The chemical conversion of CO2 into value-added products is the key technology to realize a carbon-neutral society. One representative example of such conversion is the reverse water-gas shift reaction, which produces CO from CO2. However, the activity is insufficient at ambient pressure and lower temperatures (<600 °C), making it a highly energy-intensive and impractical process. Herein, we report indium oxide nanofibers modified with palladium catalysts that exhibit significantly potent redox activities toward the reduction of CO2 splitting via chemical looping. In particular, we uncover that the doped palladium cations are selectively reduced and precipitated onto the host oxide surface as metallic nanoparticles. These catalytic gems formed operando make In2O3 lattice oxygen more redox-active in H2 and CO2 environments. As a result, the composite nanofiber catalysts demonstrate the reverse water-gas shift reaction via chemical looping at record-low temperatures (≤350 °C), while also imparting high activities (CO2 conversion: 45%). Altogether, our findings expand the viability of CO2 splitting at lower temperatures and provide design principles for indium oxide-based catalysts for CO2 conversion.

While cross-linked hemoglobin tetramers are functional acellular oxygen carriers, their ability to scavenge endogenous nitric oxide (NO) by endothelial pore penetration results in adverse cardiovascular effects. Animal studies established that cross-linked human hemoglobins, chemically joined into a double protein, avoid NO scavenging, presumably due to their larger size preventing penetration into endothelial regions that produce NO. In the present report, we utilize azide-containing acyl phosphate reagents to form cross-linked hemoglobins then bio-orthogonally click-couple them with a bis-alkyne (CuAAC). The production of these larger oxygen-carrying hemoglobin conjugates is obtained in high yields through subunit-specific cross-linking between each βLys82 ε-amino group. The methyl phosphate leaving groups provide electrostatically induced β-subunit site-selectivity, producing azido-cross-linked hemoglobin that undergoes highly efficient CuAAC compared with previous cross-linkers. The acyl phosphates also efficiently cross-link both T-state and R-state hemoglobin. The resulting bis- and tris-tetrameric hemoglobin conjugates exhibit oxygen affinity and cooperativity that are comparable to those of the native protein. The hemoglobin derivatives from the process we describe can function as sources of oxygen in biomedical applications, such as in ex-vivo donor organ perfusion.

BACKGROUND: Hypoxia is a detrimental factor in solid tumors, leading to aggressiveness and therapy resistance. OMX, a tunable oxygen carrier from the heme nitric oxide/oxygen-binding (H-NOX) protein family, has the potential to reduce tumor hypoxia. [18F]Fluoromisonidazole ([18F]FMISO) positron emission tomography (PET) is the most widely used and investigated method for non-invasive imaging of tumor hypoxia. In this study, we used [18F]FMISO PET/CT (computed tomography) to assess the effect of OMX on tumor hypoxia in spontaneous canine tumors.
RESULTS: Thirteen canine patients with various tumors (n = 14) were randomly divided into blocks of two, with the treatment groups alternating between receiving intratumoral (IT) OMX injection (OMX IT group) and intravenous (IV) OMX injection (OMX IV group). Tumors were regarded as hypoxic if maximum tumor-to-muscle ratio (TMRmax) was greater than 1.4. In addition, hypoxic volume (HV) was defined as the region with tumor-to-muscle ratio greater than 1.4 on [18F]FMISO PET images. Hypoxia was detected in 6/7 tumors in the OMX IT group and 5/7 tumors in the OMX IV injection group. Although there was no significant difference in baseline hypoxia between the OMX IT and IV groups, the two groups showed different responses to OMX. In the OMX IV group, hypoxic tumors (n = 5) exhibited significant reductions in tumor hypoxia, as indicated by decreased TMRmax and HV in [18F]FMISO PET imaging after treatment. In contrast, hypoxic tumors in the OMX IT group (n = 6) displayed a significant increase in [18F]FMISO uptake and variable changes in TMRmax and HV.
CONCLUSIONS: [18F]FMISO PET/CT imaging presents a promising non-invasive procedure for monitoring tumor hypoxia and assessing the efficacy of hypoxia-modulating therapies in canine patients. OMX has shown promising outcomes in reducing tumor hypoxia, especially when administered intravenously, as evident from reductions in both TMRmax and HV in [18F]FMISO PET imaging.

