Polycaprolactone Content Research Articles

Physical, chemical, and biological property of silk reinforced polycaprolactone composites for bone tissue engineering

To develop a biodegradable implantable bone material with compatible mechanics with the bone tissue, providing a new biomaterial for clinical bone repair and regeneration. Silk reinforced polycaprolactone composites (SPC) containing 20%, 40%, and 60% silk were prepared by layer-by-layer assembly and hot-pressing technology. Macroscopic morphology was observed and microstructure were observed by scanning electron microscopy, compressive mechanical properties were detected by compression test, surface wettability was detected by surface contact angle test, degradation of materials was observed after soaking in PBS for 180 days, and proliferation of MC3T3-E1 cells was detected by cell counting kit 8 assay. Six Sprague Dawley rats were subcutaneously implanted with polycaprolactone (PCL) and 20%-SPC, respectively. Masson staining was used to analyze the in vivo degradation behavior and vascularization effect within 180 days. The pore defects of the three SPC sections were relatively few. In the range of 20% to 60%, as the silk content increased and the PCL content decreased, the interlayer spacing of silk fabric decreased, and the fibers almost covered the entire cross-section. The compressive modulus and compressive strength of SPC showed an increasing trend, and the compressive modulus of 60%-SPC was slightly lower than that of 40%-SPC. There were significant differences in compressive modulus and compressive strength between the materials ( P<0.05). In vitro simulated fluid degradation experiments showed that the mass loss of the three types of SPC after 180 days of degradation was within 5%, with the highest mass loss observed in 60%-SPC. The differences in mass loss between the materials were significant ( P<0.05). As the silk content increased, the static water contact angle of each material gradually decreased, and all could promote the proliferation of MC3T3-E1 cells. The subcutaneous degradation experiment in rats showed that 20%-SPC began to degrade at 30 days after implantation, and material degradation and vascularization were significant at 180 days, which was in sharp contrast to PCL. SPC has the mechanical and hydrophilic properties that are compatible with bone tissue. It maintains its mechanical strength for a long time in a simulated body fluid environment in vitro, and achieves dynamic synchronization of material degradation, tissue regeneration, and vascularization through the body's immune regulation mechanism in vivo. It is expected to provide a new type of implant material for clinical bone repair.

Additive manufacturing of polylactic acid scaffolds dip-coated with polycaprolactone for bone tissue engineering

Bone tissue engineering aims to create scaffolds that support bone regeneration, addressing the needs of approximately 1.71 billion people with bone structure problems worldwide. This study explores the fabrication and characterization of 3D-printed polylactic acid (PLA) scaffolds dip-coated with polycaprolactone (PCL), producing complex geometries with interconnected pores, specifically RoundBar Sphere and RoundBar Cube. The scaffolds were then coated with PCL solutions of 0.5 % and 1 % concentrations, applying up to three layers. Surface topology analysis indicated that PCL coating slightly reduced pore size (1150 µm to 900) while improving coverage and integrity. After coating, Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of PCL on scaffold surfaces (characteristic bands at 1726, 1175 and 728 cm−1), whose a better coverage was obtained with more layers and higher concentrations of PCL. Coated scaffolds showed not significant change in compressive strengths (2–12 MPa), remaining suitable for trabecular bone applications. Hemolysis assays of the 3D scaffolds promoted non-hemolytic properties (0 % hemolysis), ensuring their blood compatibility. Metabolic activity (>70 %) and live/dead cell assays in human dermal fibroblasts (HDF) exhibited biocompatibilities for all samples, with coated scaffolds promoting enhanced cell proliferation compared to uncoated ones. Additionally, osteoblast metabolic activity (>90 %) and osteoblasts scratch assay demonstrated coated scaffolds promoted an area reduction of 1.36 and 1.53-fold higher than the control group and uncoated scaffold, respectively. In short, these coated scaffolds are promising candidates for bone tissue engineering and bone repair applications.

