Synthesis and characterization of star-shaped (PCL-B-PEG) as potential electrospun microfibres

Star-shaped polymers have vast potential in application due to their architecture. In this study, a 6-arm star-shaped of poly(ԑ-caprolactone)-b-poly(ethylene glycol), (6PCG) was synthesized via ring opening polymerization, (ROP) of ԑ-caprolactone and Steiglich esterification (coupling reaction) to attach the PEG arm to the star-shaped polymer with discrete core of dipentaerythritol. The polymer chemical structure was characterized by FT-IR. The molecular weight (Mn) determined from 1H NMR spectra showed that the star polymer has approximately the same molecular weight as the theoretical value. The polydispersity index indices (PDI) (>1.5) from GPC were narrow suggesting controlled polymerization reaction. Thermal stability of the star-shaped 6PCG were examined using thermogravimetric analysis, (TGA) and differential scanning calorimetry, (DSC) and showed slight increase compared to homopolymer star PCL due to the changes of end-group functionalities. Six-arm star-shaped PCL-b-PEG was dissolved in chloroform/methanol solvents and the resulting solution was used for electrospinning process. The morphology of nanofibres showed fine fibres without beads and thus a possible potential for several applications

Additive electrospraying for scaffold functionalization

In the last decade, micro- and nanostructured platforms with interesting features as bioactive carriers have been fabricated by the deposition of electrospun fibers exhibiting extended surface area and high molecular permeability associated with fully interconnected pore architecture, thus creating the opportunity to incorporate a wide range of actives/drugs for different use. In these systems, molecular release may occur via various molecular transport pathways, namely diffusion, desorption, and scaffold degradation, which may be tuned through a careful control of fiber morphology and composition. Recent studies have demonstrated that several shortcomings involve the possibility to incorporate bioactive species, not exposing molecules to fast and/or uncontrolled denaturation, thus preserving biochemical and biological fiber functionalities. In this context, additive electrospraying, namely the integration of electrosprayed nanoparticles into electrospun fiber network, is emerging as a really interesting route to control “separately” release and functional properties of the scaffolds in order to support cell activities by independent cues, during the tissue formation. Herein, we propose an overview of current progresses in the use of electrospraying and/or electrospinning for tissue engineering and molecular release. Our main objective is oriented to identify the most innovative integrated approaches recently optimized for scaffold functionalization to molecularly encode multicomponent platforms in order to obtain a spatial and time controlled release

Fabrication and characterisation of recycled polyethylene terephthalate/graphene oxide nanofibres as a potential adsorbent for methylene blue

Polymeric nanofibres can be good dye adsorbents as they have large surface areas, good connectivity, and tunable wettability. In this study, recycled polyethylene terephthalate (rPET) nanofibres loaded with graphene oxide (GO) in various amounts (0 - 1.5 v/v%) were fabricated using the electrospinning technique. GO is a carbonaceous material that exhibits a large specific area and contains an oxygenous functional group that significantly enhances the performance of electrospun nanofibres. Scanning electron microscopy images showed that rPET/GO had smooth fibres with diameters as low as 118 ± 56 nm. Fourier-Transform Infrared Spectroscopy (FTIR) confirmed GO had been well incorporated in the rPET nanofibres. The use of GO as a filler increased the tensile strength to 32.84 ± 0.33 MPa, and thus enhanced the mechanical properties of the polymeric nanofibres. The adsorption capacity of the rPET/GO nanofibres for methylene blue (MB) was evaluated, and rPET nanofibres loaded with GO showed better adsorption compared with pure rPET nanofibres. From this study, rPET/GO nanofibres show good potential as adsorbents for the treatment of dyes in wastewater

Synthesis of four arms star polymer for hydrogel formulation

Star-shaped polymer can be described as macromolecules with multi-armed polymeric material with a huge potential in biomedical applications. This study investigated the effect of molecular architecture of amphiphilic star polymers in drug formulation for wound healing application. Four arms star-shaped block copolymers constructed of polyethylene glycol (PEG) as hydrophilic block and polycaprolactone (PCL) as hydrophobic block were synthesized via combination of Steglich Reaction and ring opening polymerization (ROP). 1H NMR and FTIR analysis shows that the four star-shaped polymers is successfully synthesized. XRD analysis of the polymers shows that PEG decrease the crystallinity of the polymers. Thermal analysis (XRD and DSC) shows the thermal stability difference between homopolymer star and block copolymer star in which modification of end-group affect their thermal stability. The polydispersity index (PDI) indices from GPC were narrow suggesting controlled polymerization reaction. Preparation of hydrogel formulation shows the presence of PEG in the polymers increase the hydrophilicity and solubility in water. Drug loading of the formulation with Ciprofloxacin as drug cargo indicating high entrapment efficiency of the drug towards star-shaped polymer formulation

PCL/gelatin/graphene oxide electrospun nanofibers: effect of surface functionalization on in vitro and antibacterial response

The emergence of resistance to pathogenic bacteria has resulted from the misuse of antibiotics used in wound treatment. Therefore, nanomaterial-based agents can be used to overcome these limitations. In this study, polycaprolactone (PCL)/gelatin/graphene oxide electrospun nanofibers (PGO) are functionalized via plasma treatment with the monomeric groups diallylamine (PGO-M1), acrylic acid (PGO-M2), and tert-butyl acrylate (PGO-M3) to enhance the action against bacteria cells. The surface functionalization influences the morphology, surface wettability, mechanical properties, and thermal stability of PGO nanofibers. PGO-M1 and PGO-M2 exhibit good antibacterial activity against Staphylococcus aureus and Escherichia coli, whereas PGO-M3 tends to reduce their antibacterial properties compared to PGO nanofibers. The highest proportion of dead bacteria cells is found on the surface of hydrophilic PGO-M1, whereas live cells are colonized on the surface of hydrophobic PGO-M3. Likewise, PGO-M1 shows a good interaction with L929, which is confirmed by the high levels of adhesion and proliferation with respect to the control. All the results confirm that surface functionalization can be strategically used as a tool to engineer PGO nanofibers with controlled antibacterial properties for the fabrication of highly versatile devices suitable for different applications (e.g., health, environmental pollution)

NANOSTRUCTURED PLATFORMS WITH CONTROLLED DRUG DELIVERY FOR PERIODONTAL TISSUE REGENERATION

Electrospinning/electrospraying technique is currently represent a challenging route to produce polymer micro and nanoscaffolds with fibers and/or particles aspect. The design of integrated platforms based on the synergistic use of electrospinning and electrospraying technique offer the chance to design powerful scaffolds for tissue engineering and drug delivery applications. PCL and Chitosan are biocompatible materials to consider as ‘ideal’ candidates for cell material interation. In particular, PCL fibers may be electrospun to form submicrometric fibrous networks able to mimic the structural organization of the collagen fibres in the native ECM. Process parameters, i.e, voltage, flow rate, may be finely controlled optimize fiber size, distribution and beads occurrence. Meanwhile, chitosan particles processed by electrospraying can be successfully used as carrier of antibiotics, i.e, tetracycline for the use in periodontal surgery as confirmed by the fast release completed after 24 hours. Finally, the biological response of integrated systems was ultimately explored to validate the use of PCL/CHI scaffolds as periodontal patches

Chemical laboratory safety and management: a training module for secondary schools

This is a module used in the training programme for the science teachers in technical staff in secondary schools to promote good lab management and practices for the school communities