The synthesis and reactions of functionalised transition metal substituted paraffins.

Thesis (Ph.D.)-University of Natal, Durban, 2002.The compounds [Cp(CO)3W{(CH2)nX}] (X = Br, I; n = 3 - 6) were prepared in high yield by the reaction ofNa[Cp(CO)3W ] with Br(CH2)nBr. The bromoalkyl compounds were subsequently reacted with NaI to give the corresponding iodoalkyl complexes. The crystal structures of [Cp(CO)3W{(CH2)sI}] and [Cp(CO)3W{(CH2)3Br}] are reported for the first time. The former compound forms orthorhombic crystals in the space group P21nb and the latter forms triclinic crystals in the space group PI. Both have W-C bond lengths of2.35 A. The C-I bond length is 2.12 A; the C-Br bond length is 1.94 A. In a similar manner to the above, the compounds [Cp(CO)2(PPhiMe3 - i)Mo{(CH2)nBr}] (Cp = TJs-CsHs, n = 3, 4; i = 0 3) and [Cp*(CO)3Mo{(CH2)nBr}] (Cp* = TJs-CS(CH3)s,n = 3, 4) were prepared in medium to high yield by the reaction of the corresponding anion [Cp(CO)2(PPhjMe3-i)Mor or [Cp*(CO)3Mor with Br(CH2)nBr. The bromoalkyl compounds were subsequently reacted with NaI to give the corresponding iodoalkyl compounds [Cp(CO)2(PPhiMe3 _i)Mo{( CH2)nI}] (n = 3, 4; i = 0 - 3) and [Cp*(CO)3Mo{(CH2)nI}] (n = 3, 4) respectively. The iodoalkyl compounds were also prepared by the reaction of the corresponding anion and a,O)diiodoalkane in much lower yields. These compounds have been fully characterised and their properties are discussed. The crystal and molecular structure of [Cp(CO)2(PPh3)Mo{(CH2)3I}] is also reported, again for the first time. The compound forms crystals in the monoclinic space group P21/n; with a Mo-C bond length of 2.40 Aand a C-I bond length of 2.13 A These halogenoalkyl compounds were used as precursors to the new heterobimetallic complexes [Cp(CO)3W(CH2)nMo(CO)3Cp] n = 3 - 6; [Cp(CO)3W(CH2)nMo(COhCp*] n = 3,4; [Cp(CO)3W(CH2)nMo(CO)2(PPhiMe3_i)Cp] n = 3,4; i = 0 - 3 and [Cp(CO)2Fe(CH2)nMo(CO)2(PPhiMe3_i)Cp] n = 3,4; i = 0 - 3. The heterobimetallic complexes were prepared by the direct displacement of the iodide of a metallo-iodoalkyl complex with the appropriate anion. The complexes have been fully characterised by IR, IH NMR, 13C NMR, COSY, HETCOR or HSQC and elemental analyses. X-ray diffraction studies are for the first time reported for the complexes [Cp(CO)3W(CH2)3Mo(CO)2(PPh3)Cp] and [Cp(CO)2( PPh3)Mo(CH2)3Fe(CO)2Cp]. Both compounds form monoclinic crystals in the space group P 2I/c. The former, with a W-C bond length of2.32 Aand Mo-C bond length of2.35 Aand the latter with a Mo-C bond length of2.37 A and Fe-C bond length of2.08 A. The reactions of some of the above halogenoalkyl compounds with some simple inorganic molecules were investigated. The reactions of [Cp(CO)3W{CH2)4Br}] and [Cp(CO)2(PPhMe2)Mo{(CH2)3Br}] with silver nitrate in acetonitrile formed orange products, [Cp(CO)3W{(CH2)40N02}] and [Cp(CO)2(PPhMe2)Mo{(CH2)30N02}] respectively. The compounds [Cp(CO)3W{(CH2)sCN}], [Cp(CO)3W{(CH2)4CN}], [Cp(CO)2(PPhMe2)Mo{(CH2)3CN}], [Cp(CO)3W{(CH2)4N3}], [Cp(CO)3W{(CH2)sN3}], [Cp(CO)2(PPhMe2)Mo{(CH2)3N3}] were also obtained from various reactions using the reagents; AgCN, KCN, NaCN and NaN3. Similar reactions with molybdenum analogs gave cyclic carbene compounds. Reaction studies were also done on some of the above heterobimetallic compounds with tertiary phosphines; carbon monoxide gas and trityl salt, and thermolyses were also investigated. The reactions of PPh3 with [Cp(CO)3W{(CH2)3}MLy] {MLy = MO(CO)3Cp, MO(CO)3Cp* and MO(CO)2(PMe3)Cp} were found to be totally metalloselective, with the phosphines always attacking the expected metal site predicted by the reactions ofthe corresponding monometallic or homodinuclear alkyl species. A similar reaction involving CO with [Cp(CO)3W(CH2)3Mo(CO)3Cp] and [Cp(COhFe(CH2)3Mo(CO)2(PMe3)Cp] was also metalloselective. The reaction of [Cp(COhFe(CH2)4Mo(CO)3)Cp*] with trityl salt gave the expected complex [Cp(CO)2Fe(C4H7)Mo(CO)3)Cp*]PF6. It is believed that the structure of the trityl salt complex has the iron atom n-bonded whilst the molybdenum is cr-bonded to the butyl chain. The compounds [Cp(CO)3W(CH2)3Mo(CO)3Cp*] and [Cp(CO)2Fe(CH2)3Ru(CO)2Cp] both gave cyclopropane on thermolysis, indicating a ~elimination and reductive processes taking place. The crystal structure of [Cp(CO)3W{(CH2)3COOH}], which was obtained in one of the reaction studies, where the compound [Cp(CO)3W(CH2)3Mo(CO)2(PMe3)Cp] was reacted with excess PPh3in acetonitrile, is reported

