Exploring the Full Potential of Photocatalytic Carbon Dioxide Reduction Using a Dinuclear Re2Cl2 Complex Assisted by Various Photosensitizers

Photosensitizing units have already been applied to enable light-driven catalytic reduction of CO2 with mononuclear rhenium complexes. However, dinuclear catalytic systems that are able to activate CO2 in a cooperative bimetallic fashion have only rarely been combined with photosensitizers. We here present detailed studies on the influence of additional photosensitizers on the catalytic performance of a dirhenium complex (Re2Cl2) and present correlations with spectroscopic measurements, which shed light on the reaction mechanism. The use of [Ir(dFppy)3] (Ir, dFppy=2-(4,6-difluorophenyl)pyridine)) resulted in considerably faster CO2 to CO transformation than [Cu(xant)(bcp)]PF6 (Cu, xant=xantphos, bcp=bathocuproine). Emission quenching studies, transient absorption as well as IR spectroscopy provide information about the electron transfer paths of the intermolecular systems. It turned out that formation of double reduced species [Re2Cl2]2− along with an intermediate with a Re−Re bond ([ReRe]) can be taken as an indication of multi-electron storage capacity. Furthermore, under catalytic conditions a CO2-bridged intermediate was identified.German Research FoundationDFG http://dx.doi.org/10.13039/501100001659Peer Reviewe

Outcome and treatment-related adverse events of combined immune checkpoint inhibition with flipped dosing in a real-world cohort of 79 patients with metastasized melanoma

IntroductionCombined immune checkpoint inhibition (ICI) with ipilimumab and nivolumab is a widely used treatment regimen for metastatic melanoma with non-resectable metastases. Nevertheless, the standard dose of ipilimumab 3 mg/kg bw and nivolumab 1 mg/kg bw is associated with a high rate of treatment-related adverse events (trAEs) (59% grade 3–4). In the CheckMate 511 study, it could be shown that flipped dosing with ipilimumab 1 mg/kg bw and nivolumab 3 mg/kg bw resulted in a significant reduction of trAE.MethodsWe have also used this regimen in the clinical setting and report the trAE, progression-free survival, and overall survival for 79 patients with metastatic melanoma who started combined ICI in the flipped dosing between March 2019 and April 2020.Resultsin total, 40 patients started first-line, 50% of whom had an elevated lactate dehydrogenase level at baseline. The disease control rate of these patients was 50%. The 2-year overall survival rate 67%. Moreover, 33% of the patients suffered grade 3 or 4 treatment related adverse events. DiscussionThe results of our study correspond very well to the results of the CheckMate 511 study (2-year OS: 65%, grade 3-4 immune-related side effects: 35%). Combined ICI with ipilimumab 1 mg/kg bw and nivolumab 3 mg/kg bw seems to be an equally effective but better-tolerated therapy regimen for metastasized melanoma patients, also in a real-world cohort

Successful treatment of metastatic uveal melanoma with ipilimumab and nivolumab after severe progression under tebentafusp: a case report

Metastatic uveal melanoma (UM) is a rare form of melanoma differing from cutaneous melanoma by etiology, prognosis, driver mutations, pattern of metastases and poor response rate to immune checkpoint inhibitors (ICI). Recently, a bispecific gp100 peptide-HLA-directed CD3 T cell engager, tebentafusp, has been approved for the treatment of HLA-A*02:01 metastatic or unresectable UM. While the treatment regime is complex with weekly administrations and close monitoring, the response rate is limited. Only a few data exist on combined ICI in UM after previous progression on tebentafusp. In this case report, we present a patient with metastatic UM who first suffered extensive progression under treatment with tebentafusp but in the following had an excellent response to combined ICI. We discuss possible interactions that could explain responsiveness to ICI after pretreatment with tebentafusp in advanced UM

Electric Potential Distribution Inside the Electrolyte During High Voltage Electrolysis

Applying an external potential difference between two electrodes leads to a voltage drop in an ion conducting electrolyte. This drop is particularly large in poorly conducting electrolytes and for high currents. Measuring the electrolyte potential is relevant in electrochemistry, e.g., bipolar electrochemistry, ohmic microscopy, or contact glow discharge electrolysis. Here we study the course of the electrolyte potential during high voltage electrolysis in an electrolysis cell using two reversible hydrogen electrodes as reference electrodes, placed at different positions in the electrolyte. The electrolysis is performed with a Pt working and stainless steel counter electrode in a KOH solution. A computational COMSOL® model is devised which supports the experimentally obtained potential distribution. The influence of the cell geometry on the electrolyte potentials is evaluated. Applying the knowledge of the potential distribution to the formation of a Au oxide surface structure produced during high voltage electrolysis, we find that the amount of oxide formed is related to the current rather than the applied voltage

Using auxiliary electrochemical working electrodes as probe during contact glow discharge electrolysis: A proof of concept study

Plasma in-liquid by means of anodic contact glow discharge electrolysis (aCGDE) is a grow- ing research field allowing the selective modifi- cation of the electrode and the electrolyte. The aim of this proof of concept study is to demon- strate that auxiliary electrochemical electrodes placed in vicinity to the plasma electrode, can be modified by aCGDE. Furthermore, we illus- trate in how far such auxiliary electrodes can be used as a probe to detect products (in particu- lar H2 , H2O2 , and O2 ) formed in the solution by aCGDE via electrochemical techniques. In this work aCGDE is achieved by applying a voltage of 580 V to a small Pt wire (plasma electrode) vs. a large stainless steel counter electrode. An auxiliary Pt electrochemical working electrode, operated in a three electrode configuration, is placed at different distances from the plasma working electrode. Depending on the distance, we find small changes in the electrode struc- ture. More importantly, we will show that in principle the local H2 O2 concentration in the electrolyte can be monitored operando. After aCGDE the concentration changes with time and depends on the distance from the plasma electrode

