Follicular dendritic cells control engulfment of apoptotic bodies by secreting Mfge8

The secreted phosphatidylserine-binding protein milk fat globule epidermal growth factor 8 (Mfge8) mediates engulfment of apoptotic germinal center B cells by tingible-body macrophages (TBMφs). Impairment of this process can contribute to autoimmunity. We show that Mfge8 is identical to the mouse follicular dendritic cell (FDC) marker FDC-M1. In bone-marrow chimeras between wild-type and Mfge8−/− mice, all splenic Mfge8 was derived from FDCs rather than TBMφs. However, Mfge8−/− TBMφs acquired and displayed Mfge8 only when embedded in Mfge8+/+ stroma, or when situated in lymph nodes draining exogenous recombinant Mfge8. These findings indicate a licensing role for FDCs in TBMφ-mediated removal of excess B cells. Lymphotoxin-deficient mice lacked FDCs and splenic Mfge8, and suffer from autoimmunity similar to Mfge8−/− mice. Hence, FDCs facilitate TBMφ-mediated corpse removal, and their malfunction may be involved in autoimmunity

Correction to "Tracking Charge Transfer to Residual Metal Clusters in Conjugated Polymers for Photocatalytic Hydrogen Evolution"

Tracking charge transfer to residual metal clusters in conjugated polymers for photocatalytic hydrogen evolution (Journal of the American Chemical Society (2020) 142:34 (14574-14587) DOI: 10.1021/jacs.0c06104) Page 14585. Appreciation for Dr. Yan-Gu Lin was inadvertently left out of the Acknowledgments. The scientific part of the paper remains unchanged. The complete correct Acknowledgments paragraph is as follows: ¦ ACKNOWLEDGMENTS M.S. is grateful to Imperial College for a President’s Ph.D. Scholarship and to the EPSRC for a Doctoral Prize Fellowship. J.R.D. and I.M. acknowledge support from KAUST (project numbers OSR-2015-CRG4-2572 and OSR-2018-CRG7- 3749.2). C.M.A., A.I.C., and R.S.S. acknowledge the Engineering and Physical Sciences Research Council (EPSRC, EP/ N004884/1). L.F. thanks the EU for a Marie Curie fellowship (658270). S.C. thanks Imperial College London for a Schro¨dinger Scholarship. R.G. is grateful to the FRQNT for a postdoctoral award and NSERC Discovery Grant funding. C.-L.C. appreciates his supervisor, Dr. Yan-Gu Lin, for his efforts on the beamtime support of XAS beamline and corresponding equipment/technical setup. All plotted data have been deposited on the open-access repository Zenodo and can be accessed via dx.doi.org/10.5281/zenodo.3932340

Correction to "Tracking Charge Transfer to Residual Metal Clusters in Conjugated Polymers for Photocatalytic Hydrogen Evolution"

Tracking charge transfer to residual metal clusters in conjugated polymers for photocatalytic hydrogen evolution (Journal of the American Chemical Society (2020) 142:34 (14574-14587) DOI: 10.1021/jacs.0c06104) Page 14585. Appreciation for Dr. Yan-Gu Lin was inadvertently left out of the Acknowledgments. The scientific part of the paper remains unchanged. The complete correct Acknowledgments paragraph is as follows: ¦ ACKNOWLEDGMENTS M.S. is grateful to Imperial College for a President’s Ph.D. Scholarship and to the EPSRC for a Doctoral Prize Fellowship. J.R.D. and I.M. acknowledge support from KAUST (project numbers OSR-2015-CRG4-2572 and OSR-2018-CRG7- 3749.2). C.M.A., A.I.C., and R.S.S. acknowledge the Engineering and Physical Sciences Research Council (EPSRC, EP/ N004884/1). L.F. thanks the EU for a Marie Curie fellowship (658270). S.C. thanks Imperial College London for a Schro¨dinger Scholarship. R.G. is grateful to the FRQNT for a postdoctoral award and NSERC Discovery Grant funding. C.-L.C. appreciates his supervisor, Dr. Yan-Gu Lin, for his efforts on the beamtime support of XAS beamline and corresponding equipment/technical setup. All plotted data have been deposited on the open-access repository Zenodo and can be accessed via dx.doi.org/10.5281/zenodo.3932340

