Development of electrospun photocatalytic TiO2-polyamide-12 nanocomposites

Titanium dioxide (TiO2) in different forms such as films, fibers or particles are being extensively studied for removal of contaminants from aquatic environments due to its outstanding photocatalytic activity. This work reports the development of TiO2-polyamide 12 electrospun fiber mats. A systematic study on the influence of electrospun processing parameters on polymer fiber morphology was performed. It was observed that the average fiber diameter is mainly influenced by polymer concentration and average fiber diameters between 404 ± 82 nm and 1442 ± 360 nm were obtained. Polyamide-12 (PA-12) was used as a polymer matrix and electrospun with 0, 10 and 20 wt% of TiO2. It was observed that the filler does not change the average fiber diameter, being similar to that observed for neat PA-12 fibers processed under the same experimental conditions. The TiO2 were particles dispensed not only in the bulk of the polymeric matrix but also on the surface of the fibers, especially for the samples with higher filler contents. Neat and nanocomposite electrospun samples show a hydrophobic behavior and a degree of crystallinity of ~25%. The photocatalytic performance of the processed samples was measured by following the degradation capability of a chosen dye, methylene blue (MB). Results show that the nanocomposite samples have a remarkable photocatalytic activity, especially the one with a higher load of TiO2 particles (20 wt%), with all MB being removed from the solution after 100 min.This work was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/ UI607/2014, and CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnol ogico e Brazil). The authors also thank funding from “Matepro eOptimizing Materials and Processes”, ref. NORTE- 07-0124-FEDER-000037”, co-funded by the “Programa Operacional Regional do Norte” (ON.2 e O Novo Norte), under the “Quadro de Refer^encia Estrat egico Nacional” (QREN), through the “Fundo Europeu de Desenvolvimento Regional” (FEDER). PM thanks the FCT for the, SFRH/BD/98616/2013 grant. VS and SLM also thank support from the COST Action MP1206 “Electrospun Nano-fibers for bio inspired composite materials and innovative industrial applications”. VS thanks the EIS Faculty at UOW for the starting grant

Assessment of parameters influencing fiber characteristics of electrospun Poly(ethyl methacrylate) scaffolds

This work evaluates the influence of electrospinning process parameters on the mean diameter and standard deviation of fiber diameters in electrospun poly(ethyl methacrylate) (PEMA). Processing conditions were selected using Taguchi's statistical method. Oriented and unoriented electrospun mats with good mechanical properties were produced and demonstrated with tensile stress-strain diagrams. Differential scanning calorimetry (DSC) experiments showed that the polymer chains were forced into non-equilibrium conformations due to electrospinning. Enthalpic recovery during a heating scan is shown by an endothermic peak in the initial DSC heating scan that disappears in subsequent heating scans. An increase in the glass transition temperature with respect to PEMA films shows that the polymer is not equilibrated by heating above glass transition. Cell attachment was tested with MC3T3-E1 pre-osteoblastic cells cultured for short time periods on the electrospun mats. It is shown that the cells present less extended morphology with more diffuse perimetral focal adhesions than cells cultured on flat substrates. A tendency of cells to align in the direction of the substrate fibers in oriented electrospun membranes was also found. © 2010 Elsevier Ltd. All rights reserved.The language revision of this paper was funded by the Universidad Politecnica de Valencia, Spain.Gómez-Tejedor, JA.; Van Overberghe, N.; Rico Tortosa, PM.; Gómez Ribelles, JL. (2011). Assessment of parameters influencing fiber characteristics of electrospun Poly(ethyl methacrylate) scaffolds. EUROPEAN POLYMER JOURNAL. 47(2):119-129. https://doi.org/10.1016/j.eurpolymj.2010.10.034S11912947

Electrospray deposition and direct patterning of polylactic acid nanofibrous microcapsules for tissue engineering