Uridine-Loaded Polycaprolactone Nanofiber Mats as a Novel Wound Dressing

In the current study, a novel wound dressing material for an effective wound healing was developed by loading Uridine (URD), an endogenous compound known for its regenerative properties, into polycaprolactone (PCL) nanofibers. Initially, PCL nanofibers without URD were fabricated from different PCL solutions (7, 8, 10 and 11% w/w) by electrospinning and optimum PCL concentration (10% w/w) for URD loading was determined. After loading URD at different concentrations (0.1, 0.5 and 1% w/w) into 10% PCL solution, PCL/URD nanofibers were electrospun. Structural characteristics, release kinetics as well as in vitro and in vivo effects of the PCL/URD nanofibers were studied and in vivo effects were compared with a conventional wound dressing material. Loading URD increased nanofiber diameters from 248 to 509 nm and decreased contact angles from 123.76° to 94.3° with increasing URD concentrations. URD showed a burst release in the first 60 min following a more gradual release up to the 5th day which best fitted with Korsmeyer–Peppas model. PCL/URD mats provided enhanced viability in vitro in MTT assay using mouse L929 fibroblast cell line. Furthermore, in vivo wound closure studies revealed an immediate and robust wound healing in rats treated with PCL/URD mats compared to PCL mats without URD as well as the conventional wound dressing material. These data suggest that URD-loaded PCL nanofiber mats are promising materials as wound dressing.Graphical abstract

The Effect of Polycaprolactone Polymer Degradation in Compost on Seed Germination

Abstract Polycaprolactone (PCL) is a biodegradable synthetic polymer derived from petroleum that can be broken down by microorganisms. Due to its low melting point, it is suitable for composting. PCL has various applications, including in medicine and agriculture. This study investigates whether PCL degradation in compost affects seed germination. The study tested the effect of PCL extracts from compost with different temperatures and concentrations on the germination of seeds from four edible plant species: cress, lettuce, mustard, and rocket. The results showed that at low temperatures and low PCL concentrations, there was no effect on seed germination. However, at higher temperatures (55°C) and higher PCL concentrations (10% and 5%), there was a signiIicant negative effect on seed germination, with no germination in 10% PCL treatments and only 53.3% germination in 5% PCL treatments. This inhibition was observed across all plant species. The study concludes that high temperatures and high PCL concentrations in compost can negatively impact seed germination.

Healing Process Affected by Morphology of PCL/Epoxy Blends

In this study, a blend of epoxy and polycaprolactone (PCL) was prepared to investigate its ‎properties. Different weight percentages of thermoplastic PCL (0.25, 0.5, 1, 2 wt%) were ‎combined with epoxy coatings. The final morphology revealed PCL scattered as spherical ‎particles within the epoxy phase, which was functioning as a continuous matrix. The coating ‎showed toughness and rigidity when it had fully cured. The PCL phase had a special behavior ‎when heated, called "bleeding," in which it filled any open surfaces of its own volition. By ‎using molten PCL to fill in cracks, this property can be used for self-healing applications. The ‎self-healing efficacy of blends with different PCL contents was assessed. The self-healing ‎efficacy of the various mixes was determined by dividing the width of the self-healed crack by ‎the width of the original crack. The results showed that the highest thermal-mending efficiencies, ‎reaching 100%, were achieved with a PCL/epoxy blend containing co-continuous phases, ‎specifically at a 1 wt.% PCL content. Fourier-transform infrared (FTIR) analysis indicated that ‎there was physical interaction between the epoxy and PCL phases, but no chemical bonding ‎occurred between them.‎

