Electrospun Nanofibers in Drug Delivery
The aim of designing an electrospun NFs in drug delivery system is to control drug release over a definite period depending on medical conditions [79]. The rate of drug release can be tailored on the basis of fiber diameter, porosity, and drug-binding mechanisms for various applications. To date, a large number of small and biomolecules, including genes, proteins, and enzymes, have been successfully incorporated into electrospun NFs, mainly by two approaches: blending electrospinning and coaxial electrospinning.
Compared with blended NFs, the coaxial NFs reduce initial burst release with a longer release period. PLCL NFs containing tetracycline hydrochloride (TCH) may be fabricated by two methods, i.e., blending and coaxial electrospinning. TCH from both types of NFs exhibits differences in burst release. For the blended NFs, 60—80% of loaded TCH is released within the first 5 h, whereas in the case of coaxial electrospun NFs, burst release is reduced to only 5—10% followed by stable and sustained release [63,72,80].
In another study, bovine serum albumin (BSA) is selected as a model protein and incorporated into PCL NFs by blending and coaxial electrospinning [81]. Similarly, coaxial NFs have exhibited more sustained release profiles compared with blended nanofibers. Moreover, addition of PEG into PCL NFs can be preserved up to 5% of the initial biological activity of the protein. Another approach of electrospun nanofiber involves the release of multiple drugs without changing the release kinetics of any agent. To study the release of multiple drugs, a composite drug delivery system consisting of NF/particle electrospun is currently indicated. Various particles such as PLGA nanoparticles and alginate and chitosan microspheres have been successfully incorporated into electrospun NFs. This strategy may improvise the combination of both hydrophobic and hydrophilic drugs. For instance, Xu et al. have encapsulated a hydrophilic protein molecule BSA into chitosan microspheres and another hydrophobic model drug benzoin in PLLA solution [82].
Electrospinning may allow the fabrication of PLLA fiber/chitosan microsphere composites to investigate dual release of these two drugs. Chitosan microspheres are dispersed uniformly in the NFs. Additionally, hydrophilic BSA shows a short-term release, whereas hydrophobic benzoin generates relatively longer and sustained release. The mesoporous silica nanoparticles have also been incorporated into electrospun NFs to investigate the dual drug release system. A choice of mesoporous silica nanoparticles is based on large specific surface area, mesoporous structure, and surface fictionalization. This technology is emerging as a promising delivery system. These studies have confirmed that a composite approach of nanofiber/particle enables the sustained and independent release of multiple drugs [63].
