Polycaprolactone Films Research Articles

Bioresorbable films of polycaprolactone blended with poly(lactic acid) or poly(lactic-co-glycolic acid)

Recent complications on the use of polypropylene meshes for hernia repair has led to the development of meshes or films, which were based on resorbable polymers such as polycaprolactone (PCL), polylactic acid (PLA) and poly(lactic-co-glycolic acid) (PLGA). These materials are able to create suitable bioactive environment for the growth and development of cells. In this research, we mainly focused on the relations among structure, mechanical performance and biocompatiblity of PCL/PLA and PCL/PLGA and blends prepared by solution casting. The films were characterized regarding the chemical structure, morphology, physicochemical properties, cytotoxicity, biocompatibility and cell growth. All the films showed high tensile strength ranging from 9.5 to 11.8 MPa. SAXS showed that the lamellar stack structure typical for PCL was present even in the blend films while the morphological parameters of the stacks varied slightly with the content of PLGA or PLA in the blends. WAXS indicated preferential orientation of crystallites (and thus, also the lamellar stacks) in the blend films. In vitro studies revealed that PCL/PLGA films displayed better cell adhesion, spreading and proliferation than PCL/PLA and PCL films. Further the effect of blending on the degradation was investigated, to understand the significant variable within the process that could provide further control of cell adhesion. The results showed that the investigated blend films are promising materials for biomedical applications.

Bioactive and Biodegradable Polycaprolactone-Based Nanocomposite for Bone Repair Applications.

This study investigated the relationship between the structure and mechanical properties of polycaprolactone (PCL) nanocomposites reinforced with baghdadite, a newly introduced bioactive agent. The baghdadite nanoparticles were synthesised using the sol-gel method and incorporated into PCL films using the solvent casting technique. The results showed that adding baghdadite to PCL improved the nanocomposites' tensile strength and elastic modulus, consistent with the results obtained from the prediction models of mechanical properties. The tensile strength increased from 16 to 21 MPa, and the elastic modulus enhanced from 149 to 194 MPa with fillers compared to test specimens without fillers. The thermal properties of the nanocomposites were also improved, with the degradation temperature increasing from 388 °C to 402 °C when 10% baghdadite was added to PCL. Furthermore, it was found that the nanocomposites containing baghdadite showed an apatite-like layer on their surfaces when exposed to simulated body solution (SBF) for 28 days, especially in the film containing 20% nanoparticles (PB20), which exhibited higher apatite density. The addition of baghdadite nanoparticles into pure PCL also improved the viability of MG63 cells, increasing the viability percentage on day five from 103 in PCL to 136 in PB20. Additionally, PB20 showed a favourable degradation rate in PBS solution, increasing mass loss from 2.63 to 4.08 per cent over four weeks. Overall, this study provides valuable insights into the structure-property relationships of biodegradable-bioactive nanocomposites, particularly those reinforced with new bioactive agents.

Development of poly(ℇ‐caprolactone)‐based composite packaging films incorporated nanofillers for enhanced strawberry quality

AbstractThe aim of the present study was to develop a packaging material for strawberry fruit by incorporating nanofiller such as graphene oxide (GO), graphene oxide modified with silane coupling agent (fGO), and titanium dioxide (TiO2) into a polycaprolactone (PCL) matrix using the solution casting method. In the first stage, graphene oxide was synthesized from graphite by the modified Hummers' method. Subsequently, the synthesized GO was modified with the silane coupling agent. PCL film, PCL/GO, PCL/fGO, PCL/GO/TiO2, and PCL/fGO/TiO2 nanocomposite films were eventually developed. The prepared films were characterized by structural, chemical, and thermal analysis by AFM, FTIR, XRD, DSC, TGA, water contact angle analysis and food packaging test. Structural and chemical analyses revealed that the synthesis and modification processes of GO were successfully achieved. The roughness values of the PCL/fGO and PCL/fGO/TiO2 films were found as 34.1 ± 1.2 nm and 43.3 ± 2.7 nm, respectively, which displayed a relatively smooth surface morphology compared to other films. The contact angle value for the PCL/fGO and PCL/fGO/TiO2 films sightly increased from 79.83° to 80.34°, respectively, with the addition of TiO2 to the matrix. The addition of GO into the polymer matrix increased the water absorption value of the PCL film to the maximum value of 19.64%; however, the addition of TiO2 nanoparticles decreased the water absorption value of the films by 14.62%. The results of the packaging test of strawberry fruit for 21 days demonstrated that the PCL/fGO/TiO2 nanocomposite film had the potential to be used as a food packaging film due to its ability to protect the freshness of strawberries.

