Ru(ii)/Os(ii)-based carbonic anhydrase inhibitors as photodynamic therapy photosensitizers for the treatment of hypoxic tumours.

Photodynamic therapy (PDT) is a medical technique for the treatment of cancer. It is based on the use of non-toxic molecules, called photosensitizers (PSs), that become toxic when irradiated with light and produce reactive oxygen specious (ROS) such as singlet oxygen (1O2). This light-induced toxicity is rather selective since the physician only targets a specific area of the body, leading to minimal side effects. Yet, a strategy to improve further the selectivity of this medical technique is to confine the delivery of the PS to cancer cells only instead of spreading it randomly throughout the body prior to light irradiation. To address this problem, we present here novel sulfonamide-based monopodal and dipodal ruthenium and osmium polypyridyl complexes capable of targeting carbonic anhydrases (CAs) that are a major target in cancer therapy. CAs are overexpressed in the membrane or cytoplasm of various cancer cells. We therefore anticipated that the accumulation of our complexes in or outside the cell prior to irradiation would improve the selectivity of the PDT treatment. We show that our complexes have a high affinity for CAs, accumulate in cancer cells overexpressing CA cells and importantly kill cancer cells under both normoxic and hypoxic conditions upon irradiation at 540 nm. More importantly, Os(ii) compounds still exhibit some phototoxicity under 740 nm irradiation under normoxic conditions. To our knowledge, this is the first description of ruthenium/osmium-based PDT PSs that are CA inhibitors for the selective treatment of cancers.

A biomimetic cerium-based biosensor for the direct visual detection of phosphate under physiological conditions.

An indicator displacement assay (IDA) was used to probe phosphate ions in an aqueous medium at neutral pH using a dinuclear cerium based complex [Ce2(HXTA)]3+. The homoleptic complex can be used to detect phosphate ions with nanomolar affinity either spectrophotometrically or with the naked-eye. To our knowledge, this is the first dinuclear cerium biomimetic IDA detection system with the highest affinity known to date for selective, naked-eye based phosphate recognition under physiological conditions (pH = 5-7) and even in pure water and complex samples such as sea water.

«La Chimie en Couleurs¼: Socially Relevant & Original Research in Chemistry in High Schools Using Modest Resources.

Teaching chemistry at high school level has the potential of playing a major role for the development of our society, in particular, to form future leaders in chemistry who will address social challenges such as the need for better healthcare, improved agricultural techniques and more efficient use of energy resources. In general, high school chemistry teaching programs tend to illustrate the great historic discoveries and glorious past of chemical research. It is hoped that this historical perspective will help to provide students with the basic understanding necessary for the development of the chemistry of tomorrow. Unfortunately, in general, the emphasis on established chemical research and on the reassuringly solid foundations of the field is ubiquitous, not only in the theoretical classes, but also in more practical aspects of teaching, such as in the 'maturity projects' of students: These small, often laboratory-oriented 'research projects' are generally limited to reproducing the scientific literature - often printed in black & white - and/or are adding minor modifications to established scientific protocols, instead of exploring the colourful world of current scientific discoveries and the excitement of pushing back the boundaries of knowledge. Practicing innovative and original research with chemistry students is therefore a challenge for the mentor of any 'maturity project'. Here, we describe the implementation of a practical program - nicknamed 'La Chimie en Couleurs' - for carrying out original research in chemistry, making science lively, colourful and vivid to students. Science that has not already been done by others before, but that students can pursue themselves and that is totally new and original. The program is taught during high-school courses and carried out by students, using inexpensive equipment, easily accessible and non-toxic chemicals and simple chemical concepts. Part of the research work was presented by students at the Swiss Chemical Society Fall Meeting and won a poster prize in the inorganic chemistry runner up category (2016). The 'La Chimie en Couleurs' program presented here shows that up-to-date and socially-relevant chemistry (not just historically relevant chemistry!) can be taught to teenagers in a creative way through the implementation of inexpensive, albeit serious, scientific research at high school level.