Nanolipoparticles-mediated MDR1 siRNA delivery: preparation, characterization and cellular uptake

Lipid-based nanoparticles [NLP] are PEGylated carriers composed of lipids and encapsulated nucleic acids with a diameter less than 100 nm. The presence of PEG in the NLP formulation improves the particle pharmacokinetic behavior. The purpose of this study was to prepare and characterize NLPs containing MDR1 siRNA and evaluate their cytotoxicity and cellular uptake. MDR1 siRNA could be used in multidrug resistance reversal in cancer therapy. siRNAs were encapsulated into NLPs consisted of mPEG-DSPE/DOTAP/DOPE [10:50:40 molar ratio] by the detergent dialysis method. The particle diameters of NLPs and their surface charge were measured using dynamic light scattering. siRNA encapsulation efficiency was determined by an indirect method via filtration and free siRNA concentration determination. NLPs cytotoxicity was investigated by MTT assay. The ability of NLPs for siRNA delivery checked in two human cell lines [MCF-7/ADR and EPP85-181/RDB] by fluorescence microscopy and compared with oligofectamine. NLPs containing MDR1 siRNA were prepared with the stable size of 80-90 nm and the zeta potential near to neutral. The siRNA encapsulation efficacy was more than 80%. These properties are suitable for in vivo siRNA delivery. NLPs cytotoxicity studies demonstrated they were non-toxic at the doses used. NLPs improved siRNA localization in both cell lines. NLPs containing MDR1 siRNA can be a good candidate for in vivo siRNA delivery studies

novel label-free cocaine assay based on aptamer-wrapped single-walled carbon nanotubes

This paper describes a selective and sensitive biosensor based on the dissolution and aggregation of aptamer wrapped single-walled carbon nanotubes. We report on the direct detection of aptamer-cocaine interactions, namely between a DNA aptamer and cocaine molecules based on near-infrared absorption at 807. First a DNA aptamer recognizing cocaine was non-covalently immobilized on the surface of single walled carbon nanotubes and consequently dissolution of SWNTs was occurred. Vis-NIR absorption [A[807nm]] of dispersed, soluble aptamer-SWNTs hybrid, before and after incubation with cocaine was measured using a CECIL9000 spectrophotometer. This carbon nanotube setup enabled the reliable monitoring of the interaction of cocaine with its cognate aptamer by aggregation of SWNTs in the presence of cocaine. This assay system provides a mean for the label-free, concentration-dependent, and selective detection of cocaine with an observed detection limit of 49.5 nM