Electroreduction of Carbon Dioxide to Acetate using Heterogenized Hydrophilic Manganese Porphyrins.

The electrochemical reduction of carbon dioxide (CO2 ) to value-added chemicals is a promising strategy to mitigate climate change. Metalloporphyrins have been used as a promising class of stable and tunable catalysts for the electrochemical reduction reaction of CO2 (CO2 RR) but have been primarily restricted to single-carbon reduction products. Here, we utilize functionalized earth-abundant manganese tetraphenylporphyrin-based (Mn-TPP) molecular electrocatalysts that have been immobilized via electrografting onto a glassy carbon electrode (GCE) to convert CO2 with overall 94 % Faradaic efficiencies, with 62 % being converted to acetate. Tuning of Mn-TPP with electron-withdrawing sulfonate groups (Mn-TPPS) introduced mechanistic changes arising from the electrostatic interaction between the sulfonate groups and water molecules, resulting in better surface coverage, which facilitated higher conversion rates than the non-functionalized Mn-TPP. For Mn-TPP only carbon monoxide and formate were detected as CO2 reduction products. Density-functional theory (DFT) calculations confirm that the additional sulfonate groups could alter the C-C coupling pathway from *CO→*COH→*COH-CO to *CO→*CO-CO→*COH-CO, reducing the free energy barrier of C-C coupling in the case of Mn-TPPS. This opens a new approach to designing metalloporphyrin catalysts for two carbon products in CO2 RR.

Immobilization strategies for porphyrin-based molecular catalysts for the electroreduction of CO2.

The ever-growing level of carbon dioxide (CO2) in our atmosphere, is at once a threat and an opportunity. The development of sustainable and cost-effective pathways to convert CO2 to value-added chemicals is central to reducing its atmospheric presence. Electrochemical CO2 reduction reactions (CO2RRs) driven by renewable electricity are among the most promising techniques to utilize this abundant resource; however, in order to reach a system viable for industrial implementation, continued improvements to the design of electrocatalysts is essential to improve the economic prospects of the technology. This review summarizes recent developments in heterogeneous porphyrin-based electrocatalysts for CO2 capture and conversion. We specifically discuss the various chemical modifications necessary for different immobilization strategies, and how these choices influence catalytic properties. Although a variety of molecular catalysts have been proposed for CO2RRs, the stability and tunability of porphyrin-based catalysts make their use particularly promising in this field. We discuss the current challenges facing CO2RRs using these catalysts and our own solutions that have been pursued to address these hurdles.

A Second Generation Mn-Porphyrin Dimer with a Twisted Linker as a Potential Blood Pool Agent for MRI: Tuning the Geometry and Binding with HSA.

Blood-pool agents (BPAs) are MRI contrast agents (CAs) characterized by their long circulation in the vascular system to provide an extended time window for high-resolution MR angiography (MRA). Prolonged vascular retention, however, impedes the excretion of BPAs. Therefore, chemical strategy to regulate the balance between retention and clearance is important to reach optimal pharmacokinetics. We recently developed MnP2, the first Mn(III)-porphyrin (MnP) based BPA. MnP2 shows high T1 relaxivity (r1) and high affinity to human serum albumin (HSA) that leads to up to 48-h vascular retention in rats. However, upon albumin binding, the r1 is decreased. To modulate vascular retention time and plasma r1, a regioisomer of MnP2, m-MnP2, was synthesized. The free m-MnP2 exhibits lower r1 than that of MnP2 at magnetic fields above 2 MHz, which agrees with their relative hydrodynamic sizes. The HSA binding of m-MnP2 was evaluated using UV-Vis spectroscopy and found to have tuned-down affinity in comparison with MnP2. Upon HSA binding, the protein complex of m-MnP2 exhibits an r1 of 11.8 mM-1 s-1 at 3 T, which is higher than that of MnP2 bound to HSA. Taken together, this demonstrated the role of molecular geometry in optimizing the pharmacokinetics of albumin-targeting BPAs.

