Author Archive

Osmium complex for photochemotherapy: a new way to win with hypoxic tumors

By Damayanti Bagchi, Guest Web Writer

Hypoxia, an event of inadequate oxygen supply to solid tumor, is related to aggressive propagation of malignancy by altering cancer cell metabolism. It also induces resistance to standard cancer chemotherapeutics and requires ‘out of the box’ thinking to deal with, often termed as alternative strategies.

Photodynamic therapy (PDT) uses a light activated chemical, termed photosensitizer (PS), which can behave like a drug only in the presence of specific light. The photon energy could excite the PS molecule that can produce reactive oxygen species (ROS) which in turn destroys cancer cells. PDT requires an oxygen-filled environment to be effective, which restricts its application in hypoxic tumors. Alternatively, photochemotherapy (PCT) follows a similar mechanism to PDT, and differs only by exploiting an oxygen-independent reaction pathway and hence could be used under hypoxic conditions.

The search for new effective PCT agents needs optimization in a lot of parameters given the stability of the compound, and sensitivity to different physical (light, heat) and chemical (pH, tumor micro-environment) conditions. The replication of hypoxic tumor conditions in a lab-based cell culture set up is quite challenging. Despite all of these tricks, scientists from the US, Canada and Italy came up with a new class of heavy-metal based photo-chemo agents, in a cross-country collaborative scientific investigation.

The researchers synthesized a range of Os(II)-oligothienyl-appended metal-ligand complexes that can produce highly effective cytotoxicity in hypoxia, through light- induced electron transfer reactions via triplet intra-ligand charge transfer excited states. The novel complex is defined as [Os(phen)2(IP-nT)]Cl2, where phen =1,10- phenanthroline, IP = imidazo[4,5-f][1,10]phenanthroline, and nT = thiophenes of varying chain lengths n (n = 0–4). Scheme 1 shows details of the structural variety.

Scheme 1: Molecular structures of reference compound [Os(phen)3]2+ and Os-0T–Os-4T.

Rigorous computational investigation using quantum mechanical calculations indicates all the Os(II) complexes have the requisite triplet state energies to sensitize ROS production by Type II energy transfer pathway but the actual effect in cells would likely depend on the local concentrations of these complexes and the redox environment. The detailed experimental photophysical studies reveal more on the structure-activity relationship of the complexes. All these complexes show broad absorption in the visible light region (400-550 nm) and weaker absorption in the near-infra red (NIR 700 nm) range. The excited state absorption spectra clearly show the difference in the long-lived triplet state with increasing conjugation with the addition of ligands (n=1-4). Figure 1 depicts the different photophysical pathways present in the complexes. The extended conjugation in Os-4T provides the longest triplet excited state lifetimes (3–4ms and 14–16ms), which suggests it’s superior ROS generation capability over the other complexes.

Figure 1: Jablonski diagrams depicting the proposed decay pathways in (a) Os-1T, (b) Os-3T, and (c) Os-4T. UV-vis spectra of Os-nT complexes at room temperature in acetonitrile (d). Transient absorption profiles for (e) Os-0T–Os-2T, and (f) Os-3T and Os-4T.

The complex Os-4T provides remarkable photocytotoxicity in human melanoma cells and the activity is dependent on the wavelength of the light source used. Authors reported an exceedingly high phototherapeutic index (PI) of 6500 (a value of more than 100 is highly active) under red light irradiation. The significant activity attained using NIR light expands the potential activity of the complex Os-4T via implication of the NIR biological window I. However, the light dependency of cytotoxicity changes in hypoxic conditions in which PI is found to be 90. The potential toxicity of the heavy metal-based complex is also investigated, and the complex is found to be safe up to 200 mg/kg doses in mice, which is pretty high compare to other PCT agents. The study gives the first insight into Os-based photo-chemo agents with remarkably high activity in both oxygen-rich normoxic and oxygen-deficient hypoxic conditions. Researchers are currently expanding this work and validating the effects of Os-4T in mice models and hope to proceed with clinical human trials for the eradication of the long-standing invincible problem of cancer.

