Staining Properties of Selected Commercial Fluorescent Dyes Toward B- and Z-DNA.

The properties of six commonly used, commercially available, fluorescent dyes were compared in staining right-handed B-DNA and left-handed Z-DNA. All showed different degree of fluorescence turn-on in the presence of B-DNA, but very little in the presence of Z-DNA. The optimal range of dye-DNA ratios of DNA was determined. While these dyes do not provide a turn-on type probe for Z-DNA, staining between B- and Z-DNA using dyes such as SYBR Green I was shown to be useful in tracking the kinetics of conformational changes between these two forms of DNA. Finally, SYBR Green I showed unique circular dichroism patterns in 4 M NaCl that change in the presence of double stranded DNA, both in the visible and UV range.

Nanomedicine to overcome antimicrobial resistance: challenges and prospects.

Translation of antibacterial nanoparticles into nanomedicine requires a deep understanding of the dynamic nature of nanoparticles and the ways they overcome immunological and biological barriers. Nanomedicines need prolonged serum stability by proper stealth coating or forming beneficial protein corona, to avoid rapid clearance by the mononuclear phagocytic system. A preferred nanoparticle formulation may include nonimmunogenic carbohydrates, which act both as a stealth coating and ligands of specific endothelium receptors to facilitate nanomedicines crossing the vascular barrier. This may lead to more rapid delivery and accumulation of nanomedicine at the infection site and provide broader and faster clinical responses than targeting specific bacterial surface receptors. Ideally, antibacterial nanomedicines should be able to penetrate biofilms through fusion and/or diffusion for targeted delivery.

Use of anion-exchange HPLC to study DNA conformational polymorphism.

Anion-exchange chromatography carried out under non-denaturing conditions is a versatile tool to differentiate DNA conformations. In this work, the utility of this form of HPLC was demonstrated in four examples. The hairpin and duplex forms of d(CG)9 were readily resolved, which allowed for the studies of the influence of salt on the equilibrium of these two forms of secondary structures. Similarly, the minimum size of Tn in the loop region required for the sequence 5'-d(CCCAA-(T)n-TTGGG)-3' to form hairpin was established to be two nucleotides using anion-exchange HPLC and fluorescence resonance energy transfer. Furthermore, the efficiency of hybridization of partially self-complementary sequences d[(CG)6Nx] was readily monitored by non-denaturing anion-exchange HPLC. Finally, different structures adopted by quadruplex-forming sequences were resolved in the same manner.