Liposome adsorption to Candida albicans

Quaternary ammonium-based biomedical materials: State-of-the-art, toxicological aspects and antimicrobial resistance

Microbial infections affect humans worldwide. Many quaternary ammonium compounds have been synthesized that are not only antibacterial, but also possess antifungal, antiviral and anti-matrix metalloproteinase capabilities. Incorporation of quaternary ammonium moieties into polymers represents one of the most promising strategies for preparation of antimicrobial biomaterials. Various polymerization techniques have been employed to prepare antimicrobial surfaces with quaternary ammonium functionalities; in particular, syntheses involving controlled radical polymerization techniques enable precise control over macromolecular structure, order and functionality. Although recent publications report exciting advances in the biomedical field, some of these technological developments have also been accompanied by potential toxicological and antimicrobial resistance challenges. Recent evidenced-based data on the biomedical applications of antimicrobial quaternary ammonium-containing biomaterials that are based on randomized human clinical trials, the golden standard in contemporary medicinal science, are included in the present review. This should help increase visibility, stimulate debates and spur conversations within a wider scientific community on the implications and plausibility for future developments of quaternary ammonium-based antimicrobial biomaterials.

Propylene glycol liposomes as a topical delivery system for miconazole nitrate: comparison with conventional liposomes

Propylene glycol (PG)-phospholipid vesicles have been advocated as flexible lipid vesicles for enhanced skin delivery of drugs. To further characterize the performance of these vesicles and to address some relevant pharmaceutical issues, miconazole nitrate(MN)-loaded PG nanoliposomes were prepared and characterized for vesicle size, entrapment efficiency, in vitro release, and vesicle stability. An issue of pharmaceutical importance is the time-dependent, dilution-driven diffusion of propylene glycol out of the vesicles. This was addressed by assessing propylene glycol using gas chromatography in the separated vesicles and monitoring its buildup in the medium after repeated dispersion of separated vesicles in fresh medium. Further, the antifungal activity of liposomal formulations under study was assessed using Candida albicans, and their in vitro skin permeation and retention were studied using human skin. At all instances, blank and drug-loaded conventional liposomes were included for comparison. The results provided evidence of controlled MN delivery, constant percent PG uptake in the vesicles (≈45.5%) in the PG concentration range 2.5 to 10%, improved vesicle stability, and enhanced skin deposition of MN with minimum skin permeation. These are key issues for different formulation and performance aspects of propylene glycol-phospholipid vesicles.

Interactions between dialkyldimethylammonium bromides (DXDAB) and sterols--a monolayer study

Langmuir monolayers of cholesterol/ergosterol and dialkyldimethylammonium bromides (DXDABs) differing in alkyl chain length-14 (DTDAB), 16 (DHDAB), and 18 (DODAB)-spread at the air/water interface are examined. All the systems investigated are found to be nonideal and miscible. Negative values of the total free energy of mixing, proving film stability in the whole range of compositions and surface pressures, are observed for all the studied mixtures except for DTDAB/cholesterol. The strength of interactions, quantified with DeltaG(Exc) values, was found to be of the same order for mixtures of cholesterol/ergosterol and DHDAB or DODAB. Differences occurring for the mixtures of DTDAB with sterols indicate the affinity of DTDAB to ergosterol in contrast to cholesterol.