Peptide-functionalized quantum dots for potential applications in the imaging and treatment of obesity

BACKGROUND: Obesity is a worldwide epidemic affecting millions of people. The current pharmacological treatment of obesity remains limited and ineffective due to drugs’ undesirable side effects. Hence, there is a need for novel or improved strategies for long-term therapies that will help prevent the disease progression into other chronic diseases. Nanotechnology holds the future for the treatment of obesity because of its versatility, as shown by improved drug efficiency and safety in cancer clinical trials. Nano-based drug delivery systems could potentially do the same for obesity through targeted drug delivery. This study investigated the use of peptide-functionalized quantum dots (QDs) for the imaging of prohibitin (PHB)-expressing cells in vitro and in diet-induced obese rats, which could potentially be used as nanocarriers of antiobesity drugs. METHODS: Cadmium (Cd)-based QDs were functionalized with an adipose homing peptide (AHP) and injected intravenously into lean and obese Wistar rats. Biodistribution of the QDs was analyzed by an IVIS® Lumina XR imaging system and inductively coupled plasma optical emission spectroscopy (ICP-OES). For in vitro studies, PHB-expressing (Caco-2 and MCF-7) and non-PHB-expressing (KMST-6 and CHO) cells were exposed to either unfunctionalized QDs (QD625) or AHP-functionalized QDs (AHP-QD625) and analyzed by fluorescence microscopy. RESULTS: AHP-QD625 accumulated significantly in PHB-expressing cells in vitro when compared with non-PHB-expressing cells. In vivo data indicated that QD625 accumulated mainly in the reticuloendothelial system (RES) organs, while the AHP-QD625 accumulated mostly in the white adipose tissues (WATs). CONCLUSION: AHP-functionalized QDs were successfully and selectively delivered to the PHB-expressing cells in vitro (Caco-2 and MCF-7 cells) and in the WAT vasculature in vivo. This nanotechnology-based approach could potentially be used for dual targeted drug delivery and molecular imaging of adipose tissues in obese patients in real time

Nanotechnology advances towards development of targeted-treatment for obesity

Obesity through its association with type 2 diabetes (T2D), cancer and cardiovascular diseases (CVDs), poses a serious health threat, as these diseases contribute to high mortality rates. Pharmacotherapy alone or in combination with either lifestyle modifcation or surgery, is reliable in maintaining a healthy body weight, and preventing progression to obesity-induced diseases. However, the anti-obesity drugs are limited by non-specifcity and unsustainable weight loss efects. As such, novel and improved approaches for treatment of obesity are urgently needed. Nanotechnology-based therapies are investigated as an alternative strategy that can treat obesity and be able to overcome the drawbacks associated with conventional therapies. The review presents three nanotechnology-based anti-obesity strategies that target the white adipose tissues (WATs) and its vasculature for the reversal of obesity. These include inhibition of angiogenesis in the WATs, transformation of WATs to brown adipose tissues (BATs), and photothermal lipolysis of WATs. Compared to conventional therapy, the targeted-nanosystems have high tolerability, reduced side efects, and enhanced efcacy. These efects are reproducible using various nanocarriers (liposomes, polymeric and gold nanoparticles), thus providing a proof of concept that targeted nanotherapy can be a feasible strategy that can combat obesity and prevent its comorbiditie

