Biocleavable Polycationic Micelles as Highly Efficient Gene Delivery Vectors

An amphiphilic disulfide-containing polyamidoamine was synthesized by Michael-type polyaddition reaction of piperazine to equimolar N, N′-bis(acryloyl)cystamine with 90% yield. The polycationic micelles (198 nm, 32.5 mV), prepared from the amphiphilic polyamidoamine by dialysis method, can condense foreign plasmid DNA to form nanosized polycationic micelles/DNA polyelectrolyte complexes with positive charges, which transfected 293T cells with high efficiency. Under optimized conditions, the transfection efficiencies of polycationic micelles/DNA complexes are comparable to, or even higher than that of commercially available branched PEI (Mw 25 kDa)

Rapid DNA detection by beacon-assisted detection amplification

This protocol describes a new and rapid isothermal reaction process designed to amplify and detect a specific DNA sequence in purified DNA extracted from cultured cells. The protocol uses a DNA nanomachine that comprises two molecular switches that function in concert to isothermally amplify and detect a DNA target. First, a molecular beacon detection switch is 'activated' only if a DNA target sequence is present. A DNA primer and DNA polymerase are used to lock the beacon in an activated conformation. Second, an amplification and signal-transduction switch is initiated following successful activation. A nicking endonuclease and the DNA polymerase are used to replicate the DNA target. Both switches operate simultaneously at 40 °C in a single reaction to rapidly generate multiple copies of the DNA target in a cyclic polymerization reaction. This protocol enables femtomole amounts of a DNA target to be reproducibly amplified and detected i

Development and In Vitro Characterization of Galactosylated Low Molecular Weight Chitosan Nanoparticles Bearing Doxorubicin

The aim of the present research was to evaluate the potential of galactosylated low molecular weight chitosan (Gal-LMWC) nanoparticles bearing positively charged anticancer, doxorubicin (DOX) for hepatocyte targeting. The chitosan from crab shell was depolymerized, and the lactobionic acid was coupled with LMWC using carbodiimide chemistry. The depolymerized and galactosylated polymers were characterized. Two types of Gal-LMWC(s) with variable degree of substitution were employed to prepare the nanoparticles using ionotropic gelation with pentasodium tripolyphosphate anions. Factors affecting nanoparticles formation were discussed. The nanoparticles were characterized by transmission electron microscopy and photon correlation spectroscopy and found to be spherical in the size range 106–320 nm. Relatively higher percent DOX entrapment was obtained for Gal-LMWC(s) nanoparticles than for LMWC nanoparticles. A further increase in drug entrapment was found with nanoparticles prepared by Gal-LMWC with higher degree of substitution. A hypothesis which correlates the ionic concentration of DOX in nanoparticles preparation medium and percent DOX entrapment in cationic polymer has been proposed to explain the enhanced DOX entrapment. In-vitro drug release study demonstrated an initial burst release followed by a sustained release. The targeting potential of the prepared nanoparticles was assessed by in vitro cytotoxicity study using the human hepatocellular carcinoma cell line (HepG2) expressing the ASGP receptors on their surfaces. The enthusiastic results showed the feasibility of Gal-LMWC(s) to entrap the cationic DOX and targeting potential of developed Gal-LMWC(s) nanoparticles to HepG2 cell line