Electrospinning of natural polymers for advanced wound care: towards responsive and adaptive dressings

In the last few years, the health-care services have registered worldwide an increased number of patients suffering from chronic wounds and ulcers, which are mainly associated with diabetes, obesity and cancer. The need for regenerating rapidly and effectively the injured skin has stimulated the research of advanced therapies for wound care. This review will discuss how biomimetic architectures produced by electrospinning natural biopolymers fulfil most of the requirements of ideal wound dressings. It will also examine the recent progress in the area of portable electrospinning systems and of multiscale instructive materials that integrate stimuli responsive and sensing elements

Phase separation events induce the coexistence of distinct nanofeatures in electrospun fibres of poly(ethyl cyanoacrylate) and polycaprolactone

© 2018 Elsevier Ltd Here we show that thermodynamic instabilities during electrospinning of polymer blends of poly(ethyl cyanoacrylate) (PECA) and polycaprolactone (PCL) in a ternary solvent system (acetone/chloroform/acetonitrile) induce the formation of hierarchical composite fibres with dual porosity. The analysis of the surface and cross-section of the PECA-PCL fibres reveals that, differently from previous works, the electrospun fibres are formed of two distinct morphologies: half of the fibre exhibits parallel and elongated grooves; whereas the other half has near-circular shaped pores. Porosity is present throughout the fibre volume with some regions being hollow. The occurrence of this novel architecture is investigated using different solvent systems and a dual phase separation mechanism is proposed. Porous fibres with a hierarchical porous structure are beneficial in many fields, including biomedical, environmental and energy related applications

Effect of antibacterial plant extracts on the morphology of Electrospun Poly(Lactic Acid) fibres

Essential oils (EOs) of clary sage and black pepper induce changes in the morphology of poly(lactic acid) (PLA) electrospun fibres. The chemical composition of the oils is analysed by gas chromatography-mass spectrometry and Fourier-transform infrared spectroscopy; while the evaporation rate of the EOs and their main chemical components is characterised by Thermogravimetric Analysis. The addition of EOs generate thermodynamic instabilities during the electrospinning process, leading to the formation of fibres with either wrinkled (for clary sage oil) or nano-textured surfaces (for black pepper oil). The morphology of the PLA-EOs fibres is investigated by Scanning Electron Microscopy. Together with a well-defined structure, the fibres produced also possess antibacterial activity, as demonstrated by viability loss tests conducted on E. coli and S. epidermidis. Bacteria inactivation efficiency of 76 and 100% is reported for the composite PLA/essential oils electrospun mats. The composite mats produced are promising in the biomedical field, where nanotopography offers physical cues to regulate cell behaviour, and the delivery of therapeutic compounds (essential oils) limits microbial growth

Structural relaxation in PLLA: Contribution of different scale motions

The enthalpy relaxation in amorphous and semi-crystalline poly(L-lactic acid) (PLLA) has been investigated at low and high undercooling to identify the different scale motions that contribute to physical ageing, and the temperature ranges in which they are active. The temperature limit below which exclusively small-scale localized motions produce structural relaxation in PLLA has been identified. In addition, motions different from pure cooperative large-scale motions and pure small-scale local rearrangements, localized in the mobile amorphous fraction, are found to mainly contribute to structural relaxation at intermediate undercoolings. These motions are suggested to be related with the Johari-Goldstein process

Electrospun nanofibres containing antimicrobial plant extracts

Over the last 10 years great research interest has been directed toward nanofibrous architectures produced by electrospinning bioactive plant extracts. The resulting structures possess antimicrobial, anti-inflammatory, and anti-oxidant activity, which are attractive for biomedical applications and food industry. This review describes the diverse approaches that have been developed to produce electrospun nanofibres that are able to deliver naturally-derived chemical compounds in a controlled way and to prevent their degradation. The efficacy of those composite nanofibres as wound dressings, scaffolds for tissue engineering, and active food packaging systems will be discussed

