PCL Concentration Research Articles

Phase Equilibria, Diffusion and Structure in the Epoxypolycaprolactone System

Currently, there is no quantitative approach for the phase structure of cured thermoplastic systems modified with thermoplastic predicting. To solve this problem, we carried out the first stage of the study on a model polycaprolactone-epoxy oligomer (PCL-DGEBA) system. Using differential scanning calorimetry (DSC), refractometry and optical interferometry, a phase diagram for PCL-DGEBA mixtures was constructed, and the Flory-Huggins interaction parameters of PCL-DGEBA mixtures were calculated. The structure of PCL-DGEBA mixtures with different PCL content was analyzed by optical microscopy. The change in the structure formation mechanism with increasing PCL concentration was shown. The diffusion coefficients are calculated by the Motano-Boltzmann method. The values of the apparent activation energy of the viscous flow PCL and of self-diffusion of DGEBA are determined. The obtained data will be used for the in situ curing kinetics and phase equilibria in the diffusion zone investigations in order to develop a quantitative method for predicting the phase structure of cured systems.

Solvent selection and its effect on crystallization behavior of poly(ε-caprolactone) in electrospun poly(ε-caprolactone)/poly (lactic-co-glycolic acid) blend fibers

Biodegradable poly(ε-caprolactone) (PCL) and poly(lactic-co-glycolic acid) (PLGA) are both significant members of polyester family. In addition to their immense potential as tissue engineering scaffolds, disposable or short-lived biomedical materials could be also designed based on PCL/PLGA blends. The environmental degradation of such low-cost polyester-based blends strongly depend on the crystallization behavior and the crystal morphology of semicrystalline PCL component that correlate to the processing conditions of the blends. In this study, electrospinning, a non-equilibrium laboratory processing condition, was utilized to prepare 80:20 by mass PCL/PLGA blend fibers. Morphological study and thermal analysis were performed to study the crystallization behavior of PCL in the electrospun PCL/PLGA blends prepared using different solvents: chloroform (CHCl3), 2,2,2-trifluoroethanol (TFE), and CHCl3/TFE 1:1 vol mixture. PCL/PLGA fibers prepared using TFE or CHCl3/TFE solvents are significantly thinner than those prepared using CHCl3 solvent. The difference in the glass transition temperature PCL among these fibers is negligible, implying the poor miscibility of the 80:20 by wt. PCL/PLGA blend regardless of the solvent selected, due presumably to the relatively high PCL concentration. After removing PLGA phase using acetone, microscopic scale phase separation morphology was observed for thicker PCL/PLGA fibers (prepared using CHCl3 solvent). In contrast, for the thinner fibers (prepared using CHCl3/TFE mixture solvent), failure occurs and fibers broke cross-sectionally after acetone wash. Solvent vapor annealing experiment further unveiled the PCL lamellar network in the thicker fibers and the PCL shish-kebab in the thinner fibers, suggesting that for immiscible blends, the PCL crystallization mechanism strongly depends on the non-equilibrium laboratory processing conditions and less depends on the molecular characteristics of the second component.

Preparation and properties of nano-SiO2/lipase/polycaprolactone composite microsphere and its application in controlling the degradation of polylactic acid fiber membrane

Polylactic acid (PLA) fiber membrane needs to match the wound healing time when used as a medical adhesive membrane. In order to adjust the degradation cycle of PLA fiber, the composite microspheres of nano-SiO2/lipase/polycaprolactone (PCL) with degradation regulation function were designed and prepared. And then the composite microspheres were added into PLA fiber membrane to verify the degradation regulation function. The results showed that: the optimal preparation process of microspheres was obtained as follows: 5 mg/mL SiO2/lipase complex concentration, 10 mg/mL PCL concentration, 1000 r/min emulsification speed and 600 r/min curing speed. The amount of enzyme, loading in the microspheres, can be regulated in the range of 10.24%–11.29%. And the drug-loaded microspheres had a good sustained release effect. Finally, it was verified that the microspheres could accelerate the degradation rate of PLA fiber membrane.