Polycaprolactone—Eugenol systems: Interactions, retention and diffusion of the bioactive compound

AbstractThe retention ability of polycaprolactone (PCL) films and their potential use for applications that require controlled release, were evaluated using eugenol, an aroma compound as a model active substance. The PCL‐eugenol samples were prepared by means of a low‐temperature extrusion process that resulted in minimum losses of eugenol and a final proportion close to nominal content. The release kinetics of eugenol were monitored for different conditions of temperature and relative humidity, both by an usual gas chromatography analysis but also by spectroscopy method that revealed sufficient. The release kinetics were compared to the numerical results obtained by the resolution of Fickian and a power‐law models. Results showed that the temperature had an influence on the release rate, and that the release kinetics were mostly Fickian. Moreover, the determination of the Arrhenius parameters will allow the use of the Fickian model to dimension PCL samples for other applications requiring controlled release.

Wood Cellulose Nanofibers Grafted with Poly(ε-caprolactone) Catalyzed by ZnEu-MOF for Functionalization and Surface Modification of PCL Films.

Renewable cellulose nanofiber (CNF)-reinforced biodegradable polymers (such as polycaprolactone (PCL)) are used in agriculture, food packaging, and sustained drug release. However, the interfacial incompatibility between hydrophilic CNFs and hydrophobic PCL has limited further application as high-performance biomaterials. In this work, using a novel ZnEu-MOF as the catalyst, graft copolymers (GCL) with CNFs were grafted with poly(ε-caprolactone) (ε-CL) via homogeneous ring-opening polymerization (ROP), and used as strengthening/toughening nanofillers for PCL to fabricate light composite films (LCFs). The results showed that the ZnEu-MOF ([ZnEu(L)2(HL)(H2O)0.39(CH3OH)0.61]·H2O, H2L is 5-(1H-imidazol-1-yl)-1,3-benzenedicarboxylic acids) was an efficient catalyst, with low toxicity, good stability, and fluorescence emissions, and the GCL could efficiently promote the dispersion of CNFs and improve the compatibility of the CNFs and PCL. Due to the synergistic effect of the ZnEu-MOF and CNFs, considerable improvements in the mechanical properties and high-intensity fluorescence were obtained in the LCFs. The 4 wt% GCL provided the LCF with the highest strength and elastic modulus, which increased by 247.75% and 109.94% compared to CNF/PCL, respectively, showing the best elongation at break of 917%, which was 33-fold higher than CNF/PCL. Therefore, the ZnEu-MOF represented a novel bifunctional material for ROP reactions and offered a promising modification strategy for preparing high-performance polymer composites for agriculture and biomedical applications.

Physical and biological changes of copper oxide and hydroxyapatite filled in polycaprolactone scaffolds: Cellular growth behavior and antibacterial activity

Burns have placed a devastating burden on public health because of leading to an increased risk of infection. Therefore, the development of an effective antibacterial dressing for wound healing is essential. The present work is mainly based on the fabrication of biodegradable polycaprolactone (PCL) films through a simple and cheap process of polymer casting using a novel combination of hydroxyapatite (HAP), cuprous oxide (Cu2O) NPs and graphene oxide (GO) nanosheets which have a great effect in preventing colonization and to modify the wound dreasing. The compositions played a key role in decreasing the contact angle of PCL from 47.02° to 11.53°. Further, the cell viability exhibited a viable cell ratio of 81.2% after 3 days of culturing. Moreover, the highest antibacterial activity was obtained from the film of Cu2O@PCl and showed high impact results in antibacterial behavior.

