PCL Surface Research Articles

Physicochemical, in vitro and in vivo evaluation of VEGF loaded PCL-mPEG and PDGF loaded PCL-Chitosan dual layered vascular grafts.

The present study has attempted to evaluate the endothelialization and smooth muscle regeneration efficiency of a novel dual-layer small-diameter vascular graft. Two types of layers (PCL-mPEG-VEGF and PCL-Chitosan-PDGF) were fabricated to find out the best layer giving endothelialization support for the lumen and unique contractile function for outer layer of blood vessels. Platelet-derived growth factor (PDGF) and chitosan were immobilized onto PCL surface by aminolysis-based surface modification technique. Besides, Poly (ethylene glycol) methyl ether (mPEG) and vascular endothelial growth factor (VEGF) were directly blended with PCL. Morphological analysis of membranes ensured consistency of average fibers diameter with native extracellular matrix. A favorable interaction of PCL-mPEG-VEGF with cow pulmonary endothelial cells (CPAEs) and PCL-Chitosan-PDGF with rat bone marrow mesenchymal stem cells (RBMSCs) was obtained during in vitro study. Controlled growth factor release patterns were found from both layers. Further, PCL-mPEG-VEGF exhibited endothelial markers expression properties from RBMSCs. Up-regulation of SMCs markers expression was significantly ensured by the PCL-Chitosan-PDGF membrane. Thus, PCL-mPEG-VEGF and PCL-Chitosan-PDGF were preferred as inner and outer layers respectively of a finally prepared tubular hybrid tissue engineered small diameter vascular graft. Finally, the dual-layer vascular graft was implanted onto a rat abdominal aorta model for 2 months. The extracted samples exhibited the presence of endothelial marker (ICAM 1) in the inner layer and smooth muscle cell marker (αSMA) in the outer layer as well as substantial amount of collagen deposition was observed in the both layers.

The Impact of Biomaterial Surface Properties on Engineering Neural Tissue for Spinal Cord Regeneration.

Tissue engineering for spinal cord injury (SCI) remains a complex and challenging task. Biomaterial scaffolds have been suggested as a potential solution for supporting cell survival and differentiation at the injury site. However, different biomaterials display multiple properties that significantly impact neural tissue at a cellular level. Here, we evaluated the behavior of different cell lines seeded on chitosan (CHI), poly (ε-caprolactone) (PCL), and poly (L-lactic acid) (PLLA) scaffolds. We demonstrated that the surface properties of a material play a crucial role in cell morphology and differentiation. While the direct contact of a polymer with the cells did not cause cytotoxicity or inhibit the spread of neural progenitor cells derived from neurospheres (NPCdn), neonatal rat spinal cord cells (SCC) and NPCdn only attached and matured on PCL and PLLA surfaces. Scanning electron microscopy and computational analysis suggested that cells attached to the material's surface emerged into distinct morphological populations. Flow cytometry revealed a higher differentiation of neural progenitor cells derived from human induced pluripotent stem cells (hiPSC-NPC) into glial cells on all biomaterials. Immunofluorescence assays demonstrated that PCL and PLLA guided neuronal differentiation and network development in SCC. Our data emphasize the importance of selecting appropriate biomaterials for tissue engineering in SCI treatment.

A Thermostable Lipase Isolated from Brevibacillus thermoruber Strain 7 Degrades Ɛ-Polycaprolactone.

