Photocatalytic CO2 Reduction Using Homogeneous Carbon Dots with a Molecular Cobalt Catalyst

A simple and precious-metal free photosystem for the reduction of aqueous CO2 to syngas (CO and H2) is reported consisting of carbon dots (CDs) as the sole light harvester together with a molecular cobalt bis(terpyridine) CO2 reduction co-catalyst. This homogeneous photocatalytic system operates in the presence of a sacrificial electron donor (triethanolamine) in DMSO/H2O solution at ambient temperature. The photocatalytic system exhibits an activity of 7.7 ± 0.2 mmolsyngas gCDs -1 (3.6 ± 0.2 mmolCO gCDs -1 and 4.1 ± 0.1 mmolH2 gCDs -1) after 24 hours of full solar spectrum irradiation (AM 1.5G). Spectroscopic and electrochemical characterization supports that this photocatalytic performance is attributed to a favorable association between CDs and the molecular cobalt catalyst, which results in improved interfacial photoelectron transfer and catalytic mechanism. This work provides a scalable and inexpensive platform for the development of CO2 photoreduction systems using CDs.

Chemoenzymatic Photoreforming: A Sustainable Approach for Solar Fuel Generation from Plastic Feedstocks

Plastic upcycling through catalytic transformations is an attractive concept to valorize waste, but the clean and energy-efficient production of high-value products from plastics remains challenging. Here, we introduce chemoenzymatic photoreforming as a process coupling enzymatic pretreatment and solar-driven reforming of polyester plastics under mild temperatures and pH to produce clean H2 and value-added chemicals. Chemoenzymatic photoreforming demonstrates versatility in upcycling polyester films and nanoplastics to produce H2 at high yields reaching ∼103-104 μmol gsub-1 and activities at >500 μmol gcat-1 h-1. Enzyme-treated plastics were also used as electron donors for photocatalytic CO2-to-syngas conversion with a phosphonated cobalt bis(terpyridine) catalyst immobilized on TiO2 nanoparticles (TiO2|CotpyP). Finally, techno-economic analyses reveal that the chemoenzymatic photoreforming approach has the potential to drastically reduce H2 production costs to levels comparable to market prices of H2 produced from fossil fuels while maintaining low CO2-equivalent emissions.

Swiss CAT+, a Data-driven Infrastructure for Accelerated Catalysts Discovery and Optimization

The Catalysis Hub - Swiss CAT+ is a new infrastructure project funded by ETH-domain, co-headed by EPFL and ETHZ. It offers the scientific community a unique integrated technology platform combining automated and high-throughput experimentation with advanced computational data analysis to accelerate the discoveries in the field of sustainable catalytic technologies. Divided into two hubs of expertise, homogeneous catalysis at EPFL and heterogeneous catalysis at ETHZ, the platform is open to academic and private research groups. Following a multi-year investment plan, both hubs have acquired and developed several high-end robotic platforms devoted to the synthesis, characterization, and testing of large numbers of molecular and solid catalysts. The hardware is associated with a fully digitalized experimental workflow and a specific data management strategy to support closed-loop experimentation and advanced computational data analysis.

Simultaneous Conversion of CO2 and Cellulose to Formate Using a Floating TiO2-Enzyme Photoreforming Catalyst

Formate production via both CO2 reduction and cellulose oxidation in a solar-driven process is achieved by a semiartificial biohybrid photocatalyst consisting of immobilized formate dehydrogenase on titanium dioxide (TiO2|FDH) producing up to 1.16±0.04 mmolformate gTiO2-1 in 24 hours. Isotopic labelling experiments with 13C-labelled substrates support the mechanism of stoichiometric formate formation through both redox half-reactions. TiO2|FDH was further immobilized on hollow glass microspheres to perform more practical floating photoreforming allowing vertical solar light illumination with optimal light exposure of the photocatalyst to real sunlight. Enzymatic cellulose depolymerization coupled to the floating photoreforming catalyst generates 0.36±0.04 mmolformate mirr-2 after 24 h. This work thus presents simultaneous solar-driven valorization of waste streams, demonstrates the advantages of biohybrid photocatalysts in photoreforming for the first time and will provide inspiration for the development of future semi-artificial waste-to-chemical conversion strategies.