Biodegradable layered double hydroxide based polymeric films for sustainable food packaging applications

In this study, solution casting was used to create hybrid biodegradable films that were made of Polycaprolactone (PCL) and Zn-Al layered double hydroxide (LDH) intercalated with salicylate (SA) (P-L-S nanocomposites). P-L-S (5%) nanocomposite film has a water vapor transmission rate of just 212.5 g/m2/day at 85% relative humidity, which is 55.5% less than that of pure PCL film. This outstanding performance of the water vapor barrier is mostly due to the convoluted action of 2D LDH nanohybrids. In addition, the hydroxyl groups of LDH create hydrogen bonds with the entering water molecules, further preventing the passage of water vapor. The aforementioned nanocomposite showed excellent biodegradability by decomposing by over 75% in just 90 days. More than 94% inhibition of E. coli and S. aureus in 30 min, which is a promising finding when compared to the existing literature, was demonstrated as a result of a controlled release of salicylate (intercalated between the inorganic lamella) to the medium. The P-L-S (5%) nanocomposite additionally showed the best radical scavenging ability against DPPH. (82%) in only 72 h. The aforementioned characteristics point to the possible uses for P-L-S nanocomposite films in the domain of biodegradable packaging.

Monitoring Cell Adhesion on Polycaprolactone-Chitosan Films with Varying Blend Ratios by Quartz Crystal Microbalance with Dissipation.

A detailed understanding of the cell adhesion on polymeric surfaces is required to improve the performance of biomaterials. Quartz crystal microbalance with dissipation (QCM-D) as a surface-sensitive technique has the advantage of label-free and real-time monitoring of the cell-polymer interface, providing distinct signal patterns for cell-polymer interactions. In this study, QCM-D was used to monitor human fetal osteoblastic (hFOB) cell adhesion onto polycaprolactone (PCL) and chitosan (CH) homopolymer films as well as their blend films (75:25 and 25:75). Complementary cell culture assays were performed to verify the findings of QCM-D. The thin polymer films were successfully prepared by spin-coating, and relevant properties, i.e., surface morphology, ζ-potential, wettability, film swelling, and fibrinogen adsorption, were characterized. The adsorbed amount of fibrinogen decreased with an increasing percentage of chitosan in the films, which predominantly showed an inverse correlation with surface hydrophilicity. Similarly, the initial cell sedimentation after 1 h resulted in lesser cell deposition as the chitosan ratio increased in the film. Furthermore, the QCM-D signal patterns, which were measured on the homopolymer and blend films during the first 18 h of cell adhesion, also showed an influence of the different interfacial properties. Cells fully spread on pure PCL films and had elongated morphologies as monitored by fluorescence microscopy and scanning electron microscopy (SEM). Corresponding QCM-D signals showed the highest frequency drop and the highest dissipation. Blend films supported cell adhesion but with lower dissipation values than for the PCL film. This could be the result of a higher rigidity of the cell-blend interface because the cells do not pass to the next stages of spreading after secretion of their extracellular matrix (ECM) proteins. Variations in the QCM-D data, which were obtained at the blend films, could be attributed to differences in the morphology of the films. Pure chitosan films showed limited cell adhesion accompanied by low frequency drop and low dissipation.

Preparation of covalent organic framework-based nanofibrous films with temperature-responsive release of thymol for active food packaging

Thymol (THY) is commonly used in active food packaging, however because of its high volatility, poor water solubility, and strong aromatic odor, the application of THY is facing challenges. Herein, covalent organic frameworks (COFs) were synthesized in room temperature by asymmetric monomer exchange method for THY encapsulation, and solution blow spinning was used to fabricate the THY@COF/polycaprolactone (PCL) nanofibrous films. The synthesized COFs had a large specific surface area, porous structure, and loading capacity of 30.35% for THY, and THY@COFs possessed good thermal stability. Characterization analysis showed that THY@COFs were successfully incorporated into the PCL films and increased the barrier property of the films. Besides, the films showed good biocompatibility and antibacterial activity. Moreover, THY@COF/PCL films exhibited temperature-responsive THY release profiles, which is important for practical preservation applications, especially for preserving food in warm environments. Overall, THY@COF/PCL films possess promising potential in active food packaging.

