We have developed a novel method to protect DNA from cleavage using bioconjugated nanoparticles. Positively charged amino-modified silica nanoparticles have been directly prepared using water-in-oil microemulsion. Plasmid DNA can be easily enriched onto the positively charged nanoparticle surface, and the DNA strands are well protected from enzymatic cleavage. When incubated with nuclease enzyme for enzymatic cleavage, free plasmid DNA strands are completely cleaved, while those on the nanoparticle surfaces are intact. Our results clearly demonstrate unique properties of nanomaterials when combined with biomolecules. Our simple bionanotechnology will be highly useful in DNA separation, manipulation, and detection, and possibly in genetic engineering and gene therapy, as plasmid DNA can be protected in cellular environments without any change in its property.

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Berberine chloride (BBR) is a natural isoquinoline alkaloid extracted from medicinal herbs. It has been reported that the intestinal absorption of BBR is very low. In this study, the absolute bioavailability of BBR was studied, and the enhancing effects of D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) on intestinal absorption were investigated in rats. BBR injection was administrated via the femoral vein at a dose of 1.0 mg kg(-1) in intravenous group, and BBR oral formulations were administrated by oral gavage at a dose of 100 mg kg(-1) in BBR control (control) group and BBR-TPGS (test) group, respectively. The result showed that BBR had a very low absolute bioavailability of 0.68%, and TPGS could enhance intestinal absorption of BBR significantly. TPGS at a concentration of 2.5% could improve peak concentration (C(max)) and area under the curve (AUC(0-36)) of BBR by 2.9 and 1.9 times, respectively. The absorption enhancing ability of TPGS may be due to its ability to affect the biological activity of P-glycoprotein and thereby reduce the excretion of absorbed BBR into the intestinal lumen. This study indicated that absolute bioavailability of BBR was 0.68% in rats, and TPGS was a good absorption enhancer capable of enhancing intestinal absorption of BBR significantly.

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