Electrophoretic Deposition and Characterization of Functional Coatings Based on an Antibacterial Gallium (III)-Chitosan Complex

Abstract

Despite their broad biomedical applications in orthopedics and dentistry, metallic implants are still associated with failures due to their lack of surface biofunctionality, leading to prosthesis-related microbial infections. In order to address this issue, the current study focuses on the fabrication and characterization of a novel type of antibacterial coating based on gallium (III)-chitosan (Ga (III)-CS) complex layers deposited on metallic substrates via electrophoretic deposition (EPD). Aiming for the production of homogeneous and monophasic coatings, a two step-procedure was applied: the first step involved the synthesis of the Ga (III)-CS complex, followed by EPD from suitable solutions in an acetic acid–aqueous solvent. The influence of Ga (III) concentration on the stability of the suspensions was evaluated in terms of zeta potential. Fourier transform infrared (FTIR) and energy dispersive X-ray (EDX) spectroscopic analyses indicated the chelation of CS with Ga (III) within the coatings, while scanning electron microscopy (SEM) confirmed that no additional metallic gallium deposited during EPD. Furthermore, the results demonstrated that the wettability, mechanical properties, swelling ability, and enzymatic degradation of the coatings were affected by the quantity of Ga (III) ions. Colony forming unit (CFU) tests showed a strong synergistic effect between CS and Ga (III) in inhibiting Escherichia coli strain growth compared to control CS samples. An in vitro study with MG-63 cells showed that Ga (III)-containing coatings were not toxic after 24 h of incubation.

Facile Synthesis of Gallium (III)-Chitosan Complexes as Antibacterial Biomaterial

“…The cells are well spread on the surface of the well plate even in the high concentration of Ga (III) ions, i.e., the 1:1 Ga (III)-CS complex. The same behavior was observed in a previous study of Ga(III)-CS complex coatings, in which cells were placed in direct contact with the complexes [ 27 ]. From these observations, we can conclude that the studied concentrations of Ga (III) ions in Ga (III)-CS complexes do not lead to any adverse reactions in MG-63 cells.…”

“…This behavior makes Ga a suitable candidate for complexation with CS through bonding with N and O atoms from the amino and hydroxyl groups on the polymer chain and at least one water molecule, probably forming penta- or hexacoordinative complexes similar to Fe 3+ [ 11 , 24 , 25 ]. Previous works have emphasized the application of gallium-chitosan complexes for intertumoral radiotherapy [ 26 ] or orthopedic implant coatings [ 27 ]. Nevertheless, no systematic studies on the synthesis approach, as well as the structural, physical, and biological characterization of the raw complex material have been reported.…”

“…In this work, we present for the first time a versatile and reproducible way to synthesize Ga (III)-CS complexes with intrinsic antibacterial properties and suitable biocompatibility. We anticipate that the promising results of this study will encourage in future the implementation of Ga (III)-CS complex in biomedical devices, such as functional coatings for implants [ 27 ], wound dressing, or as tissue engineering scaffolds.…”

Advancement of Gallium and Gallium-Based Compounds as Antimicrobial Agents

“…Considering the excellent synergistic antibacterial effects of traditional antibiotics and gallium ions, combined antibacterial treatments with gallium and non-antibiotic antibacterial agents has also been explored. Akhtar et al (2020) prepared a galliumchitosan complex and performed in vitro experiments that showed that the antibacterial rate of the complex against E. coli was above 90% compared with that of single chitosan. Qiao et al (2021b) developed a triple combination strategy, as follows: 1) cationic guanidine moieties and short alkyl quaternary ammonium salts were chosen to destroy the bacterial membrane, 2) deferoxamine (DFO)-gallium conjugated to the above copolymer (namely the pGQ-DG complex) was used to disrupt iron metabolism, and 3) vancomycin (VAN) was finally added.…”

Gallium containing bioactive materials: A review of anticancer, antibacterial, and osteogenic properties

“…Ga 3+ ions have been also homogeneously embedded in chitosan via an in-situ precipitation method utilizing the chelation ability of chitosan [ 154 , 155 ]. The complex was then coated on a stainless-steel substrate by electrophoretic deposition (EPD).…”