Continuous Encapsulation of Vitamin E Using Polycaprolactone and Tween 20 in a Micro-Channel

Encapsulation of vitamin E is the preservation of the biological activities of vitamin E for various applications. In the first part of this research, factors affecting the batch encapsulation of vitamin E, including PCL concentration, the concentration of Tween 20, and the volumetric ratio of aqueous phase to organic phase were experimentally investigated. The Box-Behnken experimental design and response surface methodology were implemented to determine the optimal operating conditions of the batch encapsulation. At the optimal conditions, the percentage of vitamin E encapsulation (%EC) was 98.69%, using the PCL concentration, the Tween 20 concentration, and the volumetric ratio of aqueous phase to organic phase of 3.6 g/L, 0.6 g/L, and 0.9 mL: 1 mL, respectively. The second part is to enhance the productivity by applying the optimized formulation of vitamin E encapsulation in a continuous process using a micro-channel encapsulator. The effect of residence time was investigated. At the residence time of 1 s, the percentage of vitamin E encapsulation of 97.28% and the productivity of 153.61 mg/(mL∙min) were achieved.

Polymers for aluminium secondary batteries: Solubility, ionogel formation and chloroaluminate speciation

This work deals with the search of polymers apt for the preparation of solid-like chloroaluminate-based electrolytes. To accomplish this, the solubility and gelling ability of a large set of polymers in the deep eutectic solvent AlCl3:urea (uralumina) are studied, followed by the characterization of the electrochemical activity of the gels. The polymers are directly dissolved in urea:AlCl3 without auxiliary solvents following a fast and scalable gel preparation methodology previously reported for ultra-high molecular weight (UHMW) polyethylene oxide (PEO). The list of polymers studied includes diverse chemical structures, different thermal properties and different aggregation states at the mixing temperature of 70 °C, defined by the thermal stability of AlCl3:urea. To avoid a molecular weight influence on the ionogel rheological properties, polymers with molecular weight close to 100,000 g mol−1 have been chosen. The polymers considered include poly(ε-caprolactone) (PCL), poly(dimethyl siloxane) (PDMS), poly(vinyl pyrrolidone) (PVP), polyformal, thermoplastic polyurethanes, polymethacrylates, polyacetates and the elastomer SEBS. It was found that together with polyethylene oxide, only poly(ε-caprolactone) and poly(dimethyl siloxane) are soluble and produce gel electrolytes with AlCl3:urea. The solubility rules of polymers in chloroaluminates are discussed. The stripping/plating of Al and the ionic conductivity of PEO, PDMS and PCL ionogels are studied by cyclic voltammetry and impedance spectroscopy. PDMS proves to be as efficient as PEO to produce ionogels at low polymer concentration, that are also self-standing and electroactive, whereas a higher concentration of PCL is required to produce self-standing gels. The molecular structure of the ionogels and the modification of the chloroaluminate speciation is studied by vibrational spectroscopies, and supported by DFT calculations.

Real-Time and In Situ Evaluation of Phycocyanin Concentration in Spirulina platensis Cultivation System by Using Portable Raman Spectroscopy

Spirulina platensis can synthesize a large amount of phycocyanin, which had been developed as a health food. At the same time, Spirulina can absorb the nitrogen and phosphorus in wastewater and provide for its own growth. Here, we studied the optimal nitrogen and phosphorus supply for the Spirulina production process. For the first time, 405 nm portable Raman spectrometer was used to estimate phycocyanin content for real-time industrial applications. We obtained three Raman characteristic peaks of phycocyanin through density functional theory combined with home-built Raman spectrometer, which were 1272, 1337, and 1432 cm − 1 . There was a good linear correlation between the sum of the three peak intensities and the PCL concentration (y = 18.887x + 833.530, R 2 = 0.890 ). The least squares support vector machine model based on the characteristic peaks was used to estimate the concentration of phycocyanin and obtained good results with a correlation coefficient of prediction of 0.907 and residual predictive deviation of 3.357. The results can provide decision-making for integration of Spirulina effluent treatment and phycocyanin production and provide references for real-time Spirulina-based biorefinery applications.

