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Development of Oligonucleotide Delivery, (siRNAs), and (miRNA) Systems for Anticancer Therapeutic Strategy Immunotherapy
Published in Loutfy H. Madkour, Nanoparticle-Based Drug Delivery in Cancer Treatment, 2022
The YSK13 and YSK15 series were developed as second-generation [30]. Both YSK13 and YSK15 contain two long unsaturated carbon chains which are linked to the same sp2 carbon atom. Based on this structure, the cone shape structure of both lipids is emphasized and would be predicted to enhance membrane disruption activity because the bond angle of the sp2 carbon is fixed at 120°, which is larger than that of an sp3 carbon (~109.5). In order to examine the effect of the apparent pKa value of the MEND on in vivo gene silencing activity and cell specificity, the YSK13 and YSK15 preparations include three and four kinds of structures that contain carbon chains with different lengths between an ester bond and a dimethylamine moiety. We first confirmed that all three YSK13 preparations show a lower phase transition temperature from a lamellar phase to an inverted hexagonal phase, which indicates a higher fusogenic activity, compared to DODAP and YSK05 under acidic conditions (pH 4.0). The MEND which is composed of different YSK13 or YSK15 preparations had a pKa value from 5.70 to 7.25, depending on their lipid structure. For the gene silencing activity of the MENDs in hepatocytes, the maximal activity was found at a pKa of 6.4, a finding consistent with the previous report [20]. On the other hand, interestingly, for gene silencing activity in liver sinusoidal endothelial cells (LSECs), the maximal activity was found at a pKa of 7.0 or higher. The intrahepatic distribution of the MEND clearly depended on their pKa values. Specifically, the MEND with a lower pKa value (<6.0) showed a hepatocyte-specific distribution. On the other hand, the intrahepatic distribution of the MENDs was shifted to LSECs depending on the extent of increase in their pKa value. Notably, only a 0.3-point difference in the pKa value resulted in a different intrahepatic distribution. Therefore, based on our findings, we conclude that fine-tuning of the pKa value is essential, not only for gene silencing activity in target cells but also for cell specificity. Moreover, we found that an ester bond in the YSK13 lipid structure can be cleaved by the phospholipase A1 activity of endothelial lipases, which are present on the surface of the endothelial cells but not on hepatocytes, and the YSK13-MEND was inactivated only in LSECs. Based on this fact, the hepatocyte specificity of the YSK13-C3-MEND on gene silencing was increased by >67-fold against LSECs, which was much higher than that of the YSK05-MEND (8.3-fold). Taken together, both the pKa value and lipase sensitivity of the lipid component are key determinants of the quality of siRNA delivery to hepatocytes.
Immobilization and characterization of lipase from an indigenous Bacillus aryabhattai SE3-PB isolated from lipid-rich wastewater
Published in Preparative Biochemistry and Biotechnology, 2018
Adegoke Isiaka Adetunji, Ademola Olufolahan Olaniran
The structural characteristics of alginate beads prepared by physical methods have been extensively studied by many researchers.[43] SEM analysis shows the formation of pores on the bead surface, and microspheres, which create microenvironment for enhanced enzyme-substrate reaction (Figure 1). Zhan et al.[44] reported similar findings during characterization of phospholipase A1 immobilized in polyvinyl alcohol-alginate matrix using SEM.