The increasing antibiotic resistance towards a panel of microorganisms is one of the public health concerns. For this reason, the search for alternatives to the widely used antibiotic has been undertaken. In the era of sustainable chemistry, deep eutectic solvents (DESs) have emerged as promising antimicrobial agents. These solvents possess several advantages such as low volatility, low flammability, ease of preparation, and typically low cost of production. These properties make DES suitable for various applications, including extraction of biomolecules and preparation of cosmetics. Natural DESs (NADESs) are special category of DESs prepared from natural sources, which matched the recent trends of leaning back to nature, and decreasing dependence on synthetic precursors. NADES can be prepared by heating and stirring, freeze-drying, evaporation, grinding, and ultrasound-assisted and microwave-assisted synthesis. Utilizing NADESs as an alternative to traditional antibiotics, which become ineffective over time due to bacterial resistance, holds great promise for these reasons. This review aims to discuss the antimicrobial properties of multiple NADESs, including antibacterial and antifungal activities. To the best of our knowledge, this review is the first literature survey of the antimicrobial activities of NADESs. Key points: • Natural deep eutectic solvents are promising antimicrobial alternative to antibiotics • NADES holds high potential for their activity against bacterial resistance • NADES have also substantial antifungal activities

The increasing prevalence of multidrug-resistant pathogens is a critical public health issue, necessitating the development of alternative antibacterial agents. Examples of these pathogens are methicillin-resistant Staphylococcus aureus (MRSA) and the emergence of “pan-resistant” Gram-negative strains, such as Pseudomonas aeruginosa and Acinetobacter baumannii, which occurred more recently. This review examines various emerging materials with significant antibacterial activities. Among these are nanomaterials such as quantum dots, carbon quantum dots, metal–organic frameworks (MOFs), covalent organic frameworks (COFs), and layered double hydroxides, all of which demonstrate excellent antibacterial properties. Interestingly, including antibacterial agents within the structure of these materials can help avoid bacterial resistance and improve the long-term efficacy of the materials. Additionally, the antibacterial potential of liquid solvents, including ionic liquids and both deep eutectic solvents and natural deep eutectic solvents, is explored. The review discusses the synthesis methods, advantages, and antibacterial efficacy of these new materials. By providing a comprehensive overview of these innovative materials, this review aims to contribute to the ongoing search for effective solutions to combat antibiotic resistance. Key studies demonstrating antibacterial effects against pathogens like Escherichia coli, Staphylococcus aureus, and multidrug-resistant strains are summarized. MOFs have exhibited antibacterial properties through controlled ion release and surface interactions. COFs have enhanced the efficacy of encapsulated antibiotics and displayed intrinsic antibacterial activity. Other nanomaterials, such as quantum dots, have generated reactive oxygen species, leading to microbial inactivation. This review aims to provide insights into these new classes of antibacterial materials and highlight them for addressing the global crisis of antibiotic resistance. Key points: • Nanomaterials show strong antibacterial effects against drug-resistant bacteria • Emerging solvents like ionic liquids offer novel solutions for bacterial resistance • MOFs and COFs enhance antibiotic efficacy, showing promise in combating resistance

The need for novel antibacterial and antifungal treatments originates from the growing incidence of multidrug-resistant organisms, which is a serious public health concern. Conventional antibacterial and antifungal drugs are restricted by their narrow activity spectrum and lack of appropriate targets. The rise of antifungal drug resistance has made numerous commonly used drug classes ineffective, greatly complicating the clinical treatment of fungal infections. Additionally, bacteria and fungi that form biofilms are considered a major public health issue because they evade host defenses and contribute to antimicrobial resistance. To overcome these challenges, novel alternatives such as ionic liquids (ILs) have been developed. These compounds exhibit antifungal and antibacterial properties and can additionally function as antibiofilm agents. This review explores the nature of these materials, their methods of preparation, their uses, and their advantages. Furthermore, the antimicrobial activities of various ILs toward Gram-positive bacteria, Gram-negative one, and fungal species (spp) are discussed. Additionally, different mechanisms of action of these materials, along with their antibiofilm activity, will be discussed in this review.

Objectives: This study was designed to optimize a ceftazidime (CTZ)-loaded nanocarrier that could efficiently permeate across corneal tissues. Moreover, N-acetylcysteine (NAC) was combined with an optimized CTZ-loaded formula to augment the antimicrobial activity and facilitate the efficient healing of Pseudomonas aeruginosa-induced keratitis. Methods: Different CTZ-loaded invasomes (INVs) and CTZ-loaded nanostructured lipid carriers (NLC) were fabricated and fully characterized via the determination of the entrapment efficiency (EE%), particle size (PS), surface charge, and percentage of CTZ release. Next, NAC was added to the optimized formulae from each nanocarrier, which were further assessed through ex vivo corneal permeation and in vitro antimicrobial activity studies. Finally, an in vivo evaluation of the optimal nanocarrier in the presence of NAC was performed. Results: Both nanocarriers showed nanoscale PS with sufficient surface charges. CTZ-loaded NLC formulae showed a higher EE% range with a sustained drug release profile. Both optimized formulae showed a spherical shape and excellent stability. Moreover, the antibacterial activity and biofilm inhibition assessments confirmed the synergistic effects of NAC when combined with different CTZ-loaded nanocarriers. However, the optimized CTZ-loaded INV formula achieved higher corneal permeation and deposition compared to the optimized CTZ-loaded NLC formula. Finally, the in vivo assessment confirmed the dominance of the optimized CTZ-loaded INV formula combined with NAC, where the microbiological, histopathological, and immunohistopathological examinations showed the rapid eradication of keratitis. Conclusions: Recent strategies for the incorporation of antibiotics into nanocarriers, combined with mucolytic agents, can offer a promising platform to boost the therapeutic efficiency of antibiotics and prevent antimicrobial resistance.