Polycaprolactone Coatings Research Articles

3D printing of drug-eluting bioactive multifunctional coatings for orthopedic applications.

Three-dimensional (3D) printing is implemented for surface modification of titanium alloy substrates with multilayered biofunctional polymeric coatings. Poly(lactic-co-glycolic) acid (PLGA) and polycaprolactone (PCL) polymers were embedded with amorphous calcium phosphate (ACP) and vancomycin (VA) therapeutic agents to promote osseointegration and antibacterial activity, respectively. PCL coatings revealed a uniform deposition pattern of the ACP-laden formulation and enhanced cell adhesion on the titanium alloy substrates as compared to the PLGA coatings. Scanning electron microscopy and Fourier-transform infrared spectroscopy confirmed a nanocomposite structure of ACP particles showing strong binding with the polymers. Cell viability data showed comparable MC3T3 osteoblast proliferation on polymeric coatings as equivalent to positive controls. In vitro live/dead assessment indicated higher cell attachments for 10 layers (burst release of ACP) as compared to 20 layers (steady release) for PCL coatings. The PCL coatings loaded with the antibacterial drug VA displayed a tunable release kinetics profile based on the multilayered design and drug content of the coatings. Moreover, the concentration of active VA released from the coatings was above the minimum inhibitory concentration and minimum bactericidal concentration, demonstrating its effectiveness against Staphylococcus aureus bacterial strain. This research provides a basis for developing antibacterial biocompatible coatings to promote osseointegration of orthopedic implants.

Adhesion and corrosion resistance of polycaprolactone coating on NiTi alloy surface after alkali heat pretreatment

Selective laser melting of nickel-titanium alloy (SLM-NiTi) can precisely control the size of the sample molding structure and has attracted extensive attention due to its special superelasticity and shape memory effect. However, the biological inertness and poor corrosion resistance of SLM-NiTi alloy limit their wide application as biomedical implant materials. In this study, polycaprolactone (PCL) coating was prepared on SLM-NiTi alloy by dipping and pulling method, and the effects of alkali heat pretreatment on the morphology, adhesion, corrosion resistance, long-term stability and biomineralisation of the PCL coatings were investigated. The results showed that PCL coating can substantially improve the performance of SLM-NiTi alloy, and the PCL coating after alkali heat pretreatment has higher adhesion (increased from 1,747 to 2,498 mN) and lower corrosion current density (reduced by about an order of magnitude compared to PCL coating alone). In addition, the necessary stability, biomineralisation and biocompatibility ability of coatings were also further improved. Therefore, the alkali heat pretreated PCL-coated SLM-NiTi alloy has good application prospects in implants due to its superior properties.

Corrosion resistance and near-infrared light induced self-healing behavior of polycaprolactone coating with MIL-53@TA on magnesium alloy

A novel self-healing composite coating was fabricated on magnesium alloy by using polycaprolactone (PCL) as resin matrix and iron-based metal-organic framework MIL-53 modified with tannic acid (TA) as function filler. The surface morphology, structure and wettability of composite coating were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) and sessile water droplet static contact angle. The corrosion resistance and healing performance of PCL coatings was determined by electrochemical impedance spectroscopy (EIS) and photothermal tests. Results indicate that MIL-53@TA/PCL coating possesses a flatter surface, a higher corrosion resistance and better photothermal effect than that of blank PCL coating and MIL-53/PCL coating. Under the near-infrared (NIR) laser irradiation with the wave length of 808 nm, the scratched MIL-53@TA/PCL coating could be healed within 10 min because of the excellent photothermal conversion ability of MIL-53@TA component.

Albumin grafted coaxial electrosparyed polycaprolactone-zinc oxide nanoparticle for sustained release and activity enhanced antibacterial drug delivery.