Promising nanocomposites for food packaging based on cellulose – PCL films reinforced by using ZnO nanoparticles in an ionic liquid

The fact that most composites consist of polluting synthetic materials has prompted a search for biodegradable replacements based on cellulose fibers and polycaprolactone as potential packaging materials. In this work, we developed a green, efficient approach to rendering hydrophobic polycaprolactone (PCL) compatible with hydrophilic cellulose fibers by using an ionic liquid as a nanowelding agent in the presence of zinc oxide nanoparticles (ZnONPs). Transparent biobased nanocomposite films were thus directly obtained by in situ ring-opening polymerization (ROP) of ε-caprolactone (CL) monomers onto the dissolved cellulose matrix by using the ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac). [EMIM]Ac and ZnONPs were efficiently catalyzed ε-caprolactone ROP under mild conditions. Cellulose-grafted PCL nanocomposite films were obtained by adding variable amounts of CL and ZnONPs to the cellulose matrix. The maximum grafting of 40% was achieved by using 5▒wt% ZnONPs and 70% CL. FTIR spectra confirmed the presence of PCL in the nanocomposites. Also, FE-SEM revealed uniform dispersion of ZnONPs and PCL in the regenerated cellulose matrix, and trapping of nanoparticles in nanofibrils after the cellulose matrix was regenerated. X-ray diffraction (XRD) spectra showed a decreased apparent crystallinity and crystallite size. The XRD results also confirmed that the crystal properties of the nanocomposite films and an all-cellulose composite (ACC) were almost identical. The mechanical, barrier and optical properties of the nanocomposite films were significantly better than those of the ACC film by effect of the incorporation of ZnONPs and PCL especially with 5▒wt% ZnONPs and 70% CL). The nanocomposite films exhibited acceptable antioxidant activity and UV-light barrier properties, so they hold promise for used in food packaging. Nanocomposite films are in fact multifunctional materials with the potential for use in cellulose-based food packaging by virtue of their being transparent and bio-based, and possessing very good water vapor and oxygen barrier properties.

In Situ Compatibilized Blends of PLA/PCL/CAB Melt-Blown Films with High Elongation: Investigation of Miscibility, Morphology, Crystallinity and Modelling.

Ternary-blended, melt-blown films of polylactide (PLA), polycaprolactone (PCL) and cellulose acetate butyrate (CAB) were prepared from preliminary miscibility data using a rapid screening method and optical ternary phase diagram (presented as clear, translucent, and opaque regions) as a guide for the composition selection. The compositions that provided optically clear regions were selected for melt blending. The ternary (PLA/PCL/CAB) blends were first melt-extruded and then melt-blown to form films and characterized for their tensile properties, tensile fractured-surface morphology, miscibility, crystallinity, molecular weight and chemical structure. The results showed that the tensile elongation at the break (%elongation) of the ternary-blended, melt-blown films (85/5/10, 75/10/15, 60/15/25 of PLA/PCL/CAB) was substantially higher (>350%) than pure PLA (ca. 20%). The range of compositions in which a significant increase in %elongation was observed at 55−85% w/w PLA, 5−20% w/w PCL and 10−25% w/w CAB. Films with high %elongation all showed good interfacial interactions between the dispersed phase (PCL and CAB) and matrix (PLA) in FE-SEM and showed improvements in miscibility (higher intermolecular interaction and mixing) and a decrease in the glass transition temperature, when compared to the low %elongation films. The decrease in Mw and Mn and the formation of the new NMR peaks (1H NMR at 3.68−3.73 ppm and 13C NMR at 58.54 ppm) were observed in only the high %elongation films. These are expected to be in situ compatibilizers that are generated during the melt processing, mostly by chain scission. In addition, mathematical modelling was used to study the optimal ratio and cost-effectiveness of blends with optimised mechanical properties. These ternary-blended, melt-blown films have the potential for use in both packaging and medical devices with excellent mechanical performance as well as inherent economic and environmental capabilities.