To find out more, please read:

Breaking the barrier: an osmium photosensitizer with unprecedented hypoxic phototoxicity for real world photodynamic therapy

John A. Roque, III, Patrick C. Barrett, Houston D. Cole, Liubov M. Lifshits, Ge Shi, Susan Monro, David von Dohlen, Susy Kim, Nino Russo, Gagan Deep, Colin G. Cameron,* Marta E. Alberto* and Sherri A. McFarland*

Chem. Sci., 2020, 11, 9784-9806

About the blogger:

Dr Damayanti Bagchi is a postdoctoral researcher in Irene Chen’s lab at University of California, Los Angeles, United States. She obtained her PhD in Physical Chemistry from Satyendra Nath Bose National Centre for Basic Sciences, India. Her research is focused on spectroscopic studies of nano-biomaterials. She is interested in exploring light enabled therapeutics. She enjoys food and experimenting with various cuisines, which she found resembles products/ side products of chemical reactions!

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International Conference on Energy Materials and Interfaces

Last month the North East Centre for Energy Materials (NECEM) held the International Conference on Energy Materials and Interfaces in Newcastle, UK, which was sponsored by Chemical Science. The conference covered topics including flexible photovoltaics, thermoelectric devices, computational simulations of interfaces in energy capture devices, applications of 2D materials in energy capture and storage, tailored interfaces in turbines and new conc‌epts in electrical and electrochemical energy storage.

Chemical Science sponsored a poster prize, which was awarded to Stephen Campbell from Northumbria University. RSC journals Energy & Environmental Science and Sustainable Energy & Fuels also awarded poster prizes to David Alejandro Palacios Gomez from Durham Unviersity and Wei-Hsiang Lin from National Tsing Hua University.

Energy & Environmental Science poster prize winner David Alejandro Palacios Gomez, from Durham University

Sustainable Energy & Fuels poster prize winner Wei-Hsiang Lin from National Tsing Hua University

Congratulations to the prize winners from everyone at Chemical Science!

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2019 Alberta Nanosymposium

The 6th Alberta Nano Research Symposium was held earlier this year in May. The theme this year was NaNoTeCH: Celebrating the periodic table, with keynote speakers Dr Shirley Tang (University of Waterloo) and Dr Robert Carpick (University of Pennsylvania).

Chemical Science sponsored a poster prize, along with RSC journal Nanoscale Horizons. Congratulations to both of the prize winners from everyone at Chemical Science!

Taylor Lynk was awarded the Chemical Science Poster Prize

Nidhika Bhoria was awarded the Nanoscale Horizons Poster Prize

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Charge & Substrate Transport in 3D Electrocatalytic Materials, ACS Fall Meeting

Chemical Science, along with RSC journals RSC AdvancesEnergy & Environmental ScienceSustainable Energy & Fuels and Nanoscale Advances are pleased to be sponsoring the Charge & Substrate Transport in 3D Electrocatalytic Materials symposium at the ACS Fall 2019 National Meeting and Exposition in San Diego this August. It will be held at 8:30 am on Tuesday 27th in the Marina Ballroom Salon G at Marriott Marquis San Diego Marina.

Organized by Anthony Hall, Charles McCrory and V. Sara Thoi as part of the Division of Inorganic Chemistry, this symposia will be presided by Charles McCrory (University of Michigan) and feature presentations from Shelley D Minteer (University of Utah), Daniel Esposito (Columbia University), Yogesh Surendranath (MIT), Joseph Thomas Hupp (Northwestern University), Casey R Wade (Ohio State University), Amanda J Morris (Virginia Tech) as well as Charles McCrory.

 

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François Gabbaï joins Chemical Science as an Associate Editor

We are delighted to announce that Dr François Gabbaï has joined Chemical Science as our newest Associate Editor.

François Gabbaï was born in France and attended the University of Bordeaux before moving to UT Austin where he became a PhD student with Alan Cowley.  Upon completion of his Ph.D. in 1994, he joined the group of Hubert Schmidbaur at the Technical University of Munich, first as a postdoctoral fellow and later as an Habilitand.  Upon completion of his Habilitation in 1998, he moved to Texas A&M University where he now holds the Arthur E. Martell Chair of Chemistry.  His research interests revolve around the chemistry of p-block elements and late transition metals with applications in anion recognition, anion transport, and catalysis.  His is a Fellow of the American Chemical Society, a Fellow of the Royal Society of Chemistry and the recipient of the 2009 North American Dalton Lectureship. In 2016, he also received the ACS F. Albert Cotton Award in Synthetic Inorganic Chemistry.