The tremendous problem with plastic waste accumulation has determined an interest in biodegradation by effective degraders and their enzymes, such as thermophilic enzymes, which are characterized by high catalytic rates, thermostability, and optimum temperatures close to the melting points of some plastics. In the present work, we report on the ability of a thermophilic lipase, by Brevibacillus thermoruber strain 7, to degrade Ɛ-polycaprolactone (PCL), as well as the enzyme purification, the characterization of its physicochemical properties, the product degradation, and its disruptive effect on the PCL surface. The pure enzyme showed the highest reported optimum temperature at 55 °C and a pH of 7.5, while its half-life at 60 °C was more than five hours. Its substrate specificity referred the enzyme to the subgroup of lipases in the esterase group. A strong inhibitory effect was observed by detergents, inhibitors, and Fe3+ while Ca2+ enhanced its activity. The monomer Ɛ-caprolactone was a main product of the enzyme degradation. Similar elution profiles of the products received after treatment with ultra-concentrate and pure enzyme were observed. The significant changes in PCL appearance comprising the formation of shallower or deeper in-folds were observed after a week of incubation. The valuable enzyme properties of the lipase from Brevibacillus thermoruber strain 7, which caused a comparatively quick degradation of PCL, suggests further possible exploration of the enzyme for effective and environment-friendly degradation of PCL wastes in the area of thermal basins, or in thermophilic remediation processes.

The Composites of PCL and Tetranuclear Titanium(IV)–Oxo Complex with Acetylsalicylate Ligands—Assessment of Their Biocompatibility and Antimicrobial Activity with the Correlation to EPR Spectroscopy

In our research, we have focused on the biological studies on composite materials produced by the dispersion of titanium(IV)-oxo complex (TOC) with acetylsalicylate ligands in a poly(ε-caprolactone) (PCL) matrix, which is a biodegradable thermoplastic polymer increasingly used in the production of medical devices. Using PCL as a matrix for the biologically active compounds, such as antimicrobial agents, antibiotics or other active medical substances, from which these individuals can be gradually released is fully understable. Composites of PCL + nTOC (n = 10, 15 and 20 wt.%) have been produced and, in such a form, the biological properties of TOCs have been estimated. Direct and indirect cytotoxicity studies have been performed in vitro on L929 and human umbilical vein endothelial cells (HUVEC) cell lines. The antibacterial and antifungal activity of the PCL + TOC samples have been assessed against two Staphylococcus aureus (ATCC 6538 and ATCC 25923) reference strains, two Escherichia coli (ATCC 8739 and ATCC 25922) reference strains and yeast of Candida albicans ATCC 10231. Obtained results have been correlated with electron paramagnetic resonance (EPR) spectroscopy data. We could conclude that photoexcitation by visible light of the surface of PCL + nTOC composite foils lead to the formation of different paramagnetic species, mainly O-, which slowly disappears over time; however, their destructive effect on bacteria and cells has been proven.

Nanofiber electrospinning combined with rotary bioprinting for fabricating small-diameter vessels with endothelium and smooth muscle

Tissue engineering is a growing research area of great interest because it can produce bionic grafts to replace autologous tissue. Although many molding strategies have been tried, precellularization of small-diameter vascular grafts remains a research challenge. Here, a novel approach for fabricating bionic small-diameter vascular vessels is developed through combining nanofiber electrospinning and a specially-designed rotary bioprinter. Electrospun poly(ε-caprolactone) (PCL) provides good elasticity, and the electrospinning modification is beneficial for adhesion and functionalization of endothelial cells. A flat monolayer on the surface of PCL is formed after 7 days cultivation. Modification of the traditional three-dimensional (3D) bioprinter to increase rotation of the central axis used dual motors increase stability during the printing process. This allowed a uniform dense methacrylated gelatin (GelMA) structure containing smooth muscle cells to be bioprinted with the cells are arranged linearly along the horizontal axis of rotation. The two type cells maintain viability and proliferation in the structure during the process of cultivation. In addition, the bionic structure is superior to the natural blood vessel in anti-burst pressure and suture retention strength. This study may provide a new strategy for the development of bionic blood vascular tissue or other tubular structure.

In Vivo Evaluation of Gamma-Irradiated and Heparin-Immobilized Small-Diameter Polycaprolactone Vascular Grafts with VEGF in Aged Rats.

