Bio Focus: Shape affects success in DNA nanoparticle therapy
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o Focus Shape affects success in DNA nanoparticle therapy
T
he shapes of nanoparticles can play important roles in determining their uptake by cells, and in vivo transport in biomedical applications and gene therapy. Providing a means of regulating the transfer of DNA to target sites in vivo, a research group from Johns Hopkins and Northwestern universities, led by HaiQuan Mao and Erik Luijten, respectively, has now discovered a method to control the shape of condensed DNA-block copolymer nanoparticles, and has shown that this may contribute to the development of a more effective drug delivery system that can be used in treating cancer and other diseases. This study, published in the January 11 issue of Advanced Materials (DOI: 10.1002/adma.201202932; p. 227), is also noteworthy because it does not use a virus to carry DNA into cells, an approach which can pose health risks during gene therapy. The nanoparticles developed in this research are formed by compressing DNA with a block copolymer of cation-
and the outgoing light, one can deduce information on the properties of the spin waves, ” said PSI postdoc Kejin Zhou, who conducted these measurements. It is generally accepted that superconductivity arises through “Cooper Pairs” of two electrons “glued” together.
In a high-temperature superconductor, magnetic interactions could potentially be responsible for binding the electron pairs. “Spin waves are the hottest candidates for this,” said Thorsten Schmitt, leader of PSI’s Spectroscopy of Novel Materials Group.
ic phosphoester and polyethylene glycol (PEG) in solvent mixtures with different polarities. Electrostatic neutralization between the DNA and polycation drives the assembly, forming a complex core coated with a protective PEG corona. The solvent polarity dictates the interactions between the solvent and the DNA, the polycation blocks, and the PEG blocks, which in turn influences the condensation state of the complex core. This produces micellar nanoparticles ranging from worm- and rod-like to spheroidal shapes. The dense PEG corona renders the surface of the nanoparticles electrostatically neutral and improves their colloidal stability in serum-containing medium. As a result, these “protected” DNA-compacting nanoparticles are able to evade macrophage clearance, making them more stable after injection into the body. Mao, an associate professor of materials science and engineering in Johns Hopkins’ Whiting School of Engineering, has been developing nonviral nanoparticles for gene therapy for a decade. These particles are designed to deliver their genetic payload only after they have moved through the bloodstream and entered the
target cells. Within the cells, the particle degrades and releases DNA. Using this DNA as a template, the cells can produce functional proteins that combat disease. Mao and his colleagues reported that they were able to “tune” the shapes of the particles, mimicking the shapes and sizes of viral particles. “We could observe these shapes in the lab, but we did not fully understand why
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