Biomarkers Associated with Immune-Related Adverse Events under Checkpoint Inhibitors in Metastatic Melanoma

Immune checkpoint inhibitors (ICI) have revolutionized the therapeutic landscape of metastatic melanoma. However, ICI are often associated with immune-related adverse events (IRAE) such as colitis, hepatitis, pancreatitis, hypophysitis, pneumonitis, thyroiditis, exanthema, nephritis, myositis, encephalitis, or myocarditis. Biomarkers associated with the occurrence of IRAE would be desirable. In the literature, there is only little data available and furthermore mostly speculative, especially in view of genetic alterations. Our major aim was to check for possible associations between NGS-based genetic alterations and IRAE. We therefore analyzed 95 melanoma patients with ICI and evaluated their NGS results. We checked the data in view of potential associations between copy number variations (CNVs), small variations (VARs), human leucocyte antigen (HLA), sex, blood count parameters, pre-existing autoimmune diseases and the occurrence of IRAE. We conducted a literature research on genetic alterations hypothesized to be associated with the occurrence of IRAE. In total, we identified 39 genes that have been discussed as hypothetical biomarkers. We compared the list of these 39 genes with the tumor panel that our patients had received and focused our study on those 16 genes that were also included in the tumor panel used for NGS. Therefore, we focused our analyses on the following genes: AIRE, TERT, SH2B3, LRRK2, IKZF1, SMAD3, JAK2, PRDM1, CTLA4, TSHR, FAN1, SLCO1B1, PDCD1, IL1RN, CD274, UNG. We obtained relevant results: female sex was significantly associated with the development of hepatitis, combined immunotherapy with colitis, increased total and relative monocytes at therapy initiation were significantly associated with the development of pancreatitis, the same, pre-existing autoimmune diseases. Further significant associations were as follows: HLA homozygosity (hepatitis), and VARs on SMAD3 (pancreatitis). Regarding CNVs, significant markers included PRDM1 deletions and IL1RN (IRAE), CD274 duplications and SLCO1B1 (hepatitis), PRDM1 and CD274 (encephalitis), and PRDM1, CD274, TSHR, and FAN1 (myositis). Myositis and encephalitis, both, were associated with alterations of PRDM1 and CD274, which might explain their joined appearance in clinical practice. The association between HLA homozygosity and IRAE was clarified by finding HLA-A homozygosity as determining factor. We identified several genetic alterations hypothesized in the literature to be associated with the development of IRAE and found significant results concerning pre-existing autoimmune diseases and specific blood count parameters. Our findings can help to better understand the development of IRAE in melanoma patients. NGS might be a useful screening tool, however, our findings have yet to be confirmed in larger studies

Nanoporous Au formation on Au substrates via high voltage electrolysis

Nanoporous Au (NPG) films often show distinctly different properties than bare Au electrodes, which make them suitable for various applications in (electro)catalysis or (bio)sensing. A great deal of effort has gone into finding suitable preparation techniques that can be used to target structural properties, such as the pore size or the surface-to-volume ratio. Many of the methods described for preparing these NPG films require complex starting materials such as alloys, multiple synthesis steps, lengthy preparation procedures or a combination of these factors. Here we present an approach that circumvents these difficulties, enabling for a rapid and controlled preparation of NPG films starting from bare Au electrodes. One approach is to prepare in a first step a Au oxide film by high voltage (HV) electrolysis in a KOH solution, which in a second step is reduced either electrochemically or in the presence of H₂O₂. The resulting NPG structures as well as their electrochemically active surface areas strongly depend on the reduction procedure, the concentration and temperature of the H₂O₂-containing KOH solution, as well as the applied voltage and temperature during the HV electrolysis. The NPG film can also be prepared directly by applying electrolysis voltages that result in anodic contact glow discharge electrolysis (aCGDE) over an extended period of time. By carefully adjusting the corresponding parameters, the surface area of the final NPG film can be specifically controlled. The structural properties of the electrodes are investigated by means of XPS, SEM and electrochemical methods

Structural Evolution of Pt, Au, and Cu Anodes by Electrolysis up to Contact Glow Discharge Electrolysis in Alkaline Electrolytes

Applying a voltage to metal electrodes in contact with aqueous electrolytes results in the electrolysis of water at low voltages and plasma formation in the electrolyte at high voltages referred to as contact glow discharge electrolysis (CGDE). While several studies explore parameters that lead to changes in the I-U characteristics in this voltage range, little is known about the evolution of the structural properties of the electrodes. Here we study this aspect on materials essential to electrocatalysis, namely Pt, Au, and Cu. The stationary I-U characteristics are almost identical for all electrodes. Detailed structural characterization by optical microscopy, scanning electron microscopy, and electrochemical approaches reveal that Pt is stable during electrolysis and CGDE, while Au and Cu exhibit a voltage-dependent oxide formation. More importantly, oxides are reduced when the Au and Cu electrodes are kept in the electrolysis solution. We suspect that H2O2 (formed during electrolysis) is responsible for the oxide reduction. The reduced oxides (which are also accessible via electrochemical reduction) form a porous film, representing a possible new class of materials in energy storage and conversion studies.</div