Electrospinning of protein based egg albumin nanofibers

In this study, Polycaprolactone (PCL)-based nanofibers containing protein-based egg albumin (EA) were produced via electrospinning. Before the electrospinning process, solutions containing EA at different concentrations were prepared, and the conductivity, viscosity, and surface tension values of these solutions were determined. PCL was used as a carrier polymer in the solutions, and the PCL concentration was kept constant at 7 wt%. EA was present in all six solutions at concentrations of 0, 1, 3, 5, 7, and 9 wt%, respectively. All nanofibers were characterized morphologically, chemically, and thermally. The viscosity, conductivity, and surface tension of the solutions increased with the concentration increasement of EA. Afterward, the electrospinning process was achieved under optimum process parameters and ambient conditions. Uniform, smooth, and homogeneous nanofibers were produced via electrospinning. The Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FT-IR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC) analysis were performed as part of characterization studies. Besides, in-vitro EA release behavior from nanofibers was determined via UV–vis spectrophotometry. When the SEM images were examined, the particles of EA were seen on the web surface. According to the results of chemical and thermal analysis, the presence of PCL and EA was proven in the produced nano web. XRD analysis revealed a decrease in the crystallinity of the protein-based nanofiber with the addition of EA. According to in-vitro analysis results, it was determined that EA showed immediate release from PCL-based nanofibers. In-vitro cytotoxicity test on L929 fibroblasts via MTT assay showed that the prepared nanofibers were not toxic to the cells.

Optimization of Polycaprolactone and Type I Collagen Scaffold for Tendon Tissue Regeneration.

Introduction Collagen synthesis is vital for restoring musculoskeletal tissues, particularly in tendon and ligamentous structures. Tissue engineering utilizes scaffolds for cell adhesion and differentiation. Although synthetic scaffolds offer initial strength, their long-term stability is surpassed by biological scaffolds. Combining polycaprolactone (PCL) toughness with collagen in scaffold design, this study refines fabrication via electrospinning, aiming to deliver enduring biomimetic matrices for widespread applications in musculoskeletal repair. Methods Electrospinning employed four solutions with varied collagen and PCL concentrations, dissolved in chloroform, methanol, and hexafluoro-2-propanol. Solutions were combined to yield 60 mg/mL concentrations with different collagen/PCL ratios. Electrospinning at 12-14kV voltage produced scaffolds, followed by vacuum-drying. Collagen coating was applied to PCL and 15% collagen/PCL scaffolds using a 0.1% collagen solution. SEM characterized fiber morphology, tensile testing was conducted to determine the mechanical properties of the scaffold, and Fourier-transform infrared (FTIR) spectroscopy analyzed scaffold composition. Atomic force microscopy (AFM) analyzed the stiffness properties of individual fibers, and a finite element model was developed to predict the mechanical properties. Cell culture involved seeding human bone marrow mesenchymal stem cells onto scaffolds, which were assessed through Alamar Blue assay and confocal imaging. Results Various scaffolds (100% PCL, PCL-15% collagen, PCL-25% collagen, PCL-35% collagen) were fabricated to emulate the extracellular matrix, revealing collagen's impact on fiber diameter reduction with increasing concentration. Tensile testing highlighted collagen's initial enhancement of mechanical strength, followed by a decline beyond PCL-15% collagen. FTIR spectroscopy detected potential hydrogen bonding between collagen and PCL. A finite element model predicted scaffold response to external forces which was validated by the tensile test data. Cell viability and proliferation assays demonstrated successful plating on all scaffolds, with optimal proliferation observed in PCL-25% collagen. Confocal imaging confirmed stem cell integration into the three-dimensional material. Collagen coating preserved nanofiber morphology, with no significant changes in diameter. Coating of collagen significantly altered the tensile strength of the scaffolds at the macro scale. AFM highlighted stiffness differences between PCL and collagen-coated PCL mats at the single fiber scale. The coating process did not significantly enhance initial cell attachment but promoted increased proliferation on collagen-coated PCL scaffolds. Conclusion The study reveals collagen-induced mechanical and morphological alterations, influencing fiber alignment, diameter, and chemical composition while emphasizing scaffolds' vital role in providing a controlled niche for stem cell proliferation and differentiation. The optimization of each of these scaffold characteristics and subsequent finite element modeling can lead to highly repeatable and ideal scaffold properties for stem cell integration and proliferation.