François has selected 4 of his favourite Chemical Science articles that he has published over the years that he would like to share with you. We hope you enjoy reading them!

Large-bite diboranes for the μ(1,2) complexation of hydrazine and cyanide
C. H. Chen, F. P. Gabbaï
Chem. Sci., 2018, 9, 6210-6218
DOI: 10.1039/c8sc01877d

Fluorinated Antimony(V) Derivatives: Strong Lewis Acidic Properties and Application to the Complexation of Formaldehyde in Aqueous Solutions
D. Tofan, F. P. Gabbaï
Chem. Sci., 2016, 7, 6768-6778
DOI: 10.1039/c6sc02558g

Lewis acidic stiborafluorenes for the fluorescence turn-on sensing of fluoride in drinking water at ppm concentrations
M. Hirai, F. P. Gabbaï
Chem. Sci., 2014, 5, 1886-1893
DOI: 10.1039/c4sc00343h

Lewis acid enhancement by juxtaposition with an onium ion: the case of a mercury stibonium complex
T.-P. Lin, R. C. Nelson, T. Wu, J. T. Miller, F. P. Gabbaï
Chem. Sci., 2012, 3, 1128-1136
DOI: 10.1039/c2sc00904h

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7th UK Solar Fuels Network Symposium

The 7th UK Solar Fuels Network Symposium was held at the University of Cambridge, UK on 28th – 29th February 2019. The meeting was chaired by Professor Erwin Reisner, director of the Solar Fuels Network. Chemical Science were proud to sponsor the meeting, alongside Energy & Environmental Science and Sustainable Energy & Fuels, which are other Royal Society of Chemistry journals.

The meeting was an opportunity to bring together members of the Solar Fuels Network to meet up and discuss the latest advances in the field of solar-driven fuels research and provided an excellent opportunity for interaction with the rapidly expanding network of Solar Fuels researchers in the UK and beyond. The main meeting was followed by a half day post-graduate symposium at which PhD students and early career researchers had the opportunity to present their work. This meeting made up part of a larger ‘Solar Fuels Week’, taking place after the Artificial Photosynthesis Faraday Discussion and the Doppler Symposium.

Chemical Science Assistant Editor Carri Cotton was in attendance to meet with the delegates and represent the Royal Society of Chemistry. She also helped present a talk prize on behalf of Chemical Science and some poster prizes on behalf of Energy & Environmental Science and Sustainable Energy & Fuels:

  • Chemical Science talk prize winner: Katarzyna Sokol
  • Energy & Environmental Science poster prize winner: Hui Luo
  • Sustainable Energy & Fuels poster prize winner: Alexander Kibler

Chemical Science talk prize winner, Katarzyna Sokol (left) awarded by Carri Cotton

Energy & Environmental Science and Sustainable Energy & Fuels poster prize winners Hui Luo (left) and Alexander Kibler (right)

Congratulations to all of the prize winners from everyone at Chemical Science!

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HOT Chemical Science articles for December

We are happy to present a selection of our HOT articles over the past month. To see all of our HOT referee-recommended articles from 2018, please find the collection here.

As always, Chemical Science articles are free to access.

Reaction-free and MMP-independent fluorescent probes for long-term mitochondria visualization and tracking

Ruoyao Zhang, Guangle Niu, Xuechen Li, Lifang Guo, Huamiao Zhang, Rui Yang, Yuncong Chen, Xiaoqiang Yu and Ben Zhong Tang

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC05119D, Edge Article

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Monitoring metal–amyloid-β complexation by a FRET-based probe: design, detection, and inhibitor screening

Hyuck Jin Lee, Young Geun Lee, Juhye Kang, Seung Hyun Yang, Ju Hwan Kim, Amar B.T. Ghisaidoobe, Hyo Jin Kang, Sang-Rae Lee, Mi Hee Lim and Sang J. Chung

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC04943B, Edge Article

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Fluorinated synthetic anion carriers: experimental and computational insights into membrane partitioning and transmembrane chloride transport mechanism