One of the most serious issues faced by the healthcare sector is the development of multidrug resistance among various pathogens. It is such that developing new and more capable drugs takes far too long to counter such resistance. In order to overcome these concerns, this study focused on improving upon the coaxial electrospraying process by producing cloxacillin loaded albumin polycaprolactone (PCL) with a ZnO coating for sustained and activity enhanced drug delivery. Albumin-grafted, polycaprolactone-coated, zinc oxide-loaded cloxacillin (APCL-CLOX-ZnO) nanoparticles with a diameter of 85–110 nm were obtained via a coaxial electrospray technique. The encapsulation efficiency of cloxacillin of ZnO-CLOX was found to be approximately 60%. The loading efficiencies of ZnO-CLOX and APCL-CLOX-ZnO were found to be 40% and 28% respectively. Albumin was employed in order to impart immune evasion properties to the formulation. Drug-loaded ZnO NPs were analyzed using SEM, TEM, FT-IR and TGA. This novel formulation was shown to possess sustained release characteristics owing to the PCL and albumin coatings, relative to uncoated counterparts. ZnO-CLOX and APCL-CLOX-ZnO exhibited 72% and 52% cloxacillin release within 24 h. APCL-CLOX-ZnO exhibited potent antimicrobial activity against S. epidermidis, B. cereus and P. aeruginosa and some activity against E. coli with inhibition zones 32 ± 1.4, 34 ± 0.3, 32 ± 0.6 and 11 ± 0.4 mm, respectively. Cytotoxicity studies against murine preosteoblast cells revealed that the albumin-PCL coating served to drastically reduce initial toxicity against healthy mammalian cells. In vitro lung deposition study showed 70% of APCL-CLOX-ZnO particles can reach up to the alveoli level. Therefore, this novel coaxial nanoformulation may serve as a promising drug delivery platform for the treatment of bacterial infections including respiratory tract complications.

Improvement of Paper Resistance against Moisture and Oil by Coating with Poly(-3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and Polycaprolactone (PCL)

Surface hydrophobicity and grease resistance of paper may be achieved by the application of coatings usually derived from fossil-oil resources. However, poor recyclability and environmental concerns on generated waste has increased interest in the study of alternative paper coatings. This work focuses on the study of the performances offered by two different biopolymers, poly(3-hydroxybutyrate-co-3hydroxyvalerate) (PHBV) and polycaprolactone (PCL), also assessing the effect of a plasticizer (PEG) when used as paper coatings. The coated samples were characterized for the structural (by scanning electron microscopy, SEM), diffusive (water vapor and grease barrier properties), and surface properties (affinity for water and oil, by contact angle measurements). Samples of polyethylene-coated and fluorinated paper were used as commercial reference. WVTR of coated samples generally decreased and PHBV and PCL coatings with PEG at 20% showed interesting low wettability, as inferred from the water contact angles. Samples coated with PCL also showed increased grease resistance in comparison with plain paper. This work, within the limits of its lab-scale, offers interesting insights for future research lines toward the development of cellulose-based food contact materials that are fully recyclable and compostable.

3D printed hydrogel/PCL core/shell fiber scaffolds with NIR-triggered drug release for cancer therapy and wound healing

Hydrogel based scaffolds with the ability of on-demand drug delivery gained increasing interests for localized cancer therapy and tissue engineering application. However, most drug-loaded hydrogels are generally not suitable for long-term drug delivery, because of the uncontrolled diffusion of drugs from the swollen hydrogels. Therefore, in this study, a core/shell fiber scaffold was fabricated by coating a homogeneous layer of polycaprolactone (PCL) on the 3D printed alginate-gelatin hydrogel scaffolds. The PCL coatings could reduce the free diffusion of drugs from the core gels. Subsequently, polydopamine (PDA) was coated on the Gel/PCL core/shell scaffolds, endowing the scaffolds with great photothermal effects. Thus, near-infrared (NIR) laser triggered on-demand drug release was realized in this system due to the thermally induced sol-gel transition of the core gels. The released drugs (doxorubicin) and photothermal therapy could effectively prohibit or ablate tumor in vitro and in vivo. Additionally, the Gel/PCL/PDA core/shell scaffold could serve as platform for promoting wound healing. Therefore, the reported Gel/PCL/PDA core/shell scaffolds have the potential for application in localized cancer therapy and tissue regeneration. Especially for those cancer patients suffering surgical resection, the scaffolds could be implanted in the resection site to kill the residual or recurrent cancer cells, as well as to repair the tissue defects caused by surgery. Statement of significanceThis paper reported a facile strategy to realize stimuli-triggered on demand drug release in vitro and in vivo. Polycaprolactone (PCL) and polydopamine were sequentially deposited on the surface of 3D printed drug-loaded alginate/gelatin scaffold. PCL encapsulation could effectively reduce the free diffusion of drugs from the core hydrogel, achieving sustained drug release. Polydopamine with good photothermal effects endowed the scaffold with stimuli-triggered drug release in response to near-infrared (NIR) laser irradiation. This scaffold could be applied for localized cancer therapy and tissue regeneration. Especially for those cancer patients suffering surgical resection, the scaffolds could be implanted in the resection site to kill the residual or recurrent cancer cells, as well as to repair the tissue defects caused by surgery.

