Background/Objectives: Curcumin has well-established efficacy in a variety of disorders due to its prominent antioxidant, antiaging, anti-inflammatory, chemosensitizing, and anticancer activities. Despite its numerous benefits, curcumin exhibits low bioavailability mainly due to its poor solubility, poor absorption, rapid metabolism, and quick excretion, consequently limiting its clinical applications. In this study, we investigated the most convenient ingredients in SLNs to enhance curcumin’s solubility by examining the effects of multiple independent variables simultaneously using an experimental design. Methods: After curcumin’s saturation solubility was investigated, SLN formulations were produced. The optimum formulation was determined with the help of experimental design. The SLNs were characterized in terms of the particle size and distribution, zeta potential, shape, entrapment efficiency, drug loading capacity, and drug release. The cell viability and cell internalization were also evaluated. Results: An impressive synergistic effect was achieved with the combination of Brij and Gelucire 48/16, which increased curcumin’s solubility in water by 452.5 times. Curcumin-loaded SLNs were successfully produced with a spherical shape and particle size of 389.3 ± 9.95 nm. The encapsulation efficiency was directly proportionate to the amount of curcumin and the stirring speed. Curcumin in the SLNs entered the cancer cells more easily than curcumin alone. Conclusions: Our results demonstrate that the quantity of surfactant is a significant factor influencing the efficiency of drug loading. Finally, the 3:1 (Brij–Gelucire48/16) ratio markedly enhanced the loading efficiency. The cellular internalization and, consequently, the anticancer efficacy against adenocarcinomic human alveolar basal epithelial cells were improved with SLNs. This could be a promising approach for lipid-based colloidal drug delivery systems.

Respiratory infections caused by coronaviruses (CoVs) have become a major public health concern in the past two decades as revealed by the emergence of SARS-CoV in 2002, MERS-CoV in 2012, and SARS-CoV-2 in 2019. The most severe clinical phenotypes commonly arise from exacerbation of immune response following the infection of alveolar epithelial cells localized at the pulmonary blood-air barrier. Preclinical rodent models do not adequately represent the essential genetic properties of the barrier, thus necessitating the use of humanized transgenic models. However, existing monolayer cell culture models have so far been unable to mimic the complex lung microenvironment. In this respect, air-liquid interface (ALI) models, tissue engineered models, and organ-on-a-chip systems, which aim to better imitate the infection site microenvironment and microphysiology, are being developed to replace the commonly used monolayer cell culture models, and their use is becoming more widespread every day. On the other hand, studies on the development of nanoparticles that mimic respiratory viruses, and those nanoparticles used in therapy are progressing rapidly. The first part of this review describes in vitro models that mimic the blood-air barrier, the tissue interface that plays a central role in COVID-19 progression. In the second part of the review, nanoparticles mimicking the virus and/or designed to carry therapeutic agents are explained and exemplified.

The concurrent topical delivery of Retinol and Vitamin C (Vit C) poses notable formulation challenges due to their contrasting solubility characteristics and chemical stability. In this study, liposomal nanocarriers were engineered via high-pressure microfluidization to achieve co-encapsulation of Retinol and Vit C within a single vesicular system. The formulations were characterized in terms of physicochemical stability (particle size distribution, polydispersity index, zeta potential, scanning electron microscopy (SEM)), release profiles of the actives by Franzcell diffusion test. Liposomes exhibited nanoscale particle sizes and maintained electrostatic stability over 60 days period. These results indicated that microfluidization was an easy but appropriate method for producing liposomes. Franz diffusion cell studies revealed sustained release of Vit C from liposomes compared to its simple gel and solutions, while retinol did not show considerable difference probably due to its limiting diffusion ability through the membranes. Collectively, the findings support the feasibility of utilizing phospholipid-based vesicular systems for sustained delivery of chemically distinct bioactives. The developed liposomes offer a promising platform for dermal anti-ageing and antioxidant delivery, warranting further investigation in vivo to substantiate long-term efficacy and better cutaneous compatibility.