Impact of morphological features and chemical composition of tendon biomimetic scaffolds on immune recognition via Toll-like receptors.

Tendinopathies are a major worldwide clinical problem. The development of tendon biomimetic scaffolds is considered a promising, therapeutic approach. However, to be clinically effective, scaffolds should avoid immunological recognition. It has been well described that scaffolds composed of aligned fibers lead to a better tenocyte differentiation, vitality, proliferation and motility. However, little has been studied regarding the impact of fiber spatial distribution on the recognition by immune cells. Additionally, it has been suggested that higher hydrophilicity would reduce their immune recognition. Herein, polycaprolactone (PCL)-hyaluronic acid (HA)-based electrospun scaffolds were generated with different fiber diameters (in the nano- and micro-scales) and orientations as well as different grades of wettability and the impact of these properties on immunological recognition has been assessed, by means of Toll-like receptor (TLR) reporter cells. Our results showed that TLR 2/1 and TLR 2/6 were not triggered by the scaffolds. In addition, the TLR 4 signalling pathway seems to be triggered to a greater extent by higher PCL and HA concentrations, but the alignment of the fibers prevents the triggering of this receptor. Taken together, TLR reporter cells were shown to be a useful and effective tool to study the potential of scaffolds to induce immune responses and the results obtained can be used to inform the design of fibrous scaffolds for tendon repair.

Preparation and characterization of amphiphilic, biodegradable, waterborne polyurethanes without using organic solvent and catalyst.

Traditionally, waterborne polyurethanes (WPUs) are prepared using toxic organic solvents and catalysts. These WPUs are non-biodegradable and are buried or incinerated after the expiration date. This has adverse effects on the environment and human health, which limits the applications of WPUs. Herein, a special synthetic method was developed for biodegradable waterborne polyurethane (BWPU) by adding hydrophilic prepolymers into WPU prepolymers without using organic solvents and catalysts. Different proportions of polyethylene glycol (PEG) were introduced into polycaprolactone (PCL)-based BWPUs to improve the comprehensive properties. Results showed that as the PEG content was increased from 0 to 16 wt%, the solid content of BWPU increased from 34.8 wt% to 53.1 wt%, while the tensile strength and Young's modulus of BWPU films increased from 21.81 MPa to 56.83 MPa and 8.08 MPa to 19.4 MPa, respectively. However, the elongation at break did not decrease significantly, but still reached 827.17%. With an increase in PEG content, the crystallinity and phase separation decreased, while the hydrophilicity and surface energy increased for BWPU films. In addition, the prepared BWPUs had good biodegradability in PBS/lipase solution. The mass loss of BWPU without PEG reached 6.3 wt% after 4 weeks of degradation, whereas the mass losses of BWPUs with PEG reached 2.3-4.3 wt%. Obviously, the introduction of PEG did not increase biodegradability. Thus, the higher the PCL content, the faster the biodegradation rate. This work would provide an effective method for the preparation of ecofriendly biodegradable BWPU with excellent comprehensive properties.

Fabrication and biocompatibility evaluation of hydroxyapatite-polycaprolactone-gelatin composite nanofibers as a bone scaffold.

