Self-assembling micelles of lipopolysaccharides (LPS) for loading hydrophobic (bio)molecules

Lipopolysaccharide (LPS) endotoxins are the most common pyrogenic biomolecules naturally present in Gram-negative bacteria membranes. Although LPS pathophysiological features are widely reported, a number of nanobiotechnological aspects perceive importance. Therefore, herein this study reports the physicochemical properties of LPS-based micelles from Escherichia coli O113, specifically focusing on their self-assembling distribution and aptitude to interact with four different (bio)molecules [i.e., chloroquine (CQ), curcumin (CCM), vemurafenib (VEM), and doxorubicin (DOX)]. The critical micelle concentration of LPS (CMCLPS) in an aqueous environment was determined to be 0.020 mg/mL, using a pyrene fluorescence emission spectra technique. The interaction of LPS and hydrophobic (bio)molecules was evaluated as a function of encapsulation parameters at the highest LPS concentration (CLPS of 0.043 mg/mL, i.e. >CMCLPS) for namely drug loading (DL) and encapsulation efficiency (EE). The DL results for CQ, CCM, VEM, and DOX were 28, 26, 22, and 20%, with 83, 80, 76, and 74% for their EE parameter, respectively. A straightforward relationship was observed for CLPS that increased jointly with micelle size (DH at 0.043 mg/ mL > DH at 0.020 mg/mL). The presence of the (bio)molecules also affected LPS micelle size where DH was 51 nm (control micelles), which increased to 58, 58, 55, and 55 nm for CQ, CCM, VEM, and DOX, respectively, at a CLPS of 0.043 mg/mL. This trend demonstrates that increasing LPS micelle size (>CMCLPS) enhances the encapsulation capacity of the hydrophobic (bio)molecules. The understanding and characterization of the LPS-based micelles and their interaction with (bio)molecules could lead to novel applications in nanobiotechnology, such as the potential use of LPS, e.g., as drug/vaccine nanocarriers in the near future.(c) 2022 Elsevier B.V. All rights reserved.