Melting Transitions of DNA-Capped Gold Nanoparticle Assemblies

A Study on the Biological Activity of Optically Pure Aziridine Phosphines and Phosphine Oxides

A series of optically pure aziridine phosphines and their corresponding phosphine oxides were synthesized through established chemical methodologies. The compounds were systematically investigated for their biological properties. Notably, all synthesized compounds demonstrated moderate antibacterial activity only against the reference strain of Staphylococcus aureus. However, compounds 5 and 7 exhibited noteworthy cell viability inhibition of human cervical epithelioid carcinoma HeLa cells and endometrial adenocarcinoma Ishikawa cells. Further studies of these compounds revealed additional biological effects, including disruption of the cell membrane in high concentrations, cell cycle arrest in the S phase, and the induction of reactive oxygen species (ROS). Comparative analysis of the two classes of chiral organophosphorus derivatives of aziridines indicated that chiral phosphine oxides displayed significantly higher biological activity. Consequently, these findings suggest that chiral phosphine oxides may be potential candidates for the development of anticancer drugs. In light of the significant interest in preparations whose structure is based on a three-membered aziridine ring in terms of potential anticancer therapy, this research fits into the current research trend and should constitute a valuable addition to the current state of knowledge and the existing library of aziridine derivatives with anticancer properties.

Room temperature synthesis of NIR emitting Ag2S nanoparticles through aqueous route and its influence on structural modulation of DNA

Near infra-red (NIR) light emitting nanomaterials had shown great promise in clinical imaging in view of negligible absorption by skin or tissue of mammalian. Thus, it demands for synthesizing stable NIR emitting nanomaterials in water environment. The present work presents synthesis of biologically acceptable luminescent near-IR emitting silver sulfide nanoparticles through an aqueous route using 2-mercaptoethanol. The prepared as-synthesized Ag₂S nanoparticles exhibited bright photoluminescence with quantum yield of ca. 4%. X-ray diffraction (XRD) analysis indicated that the products were monoclinic α-Ag₂S. Fourier transform infrared spectral analysis revealed that the stretching vibration at 2560 cm^-1 responsible for S-H bond of thiol group disappeared suggesting the conjugation of 2-mercaptoethanol with Ag₂S nanoparticles. In view of investigating any possible effect on genetic materials, interactions of the synthesized particles with calf thymus DNA was investigated employing Ethidium bromide (EB) as structural probe. To understand the binding mechanism, the UV-vis absorption, fluorescence and circular dichroism (CD) spectroscopic, as well as DNA melting studies measurements were carried out. The observed results confirm that nanoparticles interact with DNA through groove binding.

DNA-conjugated gold nanoparticles based colorimetric assay to assess helicase activity: a novel route to screen potential helicase inhibitors

Helicase are essential enzymes which are widespread in all life-forms. Due to their central role in nucleic acid metabolism, they are emerging as important targets for anti-viral, antibacterial and anti-cancer drugs. The development of easy, cheap, fast and robust biochemical assays to measure helicase activity, overcoming the limitations of the current methods, is a pre-requisite for the discovery of helicase inhibitors through high-throughput screenings. We have developed a method which exploits the optical properties of DNA-conjugated gold nanoparticles (AuNP) and meets the required criteria. The method was tested with the catalytic domain of the human RecQ4 helicase and compared with a conventional FRET-based assay. The AuNP-based assay produced similar results but is simpler, more robust and cheaper than FRET. Therefore, our nanotechnology-based platform shows the potential to provide a useful alternative to the existing conventional methods for following helicase activity and to screen small-molecule libraries as potential helicase inhibitors.

Cyclodextrin induced controlled delivery of a biological photosensitizer from a nanocarrier to DNA

Addition of β-cyclodextrin to the micelle bound phenosafranin in the presence of ctDNA leads to quantitative transfer of the fluorophore from the micelle to the DNA.

Binding of an anionic fluorescent probe with calf thymus DNA and effect of salt on the probe–DNA binding: a spectroscopic and molecular docking investigation

Binding mode of biologically relevant anionic probe, ANS, with ctDNA is divulged from spectroscopic and molecular docking studies.

Unveiling the groove binding mechanism of a biocompatible naphthalimide-based organoselenocyanate with calf thymus DNA: an "ex vivo" fluorescence imaging application appended by biophysical experiments and molecular docking simulations

The present study embodies a detailed investigation of the binding modes of a potential anticancer and neuroprotective fluorescent drug, 2-(5-selenocyanato-pentyl)-6-chloro benzo[de]isoquinoline-1,3-dione (NPOS) with calf thymus DNA (ctDNA). Experimental results based on spectroscopy, isothermal calorimetry, electrochemistry aided with DNA-melting, and circular dichroism studies unambiguously established the formation of a groove binding network between the NPOS and ctDNA. Molecular docking analysis ascertained a hydrogen bonding mediated 'A-T rich region of B-DNA' as the preferential docking site for NPOS. The cellular uptake and binding of NPOS with DNA from "Ehrlich Ascites Carcinoma" cells confirmed its biocompatibility within tumor cells. Experimental and ex vivo cell imaging studies vividly signify the importance of NPOS as a potential prerequisite for its use in therapeutic purposes.