Fabrication of Nanostructured Polycaprolactone (PCL) Film Using a Thermal Imprinting Technique and Assessment of Antibacterial Function for Its Application.

In the use of the medical devices, it is essential to prevent the attachment of bacteria to the device surface or to kill the attached bacteria. To kill bacteria, many researchers have used antibiotics or studied nanostructure-based antibacterial surfaces, which rely on mechanical antibacterial methods. Several polymers are widely used for device fabrication, one of which is polycaprolactone (PCL). PCL is biocompatible, biodegradable, easy to fabricate using 3D printing, relatively inexpensive and its quality is easily controlled; therefore, there are various approaches to its use in bio-applications. In addition, it is an FDA-approved material, so it is often used as an implantable material in the human body. However, PCL has no inherent antibacterial function, so it is necessary to develop antibacterial functions in scaffold or film-based PCL medical devices. In this study, process parameters for nanopillar fabrication were established through a simple thermal imprinting method with PCL. Finally, a PCL film with a flexible and transparent nanopillar structure was produced, and the mechano-bactericidal potential was demonstrated using only one PCL material. PCL with nanopillars showed bactericidal ability against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) bacteria cultured on its surface that resulted in membrane damage and death due to contact with nanopillars. Additionally, bacteriostatic results were shown to inhibit bacterial growth and activity of Staphylococcus aureus (S. aureus) on PCL nanostructured columns. The fabricated nanopillar structure has confirmed that mechanically induced antibacterial function and can be applied to implantable medical devices.

Tuning polycaprolactone degradation for long acting implantables

Polycaprolactone (PCL) is a bioresorbable polyester that has been widely used in biomedical applications since the 1970s. Because PCL undergoes bulk degradation, it is especially amenable to drug delivery applications. To ensure safety, a drug eluting implant must typically remain intact until the drug is exhausted, and following exhaustion the implant should breakdown and be resorbed. Many PCL based implants target delivery on the order of six months to one year, yet the time to degradation of PCLs is often on the order of multiple years. It is known that the time to degradation of PCL is directly related to its initial molecular weight; however, the limited integrity of neat low molecular weight PCLs make them unsuitable for implantation. Here we outline an approach to tune the time to degradation of PCL by blending low and high molecular weight polymers. We show that the degradation rate and permeability of PCL films are insensitive to their composition, and weight-average molecular weight (Mw) is predictive of time to fragmentation. Additionally, we demonstrate that compositions with up to 50 wt % low molecular weight polymer can retain the mechanical properties of a high molecular weight material. The resulting material has a lower effective Mw and a shorter time to degradation. In accelerated testing, it is possible to reduce time to degradation by roughly two-fold without sacrificing mechanical integrity. This provides versatility in adapting device designs to meet the needs of a specific application. These findings have implications in the development of biodegradable drug eluting implants, tissue engineering scaffolds, and resorbable surgical materials.

Effect of Functionalization of the Polycaprolactone Film Surface on the Mechanical and Biological Properties of the Film Itself.

The lack of suitable functional groups for cell adhesion on the surface of Polycaprolactone (PCL) is one of the main limitations in order to use PCL for biomedical applications. The aim of this research is to modify the PCL film surface using arginine, via an aminolysis reaction. In this regard, after PCL films formation by casting method, they were immersed in arginine solutions of various concentration at room temperature or then heated to 40 °C and in the presence of isopropanol or without it. To assess the structure of the modified surface, its wettability, and mechanical properties, methods of measuring the contact angle and the strip tensile test were used, and to compare the degree of attachment and the rate of cell proliferation, the method of fluorescent staining of cultured cells was used. The change in protein synthesis by cells on the modified surface was assessed using Western blotting. The results obtained show that the treatment of PCL films with an aqueous solution of arginine at room temperature for 1 day increases the hydrophilicity of the surface. Wherein surface modification led to a two-fold decrease of mechanical strength and flow stress, but elongation increase by about 30% for PCL films after modification in 0.5 M aqueous arginine solution at room temperature. Moreover, cell attachment and proliferation, as well as collagen synthesis, were significantly enhanced after arginine modification. The proposed simple and effective method for modifying PCL films with arginine significantly expands the possibilities for developing biocompatible scaffolds for tissue engineering.