Fabrication of carboxymethyl chitosan/poly(ε-caprolactone)/doxorubicin/nickel ferrite core-shell fibers for controlled release of doxorubicin against breast cancer

The coaxial electrospinning for producing core-shell nanofibers due to control the release profile of drug by the shell layer has been developed. N-carboxymethyl chitosan (CMC)-polyvinyl alcohol (core)/poly(ε-caprolactone) (PCL) (shell) nanofibers were produced via coaxial electrospinning. Doxorubicin (DOX) and nickel ferrite nanoparticles were incorporated into the nanofibers for controlled release of DOX against MCF-7 breast cancer. The minimum CMC/PCL fiber diameter was found to be 300 nm by optimizing of three variables including voltage to distance ratio (1.5–2.5 kV/cm), CMC concentration (4−6 wt.%) and PCL concentration (8−12 wt.%). The synthesized core-shell fibers were characterized using FTIR, XRD, SEM, and TEM analysis. The extended release and controlled release of DOX from core-shell nanofibers were achieved under physiological pH without external magnetic field (EMF) and acidic pH with EMF during 25 and 7 days, respectively. The maximum cytotoxicity of MCF-7 breast cancer cells was about 83 % using CMC/PCL/nickel ferrite 10 % nanofibers and EMF.

Well-Blended PCL/PEO Electrospun Nanofibers with Functional Properties Enhanced by Plasma Processing.

Biodegradable composite nanofibers were electrospun from poly(ε-caprolactone) (PCL) and poly(ethylene oxide) (PEO) mixtures dissolved in acetic and formic acids. The variation of PCL:PEO concentration in the polymer blend, from 5:95 to 75:25, revealed the tunability of the hydrolytic stability and mechanical properties of the nanofibrous mats. The degradation rate of PCL/PEO nanofibers can be increased compared to pure PCL, and the mechanical properties can be improved compared to pure PEO. Although PCL and PEO have been previously reported as immiscible, the electrospinning into nanofibers having restricted dimensions (250–450 nm) led to a microscopically mixed PCL/PEO blend. However, the hydrolytic stability and tensile tests revealed the segregation of PCL into few-nanometers-thin fibrils in the PEO matrix of each nanofiber. A synergy phenomenon of increased stiffness appeared for the high concentration of PCL in PCL/PEO nanofibrous mats. The pure PCL and PEO mats had a Young’s modulus of about 12 MPa, but the mats made of high concentration PCL in PCL/PEO solution exhibited 2.5-fold higher values. The increase in the PEO content led to faster degradation of mats in water and up to a 20-fold decrease in the nanofibers’ ductility. The surface of the PCL/PEO nanofibers was functionalized by an amine plasma polymer thin film that is known to increase the hydrophilicity and attach proteins efficiently to the surface. The combination of different PCL/PEO blends and amine plasma polymer coating enabled us to tune the surface functionality, the hydrolytic stability, and the mechanical properties of biodegradable nanofibrous mats.

Nano/micro-scale morphologies of semi-interpenetrating poly(ε−caprolactone)/tung oil polymer networks: Isothermal and non−isothermal crystallization kinetics