One approach to addressing bone defects involves the field of bone tissue engineering, with scaffolds playing an important role. The properties of the scaffold must be similar to those of natural bone, including pore size, porosity, interconnectivity, mechanical attributes, degradation rate, non-toxicity, non-immunogenicity, and biocompatibility. The primary goals of this study are as follows: first, to evaluate hydroxyapatite (HA)/polycaprolactone (PCL)/gelatin nanofiber scaffolds based on functional groups, fibre diameter, porosity, and degradation rate; second, to investigate the interaction between HA/PCL/gelatin scaffolds and osteoblast cells (specifically, the ATCC 7F2 cell line) using in vitro assays, including cell viability and adhesion levels. The fibre samples were fabricated using an electrospinning technique with a 15 kV voltage, a spinneret-collector distance of 10 cm, and a flow rate of 0.3 mL hour-1. The process was applied to five different HA/PCL/gelatin concentration ratios: 50 : 40 : 10; 50 : 30 : 20; 50 : 25 : 25; 50 : 20 : 30; 50 : 35 : 15 (in %wt). Fourier Transform Infrared (FTIR) spectrum analysis and tests revealed no differences in functional groups across the five compositions. The identified functional groups include PO4 3-, OH-, CO3 2- and C[double bond, length as m-dash]O stretching. Notably, an increase in PCL concentrations resulted in larger fiber diameters, ranging from 369-1403 nm with an average value of 929 ± 175 nm. The highest porosity percentage was (77.27 ± 11.57) %, and a sufficient degradation rate of up to 3.5 months facilitated the proliferation process of osteoblast cells. Tensile strength assessments revealed a significant increase in tensile strength with the addition of PCL, reaching a peak of 1.93 MPa. The MTT assay demonstrated a discernible increase in cell proliferation, as evidenced by increased cell viability percentages on days 1, 3, and 5. Concurrently, the fluorescence microscopy examination indicated an increase in cell numbers, which was especially noticeable on days 1 and 5. The SEM analysis confirmed the biocompatibility of the HA/PCL/gelatin nanofiber scaffold, as osteoblast cells attached and dispersed successfully five days after seeding. Based on these findings, the HA/PCL/gelatin nanofiber scaffold emerges as a very promising candidate for treating bone damage.

Investigation on Electrospun and Solvent-Casted PCL-PLGA Blends Scaffolds Embedded with Induced Pluripotent Stem Cells for Tissue Engineering.

The design, production, and characterisation of tissue-engineered scaffolds made of polylactic-co-glycolic acid (PLGA), polycaprolactone (PCL) and their blends obtained through electrospinning (ES) or solvent casting/particulate leaching (SC) manufacturing techniques are presented here. The polymer blend composition was chosen to always obtain a prevalence of one of the two polymers, in order to investigate the contribution of the less concentrated polymer on the scaffolds' properties. Physical-chemical characterization of ES scaffolds demonstrated that tailoring of fibre diameter and Young modulus (YM) was possible by controlling PCL concentration in PLGA-based blends, increasing the fibre diameter from 0.6 to 1.0 µm and reducing the YM from about 22 to 9 MPa. SC scaffolds showed a "bubble-like" topography, caused by the porogen spherical particles, which is responsible for decreasing the contact angles from about 110° in ES scaffolds to about 74° in SC specimens. Nevertheless, due to phase separation within the blend, solvent-casted samples displayed less reproducible properties. Furthermore, ES samples were characterised by 10-fold higher water uptake than SC scaffolds. The scaffolds suitability as iPSCs culturing support was evaluated using XTT assay, and pluripotency and integrin gene expression were investigated using RT-PCR and RT-qPCR. Thanks to their higher wettability and appropriate YM, SC scaffolds seemed to be superior in ensuring high cell viability over 5 days, whereas the ability to maintain iPSCs pluripotency status was found to be similar for ES and SC scaffolds.

The influence of polycaprolactone content on the surface properties of polyurethane networks

AbstractThe aim of this work was to examine the influence of polycaprolactone (PCL) as a soft segment (SS) on the surface properties of polyurethane networks (PUNs). Five PUNs with different SS content (from 10 to 50 wt%) were prepared using Boltorn® aliphatic hyperbranched polyester of the second pseudo generation and isophorone diisocyanate as components of hard segments. The structure, hydrophobicity, wettability, and swelling behavior of these PUNs were investigated. Primarily, the obtained results showed that properties of prepared PUNs strongly depend on the content of SS that is, PCL. It has been established that the increase of SS content reduced the degree of hydrogen bonding in PUNs. Also, the increase of the SS content in PUNs induced appearance of more pronounced microphase separated morphology, better hydrophobicity and non‐wetting with diiodomethane. Simultaneously, the increase of the SS content led to the decrease of contact angles with formamide, and surface free energy of the prepared PUNs. These PUNs show good surface properties that are required for their potential application such as coatings.