Fabrication of 3D monolithic graphene foam/polycaprolactone porous nanocomposites for bioapplications

Aiming at the production of light, porous, conductive, biosafe composites, in this paper we are presenting a novel fabrication method for monolithic, three-dimensional (3D) graphene foam (GF)/porous polymer composites. The synthesis adopts a novel process architecture by using Ni foam templates in an inductive heating chemical vapor deposition growth process, and by removing Ni chemically while retaining graphene integrity by the reversible application of cyclododecane (CD); finally, nondestructive coating procedures with polycaprolactone (PCL) solutions have been developed. The composites can be optimized to enhance electrical conduction, flexibility and mechanical properties, while mixing PCL and CD allows to coat the GF with a novel mesoporous polymer coating. By tuning the GF properties, the typical electrical resistance of the 3D forms can be reduced to a few 10 s of Ohms, values that are maintained after the PCL coatings. The current study achieved a GF fraction ranging between 1 and 7.3 wt%, with even the lower graphene content composites showing acceptable electrical and mechanical properties. The properties of these conductive 3D-GF/PCL composites are in line with the requirements for applications in the field of nerve tissue engineering.Graphical abstract

Electrochemical and bioactive evaluation of polycaprolactone/multi-walled carbon nanotubes coatings on titanium alloy

Composite materials of polymer – carbon nanotubes have been widely studied for biomedical applications due to the versatility of polymers in this field and the excellent mechanical, thermal and electrical properties of carbon nanotubes. However, carbon nanotubes are materials which can provide some toxicity in biological systems, since they have low solubility in water and organic solvents, tend to form aggregates in solution, are bioincompatible and limited compatibility with polymeric matrices. For this reason, carbon nanotubes considered for biomedical applications must comply with this basic requirement of solubility. To improve the compatibility of the carbon nanotubes, they were exposed to treatment with HNO3, NaOH and HCl to eliminate impurities and improve the solubility in other solvents. Polycaprolactone coatings at 2.5% w/v and multi-wall carbon nanotubes (0.5, 1.0 and 1.5 g/L) were developed to evaluate the electrochemical and bioactive properties. Techniques such as infrared spectroscopy, contact angle, scanning electron microscopy, atomic force microscopy, electrochemical impedance spectroscopy using simulated body fluid as electrolyte and the bioactivity of human osteoseosarcoma cells (HOS ATCC® CRL-1543) by alkaline phosphatase were used. From the reported characterizations, it was observed that the resistance to polarization increases according to the degree of dispersion of carbon nanotubes present in the polymer matrix, decreasing the degradation rate of the material.