Oxygen therapeutics have a range of applications in transfusion medicine and disease treatment. Synthetic molecules and all-natural or semi-synthetic hemoglobin-based oxygen carriers (HBOCs) have seen success as potential circulating oxygen carriers. However, many early HBOC products stalled in development due to side effects from excess hemoglobin in the blood stream and hemoglobin entering the tissue. To overcome these issues, research has focused on increasing the molecular diameter of hemoglobin by polymerizing hemoglobin molecules or encapsulating hemoglobin in liposomal carriers. This work leverages the properties of silk fibroin, a cytocompatible and non-thrombogenic biopolymer, known to entrap protein-based cargo, to engineer a fully protein-based oxygen carrier. Herein, an all-aqueous solvent evaporation technique was used to form silk particles via phase separation from a bulk polyvinyl alcohol phase (PVA). Particles size was tuned, and particles were formed with and without hemoglobin. The encapsulation efficiency and ferrous state of hemoglobin were analyzed, resulting in 60% encapsulation efficiency and a maximum of 20% ferric hemoglobin, yielding 100 µg/mL active hemoglobin in certain sfHBOC formulations. The system did not elicit a strong inflammation response in vitro, demonstrating the potential for this particle system to serve as an injectable HBOC.

Pantoea alhagi NX-11 exopolysaccharide (PAPS) is a novel microbial biostimulant that enhances crop resistance to salt and drought stress. It is biodegradable and holds promising applications in improving agricultural yield and efficiency. However, the fermentation process of PAPS exhibits a high viscosity due to low oxygen transfer efficiency, which hinders yield improvement and downstream processing. This study aimed to investigate the effects of seven oxygen carriers (Span 80, Span 20, Tween 80, Tween 20, glycerin, olive oil, and soybean oil) on fermentation yield. The results showed that the addition of 0.5% (V/V) Tween 20 significantly enhanced the production of PAPS. Moreover, the introduction of 0.5% (V/V) Tween 20 in a 7.5 L fermenter resulted in a PAPS titer of (16.85±0.50) g/L, which was 17.70% higher than that of the control group. Furthermore, the rheological characterization and the microstructure analysis of the polysaccharide products revealed that the characteristic structure of polysaccharides remained unchanged in the oxygen carrier treated group, but their viscosity increased. These findings may facilitate enhancing the biosynthesis efficiency of other polymer products.

Renal ex vivo normothermic machine perfusion (NMP) is under development as an assessment tool for high-risk kidney grafts and as a means of achieving more physiologically accurate organ preservation. On-going hemolysis has been reported during NMP, as this technique relies on red blood cells for oxygen delivery. In this study, we confirm the occurrence of progressive hemolysis during 6-hour kidney NMP. NMP-associated erythrostasis in the glomeruli and in peri-glomerular vascular networks points to an interaction between the red blood cells and the graft. Continuous hemolysis resulted in prooxidative changes in the perfusate, which could be quenched by addition of fresh frozen plasma. In a cell-based system, this hemolysis induced redox stress and exhibited toxic effects at high concentrations. These findings highlight the need for a more refined oxygen carrier in the context of renal NMP.