Electrospun nanofibers composed of biodegradable polymers are attractive candidates for cell culture scaffolds in tissue engineering. Their fine-meshed structures, resembling natural extracellular matrices, effectively interact with cell surfaces and promote cell proliferation. The application of electrospinning, however, is limited to two-dimensional (2D) or single tube-like scaffolds, and the fabrication of arbitrary three-dimensional (3D) scaffolds from electrospun nanofibers is still very difficult due to the fibers’ continuous and entangled form. To address this issue, in this paper, we describe the use of phase-separation-assisted electrospray and electrostatic focusing to perform continuous direct 3D patterning of nanofibrous microcapsules of biodegradable polylactic acid (PLA). These microcapsules exhibit fiber-particle duality because they are composed of nanofibers suitable for cell attachment while also being easy to handle as particles for direct 3D patterning. By varying the flow rate of the polymer solution and the humidity of the electrospray atmosphere during electrospraying, the diameter of the microcapsule and its surface porosity can be controlled. The utility of the direct-patterning process is demonstrated by fabricating high-aspect-ratio microscaffolds and subsequent cell cultures. The nanofibrous and hollow structure of the microcapsules combined with the direct 3D patterning process offers a new approach for fabricating tailor-made scaffolds for regenerative medicine

Gyrospun antimicrobial nanoparticle loaded fibrous polymeric filters

© 2016 The Authors. Published by Elsevier B.V. © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).A one step approach to prepare hybrid nanoparticle embedded polymer fibres using pressurised gyration is presented. Two types of novel antimicrobial nanoparticles and poly (methylmethacrylate) polymer were used in this work. X-ray diffraction analysis of the nanoparticles revealed Ag, Cu and W are the main elements present in them. The concentration of the polymer solution and the nanoparticle concentration had a significant influence on the fibre diameter, pore size and morphology. Fibres with a diameter in the range of 6-20 ìm were spun using 20 wt% polymer solutions containing 0.1, 0.25 and 0.5 w% nanoparticles under 0.3 MPa working pressure and a rotational speed of 36000 rpm. Continuous, bead-free fibre morphologies were obtained for each case. The pore size in the fibres varied between 36-300 nm. Successful incorporation of the nanoparticles in polymer fibres was confirmed by energy dispersive x-ray analysis. The fibres were also gyrospun on to metallic disks to prepare filters which were tested for their antibacterial activity on a suspension of Pseudomonas aeruginosa. Nanoparticle loaded fibres showed higher antibacterial efficacy than pure poly(methylmethacrylate) fibres.8pÍuPeer reviewedFinal Published versio

3D imaging of cell interactions with electrospun PLGA nanofiber membranes for bone regeneration

We acknowledge funding from the QMUL Pump-Priming Research Funding for Cross-Faculty Initiatives 2011-12 (EPSRC

Nanostructured Biomaterials for Tissue Engineered Bone Tissue Reconstruction

Bone tissue engineering strategies are emerging as attractive alternatives to autografts and allografts in bone tissue reconstruction, in particular thanks to their association with nanotechnologies. Nanostructured biomaterials, indeed, mimic the extracellular matrix (ECM) of the natural bone, creating an artificial microenvironment that promotes cell adhesion, proliferation and differentiation. At the same time, the possibility to easily isolate mesenchymal stem cells (MSCs) from different adult tissues together with their multi-lineage differentiation potential makes them an interesting tool in the field of bone tissue engineering. This review gives an overview of the most promising nanostructured biomaterials, used alone or in combination with MSCs, which could in future be employed as bone substitutes. Recent works indicate that composite scaffolds made of ceramics/metals or ceramics/polymers are undoubtedly more effective than the single counterparts in terms of osteoconductivity, osteogenicity and osteoinductivity. A better understanding of the interactions between MSCs and nanostructured biomaterials will surely contribute to the progress of bone tissue engineering

Rough Fibrils Provide a Toughening Mechanism in Biological Fibers

Spider silk is a fascinating natural composite material. Its combination of strength and toughness is unrivalled in nature, and as a result, it has gained considerable interest from the medical, physics, and materials communities. Most of this attention has focused on the one to tens of nanometer scale: predominantly the primary (peptide sequences) and secondary (β sheets, helices, and amorphous domains) structure, with some insights into tertiary structure (the arrangement of these secondary structures) to describe the origins of the mechanical and biological performance. Starting with spider silk, and relating our findings to collagen fibrils, we describe toughening mechanisms at the hundreds of nanometer scale, namely, the fibril morphology and its consequences for mechanical behavior and the dissipation of energy. Under normal conditions, this morphology creates a nonslip fibril kinematics, restricting shearing between fibrils, yet allowing controlled local slipping under high shear stress, dissipating energy without bulk fracturing. This mechanism provides a relatively simple target for biomimicry and, thus, can potentially be used to increase fracture resistance in synthetic materials