Assessing the response of human primary macrophages to defined fibrous architectures fabricated by melt electrowriting.

The dual role of macrophages in the healing process depends on macrophage ability to polarize into phenotypes that can propagate inflammation or exert anti-inflammatory and tissue-remodeling functions. Controlling scaffold geometry has been proposed as a strategy to influence macrophage behavior and favor the positive host response to implants. Here, we fabricated Polycaprolactone (PCL) scaffolds by Melt Electrowriting (MEW) to investigate the ability of scaffold architecture to modulate macrophage polarization.Primary human macrophages unpolarized (M0) or polarized into M1, M2a, and M2c phenotypes were cultured on PCL films and MEW scaffolds with pore geometries (square, triangle, and rhombus grid) characterized by different angles.M0, M2a, and M2c macrophages wrapped along the fibers, while M1 macrophages formed clusters with rounded cells. Cell bridges were formed only for angles up to 90°. No relevant differences were found among PCL films and 3D scaffolds in terms of surface markers. CD206 and CD163 were highly expressed by M2a and M2c macrophages, with M2a macrophages presenting also high levels of CD86. M1 macrophages expressed moderate levels of all markers. The rhombus architecture promoted an increased release by M2a macrophages of IL10, IL13, and sCD163 compared to PCL films. The proangiogenic factor IL18 was also upregulated by the rhombus configuration in M0 and M2a macrophages compared to PCL films.The interesting findings obtained for the rhombus architecture represent a starting point for the design of scaffolds able to modulate macrophage phenotype, prompting investigations addressed to verify their ability to facilitate the healing process in vivo.

Membrane supported poly(butylene adipate-co-terephthalate) nanofibrous matrices as cardiac patch: Effect of basement membrane for the fiber deposition and cellular behavior

Electrospun nanofibrous matrices are convenient biomaterials that mimic extracellular matrices for adhesion, migration, proliferation, and differentiation of cells. The aim of this study is to optimize the electrospinning parameters for poly(butylene adipate-co-terephthalate) (PBAT) nanofiber production by the response surface methodology (RSM) and to develop a suitable material design for the usability of PBAT in cardiac tissue engineering. Therefore, electrospun PBAT nanofibrous matrices collected on solvent-casted polycaprolactone (PCL) or PBAT basement membranes at optimized conditions. The attachment and proliferation behavior of the H9C2 rat cardiomyoblasts investigated on different PBAT and PCL surface features as a model cell line. For this purpose, neat PBAT and PCL films have been used comparatively with both random (R-PBAT) and aligned PBAT (A-PBAT) nanofibers coated films. The effect of polymer concentration, flow rate, applied voltage, and needle tip-connector distance on fiber diameter and alignment was examined in the electrospinning process and optimum processing parameters were determined by RSM. The PBAT nanofibers were spun on basement membranes with 10% (w/v) polymer concentration, 1 mL/h volumetric flow rate, 2000 rpm collector rotation velocity (for aligned ones), 15 kV applied voltage, and 20 cm needle tip-collector distance. The average diameter of random (R-PBAT) and aligned (A-PBAT) nanofibers was calculated as 555 ± 126 nm and 417 ± 137 nm. The mechanical test results showed that the alignment topography increased the elastic modulus of PBAT nanofibers compared to random matrices. The alignment of fibers found as 91% and 75% within the ± 10° range for A-PBAT/SC-PBAT and A-PBAT/SC-PCL, respectively. These findings showed that usage of PCL, instead of PBAT, as basement membrane decrease the alignment of deposited nanofibers. A 7-day cell culture study conducted with H9C2 cells seeded samples to investigate the influence of these differences on cell behavior. The results indicated that the alignment of fibers provides a suitable topography to proliferate and spread in myocyte morphology for H9C2 cells especially compared to neat films. Cellular behavior and nanofiber deposition have been affected by the usage of various basement membrane polymers. These findings demonstrated that the usage of basement membrane as support material provides the required thickness and mechanical properties to the aligned PBAT nanofiber matrices, and this double layer structure might be a promising candidate for cardiac tissue engineering with further studies.