A135 ENDOSCOPIC SUBMUCOSAL DISSECTION OF GASTRIC ADENOMAS AND EARLY CARCINOMAS

Background

Management of gastric adenoma and early gastric cancer requires endoscopic resection. This can often be achieved with endoscopic mucosal resection (EMR), which has been shown to be effective with a good safety profile. One disadvantage of EMR is that it is often completed piecemeal, leading to indeterminant margins and higher rates of recurrences that require additional intervention. Endoscopic submucosal dissection (ESD) is a more advanced endoscopic resection technique that has been shown to be more effective than EMR at en-bloc resection. ESD requires high technical proficiency but it is becoming more widely available in western countries.

Purpose

The purpose of this study is to report on the outcomes and rates of complications of gastric ESD completed in a tertiary centre in British Columbia.

Method

All gastric ESD was completed by a senior therapeutic endoscopist who has previously received training in Japan. Retrospective data were collected on all gastric ESD procedures done in St. Paul’s Hospital from May 7th, 2015, when the procedure first became available, to Aug 30th, 2022. Inclusion criteria were all adults who have undergone ESD for resection of a gastric lesion. Exclusion criteria were patients younger than 18. Data collected included demographic variables, polyp characteristics, procedural outcomes, and complications.

Result(s)

A total of 49 ESD procedures were completed. The mean size of the resected lesions was 25.3 mm (range: 5 – 100 mm). Technical success, defined as successful resection of all polypoid tissue, was achieved in 48/49 procedures (98.0%). En bloc resection was achieved in 42/48 (87.5%) completed ESD. The rate of R0 resection was also 42/48 (87.5%). Curative resection, defined as technically successful ESD with an R0 margin and no lymphovascular invasion, was achieved in 41/49 (83.7%) of the cases. In our cohort, 8 patients had adenocarcinoma, 5 of which had a curative resection with no evidence of recurrence. None of the ESD resulted in any intra-procedural or delayed perforation. 5/49 (10.2%) patients had clinically significant post-endoscopic resection bleeding. Out of 37 patients that completed follow-up, 3 (8.1%) had recurrence, and all of them were managed endoscopically. 4/49 (8.2%) of patients required surgery post-ESD.

Conclusion(s)

In our cohort, ESD is an effective endoscopic resection modality for gastric lesions with a high rate of technical success and curative resection. Despite a deeper plane of resection versus other endoscopic resection modalities, its complication rate remains low. Although ESD requires high technical proficiency, its favorable outcomes along with low rates of complication make ESD highly feasible for the resection of gastric lesions. Further research will be needed to study the implementation and outcomes of

ESD in a western setting.

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None

Disclosure of Interest

None Declared

A122 MINIMALLY INVASIVE ENDOSCOPIC RESECTION TECHNIQUES FOR ANORECTAL JUNCTION NEOPLASIA: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background

The management of neoplastic lesions at the anorectal junction remains debated. Endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) have emerged as the primary endoscopic modalities of choice.

Purpose

We sought to compare the performance of ESD and EMR in resection of anorectal neoplasia.

Method

Two authors independently searched MEDLINE, EMBASE and Cochrane Libraries (Jan 2000 – Aug 2021) for citations evaluating the performance of endoscopic resection techniques (ESD, EMR) for lesions involving the anorectal junction (defined as within 20mm of the dentate line). The frequencies and 95% confidence intervals (95% CI) of technical success (complete removal of all neoplastic tissue at index procedure), clinically significant post-endoscopic resection bleeding (CSPEB), delayed perforation, recurrence and referral to surgery were assessed using random-effects modelling.

Result(s)

We included 11 studies (total 563 patients: 414 ESD, 149 EMR) of which nine were ESD and two were EMR studies. Technical success was achieved in 97.2% overall (95% CI 94.8%-98.5%, ESD 97.5% and EMR range 93.9%-98.0%). Clinically significant post-endoscopic resection bleeding occurred in 4.3% (95% CI 1.6%-11.1%, ESD 3.0% and EMR range 8.2%-11.0%). Delayed perforation was not identified. Recurrence at first screening colonoscopy occurred in 4.8% (95% CI 1.9%-11.7%, ESD 3.0% and EMR range 15.4%-18.4%). Referral to surgery for any reason occurred in 5.9% (95% CI 4.3%-8.0%, ESD 6.9%, EMR range 2.0%-3.0%).