Solar Fuel Production from Hydrogen Sulfide: An Upstream Energy Perspective

Hydrogen sulfide is readily available in vast quantities in the subsurface as a byproduct of industrial processes. Hydrogen evolution from H2S can transform this highly toxic gas into a source of green fuel. Compared to water splitting, H2S dissociation is thermodynamically more favorable. However, feasible industrial‐scale catalytic technologies are not developed yet. The recovery of valuable chemicals using carbon‐neutral photocatalytic processes can capitalize on abundant solar irradiation and advanced semiconductors. The challenge is developing photocatalysts that can efficiently operate over the long term in the harsh environment of subsurface and industry, while utilizing as much of the light source spectrum as possible and providing optimum adsorption/desorption abilities of hydrogen and sulfur‐containing intermediates. Meeting these requirements demands improved kinematic models of photocatalytic H2S decomposition to assess the effect of high temperatures, pressures, mixtures of hydrocarbons, produced water, and other contaminants. Metal sulfides‐based catalysts may be the key to H2S decomposition in the subsurface (e.g., oil and gas reservoirs) and wellbores, but first they need to be upscaled as bulk, robust, and recyclable materials. This review presents a guide for the development of the upstream energy production technology via photocatalytic H2S conversion

Tracking Charge Transfer to Residual Metal Clusters in Conjugated Polymers for Photocatalytic Hydrogen Evolution

Semiconducting polymers are versatile materials for solar energy conversion and have gained popularity as photocatalysts for sunlight-driven hydrogen production. Organic polymers often contain residual metal impurities such as palladium (Pd) clusters that are formed during the polymerization reaction, and there is increasing evidence for a catalytic role of such metal clusters in polymer photocatalysts. Using transient optical spectroscopies on nanoparticles of F8BT, P3HT, and the dibenzo[b,d]thiophene sulfone homopolymer, P10, we demonstrate how differences in the timescale of electron transfer to Pd clusters translate into hydrogen evolution activity optima at extremely different residual Pd concentrations. For F8BT nanoparticles with common Pd concentrations of >1000 ppm (>0.1 wt. %), we find that residual Pd clusters quench photogenerated excitons via energy and electron transfer on the fs – ns timescale, thus outcompeting reductive quenching via the electron donor diethylamine in the solution phase. We spectroscopically identify reduced Pd clusters in our F8BT nanoparticles from the µs timescale onwards and show that the predominant location of long-lived electrons gradually shifts to the F8BT polymer when the Pd content is lowered. However, a low yield of long-lived electrons limits the hydrogen evolution activity of F8BT. P10, on the other hand, exhibits a substantially higher hydrogen evolution activity, which we demonstrate results from higher yields of long-lived electrons compared to F8BT due to more efficient reductive quenching. Surprisingly, and despite the higher performance of P10, long-lived electrons reside on the P10 polymer rather than on the Pd clusters in P10 particles, even at very high Pd concentrations of 27,000 ppm (2.7 wt. %). We show that these long-lived electrons in P10 react orders of magnitude slower at lower Pd levels, which suggests that their transfer to Pd sites constitutes a kinetic bottleneck and thus reveals a direction towards further improvements for this already very performant material. In contrast, long-lived electrons in F8BT already reside on Pd clusters before the typical timescale of hydrogen evolution. This comparison illustrates that P10 exhibits efficient reductive quenching but slow electron transfer to residual Pd clusters, whereas the opposite is the case for F8BT. We discuss possible reasons for this pronounced difference in the predominant location of long-lived electrons in F8BT and P10. Our results suggest that the development of even more efficient polymer photocatalysts should target materials that combine both rapid reductive quenching and rapid charge transfer to a metal-based co-catalyst

Enhanced photocatalytic hydrogen evolution from organic semiconductor heterojunction nanoparticles

Photocatalysts formed from a single organic semiconductor typically suffer from inefficient intrinsic charge generation, which leads to low photocatalytic activities. We demonstrate that incorporating a heterojunction between a donor polymer (PTB7-Th) and non-fullerene acceptor (EH-IDTBR) in organic nanoparticles (NPs) can result in hydrogen evolution photocatalysts with greatly enhanced photocatalytic activity. Control of the nanomorphology of these NPs was achieved by varying the stabilizing surfactant employed during NP fabrication, converting it from a core–shell structure to an intermixed donor/acceptor blend and increasing H2 evolution by an order of magnitude. The resulting photocatalysts display an unprecedentedly high H2 evolution rate of over 60,000 µmol h−1 g−1 under 350 to 800 nm illumination, and external quantum efficiencies over 6% in the region of maximum solar photon flux