The isothermal and non-isothermal crystallization kinetics of pure poly(ε−caprolactone) (PCL) and its blends with crosslinked tung oil were investigated as a function of composition, crystallization temperature, and heating rate using differential scanning calorimetric (DSC). The PCL/tung oil semi-interpenetrating polymer networks of different compositions were prepared via cationic polymerization of tung oil in the presence of homogenous solutions of PCL. This unique and relatively new in-situ polymerization and compatibilization blending technique created nano/micro-scale morphologies that cannot be obtained with the traditional melt-processing and/or solvent casting methods. Blends with different miscibility, phase behaviors, and morphologies (miscible, partially miscible, and immiscible) were observed as a function of composition with a constant concentration of boron trifluoride diethyl etherate (BFE) cationic initiator. The morphology of the semi-interpenetrating polymer networks was performed using scanning electron microscopy (SEM). Miscible blends with a single Tg for PCL ≤ 10 wt.%. were observed. While, on the other hand, partially miscible blends with two distinct Tgs and nanoscale morphologies and average particle sizes as small as 100 nm were observed for blends with 20 ≤ PCL wt.% ≤ 30. Immiscible blends with microscale highly interconnected, co-continuous two-phase morphology and two distinct Tgs were detected for 50 wt.% PCL. Both isothermal and non-isothermal crystallization kinetics were strongly influenced by the different miscibility and morphology of the blends. The isothermal and non-isothermal crystallization kinetics of PCL/tung oil blends were analyzed on the basis of Avrami and modified Avrami approaches, respectively. A substantial decrease in the isothermal (longer half time) and non-isothermal (Tm shifted to lower temperature) crystallization kinetics was observed as the concentration of PCL increased in the blends up to 30 wt.% due to the partially miscibility of the blends in this composition range. In a contrast, for 50 wt.% PCL blend, a considerable increase in the crystallization kinetics (isothermal and non-isothermal) was detected due to the highly interconnected, co-continuous two-phase morphology.

Novel Poly(Caprolactone)/Epoxy Blends by Additive Manufacturing.

The aim of this work was the development of a thermoplastic/thermosetting combined system with a novel production technique. A poly(caprolactone) (PCL) structure has been designed and produced by fused filament fabrication, and impregnated with an epoxy matrix. The mechanical properties, fracture toughness, and thermal healing capacities of this blend (EP-PCL(3D)) were compared with those of a conventional melt mixed poly(caprolactone)/epoxy blend (EP-PCL). The fine dispersion of the PCL domains within the epoxy in the EP-PCL samples was responsible of a noticeable toughening effect, while in the EP-PCL(3D) structure the two phases showed an independent behavior, and fracture propagation in the epoxy was followed by the progressive yielding of the PCL domains. This peculiar behavior of EP-PCL(3D) system allowed the PCL phase to express its full potential as energy absorber under impact conditions. Optical microscope images on the fracture surfaces of the EP-PCL(3D) samples revealed that during fracture toughness tests the crack mainly propagated within the epoxy phase, while PCL contributed to energy absorption through plastic deformation. Due to the selected PCL concentration in the blends (35 vol %) and to the discrepancy between the mechanical properties of the constituents, the healing efficiency values of the two systems were rather limited.

Surface Epitaxial Crystallization-Directed Nanotopography for Accelerating Preosteoblast Proliferation and Osteogenic Differentiation.

Surface nanotopography provides a physical stimulus to direct cell fate, especially in the case of osteogenic differentiation. However, fabrication of nanopatterns usually suffers from complex procedures. Herein, a feasible and versatile method was presented to create unique nanosheets on a poly(ε-caprolactone) (PCL) substrate via surface epitaxial crystallization. The thickness, periodic distance, and root-mean-square nanoroughness of surface nanosheets were tunable by simply altering the PCL concentration in the growth solution. Epitaxial nanosheets possessed an identical composition as the substrate, being a prerequisite to revealing the independent effect of biophysical linkage on the osteogenic mechanism of the patterned surface. Preosteoblasts' response to the epitaxial nanosheets was examined in the aspect of preosteoblast proliferation and osteogenic differentiation. The expression of alkaline phosphatase, collagen type I, osteopontin, and osteocalcin as well as mineralization was significantly promoted by the epitaxial nanosheets. Acceleration of osteogenic differentiation was attributed to activating the TAZ/RUNX2 signaling pathway. The findings demonstrate that surface epitaxial crystallization is a feasible approach to design and construct nanotopography for bone tissue engineering.

