indices showed that the nanofibrous membranes promoted cell vigour, reducing necrosis. The study suggests that the use of more cost‐effective, low loadings of collagen supports morphological changes in electrospun poly[(l ‐lactide)‐co‐(ε‐caprolactone)] nanofibrous scaffolds, which also support attachment and proliferation of olfactory ensheathing cells while promoting cell health. The results here support further investigation of the electrospinning of these polymer blends as conduits for nerve repair. © 2013 Society of Chemical Industry     

Development of fibrin conjugated chitosan/nano β‐TCP composite scaffolds with improved cell supportive property for bone tissue regeneration

In the present study, an attempt has been made to improve cell supportive property of chitosan/nano beta tri‐calcium phosphate (β‐TCP) composite scaffolds by modification of scaffold surface with fibrin using ethyl‐3‐(3‐dimethylaminopropyl) carbodimide (EDC) as crosslinking agent. The developed fibrin conjugated chitosan/nano β‐TCP composite scaffolds possess desired pore size and porosity in the range of 45–151 µm and 81.4 ± 4.1%, respectively. No significant change in compressive strength of scaffolds was observed before and after fibrin conjugation. The calculated compressive strength of fibrin conjugated and non‐conjugated chitosan/nano β‐TCP scaffolds are 2.71 ± 0.14 MPa and 2.67 ± 0.11 MPa, respectively. Results of cell culture study have further shown an enhanced cell attachment, cell number, proliferation, differentiation, and mineralization on fibrin conjugated chitosan/nano β‐TCP scaffold. The uniform cell distribution over the scaffold surface and cell infiltration into the scaffold pores were assessed by confocal laser scanning microscopy. Furthermore, higher expression of osteogenic specific genes such as bone sialo protein, osteonectin, alkaline phosphatase, and osteocalcin (OC) on fibrin conjugated scaffolds was observed when compared to scaffolds without fibrin. Altogether, results indicate the potentiality of developed fibrin conjugated composite scaffolds for bone tissue engineering applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41534.     

Functionally modified,melt‐electrospun thermoplastic polyurethane mats for wound‐dressing applications

The electrospinning of a polymer melt is an interesting process for medical applications because it eliminates the cytotoxic effects of solvents in the electrospinning solution. Wound dressings made from thermoplastic polyurethane (TPU), particularly as a porous structured electrospun membrane, are currently the focus of scientific and commercial interest. In this study, we developed a functionalized fibrillar structure as a novel antibacterial wound‐dressing material with the melt‐electrospinning of TPU. The surface of the fibers was modified with poly(ethylene glycol) (PEG) and silver nanoparticles (nAg's) to improve their wettability and antimicrobial properties. TPU was processed into a porous, fibrous network of beadless fibers in the micrometer range (4.89 ± 0.94 μm). The X‐ray photoelectron spectroscopy results and scanning electron microscopy images confirmed the successful incorporation of nAg's onto the surface of the fiber structure. An antibacterial test indicated that the PEG‐modified nAg‐loaded TPU melt‐electrospun structure had excellent antibacterial effects against both a Gram‐positive Staphylococcus aureus strain and Gram‐negative Escherichia coli compared to unmodified and PEG‐modified TPU fiber mats. Moreover, modification with nAg's and PEG increased the water‐absorption ability in comparison to unmodified TPU. The cell viability and proliferation on the unmodified and modified TPU fiber mats were investigated with a mouse fibroblast cell line (L929). The results demonstrate that the PEG‐modified nAg‐loaded TPU mats had no cytotoxic effect on the fibroblast cells. Therefore, the melt‐electrospun TPU fiber mats modified with PEG and nAg have the potential to be used as antibacterial, humidity‐managing wound dressings. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40132.     