A Study of the Relationship between Polymer Solution Entanglement and Electrospun PCL Fiber Mechanics.

Electrospun fibers range in size from nanometers to micrometers and have a multitude of potential applications that depend upon their morphology and mechanics. In this paper, we investigate the effect of polymer solution entanglement on the mechanical properties of individual electrospun polycaprolactone (PCL) fibers. Multiple concentrations of PCL, a biocompatible polymer, were dissolved in a minimum toxicity solvent composed of acetic acid and formic acid. The number of entanglements per polymer (ne) in solution was calculated using the polymer volume fraction, and the resultant electrospun fiber morphology and mechanics were measured. Consistent electrospinning of smooth fibers was achieved for solutions with ne ranging from 3.8 to 4.9, and the corresponding concentration of 13 g/dL to 17 g/dL PCL. The initial modulus of the resultant fibers did not depend upon polymer entanglement. However, the examination of fiber mechanics at higher strains, performed via lateral force atomic force microscopy (AFM), revealed differences among the fibers formed at various concentrations. Average fiber extensibility increased by 35% as the polymer entanglement number increased from a 3.8 ne solution to a 4.9 ne solution. All PCL fibers displayed strain-hardening behavior. On average, the stress increased with strain to the second power. Therefore, the larger extensibilities at higher ne also led to a more than double increase in fiber strength. Our results support the role of polymer entanglement in the mechanical properties of electrospun fiber at large strains.

Healable and recyclable multiblock polyurethanes with mechanical performance Tailorability based on hierarchical phase separation and dynamic bond interaction

Thermoplastic polyurethanes (TPUs) have been demonstrated high versatility in widespread applications. In view of today's sustainable society, the advanced TPUs which combine both excellent mechanical properties and functionalities such as the self-healing and recyclability can extend utilization scope and service life. Herein, we reported a multiblock polyurethane with outstanding mechanical performance, self-healing capability and recyclability based on strong microphase-separated biocompatible polycaprolactone (PCL) semicrystalline segments and ultra-highly flexible polydimethylsiloxane (PDMS) segments. The mechanical performance of the designed PUs can be tuned from resilient elastomer to shape memory plastics by varying the molecular parameter of segments, and the fast self-healing was achieved through the synergetic effects of dynamic disulfide bond and hydrogen bonding interaction. The PUs with high PCL contents exhibit high tensile strength and high toughness (high up to 45 MPa, 511 MJ m−3, respectively) after thermal treatment and show shape memory effects, while these with high PDMS contents perform as ligament elastomer. We demonstrated the principles of high mechanical performance in the phase-separated multiblock PU, in which the hierarchical nanostructures including the microphase separation between PDMS and PCL blocks, the nanophase segregation of the carbamate segments as well as the semi-crystalline behavior of PCL segments endow these healable and recyclable PUs with high strength, high stretchability and high toughness. This work demonstrated tremendous potentials of utilizing strong microphase separated segments and dynamic bond chain extenders to design functional thermoplastic PU materials.