Atomic-scale clustering inhibits the bioactivity of fluoridated phosphate glasses

© 2019 Adja B. R. Touré et al. Here, molecular dynamics simulations have been carried out on phosphate glasses to clarify the previously debated influence of fluoride on the bioactivity of these glasses. We developed a computationally advanced inter-atomic force field including polarisation effects of the fluorine and oxygen atoms. Structural characterisations of the simulated systems showed that fluoride ions exclusively bond to the calcium modifier cations creating clusters within the glass structure and therefore decreasing the bioactivity of fluoridated phosphate glasses, making them less suitable for biomedical applications

Design and fabrication of novel vaginal ring pessaries with improved performances

Pelvic organ prolapse (POP) is a severe gynaecological condition affecting around 50% of women over the age of 50 [1]. POP can occur due to weakening of the pelvic floor and vaginal tissue, leading to prolapse of the uterus, bladder or rectum. Pessaries are devices inserted into the vagina for treatment of POP by provision of mechanical support to the prolapsed organ, shown in Figure 1. A variety of pessaries exist, with each being suited to a particular type and stage of prolapse, one of the most common is the ring pessary [2]. Pessaries provide an alternative treatment to vaginal mesh, which has now been banned [3] following its link to multiple deaths [4]

Synthesis and electrospinning of polycaprolactone from an aluminium-based catalyst: influence of the ancillary ligand and initiators on catalytic efficiency and fibre structure

In the present study, we investigate the catalytic performance of a 2,2’-methylenebis(6- tert-butyl-4-methylphenol) (MDBP) - aluminium complex for the ring-opening polymerisation (ROP) of ε-caprolactone in combination with various alcohols as initiators. Three different alcohols are investigated, 1-adamantanemethanol (A), 1H,1H,2H,2H-perfluoro-1-octanol (F) and isopropanol (I). Samplings of polycaprolactone (PCL) at various reaction times show a linear increase of polymer molecular weight with time, with very narrow polydispersity, confirming the living nature of the catalytic system. Scanning electron microscope (SEM) images of electrospun PCL fibre mats produced from 30 wt% dichloromethane/dimethyl sulfoxide solutions show a high level of surface porosity with reasonable homogeneity of fibre diameters. Values of liquid absorption and water contact angle have been measured for the electrospun mats, with the F-capped PCL consistently showing absorption values up to three times higher than those of PCL samples capped with the other two alcohols, and increased hydrophobicity. The nature of the alcohol can influence the surface hydrophobicity and absorption ability of the electrospun fibres, demonstrating the possibility of tailoring material properties through controlled polymerisation

Influence of topography of nanofibrous scaffolds on functionality of engineered neural tissue

Properly engineered scaffolds combined with functional neurons can be instrumental for the effective repair of the neural tissue. In particular, it is essential to investigate how three-dimensional (3D) systems and topographical features can impact on neuronal activity to obtain engineered functional neural tissues. In this study, polyphenylene sulfone (PPSu) scaffolds constituted by randomly distributed or aligned electrospun nanofibers were fabricated to evaluate the neural activity in 3D culture environments for the first time. The obtained results demonstrated that the nanofibers can successfully support the adhesion and growth of neural stem cells (NSCs) and enhance neuronal differentiation compared to 2D substrates. In addition, NSCs could spread and migrate along the aligned fibers. The percentage of active NSC-derived neurons and the overall network activity in the fibrous substrates were also remarkably enhanced. Finally, the data of neuronal activity showed not only that the neurons cultured on the nanofibers are part of a functional network, but also that their activity increases, and the direction of neural signals can be controlled in the aligned 3D scaffolds

Spatially controlled proliferation, migration and differentiation of neural stem cells on novel 3D conductive scaffolds [Abstract]

Spatially controlled proliferation, migration and differentiation of neural stem cells on novel 3D conductive scaffolds [Abstract