Andreia Valente

Bio: Andreia Valente is an academic researcher from University of Lisbon. The author has contributed to research in topics: Ruthenium & Polymerization. The author has an hindex of 20, co-authored 48 publications receiving 1190 citations. Previous affiliations of Andreia Valente include university of lille & Centre national de la recherche scientifique.

Isoprene–Styrene Chain Shuttling Copolymerization Mediated by a Lanthanide Half‐Sandwich Complex and a Lanthanidocene: Straightforward Access to a New Type of Thermoplastic Elastomers

Abstract: A lanthanide half-sandwich complex and a ansa lanthanidocene have been assessed for isoprene–styrene chain shuttling copolymerization with n-butylethylmagnesium (BEM). In the presence of 1 equiv BEM, a fully amorphous multiblock microstructure of soft and hard segments is achieved. The microstructure consists of poly(isoprene-co-styrene) blocks, with hard blocks rich in styrene and soft blocks rich in isoprene. The composition of the blocks and the resulting glass transition temperatures (Tg) can be easily modified by changing the feed and/or the relative amount of the catalysts, highlighting a new class of thermoplastic elastomers (TPEs) with tunable transition temperatures. The materials self-organize into nanostructures in the solid state.

Catalytic Chain Transfer (co-)Polymerization: Unprecedented Polyisoprene CCG and a New Concept to Tune the Composition of a Statistical Copolymer.

Abstract: Borohydrido-halflanthanidocene/dialkylmagnesium combinations are found to be powerful catalytic systems for the chain transfer polymerization of isoprene and its copolymerization with styrene. A behavior close to a lanthanide catalyzed polyisoprene chain growth on magnesium is reported. Transmetalation is further shown to occur in the course of the statistical copolymerization of isoprene and styrene. For the same monomer feed, the amount of styrene inserted in the copolymer can be increased by a factor 3 using 10 equiv. dialkylmagnesium versus 1 in the range of our experimental conditions. Chain transfer in the course of a metal catalyzed statistical copolymerization may thus be viewed as a new and original way for the control of the composition of a copolymer.

The development of anticancer ruthenium(II) complexes: from single molecule compounds to nanomaterials

Abstract: Cancer is rapidly becoming the top killer in the world. Most of the FDA approved anticancer drugs are organic molecules, while metallodrugs are very scarce. The advent of the first metal based therapeutic agent, cisplatin, launched a new era in the application of transition metal complexes for therapeutic design. Due to their unique and versatile biochemical properties, ruthenium-based compounds have emerged as promising anti-cancer agents that serve as alternatives to cisplatin and its derivertives. Ruthenium(iii) complexes have successfully been used in clinical research and their mechanisms of anticancer action have been reported in large volumes over the past few decades. Ruthenium(ii) complexes have also attracted significant attention as anticancer candidates; however, only a few of them have been reported comprehensively. In this review, we discuss the development of ruthenium(ii) complexes as anticancer candidates and biocatalysts, including arene ruthenium complexes, polypyridyl ruthenium complexes, and ruthenium nanomaterial complexes. This review focuses on the likely mechanisms of action of ruthenium(ii)-based anticancer drugs and the relationship between their chemical structures and biological properties. This review also highlights the catalytic activity and the photoinduced activation of ruthenium(ii) complexes, their targeted delivery, and their activity in nanomaterial systems.

Antitumour metal compounds: more than theme and variations

Abstract: 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.

Metal complexes in cancer therapy - an update from drug design perspective.

Abstract: In the past, metal-based compounds were widely used in the treatment of disease conditions, but the lack of clear distinction between the therapeutic and toxic doses was a major challenge. With the discovery of cisplatin by Barnett Rosenberg in 1960, a milestone in the history of metal-based compounds used in the treatment of cancers was witnessed. This forms the foundation for the modern era of the metal-based anticancer drugs. Platinum drugs, such as cisplatin, carboplatin and oxaliplatin, are the mainstay of the metal-based compounds in the treatment of cancer, but the delay in the therapeutic accomplishment of other metal-based compounds hampered the progress of research in this field. Recently, however, there has been an upsurge of activities relying on the structural information, aimed at improving and developing other forms of metal-based compounds and nonclassical platinum complexes whose mechanism of action is distinct from known drugs such as cisplatin. In line with this, many more metal-based compounds have been synthesized by redesigning the existing chemical structure through ligand substitution or building the entire new compound with enhanced safety and cytotoxic profile. However, because of increased emphasis on the clinical relevance of metal-based complexes, a few of these drugs are currently on clinical trial and many more are awaiting ethical approval to join the trial. In this review, we seek to give an overview of previous reviews on the cytotoxic effect of metal-based complexes while focusing more on newly designed metal-based complexes and their cytotoxic effect on the cancer cell lines, as well as on new approach to metal-based drug design and molecular target in cancer therapy. We are optimistic that the concept of selective targeting remains the hope of the future in developing therapeutics that would selectively target cancer cells and leave healthy cells unharmed.

The return of a forgotten polymer : Polycaprolactone in the 21st century

Abstract: During the resorbable-polymer-boom of the 1970s and 1980s, polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices. Its popularity was soon superseded by faster resorbable polymers which had fewer perceived disadvantages associated with long term degradation (up to 3-4 years) and intracellular resorption pathways; consequently, PCL was almost forgotten for most of two decades. Recently, a resurgence of interest has propelled PCL back into the biomaterials-arena. The superior rheological and viscoelastic properties over many of its aliphatic polyester counterparts renders PCL easy to manufacture and manipulate into a large range of implants and devices. Coupled with relatively inexpensive production routes and FDA approval, this provides a promising platform for the production of longer-term degradable implants which may be manipulated physically, chemically and biologically to possess tailorable degradation kinetics to suit a specific anatomical site. This review will discuss the application of PCL as a biomaterial over the last two decades focusing on the advantages which have propagated its return into the spotlight with a particular focus on medical devices, drug delivery and tissue engineering.