The effectiveness of small-diameter vascular grafts depends on their antithrombogenic properties and ability to undergo accelerated endothelialization. The extreme hydrophobic nature of poly(ε-caprolactone) (PCL) hinders vascular tissue integration, limiting its use in medical implants. To enhance the antithrombogenicity of PCL as a biomaterial, we grafted 2-aminoethyl methacrylate (AEMA) hydrochloride onto the PCL surface using gamma irradiation; developed a biodegradable heparin-immobilized PCL nanofibrous scaffold using gamma irradiation and N-(3-dimethylaminopropyl)-N′-ethyl carbodiimide hydrochloride/N-hydroxysuccinimide reaction chemistry; and incorporated vascular endothelial growth factor (VEGF) into the scaffold to promote vascular endothelial cell proliferation and prevent thrombosis on the vascular grafts. We assessed the physicochemical properties of PCL, heparin-AEMA-PCL (H-PCL), and VEGF-loaded heparin-AEMA-PCL (VH-PCL) vascular grafts using scanning electron microscopy, attenuated total reflection–Fourier transform infrared spectroscopy, toluidine blue O staining, and fibrinogen adsorption and surface wettability measurement. In addition, we implanted the vascular grafts into 24-month-old Sprague Dawley rats and evaluated them for 3 months. The H-PCL and VH-PCL vascular grafts improved the recovery of blood vessel function by promoting the proliferation of endothelial cells and preventing thrombosis in clinical and histological evaluation, indicating their potential to serve as functional vascular grafts in vascular tissue engineering.

Chitosan-coated poly (Ɛ-caprolactone) nanoparticles as acaricide carriers

Among many species of ticks that affect beef and dairy cattle, Rhipicephalus (Boophilus) microplus is the most common. It is responsible for heavy losses in milk and meat production. In this work we introduce nanostructures such as chitosan-poly-Ɛ-caprolactone (CS_PCL) nanoparticles to encapsulate amitraz (CS_PCLnp_Amitraz) and fluazuron (CS_PCLnp_Fluazuron) to treat tick infestations more effectively. The CS_PCLnp_Amitraz system has a final amitraz concentration of 1.0 mg/mL with a particle size of 275 ± 30 nm, surface charge of +43 ± 7 mV and entrapment efficiency of 77 ± 1%. The CS_PCLnp_Fluazuron system has a drug concentration of 0.5 mg/mL with a particle size of 295 ± 35 nm, surface charge of +45 ± 10 mV and entrapment efficiency of 89 ± 1%. Both systems reduced cytotoxicity on Balb/c 3T3 culture cells and were also active against R. microplus. Both molecules - amitraz and fluazuron – formed molecularly dispersed active compounds inside the core of the PCL polymer matrix. The PCL surface was composed of a chitosan layer, which influenced the stability of the steric nanoparticles at pH greater than 7. Both systems were stable at a saline concentration of 1.25 mol/L and at temperatures below 50 °C. Experiments conducted in vivo with CS_PCLnp_Amitraz, at doses of active ingredient equivalent to those of commercial products, showed decreased tick infestation for 21 days, as well as higher acaricide effect than observed for commercial products, which recommend a reapplication in 14 days. The acaricide effect was even stronger when CS_PCLnp_Amitraz (same dose as for commercial products) and CS_PCLnp_Fluazuron (half of the amount for commercial products) were administered together.

Highly controlled robotic customized gel functionalization on 3D printed PCL framework for bone tissue engineering

