Interaction between DNA and trimethyl-ammonium bromides with different alkyl chain lengths

Assessing the Suitability of a Dicationic Ionic Liquid as a Stabilizing Material for the Storage of DNA in Aqueous Medium

The present study has been undertaken with an objective to find out a suitable medium for the long-term stability and storage of the ct-DNA structure in aqueous solution. For this purpose, the potential of a pyrrolidinium-based dicationic ionic liquid (DIL) in stabilizing ct-DNA structure has been investigated by following the DNA-DIL interaction. Additionally, in order to understand the fundamental aspects regarding the DNA-DIL interaction in a comprehensive manner, studies are also done by employing structurally similar monocationic ionic liquids (MILs). The investigations have been carried out both at ensemble-average and single molecular level by using various spectroscopic techniques. The molecular docking study has also been performed to throw more light into the experimental observations. The combined steady-state and time-resolved fluorescence, fluorescence correlation spectroscopy, and circular dichroism measurements have demonstrated that DILs can effectively be used as better storage media for ct-DNA as compared to MILs. Investigations have also shown that the extra electrostatic interaction between the cationic head group of DIL and the phosphate backbone of DNA is primarily responsible for providing better stabilization to ct-DNA, retaining its native structure in aqueous medium. The outcomes of the present study are also expected to provide valuable insights in designing new polycationic IL systems that can be used in nucleic acid-based applications.

Evaluation of the inhibitory efficacy of quaternary ammonium compounds on in vitro growth of Theileria equi parasite in MASP culture

Equine piroplasmosis has become a global problem of the equine husbandry sector. Haemoprotozoans evolved very quickly and developed resistance against most of the current available drugs. Phospholipid membrane synthesis by choline kinase enzyme is vital for propagation of intra-erythrocytic protozoa parasites. This pathway was targeted in the present study. Quaternary ammonium salts (QAS) and their analogues act against choline and hamper the biosynthesis process for phosphatidylcholine. We analysed anti-T. equi activity of three QAS - decamethonium bromide (DMB), decyl trimethyl ammonium bromide (DTAB) and dodecyl trimethyl ammonium bromide (DDTAB). Theileria equi parasites in vitro treated with different concentrations of DMB, DDTAB and DTAB. Drug treated T. equi failed to multiply further in the viability test. The IC₅₀ value of DMB, DDTAB and DTAB for growth inhibition of T. equi was 14.0 μM, 469.51 nM and 558.40 nM, respectively. DMB, DDTAB and DTAB treated T. equi parasites were observed to be devoid of internal structures, showing pyknotic and degenerative appearances. Various concentration of DMB, DDTAB and DTAB were analysed for their cytotoxicity and haemolytic activity on horse's PBMCs and RBCs. DMB was less than 10% cytotoxic to PBMCs, while DDTAB and DTAB were 40%-50% cytotoxic at 1000 μM concentrations. The respective CC₅₀ values were 7202.96 μM, 1026.26 μM and 1263.95 μM. DMB and DTAB showed least haemolytic activity (<3%); whereas DDTAB was more haemolytic to RBCs at highest concentration of 2000 μM. The respective CC₅₀ values of these drugs were 224495.3 μM, and 39101.35 μM; 713.54 μM. Specific selective index for DMB, DDTAB and DTAB values with respect to host's PBMC and RBC cells, were 514.50, 2185.81, 2263.52 and 16035.38, 1519.75, 70023.91, respectively. These data indicated its non-toxicity to host's cells and selective potential of anti-T. equi in vitro activity.

DNA binding, antibacterial, hemolytic and anticancer studies of some fluorescent emissive surfactant-ruthenium(II) complexes

Designing the effective metallodrugs with amphiphilic nature is an active approach for the biomedical applications such as chemotheraphy, bioimaging, drug carrier, etc. To elaborate this, some fluorescent emissive surfactant-ruthenium(II) complexes and its precursor ruthenium(II) complexes have been interacted with calf thymus DNA (CT-DNA) for understanding the biophysical impacts of head and tail parts of the metallosurfactants. Here, DNA binding studies were examined by UV-visible absorption, fluorescence, circular dichroism and viscosity measurements. The obtained results showed that surfactant-ruthenium(II) complexes effectively bind with CT-DNA through hydrophobic interactions dominated moderate intercalation, whereas precursor ruthenium(II) complexes interact CT-DNA through electrostatic interactions dominated moderate intercalation. Also, increase of hydrophobic alkyl amine chain length as well as size of the head group in surfactant-ruthenium(II) complexes increased the binding affinity with CT-DNA, in which tail group played a dominant role. Further investigations of antibacterial, hemolytic and anticancer activities showed that desired biological activities could be obtained by tuning the head and tail groups of the metallodrugs in near future.Communicated by Ramaswamy H. Sarma.

VMG II transport medium stabilises oral microbiome samples for Next-Generation Sequencing

Next-Generation Sequencing is providing insights into the critical role of the oral microbiome in dental diseases. Application of this method can require the collection of dental plaque from large cohorts in field-type conditions, which necessitates a transport medium to preserve the microbiome composition. We evaluated the use of two transport media, VMG II and RNAprotect® Bacteria Reagent (Qiagen), for room temperature storage of dental plaque. VMG II has not previously been assessed for suitability to store microbiome samples intended for deep sequencing. We compared the microbiome composition of dental plaque (total n=23) stored in either VMG II or RNAprotect Bacteria at room temperature with immediately-frozen plaque. 454 sequencing of 16S gene amplicons was used to assess the plaque microbial composition. While the bacterial diversity recovered was similar between storage conditions (p>0.1), the abundance of bacteria was influenced by storage environment. Dental plaque stored in VMG II was most similar to immediately-frozen material, with only one of the 324 bacterial species being differentially abundant (Neisseria, p<0.001). In comparison, dental plaque stored in RNAprotect Bacteria had 24 differentially abundant species compared with the immediately-frozen samples and a significantly different phylogenetic structure (p<0.01). We have identified VMG II as a new transport medium for room temperature storage of dental plaque samples being subject to Next-Generation Sequencing that stabilises oral microbial DNA makeup.

Near-infrared remotely triggered drug-release strategies for cancer treatment

Remotely controlled, localized drug delivery is highly desirable for potentially minimizing the systemic toxicity induced by the administration of typically hydrophobic chemotherapy drugs by conventional means. Nanoparticle-based drug delivery systems provide a highly promising approach for localized drug delivery, and are an emerging field of interest in cancer treatment. Here, we demonstrate near-IR light-triggered release of two drug molecules from both DNA-based and protein-based hosts that have been conjugated to near-infrared-absorbing Au nanoshells (SiO2 core, Au shell), each forming a light-responsive drug delivery complex. We show that, depending upon the drug molecule, the type of host molecule, and the laser illumination method (continuous wave or pulsed laser), in vitro light-triggered release can be achieved with both types of nanoparticle-based complexes. Two breast cancer drugs, docetaxel and HER2-targeted lapatinib, were delivered to MDA-MB-231 and SKBR3 (overexpressing HER2) breast cancer cells and compared with release in noncancerous RAW 264.7 macrophage cells. Continuous wave laser-induced release of docetaxel from a nanoshell-based DNA host complex showed increased cell death, which also coincided with nonspecific cell death from photothermal heating. Using a femtosecond pulsed laser, lapatinib release from a nanoshell-based human serum albumin protein host complex resulted in increased cancerous cell death while noncancerous control cells were unaffected. Both methods provide spatially and temporally localized drug-release strategies that can facilitate high local concentrations of chemotherapy drugs deliverable at a specific treatment site over a specific time window, with the potential for greatly minimized side effects.