Antibacterial and Bioactive Surface Modifications of Titanium Implants by PCL/TiO₂ Nanocomposite Coatings

Abstract

Surface modification of biomedical implants is an established strategy to improve tissue regeneration, osseointegration and also to minimize the bacterial accumulation. In the present study, electrospun poly(ε-caprolactone)/titania (PCL/TiO₂) nanocomposite coatings were developed on commercially pure titanium (cpTi) substrates for an improved biological and antibacterial properties for bone tissue engineering. TiO₂ nanoparticles in various amounts (2, 5, and 7 wt %) were incorporated into a biodegradable PCL matrix to form a homogeneous solution. Further, PCL/TiO₂ coatings on cpTi were obtained by electrospinning of PCL/TiO₂ solution onto the substrate. The resulted coatings were structurally characterized and inspected by employing scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Given the potential biological applications of PCL/TiO₂ coated cpTi substrates, the apatite-forming capacity was examined by immersing in simulated body fluid (SBF) for upto 21 days. Biocompatibility has been evaluated through adhesion/proliferation of hFOB osteoblast cell lines and cytotoxicity by MTT assay. Antimicrobial activity of PCL/TiO₂ nanocomposites has been tested using UV light against gram-positive Staphylococcus aureus (S.aureus). The resulting surface displays good bioactive properties against osteoblast cell lines with increased viability of 40% at day 3 and superior antibacterial property against S.aureus with a significant reduction of bacteria to almost 76%. Surface modification by PCL/TiO₂ nanocomposites makes a viable approach for improving dual properties, i.e., biological and antibacterial properties on titanium implants which might be used to prevent implant-associated infections and promoting cell attachment of orthopedic devices at the same time.

Keywords: TiO2 photocatalytic; antibacterial coatings; electrospinning; nanocomposite coatings; orthopedic infections; titanium.

Figure 1

SEM Images displaying (a) cpTi substrate; PCL mat containing (b) 0 wt % TiO₂, (c) 3 wt % TiO₂, (d) 5 wt % TiO₂, and (e) 7 wt % TiO₂.

Figure 2

(a) XRD and (b) FTIR patterns of PCL/TiO₂ (2, 5 and 7 wt %) nanocomposites in comparison with pure PCL.

Figure 3

Water contact measurements on various surfaces obtained as a function of TiO₂ wt % with distinctive water droplet images after 5 s from droplet.

Figure 4

SEM images of (a) An, (b) PCL (c) PCL with 2 wt % TiO₂ (d) PCL with 5 wt % TiO₂ and (e) PCL with 7 wt % TiO₂ after immersing in SBF for 21 days. (f) EDS analysis results for the newly formed calcium and phosphate of PCL with 5 wt % TiO₂.

Figure 5

hFOB Cell viability on An, Pure PCL coated, PCL/2TiO₂ coated, PCL/5TiO₂ coated and PCL/7TiO₂ coated cpTi samples cultured for day 1 and day 3 (p < 0.05).

Figure 6

SEM images of hFOB cells seeded on various substrates after day 1, and day 3.

Figure 7

Antibacterial activity on different substrates against S.aureus.

Figure 8

Schematic illustration for the mechanism of degradation bacteria by TiO₂ nanoparticles under UV radiation and cellular activity of PCL/TiO₂ nanocomposites.