Interactions of binuclear ruthenium(II) complexes with oligonucleotides in hydrogel matrix: enantioselective threading intercalation into GC context

Synthesis of fluorescent AuNCs with RNA as template

Although nucleic acids have been widely used as templates for the synthesis of nanomaterials, the synthesis of RNA-templated gold nanoclusters (AuNCs) has not been explored. In this work, we developed a simple strategy for synthesis of RNA-templated fluorescent AuNCs. We first evaluated the adsorption of different nucleoside monophosphates (NMP) on gold atoms. Our density function theory simulation and isothermal titration calorimetry measurements demonstrated that adenosine monophosphate (AMP) is a superior gold binder than other NMPs or deoxyadenosine monophosphate. Afterwards, NMP-templated synthesis of AuNCs was conducted in various pH environments, and our results indicated that bright green light-emitting AMP-templated AuNCs can be obtained at pH ∼6.0. In order to study the synthesis mechanism of AuNCs, we investigated the effects of reducing agent type and addition time, and the negative charge carried by template nucleotides on the fluorescence of AuNCs. Finally, we extended the template AMP into RNA hairpin structure, the fluorescence intensity was the highest when the cyclic bases were poly 16 A. This study opens new routes to synthesize fluorescent AuNCs using RNA templates.

Cryogenic Photoelectron Spectroscopic and Theoretical Study of the Electronic and Geometric Structures of Undercoordinated Osmium Chloride Anions OsCln- (n = 3-5)

A series of anionic transition metal halides, OsCln- (n = 3-5), have been investigated using a newly developed, home-constructed, cryogenic anion cluster photoelectron spectroscopy. The target anionic species are generated through collision-induced dissociation in a two-stage ion funnel. The measured vertical detachment energies (VDEs) are 3.48, 4.54, and 4.81 eV for n = 3, 4, and 5, respectively. Density functional theory calculations at the B3LYP-D3(BJ)//aug-cc-pVTZ(-pp) level predict the lowest energy structures of the atomic form of OsCln- (n = 3-5) to be a quintet triangle, quartet square, and quintet square-based pyramid, respectively. The CCSD(T)-calculated VDEs and corresponding adiabatic detachment energies agree well with our experimental measurements. Analysis of the corresponding frontier molecular orbitals and charge density differences suggests that the d-orbitals of the transition metal Os play a primary role in the single-photon detachment processes, and the detached electrons originating from different molecular orbitals are distinguishable.

Polyethylene glycols affect electron transfer rate in phenosafranin-DNA complex

Long distance electron transfer (ET) between small ligands and DNA is a much studied phenomenon and is principally believed to occur through electron (or hole) hopping. Several studies have been carried out in aqueous environments while in real biological milieu the DNA molecules experience a more dense and heterogeneous environment containing otherwise indifferent molecular crowders. It is therefore expected that the ET could get modified in the presence of crowding agent and to investigate that we have made elaborate studies on steady state and time-resolved (picosecond (ps) and femtosecond (fs)-resolved) emission properties of a phenosafranine (PSF) intercalated to calf thymus (CT) DNA in the presence of ethylene glycol (EG) and polyethylene glycols (PEG) of different chain lengths (PEG 200, 400 and 1000). The emission of PSF gets considerably quenched when intercalated to DNA; the quenching is released when PEGs are added into it. The structural integrity of the CT DNA has been established using circular dichroism spectroscopy. CD measurements have evidenced only marginal changes in the DNA structure upon the addition of PEGs. ps-Resolved fluorescence measurements show significant decrease in the contribution of the DNA induced quenched time-constant of PSF upon the addition of PEGs, however, fs-resolved measurements show less noticeable changes in the time constants. Our study shows that the electron hopping rate through the guanine base in DNA core remains unaffected whereas the 'through space' electron transfer process does get affected in the presence of molecular crowders.

Anti-ROR1 scFv-EndoG as a Novel Anti-Cancer Therapeutic Drug

Aim: Immunotoxins are proteins that consist of an antibody fragment linked to a toxin, used as agents for targeted therapy of cancers. Although the most potent immunotoxins are made from bacterial and plant toxins, obstacles which contribute to poor responses are immunogenicity in patients and rapid development of neutralizing antibodies. In the present study we proposed a new therapeutic immunotoxin for targeted cancer therapy of ROR1 expressing cancers: an anti ROR1 single chain fragment variable antibody (scFv)-endonuclease G (anti ROR1 scFv-EndoG). Methods: The three-dimensional structure of anti ROR1 scFv-EndoG protein was modeled and structure validation tools were employed to confirm the accuracy and reliability of the developed model. In addition, stability and integrity of the model were assessed by molecular dynamic (MD) simulation. Results: All results suggested the protein model to be acceptable and of good quality. Conclusions: Anti-ROR1 scFv-EndoG would be expected to bind to the ROR1 extracellular domain by its scFv portion and selectively deliver non-immunogenic human endonuclease G enzyme as an end-stage apoptosis molecule into ROR1-expressing cancer cells and lead rapidly to apoptosis. We believe that anti ROR1 and other anti-tumor antigen scFv-EndoG forms may be helpful for cancer therapy.

