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.

The electrophoretic deposition process (EPD) was utilized to produce bioactive hydroxyapatite/chitosan (HAP/CS) and hydroxyapatite/chitosan/gentamicin (HAP/CS/Gent) coatings on titanium. The bioactivity of newly synthesized composite coatings was investigated in the simulated body fluid (SBF) and examined by X-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy. The obtained results revealed carbonate-substituted hydroxyapatite after immersion in SBF, emphasizing the similarity of the biomimetically grown HAP with the naturally occurring apatite in the bone. The formation of biomimetic HAP was confirmed by electrochemical impedance spectroscopy and polarization measurements, through the decrease in corrosion current density and coating capacitance values after 28-day immersion in SBF. The osseointegration ability was further validated by measuring the alkaline phosphatase activity (ALP) indicating the favorable osseopromotive properties of deposited coatings (significant increase in ALP levels for both HAP/CS (3.206 U mL–1) and HAP/CS/Gent (4.039 U mL–1) coatings, compared to the control (0.900 U mL–1)). Drug-release kinetics was investigated in deionized water at 37 °C by high-performance liquid chromatography coupled with mass spectrometry. Release profiles revealed the beneficial “burst-release effect” (∼21% of gentamicin released in the first 48 h) as a potentially promising solution against the biofilm formation in the initial period. When tested against human and mice fibroblast cells (MRC-5 and L929), both composite coatings showed a noncytotoxic effect (viability >85%), providing a promising basis for further medical application trials.

Electrophoretic deposition process (EPD) was successfully used for obtaining graphene (Gr)‐reinforced composite coating based on hydroxyapatite (HAP), chitosan (CS), and antibiotic gentamicin (Gent), from aqueous suspension. The deposition process was performed as a single step process at a constant voltage (5 V, deposition time 12 min) on pure titanium foils. The influence of graphene was examined through detailed physicochemical and biological characterization. Fourier transform infrared spectroscopy, field emission scanning electron microscopy, thermogravimetric analysis, X‐ray diffraction, Raman, and X‐ray photoelectron analyses confirmed the formation of composite HAP/CS/Gr and HAP/CS/Gr/Gent coatings on Ti. Obtained coatings had porous, uniform, fracture‐free surfaces, suggesting strong interfacial interaction between HAP, CS, and Gr. Large specific area of graphene enabled strong bonding with chitosan, acting as nanofiller throughout the polymer matrix. Gentamicin addition strongly improved the antibacterial activity of HAP/CS/Gr/Gent coating that was confirmed by antibacterial activity kinetics in suspension and agar diffusion testing, while results indicated more pronounced antibacterial effect against Staphylococcus aureus (bactericidal, viable cells number reduction >3 logarithmic units) compared to Escherichia coli (bacteriostatic, <3 logarithmic units). MTT assay indicated low cytotoxicity (75% cell viability) against MRC‐5 and L929 (70% cell viability) tested cell lines, indicating good biocompatibility of HAP/CS/Gr/Gent coating. Therefore, electrodeposited HAP/CS/Gr/Gent coating on Ti can be considered as a prospective material for bone tissue engineering as a hard tissue implant.

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