Conclusion(s)

ESD and EMR demonstrate high frequencies of technical success but may have different rates of adverse events and recurrence. More studies investigating lesions at the anorectal junction should be conducted including head-to-head analyses between ESD and EMR for low-risk anorectal junction neoplasia.

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None

Disclosure of Interest

None Declared

A120 ENDOSCOPIC CLOSURE TECHNIQUES FOLLOWING ACUTE IATROGENIC PERFORATION -- AN UPDATED SYSTEMATIC REVIEW

Background

Iatrogenic perforation is arguably the most feared adverse event associated with endoscopy. Current American Society for Gastrointestinal Endoscopy (ASGE) and European Society of Gastroenterology Endoscopy (ESGE) guidelines recommend endoscopic closure as the first-line treatment strategy. Historically, this has been achieved using through-the-scope clips (TTSC). Given the emergence of alternative endoscopic closure techniques including over-the-scope clips (OTSC) and endoscopic suturing, we sought to provide an updated review of the literature.

Purpose

To review endoscopic closure techniques following iatrogenic perforation during screening or therapeutic endoscopy.

Method

Based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) Guidelines, an electronic search of MEDLINE and EMBASE from June 1^st, 1946 – Oct 10^th, 2022 was performed. Inclusion criteria was limited to English full-text original citations, with case reports, and cohorts with < 3 patients excluded. Our primary objective was to assess complete defect closure after attempted endoscopic treatment. Outcomes were stratified by modality (TTSC, OTSC, endoscopic suturing) and chronologically based on a previous well received systematic review.

Result(s)

A total of 2549 citations were identified in our electronic search, of which 34 were included representing 830 perforations. Overall, successful endoscopic closure was achieved in 763 cases (91.9%). When stratified by endoscopic closure techniques, range estimates for successful endoscopic closure was 71% – 100%, 57% - 100%, and 100% for TTSC, OTSC and endoscopic suturing respectively. When stratifying chronologically, an improvement in TTSC closure was identified.

Conclusion(s)

Endoscopic defect closure, including TTSC, OTSC and endoscopic suturing, are effective in the management of iatrogenic perforations with increasing TTSC performance over time. It remains the primary treatment strategy for iatrogenic perforation.

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None

Disclosure of Interest

None Declared

A131 ENDOSCOPIC SUBMUCOSAL DISSECTION OF COLORECTAL ADENOMAS AND EARLY ADENOCARCINOMAS: OUTCOMES FROM BRITISH COLUMBIA

Background

Endoscopic resection is the standard of care for the management of colorectal polyps. Larger and more complex polyps require endoscopic mucosal resection (EMR). While complications have been low, EMR is often piecemeal, resulting in indeterminant margins and often a higher recurrence rate. Endoscopic submucosal dissection (ESD) is an advanced endoscopic resection technique with a higher rate of en bloc resection. While more data exist for the resection of gastric lesions with ESD, ESD is becoming more widely used in western countries for the resection of colorectal lesions.

Purpose

The purpose of this study is to report on the outcomes and rates of complications for colorectal ESD completed in a tertiary centre in British Columbia.

Method

All colorectal ESD was completed by a senior therapeutic endoscopist who has previously received training in Japan. Retrospective data were collected on all colorectal ESD procedures done in St. Paul’s Hospital from July 11th, 2016, when the procedure first became available, to Aug 30th, 2022. Inclusion criteria were all adults who have undergone ESD for resection of a colorectal lesion. Exclusion criteria were patients younger than 18. Data collected included demographic variables, polyp characteristics, procedural outcomes, and complications.

