PubMed · 3556743
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T D Madden, M J Hope, P R Cullis. 1987. Modelling the biological membrane.. https://doi.org/10.1042/bst0150075
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Identifying and quantifying an active adjuvant along with its degradants in drug formulations is essential for ensuring the safety and efficacy of the drug product. QS-21 is a potent adjuvant that is being evaluated in several clinical trials and is currently formulated in licensed vaccines that protect against shingles, malaria, and RSV. In aqueous environments, QS-21 is subject to hydrolytic degradation that is influenced by pH and temperature, resulting in the formation of a degradant known as QS-21 Hydrolyzed Product, QS-21 HP, which can occur during manufacturing and/or prolonged storage. The intact QS-21 and QS-21 HP induce distinct immune response profiles, making it critical to monitor the degradation of QS-21 in vaccine adjuvant formulations. To date, there has been a paucity of reliable assays for QS-21, its isomers, and degradant QS-21 HP in liposomal adjuvant formulations available that can be transferred seamlessly in quality control (QC) environments. Herein, we introduce a simple and QC-friendly liquid chromatography coupled to a charged aerosol detector (LC-CAD) enabled by stationary phase screening combined with in silico method development optimization. The method exploits 2.7 μm fused-core phenyl hexyl particles, ensuring its versatility in standard and ultra-high pressure LC systems. This approach demonstrates a high correlation between predicted retention time (RT) and experimental outcomes with overall ∆RT < 4%. In addition, this assay shows great linearity, precision, specificity, and accuracy to advance process development characterization of new vaccine formulations.
Positive nanoparticles have often a higher uptake than neutral and negative nanoparticles. This is usually attributed to electrostatic interactions with negatively charged proteoglycans on the cell membrane. However, upon contact with serum, nanoparticles adsorb a biomolecule corona and tend toward neutrality, suggesting that electrostatic interactions alone cannot explain the different uptake. Here, we used oppositely charged liposomes as an example to explore at a fundamental level why positive nanoparticles usually show a higher uptake than the negative ones. Two proteomic-based approaches were combined to compare their protein coronas and the cell surface proteins involved in their internalization. The results showed that the higher uptake of the positive liposomes used for this study could not be simply explained by the involvement of specific corona proteins and dominating cell surface proteins. Instead, small differences in the abundances of a large number of corona proteins and cell surface proteins were observed, including multiple low-abundance proteins. Importantly, the positive liposomes had higher uptake than the negative liposomes only when added to cells in the presence of serum, suggesting that the higher uptake likely resulted from the observed subtle differences in their corona and the collective contribution and interactions with multiple cell surface proteins.
Precise intracellular delivery of biologic therapeutics remains a major challenge due to endosomal entrapment and inefficient delivery systems. Here, we develop a bioinspired platform that uses Streptolysin O (SLO), a member of the cholesterol-dependent cytolysin (CDC) family, for cytosolic cargo delivery. This delivery system incorporates an affibody for selective targeting and endocytosis and a redox-cleavable PEG-conjugated dithiol-ethyl carbonate linker (PEG-DEC) that reversibly inactivates SLO extracellularly. After endosomal uptake, the reductive intracellular environment removes the PEG layer, reactivating SLO to induce localized endosomal disruption and cargo release. This mechanism minimizes off-target toxicity while promoting efficient cytosolic delivery of diverse cargo, including doxorubicin (DOX), the fluorescent protein GFP and mApple, and the enzyme NanoLuciferase (NanoLuc) and lactate oxidase (LOX). PEGylated SLO exhibited significantly improved cytosolic release efficiency compared with conventional liposomal formulations, confirming the advantage as a controllable intracellular delivery module.