Characteristics of burn patients at a major burn center in Shanghai.

In China, burns are becoming a major cause of morbidity and mortality with large societal and economic implications. To date, there is little epidemiological data on burns in China to direct prevention efforts. This study describes the characteristics of burn patients admitted to a major burn center in Shanghai using a burn registry developed in Toronto, Canada. A retrospective review of burn patients discharged from the Shanghai's Rui Jin Hospital Burn Unit, between March 1st 2002 and April 30th 2003, was conducted. Of 527 patients discharged, 307 were acute burn patients and 302 (98.4%) had complete data to be included in the study. There were 214 (71%) males and 88 (29%) females with a male to female ratio of 2.4:1. The median age was 30 years, and the median total body surface area burned was 10%. The majority of burns occurred at work (58%), and the most frequent etiology was flames (39%) followed by scalds (31%) and contact with hot objects (15%). Sixteen (5%) patients had inhalation injury and six (2%) patients died. There were 70 (23%) children (0-14 years), 221 (73%) adults (15-59 years) and 11 (4%) seniors (60 years and above). Children had more scald burns (83%) and the majority (83%) occurred at home. Adults had more flame burns (46%) and the majority (79%) were work-related injuries. Seniors had more flame burns (73%) and the majority (55%) occurred in domestic incidents. Seniors had deeper burns (13%, p=0.005), required more escharotomies (55%, p=0.002), required more operations (2, p=0.051) and had higher mortality (36%, p<0.001) than other age groups. These results provide compelling evidence for performing population-based studies to identify risk factors that are susceptible to modification in each age group.

Neuroprotective effects of M826, a reversible caspase-3 inhibitor, in the rat malonate model of Huntington's disease.

1. Caspases, key enzymes in the apoptosis pathway, have been detected in the brain of HD patients and in animal models of the disease. In the present study, we investigated the neuroprotective properties of a new, reversible, caspase-3-specific inhibitor, M826 (3-([(2S)-2-[5-tert-butyl-3-[[(4-methyl-1,2,5-oxadiazol-3-yl)methyl]amino]-2-oxopyrazin-1(2H)-yl]butanoyl]amino)-5-[hexyl(methyl)amino]-4-oxopentanoic acid), in a rat malonate model of HD. 2. Pharmacokinetic and autoradiography studies after intrastriatal (i.str.) injection of 1.5 nmol of M826 or its tritiated analogue [(3)H]M826 indicated that the compound diffused within the entire striatum. The elimination half-life (T(1/2)) of M826 in the rat striatum was 3 h. 3. I.str. injection of 1.5 nmol of M826 10 min after malonate infusion induced a significant reduction (66%) in the number of neurones expressing active caspase-3 in the ipsilateral striatum. 4. Inhibition of active caspase-3 translated into a significant but moderate reduction (39%) of the lesion volume, and of cell death (24%), 24 h after injury. The efficacy of M826 at inhibiting cell death was comparable to that of the noncompetitive NMDA receptor antagonist MK801. 5. These data provide in vivo proof-of-concept of the neuroprotective effects of reversible caspase-3 inhibitors in a model of malonate-induced striatal injury in the adult rat.

The impact of Asian descent on the incidence of acquired severe aplastic anaemia in children.

Previous studies have suggested an increased incidence of acquired severe aplastic anaemia in Asian populations. We evaluated the incidence of aplastic anaemia in people of Asian descent, using a well-defined paediatric (0-14 years) population in British Columbia, Canada to minimize environmental factors. The incidence in children of East/South-east Asian descent (6.9/million/year) and South Asian (East Indian) descent (7.3/million/year) was higher than for those of White/mixed ethnic descent (1.7/million/year). There appeared to be no contribution by environmental factors. This study shows that Asian children have an increased incidence of severe aplastic anaemia possibly as a result of a genetic predisposition.