Result(s)

A total of 39 ESD procedures were completed. The mean size of the resected lesion was 30.4 mm (range: 5 – 60 mm). Technical success, defined as successful resection of all polypoid tissue, was achieved in 35/39 procedures (89.7%). En-bloc resection was achieved in 27/35 (77.1%) of the completed ESD. The rate of R0 resection was 22/35 (62.9%). Curative resection, defined as technically successful ESD with R0 margin and no lymphovascular invasion, was achieved in 23/39 (59.0%) of the cases and the majority of the patients with non-curative resection that underwent endoscopic surveillance had no recurrence on follow-up. In our cohort, 3/39 (7.7%) patients had adenocarcinoma. None of the ESD resulted in any intra-procedural or delayed perforation. 3/39 (7.7%) patients had clinically significant post-endoscopic resection bleeding. Out of 24 patients that completed follow-up, 4 (16.7%) had recurrence at the resection site that was managed endoscopically. 4/39 (10.3%) of patients required surgery post-ESD.

Conclusion(s)

In our cohort, ESD is an effective endoscopic resection modality for the management of colorectal adenomas and early adenocarcinoma with a high rate of technical success and low rates of complications. Although the rate of curative resection was low, most were the result of R1 or Rx resection and a majority of the follow-ups in this subgroup demonstrated no further recurrence. The rate of en bloc resection is high, especially given the average size of adenomas in this cohort. Although ESD requires high technical proficiency, its favorable outcomes and low complication rates make ESD highly feasible for the resection of colorectal lesions.

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None

Disclosure of Interest

None Declared

Bio-Electrocatalytic Conversion of Food Waste to Ethylene via Succinic Acid as the Central Intermediate

Ethylene is an important feedstock in the chemical industry, but currently requires production from fossil resources. The electrocatalytic oxidative decarboxylation of succinic acid offers in principle an environmentally friendly route to generate ethylene. Here, a detailed investigation of the role of different carbon electrode materials and characteristics revealed that a flat electrode surface and high ordering of the carbon material are conducive for the reaction. A range of electrochemical and spectroscopic approaches such as Koutecky–Levich analysis, rotating ring-disk electrode (RRDE) studies, and Tafel analysis as well as quantum chemical calculations, electron paramagnetic resonance (EPR), and in situ infrared (IR) spectroscopy generated further insights into the mechanism of the overall process. A distinct reaction intermediate was detected, and the decarboxylation onset potential was determined to be 2.2–2.3 V versus the reversible hydrogen electrode (RHE). Following the mechanistic studies and electrode optimization, a two-step bio-electrochemical process was established for ethylene production using succinic acid sourced from food waste. The initial step of this integrated process involves microbial hydrolysis/fermentation of food waste into aqueous solutions containing succinic acid (0.3 M; 3.75 mmol per g bakery waste). The second step is the electro-oxidation of the obtained intermediate succinic acid to ethylene using a flow setup at room temperature, with a productivity of 0.4–1 μmol ethylene cm_electrode^–2 h^–1. This approach provides an alternative strategy to produce ethylene from food waste under ambient conditions using renewable energy.

Correction to "Silica-Supported PdGa Nanoparticles: Metal Synergy for Highly Active and Selective CO2-to-CH3OH Hydrogenation"

[This corrects the article DOI: 10.1021/jacsau.1c00021.].

Self-Assembled Liposomes Enhance Electron Transfer for Efficient Photocatalytic CO2 Reduction

Light-driven conversion of CO₂ to chemicals provides a sustainable alternative to fossil fuels, but homogeneous systems are typically limited by cross reactivity between different redox half reactions and inefficient charge separation. Herein, we present the bioinspired development of amphiphilic photosensitizer and catalyst pairs that self-assemble in lipid membranes to overcome some of these limitations and enable photocatalytic CO₂ reduction in liposomes using precious metal-free catalysts. Using sodium ascorbate as a sacrificial electron source, a membrane-anchored alkylated cobalt porphyrin demonstrates higher catalytic CO production (1456 vs 312 turnovers) and selectivity (77 vs 11%) compared to its water-soluble nonalkylated counterpart. Time-resolved and steady-state spectroscopy revealed that self-assembly facilitates this performance enhancement by enabling a charge-separation state lifetime increase of up to two orders of magnitude in the dye while allowing for a ninefold faster electron transfer to the catalyst. Spectroelectrochemistry and density functional theory calculations of the alkylated Co porphyrin catalyst support a four-electron-charging mechanism that activates the catalyst prior to catalysis, together with key catalytic intermediates. Our molecular liposome system therefore benefits from membrane immobilization and provides a versatile and efficient platform for photocatalysis.

