Short communication: Carboxylate functionalized superparamagnetic iron oxide nanoparticles (SPION) for the reduction of S. aureus growth post biofilm formation.

Biofilms formed by antibiotic resistant Staphylococcus aureus (S. aureus) continue to be a problem for medical devices. Antibiotic resistant bacteria (such as S. aureus) often complicate the treatment and healing of the patient, yet, medical devices are needed to heal such patients. Therefore, methods to treat these Biofilms once formed on medical devices are badly needed. Due to their small size and magnetic properties, superparamagnetic iron oxide nanoparticles (SPION) may be one possible material to penetrate Biofilms and kill or slow the growth of bacteria. In this study, SPION were functionalized with amine, carboxylate, and isocyanate functional groups to further improve their efficacy to disrupt the growth of S. aureus Biofilms. Without the use of antibiotics, results showed that SPION functionalized with carboxylate groups (followed by isocyanate then amine functional groups then unfunctionalized SPION) significantly disrupted Biofilms and retarded the growth of S. aureus compared to untreated Biofilms (by over 35% after 24 hours).

Superparamagnetic iron oxide nanoparticles (SPION) for the treatment of antibiotic-resistant biofilms.

Bacterial infections caused by antibiotic-resistant strains are of deep concern due to an increasing prevalence, and are a major cause of morbidity in the United States of America. In particular, medical device failures, and thus human lives, are greatly impacted by infections, where the treatments required are further complicated by the tendency of pathogenic bacteria, such as Staphylococcus aureus, to produce antibiotic resistant biofilms. In this study, a panel of relevant antibiotics used clinically including penicillin, oxacillin, gentamicin, streptomycin, and vancomycin are tested, and although antibiotics are effective against free-floating planktonic S. aureus, either no change in biofilm function is observed, or, more frequently, biofilm function is enhanced. As an alternative, superparamagnetic iron oxide nanoparticles (SPION) are synthesized through a two-step process with dimercaptosuccinic acid as a chelator, followed by the conjugation of metals including iron, zinc, and silver; thus, the antibacterial properties of the metals are coupled to the superparamagnetic properties of SPION. SPION might be the ideal antibacterial treatment, with a superior ability to decrease multiple bacterial functions, target infections in a magnetic field, and had activity better than antibiotics or metal salts alone, as is required for the treatment of medical device infections for which no treatment exists today.