Despite their natural healing capacity, bone tissues face ample challenges during healing and reconstruction, especially when healing critical-size defects. 3D printing with thermoplastic bioresorbable materials offers great potential to develop patient-specific bone grafts but these are hydrophobic in nature and lead to poor implant-tissue integration. Therefore, this work aims to fabricate a patient-specific 3D printed, strong, macroporous, PCL core framework of a desired shape surrounded by a highly bioactive, open-cell, soft, microporous gel coating. A novel easy-to-reproduce robotic gel coating methodology is demonstrated to achieve a highly controlled customized gel coating that partially or totally fills the 3D printed pores or provides a thin layer over the PCL surface, and is optimised here for the best in vitro results. These bioresorbable hybrid scaffolds showed mechanical strength of ∼18 MPa, comparable to trabecular bone and significantly higher than natural-polymer hydrogel scaffolds, and simultaneously optimised gel coating demonstrated higher microporosity, improved bioactivity, and osteoconductivity that is comparable to natural-polymer hydrogels. These high-strength resorbable scaffolds possess multiscale porosity and multi functionalities ranging from nano-to sub-micron to micron to macro-scale that gives the overall customised CT-matched shape, and therefore offer rapid infiltration and mineralization by invading osteoblasts and osteocytes and early integration with the host tissue. This bone-like hierarchical structure makes it a potential candidate to treat light-load-bearing bone defects such as cysts in mandible and palate as well as moderate-load-bearing bone defects such as cleft palate, maxillofacial deformities, collapse of hard palate, and reconstructing orbital palate.

PH‐Sensitive Polymeric Poly (ϵ‐caprolactone) Core‐ Chitosan/Alginate Shell Particle System for Oral Insulin Delivery

AbstractOral administration of the drugs is considered as one of the most convenient and comfortable routes. However, an effective oral delivery of insulin still remains a challenging and elusive goal, due to bioavailability problem. The aim of our work is to develop a pH sensitive polymeric system for the oral delivery of insulin based on a poly (ϵ‐caprolactone) (PCL) core and shells of chitosan (CS) and alginate (ALG). The particles were prepared based on the double emulsion (water/oil/water) solvent evaporation method. The effect of blending Pluronic127 (F127) into the hydrophobic PCL matrix to improve its water permeability by increasing specific surface area. ALG have been chosen to provide the needed pH‐sensitivity to the system. However, to coat the PCL surface with this anionic ALG layer a cationic CS layer has been added. The influence of each of the CS and ALG layers on the nanoparticle's physiochemical properties as well as on the encapsulation efficiency and the drug release behavior of the nanoparticles was investigated. The results showed that CS and ALG shells increased the stability of the nanoparticles. The in vitro release studies using two different pH environments (1.2 and 6.8) to simulate the physiological conditions in the gastrointestinal tract (GIT) showed that, the particles have pH‐responsive release patterns. The kinetics studies showed that, the insulin release from all the particles formulations obey the Korsmeyer‐ Peppas kinetic model.

Improved cellular bioactivity by heparin immobilization on polycarbonate film via an aminolysis modification for potential tendon repair

Tendon repair was an important part during tendon to bone healing. In the present study, heparin molecules were immobilized on the aminolyzed PCL surface to improve the cellular bioactivity for potential tendon repair. The effects of heparin immobilization on protein adsorption behavior and cellular bioactivity of NIH3T3 and ATDC5 cells were investigated. The results were shown as follows:1.Heparin molecules could be effectively immobilized on the PCL surface through an aminolysis modification.2.PCL films exhibited a more negative surface after heparin immobilization. The existence of heparin enhanced the adsorption of proteins.3.Heparin immobilized PCL sample improved the attachment and proliferation of NIH3T3 and ATDC5 cells, also enhanced the secretion of collagen and glycosaminoglycans.

Skeletal myotube formation enhanced through fibrillated collagen nanofibers coated on a 3D-printed polycaprolactone surface

This work focused on considering the cellular responses of the growth and differentiation of myoblasts, C2C12, on fibrillated collagen-coated poly(ε-caprolactone) (PCL) surfaces. Through a fibrillation processing window using NaCl and collagen weight fractions, collagen fibril coating density can be controlled. Three different collagen-fibril densities coated on PCL strut were used to investigate the effects of the collagen fibril on the myoblast activities. After physical and cellular analyses of the scaffolds, such as surface morphology, fibronectin absorption, wettability, and mechanical properties, the rate of cell growth and the proficiency of the myoblasts to develop skeletal myotubes were evaluated. Based on the results, although the coated collagen nanofibers were randomly distributed, the fibrillated collagen layer with the appropriate density on the PCL surface promoted a greater myotube formation than that of the control, which had no fibrillated collagen. In particular, relatively higher densities of collagen fibril showed significantly greater myotube formation than those of the control (not-fibrillated collagen-coated on the PCL surface) and lower density of collagen fibril.