Michael J. Spooner, Hongyu Li, Igor Marques, Pedro M. R. Costa, Xin Wu, Ethan N. W. Howe, Nathalie Busschaert, Stephen J. Moore, Mark E. Light, David N. Sheppard, Vítor Félix and Philip A. Gale

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC05155K, Edge Article

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How machine learning can assist the interpretation of ab initio molecular dynamics simulations and conceptual understanding of chemistry

Florian Häse, Ignacio Fdez. Galván, Alán Aspuru-Guzik, Roland Lindh and Morgane Vacher

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC04516J, Edge Article

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Synergistic Self-Seeding in One-Dimension: a Route to Patchy and Block Comicelles with Uniform and Controllable Length

Jiangping Xu, Hang Zhou, Qing Yu, Gerald Guerin, Ian Manners and Mitchell A. Winnik

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC04705G, Edge Article

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Optical control of the antigen translocation by syntethic photo-conditional viral inhibitors

M. Braner, N. Koller, J. Knauer, V. Herbring, S. Hank, R. Wieneke and R. Tampé

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC04863K, Edge Article

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HOT Chemical Science articles for November

We are happy to present a selection of our HOT articles over the past month. To see all of our HOT referee-recommended articles from 2018, please find the collection here.

As always, Chemical Science articles are free to access.

Carbon-supported Ni nanoparticles for efficient CO2 electroreduction

Mingwen Jia, Changhyeok Choi, Tai-Sing Wu, Chen Ma, Peng Kang, Hengcong Tao, Qun Fan, Song Hong, Shizhen Liu, Yun-Liang Soo, Yousung Jung, Jieshan Qiu and Zhenyu Sun

Chem. Sci., 2018, Advance Article

DOI: 10.1039/C8SC03732A, Edge Article

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Rare “Janus”-Faced {FeII7} Single-Molecule Magnet Exhibiting Intramolecular Ferromagnetic Interactions

Dimitris I Alexandropoulos, Kuduva R. Vignesh, Theocharis Stamatatos and Kim R. Dunbar

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC04384A, Edge Article

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Lytic Reactions of Drugs with Lipid Membranes

Hannah Mary Britt, Clara Antia García-Herrero, Paul W Denny, Jackie A. Mosely and John M Sanderson

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC04831B, Edge Article

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A Catalytic Antioxidant for Limiting Amyloid-Beta Peptide Aggregation and Reactive Oxygen Species Generation

Luiza M. F. Gomes, Atif Mahammed, Kathleen E Prosser, Jason R. Smith, Michael A. Silverman, Charles John Walsby, Zeev Gross and Tim Storr

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC04660C, Edge Article

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A bio-inspired approach to ligand design: folding single-chain peptoids to chelate a multimetallic cluster

Andy I. Nguyen, Ryan K. Spencer, Christopher L. Anderson and Ronald N. Zuckermann

Chem. Sci., 2018, Advance Article

DOI: 10.1039/C8SC04240C, Edge Article

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Single Ru atoms with precise coordination on a monolayer layered double hydroxide for efficient electrooxidation catalysis

Zelin Wang, Si-Min Xu, Yanqi Xu, Ling Tan, Xian Wang, Yufei Zhao, Haohong Duan and Yu-Fei Song

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC04480E, Edge Article

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Chemical Science symposia on sustainable energy

Registration is now open for our Chemical Science symposia, which are to be held in two locations in China (Harbin and Xiamen) in December.

The NSFC-RSC International Symposium on Energy Chemistry will be held in Harbin, China from 7th-9th of December, you can register now here.

The Chemical Science Symposium on Sustainable Energy will be held in Xiamen, China on 10th of December, you can register now here.

The theme of the Chemical Science Symposium will be renewable energy and sustainability, bringing together leading researchers in the field of energy science and related subjects. The primary focus will be on recent advances in sustainable and renewable energy including solar energy conversion, artificial photosynthesis, photocatalysts, water splitting, gas capture, separation and storage and fuel cells. The symposia will also cover interdisciplinary studies at the energy interface with other subjects such as the properties and applications of materials for energy and sustainability, nanotechnology, photocatalysis, photonics and biotechnology.

Chemical Science Associate Editors Vincent Artero, Kazunari Domen, James McCusker and Jihong Yu will be speaking at both symposia, and Executive Editor May Copsey will be attending.

We look forward to seeing you there!

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