Quercetin Loaded Silica and Gold - Coated Silica Nanoparticles: Characterization, Evaluation and Comparison of Their in vitro Characteristics.

Herein, silica nanoparticles (NPs) and gold-silica NPs were loaded with the anti-cancer agent quercetin (QC) to produce silica NPs-QC and gold coated silica NPs-QC, respectively. The nanosystems were characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS) and Fourier transform infrared (FTIR). Drug encapsulation efficiency (EE), loading capacity (LC) and release rate were measured using UV spectrophotometer. The drug was encapsulated in silica NPs in a high percentage (71%) and reduced by about 16% after gold coating. The mean particle size increased after coating and QC loading with a polydispersity index (PDI) between (∼ 0.2 - 0.6) and negative zeta potential (-13 to - 15 mV). The intensity of FTIR peaks of silica NPs has been significantly decreased upon gold coating indicating a successful attachment of the gold thin layer. The drug release was slightly faster from coated compared to uncoated NPs but both slower than free QC. The percentages of their cell toxicity were almost the same but lower than free QC and generally were higher against HeLa cells compared to fibroblast cells. Both nanosystems could be considered as promising nanocarriers with reasonable EE, slower release rate and lower toxicity compared to the free drug.

Interaction of folate - Linked silica nanoparticles with HeLa cells: Analysis and investigation the effect of polymer length.

This work is a continuance to our previous findings on silica nanoparticles (NPs) modified with diamine polymer, carboxymethyl-ß-cyclodextrin (CM-ß-CD) and folic acid (FA), respectively. When four different polymer lengths (D230, D400, D2000 and D4000) were analyzed, the release rate of anticancer agents was inversely related to the polymer length while the cell toxicity was directly related to the length. We investigate here the effect of polymer length on the extent of cellular interaction with HeLa cells. The mean particle size, the polydispersity (PD) and the zeta potential of the NPs were measured using dynamic light scattering (DLS), the quantitative analysis of the extent of NPs' interaction was studied using fluorescence microscopy and transmission electron microscopy (TEM) was used to qualitatively visualize them. The particle size increased by increasing the polymer length, the PD values were within the acceptable ranges (0.3-0.5) and the zeta potential was in the range of (-16 to -20 mV). A direct relation was observed between the fluorescence intensity and the length. All modified NPs were capable of entering the cells, however a greater number of NPs with long polymers was observed compared to short polymers. Thus, the direct relation of polymer length to the cell toxicity is due to the release rate behavior and the enhanced interaction of NPs which possess long polymers.

The effect of polymer length on the in vitro characteristics of a drug loaded and targeted silica nanoparticles.

The objective of this research was to investigate the effect of polymer length on the in vitro characteristics of thymoquinone-melatonin (TQ-MLT) when loaded into our previously prepared targeted drug delivery system (TDDS). Our system constructed from silica nanoparticles (NPs) and modified with diamine polymer (D4000), carboxymethyl-ß-cyclodextrin (CM-ß-CD) and folic acid (FA), respectively. In this study, three other different lengths of polymers (D230, D400 and D2000) were used and compared to D4000. The surface modification was characterized using fourier transform infrared spectroscopy (FTIR) and the mean particle size as well as polydispersity (PD) was measured using dynamic light scattering (DLS). The results, in general, showed that the release rate increases as the polymer length decreases. Also, shorter polymers showed an obvious burst release of most of the drug within the first hour. On the other hand, longer polymers exhibited a more sustained release in a pulsatile manner, with two moderate drug burst patterns occurred within the first and the last few hours. The in vitro cell viability assay showed that the percentage of cell toxicity toward HeLa cells increases with increasing the polymer length.