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Hydrogen peroxide was produced as a solar fuel from water and dioxygen using solar energy by combination of a water oxidation catalyst and a photocatalyst for two-electron reduction of O 2 in acidic aqueous solutions. Photocatalytic production of H 2 O 2 occurred under photoirradiation of [Ru II (Me 2 phen) 3 ] 2+ (Me 2 phen ¼ 4,7-dimethyl-1,10-phenanthroline) used as a photocatalyst with visible light in the presence of Ir(OH) 3 acting as a water oxidation catalyst in an O 2-saturated H 2 SO 4 aqueous solution. Photoinduced electron transfer from the excited state of [Ru II (Me 2 phen) 3 ] 2+ to O 2 results in the formation of [Ru III (Me 2 phen) 3 ] 3+ and a superoxide radical anion (O 2 _ À) which is protonated to produce H 2 O 2 via disproportionation of HO 2 _ in competition with back electron transfer (BET) from O 2 _ À to [Ru III (Me 2 phen) 3 ] 3+. [Ru III (Me 2 phen) 3 ] 3+ oxidises water with the aid of catalysis of Ir(OH) 3 to produce O 2. The photocatalytic reactivity of H 2 O 2 production was improved by replacing Ir(OH) 3 nanoparticles by [Co III (Cp*)(bpy)(H 2 O)] 2+ in the presence of Sc(NO 3) 3 in water. The optimised quantum yield of the photocatalytic H 2 O 2 production at l ¼ 450 nm was determined using a ferrioxalate actinometer to be 37%. The value of conversion efficiency from solar energy to chemical energy was also determined to be 0.25%. Broader context Photocatalytic production of hydrogen peroxide from earth-abundant water and dioxygen using solar energy as an ideally sustainable solar fuel has remained a great challenge. We report herein for the rst time photocatalytic production of hydrogen peroxide from water and dioxygen under visible light using [Ru II (Me 2 phen) 3 ] 2+ (Me 2 phen ¼ 4,7-dimethyl-1,10-phenanthroline) as a photocatalyst and Ir(OH) 3 nanoparticles or [Co III (Cp*)(bpy)(H 2 O)] 2+ (Cp* ¼ h 5-pentamethylcyclopentadienyl, bpy ¼ 2,2-bipyridine) as a water oxidation catalyst in water containing H 2 SO 4 or Sc(NO 3) 3. A high turnover number and quantum yield have been attained by combining an efficient water oxidation catalyst with a photosensitiser and a Lewis acid in water.

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Uremic toxins often accumulate in patients with compromised kidney function, like those with chronic kidney disease (CKD), leading to major clinical complications including serious illness and death. Sufficient removal of these toxins from the blood increases the efficacy of hemodialysis, as well as the survival rate, in CKD patients. Understanding the interactions between an adsorbent and the uremic toxins is critical for designing effective materials to remove these toxic compounds. Herein, we study the adsorption behavior of the uremic toxins, p-cresyl sulfate, indoxyl sulfate, and hippuric acid, in a series of zirconium-based metal−organic frameworks (MOFs). The pyrene-based MOF, NU-1000, offers the highest toxin removal efficiency of all the MOFs in this study. Other Zr-based MOFs possessing comparable surface areas and pore sizes to NU-1000 while lacking an extended aromatic system have much lower toxin removal efficiency. From single-crystal X-ray diffraction analyses assisted by density functional theory calculations, we determined that the high adsorption capacity of NU-1000 can be attributed to the highly hydrophobic adsorption sites sandwiched by two pyrene linkers and the hydroxyls and water molecules on the Zr 6 nodes, which are capable of hydrogen bonding with polar functional groups of guest molecules. Further, NU-1000 almost completely removes p-cresyl sulfate from human serum albumin, a protein that these uremic toxins bind to in the body. These results offer design principles for potential MOFs candidates for uremic toxin removal.

Peptidylprolyl-cis-trans-isomerase (PPIase) is thought to be essential for protein folding in the cell. Two forms, a and b, of PPIase and their corresponding genes were isolated from Escherichia coli cells. Despite their insensitivity to cyclosporin A (CsA), both amino acid sequences were homologous and related to that of pig cyclophilin, a protein that has PPIase activity sensitive to CsA (Takahashi et al., 1989). PPIase a is found to be identical with the E. coli ORF 190 gene product that was sequenced by Kawamukai et al. (1989) and overexpressed by Liu and Walsh (1990). It is translocated into E. coli periplasmic space with the signal sequence. PPIase b lacks a hydrophobic amino acid stretch which could serve as a signal sequence or a transmembrane domain, and it is detected mainly in the bacterial cytoplasm. These findings indicate that proteins with the ability to assist folding of various polypeptides are located on both sides of the inner membrane. Thus, we propose that the folding of some exported proteins may be catalyzed by the periplasmic proline isomerase and, in turn, that some proteins which have isomerized may not be translocated efficiently.

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Biodegradable plastics (BPs) have attracted much attention since more than a decade because they can easily be degraded by microorganisms in the environment. The development of aliphatic-aromatic co-polyesters has combined excellent mechanical properties with biodegradability and an ideal replacement for the conventional nondegradable thermoplastics. The microorganisms degrading these polyesters are widely distributed in various environments. Although various aliphatic, aromatic, and aliphatic-aromatic co-polyester-degrading microorganisms and their enzymes have been studied and characterized, there are still many groups of microorganisms and enzymes with varying properties awaiting various applications. In this review, we have reported some new microorganisms and their enzymes which could degrade various aliphatic, aromatic, as well as aliphatic-aromatic co-polyesters like poly(butylene succinate) (PBS), poly(butylene succinate)-co-(butylene adipate) (PBSA), poly(ε-caprolactone) (PCL), poly(ethylene succinate) (PES), poly(L-lactic acid) (PLA), poly(3-hydroxybutyrate) and poly(3-hydoxybutyrate-co-3-hydroxyvalterate) (PHB/PHBV), poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(butylene adipate-co-terephthalate (PBAT), poly(butylene succinate-co-terephthalate) (PBST), and poly(butylene succinate/terephthalate/isophthalate)-co-(lactate) (PBSTIL). The mechanism of degradation of aliphatic as well as aliphatic-aromatic co-polyesters has also been discussed. The degradation ability of microorganisms against various polyesters might be useful for the treatment and recycling of biodegradable wastes or bioremediation of the polyester-contaminated environments.