Development of Robust Cationic Light-Activated Thermosensitive Liposomes: Choosing the Right Lipids.

Extensive research has been conducted on cationic light-activated thermosensitive liposomes (CLTSLs) as a means for site-specific and controlled drug release; however, less attention has been given to the stability of these nanoparticles. Selecting the appropriate lipids is crucial for the development of a stable and responsive system. In this study, we investigated the impact of various lipids on the physical properties of cationic light-activated liposomes. Incorporating poly(ethylene glycol) PEG molecules resulted in uniform liposomes with low polydispersity index, while the addition of unsaturated lipid (DOTAP) resulted in extremely leaky liposomes, with almost 80% release in just 10 min of incubation at body temperature. Conversely, the inclusion of cholesterol in the formulation increased liposome stability too much and decreased their sensitivity to stimuli-responsive release, with only 14% release after 2 min of light exposure. To achieve stable and functional CLTSL, we substituted an equivalent amount of unsaturated lipid with a saturated lipid (DPTAP), resulting in stable liposomes at body temperature that were highly responsive to light, releasing 90% of their content in 10 s of light exposure. We also conducted two atomistic molecular dynamics simulations using lipid compositions with saturated and unsaturated lipids to investigate the effect of lipid composition on the dynamical properties of the liposomal lipid bilayer. Our findings suggest that the nature of lipids used to prepare liposomes significantly affects their properties, especially when the drug loading needs to be stable but triggered drug release properties are required at the same time. Selecting the appropriate lipids in the right amount is therefore essential for the preparation of liposomes with desirable properties.

Far-red light-triggered cargo release from liposomes b ound to a photosensitizer-cellulose nanofiber hydrogel.

In our research we used the anionic nanofibrillar cellulose (ANFC) as a platform for far-red light-induced release of cargo from liposomes. In contrast to previous works, where photosensitizers are usually in the liposomal bilayers, we used a cellulose-binding dye. Our phthalocyanine derivative has been shown to bind very strongly to cellulose and cellulose nanofiber hydrogels, allowing us to place it outside of the liposomes. Both the sensitizer and cationic liposomes bind strongly to the ANFC after mixing, making the system easy to fabricate. Upon light activation, the photosensitizer generates reactive oxygen species (ROS) within the ANFC hydrogel, where the reactive oxygen species oxidize unsaturated lipids in the liposomal membrane, which makes the liposomes more permeable, resulting in on-demand cargo release. We were able to achieve ca. 70 % release of model hydrophilic cargo molecule calcein from the hydrogels with a relatively low dose of light (262 J/cm2) while employing the straightforward fabrication techniques. Our system was remarkably responsive to the far-red light (730 nm), enabling deep tissue penetration. Therefore, this very promising novel cellulose-immobilized photosensitizer liposomal platform could be used as a controlled drug delivery system, which can have applications in externally activated coatings or implants.

Development and Validation of High-Performance Liquid Chromatography Method for the Quantification of Remdesivir in Intravenous Dosage Form.

Corona virus disease 2019 (COVID-19) has posed a mounting threat to public health with worldwide outbreak caused by a novel virus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Recently, remdesivir (RDV) has been approved by Food and Drug Administration (FDA) for treating COVID-19 patients ≥12 years old requiring hospitalization. To the best of our knowledge, a simple method to estimate RDV in the pharmaceutical formulations using high-performance liquid chromatography (HPLC) is still unexplored, highlighting the need for a precise analytical method for its quantification. The prime purpose of the current investigation was to develop and validate a well-grounded HPLC method for quantification of RDV in pharmaceutical formulations. The best chromatogram was obtained by means of an Inertsil ODS-3V column using a mobile phase of milli-Q water modified to pH 3.0 with o-phosphoric acid and acetonitrile (50:50, % v/v) at a flow rate of 1.2 mL/min and wavelength of detector set at 246 nm with retention time being achieved at 6.0 min. The method was validated following International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q2 (R1) guidelines for various parameters such as specificity and selectivity, system suitability, linearity, precision, accuracy, limits of detection and quantification, and robustness. The method developed for the quantification of RDV was found to be linear in the concentration range of 25-2,500 ng/mL with limit of detection and limit of quantification of 1.95 and 6.49 ng/mL, respectively. Assay value of 102% ± 1% was achieved for marketed injectable dosage form when estimated by the validated method. Therefore, in this study a simple, rapid, sensitive, selective, accurate, precise, and robust analytical method was developed and validated for the quantification of RDV using HPLC. The established method was successfully employed for quantification of RDV in marketed pharmaceutical formulation.