A105 ENDOSCOPIC MUCOSAL RESECTION AND ENDOSCOPIC SUBMUCOSAL DISSECTION FOR ILEOCECAL VALVE NEOPLASIA: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background

Neoplastic lesions at the ileocecal valve (ICV) represent a complex lesion subgroup given the unique anatomical characteristics of this location. Both endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are established techniques for colorectal neoplasia but comparative analyses for ICV lesions are lacking.

Aims

Evaluate the performance of EMR and ESD for ICV neoplasia.

Methods

Between Jan 2000 to Aug 2021, two authors independently searched MEDLINE, EMBASE and Cochrane Libraries for relevant citations evaluating the performance of either EMR and/or ESD for ICV neoplasia; defined as lesions involving at least one component of the ICV complex. The rate of technical success (complete removal of all neoplastic tissue during index procedure of those lesions deemed amenable to endoscopic resection), clinically significant post-endoscopic resection bleeding (CSPEB), delayed perforation, and recurrence were assessed. Meta-analysis was performed using a random-effects model.

Results

Nine studies (367 patients, 252 EMR, 115 ESD) were included in the analysis. Successful removal of all visible neoplastic tissue of those deemed amenable to endoscopic resection was 98.1% (EMR 99.6%, ESD 97.4%). Of note, only 2 studies, both assessing EMR, provided data on lesions which were not considered for endoscopic resection ranging from 5.6–23.7%. Average procedure time ranged from 45–49 minutes for EMR and 52–191 minutes for ESD. Clinically significant post-endoscopic resection bleeding occurred in 6.2% (EMR 9.4%, ESD 4.4%). Delayed perforation occurred in 0.6% (EMR 0.4%, ESD 2.0%). Recurrence occurred in 3.1% (EMR 13.2%, ESD 1.9%).

Conclusions

Endoscopic resection, both with EMR and ESD, demonstrates high technical success and good adverse event profiles amongst ICV neoplasia deemed amenable for endoscopic resection.

Funding Agencies

None

A123 MINIMALLY INVASIVE ENDOSCOPIC RESECTION TECHNIQUE PERFORMANCE FOR PERI-APPENDICEAL COLORECTAL NEOPLASIA: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background

Minimally invasive endoscopic resection techniques, including endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD) and endoscopic full-thickness resection (EFTR) have revolutionized the management of peri-appendiceal colorectal neoplasia. However, questions remain about their comparative performance.

Aims

We sought to evaluate the performance of EMR, ESD and EFTR for peri-appendiceal colorectal neoplasia.

Methods

Two authors independently searched MEDLINE, EMBASE and Cochrane Libraries (Jan 2000 – Aug 2021) for citations evaluating the performance of endoscopic resection techniques (EMR, ESD, EFTR) for peri-appendiceal colorectal neoplasia (defined as those involving or in close proximity to the appendiceal orifice). The incidence rates and 95% confidence intervals (95% CI) of technical success (complete removal of all neoplastic tissue at index procedure), clinically significant post-endoscopic resection bleeding (CSPEB), delayed perforation, recurrence and referral to surgery were assessed using random-effects modelling.

Results

12 studies were included in the analysis (479 patients: 185 EMR, 171 ESD, 123 EFTR). Technical success was achieved in 93.5% (95% CI 90.9%-95.4%, EMR 93.5%, ESD 94.1%, EFTR 92.7%). Clinically significant post-endoscopic resection bleeding occurred in 1.3% (95% CI 0.4%-4.3%, EMR 3.8%, ESD 1.2%, EFTR 0%). Delayed perforation occurred in 1.9% (95% CI 0.9%-3.9%, EMR 0%, ESD 2.4%, EFTR 2.4%). Recurrence occurred in 5.7% (95% CI 2.3%-13.8%, EMR 14.3%, ESD 0.2%, EFTR 12.2–14.3%). Referral to surgery occurred in 9.0% (95% CI 6.7%-12.0%, EMR 8.1%, ESD 9.5%, EFTR 9.8%).

Conclusions

Minimally invasive endoscopic resection techniques including EMR, ESD and EFTR demonstrate high frequencies of technical success with comparable adverse event profiles. They should now be viewed as first-line therapeutic modalities for the management of peri-appendiceal colorectal neoplasia.

