Cecilia Zorzi Bueno

An adherent chitosan-based coating on polyethylene enables sustained moxifloxacin release and long-term antibacterial activity.

If untreated, skin wounds can lead to severe complications. Depending on the type of injury, long-term antibiotic administration is often required, and this decreases patient compliance. This limitation could be addressed by applying dressings capable of preventing infections by controlling drug release to the wound site. In this research, biodegradable wound dressings were investigated, based on natural polymers chitosan and alginate and incorporating the broad-spectrum gentamicin as antibiotic. Specifically, gentamicin was loaded into alginate nanoparticles, which were then loaded into chitosan-based films. This approach aimed at obtaining a system capable of modulating antibiotic release. The obtained nanoparticles had an average diameter of 86 nm and polydispersity index of 0.15. Antibiotic loading was around 600 µg/mg, with loading efficiency close to 100%. Films incorporating nanoparticles were compared to control films, which contained only gentamicin. Results showed that nanoparticles incorporation decreased film’s swelling in phosphate buffer saline, thus leading to a decrease in burst release while cytocompatibility for human dermal fibroblasts was maintained. Antibacterial activity was confirmed against both gram-positive and gram-negative bacteria. Moreover, the antibiotic was released as a function of pH, with distinct behavior at pHs ranging from 7.4 to 5.5. This indicates that alginate nanoparticles dispersed in chitosan films effectively release gentamicin on demand.

Sourcing and batch differences are often cited as intrinsic drawbacks for all natural polymers. Chitosan makes no exception. Chitosan is a biocompatible and biodegradable biopolymer with high potential for several biomedical applications, especially for releasing drugs and bactericidal and virucidal agents. Despite the potential of chitosan as a matrix for producing antibacterial films, the variability in its composition, stemming from its natural sources, can hinder the translation from bench to industry. To overcome this concern, we conducted a study to access the interchangeability of chitosan for the development of antibacterial drug release systems, in particular one system crosslinked with tannic acid and iron sulfate. Chitosans from different suppliers were characterized and used to synthetize films containing gentamicin, according to a previously reported protocol. The impact of molecular weight (M_W), deacetylation degree and purity on film properties and antibiotic release kinetics was assessed and results were compared. The films exhibited different initial bursts followed by similar sustained release profiles. All films exhibited antibacterial activity against both E. coli and S. aureus for at least 42 days. Moreover, films were cyto- and hemocompatible. Therefore, despite some differences in physicochemical properties, the interchangeability among the studied chitosan suppliers to produce antibacterial films is feasible, and the final product properties and performances are not significantly altered.

Background/Objectives: Medical devices are susceptible to bacterial colonization and biofilm formation, which can result in severe infections, leading to prolonged hospital stays and increased burden on society. Antibacterial films have the potential to assist in preventing biofilm formation, thereby reducing administration of antibiotics and the emergence of antibiotic-resistant strains. In a previous study, a chitosan-based matrix crosslinked with tannic acid and loaded with gentamicin was reported. In this study, five different antibiotics (moxifloxacin, ciprofloxacin, trimethoprim, sulfamethoxazole or linezolid) were loaded into these chitosan-based films, and their impact on the release behavior carefully assessed. Methods: The samples were characterized according to their thickness, swelling, and mass loss in phosphate-buffered saline (PBS), as well as by morphology using scanning electron microscopy (SEM) and optical phase contrast microscopy. Antibiotic release over time was quantified in PBS by high-performance liquid chromatography (HPLC). Antibacterial activity was investigated by disk diffusion test and antibiotic release over time. Finally, the cytotoxicity of the samples was assessed with human dermal fibroblasts. Results: The obtained results differed significantly, especially regarding the antibiotic release time and antibacterial activity, which varied from one day to six months, enabling classification of the films from burst/transient to prolonged release. The films also showed antibacterial features against bacteria mostly present in medical devices and displayed to be non-cytotoxic. Conclusions: In conclusion, it was demonstrated that the antibiotics structure significantly alters the release kinetics, and that by carefully selecting the antibiotic, the consequent release can be tuned. This approach yielded films that could be used for potentially-scalable release in antimicrobial coatings specific to medical devices, aiming to reduce biomaterial associated infections (BAIs).