This is a study on a simple solution of chemically prepared small chemical molecules of synthetic enzymes: catalase, superoxide dismutase, and carbonic anhydrase (CAT, SOD, and CA). We carried out a study to see if these synthetic enzymes can replace the natural enzymes (CAT, SOD, and CA) and avoid the need for the complicated cross-linking of natural enzymes to PolyHb to form PolyHb-CAT-SOD-CA. We compared the effect a solution of these three synthetic enzymes has on the viability of warm-ischemic hepatocytes that were exposed to nitrogen for 1 h at 37°C. PolyHb significantly increased the viability. The three synthetic enzymes themselves also significantly increased the viability. The use of both PolyHb and the three synthetic enzymes resulted in an additive effect in the recovery of viability. Increasing the concentration of the synthetic enzymes resulted in further increase in the effect due to the synthetic enzymes. Implications: In addition to PolyHb, there are a number of other HBOC oxygen carriers. However, only Biopure\'s HBOC product has received regulatory approval, but only in Russia and South Africa. None of the HBOCs has received regulatory approval by other countries. If regulatory agencies require HBOCs to have antioxidant or CO2 transport properties, all that is needed is to add or inject the solution of synthetic enzymes as a separate component.

Perfluorocarbon (PFC) are biocompatible compounds, chemically and biologically inert, and lacks toxicity as oxygen carriers. PFCs nanoemulsions and nanoparticles (NPs) are highly used in diagnostic imaging and enable novel imaging technology in clinical imaging modalities to notice and image pathological and physiological alterations. Therapeutics with PFCs such as the innovative approach to preventing thrombus formation, PFC nanodroplets utilized in ultrasonic medication delivery in arthritis, or PFC-based NPs such as Perfluortributylamine (PFTBA), Pentafluorophenyl (PFP), Perfluorohexan (PFH), Perfluorooctyl bromide (PFOB), and others, recently become renowned for oxygenating tumors and enhancing the effects of anticancer treatments as oxygen carriers for tumor hypoxia. In this review, we will discuss the recent advancements that have been made in PFC\'s applications in theranostic (therapeutics and diagnostics) as well as assess the benefits and drawbacks of these applications.

The inert atmosphere in chemical looping (CL) technology can considerably inhibit the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans during the thermal treatment of polyvinyl chloride plastic (PVC) waste. In this study, PVC was innovatively converted to dechlorinated fuel gas via CL gasification under a high reaction temperature (RT) and the inert atmosphere by applying an unmodified bauxite residue (BR) as both a dechlorination agent and oxygen carrier. The dechlorination efficiency reached 49.98% at an oxygen ratio of only 0.1. Furthermore, a moderate RT (750 °C in this study) and an increased oxygen ratio enhanced the dechlorination effect. The highest dechlorination efficiency (92.12%) was achieved at an oxygen ratio of 0.6. Iron oxides in BR improved the generation of syngas from CL reactions. The yields of the effective gases (CH4, H2, and CO) increased by 57.13% to 0.121 Nm3/kg with an increase in oxygen ratio from 0 to 0.6. A high RT improved the production of the effective gases (an 809.39% increase to 0.344 Nm3/kg from 600 to 900 °C). Energy-dispersive spectroscopy and X-ray diffraction were used to study the mechanism, and formation of NaCl and Fe3O4 was observed on the reacted BR, indicating the successful adsorption of Cl and its capability as an oxygen carrier. Therefore, BR eliminated Cl in situ and enhanced the generation of value-added syngas, thereby achieving efficient PVC conversion.

At present, the production of propylene falls short of the demand, and, as the global economy grows, the demand for propylene is anticipated to increase even further. As such, there is an urgent requirement to identify a novel method for producing propylene that is both practical and reliable. The primary approaches for preparing propylene are anaerobic and oxidative dehydrogenation, both of which present issues that are challenging to overcome. In contrast, chemical looping oxidative dehydrogenation circumvents the limitations of the aforementioned methods, and the performance of the oxygen carrier cycle in this method is superior and meets the criteria for industrialization. Consequently, there is considerable potential for the development of propylene production by means of chemical looping oxidative dehydrogenation. This paper provides a review of the catalysts and oxygen carriers employed in anaerobic dehydrogenation, oxidative dehydrogenation, and chemical looping oxidative dehydrogenation. Additionally, it outlines current directions and future opportunities for the advancement of oxygen carriers.