Biophysical and biochemical properties of a binary lipid mixture for DNA transfection
ABSTRACT The phase and miscibility behavior of a triple-chain phosphatidylcholine (TPHPC) and a single-chain surfactant (CTAB) were investigated in aqueous dispersions and in monolayers at the air/water interface. CTAB can be incorporated in the TPHPC monolayer because of its complementary molecule shape and reduces the tilt angle of TPHPC. The type of phases and the phase sequence (L2 - LS) are the same in the pure TPHPC monolayer and in the TPHPC/CTAB (80:20 mol:mol) mixture. No indication of any ordering of adsorbed DNA was observed. In the aqueous dispersions, TPHPC exhibits an inverted hexagonal phase above the chain melting. The addition of 30 mol% CTAB leads to the appearance of a lamellar Lalpha phase. The binding of DNA to the mixture is obvious but this is accompanied by a separation of the two lipids what is supported by monolayer experiments. The system has no long-term stability. The main reason seems to be not only the stronger interaction of DNA with CTAB, but also especially the unexpected weak interaction between CTAB and TPHPC. The transfection efficiency is lower compared with lipofectamine. The main disadvantage of this system is the cytotoxicity of CTAB, which could not be lowered by incorporation of CTAB in the TPHPC bilayer.
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ABSTRACT: There have been increasing interests in applying gold nanoparticles in biological research, drug delivery, and therapy. As the interaction of gold nanoparticles with cells relies on properties of nanoparticles, the cytotoxicity is complex and still under debating. In this work, we investigate the cytotoxicity of gold nanoparticles of different encapsulations, surface charge states, sizes and shapes to both human HEp-2 and canine MDCK cells. We found that cetyltrimethylammonium-bromide- (CTAB-) encapsulated gold nanorods (GNRs) were relatively higher cytotoxic than GNRs undergone further polymer coating and citrate stabilized gold nanospheres (GNSs). The toxicity of CTAB-encapsulated GNRs was mainly caused by CTAB on GNRs' surface but not free CTAB in the solution. No obvious difference was found among GNRs of different aspect ratios. Time-lapse study revealed that cell death caused by GNRs occurred predominately within one hour through apoptosis, whereas cell death by free CTAB was in a time- and dose-dependent manner. Both positively and negatively surface-charged polymer-coated GNRs (PSS-GNRs and PAH-PSS-GNRs) showed similar levels of cytotoxic, suggesting the significance of surface functionality rather than surface charge in this case.Journal of Nanomaterials 01/2012; DOI:10.1155/2012/375496 · 1.61 Impact Factor
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ABSTRACT: The prevention and treatment of cancer and infectious diseases requires vaccines that can mediate cytotoxic T lymphocyte-based immunity. A promising strategy is protein subunit vaccines composed of purified protein antigens and immunostimulatory adjuvants, such as Toll-like receptor (TLR) agonists. In this research, we developed two new biodegradable polymeric delivery vehicles for protein antigens and TLR agonists, as model vaccine delivery systems. This work was guided by the central hypothesis that an effective vaccine delivery system would have stimulus-responsive degradation and release, biodegradability into excretable non-acidic degradation products, and the ability to incorporate various TLR-inducing adjuvants. The first vaccine delivery system is a cross-linked polyion complex micelle which efficiently encapsulates proteins, DNA, and RNA. The micelle-based delivery system consists of a block copolymer of poly(ethylene glycol) (PEG) and poly(L-lysine), cross-linked by dithiopyridyl side groups to provide transport stability and intracellular release. The second delivery system consists of solid biodegradable microparticles encapsulating proteins, nucleic acids, and hydrophobic compounds. The microparticles are composed of pH-sensitive polyketals, which are a new family of hydrophobic, linear polymers containing backbone ketal linkages. Polyketals are synthesized via a new polymerization method based on the acetal exchange reaction and degrade into non-acidic, excretable degradation products. In addition, the technique of hydrophobic ion pairing was utilized to enhance the encapsulation of ovalbumin, DNA, and RNA in polyketal microparticles via a single emulsion method. Using in vitro and in vivo immunological models, we demonstrated that the micelle- and polyketal-based vaccine delivery systems enhanced the cross-priming of cytotoxic T lymphocytes. The model vaccines were composed of ovalbumin antigen and various TLR-inducing adjuvants including CpG-DNA, monophosphoryl lipid A, and dsRNA. The results demonstrate that the cross-linked micelles and polyketal microparticles have considerable potential as delivery systems for protein-based vaccines. Ph.D. Committee Chair: Dr. Niren Murthy; Committee Member: Dr. Carson Meredith; Committee Member: Dr. Julia Babensee; Committee Member: Dr. Mark Prausnitz; Committee Member: Dr. Ravi Bellamkonda
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ABSTRACT: A robust functionalized procedure for gold nanorods (Au NR) with mercaptoundecanoic acid (MUA), which are assembled with nanoparticles, has been reported in the present work. The self-assembled nanostructures were characterized by UV–Vis-NIR spectrophotometer and transmission electron microscopy (TEM). Self-assembly procedures, governed by surface chemistry, indicated that chemical reactivity of nanomaterial may contribute in construction of potential nanoscale assemblies. These nanostructures have striking applications as single-molecule detection, plasmonics, and sensing.Journal of Nanoparticle Research 01/2013; 15(1). DOI:10.1007/s11051-012-1404-5 · 2.28 Impact Factor