Experimental study on co-culture of DiI labeled rat bone marrow mesenchymal stem cells and polycaprolactone film in vitro to make a cell patch.

In stem cell therapy, due to the lack of an effective carrier, a large number of transplanted stem cells are lost and die. Therefore, finding a suitable carrier has become a further direction of stem cell therapy. In research on the co-culture of polycaprolactone (PCL) with 1,1'-Dioctadecyl-3,3,3',3'- tetramethylindocarbocyanine perchlorate (DiI) labeled bone marrow mesenchymal stem cells (BMSCs), we observe the effect of materials on the growth and proliferation of DiI labeled stem cells, and the effect of DiI labeling on patch preparation, so as to find a kind of biomaterial suitable for the growth and proliferation of BMSCs, and find a suitable cell carrier for stem cell therapy of myocardial infarction and in vivo tracing. Clean grade Sprague Dawley rats were selected as experimental objects, BMSCs were isolated and cultured, and the surface markers were identified by flow cytometry. After the BMSCs were cultured for 3 passages, the BMSCs were stained with DiI dye, and the BMSCs DiI and PCL biomaterial film were co-cultured. After 24 hours, the cell growth was observed under fluorescence microscope, and fixed for scanning under electron microscope. The cell proliferation was detected by CCK-8 at 1, 4, 7, 10 days of culture. The measurement data conforming to normal distribution are expressed in the form of mean ± standard deviation (X¯±s). One way ANOVA was used for comparison among groups, LSD analysis was used for pairwise comparison. The difference was statistically significant (P <0.05). BMSCs were strongly positive for CD90, CD44H, but negative for CD11b/c, CD45. Under fluorescence microscope, BMSCs DiI showed red light, fusiform or polygonal. Under the scanning electron microscope, the cell patch formed by co-culture of PCL film and DiI-BMSCs had a large number of cells on the surface and normal cell state. CCK-8 assay showed that the OD value on the first day was 0.330 ± 0.025; The OD value was 0.620 ± 0.012 on the 4th day, 1.033 ± 0.144 on the 7th day and 1.223 ± 0.133 on the 10th day. There was significant difference among the time points (P <0.05). The cell patch made of PCL film and DiI labeled BMSCs can survive and proliferate on the surface, so it can be used as a scaffold material for stem cell therapy in vivo.

Fabrication of liquid metal loaded polycaprolactone conductive film for biocompatible and flexible electronics

Bioelectronics are crucial for monitoring physiological signals, managing chronic health conditions and assisting surgical procedures, which demand biocompatibility, high conductivity and flexibility. Here, we report a conductive film based on polycaprolactone (PCL) film and liquid metal nanoparticles (LMNPs), denoted as PCL@LMNPs film. We loaded LMNPs onto the nanofibers of PCL film by suction filtration and broke LMNPs through mechanical sintering. Rupture LMNPs formed conductive paths, which provides us opportunities to construct different electronics. The biocompatibility of PCL@LMNPs film was confirmed by skin irritation test on human skin and cell viability test with Hela cells. In addition, the film can be degraded in the simulated body fluid, proving its potential in implantable electronics. What is more, by analyzing resistance change while PCL@LMNPs films was deformed, we can monitor the different action with varied forces applied on the films. We demonstrated flexible sensors based on the PCL@LMNPs films, which can realize weight sensing, sound sensing and breath monitoring. The unique properties of the fabricated PCL@LMNPs films show a great future for use in biocompatible and flexible electronics.

