Optimization of Polydopamine Coatings onto Poly-ε-Caprolactone Electrospun Fibers for the Fabrication of Bio-Electroconductive Interfaces

Abstract

In recent years, mussel adhesive proteins have attracted much attention because they can form strong adhesive interface interactions with various substrates in a wet environment. Inspired by their catechol- and amine-based molecular structure, polydopamine (PDA), a dopamine derived synthetic eumelanin polymer, was recognized as a suitable bio-interface coating. PDA was successfully used to improve adhesion due to the availability of copious functional groups for covalently immobilizing biomolecules and anchoring reactive species and ions. Recently, it has been demonstrated that PDA and its derivatives can be successfully used for the surface modification of implants interfaces to modulate in vitro cellular responses in order to enhance the in vivo functionality of biomedical implants (i.e., prosthesis). Herein, we propose the development of multifunctional scaffolds based on polyε-caprolactone (PCL) electrospun fibers coated with PDA via electro fluid dynamic methods, by optimizing polymerization/oxidation reactions capable of driving PDA self-assembly, and, ultimately, investigating the effects on cell response. Morphological analyses have confirmed the possibility to obtain different surface topographies as a function of the coating process while in vitro studies proved the ability of PDA coating to interact with cells no compromising in vitro viability. In perspective, in vitro conductive properties of fibers will be further investigated in order to validate their promising use as bioconductive interfaces for tissue engineering applications.

Keywords: electrical conductivity; electrospun fibers; in vitro response; polycaprolactone; polydopamine.

Figure 1

Scheme of the production process: polyε–caprolactone (PCL) fibers were fabricated by the electrospinning and treated in NaOH solution. Polydopamine PDA coating was successively deposited by electrospray of dopamine precursor solution.

Figure 2

Scanning electron microscope (SEM) images of (a) PCL electrospun fibers, (b) NaOH-treated, (c) PDA-coated NaOH-treated PCL fibers and (d) PDA-coated untreated PCL fibers.

Figure 3

ATR–IR spectra of PCL electrospun fibers: untreated (black curve), NaOH-treated (red curve) and PDA-coated (blue curve), and PDA-coated untreated PCL fibers (green curve).

Figure 4

(a) TGA and DSC (b) curves of PCL fibers: untreated (black curve), NaOH treated (red curve) and post PDA coating (blue curve).

Figure 5

(A) Cell adhesion of hMSC onto treated PCL fibers (* significant difference against untreated PCL fiber; p < 0.05). (B) Cell viability of hMSCs with CCK–8 assay. (* refers to significant difference against untreated PCL fibers; # refers to significant difference against NaOH treated PCL fibers).