Coaxial Electrospinning of (Fluorescein Isothiocyanate-Conjugated Bovine Serum Albumin)-Encapsulated Poly(ε-caprolactone) Nanofibers for Sustained Release

Abstract

As an aim toward developing biologically mimetic and functional nanofiber-based tissue engineering scaffolds, we demonstrated the encapsulation of a model protein, fluorescein isothiocyanate-conjugated bovine serum albumin (fitcBSA), along with a water-soluble polymer, poly(ethylene glycol) (PEG), within the biodegradable poly(epsilon-caprolactone) (PCL) nanofibers using a coaxial electrospinning technique. By variation of the inner flow rates from 0.2 to 0.6 mL/h with a constant outer flow rate of 1.8 mL/h, fitcBSA loadings of 0.85-2.17 mg/g of nanofibrous membranes were prepared. Variation of flow rates also resulted in increases of fiber sizes from ca. 270 nm to 380 nm. The encapsulation of fitcBSA/PEG within PCL was subsequently characterized by laser confocal scanning microscopy, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analysis. In vitro release studies were conducted to evaluate sustained release potential of the core-sheath-structured composite nanofiber PCL-r-fitcBSA/PEG. As a negative control, composite nanofiber PCL/fitcBSA/PEG blend was prepared from a normal electrospinning method. It was found that core-sheath nanofibers PCL-r-fitcBSA/PEG pronouncedly alleviated the initial burst release for higher protein loading and gave better sustainability compared to that of PCL/fitcBSA/PEG nanofibers. The present study would provide a basis for further design and optimization of processing conditions to control the nanostructure of core-sheath composite nanofibers and ultimately achieve desired release kinetics of bioactive proteins (e.g., growth factors) for practical tissue engineering applications.

Polymeric Nanofibers in Tissue Engineering

“…[1][2][3] By collecting fibers on a rotating mandrel, rather than a flat plate, the fiber orientation can be directed. [23][24][25][26][27] Other variations include coaxial spinning, 28,29 which can create hollow tube nanofibers or fibers with an inner core composed of one material and an outer layer composed of a second material 30 that can be used to alter the chemical 31 or mechanical 31,32 properties of the fibers. Advantages of this technique include the efficiency and simplicity of the procedure, the inexpensive setup, and the ability to control many factors, such as the fiber diameter, orientation, and composition; disadvantages include the use of organic solvents and the limited control of pore structures.…”

“…A burst release will provide an initial high delivery rate and a much lower release rate over an extended period, limiting the overall time course of drug release at effective levels. 29 In the case of polymeric nanofibers, the degree of burst release varies depending on the method of loading and the steps taken to control the delivery. For example, altering the polymer composition or coating the surface of the fibers with a polymer 72 can be performed to reduce the degree of initial burst and extend the time course of release.…”

“…For example, a significant burst release is reported when using this approach alone. 29,72 Consequently, approaches have been taken to alter the release profiles. Varying the polymer composition of the fibers has been shown to alter the release profile, and in some cases significantly extend the release.…”

Eletrofiação de Polímeros em Solução: parte I: fundamentação Teórica

“…Nanotubos ou nanofibras com estrutura interna e externa diferenciada (do tipo core-shell) (Figura 2) podem ser fabricadas empregando-se capilares concêntricos conforme proposto por Zhang et al [44] . Existem três principais abordagens que podem ser empregadas na modificação do campo eletrostático [45,46] .…”

“…Em geral, a adição de um sal à solução faz com que a condutividade elétrica da solução aumente, Figura 2. Estrutura core-shell de poli(ε-caprolactona)-polietileno glicol (reimpresso com permissão de Zhang et al [44] ).…”