Structural control and characterization of hierarchically structured fibrous scaffolds

To prepare hierarchically structured fibrous scaffolds with different morphologies, and to explore the additional dimensionality for tuning the physicochemical properties of the scaffolds and the effect of their hemocompatibility and cytocompatibility. Electrospinning poly (e-caprolactone) (PCL)/polyvinylpyrrolidone (PVP) bicomponent fibers (PCL∶PVP mass ratios were 8∶2 and 5∶5 respectively), and the surface porous fibrous scaffolds were prepared by extracting PVP components. The scaffolds were labeled PCL-P8 and PCL-P5 respectively according to the mass ratio of polymer. In addition, shish-kebab (SK) structured scaffolds with different kebab sizes were created by solution incubation method, which use electrospun PCL fibers as shish while PCL chains in solution crystallizes on the fiber surface. The PCL fibrous scaffolds with smooth surface was established as control group. The hierarchically structured fibrous scaffolds were characterized by field emission scanning electron microspore, water contact angle tests, and differential scanning calorimeter (DSC) experiments. The venous blood of New Zealand white rabbits was taken and hemolysis and coagulation tests were used to characterize the blood compatibility of the scaffolds. The proliferation of the pig iliac artery endothelial cell (PIEC) on the scaffolds was detected by cell counting kit 8 (CCK-8) method, and the biocompatibility of the scaffolds was evaluated. Field emission scanning electron microscopy showed that porous morphology appeared on the surface of PCL/PVP bicomponent fibers after extracting PVP. In addition, SK structure with periodic arrangement was successfully prepared by solution induction, and the longer the crystallization time, the larger the lamellar size and periodic distance. The contact angle and DSC measurements showed that when compared with smooth PCL fiber scaffolds, the crystallinity of PCL surface porous fibrous scaffolds and PCL-SK fibrous scaffolds increased, while the hydrophobicity of PCL-SK fibrous scaffolds increased, but the hydrophobicity of PCL porous scaffolds did not change significantly. The hemolysis test showed that the hemolysis rate of PCL surface porous fibrous scaffolds and PCL-SK fibrous scaffolds was higher than that of PCL fibrous scaffolds. According to American Society of Materials and Tests (ASTM) F756-08 standard, all scaffolds were non-hemolytic materials and were suitable for blood contact materials. Coagulation test showed that the coagulation index of PCL surface porous fibrous scaffolds and PCL-SK fibrous scaffolds was higher than that of PCL fibrous scaffolds at 5 and 10 minutes of culture. CCK-8 assay showed that both hierarchically structured fibrous scaffolds were more conducive to PIEC proliferation than PCL fibrous scaffold. Based on electrospinning technology, solution-induced and blend phase separation methods can be used to construct multi-scale fiber scaffolds with different morphologies, which can not only regulate the surface physicochemical properties of the scaffolds, but also have good blood compatibility and biocompatibility. The hierarchically structured fibrous scaffolds have high application potential in the field of tissue engineering.

Incorporating PCL nanofibers with oyster shell to improve osteogenic differentiation of mesenchymal stem cells

Electrospun poly (Ɛ-caprolactone) (PCL) has been widely utilized as a biomedical scaffold material to regenerate damaged tissues. However, an electrospun scaffold made from PCL can have some drawbacks such as lack of surface bioactivity, low cell adhesion, as well as osteoinduction, which often make it unsuitable as an implant. Moreover, such a scaffold can produce acidic degradations that cause an inflammatory response at the implantation site. To overcome these negative aspects, composite electrospun nanofiber scaffolds of PCL/oyster shell (OS) were developed in this study. Then, surface morphology and chemistry of the given scaffolds were characterized. As well, tensile strength and surface hydrophilicity were evaluated. The osteogenic proliferation and differentiation potentials of these scaffolds were further evaluated through determining basic osteogenic markers using human adipose tissue derived from mesenchymal stem cells. The results revealed that the scaffolds fabricated had a very good surface property and better tensile strength than pristine PCL ones. The osteogenic proliferation and differentiation potentials were also reported to be better than those in pristine PCL scaffolds. Hence, the presence of OS could enhance PCL surface properties and bioactivity. Therefore, PCL/OS composite scaffolds developed in this study were assumed cost-effective and ideal which would offer promising alternatives for bone tissue engineering applications.

