Poly(ethylene glycol)-induced DNA condensation in aqueous/methanol containing low-molecular-weight electrolyte solutions.

Promoting DNA loading on magnetic nanoparticles using a DNA condensation strategy

“…We ascribe the observed enhancement of DNA loading capacity on ASMNPs to the DNA condensation phenomenon provoked by PEG/NaCl through an excluded volume mechanism [16,18]. To confirm this, a standard sedimentation study was conducted [43,44], where without using MNPs, DNA was mixed with PEG 8000 (0-30%)/NaCl (1 M) at room temperature for 10 min prior to sample centrifugation for 20 min at 15,000 × g to separate the precipitated DNA. Finally, the DNA concentration in the supernatant of each sample was analysed and the percentage of DNA in the precipitate was calculated.…”

“…Indeed, DNA recoveries are nearly identical at PEG 8000 concentrations >4% with or without MNPs present. The sedimentation experiment is based on the principle that DNA molecules in the coiled state do not precipitate but, in the collapsed state, DNA precipitates almost completely after centrifugation [44]. It is easy to recognize that, when PEG 8000 concentration was lower than 3.5%, no DNA condensation occurred, whereas nearly all DNA was condensed at PEG 8000 concentrations above 5.5%, indicating that DNA conformation collapse occurs at a critical PEG concentration, in agreement with well-established DNA condensation theories.…”

“…The critical concentration for complete recovery increases with decreasing PEG MW, ∼2.5%, 5.5%, 9% and 20% for PEG 20,000, PEG 8000, PEG 2000 and PEG 400, respectively. It is worth noting that there exists a concentration region where coil and globule conformations coexist specific for each PEG molecular weight [17,45,46], presumably because that the compaction of each individual DNA molecule proceeds as an all-or-none-type transition [46,47], either coiled or compacted, but each molecule transition being a discrete event [17,44,46]. In the coexistence region, only those molecules in the condensed DNA conformation will settle out.…”

Lipopolyamine-Mediated Single Nanoparticle Formation of Calf Thymus DNA Analyzed by Fluorescence Correlation Spectroscopy

“…Deviation of t D found in our FCS experiments and from calculation in ct DNA may be related to the polydispersity of ct DNA, which means that different lengths of linear DNA were measured together. However, as the DNA condensation process is regarded as an all-or-none process, it is possible to monitor the nanoparticle formation using ct DNA (64,65).…”

Functionalised magnetic microspheres with hydrophilic properties for molecular diagnostic applications

“…Angelis, Wang, & Hawkins, 1995) or selectively adsorbing target cells (Španová et al, 2003). In the presence of high concentrations of PEG 6000 and sodium chloride DNA molecules change their properties and condense to a compact relatively dense state (Kleideiter & Nordmeier, 1999;Vasilevskaya, Khokhlov, Matsuzawa, & Yoshikawa, 1995). Carboxyl group containing magnetic microspheres found application in reversible adsorption of DNA in the presence of high concentrations of PEG 600 and PEG 6000 and sodium chloride.…”