Abstract
Biodegradable poly(L-lactic acid) (PLA) fibrous scaffolds were prepared by electrospinning from a PLA melt containing poly(ethylene glycol) (PEG) as a plasticizer to obtain thinner fibers. The effects of PEG on the melt electrospinning of PLA were examined in terms of the melt viscosity and fiber diameter. Among the parameters, the content of PEG had a more significant effect on the average fiber diameter and its distribution than those of the spinning temperature. Furthermore, nano-/microfibrous silk fibroin (SF)/PLA and PLA/PLA composite scaffolds were fabricated by hybrid electrospinning, which involved a combination of solution electrospinning and melt electrospinning. The SF/PLA (20/80) scaffolds consisted of a randomly oriented structure of PLA microfibers (average fiber diameter = 8.9 µm) and SF nanofibers (average fiber diameter = 820 nm). The PLA nano-/microfiber (20/80) scaffolds were found to have similar pore parameters to the PLA microfiber scaffolds. The PLA scaffolds were treated with plasma in the presence of either oxygen or ammonia gas to modify the surface of the fibers. This approach of controlling the surface properties and diameter of fibers could be useful in the design and tailoring of novel scaffolds for tissue engineering.
Highlights
Electrospinning from melt is an attractive solvent-free manufacturing process for tissue engineering scaffolds [1]
The melt electrospinning process is strongly affected by the viscosity of the polymer melt, which is strongly dependent on the temperature for thermoplastic polymers
To investigate the efficiency of the poly(ethylene glycol) (PEG) on poly(L-lactic acid) (PLA), Differential scanning calorimetry (DSC) was carried out using the PLA blends with different PEG content up to 20 wt%
Summary
Electrospinning from melt is an attractive solvent-free manufacturing process for tissue engineering scaffolds [1]. Melt electrospinning is attractive for its applicability to commodity polymers, such as polypropylene and polyethylene, which are only soluble in limited solvents and require high temperature for dissolution [2,3,4,5,6,7]. A polymer melt has higher viscosity than the solution state, which usually generates thicker micron-sized fibers than those of solution electrospinning. Important parameters reported for melt electrospinning are the molecular weight, tacticity, melting point of the polymer, electric field strength, distance from the nozzle, mass flow rate, and process temperatures (electrospinning temperature, heating chamber temperature) [9,10,11,12,13]. Dalton et al [9] employed a viscosity-reducing additive to reduce the diameter of fiber electrospun from the polymer melt. They found that the additive reduces the average chain length and reduces the viscosity of the polymer solution and, with it, the fiber diameter
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