Antiadhesion effect of the C17 glycerin ester of isoprenoid-type lipid forming a nonlamellar liquid crystal

Lipidic lyotropic liquid crystals: Insights on biomedical applications

Liquid crystals (LCs) possess unique physicochemical properties, translatable into a wide range of applications. To date, lipidic lyotropic LCs (LLCs) have been extensively explored in drug delivery and imaging owing to the capability to encapsulate and release payloads with different characteristics. The current landscape of lipidic LLCs in biomedical applications is provided in this review. Initially, the main properties, types, methods of fabrication and applications of LCs are showcased. Then, a comprehensive discussion of the main biomedical applications of lipidic LLCs accordingly to the application (drug and biomacromolecule delivery, tissue engineering and molecular imaging) and route of administration is examined. Further discussion of the main limitations and perspectives of lipidic LLCs in biomedical applications are also provided. STATEMENT OF SIGNIFICANCE: Liquid crystals (LCs) are those systems between a solid and liquid state that possess unique morphological and physicochemical properties, translatable into a wide range of biomedical applications. A short description of the properties of LCs, their types and manufacturing procedures is given to serve as a background to the topic. Then, the latest and most innovative research in the field of biomedicine is examined, specifically the areas of drug and biomacromolecule delivery, tissue engineering and molecular imaging. Finally, prospects of LCs in biomedicine are discussed to show future trends and perspectives that might be utilized. This article is an ampliation, improvement and actualization of our previous short forum article "Bringing lipidic lyotropic liquid crystal technology into biomedicine" published in TIPS.

Barrier materials for prevention of surgical adhesions: systematic review

BACKGROUND

Postoperative surgical adhesions constitute a major health burden internationally. A wide range of materials have been evaluated, but despite constructive efforts and the obvious necessity, there remains no specific barrier widely utilized to prevent postoperative adhesion formation. The aim of this study was to highlight and characterize materials used for prevention of postoperative surgical adhesions in both animal and human studies.

METHODS

A systematic review was performed of all original research articles presenting data related to the prevention of postoperative adhesions using a barrier agent. All available observational studies and randomized trials using animal models or human participants were included, with no restrictions related to type of surgery. PubMed and Embase databases were searched using key terms from inception to August 2019. Standardized data collection forms were used to extract details for each study and assess desirable characteristics of each barrier and success in animal and/or human studies.

RESULTS

A total of 185 articles were identified for inclusion in the review, with a total of 67 unique adhesion barrier agents (37 natural and 30 synthetic materials). Desirable barrier characteristics of an ideal barrier were identified on review of the literature. Ten barriers achieved the primary outcome of reducing the incidence of postoperative adhesions in animal studies followed with positive outputs in human participants. A further 48 materials had successful results from animal studies, but with no human study performed to date.

DISCUSSION

Multiple barriers showed promise in animal studies, with several progressing to success, and fulfilment of desirable qualities, in human trials. No barrier is currently utilized commonly worldwide, but potential barriers have been identified to reduce the burden of postoperative adhesions and associated sequelae.

Enhanced nose-to-brain delivery of tranilast using liquid crystal formulations

Intranasal administration is poised as a competent method in delivering drugs to the brain, because the nasal route has a direct link with the central nervous system bypassing the formidable blood-brain barrier. C₁₇-monoglycerol ester (MGE) and glyceryl monooleate (GMO) as liquid crystal (LC)-forming lipids possess desirable formulation characteristics as drug carriers for intranasally administered drugs. This study investigated the effect of LC formulations on the pharmacokinetics of tranilast (TL), a lipophilic model drug, and its distribution in the therapeutic target regions of the brain in rats. The anatomical biodistribution of LC formulations was monitored using micro-computed tomography tandem in vivo imaging systems. MGE and GMO effectively formed LC with suitable particle size, zeta potential, and viscosity supporting the delivery of TL to the brain. MGE and GMO LC formulations enhanced brain uptake by 10- to 12-fold and 2- to 2.4- fold, respectively, compared with TL solution. The olfactory bulb had the highest TL concentration and fluorescent signals among all the brain regions, indicating a direct nose-to-brain delivery pathway of LC formulations. LC-forming lipids, MGE and GMO, are potential biomaterials in formulations intended for intranasal administration.