Francesca Intranuovo

Improved osteoblast cell affinity on plasma-modified 3-D extruded PCL scaffolds

Cellular adhesion and proliferation inside three-dimensional synthetic scaffolds represent a major challenge in tissue engineering. Besides the surface chemistry of the polymers, it is well recognized that scaffold internal architecture, namely pore size/shape and interconnectivity, has a strong effect on the biological response of cells. This study reports for the first time how polycaprolactone (PCL) scaffolds with controlled micro-architecture can be effectively produced via bioextrusion and used to enhance the penetration of plasma deposited species. Low-pressure nitrogen-based coatings were employed to augment cell adhesion and proliferation without altering the mechanical properties of the structures. X-ray photoelectron spectroscopy carried out on different sections of the scaffolds indicates a uniform distribution of nitrogen-containing groups throughout the entire porous structure. In vitro biological assays confirm that plasma deposition sensitively promotes the activity of Saos-2 osteoblast cells, leading to a homogeneous colonization of the PCL scaffolds.

Detection beyond Debye's length with an electrolyte-gated organic field-effect transistor.

Electrolyte-gated organic field-effect transistors are successfully used as biosensors to detect binding events occurring at distances from the transistor electronic channel that are much larger than the Debye length in highly concentrated solutions. The sensing mechanism is mainly capacitive and is due to the formation of Donnans equilibria within the protein layer, leading to an extra capacitance (CDON) in series to the gating system.

Uniform cell colonization of porous 3-D scaffolds achieved using radial control of surface chemistry

Uniform cellular distribution is a prerequisite to forming tissue within porous scaffolds, but the seeding process often results in preferential adhesion of cells at the periphery. We develop a vapour phase coating strategy which is readily applicable to any porous solid to provide a uniform cellular distribution. Plasma polymerized allyl amine (ppAAm) is used to form a thin nitrogen-containing coating throughout porous three-dimensional (3-D) poly(d,l-lactic acid) scaffolds. Subsequent controlled deposition of a hydrocarbon plasma polymerized hexane (ppHex) allows control of the fibroblast penetration into these porous 3-D objects. In order to optimize the coating conditions, a planar pinhole model of plasma penetration into pores is developed to rapidly measure deposit penetration using picolitre water contact angle measurement. Sufficiently good control over the plasma deposition within the porous scaffold is achieved using this approach to superimpose a relatively cell-repellent ppHex coating at the scaffold periphery onto the ppAAm-coated core, with a chemical gradient between the two. This 3-D chemical gradient encourages 3T3 fibroblast cells to adhere homogeneously from the periphery to the centre, when balanced by the tortuousity of the pore structure, which cells experience when passing from the surrounding medium to the centre.

Osteoblast-like cell behavior on plasma deposited micro/nanopatterned coatings.

The behavior of cells in terms of cell-substrate and cell-cell interaction is dramatically affected by topographical characteristics as shape, height, and distance, encountered in their physiological environment. The combination of chemistry and topography of a biomaterial surface influences in turns, important biological responses as inflammatory events at tissue-implant interface, angiogenesis, and differentiation of cells. By disentangling the effect of material chemistry from the topographical one, the possibility of controlling the cell behavior can be provided. In this paper, surfaces with different roughness and morphology were produced by radiofrequency (RF, 13.56 MHz) glow discharges, fed with hexafluoropropylene oxide (C(3)F(6)O), in a single process. Coatings with different micro/nanopatterns and the same uppermost chemical composition were produced by combining two plasma deposition processes, with C(3)F(6)O and tetrafluoroethylene (C(2)F(4)), respectively. The behavior of osteoblast-like cells toward these substrates clearly shows a strict dependence of cell adhesion and proliferation on surface roughness and morphology.

Plasma Assisted Surface Modification Processes for Biomedical Materials and Devices

This contribution reviews cold plasma processes that are investigated and utilized in academic and technological fields related to Life Sciences, in particular for tailoring surface composition and morphology of materials of different utilization in Medicine and Biology for implants, prostheses, biosensors, devices and scaffolds for tissue engineering. The final goal of the research in this field is, in general, to achieve the capability of driving at will the behaviour (adhesion, growth, morphology, physiology, etc.) of cells and biological tissues in vitro and in vivo at the surface of modified materials.

A comparison of 3D poly(ε-caprolactone) tissue engineering scaffolds produced with conventional and additive manufacturing techniques by means of quantitative analysis of SR μ-CT images

The technique used to produce a 3D tissue engineering (TE) scaffold is of fundamental importance in order to guarantee its proper morphological characteristics. An accurate assessment of the resulting structural properties is therefore crucial in order to evaluate the effectiveness of the produced scaffold. Synchrotron radiation (SR) computed microtomography (μ-CT) combined with further image analysis seems to be one of the most effective techniques to this aim. However, a quantitative assessment of the morphological parameters directly from the reconstructed images is a non trivial task. This study considers two different poly(e-caprolactone) (PCL) scaffolds fabricated with a conventional technique (Solvent Casting Particulate Leaching, SCPL) and an additive manufacturing (AM) technique (BioCell Printing), respectively. With the first technique it is possible to produce scaffolds with random, non-regular, rounded pore geometry. The AM technique instead is able to produce scaffolds with square-shaped interconnected pores of regular dimension. Therefore, the final morphology of the AM scaffolds can be predicted and the resulting model can be used for the validation of the applied imaging and image analysis protocols. It is here reported a SR μ-CT image analysis approach that is able to effectively and accurately reveal the differences in the pore- and throat-size distributions as well as connectivity of both AM and SCPL scaffolds.

Plasma Processing of Scaffolds for Tissue Engineering and Regenerative Medicine

Abstract Plasma processes are largely employed in the biomedical field for different kind of materials. In particular, in tissue engineering, biomaterials need to be totally integrated with biological systems in order to be employed as substitutes of artificial prostheses. Since most materials do not allow a correct integration with the biological environment, plasma processes have been demonstrated to be very versatile in altering the material surface properties in order to improve the biocompatibility of materials. The challenge is to plasma modify 3D scaffolds in order to be used for in vivo regeneration of human tissues. The correct 3D biointegration inside living tissues is the crucial objective, towards which many aspects are directed, from the material engineering to its surface modification and affinity with the biological environment. In this paper, the advances in low pressure plasma processes, applied to both 2D rigid substrates and 3D porous structures, are discussed. Further an in vivo experiment in ovine animals using plasma processed 3D scaffolds is illustrated.