Nanoporous Silica Coatings as a Drug Delivery System for Ciprofloxacin: Outcome of Variable Release Rates in the Infected Middle Ear of Rabbits

Fabrication and Evaluation of Hyaluronidase-Responsive Scaffolds by Electrospinning with Antibacterial Properties for Tympanic Membrane Repair

Tympanic membrane perforation (TMP) is prevalent in clinical settings. Patients with TMPs often suffer from infections caused by Staphylococcus aureus and Pseudomonas aeruginosa, leading to middle ear and external ear canal infections, which hinder eardrum healing. The objective of this study is to fabricate an enzyme-responsive antibacterial electrospun scaffold using poly(lactic-co-glycolic acid) and hyaluronic acid for the treatment of infected TMPs. The properties of the scaffold were characterized, including morphology, wettability, mechanical properties, degradation properties, antimicrobial properties, and biocompatibility. The results indicated that the fabricated scaffold had a core-shell structure and exhibited excellent mechanical properties, hydrophobicity, degradability, and cytocompatibility. Furthermore, in vitro bacterial tests and ex vivo investigations on eardrum infections suggested that this scaffold possesses hyaluronidase-responsive antibacterial properties. It may rapidly release antibiotics when exposed to the enzyme released by S. aureus and P. aeruginosa. These findings suggest that the scaffold has great potential for repairing TMPs with infections.

Approaches for ear-targeted delivery systems in neurosensory disorders to avoid chronic hearing loss mediated neurological diseases

BACKGROUND & OBJECTIVE

Hearing loss is a common audio-vestibular-related neurosensory disability of inner ears, in which patients exhibit clinical symptoms of dizziness, gait unsteadiness, and oscillopsia, at an initial stage. While, if such disorders are untreated for a prolonged duration then the progression of disease into a chronic state significantly decreases GABA level as well as an alteration in the neurotransmission of CNS systems. Hence, to control the progression of disease into a chronic state, timely and targeted delivery of the drug into the site of action in the ear is now attracting the interest of neurologists for effective and safe treatment of such disorders. Among delivery systems, owing to small dimension, better penetration, rate-controlled release, higher bioavailability; nanocarriers are preferred to overcome delivery barriers, improvement in residence time, and enhanced the performance of loaded drugs. Subsequently, these carriers also stabilize encapsulated drugs while the opportunity to modify the surface of carriers favors guided direction for site-specific targeting. Conventional routes of drug delivery such as oral. intravenous, and intramuscular are poorer in performance because of inadequate blood supply to the inner ear and limited penetration of blood-inner ear barrier.

CONCLUSION

This review summarized novel aspects of non-invasive and biocompatible nanoparticles-based approaches for targeted delivery of drugs into the cochlea of the ear to reduce the rate, and extent of the emergence of any hearing loss mediated neurological disorders.

Options and Limitations in Clinical Investigation of Bacterial Biofilms

Bacteria can form single- and multispecies biofilms exhibiting diverse features based upon the microbial composition of their community and microenvironment. The study of bacterial biofilm development has received great interest in the past 20 years and is motivated by the elegant complexity characteristic of these multicellular communities and their role in infectious diseases. Biofilms can thrive on virtually any surface and can be beneficial or detrimental based upon the community's interplay and the surface. Advances in the understanding of structural and functional variations and the roles that biofilms play in disease and host-pathogen interactions have been addressed through comprehensive literature searches. In this review article, a synopsis of the methodological landscape of biofilm analysis is provided, including an evaluation of the current trends in methodological research. We deem this worthwhile because a keyword-oriented bibliographical search reveals that less than 5% of the biofilm literature is devoted to methodology. In this report, we (i) summarize current methodologies for biofilm characterization, monitoring, and quantification; (ii) discuss advances in the discovery of effective imaging and sensing tools and modalities; (iii) provide an overview of tailored animal models that assess features of biofilm infections; and (iv) make recommendations defining the most appropriate methodological tools for clinical settings.

pH-responsive release of chlorhexidine from modified nanoporous silica nanoparticles for dental applications

A pH-sensitive stimulus-response system for controlled drug release was prepared by modifying nanoporous silica nanoparticles (NPSNPs) with poly(4-vinylpyridine) using a bismaleimide as linker. At physiological pH values, the polymer serves as gate keeper blocking the pore openings to prevent the release of cargo molecules. At acidic pH values as they can occur during a bacterial infection, the polymer strains become protonated and straighten up due to electrostatic repulsion. The pores are opened and the cargo is released. The drug chlorhexidine was loaded into the pores because of its excellent antibacterial properties and low tendency to form resistances. The release was performed in PBS and diluted hydrochloric acid, respectively. The results showed a considerably higher release in acidic media compared to neutral solvents. Reversibility of this pH-dependent release was established. In vitro tests proved good cytocompatibility of the prepared nanoparticles. Antibacterial activity tests with

Biocompatibility of silver containing silica films on Bioverit® II middle ear prostheses in rabbits

For several centuries silver is known for its antibacterial effects. The middle ear is an interesting new scope for silver application since chronic inflammations combined with bacterial infection cause complete destruction of the fragile ossicle chain and tympanic membrane. The resulting conductive deafness requires tympanoplasty for reconstruction. Strategies to prevent bacterial growth on middle ear prostheses are highly recommended. In this study, rabbits were implanted with Bioverit® II middle ear prostheses functionalized with silver containing dense and nanoporous silica films which were compared with pure silica coatings as well as silver sulfadiazine cream applied on nanoporous silica coating. The health status of animals was continuously monitored; blood was examined before and after implantation. After 21 days, the middle ears were inspected; implants and mucosal samples were processed for electron microscopy. Autopsies were performed and systemic spreading of silver was chemically analyzed exemplarily in liver and kidneys. For verification of direct cytotoxicity, NIH 3T3 cells were cultured on similar silver containing silica coatings on glass up to 3 days. In vitro a reduced viability of fibroblasts adhering directly on the samples was detected compared to cells growing on the surrounding plastic of the same culture dish. In transmission electron microscopy, phagocytosed silver silica fragments, silver sulfadiazine cream as well as silver nanoparticles were noticed inside endosomes. In vivo, clinical and post mortem examinations were inconspicuous. Chemical analyses showed no increased silver content compared to controls. Mucosal coverages on almost all prostheses were found. But reduction of granulation tissue was only obvious around silver-coated implants. Single necroses and apoptosis in the mucosa were correlated by intracellular accumulation of metallic silver. For confirming supportive healing effects of middle ear implants, silver ion aggregates need to be tested in the future to optimize biocompatibility while assuring bactericidal effects in the middle ear.