Cold atmospheric plasma as a promising approach for gelatin immobilization on poly(\u03b5-caprolactone) electrospun scaffolds

Poly(Ɛ-caprolactone) (PCL) is a biocompatible polymer with a high potential to be used in tissue engineering especially in tight tissues. In the current study, cold atmospheric plasma (CAP) is used as a promising method for immobilization of gelatin as a functional biomacromolecule on PCL nanofibrous substrates. The CAP surface modification leads to oxidation of chemical groups existing on the PCL surface without doing any damage to the bulk properties of biomaterials for gelatin biomacromolecule grafting. The water contact angle (WCA) of the CAP-treated surface and gelatin-grafted PCL using CAP indicates an effective increment in the hydrophilicity of the PCL surface. Also to achieve the highest levels of gelatin grafting on the PCL surface, two different grafting methods and gelatin concentration diversity are utilized in the grafting process. The immobilization of gelatin biomacromolecules onto the CAP surface-modified PCL nanofibers is investigated using scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The gelatin-modified PCL substrates revealed uniform nanofibrous morphology with increased average fiber diameter. The results of FTIR spectra, including hydroxyl groups, NH groups, and amide II of gelatin-grafting peaks, confirm the gelatin immobilization on the surface of nanofibers. The metabolic activity of cultured mesenchymal stem cells (MSCs) on the surface-modified scaffolds is evaluated using MTT analysis (P ≤ 0.05). The results of metabolic activity and also SEM and DAPI staining observations indicate proper attachment on the surface and viability for MSCs on the surface-immobilized nanofibrous scaffolds. Therefore, CAP treatment would be an effective method for biomacromolecule immobilization on nanofibers towards the enhancement of cell behavior.

A Simple Method to Functionalize PCL Surface by Grafting Bioactive Polymers Using UV Irradiation

BackgroundPolycaprolactone (PCL) is a biodegradable polymer which is used in tissue engineering applications thanks to its many favorable characteristics. However, PCL surfaces are known as hydrophobic leading to a lack of favorable cell response. To overcome this problem, PCL surfaces will undergo a surface functionalization by grafting bioactive polymers bearing ionic groups. ObjectiveOur laboratory has demonstrated that the grafting of bioactive polymers onto biomaterials can improve cell and antibacterial response. The objective of this work is to functionalize PCL surfaces by the grafting of a bioactive polymer. MethodsThe grafting of an ionic polymer poly(sodium styrene sulfonate) (polyNaSS), using UV irradiation on PCL surfaces was carried out in a two-steps reaction process. PCL surfaces were (1) chemically oxidized in order to allow the formation of (hydro)peroxide species. (2) Then immersed in a sodium styrene sulfonate (NaSS) solution and placed under UV irradiation to induce the decomposition of (hydro)peroxides to form radicals able to initiate the polymerization of the NaSS monomer. Various parameters, such as polymerization time, the effect of the surface activation, lamp power and monomer concentration were investigated in order to optimize the yield of polyNaSS grafting. The amount of polyNaSS grafted onto PCL surfaces was first determined by toluidine blue colorimetric method and characterized by contact angle measurement, Fourier-transform infrared spectra recorded in attenuated total reflection mode (ATR-FTIR), scanning electron microscopy with Oxford energy dispersive spectroscopy (SEM-EDS). ResultsVarious techniques showed that the grafting of ionic polymer polyNaSS bearing sulfonate groups was successful by using radicals from (hydro)peroxides able to initiate the radical polymerization of ionic monomers onto PCL surfaces. ConclusionWe developed a new approach of radical grafting which allows us to successfully graft bioactive polymer polyNaSS covalently to PCL surfaces using UV irradiation.