Iron surface functionalization system - Iron oxide nanostructured arrays with polycaprolactone coatings: Biodegradation, cytocompatibility, and drug release behavior

Abstract A surface functionalization system targeted for iron-based materials is developed by combining two biodegradable components, iron oxide nanostructured arrays and polycaprolactone (PCL) coatings. Iron oxide nanoporous and nanotubular arrays are superior surface functionalization matrices, while their stability and cytocompatibility can be further improved by PCL coatings, the morphology of which can modify the drug release behavior. The biodegradation behavior of this system was investigated firstly by electrochemical tests, and further biodegradation information (including the surface morphology and chemical composition) was collected from samples used in a long-term in vitro cytocompatibility test over 21 days of incubation with human adipose-derived stem cells (ADSCs). Moreover, the drug release behavior of these arrays coated with various PCL coatings was studied using tetracycline as a model drug. Experimental results demonstrate that PCL coatings can endow iron oxide nanostructured arrays a proper biodegradation behavior with bioactive degradation products on the surface, also leading to high cytocompatibility characterized by the production of collagen type I and cell distribution on the PCL-coated samples. Furthermore, with the barrier effect of PCL, the whole functionalization system shows sustainable drug release behavior.

X-ray computed tomography of multiple-layered scaffolds with controlled gradient cell lattice structures fabricated via additive manufacturing

In this paper we report on the characterization by X-ray computed tomography of calcium phosphate (CaP) and polycaprolactone (PCL) coatings on Ti-6Al-4V alloy scaffolds used as a material for medical implants. The cylindrical scaffold has greater porosity of the inner part than the external part, thus, mimicking trabecular and cortical bone, respectively. The prismatic scaffolds have uniform porosity. Surface of the scaffolds was modified with calcium phosphate (CaP) and polycaprolactone (PCL) by dip-coating to improve biocompatibility and mechanical properties. Computed tomography performed with X-ray and synchrotron radiation revealed the defects of structure and morphology of CaP and PCL coatings showing small platelet-like and spider-web-like structures, respectively.

Formation of calcium phosphate coatings within polycaprolactone scaffolds by simple, alkaline phosphatase based method

The paper presents a novel approach to the production of calcium phosphate coatings of scaffolds. Mineral deposits were formed during incubation of polycaprolactone (PCL) scaffolds with bovine intestinal alkaline phosphatase in sodium glycerophosphate and calcium chloride medium. To modify hydrophobic surface of scaffolds and intensify attachment of coating, scaffolds were incubated at 50 °C (thermal activation, TA) or at 37 °C after short exposition to lipase (lipase activation, LA). Micro-computed tomography observations demonstrated that both methods resulted in deposition of mineral on the surface of external and internal walls of the scaffolds. Precipitate formed after thermal and lipase activation contained particles with average size of 200–400 nm, and the shape of donuts. In thermal activated PCL coatings X-ray diffraction disclosed peaks typical for hydroxyapatite (HAp), while after lipase activation these peaks could be precisely defined only if left for 6 days in the incubation medium. The Fourier-transform infrared spectroscopy suggested crystalline structure of HAp both after thermal and lipase activation. The adherence of bone marrow mesenchymal stem cells was initially higher on coated than pristine PCL, but during 7 days of culture the cell number increased and was similar on all tested samples. Alkaline phosphatase activity, considered as a sign of osteogenic differentiation, measured on PCL samples after 7 days was 2–3 times lower on pristine PCL than on the coated samples, but after 2 weeks increased significantly and reached similar value as on the calcium phosphate substrates.

Cu-releasing bioactive glass/polycaprolactone coating on Mg with antibacterial and anticorrosive properties for bone tissue engineering

Bioactive glass nanoparticles containing copper (Cu-BGNs) were introduced into polycaprolactone (PCL) coating systems to improve the bioactivity, antibacterial properties, and corrosion resistance of vulnerable magnesium matrices under physiological conditions. The influence of different amounts of Cu-BGNs in PCL coatings was thoroughly investigated in determining the wettability, electrochemical properties, and antibacterial effects against Staphylococcus carnosus and Escherichia coli, as well as their cyto-compatibility. Cu-BGNs were observed randomly scattered in PCL coatings. Increasing the concentration of Cu-BGNs resulted in a slight decrease of the water contact angle, and a reduction in anticorrosion properties of the Cu-BGN composite coatings. Yet higher Cu-BGN content in coatings led to more calcium phosphate formation on the surface after 7 days of immersion in Dulbecco’s modified Eagle’s medium, which was confirmed by Fourier-transform infrared spectroscopy and x-ray photoelectron spectroscopy. The growth of S. carnosus and E. coli was inhibited by Cu2+ ions released from the Cu-BGN coatings. In addition, both direct and indirect cyto-compatibility experiments showed that the viability and proliferation of MG-63 cells on Cu-BGN coatings were highly increased compared to pure magnesium; however, an additional increase of Cu-BGN concentration showed a slight decrease of cell proliferation and cell activity. In summary, Cu-BGN/PCL composite coatings impart magnesium-based biomaterials with antibacterial and anticorrosive properties for clinical applications.