Thermodynamic investigation of interaction between [(η6-p-cymene) RuII(acetone-N4-phenylthiosemicarbazone)Cl]Cl anticancer drug and human serum albumin: spectroscopic and electrochemical studies

In this contribution, the interaction between [(η (6)-p-cymene)Ru(II)(acetone-N (4)-phenylthiosemicarbazone)Cl]Cl (Ru-TSC) anticancer drug and human serum albumin (HSA) was investigated by spectroscopic and electrochemical techniques. The fluorescence spectra results indicated that Ru-TSC anticancer drug could quench the intrinsic fluorescence of HSA through dynamic quenching mode. The calculated corresponding activation energy of the interaction between Ru-TSC anticancer drug and HSA was 35.62 kJ mol(-1). The distance between HSA and Ru-TSC anticancer drug was obtained according to fluorescence resonance energy transfer. The results of synchronous fluorescence spectra, three-dimensional fluorescence spectra, Fourier transform infrared spectroscopy (FTIR) spectra, and circular dichroism (CD) spectra indicated that the microenvironment and the conformation of HSA were all changed in the presence of Ru-TSC anticancer drug. The results of cyclic voltammetry further validated the interaction between Ru-TSC and HSA. These results indicated that the biological activity of HSA was affected by Ru-TSC anticancer drug dramatically.

Thermodynamic investigation of the interaction between the [(η6-p-cymene)Ru(benzaldehyde-N4-phenylthiosemicarbazone)Cl]Cl anticancer drug and ctDNA: multispectroscopic and electrochemical studies

The interaction between the [(η⁶-p-cymene)Ru(benzaldehyde-N⁴-phenylthiosemicarbazone)Cl]Cl anticancer drug and ctDNA was systematically investigated by multispectroscopic and electrochemical studies.

A sensitive quantum dots-based "OFF-ON" fluorescent sensor for ruthenium anticancer drugs and ctDNA

In this contribution, a simple and sensitive fluorescent sensor for the determination of both the three ruthenium anticancer drugs (1 to 3) and calf thymus DNA (ctDNA) was established based on the CdTe quantum dots (QDs) fluorescence "OFF-ON" mode. Under the experimental conditions, the fluorescence of CdTe QDs can be effectively quenched by ruthenium anticancer drugs because of the surface binding of these drugs on CdTe QDs and the subsequent photoinduced electron transfer (PET) process from CdTe QDs to ruthenium anticancer drugs, which render the system into fluorescence "OFF" status. The system can then be "ON" after the addition of ctDNA which brought the restoration of CdTe QDs fluorescence intensity, since ruthenium anticancer drugs broke away from the surface of CdTe QDs and inserted into double helix structure of ctDNA. The fluorescence quenching effect of the CdTe QDs-ruthenium anticancer drugs systems was mainly concentration dependent, which could be used to detect three ruthenium anticancer drugs. The limits of detection were 5.5 × 10(-8) M for ruthenium anticancer drug 1, 7.0 × 10(-8) M for ruthenium anticancer drug 2, and 7.9× 10(-8) M for ruthenium anticancer drug 3, respectively. The relative restored fluorescence intensity was directly proportional to the concentration of ctDNA in the range of 1.0 × 10(-8) M ∼ 3.0 × 10(-7) M, with a correlation coefficient (R) of 0.9983 and a limit of detection of 1.1 × 10(-9) M. The relative standard deviation (RSD) for 1.5 × 10(-7) M ctDNA was 1.5% (n = 5). There was almost no interference to some common chemical compounds, nucleotides, amino acids, and proteins. The proposed method was applied to the determination of ctDNA in three synthetic samples with satisfactory results. The possible reaction mechanism of CdTe QDs fluorescence "OFF-ON" was further investigated. This simple and sensitive approach possessed some potential applications in the investigation of interaction between drug molecules and DNA.

Combined spectroscopy and cyclic voltammetry investigates the interaction between [(η6-p-cymene)Ru(benzaldehyde-N(4)-phenylthiosemicarbazone)Cl]Cl anticancer drug and human serum albumin

The interaction between Ru anticancer drug and HSA was investigated systematically under physiological conditions.