Nanofibrous scaffold prepared by electrospinning of poly(vinyl alcohol)/gelatin aqueous solutions

A series of nanofibrous scaffolds were prepared by electrospinning of poly(vinyl alcohol) (PVA)/gelatin aqueous solution. PVA and gelatin was dissolved in pure water and blended in full range, then being electrospun to prepared nanofibers, followed by being crosslinked with glutaraldehyde vapor and heat treatment to form nanofibrous scaffold. Field emission scanning electron microscope (FESEM) images of the nanofibers manifested that the fiber average diameters decreased from 290 to 90 nm with the increasing of gelatin. In vitro degradation rates of the nanofibers were also correlated with the composition and physical properties of electrospinning solutions. Cytocompatibility of the scaffolds was evaluated by cells morphology and MTT assay. The FESEM images revealed that NIH 3T3 fibroblasts spread and elongated actively on the scaffolds with spindle‐like and star‐type shape. The results of cell attachment and proliferation on the nanofibrous scaffolds suggested that the cytotoxicity of all samples are grade 1 or grade 0, indicating that the material had sound biosafety as biomaterials. Compared with pure PVA and gelatin scaffolds, the hybrid ones possess improved biocompatibility and controllability. These results indicate that the PVA/gelatin nanofibrous have potential as skin scaffolds or wound dressing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Bone morphogenetic protein‐2 immobilization on porous PCL‐BCP‐Col composite scaffolds for bone tissue engineering

The objective of this study was to develop novel porous composite scaffolds for bone tissue engineering through surface modification of polycaprolactone–biphasic calcium phosphate‐based composites (PCL–BCP). PCL–BCP composites were first fabricated with salt‐leaching method followed by aminolysis. Layer by layer (LBL) technique was then used to immobilize collagen (Col) and bone morphogenetic protein (BMP‐2) on PCL–BCP scaffolds to develop PCL–BCP–Col–BMP‐2 composite scaffold. The morphology of the composite was examined by scanning electron microscopy (SEM). The efficiency of grafting of Col and BMP‐2 on composite scaffold was measured by X‐ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Both XPS and FTIR confirmed that Col and BMP‐2 were successfully immobilized into PCL–BCP composites. MC3TC3‐E1 preosteoblasts cells were cultivated on composites to determine the effect of Col and BMP‐2 immobilization on cell viability and proliferation. PCL–BCP–Col–BMP‐2 showed more cell attachment, cell viability, and proliferation bone factors compared to PCL–BCP‐Col composites. In addition, in vivo bone formation study using rat models showed that PCL–BCP–Col–BMP‐2 composites had better bone formation than PCL–BCP‐Col scaffold in critical size defect with 4 weeks of duration. These results suggest that PCL–BCP–Col–BMP‐2 composites can enhance bone regeneration in critical size defect in a rat model with 4 weeks of duration. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45186.     

Poly(ethylene glycol)‐modulated cellular biocompatibility of polyhydroxyalkanoate films

Polyhydroxybutyrate (PHB) and its copolymer with hydroxyvalerate, P(HB‐co‐HV), are widely used biomaterials. In this study, improvements of their biological properties of degradability and compatibility were achieved by blending with low‐molecular‐weight poly(ethylene glycol) (PEG106) approved for medical use. Surface morphology and chemistry are known to support cell attachment. Attachment and proliferation of neural olfactory ensheathing cells increased by 17.0 and 32.2% for PHB and P(HB‐co‐HV) composite films. Cell attachment was facilitated by increases in surface hydrophilicity, water contact angles decreased by 26 ± 2° and water uptake increased by 23.3% depending upon biopolymer and PEG loading. Cells maintained high viability (>95%) on the composite films with no evidence of cytotoxic effects. Assays of mitochondrial function and cell leakage showed improved cell health as a consequence of PEG loading. The PEG component was readily solubilised from composite films, allowing control of degradation profiles in the cell growth medium. Promotion of biopolymer compatibility and degradability was not at the expense of material properties, with the extension to break of the composites increasing by 5.83 ± 1.06%. Similarly, crystallinity decreased by 36%. The results show that blending of common polyhydroxyalkanoate biomaterials with low‐molecular‐weight PEG can be used to promote biocompatibility and manipulate physiochemical and material properties as well as degradation.© 2013 Society of Chemical Industry     

Generation of antifouling layers on stainless steel surfaces by plasma‐enhanced crosslinking of polyethylene glycol