Swelling and drug delivery kinetics of click-synthesized hydrogels based on various combinations of PEG and star-shaped PCL: influence of network parameters on swelling and release behavior

Polyethylene glycol (PEG)- and polyethylene glycol–polycaprolactone (PEG–PCL)-based hydrogels were synthesized with various compositions of prepolymers by using ROP and click chemistry methods. Relevant prepolymers were characterized by 1H NMR and FTIR spectroscopy. In order to study the influence of network parameters on swelling and release kinetics, experimental data were approximated by several mathematical models including zero order, first order, Higuchi and Korsmeyer–Peppas to determine the kinetics of swelling and diclofenac sodium release from hydrogels. The obtained results showed that the swelling and release data were best fitted to Korsmeyer–Peppas model. The results of the swelling study showed that the swelling properties of the hydrogels varied with the changes in the PEG molecular weights, as well as concentration of PCL. All of the hydrogels showed non-Fickian diffusion, but when PCL concentration increased and PEG molecular weights decreased, the n values were decreased and reached n = 0.5 (Fickian diffusion). The kinetics of diclofenac sodium release from hydrogels showed similar behavior so that in F hydrogels with the highest PCL concentration, the release mechanism fully changed from non-Fickian to Fickian diffusion. In other words, with increasing cross-link density and PCL concentration, the swelling degree and flexibility of networks decreased. Therefore, the swelling and release mechanism changed from non-Fickian to Fickian diffusion.

Electrospinning of polycaprolacton/chitosan core-shell nanofibers by a stable emulsion system

Electrospun core-shell structured nanofibers have got wide attention due to their excellent properties and potential applications. Encapsulated CS in PCL to form the core-shell structured fibers would be a festival way to expanding the applications of biopolymers. In this work, the electrospun core-shell polycaprolacone/chitosan (PCL/CS) composite nanofibers were prepared by a stable emulsion system. Different from other reported works, the surfactant-free and low toxic water-in-oil emulsion was selected to form the electrospinning precursor. The high stability of the emulsion was achieved by adjusting the volume ratio of the solvents and the concentration of the polymers. PCL/CS fibers with different core to shell ratios were obtained via the adjustment of the concentration of CS and PCL in emulsion system. The distribution of the composition in the fibers was analyzed by FT-IR, XRD, EDS, XPS and WCA. Further, intact ultrafine CS fibers with a mean diameter of 143 ± 49 nm could be obtained after the removal of PCL shell, indicating the low diffusivity between core and shell solutions during emulsion electrospinning process. This study provided a promising method to fabricate natural polymer fibers which were difficult to electrospin.

Fast and simple construction of composite films with renewable Eucommia ulmoides gum and Poly(ε-caprolactone)

Eucommia ulmoides gum (EUG) and Poly(ε-caprolactone) (PCL), a degradable, promising and “green” feedstock, can be used to fabricate composite films by a rapid and simple solution casting method, which have characteristics of degradability, hydrophobicity, strength, and toughness. Herein, EUG was extracted with petroleum ether from seed coats of Eucommia ulmoides and characterized with Fourier transform infrared (FT-IR) and nuclear magnetic resonance spectroscopy (NMR). The FT-IR and NMR revealed that the construction of the EUG and PCL of composite films are a physical blending process. Besides, the addition of PCL effectively enhances the thermal stability of composite films. The concentration of PCL is 0.84 wt% in composite film (P0.84 wt%), which exhibits an excellent elongation at break and energy density at break of 514.3% and 106.4 MJ/m3, respectively. The maximum tensile strength of the resultant film is 1.8 times higher than that of the control film. The hydrophobicity and water vapor barrier property of P0.84 wt% film is increased by 26.6% and 84.0%, respectively, than that of the control film. It is believed this work provided a rapid and simple strategy to fabricate degradable, strong, and tough film.

