Construction of an HBPL antibacterial coating on a phase-transition lysozyme-modified titanium surface

Abstract

Background: In the field of dental implantation, titanium and its alloys serve as primary materials for implants due to their excellent biocompatibility. However, their insufficient antibacterial properties remain a critical limitation. Bacterial adhesion and subsequent biofilm formation on titanium alloy implant surfaces can trigger peri-implant inflammation, potentially leading to severe complications such as implant failure. To address this challenge, we developed a novel surface modification strategy that endows implants with dual functionality of antibacterial activity and enhanced cellular adhesion, thereby proposing a new approach for preventing and managing peri-implantitis.

Methods: A layer-by-layer (LbL) self-assembly technique was employed to construct polyelectrolyte coatings composed of hyperbranched polylysine (HBPL) and hyaluronic acid (HA) on phase-transitioned lysozyme (PTL)-modified titanium surfaces. The surface characteristics were systematically investigated through scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). Antibacterial efficacy was evaluated by monitoring bacterial viability and morphological alterations. Cytocompatibility assessments and molecular biological investigations were conducted to examine cellular responses and osteogenesis-related gene expression.

Results: A novel polyelectrolyte coating with favorable biocompatibility and antibacterial properties was successfully fabricated on PTL-modified titanium surfaces. This coating demonstrated significant antimicrobial effects while concurrently promoting osteogenic differentiation to a certain extent.

Conclusion: This study presents a dual-functional implant surface coating with combined antibacterial and osteogenic-enhancing capabilities. The developed strategy provides new insights for clinical surface modification of dental implants and offers a promising solution for peri-implantitis prevention and treatment.

Keywords: chitosan; hyaluronic acid; hyperbranched poly-L-lysine; implant; phase-transited lysozyme; surface modified.

Figure 1

(a) Zeta potential values of two polyelectrolytes. (b) Congo red staining of titanium discs modified with phase-transitioned lysozyme (PTL). (c) Schematic illustration of layer-by-layer (LbL) assembly process for HA/HBPL coating fabrication on PTL-modified titanium. (d) Macroscopic photographs of titanium substrates after sequential surface modifications. (e) Field-emission scanning electron microscopy (FE-SEM) images of modified specimens post self-assembly.

Figure 2

(a) EDS elemental mapping of specimens at different modification stages and after self-assembly. (b) XPS survey spectra of specimens at different modification stages and after self-assembly.

Figure 3

(a) AFM images of different material surfaces. (b) AFM image showing the thickness of HA/HBPL₃ coating. (c) Water contact angles on various specimen surfaces. (d) Drug release profiles of polyelectrolyte-modified coatings. ****P < 0.0001.

Figure 4

(a) antibacterial performance of HA/HBPL₃ against Streptococcus gordonii and quantitative analysis results. (b) Antibacterial performance of HA/HBPL₃ against S. sanguinis and quantitative analysis results. (c) Confocal imaging comparisons of S. gordonii colonization patterns. (d) Confocal imaging comparisons of S. sanguinis colonization patterns. ns, P > 0.05; **: P < 0.01; ***: P < 0.001; ****: P < 0.0001.

Figure 5

(a) FE-SEM images of Streptococcus gordonii. (b) FE-SEM images of S. sanguinis.

Figure 6

(a) LDH activity changes. (b) ALP activity changes. (c) BMSC proliferation assessment on differently treated titanium surfaces. (d) MC3T3-E1 proliferation assessment on differently treated titanium surfaces. (e) Protein adsorption quantification. ns: P > 0.05; *: P < 0.05; **: P < 0.01; ***: P < 0.001; ****: P < 0.0001.

Figure 7

(a) macroscopic view of alizarin Red S staining. (b) Microscopic observation of Alizarin Red S-stained specimens. (c) Quantitative analysis of Alizarin Red S staining intensity. (d) Cellular responses and morphological changes at 6 h and 12 h post-treatment.

Figure 8

(a) expression of osteogenic-related genes. (b) Expression of osteogenic-related proteins. (c) Quantitative analysis of osteogenic-related protein expression. (d) H&E staining of hard tissue sections from ectopic implantation. *P < 0.05; ***P < 0.001.