Polyethylene glycol (PEG) structures were deposited onto stainless steel (SS) surfaces by spin coating and argon radio frequency (RF)‐plasma mediated crosslinking. Electron spectroscopy for chemical analysis (ESCA) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR) indicated the presence of  CH₂ CH₂ O structure and C C C linkage, as a result of the plasma crosslinking, on PEG‐modified SS surfaces. Scanning electron microscopy (SEM) indicated complete deposition, and water contact angle analysis revealed higher hydrophilicity on PEG‐modified surfaces compared to unmodified SS surfaces. Surface morphology and roughness analysis by atomic force microscopy (AFM) revealed smoother SS surfaces after PEG modification. The evaluation of antifouling ability of the PEG‐modified SS surfaces was carried out. Compared to the unmodified SS, PEG‐modified surfaces showed about 81–96% decrease in Listeria monocytogenes attachment and biofilm formation (p < 0.05). This cold plasma mediated PEG crosslinking provided a promising technique to reduce bacterial contamination on surfaces encountered in food‐processing environments. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 485–497, 2005     

Fabrication and characterization of electrospun fibrous nanocomposite scaffolds based on poly(lactide‐co‐glycolide)/poly(vinyl alcohol) blends

Tissue engineering involves the fabrication of three‐dimensional scaffolds to support cellular in‐growth and proliferation. Ideally, the scaffolds should be similar to the native extracellular matrix (ECM). Electrospun polymer nanofibrous scaffolds are appropriate candidates for ECM mimetic materials since they mimic the nanoscale properties of ECM. Electrospun polymer nanocomposites based on poly(lactide‐co‐glycolide) (PLGA)/poly(vinyl alcohol) (PVA) and organically modified montmorillonite (OMMT) were prepared by a solution intercalation technique followed by electrospinning. The morphology of fibrous scaffolds based on these nanocomposites was investigated using scanning electron microscopy. The scaffolds showed highly porous structure within the nanofibres of diameters ranging from 400 to 700 nm. X‐ray diffractometry gave evidence of good dispersion of the OMMT in the blends with exfoliated morphology. Measurements of the water uptake and water contact angle of the fibrous scaffolds indicated significant improvement in the hydrophilicity of the scaffolds. Evaluations of the mechanical properties and unrestricted somatic stem cell culture of the electrospun fibrous nanocomposite scaffolds revealed that the PLGA90/PVA10/1.5% OMMT and PLGA90/PVA10/3% OMMT samples are the most useful from the tissue engineering application viewpoint. Copyright © 2010 Society of Chemical Industry     

Fabrication of PLA/PEG/MWCNT electrospun nanofibrous scaffolds for anticancer drug delivery

In the present study, polylactic acid (PLA)/polyethylene glycol (PEG)/multiwalled carbon nanotube (MWCNT) electrospun nanofibrous scaffolds were prepared via electrospinning process and their applications for the anticancer drug delivery system were investigated. A response surface methodology based on Box–Behnken design (BBD) was used to evaluate the effect of key parameters of electrospinning process including solution concentration, feeding rate, tip–collector distance (TCD) and applied voltage on the morphology of PLA/PEG/MWCNT nanofibrous scaffolds. In optimum conditions (concentration of 8.15%, feeding rate of 0.2 mL/h, voltage of 18.50 kV and TCD of 13.0 cm), the minimum experimental fiber diameter was found to be 225 nm which was in good agreement with the predicted value by the BBD analysis (228 nm). In vitro drug release study of doxorubicin (DOX)‐loaded nanofibrous scaffolds, higher drug content induced an extended release of drug. Also, drug release rate was not dependent on drug/polymer ratio in different electrospun nanofibrous formulations. The equation of M_t = c₀ + kt^0.5was used to describe the kinetic data of DOX release from electrospun nanofibers. The cell viability of DOX‐loaded nanofibrous scaffolds was evaluated using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide, a tetrazole assay on lung cancer A549 cell lines. We propose that DOX‐incorporated PLA/PEG/MWCNT nanofibrous scaffold could be used as a superior candidate for antitumor drug delivery. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41286.     

