Antibacterial and antibiofilm activities of selenium nanoparticles-antibiotic conjugates against anti-multidrug-resistant bacteria.

The crucial demand to overcome the issue of multidrug resistance is required to refine the performance of antibiotics. Such a process can be achieved by fastening them to compatible nanoparticles to obtain effective pharmaceuticals at a low concentration. Thus, selenium nanoparticles (Se NPs) are considered biocompatible agents that are applied to prevent infections resulting from bacterial resistance to multi-antibiotics. The current evaluated the effectiveness of Se NPs and their conjugates with antibiotics such as amikacin (AK), levofloxacin (LEV), and piperacillin (PIP) against Pseudomonas aeruginosa (P. aeruginosa). In addition, the study determined the antibacterial and antibiofilm properties of Se NPs and their conjugates with LEV against urinary tract pathogens such as Staphylococcus aureus (S. aureus), Enterococcus faecalis (E. faecalis), P. aeruginosa, and Escherichia coli (E. coli). The result of minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) for eight isolates of P. aeruginosa revealed that the conjugation of Se NPs with AK, LEV, and PIP resulted in a reduction in the concentration of antibiotic-conjugated Se NPs. The concentration was found to be about 10-20 times lower than that of bare antibiotics. The MIC of the Se NPs with LEV (i.e., Se NPs:LEV) for S. aureus, E. faecalis, P. aeruginosa, and E. coli was found to be 1.4:0.5, 0.7:0.25, 22:8, and 11:4 µg/mL, respectively. The results of the half-maximal inhibitory concentration (IC50) demonstrated that Se NPs:LEV conjugate have inhibited 50 % of the mature biofilms of S. aureus, E. faecalis, P. aeruginosa, and E. coli at a concentration of 27.5 ± 10.5, 18.8 ± 3.1, 40.6 ± 10.7, and 21.6 ± 3.3 µg/mL, respectively compared to the control. It has been suggested that the antibiotic-conjugated Se NPs have great potential for biomedical applications. The conjugation of Se NPs with AK, LEV, and PIP increases the antibacterial potency against resistant pathogens at a low concentration.

Enhanced antimicrobial effect of berberine in nanogel carriers with cationic surface functionality.

We report a strong enhancement in the antimicrobial action of berberine encapsulated into polyacrylic acid-based nanogels followed by further surface functionalisation with a cationic polyelectrolyte (PDAC). Due to the highly developed surface area, the nanogel carrier amplifies the contact of berberine with microbial cells and increases its antimicrobial efficiency. We show that such cationic nanogel carriers of berberine can adhere directly to the cell membranes and maintain a very high concentration of berberine directly on the cell surface. We demonstrated that the antimicrobial action of the PDAC-coated nanogel loaded with berberine on E. coli and C. reinhardtii is much higher than that of the equivalent solution of free berberine due to the electrostatic adhesion between the positively charged nanogel particles and the cell membranes. Our results also showed a marked increase in their antimicrobial action at shorter incubation times compared to the non-coated nanogel particles loaded with berberine under the same conditions. We attribute this boost in the antimicrobial effect of these cationic nanocarriers to their accumulation on the cell membranes which sustains a high concentration of released berberine causing cell death within much shorter incubation times. This study can provide a blueprint for boosting the action of other cationic antimicrobial agents by encapsulating them into nanogel carriers functionalised with a cationic surface layer. This nanotechnology-based approach could lead to the development of more effective wound dressings, disinfecting agents, antimicrobial surfaces, and antiseptic and antialgal/antibiofouling formulations.