Nanotechnology-Based Strategies for Treatment of Obesity, Cancer and Anti-microbial Resistance: Highlights of the Department of Science and Innovation/Mintek Nanotechnology Innovation Centre Biolabels Research Node at the University of the Western Cape

Nanotechnology has recently received much interest in various fields, including medicine. South Africa (SA) was the first country in Africa to adopt the technology with the aim of enhancing the national bio-economy and global competitiveness by using innovative nanotechnology-based solutions. Since its inception in 2005 in SA, researchers have seized opportunities to increase and develop niche areas for its application in the health, energy, food, agriculture, and water sectors. We ventured into this field and have performed pioneering work on nanotechnology-based treatment strategies over the years. This perspective highlights the journey, with associated successes over the years, in order to display the impact of our nanotechnology research in health. The focus is on the nanotechnology outputs that have emanated from the Department of Science and Innovation (DSI)/Mintek Nanotechnology Innovation Centre (NIC) Biolabels Research Node (BRN) at the University of the Western Cape (UWC). BRN’s research interests were on nano-enabled materials for developing therapeutic agents, photothermal sensitizers, and targeted drug-delivery systems for treatment of chronic diseases and antimicrobial resistance

Nanotechnology-Based Strategies for Treatment of Obesity, Cancer and Anti-microbial Resistance: Highlights of the Department of Science and Innovation/Mintek Nanotechnology Innovation Centre Biolabels Research Node at the University of the Western Cape

Nanotechnology has recently received much interest in various fields, including medicine. South Africa (SA) was the first country in Africa to adopt the technology with the aim of enhancing the national bio-economy and global competitiveness by using innovative nanotechnology-based solutions. Since its inception in 2005 in SA, researchers have seized opportunities to increase and develop niche areas for its application in the health, energy, food, agriculture, and water sectors. We ventured into this field and have performed pioneering work on nanotechnology-based treatment strategies over the years. This perspective highlights the journey, with associated successes over the years, in order to display the impact of our nanotechnology research in health. The focus is on the nanotechnology outputs that have emanated from the Department of Science and Innovation (DSI)/Mintek Nanotechnology Innovation Centre (NIC) Biolabels Research Node (BRN) at the University of the Western Cape (UWC). BRN’s research interests were on nano-enabled materials for developing therapeutic agents, photothermal sensitizers, and targeted drug-delivery systems for treatment of chronic diseases and antimicrobial resistance

Biomedical Applications of Plant Extract-Synthesized Silver Nanoparticles

Silver nanoparticles (AgNPs) have attracted a lot of interest directed towards biomedical applications due in part to their outstanding anti-microbial activities. However, there have been many health-impacting concerns about their traditional synthesis methods, i.e., the chemical and physical methods. Chemical methods are commonly used and contribute to the overall toxicity of the AgNPs, while the main disadvantages of physical synthesis include high production costs and high energy consumption. The biological methods provide an economical and biocompatible option as they use microorganisms and natural products in the synthesis of AgNPs with exceptional biological properties. Plant extract-based synthesis has received a lot of attention and has been shown to resolve the limitations associated with chemical and physical methods. AgNPs synthesized using plant extracts provide a safe, cost-effective, and environment-friendly approach that produces biocompatible AgNPs with enhanced properties for use in a wide range of applications. The review focused on the use of plant-synthesized AgNPs in various biomedical applications as anti-microbial, anti-cancer, anti-inflammatory, and drug-delivery agents. The versatility and potential use of green AgNPs in the bio-medicinal sector provides an innovative alternative that can overcome the limitations of traditional systems. Thus proving green nanotechnology to be the future for medicine with continuous progress towards a healthier and safer environment by forming nanomaterials that are low- or non-toxic using a sustainable approach