Two-photon polymerized poly(caprolactone) retinal cell delivery scaffolds and their systemic and retinal biocompatibility

Cell replacement therapies are often enhanced by utilizing polymer scaffolds to improve retention or direct cell orientation and migration. Obstacles to refinement of such polymer scaffolds often include challenges in controlling the microstructure of biocompatible molecules in three dimensions at cellular scales. Two-photon polymerization of acrylated poly(caprolactone) (PCL) could offer a means of achieving precise microstructural control of a material in a biocompatible platform. In this work, we studied the effect of various formulation and two-photon polymerization parameters on minimum laser power needed to achieve polymerization, resolution, and fidelity to a target 3D model designed to be used for retinal cell replacement. Overall, we found that increasing the concentration of crosslink-able groups decreased polymerization threshold and the size of resolvable features while increasing fidelity of the scaffold to the 3D model. In general, this improvement was achieved by increasing the number of acrylate groups per prepolymer molecule, increasing the acrylated PCL concentration, or decreasing its molecular weight. Resulting two-photon polymerized PCL scaffolds successfully supported human iPSC derived retinal progenitor cells in vitro. Sub-retinal implantation of cell free scaffolds in a porcine model of retinitis pigmentosa did not cause inflammation, infection or local or systemic toxicity after one month. In addition, comprehensive ISO 10993 testing of photopolymerized scaffolds revealed a favorable biocompatibility profile. These results represent an important step towards understanding how two-photon polymerization can be applied to a wide range of biologically compatible chemistries for various biomedical applications. Statement of SignificanceInherited retinal degenerative blindness results from the death of light sensing photoreceptor cells. To restore high-acuity vision a photoreceptor cell replacement strategy will likely be necessary. Unfortunately, single cell injection typically results in poor cell survival and integration post-transplantation. Polymeric biomaterial cell delivery scaffolds can be used to promote donor cell viability, control cellular polarity and increase packing density. A challenge faced in this endeavor has been developing methods suitable for generating scaffolds that can be used to deliver stem cell derived photoreceptors in an ordered columnar orientation (i.e., similar to that of the native retina). In this study we combined the biomaterial poly(caprolactone) with two-photon lithography to generate a biocompatible, clinically relevant scaffold suitable for retina cell delivery.

Study of the formation of biodegradable polycaprolactone particles using solvent evaporation method

Poly(ε-caprolactone) (PCL), an aliphatic polyester paved the way in the formation of biodegradable and biocompatible polymer particles in tissue engineering and drug delivery applications. The factors affecting in the preparation of PCL particles such as influences of the concentration of PCL, molecular weight and concentration of poly(vinylpyrrolidone) (PVP) stabilizer, and the reaction time on the characteristics of PCL particles were investigated. In the fabrication of PCL particles, size, morphology and stability of the polymer particles were tailored by varying the type and concentration of the stabilizer to the polymer, reaction time and stirring speed of the reaction. Additionally, formation of particles was also related to the amount of PCL and PVP concentration. The PCL particles possessed a spherical shape with the size ranges of 5-20 micron and stability increases with higher concentration of PVP while coagulation observed when PCL particles prepared with the low concentration of PVP. The change in the morphology and sizes of the PCL particle at different reaction conditions were evaluated by scanning electron microscopy (SEM) analysis.

