A comparison study between electrospun polycaprolactone and piezoelectric poly(3-hydroxybutyrate-co-3-hydroxyvalerate) scaffolds for bone tissue engineering

This study was supported by the Federal Target Program #14.587.21.0013 (a unique application number 2015-14-588-0002-5599)

Low-temperature argon and ammonia plasma treatment of poly-3-hydroxybutyrate films: Surface topography and chemistry changes affect fibroblast cells in vitro

Poly-3-hydroxybutyrate (PHB) films were plasma-treated using pure NH3, pure Ar or mixtures of the two different proportions (20%, 30%, 40%, 50%, 70% NH3 in Ar). Surface chemistry and surface topography changes of PHB films were observed after plasma processing in all plasma regimes. The XPS results confirmed the absence of chemical modification in the case of pure Ar plasma treatment. Nitrogen-containing groups (e.g., N–C[dbnd]O) were detected on the surfaces of P3HB films treated with NH3-containing plasma. The surfaces of the untreated P3HB films were hydrophobic, and plasma treatment turned the surfaces hydrophilic, irrespective of the treatment. A significant decrease in the contact angle and an increase in the free surface energy were observed. An insignificant surface ageing effect was observed when P3HB samples were exposed to air for 10 days. In NIH 3T3 mice fibroblast cells, cell adhesion was significantly improved after plasma treatment in an Ar atmosphere, which is likely related to the fact that there was a surface ξ potential of 88.6 mV at neutral pH, causing a cleavage of the polymer chains and an increase in surface roughness

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

This article reports on a study of the mineralisation behaviour of CaCO3 deposited on electrospun poly(ϵ-caprolactone) (PCL) scaffolds preliminarily treated with low-temperature plasma. This work was aimed at developing an approach that improves the wettability and permeability of PCL scaffolds in order to obtain a superior composite coated with highly porous CaCO3, which is a prerequisite for biomedical scaffolds used for drug delivery. Since PCL is a synthetic polymer that lacks functional groups, plasma processing of PCL scaffolds in O2, NH3, and Ar atmospheres enables introduction of highly reactive chemical groups, which influence the interaction between organic and inorganic phases and govern the nucleation, crystal growth, particle morphology, and phase composition of the CaCO3 coating. Our studies showed that the plasma treatment induced the formation of O- and N-containing polar functional groups on the scaffold surface, which caused an increase in the PCL surface hydrophilicity. Mineralisation of the PCL scaffolds was performed by inducing precipitation of CaCO3 particles on the surface of polymer fibres from a mixture of CaCl2- and Na2CO3-saturated solutions. The presence of highly porous vaterite and nonporous calcite crystal phases in the obtained coating was established. Our findings confirmed that preferential growth of the vaterite phase occurred in the O2-plasma-treated PCL scaffold and that the coating formed on this scaffold was smoother and more homogenous than those formed on the untreated PCL scaffold and the Ar- and NH3-plasma-treated PCL scaffolds. A more detailed three-dimensional assessment of the penetration depth of CaCO3 into the PCL scaffold was performed by high-resolution micro-computed tomography. The assessment revealed that O2-plasma treatment of the PCL scaffold caused CaCO3 to nucleate and precipitate much deeper inside the porous structure. From our findings, we conclude that O2-plasma treatment is preferable for PCL scaffold surface modification from the viewpoint of use of the PCL/CaCO3 composite as a drug delivery platform for tissue engineering. © 2018 The Royal Society of Chemistry

Structural Evolution of PCL during Melt Extrusion 3D Printing

Screw-assisted material extrusion technique is developed for tissue engineering applications to produce scaffolds with well-defined multiscale microstructural features and tailorable mechanical properties. In this study, in situ time-resolved synchrotron diffraction is employed to probe extrusion-based 3D printing of polycaprolactone (PCL) filaments. Time-resolved X-ray diffraction measurements reveals the progress of overall crystalline structural evolution of PCL during 3D printing. Particularly, in situ experimental observations provide strong evidence for the development of strong directionality of PCL crystals during the extrusion driven process. Results also show the evidence for the realization of anisotropic structural features through the melt extrusion-based 3D printing, which is a key development toward mimicking the anisotropic properties and hierarchical structures of biological materials in nature, such as human tissues

Plasma surface modification and bonding enhancement for bamboo composites

This paper presents plasma technology for the functionalization of both carbonized and non-carbonized bamboo surfaces, including bamboo skin, pulp, pith and mixed bamboo groups, for the production of advanced bamboo composites. Oxygen, nitrogen and argon are used as the plasma gas resources, and various plasma powers, gas pressures and treatment times investigated. Surface composition, morphology and wettability of plasma treated bamboos are characterized by using Fourier transform infrared spectroscopy (FTIR) and ESEM to understand the mechanisms of plasma treatment and chemical and physical changes of bamboo surface layer, and interface bond of bamboo composites. Results showed that the efficacy of plasma treatment was bamboo skin > pith > pulp and carbonized > non-carbonized, resulting in different surface characteristics and subsequent interface bonds of bamboo with the optimum plasma parameters being the processing time of 103s, the power of 141W and gas pressure of 38Pa. Oxygen plasma treatment generated an effective surface oxidization and oxygen-containing groups, resulted in significant change in (micro)structure of bamboo surface layer, and led to a significant improvement in the wetteability and interface bonding of bamboo surface and hence physical and mechanical properties of bamboo composites, e.g. MOR of 170 MPa with about 47% increase over untreated bamboo composites. Bamboo composites should be produced with efficacy period of 3 days after plasma treatment for the carbonized and 5 days for non-carbonized bamboo