Srikanta Patra

A porous trimetallic Au@Pd@Ru nanoparticle system: synthesis, characterisation and efficient dye degradation and removal

A facile room temperature one-pot synthesis of trimetallic porous Au@Pd@Ru nanoparticles (Au@Pd@RuNPs) has been developed. The trimetallic nanoparticles have been prepared by the successive sacrificial oxidation of cobalt nanoparticles (CoNPs). The average particle size of Au@Pd@RuNPs is 110 nm. The porous nature and the presence of Au, Pd and Ru have been confirmed via TEM, FE-SEM and EDS analyses. The trimetallic nanoparticles have shown excellent catalytic activity towards the reduction of p-nitrophenol and efficient degradation of various azo dyes. This has been further extended towards the removal of colour from waste water via the catalytic degradation of azo dyes. Moreover, the produced amine can be eliminated from the waste water via its sorption on an industrial solid waste dolochar.

Cyclometallated iridium complexes inducing paraptotic cell death like natural products: synthesis, structure and mechanistic aspects

Six mononuclear Ir complexes (1-6) using polypyridyl-pyrazine based ligands (L1 and L2) and {[cp*IrCl(μ-Cl)]2 and [(ppy)2Ir(μ-Cl)]2} precursors have been synthesised and characterised. Complexes 1-5 have shown potent anticancer activity against various human cancer cell lines (MCF-7, LNCap, Ishikawa, DU145, PC3 and SKOV3) while complex 6 is found to be inactive. Flow cytometry studies have established that cellular accumulation of the complexes lies in the order 2 > 1 > 5 > 4 > 3 > 6 which is in accordance with their observed cytotoxicity. No changes in the expression of the proteins like PARP, caspase 9 and beclin-1, Atg12 discard apoptosis and autophagy, respectively. Overexpression of CHOP, activation of MAPKs (P38, JNK, and ERK) and massive cytoplasmic vacuolisation collectively suggest a paraptotic mode of cell death induced by proteasomal dysfunction as well as endoplasmic reticulum and mitochondrial stress. An intimate relationship between p53, ROS production and extent of cell death has also been established using p53 wild, null and mutant type cancer cells.

Iridium Complexes as a Roadblock for DNA Polymerase during Amplification

Iridium‐based metal complexes containing polypyridyl‐pyrazine ligands show properties of DNA intercalation. They serve as roadblocks to DNA polymerase activity, thereby inhibiting the polymerization process. Upon the addition of increasing concentrations of these iridium complexes, a rapid polymerase chain reaction (PCR)‐based assay reveals the selective inhibition of the DNA polymerization process. This label‐free approach to study the inhibition of fundamental cellular processes via physical roadblock can offer an alternative route toward cancer therapy.

Preparation and mechanistic aspect of natural xanthone functionalized gold nanoparticle

Herein, a facile scale up and shape variable synthesis of gold nanoparticle (AuNP) and reaction mechanism by natural xanthone derivative (mangiferin) has been reported. Mangiferin (C19H18O11; 1,3,6,7-tetrahydroxyxanthone-C2-β-d-glucoside), a xanthone derivative is isolated from Mangifera indica L. leaves which efficiently reduces Au3+ ions to Au0 and stabilizes the formed AuNP. The structural, optical and plasmonic properties of synthesized AuNP have been investigated through different instrumental techniques like UV-Vis and FTIR spectroscopy, powder XRD, FESEM and TEM analysis. It is observed that variation of the concentration of Au3+ ions and mangiferin has a great effect on controlling size and shape of nanoparticles. The role of reaction temperature is also notable. An interesting observation is that with same concentration ratio of HAuCl4/mangiferin (0.025 mM/0.002%) at the room temperature kidney shaped AuNP is produced, whereas it is spherical at boiling temperature. Moreover, mangiferin allows high scale synthesis of AuNPs (0.025 mM to 10 mM) without changing the particles size and shape. The mechanistic investigation through UV-Vis, FTIR and GCMS analyses reveal the cleavage of glucose unit and oxidation of phenolic OH groups during AuNP formation. Non-toxicity of mangiferin conjugated AuNP on normal human breast cell line (MCF-10A) suggesting its future application as a drug delivery system and other related medicinal purposes.

Cyclometallated imidazo-phenanthroline iridium complexes and their anticancer activity

AbstractCyclometallated mononuclear iridium complexes (1–3) were synthesized using dimeric precursor [

Green synthesis of multi-metallic nanocubes

(\hbox {ppy})_{2}\hbox {Ir}^{\mathrm{III}}(\upmu \hbox {-Cl})]_{2}

Mixed-Valent Metals Bridged by a Radical Ligand : Fact or Fiction Based on Structure-Oxidation State Correlations

(ppy)2IrIII(μ-Cl)]2 and imidazo-phenanthroline-based ligands (