Quantitative analysis of povidone-iodine thin films by X-ray photoelectron spectroscopy and their physicochemical properties

Preparation and characterizations of antibacterial iodine-containing coatings on pure Ti

Iodine-containing coatings were prepared on pure Ti surfaces via electrochemical deposition to enhance their antibacterial properties. The factors influencing iodine content were analyzed using an orthogonal experiment. The electrochemically deposited samples were characterized using scanning electron microscopy with energy dispersive spectroscopy and X-ray photoelectron spectroscopy, and their antibacterial properties and cytotoxicity were evaluated. The results showed that changing the deposition time is an effective way to control the iodine content. The iodine content, coating thickness, and adhesion of the samples increased with deposition time. Iodine in the coatings mainly exists in three forms, which are I2, I3-, and pentavalent iodine. For samples with iodine-containing coatings, the antibacterial ratios against E. coli and S. aureus were greater than 90% and increased with increasing iodine content. Although the samples with iodine-containing coatings showed some inhibition of the proliferation of MC3T3-E1 cells, the cell viabilities were all higher than 80%, suggesting that iodine-containing coatings are biosafe.

Multifunctional hydrogel coatings with high antimicrobial loading efficiency and pH-responsive properties for urinary catheter applications

Catheter-associated urinary tract infections are one of the most common hospital-acquired infections. Encrustation formation results from infection of urease-producing bacteria and further complicates the situation. A typical sign of the initial onset of encrustation formation is the alkalization of the urine (pH up to 9-10). However, effective antibacterial strategies with high antimicrobial loading efficiency and pH-responsiveness of antimicrobial release are still lacking. In this study, we developed a poly(sulfobetaine methacrylate)-tannic acid (polySBMA-TA) hydrogel coating, which served as a universal, efficient, and responsive carrier for antimicrobials on urinary catheters. Common antimicrobials, including poly(vinylpyrrolidone)-iodine, copper ions, and nitrofurazone were loaded into the polySBMA-TA coating in high efficiency (several fold higher than that of the polySBMA coating), via the formation of multiple non-covalent interactions between the antimicrobials and hydrogel coating. The hydrogel coatings maintained good antibacterial properties under neutral conditions. More importantly, the pH-responsive release of antibacterial agents under alkaline conditions further enhanced the antibacterial activity of the coatings, which was advantageous for killing the urease-producing bacteria and preventing encrustation. In vitro and in vivo tests confirmed that the hydrogel coating has good biocompatibility, and could effectively inhibit bacterial colonization and encrustation formation. This study offers new opportunities for the utilization of a simple and universal antimicrobial-loaded hydrogel coating with smart pH-responsive properties to combat bacterial colonization and encrustation formation in urinary catheters.

Povidone-Iodine Fails to Eradicate Chronic Suppurative Otitis Media and Demonstrates Ototoxic Risk in Mice

HYPOTHESIS

Commercially available povidone-iodine solution can eliminate biofilms and persister cells rapidly in in vivo achievable concentrations without inducing ototoxicity.

BACKGROUND

Chronic suppurative otitis media (CSOM) is a substantial global problem. Current treatment options often induce a temporary remission without leading to a permanent cessation of symptoms secondary to the treatments' inability to eliminate persister cells. Povidone-iodine has been shown to be able to clear biofilm and planktonic cells in in vitro assays, but there are reports of ototoxic effects limiting its clinical utility.

METHODS

Bacterial and biofilm growth with quantification by spectrophotomer, murine auditory brainstem response (ABR), and distortion product otoacoustic emissions, immunohistochemistry, in vivo povidone-iodine treatment of murine CSOM, persister cell assay.

RESULTS

Commercially available 10% povidone-iodine solution is able to completely eradicate multiple clinical strains of Pseudomonas aeruginosa and Staphylococcus aureus in vitro with 10 minutes of exposure. Mice that have received a transtympanic injection of 1% povidone-iodine solution did not have significantly different auditory brainstem response or distortion product otoacoustic emission results compared with the control. Mice that received a povidone-iodine scrub or 10% povidone-iodine solution had significantly worsened hearing (25- and 13-dB increase in threshold, respectively; p < 0.05). In vivo CSOM infection recurred in all mice after the completion of treatment with 10% povidone-iodine solution, and there was no improvement in the bacterial load after treatment, indicating in vivo failure of therapy.

CONCLUSION

Povidone-iodine solution is effective at eliminating biofilm and persister cells in vitro at in vivo achievable concentrations but fails in vivo most likely because of kinetics of distribution in vivo. Even if drug distribution could be improved, the therapeutic window is likely to be too small given that the diluted solution does not have ototoxic potential, whereas while the scrub variant, which contains detergents, and the undiluted solution are ototoxic after a single treatment.

Antibiofilm Properties of Antiseptic Agents Used on Pseudomonas aeruginosa Isolated from Diabetic Foot Ulcers

In diabetic foot ulcers (DFUs), biofilm formation is a major challenge that promotes wound chronicity and delays healing. Antiseptics have been proposed to combat biofilms in the management of DFUs. However, there is limited evidence on the activity of these agents against biofilms, and there are questions as to which agents have the best efficiency. Here, we evaluated the antibiofilm activity of sodium hypochlorite, polyvinylpyrrolidoneIodine (PVPI), polyhexamethylenebiguanide (PHMB) and octenidine against Pseudomonas aeruginosa strains using static and dynamic systems in a chronic-wound-like medium (CWM) that mimics the chronic wound environment. Using Antibiofilmogram®, a technology assessing the ability of antiseptics to reduce the initial phase of biofilm formation, we observed the significant activity of antiseptics against biofilm formation by P. aeruginosa (at 1:40 to 1:8 dilutions). Moreover, 1:100 to 1:3 dilutions of the different antiseptics reduced mature biofilms formed after 72 h by 10-log, although higher concentrations were needed in CWM (1:40 to 1:2). Finally, in the BioFlux200TM model, after biofilm debridement, sodium hypochlorite and PHMB were the most effective antiseptics. In conclusion, our study showed that among the four antiseptics tested, sodium hypochlorite demonstrated the best antibiofilm activity against P. aeruginosa biofilms and represents an alternative in the management of DFUs.

In-depth analysis of iodine in artificial biofilm model layers by variable excitation energy XPS and argon gas cluster ion sputtering XPS

Here, we present a study on agarose thin-film samples that represent a model system for the exopolysaccharide matrix of biofilms. Povidone-iodide (PVP-I) was selected as an antibacterial agent to evaluate our x-ray photoelectron spectroscopy (XPS)-based methodology to trace specific marker elements, here iodine, commonly found in organic matrices of antibiotics. The in-depth distribution of iodine was determined by XPS analyses with variable excitation energies and in combination with argon gas cluster ion beam sputter cycles. On mixed agarose/PVP-I nanometer-thin films, both methods were found to solve the analytical task and deliver independently comparable results. In the mixed agarose/PVP-I thin film, we found the outermost surface layer depleted in iodine, whereas the iodine is homogeneously distributed in the depth region between this outermost surface layer and the interface between the thin film and the substrate. Depletion of iodine from the uppermost surface in the thin-film samples is assumed to be caused by ultrahigh vacuum exposure resulting in a loss of molecular iodine (I₂) as reported earlier for other iodine-doped polymers.