Gentamicin-Loaded Bioactive Hydroxyapatite/Chitosan Composite Coating Electrodeposited on Titanium

Abstract

Composite coating of antibiotic gentamicin (Gent), natural polymer chitosan (CS), and hydroxyapatite (HAP) was successfully assessed by applying the electrophoretic deposition (EPD) technique. EPD was performed under optimized deposition conditions (5 V, 12 min) on pure titanium plates, to obtain HAP/CS and HAP/CS/Gent composite coatings in a single step from three-component aqueous suspension, with favorable antibacterial properties. Composite coatings were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron analysis, confirming the formation of composite HAP/CS and HAP/CS/Gent coatings on the titanium surface, which is due to intermolecular hydrogen bonds. Employing the XRD technique, HAP was detected by obtaining the characteristic diffraction maximums. Good antibacterial activity of the composite coating loaded with antibiotic (HAP/CS/Gent) was confirmed against Staphylococcus aureus and Escherichia coli, pointing to the high potential for bioapplication. Introduction of gentamicin in HAP/CS/Gent coating caused very mild cytotoxicity in the tested cell lines MRC-5 and L929. MTT testing was used to evaluate cell viability, and HAP/CS was classified as noncytotoxic.

Electrophoretically deposited hydroxyapatite-based composite coatings loaded with silver and gentamicin as antibacterial agents

“…5,11,21,36 As it was reported in the literature, 41,42 carbonate-substituted apatite is known to be the main constituent of the bone mineral. After the introduction of chitosan and/or graphene in composite coatings, new bands that correspond to the skeletal vibration of Gr appeared at 1540 cm -1 for Ag/HAP/Gr 36 and HAP/Gr 5 coatings and at 1578 cm -1 for HAP/CS/Gr coating, 11 (amide I band) for HAP/CS/Gr coating 11 and at 1546 (amide II band) and 1647 cm -1 (amide I band) for HAP/CS and HAP/CS/Gent coatings, 21 confirming their incorporation in the composite coatings. The interaction of chitosan with hydroxyapatite occurred via hydrogen bonding between -OH groups of HAP and -NH 2 and -OH groups of chitosan.…”

“…1) for all investigated coatings electrodeposited on titanium (HAP, HAP/Gr, Ag/HAP, Ag/HAP/Gr, HAP/CS/Gr, HAP/ /CS and HAP/CS/Gent) revealed the characteristic bands for HAP, showing that the structure of hydroxyapatite remained preserved in composite coatings, as we have shown in our previously published papers. 5,11,21,36,40 Briefly, the FTIR spectra exhibited carbonate bands at ∼1410 and ∼1460 cm -1 indicating the presence of substituted HAP because carbonate groups (CO 3 2− ) substitute phosphate and/or hydroxyl ions in HAP lattice, leading to the format-…”

“…In the form of composite coating with HAP it improves adhesion properties to the substrate and at the same time reduces the HAP brittleness. 21 The load-bearing capacity of HAP/polymer composites can be enhanced by introducing graphene (Gr) as nanofiller. 11 Graphene is a two-dimensional structure composed of single layer sp 2 -hybridized carbon atoms, possessing unique properties such as high specific area, excellent thermal and mechanical characteristics and favorable electrical conductivity, that can affect the features of the host material.…”

“…5,11,36 Besides simplicity and efficacy, this technique also enables obtaining uniform, homogenous and porous composites which are very important from the bioactivity view. 37,38 Based on previously published data, 5,11,21 EPD was performed from the three-electrode arrangement, consisting of two platinum panels as counter electrodes placed parallel to Ti foil that served as a working electrode. Thus, coating deposition on both sides of the Ti substrate was enabled, ensuring the homogeneity and uniformity of composite coatings.…”

“…Thus, coating deposition on both sides of the Ti substrate was enabled, ensuring the homogeneity and uniformity of composite coatings. 21 Pure HAP 11 and HAP-based composite coatings were deposited from ethanol suspensions -HAP/Gr, 5 Ag/HAP, 39 Ag/HAP/Gr, 36 HAP/CS 11 and HAP/CS/ /Gr 11 and aqueous suspensions -HAP/CS 21 and HAP/CS/Gent. 21 Table I represents an overview of EPD operating conditions for HAP and HAP-based composite coatings on titanium substrate.…”