Cationic Polymer-Coated Magnetic Nanoparticles with Antibacterial Properties: Synthesis and In Vitro Characterization

May carriers at nanoscale improve the Endodontic's future?

Nanocarriers (NCs) are dynamic nanovehicles used to transport bioactive derivatives like therapeutical formulations, drugs and/or dyes. The current review assists in understanding the mechanism of action of several recent developed NCs with antimicrobial purposes. Here, nine NCs varieties are portrayed with focus on nineteen approaches that are fulfil described based on outcomes obtained from in vitro antimicrobial assays. All approaches have previously been verified and we underline the biochemical challenges of all NCs, expecting that the present data may encourage the application of NCs in endodontic antimicrobial basic research. Methodological limitations and the evident base gaps made not possible to draw a definite conclusion about the best NCs for achieving efficient antimicrobial outcomes in endodontic studies. Due to the lack of pre-clinical trials and the scarce number of clinical trials in this emergent area, there is still much room for improvement on several fronts.

Methacrylate Cationic Nanoparticles Activity against Different Gram-Positive Bacteria

Nanotechnology is a developing field that has boomed in recent years due to the multiple qualities of nanoparticles (NPs), one of which is their antimicrobial capacity. We propose that NPs anchored with 2-(dimethylamino)ethyl methacrylate (DMAEMA) have antibacterial properties and could constitute an alternative tool in this field. To this end, the antimicrobial effects of three quaternised NPs anchored with DMAEMA were studied. These NPs were later copolymerized using different methylmethacrylate (MMA) concentrations to evaluate their role in the antibacterial activity shown by NPs. Clinical strains of Staphylococcus aureus, S. epidermidis, S. lugdunensis and Enterococcus faecalis were used to assess antibacterial activity. The minimal inhibitory concentration (MIC) was determined at the different concentrations of NPs to appraise antibacterial activity. The cytotoxic effects of the NPs anchored with DMAEMA were determined in NIH3T3 mouse fibroblast cultures by MTT assays. All the employed NPs were effective against the studied bacterial strains, although increasing concentrations of the MMA added during the synthesis process diminished these effects without altering toxicity in cell cultures. To conclude, more studies with other copolymers are necessary to improve the antibacterial effects of NPs anchored with DMAEMA.

A drug-free strategy to combat bacterial infections with magnetic nanoparticles biosynthesized in bacterial pathogens

The extensive and indiscriminate use of antibiotics in the ongoing COVID-19 pandemic might significantly contribute to the growing number of multiple drug resistant (MDR) bacteria. With the dwindling pipeline of new and effective antibiotics, we might soon end up in a post-antibiotic era, in which even common bacterial infections would be a challenge to control. To prevent this, an antibiotic-free strategy would be highly desirable. Magnetic nanoparticle (MNP)-mediated hyperthermia-induced antimicrobial therapy is an attractive option as it is considered safe for human use. Given that iron and zinc are critical for bacterial virulence, we evaluated the response of multiple pathogenic bacteria to these elements. Treatment with 1 mM iron and zinc precursors resulted in the intracellular biosynthesis of MNPs in multiple Gram-positive and Gram-negative disease-causing bacteria. The superparamagnetic nanoparticles in the treated bacteria/biofilms, generated heat upon exposure to an alternating magnetic field (AMF), which resulted in an increase in the temperature (5-6 °C) of the milieu with a subsequent decrease in bacterial viability. Furthermore, we observed for the first time that virulent bacteria derived from infected samples harbour MNPs, suggesting that the bacteria had biosynthesised the MNPs using the metal ions acquired from the host. AMF treatment of the bacterial isolates from the infected specimens resulted in a strong reduction in viability (3-4 logs) as compared to vancomycin/ciprofloxacin treatment. The therapeutic efficacy of the MNPs to induce bacterial death with AMF alone was confirmed ex vivo using infected tissues. Our proposed antibiotic-free approach for killing bacteria using intracellular MNPs is likely to evolve as a promising strategy to combat a wide range of bacterial infections.