Synthesis and characterization of chitosan/collagen/polycaprolactone hydrogel films with enhanced biocompatibility and hydrophilicity for artificial tendon applications

Regenerative medicine confronts various obstacles, such as creating and advancing biomaterials. Besides being safe, such materials should promote cellular activity. Polycaprolactone (PCL) has numerous medical applications as an engineering material. However, these polymers lack hydrophilicity. Herein, chitosan (CS)/collagen (COL)/polycaprolactone hydrogel films (CSCPs) were synthesized with different weight ratios of PCL; specifically, CS/COL (CSC): PCL content of 1:3, 1:6, and 1:9. For this purpose, novel COL immobilization on CS was performed via covalent attachment. Following the addition of PCL to CSC hydrogel, the resulting CSCP hydrogel films were characterized using tensile measurements, TGA, XRD, FTIR, and FE-SEM. A greater PCL content increases the elongation at break from 134.8 to 369.5 % and the tensile strength of the hydrogel films from 4.8 to 18.4 MPa. The hydrophobicity of prepared specimens was assessed through water absorption and contact-angle tests. For CSCP3 to CSCP9, the water contact angle increased from 61.03° to 70.82°. After 48 days, CSCP6 and CSCP9 hydrogel films demonstrated a slow rate of degradation, losing <15 % of their weight. Moreover, all three types of hydrogel films exhibited high biocompatibility (higher than 95 % after three days), as confirmed by the MTT assay. The hemolysis rates of CSCP hydrogel films were <2 %, which could be deemed safe for contact with a blood environment. The presence of no costly and bio-based crosslinking agents and desired characteristics for tissue engineering applications suggest that CSCP hydrogel films may be promising candidates for use in artificial tendons.

Controllable synthesis of anisotropic liquid metal-polycaprolactone composites with high viscosity and superior degradability

Composite materials hold great promise in wearable implant devices, self-healing materials, and electromagnetic shielding materials, due to the merits of flexibility, impact resistance, and low cost. Herein, a novel, conductive, anisotropic, and environmentally degradable liquid metal-polycaprolactone composite material was controllably prepared for the carrier of electronic devices, using polycaprolactone (PCL) polymer as the base, liquid metal (LM) particles with diameters of 400–500 µm as the functional droplet. By regulating the composition and ratio of LM and PCL, three composite materials were successfully obtained: LM-PCL (10 wt%)− 1, LM-PCL (20 wt%)− 2, and LM-PCL (40 wt%)− 3. However, among the above three materials, only LM-PCL-1 was found to be an anisotropic material with conductivity on one side and insulation on the other. Many stretchable fibers could be prepared by cooling and extruding LM-PCL-1 in water. Besides, the more PCL content in LM-PCL, the higher the hardness. Finally, the degradation effects of LM-PCL in acid, alkali, and neutral aqueous solutions were systematically investigated. The degradation rate of LM-PCL was the fastest in the concentration of 10 mol/L HCL. LM in the composite material could be recycled by centrifugation. The prepared LM-PCL composites could be widely used in microelectronics and sensor parts.

A facile strategy for fine-tuning the drug release efficacy of poly-L-lactic acid-polycaprolactone coatings by liquid flame spray

The diversity of medical application scenarios demands fine-tuning of drug release profiles for better patient care. Here we report a facile strategy to construct composite coatings as universal drug delivery systems with tunable release efficacy. A poly-L-lactic acid (PLLA)-polycaprolactone (PCL) coating was fabricated by liquid flame spray and its performance was verified by loading chloramphenicol (CAM) as bactericidal component. Physiochemical analyses revealed the homogeneity of chemistry and integrity of functional groups of the composite coatings. Release of CAM was enhanced by the increase of the PCL content in the composite coatings, showing a controllable manner. Kinetics analysis suggested the release mechanism of Korsmeyer-Peppas model for both the PLLA-CAM and the PCL-CAM coatings, and the release regime for the PLLA-PCL composite coatings transited from the Higuchi model to the Korsmeyer-Peppas model when the PCL content increased from 30 % to 70 %. Further antibacterial testing revealed tailorable antibacterial activity of the coatings against both Escherichia coli and Staphylococcus aureus. Regulating the release of the drug CAM through altering PCL content in the PLLA-PCL coating would give inspiring insight into green fabrication of polymeric coatings with tunable drug release for versatile applications.

