Antimicrobial Polymeric Composites with Embedded Nanotextured Magnesium Oxide

Nemanja Aničić,Danilo Suvorov,Samo Jeverica,Marija Vukomanović,Mario Kurtjak

doi:10.3390/polym13132183

Nemanja Aničić, Danilo Suvorov + Show 3 more

Open Access

https://doi.org/10.3390/polym13132183

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Abstract

Nanotextured magnesium oxide (MgO) can exhibit both antibacterial and tissue regeneration activity, which makes it very useful for implant protection. To successfully combine these two properties, MgO needs to be processed within an appropriate carrier system that can keep MgO surface available for interactions with cells, slow down the conversion of MgO to the less active hydroxide and control MgO solubility. Here we present new composites with nanotextured MgO microrods embedded in different biodegradable polymer matrixes: poly-lactide-co-glycolide (PLGA), poly-lactide (PLA) and polycaprolactone (PCL). Relative to their hydrophilicity, polarity and degradability, the matrices were able to affect and control the structural and functional properties of the resulting composites in different manners. We found PLGA matrix the most effective in performing this task. The application of the nanotextured 1D morphology and the appropriate balancing of MgO/PLGA interphase interactions with optimal polymer degradation kinetics resulted in superior bactericidal activity of the composites against either planktonic E. coli or sessile S. epidermidis, S. aureus (multidrug resistant-MRSA) and three clinical strains isolated from implant-associated infections (S. aureus, E. coli and P. aeruginosa), while ensuring controllable release of magnesium ions and showing no harmful effects on red blood cells.

Highlights

Magnesium exhibits an essential role in bone mineralization, and its deficiency is a risk factor for osteoporosis [1,2]
The application of the nanotextured 1D morphology and the appropriate balancing of magnesium oxide (MgO)/PLGA interphase interactions with optimal polymer degradation kinetics resulted in superior bactericidal activity of the composites against either planktonic E. coli or sessile S. epidermidis, S. aureus and three clinical strains isolated from implant-associated infections (S. aureus, E. coli and P. aeruginosa), while ensuring controllable release of magnesium ions and showing no harmful effects on red blood cells
The metabolic activity of bacteria was measured using resazurin fluorescence assay [21] for S. epidermidis (NCIMB 8853), S. aureus (ATCC 43300-multidrug resistant S. aureus (MRSA)) and three clinical strains isolated from implant-associated infections, S. aureus (16/4856), E. coli (16/7613) and P. aeruginosa (14/8011), which colonized either the PLGA or MgO/polymer coatings’ surfaces

Summary

Introduction

Magnesium exhibits an essential role in bone mineralization, and its deficiency is a risk factor for osteoporosis [1,2]. It promotes proliferation and differentiation of osteoblasts and inhibits osteoclastogenesis [3]. To Ca2+, Mg2+ ions activate integrins for ligand binding and positively influence attachment and migration of osteoblasts [4,5]. For these reasons Mg2+ ions have been incorporated into various ceramic-based platforms for orthopaedic biomaterials to improve their bioactivity and body integration [6,7]. The improved activity is attributed to better contact with bacteria and better resistance to hydrolysis in the case of nanotextured MgO MRs [9,12]

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