Characterization of nano-structured poly(ε-caprolactone) membranes with DNA-doped polypyrrole via sonication-induced layer-by-layer assembly

In this study, the formation of conductive nano-structured polypyrrole (PPy) on electrospun poly(ɛ-caprolactone) (PCL) nanofibers was successfully achieved using a DNA dopant (PCL/DNA-PPy) via sonication-induced layer-by-layer assembly. After PPy containing positive charges was accumulated on PCL, DNAs with negative charges deposited such that they were evenly distributed. The resulting PCL/DNA-PPy nanomembrane exhibited increased fiber diameter (PCL/DNA-PPy 5LBL: 328.11 ± 48 nm) and deformation morphology compared to pure PCL (average fiber diameter of 247.25 ± 32 nm, fibrous uniform morphology), as observed using scanning electron microscopy and atomic force microscopy. As the number of layers increased, the crystallinity of PCL/DNA–PPy nanomembranes decreased, as observed using X-ray diffraction. It was observed that the PPy-DNA deposited on the surface of PCL connected to form a nano-sheath and significantly increased the thermal stability of PCL. Moreover, the contact angle of the PCL/DNA-PPy nanomembrane (contact angle of pure PCL: 79.3 ± 1.2°) demonstrated its high hydrophilicity. The results indicate that the composites showed very good survival in a cytotoxicity test on U-118 glioma cells and excellent electrical conductivity (the highest value was 1.1 × 10−3 S/m). The manufactured PCL/DNA–PPy nanomembranes are considered to be promising materials for applications in the scaffold, sensor, and electronic fields.

Direct and effective preparation of core-shell PCL/PEG nanoparticles based on shell insertion strategy by using coaxial electrospray

It is of great significance to efficiently prepare core-shell nanoparticles. In this study, we directly and efficiently prepared core-shell structured PCL/PEG nanoparticles based on shell insertion strategy by using coaxial electrospray. The key points to ensure the success of this new strategy include: the preparation of PCL particles with size less than 100 nm which worked as core structure; the insertion of PEG into PCL surface which worked as shell structure. We directly fabricated PCL particles with size less than 100 nm by using shell evaporation coaxial electrospray method. It means that PCL nanoparticles could be prepared and used as core structure through coaxial electrospray method. PEG solution worked as shell layer, PCL solution worked as core layer, PCL/PEG core shell structured microparticles were obtained through coaxial electrospray technique. Because of the solvent diffusion during the coaxial electrospray process, PEG could insert into PCL when TFE was used as the solvent of both core and shell layer. Then, after removing uninserted PEG, PCL/PEG nanoparticles with core-shell structure were fabricated successfully. The core-shell structured nanoparticles were stored at 4 °C and were stable without changing size for at least 7 days. This method can easily prepare core-shell structured nanoparticle with different size by changing the injection speed of PCL solution.

Maltose conjugation to PCL: Advanced structural characterization and preliminary biological properties

The emerging trends in regenerative medicine rely among others on biomaterial-based therapies, with the use of biomaterials as a central delivery system for biochemical and physical cues to manipulate transplanted or ingrowth cells and to orchestrate tissue regeneration. Cell adhesion properties of a biomaterial strongly depend on its surface characteristics.Among others poly(ε-caprolactone) (PCL) is a biocompatible and biodegradable material with low cytotoxicity that is widely adopted as synthetic polymer in several applications. However, it is hydrophobic, which limits its use in tissue engineering. In order to improve its hydrophilicity and cellular compatibility, PCL surface was grafted with maltose through a two-step procedure in which controlled aminolysis of PCL ester bonds by hexanediamine was followed by reductive amination with the carbohydrate reducing end. The modified PCL surface was then characterized in detail by x-ray Photoelectron Spectroscopy (XPS) and Near Edge x-ray Absorption Fine Structure (NEXAFS) spectroscopies. In addition, the biocompatibility of the proposed biomaterial was investigated in preliminary biological assays.