Preparation of myocardial patches from DiI-labeled rat bone marrow mesenchymal stem cells and neonatal rat cardiomyocytes contact co-cultured on polycaprolactone film

To provide better treatment of myocardial infarction, DiI-labeled bone marrow mesenchymal stem cells (BMSCs) were contact co-cultured with cardiomyocytes (CMs) on polycaprolactone (PCL) film to prepare myocardial patches. BMSCs from Sprague Dawley rats were isolated, cultured, and characterized for expression of surface markers by flow cytometry. CMs were isolated from suckling rats. After BMSCs were cultured for three generations, they were labeled with DiI dye. DiI-labeled BMSCs were co-cultured with CMs on PCL film in the experimental group, while CMs were replaced with the same amount of unlabeled BMSCs in the control group. After 24 h, cell growth was observed by light microscopy and cells were fixed for scanning electron microscopy (SEM). After 7 d of co-culture, cells were stained for immunofluorescence detection of myocardial markers cardiac troponin T (cTnT) and α-actin. Differentiation of BMSCs on PCL was observed by fluorescence microscopy. The efficiency of BMSC differentiation into CMs was analyzed by flow cytometry on the first and seventh days of co-culture. CMs were stained with calcein alone and contact co-cultured with DiI-labeled BMSCs on PCL film to observe intercellular dye transfer. Finally, cells were stained for immunofluorescence detection of connexin 43 (Cx43) expression and to observe the relationship between gap junctions and contact co-culture. BMSCs were identified by flow cytometry as strongly positive for CD90 and CD44H, and negative for CD11b/c and CD45. After co-culture for 24 h, cells were observed to have attached to PCL by light microscopy. Upon appropriate excitation, DiI-labeled BMSCs exhibited red fluorescence, while unlabeled CMs did not. SEM revealed a large number of cells on the PCL membrane and their cell state appeared normal. On the seventh day, some DiI-labeled BMSCs expressed cTnT and α-actin. Flow cytometry showed that the rate of stem cell differentiation in the experimental group was significantly higher than the control group on the seventh day (20.12% > 3.49%, P < 0.05). From the second day of co-culture, immunofluorescence staining for Cx43 revealed green fluorescent puncta in some BMSCs; from the third day of co-culture, a portion of BMSCs exhibited green fluorescence in dye transfer tests. Contact co-culture of DiI-labeled BMSCs and CMs on PCL film generated primary myocardial patches. The mechanism by which contact co-culture promoted differentiation of the myocardial patch may be related to gap junctions and gap junction-mediated intercellular signaling pathways.

Indomethacin Sustained-Release Anti-adhesion Membrane Composed of a Phospholipid and Polycaprolactone Blend.

Postoperative peritoneal adhesions are among common challenging problems in surgery. The availability of limited efficient strategies to prevent intra-abdominal adhesion reinforces the need to explore new methods. Given the favorable prolonged drug release characteristics of polycaprolactone (PCL) films and their ability to act as a biodegradable physical barrier implant, along with the anti-inflammatory and anti-adhesion properties of indomethacin and phospholipids, this study hypothesized that indomethacin sustained-release membrane composed of phosphatidylcholine (PC) and PCL blend could efficiently prevent abdominal adhesion formation. Different polymeric and polymeric/lipidic hybrid formulations with three feeding materials to drug weight ratios were prepared, and their physicochemical characteristics and drug release kinetics were evaluated and compared. Abdominal adhesions were induced in 48 rats by the abrasion of the cecum and excision of a section of the opposite abdominal wall. Adhesion formation was evaluated by macroscopic scoring, histological, scanning electron microscopy, and polymerase chain reaction analyses. Both PCL and PCL-PC films exhibited sustained indomethacin release profiles. The X-ray diffraction and Fourier-transform infrared spectroscopy studies confirmed indomethacin incorporation in formulations in molecular dispersion form without any interaction. The films showed smooth surfaces and good mechanical properties. The treatment with indomethacin PCL-PC membrane significantly reduced the expression levels of tumor necrosis factor-alpha, transforming growth factor-beta, interleukin-1, interleukin-6, and fibrinogen in the adhesion tissues. The separation of the injured peritoneum, very low adhesion scores, and complete mesothelial cell regeneration were also achieved. This study suggests that indomethacin-eluting PCL-PC membrane acting through the combination of physical barrier, anti-inflammatory agents, and controlled drug delivery warrants an effective approach to prevent intra-abdominal adhesion.