A pH-sensitive silica nanoparticles for colon-specific delivery and controlled release of catechin: Optimization of loading efficiency and in vitro release kinetics.

Catechin is a naturally occurring flavonoid of the flavan-3-ol subclass with numerous biological functions; however, these benefits are diminished due to several factors, including low water solubility and degradation in the stomach's harsh environment. So, this study aimed to develop an intelligent catechin colon-targeting delivery system with a high loading capacity. This was done by coating surface-decorated mesoporous silica nanoparticles with a pH-responsive enteric polymer called Eudragit®-S100. The pristine wormlike mesoporous silica nanoparticles (< 100 nm) with high surface area and large total pore volume were effectively synthesized and modified with the NH2 group using the post-grafting strategy. Various parameters, including solvent polarity, catechin-carrier mass ratio, and adsorption time, were studied to improve the loading of catechin into the aminated silica nanoparticles. Next, the negatively charged Eudragit®-S100 was electrostatically coated onto the positively charged aminated nanocarriers to shield the loaded catechin from the acidic environment of the stomach (pH 1.9) and to facilitate site-specific delivery in the acidic environment of the colon (pH 7.4). The prepared nanomaterials were evaluated using several methods, including The Brauner-Emmett-Teller, surface area analyzer, zeta sizer, Field Emission Scanning Electron Microscope, Powder X-Ray Diffraction, Fourier Transform Infrared Spectroscopy, Energy-Dispersive X-ray Spectroscopy, and Differential Scanning Calorimetry. In vitro dissolution studies revealed that Eudragit®-S100-coated aminated nanomaterials prevented the burst release of the loaded catechin in the acidic environment, with approximately 90% of the catechin only being released at colonic pH (pH > 7) with a supercase II transport mechanism. As a result, silica nanoparticles coated with Eudragit®-S100 would provide an innovative and promising approach in targeted nanomedicine for the oral delivery of catechin and related medicines for treating diseases related to the colon, such as colorectal cancer and irritable bowel syndrome.

Synthesis and Evaluation of High Functionality and Quality Cell-penetrating Peptide Conjugated Lipid for Octaarginine Modified PEGylated Liposomes In U251 and U87 Glioma Cells.

The use of peptide ligand modified PEGylated liposomes has been widely investigated for tumor targeting. Peptides are mainly inserted in the liposomal lipid bilayer using PEG2K-lipid spacer (Peptide-PEG2K-DSPE). However, a lower cellular uptake from longer nonlinear PEG2K spacer was reported, we here synthesized a high functionality and quality (HFQ) lipid with a short, linear serine-glycine repeated peptide [(SG)5] spacer. The objective of the current study is to develop novel octaarginine (R8) peptide-HFQ lipid grafted PEGylated liposomes for glioma cells targeting. In vitro liposomes characterization showed that the mean particle size of all liposomal formulations was in the nano-scale range < 120 nm, with a small PDI value (i.e. ∼0.2) and had a spherical shape under Transmission Electron Microscope, indicating a homogenous particle size distribution. The flow cytometry in vitro cellular association data with U251 MG and U87 cells revealed that 1.5% R8-(SG)5-lipid-PEGylated liposomes exhibited significantly higher cellular association of ∼15.87 and 7.59-fold than the conventional R8-PEG2K-lipid-PEGylated liposomes (10.4 and 6.19-fold), respectively, relative to the unmodified PEGylated liposomes. Moreover, intracellular distribution studies using confocal laser scanning microscopy (CLSM) corroborated the results of the in vitro cell association. The use of ligand-HFQ-lipid liposomes could be a potential alternative to ligand-PEG2K-lipid-modified liposomes as a drug delivery system for tumor targeting.