Effect of low-temperature plasma treatment of electrospun polycaprolactone fibrous scaffolds on calcium carbonate mineralisation.

This article reports on a study of the mineralisation behaviour of CaCO3 deposited on electrospun poly(ε-caprolactone) (PCL) scaffolds preliminarily treated with low-temperature plasma. This work was aimed at developing an approach that improves the wettability and permeability of PCL scaffolds in order to obtain a superior composite coated with highly porous CaCO3, which is a prerequisite for biomedical scaffolds used for drug delivery. Since PCL is a synthetic polymer that lacks functional groups, plasma processing of PCL scaffolds in O2, NH3, and Ar atmospheres enables introduction of highly reactive chemical groups, which influence the interaction between organic and inorganic phases and govern the nucleation, crystal growth, particle morphology, and phase composition of the CaCO3 coating. Our studies showed that the plasma treatment induced the formation of O- and N-containing polar functional groups on the scaffold surface, which caused an increase in the PCL surface hydrophilicity. Mineralisation of the PCL scaffolds was performed by inducing precipitation of CaCO3 particles on the surface of polymer fibres from a mixture of CaCl2- and Na2CO3-saturated solutions. The presence of highly porous vaterite and nonporous calcite crystal phases in the obtained coating was established. Our findings confirmed that preferential growth of the vaterite phase occurred in the O2-plasma-treated PCL scaffold and that the coating formed on this scaffold was smoother and more homogenous than those formed on the untreated PCL scaffold and the Ar- and NH3-plasma-treated PCL scaffolds. A more detailed three-dimensional assessment of the penetration depth of CaCO3 into the PCL scaffold was performed by high-resolution micro-computed tomography. The assessment revealed that O2-plasma treatment of the PCL scaffold caused CaCO3 to nucleate and precipitate much deeper inside the porous structure. From our findings, we conclude that O2-plasma treatment is preferable for PCL scaffold surface modification from the viewpoint of use of the PCL/CaCO3 composite as a drug delivery platform for tissue engineering.

Degradation of Poly(ε-caprolactone) and bio-interactions with mouse bone marrow mesenchymal stem cells

Bio-inspired scaffolds in bone tissue engineering using multipotential mesenchymal stem cells grow at a rapid rate found its successful use in orthopedic injury treatment. Poly(ε-caprolactone)/PCL is widely used in medical devices, tissue engineering, and drug delivery systems. Most desirable property of biodegradable polymer to be employed in medical application is synchronization of degradation with functional tissue regeneration. Limited studies have incorporated the degradation kinetics and implication of degradation products of pure unmodified PCL. The present study analyzes short term in vitro degradation profile of PCL films in physiological condition. The study reports weight loss, changes in molecular weight distribution and morphological variation in PCL thin film over a period of 90-day degradation. When the degradable material is in contact with host tissue, there exists robust and dynamic microenvironment controlling the cell functionality. To comprehend the biocompatibility aspects of polymer material, the study considered mouse bone marrow mesenchymal stem cells (BMSCs) as model system mimicking in vivo. There was no indication of toxicity revealed with MTT, LDH leakage, direct contact assay and clonogenic assay. Absence of oxidative stress and apoptosis denotes BMSCs functional integrity sustained upon exposure to PCL degradation products. Cell cycle analysis and DNA ladder assay confirmed cell survival and genomic stability. The study revealed that the topography of pure unmodified PCL surface is suitable for cell adhesion. It was also observed that the viability of differentiated cells (osteoblasts) was maintained in presence of PCL extract. Furthermore, polymer and its degradation products were proved to be hemocompatible. These results synergistically suggest that pure unmodified PCL and its degradation products are non-toxic at molecular level.