Electrospun Tubular Scaffold for Stenting Application: A Proof of Concept

Bioresorbable Stents (BRS) offer enormous potential, however they must accomplish some specific requirements such as: (I) their manufacturing process must be precise; (II) degradation should have minimal toxicity; (III) their degradation rate should match the recovery rate of vascular tissue; (IV) ideally, they should induce rapid endothelialization to restore the functions of vascular tissue, but at the same time reduce the risk of restenosis; and (V) their mechanical behavior should comply with the medical requirements. With the recent inclusion of polymeric materials and additive manufacturing technologies, a new idea makes its way, Electrospun Tubular Scaffolds (ETS) for stenting process. Unlike current stents, ETS can present some advances (I) Longitudinal flexibility to help the placement of the stent, (II) Material matrix that mimic body tissue to help the rapid endothelization. The present work aims to study the feasibility of this new idea by analyzing how the electrospinning (ES) parameters affect the ETS properties. ETS were fabricated with a Rotational Electrospinning Machine. Poly (ε-caprolactone) (PCL) and Acetone were chosen as biopolymer and non-toxic solvent respectively. Electrospinning Voltage (Ev), Flow Rate (Fr), Polymer Concentration (PCL%), and Target Volume (Tv) were analyzed on the final ETS properties, namely, ETS Thickness (TK), ETS Maxim Radial Expansion (Mø), ETS Recoil Ratio (Rø). ETS thickness were measured by micrometer. Finally ETS radial behavior was studied by Radial Tests. Target Volume proved to be one of the most important parameter to obtain different ETS thickness, while Flow Rate and PCL Concentration has been the most important parameters to obtain a uniform ETS both longitudinally as radially. Regarding the radial behavior, ETS has proved their dependence of the fiber diameter obtained during the ES process. ETS have been able to expand radially a maximum of 67% with an average recoil ratio of 20% which left the ETS expand at 47%. These results allow us to conclude that ETS for stenting applications could be a possible solution for the current BRS problems.

Optimum parameters for the production of nano-scale electrospun polycaprolactone to be used as a biomedical material

Electrospun nano-polycaprolactone (PCL) is an ideal candidate for biomedical applications, as it mimics the extracellular matrix and possesses good biocompatibility, biodegradability and mechanical properties. Formic acid/acetic acid (FA/AA) and formic acid/acetone (FA/A) solvent systems were reported to be the safest solvents for the preparation of nanoscale electrospun polycaprolactone and they are also a common solvent with many natural polymers. In the present study a comparison between the electrospun fibers produced by the two systems was done. The optimum conditions for preparing PCL nanofibers were studied. The results indicated that finer fibers were found for formic acid/acetic acid in comparison with those produced by formic acid/acetone solvent system. In addition, it was found that optimum conditions for PCL nanofibers electrospinning were detected for 70:30 FA/AA solvent ratio with 15% PCL concentration and a tip to collector distance of 12.5 cm at 20 kV.

Preparation, characterization and hydrolytic degradation of PLA/PCL co-mingled nanofibrous mats prepared via dual-jet electrospinning

PLA/PCL co-mingled nanofibrous mats were prepared via multi-jet electrospinning. The concentration of PLA and PCL in the co-mingled mats were controlled by changing the flow rate of the two polymer solutions. The amount of PLA and PCL in the co-mingled nanofibrous mats was monitored by UV–Vis measurements through a colored dye added to PLA and by FTIR-ATR analysis. Morphology and mechanical properties of the nanofibrous mats were respectively examined by scanning electron microscopy (SEM) and tensile tests. Water contact angles measurements were also carried out in order to investigate the wettability of the materials. Finally, the hydrolytic degradation of the mats in buffer solution at pH 4, pH 7 and pH 10 were studied up to 50days.

Hydroxyapatite stabilized pickering emulsions of poly(ε-caprolactone) and their composite electrospun scaffolds

Electrospun fibrous scaffolds have advantageously being used in tissue engineering, however lack of functionalization during processing and use of organic solvents are two prime deterrents of the process. We report formation of hydroxyapatite (HA) functionalized poly(ε-caprolactone) (PCL) fibrous scaffolds via electrospinning of HA based Pickering emulsion. Role of HA as Pickering stabilizer for varying PCL concentration and water to oil volume ratio of emulsion was studied and emulsions were stabilized using HA in presence of a template polymer, poly(vinyl alcohol) (PVA). Effect of formulation and process variants was assessed on uniformity and fineness of fibrous scaffolds. HA functionalized PCL fibrous scaffolds were evaluated for their osteoblast cell growth efficacy and the scaffolds were found to have significantly higher cell proliferation than scaffolds made with PCL alone. Development of fibrous scaffolds using Pickering emulsions provided a unique method to introduce inorganic functionalities in organic fibrous matrix without using any conventional emulsifier at reduced organic solvent content.