Alginate is a linear biodegradable polysaccharide polymer, which is bio-renewable and widely used for various biomedical applications. For the next generation of medical textiles, alginate nanofibres are desirable for their use in wound dressings that are biocompatible, sustainable, and abundantly available. This study has developed a unique manufacturing process for producing alginate nanofibres with exceptional antimicrobial properties of oregano essential oil (OEO) as a natural antimicrobial agent. OEO with varying degrees of concentration was incorporated in an aqueous alginate solution. Appropriate materials and electrospinning process parameter selection allowed us to manufacture alginate fibres with a range of diameters between 38 and 105 nm. A unique crosslinking process for alginate nanofibres using extended water soaking was developed. Mechanical characterisation using micro-mechanical testing of nonwoven electrospun alginate/oregano composite nanofibres revealed that it was durable. An extensive antimicrobial study was carried out on alginate/oregano composite nanofibres using a range of Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA) and Listeria monocytogenes) and Gram-negative bacteria (Klebsiella pneumoniae and Salmonella enterica), which are common wound and food pathogens. The results indicated that increasing the concentration of OEO from 2 to 3 wt % showed improved antimicrobial activity against all pathogens, and activity was significantly improved against MRSA compared to a non-alginate-based control disk containing OEO. Therefore, our research suggests that all-natural alginate/oregano nanofibre composite textiles offer a new generation of medical textiles for advanced wound dressing technology as well as for food packaging applications.

Human parasitic infections cause a combined global mortality rate of over one million people per annum and represent some of the most challenging diseases for medical intervention. Current chemotherapeutic strategies often require prolonged treatment, coupled with subsequent drug-induced cytotoxic morbidity to the host, while resistance generation is also a major concern. Metals have been used extensively throughout the history of medicine, with more recent applications as anticancer and antimicrobial agents. Ruthenium metallotherapeutic antiparasitic agents are highly effective at targeting a range of key parasites, including the causative agents of malaria, trypanosomiasis, leishmaniasis, amoebiasis, toxoplasmosis and other orphan diseases, while demonstrating lower cytotoxicity profiles than current treatment strategies. Generally, such compounds also demonstrate activity against multiple cellular target sites within parasites, including inhibition of enzyme function, cell membrane perturbation, and alterations to metabolic pathways, therefore reducing the opportunity for resistance generation. This review provides a comprehensive and subjective analysis of the rapidly developing area of ruthenium metal-based antiparasitic chemotherapeutics, in the context of rational drug design and potential clinical approaches to combatting human parasitic infections.

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Background Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that is highly resistant to antibiotics and biocidal products used in both medical and industrial environments respectively. Metal-based compounds have been used as antimicrobial agents throughout history for a broad range of applications. More recently, it has been shown that ruthenium (Ru)-based compounds have potent antimicrobial properties and, in contrast to traditional antibiotics, these are thought to elicit antibacterial activity at multiple sites within the bacterial cell, which will undoubtedly reduce the possibility of resistance evolution. Methods MIC and MBC assays coupled with disc diffusion assays were used to screen a library of Ru-based compounds. Results One lead compound was identified that was highly active at inhibiting growth of multiple strains of P. aeruginosa at ≤32 mg/L. Crystal violet biofilm assays were performed, which showed a decrease in biomass following exposure over a 24 h period. Scanning electron microscopy was used to reveal morphological changes in the bacterial cell ultrastructure when exposed to the Ru-based compound, with evidence of membrane perturbation that supported a proposed mechanism of antimicrobial activity. Conclusions These findings make a significant contribution towards the search for novel bactericidal agents and further research is now focused on determining the potential for use as novel adjuvants within medicinal applications such as wound care management.