Effects of polycaprolactone coating on the biodegradable behavior and cytotoxicity of Mg-6%Zn-10%Ca3(PO4)2 composite in simulated body fluid

Mg-6%Zn-10%Ca3(PO4)2 composite was prepared through powder metallurgy methods with polycaprolactone(PCL) coating on its surface. The properties of the PCL coatings on the surface of Mg-6%Zn-10%Ca3(PO4)2 composite, such as surface morphology, the corrosion behavior and the cytotoxicity properties were investigated. The results show that PCL coating improves the corrosion resistance of the magnesium matrix composite specimens significantly. Mg-6%Zn-10%Ca3(PO4)2 composite specimens with PCL coating exhibit good corrosion resistance and low pH values in SBF at 37°C in the immersion test, as compared with uncoated specimens. The cytotoxicity tests indicate Mg-6%Zn-10%Ca3(PO4)2 with PCL coating is nontoxic with higher relative growth rate than that of uncoated composites against L-929 cells.

Electrochemical Investigations of Polycaprolactone-Coated AZ31 Mg Alloy in Earle’s Balance Salt Solution and Conventional Simulated Body Fluid

Polycaprolactone (PCL) coating has been shown to increase the corrosion resistance of magnesium alloys when exposed to a simulated body fluid. A PCL dip coating was applied to AZ31 Mg alloy. Samples were immersed in both Earle’s Balance Salt Solution (EBSS) and conventional simulated body fluids (c-SBF) up to 14 days. Microscopic morphology, electrochemical impedance spectroscopy, and potentiodynamic polarization tests were performed to evaluate the corrosion behavior changes of PCL coatings against immersion times in EBSS and c-SBF as compared to the uncoated AZ31 substrate. PCL-coated samples demonstrated improved corrosion resistance compared to bare AZ31 in both EBSS and c-SBF, indicating that the PCL coating exhibited good corrosion protection of AZ31 in simulated body fluid. Samples immersed in EBSS showed significantly higher electrochemical impedance values and slower corrosion progression as compared to the samples in c-SBF, because of the decreased chloride content and CO2 buffering mechanism of the EBSS.

Stiffness Improvement of 45S5 Bioglass®‐Based Scaffolds Through Natural and Synthetic Biopolymer Coatings: An Ultrasonic Study

ABSTRACTDue to its excellent bioactivity, 45S5 Bioglass® is being highly considered in tissue engineering scaffold development. In order to enhance vascularization promoting tissue growth, these scaffolds typically have a highly interconnected porous structure with a porosity between 80 and >90%. Often, Bioglass®‐based scaffolds of such a high porosity have insufficient stiffness. In order to increase the stiffness of Bioglass®‐based scaffolds fabricated by the foam replica method, the herein investigated scaffolds were coated with a number of different biopolymers, including: collagen, gelatin, polycaprolactone (PCL), alginate and poly(l‐lactic acid). The resulting stiffness gain was quantified by means of ultrasonic measurements. Accordingly, PCL and collagen coatings increased the scaffold stiffness, as compared to uncoated scaffolds, by 58 and 38%, respectively; while no remarkable stiffness increase was recorded for the other coatings. Additionally, scanning electron microscopy images of polymer coated scaffolds revealed that PCL coatings had not clogged the scaffold's micropores, which is deemed essential for cell seeding and to enable in‐growth of bone tissue. Thus, the application of PCL coatings represents a promising strategy for mechanical competence enhancement of Bioglass®‐based scaffolds for bone tissue engineering.