In-situ synthesis of MAPbBr3 perovskite quantum dot-polycaprolactone composites with enhanced photoluminescence quantum yield and stability

Polymer encapsulation is regarded as an efficient strategy to enhance the stability of perovskite quantum dots (PQDs), and also endows the perovskites with advantages in mechanical properties and processibility. In this work, polymer encapsulation was achieved by in-situ synthesis of PQDs in polycaprolactone (PCL) polymer, which avoiding time-consuming process of blending polymer with PQDs. Moreover, besides of acting as encapsulation matrix, PCL in toluene could provide large nucleation sites for PQDs formation, resulting in the relatively smaller PQDs size and enhanced photoluminescence quantum yield (PLQY) with respect to the composites prepared by physical blending. Profiting from PCL encapsulation, the as-synthesized PQDs-PCL composites exhibited enhanced stability against UV light, water and heat. The strong interaction between PQDs and PCL in composites with high PCL concentration could endow them with more significantly improved PL stability under UV-light illumination and relatively better mechanical properties compared to the composites with high PQDs concentration. This work provides an efficient method to synthesize PQDs-polymer composites with enhanced PLQY and stability, which would promote practical applications of PQDs materials in the optoelectronic applications.

Electrosprayed low toxicity polycaprolactone microspheres from low concentration solutions

Abstract This work describes the successful tunable production of polycaprolactone (PCL) microspheres using very low-concentration solutions. The PCL solutions (1, 3, and 5 w/v%) were prepared with different solvents (dichloromethane (DCM) and chloroform (CHL)) and electrosprayed at different distances (5, 10, and 15 cm). The solubility and viscosity of PCL solutions were in accordance with the polymer concentrations, demonstrating PCL-DCM gave a higher solubility of PCL, but PCL-CHL solutions had a higher viscosity. Optical microscopy (OM) and field emission-scanning electron microscopy (FE-SEM) revealed that the PCL-DCM preparations produced a smaller and more uniform microsphere size and pore size compared to PCL-CHL microspheres. The linear regression analysis showed that the solubility and viscosity of PCL concentration influence the size of microspheres more greatly than the pore size. The toxicity results indicated that PCL-CHL and PCL-DCM are well-tolerated by zebrafish embryos that were able to follow a normal growth pathway and can thus be deemed safe.

Fabrication of 3D Printed Polylactic Acid/Polycaprolactone Nanocomposites with Favorable Thermo-Responsive Cyclic Shape Memory Effects, and Crystallization and Mechanical Properties

In this work, 3D printed polylactic acid (PLA)/polycaprolactone (PCL) nanocomposites with favorable thermo-responsive cyclic shape memory effects (SMEs) and crystallization and mechanical properties were fabricated using a two-step method. First, an isocyanate-terminated PCL diol (PCL-NCO) was synthesized through the reaction between isocyanate groups of hexamethylene diisocyanate and active hydroxyl groups of PCL diol, and its physicochemical properties were characterized. A PLA/PCL blend with a PCL content of 50 wt% was fabricated via fused filament fabrication (FFF) 3D printing, and the influence of the PCL-NCO on the SME of the PLA/PCL blend was studied. The results indicated that the PCL-NCO significantly improved the cyclic shape memory performance of 3D printed PLA/PCL blends and was proved to be an effective interface compatibilizer for the blend system. Subsequently, the structure and properties of 3D printed PLA/PCL nanocomposites were investigated in detail by adding cellulose nanocrystal-organic montmorillonite (CNC-OMMT) hybrid nanofillers with different contents. It was found that the hybrid nanofillers greatly enhanced crystallization and mechanical properties of the nanocomposites due to adequate dispersion. The modification of the PLA/PCL blend and the preparation of the 3D printed nanocomposite can not only prolong the service life of a shape memory polymer product, but also broaden its application scope in advanced fields.