A otite é uma inflamação no canal auditivo dos mamíferos, que se manifesta de forma aguda ou crônica. Os fatores que influenciam o surgimento desta doença são limpeza inadequada, imunossupressão e clima. Dependendo da região do ouvido afetada, a otite é classificada como externa, média ou interna. As espécies mais frequentemente acometidas pela doença são cães e gatos. A otite é causada por bactérias, fungos, vírus e alergias. A otite bacteriana é a mais comum e seu tratamento envolve o uso de antibióticos em diversas formas farmacêuticas, como soluções e suspensões. O uso contínuo e indiscriminado destes medicamentos pode causar resistência bacteriana, o que leva a uma busca constante de inovação em medicamentos. O presente trabalho é uma revisão bibliográfica de artigos publicados no período entre 2013 a 2024 com foco em novos medicamentos para otite, com destaque para a nanotecnologia em fase de estudos pré-clínicos. Durante esta década, avanços significativos foram alcançados. Exemplos de novas tecnologias incluem nanofibras, vesículas nanoelásticas e nanoemulsões, que oferecem melhor entrega e estabilidade dos medicamentos. As perspectivas são de que as novas gerações de medicamentos para otite utilizem a nanotecnologia.

Healthcare-associated infections (HAIs) represent a global burden, leading to significant mortality and generating financial costs. One important cause of HAIs is the microbiological contamination of implantable medical devices. In this context, a novel antimicrobial drug-eluting system, based on chitosan and loaded with gentamicin, a broad-spectrum antibiotic, was developed. The effects of the addition of tannic acid and different FeSO₄ concentrations on the loaded antibiotic release were evaluated. The properties of the films were assessed in terms of thickness, swelling, mass loss and wettability. The films’ surface composition was characterized by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The antibiotic release in phosphate buffer saline was quantified by high-performance liquid chromatography–mass spectrometry, and the antibacterial activity was evaluated. Hemolysis and cytotoxicity were also assessed. The results showed that the addition of tannic acid and iron decreased the swelling degree and degradation due to strong interactions between the different components, thus impacting gentamicin release for up to 35 days. In conclusion, this study presents a novel strategy to produce low-cost and biocompatible antimicrobial drug-eluting systems with sustained and prolonged antibacterial activity over more than a month.

L-asparaginase (ASNase) is an important biological drug used to treat Acute Lymphoblastic Leukemia (ALL). It catalyzes the hydrolysis of L-asparagine (Asn) in the bloodstream and, since ALL cells cannot synthesize Asn, protein synthesis is impaired leading to apoptosis. Despite its therapeutic importance, ASNase treatment is associated to side effects, mainly hypersensitivity and immunogenicity. Furthermore, degradation by plasma proteases and immunogenicity shortens the enzyme half-life. Encapsulation of ASNase in liposomes, nanostructures formed by the self-aggregation of phospholipids, is an attractive alternative to protect the enzyme from plasma proteases and enhance pharmacokinetics profile. In addition, PEGylation might prolong the in vivo circulation of liposomes owing to the spherical shielding conferred by the polyethylene (PEG) corona around the nanostructures. In this paper, ASNase was encapsulated in liposomal formulations composed by 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) or 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) containing or not different concentrations of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N [methoxy (polyethylene glycol)-2000] (DSPE-PEG). Nanostructures of approximately 142–202 nm of diameter and polydispersity index (PDI) of 0.069 to 0.190 were obtained and the vesicular shape confirmed by Transmission Electron Microscopy (TEM and cryo-TEM). The encapsulation efficiency (%EE) varied from 10% to 16%. All formulations presented activity in contact with ASNase substrate, indicating the liposomes permeability to Asn and/or enzyme adsorption at the nanostructures’ surface; the highest activity was observed for DMPC/DSPE-PEG 10%. Finally, we investigated the activity against the Molt 4 leukemic cell line and found a lower IC₅₀ for the DMPC/DSPE-PEG 10% formulation in comparison to the free enzyme, indicating our system could provide in vivo activity while protecting the enzyme from immune system recognition and proteases degradation.

This work reports, for the encapsulation of l-asparaginase, an anticancer enzyme into hybrid PMPC₂₅–PDPA₇₀/PEO₁₆–PBO₂₂ asymmetric polymersomes previously developed by our group, with loading capacities with over 800 molecules per vesicle. Enzyme-loaded polymersomes show permeability and capacity to hydrolyze l-asparagine, which is essential to cancer cells. The nanoreactors proposed in this work can be potentially used in further studies to develop novel therapeutic alternatives based on l-asparaginase.