Ultrasonication‐Induced Modification of Hydroxyapatite Nanoparticles onto a 3D Porous Poly(lactic acid) Scaffold with Improved Mechanical Properties and Biocompatibility

A 3D porous poly(lactic acid) (PLA) scaffold with high porosity and well‐connected pores is fabricated using a vacuum‐assisted solvent casting technique. Its surface is modified with hydroxyapatite (HA) nanoparticles using ultrasonication to prepare an HA‐modified PLA/HA scaffold. For reference, an HA‐blended (b‐PLA‐HA) scaffold is fabricated via the solution blending method. The morphology, porosity, hydrophilicity, swelling ratio, mechanical properties, and cell viability of the PLA, b‐PLA‐HA, and PLA/HA scaffolds are systematically studied. The results show that HA nanoparticles are successfully introduced onto the surface of the PLA/HA scaffold, and strong interactions occur between the HA nanoparticles and the PLA matrix. The PLA/HA scaffold still has a high porosity of more than 85% after ultrasonication. The hydrophilicity and mechanical properties of the PLA/HA scaffold are significantly higher than those of the PLA and b‐PLA‐HA scaffolds. Compared with the PLA and b‐PLA‐HA scaffolds, the attachment and growth of mouse embryonic osteoblasts cells (MC3T3‐E1) cultured on the PLA/HA scaffold significantly improve, due to most HA nanoparticles on the surface, resulting in a good and direct interaction between the cells and the scaffold. Therefore, the PLA/HA scaffold possesses great potential to be used as a tissue engineering scaffold.     

Miscibility of block copolymers of poly(ε‐caprolactone) and poly(ethylene glycol) with poly(3‐hydroxybutyrate) as well as the compatibilizing effect of these copolymers in blends of poly(ε‐caprolactone) and poly(3‐hydroxybutyrate)

Atactic poly(3‐hydroxybutyrate) (a‐PHB) and block copolymers of poly(ethylene glycol) (PEG) with poly(ε‐caprolactone) (PCL‐b‐PEG) were synthesized through anionic polymerization and coordination polymerization, respectively. As demonstrated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) measurements, both chemosynthesized a‐PHB and biosynthesized isotactic PHB (i‐PHB) are miscible with the PEG segment phase of PCL‐b‐PEGs. However, there is no evidence showing miscibility between both PHBs and the PCL segment phase of the copolymer even though PCL has been block‐copolymerized with PEG. Based on these results, PCL‐b‐PEG was added, as a compatibilizer, to both the PCL/a‐PHB blends and the PCL i‐PHB blends. The blend films were obtained through the evaporation of chloroform solutions of mixed components. Excitingly, the improvement in mechanical properties of PCL/PHB blends was achieved as anticipated initially upon the addition of PCL‐b‐PEG. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2600–2608, 2001     

Cytocompatibility of polyhydroxybutyrate modified by plasma discharge

Properties of pristine and Ar plasma‐treated polyhydroxybutyrate (PHB) was studied by different methods as a function of the plasma discharge power and the time from the plasma exposure. Surface polarity was determined by goniometry, surface morphology and roughness was examined by atomic force microscopy, the amount of ablated layer was determined by gravimetry. The chemical structure of the surface was determined by photoelectron spectroscopy. Ablation of the surface layer upon plasma treatment and chemical etching was studied by gravimetry. Cytocompatibility of pristine and modified PHB was studied on mouse embryonic fibroblasts (NIH 3T3). Plasma modification leads to an increase in PHB surface polarity. By aging the surface polarity spontaneously decreases. The amount of ablated layer increases with plasma exposure time and discharge power. The plasma‐treated PHB is slightly soluble in water and considerably in methanol. After the plasma treatment the surface morphology and roughness is mildly changed. The plasma treatment improves cell adhesion, proliferation, and spreading homogeneity on the PHB surface. POLYM. ENG. SCI., 54:1231–1238, 2014. © 2013 Society of Plastics Engineers