Triggered by the resounding success of cisplatin, the past decades have seen tremendous efforts to produce clinically beneficial analogues. The recent achievement of oxaliplatin for the treatment of colon cancer should, however, not belie the imbalance between a plethora of investigated complexes and a very small number of clinically approved platinum drugs. Strategies opening up new avenues are increasingly being sought using complexes of metals other than platinum such as ruthenium or gallium. Based on the chemical differences between these metals, the spectrum of molecular mechanisms of action and potential indications can be broadened substantially. Other approaches focus on complexes with tumour-targeting properties, thereby maximizing the impact on cancer cells and minimizing the problem of adverse side effects, and complexes with biologically active ligands.

Antitumour metal compounds: more than theme and variations

In the present study, we focused on a quick and green method to fabricate Ag, Au and Ag/Au alloy nanoparticles (NPs) using the bark extract of Guazuma ulmifolia L. Green synthesized metal NPs were characterized using different techniques, including UV-Vis spectroscopy, FT-IR, XRD, AFM and HR-TEM analyses. The production of Ag, Au and Ag/Au alloy NPs was observed monitoring color change from colorless to brown, followed by pink and dark brown, as confirmed by UV-Vis spectroscopy characteristic peaks at 436, 522 and 510nm, respectively. TEM shed light on the spherical shapes of NPs with size ranges of 10-15, 20-25 and 10-20nm. Biosynthesized NPs showed good catalytic activity reducing two organic dyes, 4-nitrophenol (4-NP) and Congo red (CR). UV-vis spectroscopy, fluorescence, circular dichroism spectroscopy and viscosity analyses were used to investigate the NP binding with calf thymus DNA. The binding constant of NPs with DNA calculated in UV-Vis absorption studies were 1.18×104, 1.83×104 and 2.91×104M-1, respectively, indicating that NPs were able to bind DNA with variable binding affinity: Ag/Au alloy NPs>Ag NPs>Au NPs. Ag/Au alloy NPs also showed binding activity to bovine serum albumin (BSA) over the other NPs. Ag and Ag/Au alloy NPs exhibited good antimicrobial activity on 14 species of microbial pathogens. In addition, the cytotoxic effects of Ag/Au alloy NPs were studied on human cervical cancer cells (HeLa) using MTT assay. Overall, our work showed the promising potential of bark-synthesized Ag and Ag/Au alloy NPs as cheap sources to develop novel and safer photocatalytic, antimicrobial and anticancer agents.

Guazuma ulmifolia bark-synthesized Ag, Au and Ag/Au alloy nanoparticles: Photocatalytic potential, DNA/protein interactions, anticancer activity and toxicity against 14 species of microbial pathogens.

For analytical applications in portable sensors to be used in the point-of-need, low-cost SERS substrates using paper as a base, are an alternative In this work, SERS substrates were produced on two different types of paper: a high porosity paper (Whatman no 1); and a low porosity paper (commercially available office paper, Portucel Soporcel) Solutions containing spherical silver nanoparticles (AgNPs) and silver nanostars (AgNSs) were separately drop-casted on hydrophilic wells patterned on the papers The porosity of the paper was found to play a determinant role on the AgNP and AgNS distribution along the paper fibres, with most of the nanoparticles being retained at the illuminated surface of the office paper substrate The highest SERS enhancements were obtained for the office paper substrate, with deposited AgNSs A limit of detection for rhodamine-6G as low as 114 ± 02 pg could be achieved, with an analytical enhancement factor of ≈107 for this specific analyte The well patterning technique allowed good signal uniformity (RSD of 17%) Besides, these SERS substrates remained stable after 5 weeks of storage (RSD of 73%) Paper-induced aggregation of AgNPs was found to be a viable alternative to the classical salt-induced aggregation, to obtain a highly sensitive SERS substrates

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Office paper decorated with silver nanostars - an alternative cost effective platform for trace analyte detection by SERS.

Organotin(IV) complexes derived from Schiff base N'-[(1E)-(2-hydroxy-3-methoxyphenyl)methylidene]pyridine-4-carbohydrazone: synthesis, in vitro cytotoxicities and DNA/BSA interaction.

Organotin(IV) complexes derived from hydrazone Schiff base: Synthesis, crystal structure, in vitro cytotoxicity and DNA/BSA interactions

Synthesis, structural characterization, in vitro cytotoxicities, DNA-binding and BSA interaction of diorganotin (IV) complexes derived from hydrazone Schiff base

Citrate-reduced silver nanoparticles (Ag-NPs) are used extensively for surface-enhanced Raman scattering (SERS) studies, but are typically found to aggregate using an aggregation agent. This study is aimed at developing a simple, stable, and reproducible aggregated method for Ag-NPs without any aggregation agents in aqueous solutions. The aggregation is induced by the process of centrifugation, water washing and ultrasonication. A mechanism based on the nonuniform distribution of capping ligands is proposed to account for the aggregated structure formation. UV-Vis-NIR extinction spectra and TEM allowed us to identify the existence of Ag-NPs aggregation. Further, due to the polydisperse mixture of Ag-NPs (20~65 nm) used in the present work, Ag-NPs are aggregated closely, which contribute to the observation of low-concentration SERS from the residual citrate layer or even the single-molecule SERS of R6Gon aggregation. After the evaporation of droplet of Ag-NPs aggregation on the Si substrate, citrate or R6Gcould also be detected but with marked redor blue-shifts.

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Nonuniform Distribution of Capping Ligands Promoting Aggregation of Silver Nanoparticles for Use as a Substrate for SERS

Coordination geometry of monomeric, dimeric and polymeric organotin(IV) compounds constructed from 5-bromopyridine-2-carboxylic acid and mono-, di- or tri-organotin precursors

Yanwei Zhang

Papers

Synthesis, structural characterization, in vitro cytotoxicities, DNA-binding and BSA interaction of diorganotin (IV) complexes derived from hydrazone Schiff base

Nonuniform Distribution of Capping Ligands Promoting Aggregation of Silver Nanoparticles for Use as a Substrate for SERS

Coordination geometry of monomeric, dimeric and polymeric organotin(IV) compounds constructed from 5-bromopyridine-2-carboxylic acid and mono-, di- or tri-organotin precursors