# Next-generation polydopamine nanocoatings advancing the understanding of surface properties and antimicrobial efficacy

## TL;DR

This study shows that combining polydopamine with zwitterionic nanoparticles improves antibacterial properties of titanium implants without harming cell compatibility.

## Contribution

The novel use of PDA combined with poly (MBAAm-co-SBMA) zwitterionic nanoparticles enhances antibacterial efficacy on titanium surfaces.

## Key findings

- PDA + poly (MBAAm-co-SBMA) coatings showed significantly reduced S. mutans colony counts compared to PDA alone.
- Surface morphology and elemental composition were confirmed using FESEM, AFM, and EDS.
- Cytocompatibility remained favorable in both PDA and PDA + poly (MBAAm-co-SBMA) groups.

## Abstract

Biofilm formation and bacterial colonization on titanium implants pose significant challenges in healthcare, often leading to implant failure. Surface modifications using nanotechnology offer a promising approach to improve antibacterial properties while maintaining biocompatibility. To evaluate the surface characteristics, cytocompatibility, and antibacterial efficacy of titanium discs coated with polydopamine (PDA) alone versus PDA combined with poly (MBAAm-co-SBMA) zwitterionic nanoparticles. This in vitro comparative study involved the coating of titanium discs into two groups: Group 1 (PDA-coated) and Group 2 (PDA + poly (MBAAm-co-SBMA) zwitterionic nanoparticle-coated). poly (MBAAm-co-SBMA) zwitterionic nanoparticles were synthesized using the distillation–precipitation polymerization method. Surface morphology and Surface Roughness was analyzed using field emission scanning electron microscopy (FESEM) and Atomic force Microscopy (AFM), and elemental composition was determined via energy-dispersive spectroscopy (EDS). Cell viability was assessed using BCA protein assay in, while antibacterial activity against Streptococcus mutans was evaluated using the disk diffusion method. Statistical analysis was conducted using one-way ANOVA with a post-hoc Tukey test (p < 0.05), and results were reported as mean ± standard deviation . FESEM revealed uniform nanoparticle deposition with globular morphology PDA + poly (MBAAm-co-SBMA) zwitter ion nanoparticles. EDS confirmed increased carbon presence in the zwitterion-coated group. Cell viability was comparable between PDA (49.1%) and PDA + poly (MBAAm-co-SBMA) zwitterion (52.5%) groups. PDA + poly (MBAAm-co-SBMA) zwitterion group showed a significantly reduced S. mutans colony count (1.25 × 10⁴ CFU/mL) versus Group 1 (1.4 × 10⁵ CFU/mL). Conclusion Even though Polydopamine has significant antibacterial activity as evidenced in literature, it was observed in this study that, PDA-poly (MBAAm-co-SBMA) zwitterionic nanoparticle coatings demonstrated superior antibacterial activity and favourable surface morphology than PDA, without compromising cytocompatibility, making them suitable for reducing biofilm-associated infections on titanium implants.