Influence of the lengths of thymine, cytosine, and adenine stretches on the two-dimensional condensation of oligodeoxynucleotides at mercury and silver amalgam electrode surfaces

N-methyl mesoporphyrin IX (NMM) as electrochemical probe for detection of guanine quadruplexes

G-quadruplexes (G4) are stable alternative secondary structures of nucleic acids. With increasing understanding of their roles in biological processes and their application in bio- and nanotechnology, the exploration of novel methods for the analysis of these structures is becoming important. In this work, N-methyl mesoporphyrin IX (NMM) was used as a voltammetric probe for an easy electrochemical detection of G4s. Cyclic voltammetry on a hanging mercury drop electrode (HMDE) was used to detect NMM with a limit of detection (LOD) of 40 nM. Characteristic reduction signal of NMM was found to be substantially higher in the presence of G4 oligodeoxynucleotides (ODNs) than in the presence of single- or double-stranded ODNs and even ODNs susceptible to form G4s but in their unfolded, single-stranded forms. Gradual transition from unstructured single strand to G4, induced by increasing concentrations of the G4 stabilizing K+ ions, was detected by an electrochemical method for the first time. All obtained results were supported by circular dichroism spectroscopy. This work expands on the concept of electrochemical probes utilization in DNA secondary structure recognition and offers a proof of principle that can be potentially employed in the development of novel electroanalytical methods for nucleic acid structure studies.

NANOG Decoy Oligodeoxynucleotide-Encapsulated Niosomes Nanocarriers: A Promising Approach to Suppress the Metastatic Properties of U87 Human Glioblastoma Multiforme Cells

Recently, advances in the synthesis and development of multifunctional nanoparticle platforms have opened up great opportunities and advantages for specifically targeted delivery of genes of interest. BSA-coated niosome structures (NISM@B) can potentially improve the efficiency in vitro delivery of nucleic acid molecules and the transfection of genes. Few studies have reported the combined use of niosomes with nucleic acid as therapeutic agents or decoy oligodeoxynucleotides (ODNs). Herein, we synthesized NISM@B to encapsulate NANOG decoy ODN (NISM@B-DEC), after which the physicochemical characteristics and in vitro and in vivo properties of NISM@B-DEC were investigated. Our results regarding physicochemical characteristics revealed that the stable niosome nanocarrier system was successfully synthesized with a regular spherical shape and narrow size distribution with proper zeta-potential values and had an appropriate biocompatibility. The ODN release from the niosome nanocarrier system exhibited controlled and pH-dependent behavior as the best models to explain the ODN release profile. NISM@B-DEC was efficiently taken up by human glioblastoma cells (U87) and significantly inhibited cell growth. Finally, blockage of the NANOG pathway by NISM@B-DEC resulted in G1 cell cycle arrest, apoptosis, and cell death. In addition, NISM@B-DEC caused a significant decrease in tumor formation and improved wound-healing efficiency of the U87 cells. These findings confirm that NISM@B-DEC could potentially suppress the metastatic ability of these cells. It can be concluded that the presented nanocarrier system can be a promising approach for targeted gene delivery in cancer therapy.