Funding Agencies

None

Mechanism-Based Design of Quinoline Potassium Acyltrifluoroborates for Rapid Amide-Forming Ligations at Physiological pH

Potassium acyltrifluoroborates (KATs) undergo chemoselective amide-forming ligations with hydroxylamines. Under aqueous, acidic conditions these ligations can proceed rapidly, with rate constants of ∼20 M^-1 s^-1. The requirement for lower pH to obtain the fastest rates, however, limits their use with certain biomolecules and precludes in vivo applications. By mechanistic investigations into the KAT ligation, including kinetic studies, X-ray crystallography, and DFT calculations, we have identified a key role for a proton in accelerating the ligation. We applied this knowledge to the design and synthesis of 8-quinolyl acyltrifluoroborates, a new class of KATs that ligates with hydroxylamines at pH 7.4 with rate constants >4 M^-1 s^-1. We trace the enhanced rate at physiological pH to unexpectedly high basicity of the 8-quinoline-KATs, which leads to their protonation even under neutral conditions. This proton assists the formation of the key tetrahedral intermediate and activates the leaving groups on the hydroxylamine toward a concerted 1,2-BF₃ shift that leads to the amide product. We demonstrate that the fast ligations at pH 7.4 can be carried out with a protein substrate at micromolar concentrations.

A TiO2 -Co(terpyridine)2 Photocatalyst for the Selective Oxidation of Cellulose to Formate Coupled to the Reduction of CO2 to Syngas

Immobilization of a phosphonated cobalt bis(terpyridine) catalyst on TiO₂ nanoparticles generates a photocatalyst that allows coupling aqueous CO₂ -to-syngas (CO and H₂ ) reduction to selective oxidation of biomass-derived oxygenates or cellulose to formate. An enzymatic saccharification pre-treatment process is employed that enables the use of insoluble cellulose as an electron-donating substrate under benign aqueous conditions suitable for photocatalytic CO₂ conversion. The hybrid photocatalyst consists of solely earth-abundant components, and its heterogeneous nature allows for reuse and operation in aqueous solution for several days at 25 °C, reaching a cellulose-to-formate conversion yield of 17 %. Thus, the proof-of-concept for valorizing two waste streams (CO₂ and biomass) simultaneously into value-added chemicals through solar-driven catalysis is demonstrated.

Silica-Supported PdGa Nanoparticles: Metal Synergy for Highly Active and Selective CO2-to-CH3OH Hydrogenation

The direct conversion of CO₂ to CH₃OH represents an appealing strategy for the mitigation of anthropogenic CO₂ emissions. Here, we report that small, narrowly distributed alloyed PdGa nanoparticles, prepared via surface organometallic chemistry from silica-supported Ga^III isolated sites, selectively catalyze the hydrogenation of CO₂ to CH₃OH. At 230 °C and 25 bar, high activity (22.3 mol_MeOH mol_Pd ^-1 h^-1) and selectivity for CH₃OH/DME (81%) are observed, while the corresponding silica-supported Pd nanoparticles show low activity and selectivity. X-ray absorption spectroscopy (XAS), IR, NMR, and scanning transmission electron microscopy-energy-dispersive X-ray provide evidence for alloying in the as-synthesized material. In situ XAS reveals that there is a dynamic dealloying/realloying process, through Ga redox, while operando diffuse reflectance infrared Fourier transform spectroscopy demonstrates that, while both methoxy and formate species are observed in reaction conditions, the relative concentrations are inversely proportional, as the chemical potential of the gas phase is modulated. High CH₃OH selectivities, across a broad range of conversions, are observed, showing that CO formation is suppressed for this catalyst, in contrast to reported Pd catalysts.

Lewis Acid Strength of Interfacial Metal Sites Drives CH3 OH Selectivity and Formation Rates on Cu-Based CO2 Hydrogenation Catalysts

CH₃ OH formation rates in CO₂ hydrogenation on Cu-based catalysts sensitively depend on the nature of the support and the presence of promoters. In this context, Cu nanoparticles supported on tailored supports (highly dispersed M on SiO₂ ; M=Ti, Zr, Hf, Nb, Ta) were prepared via surface organometallic chemistry, and their catalytic performance was systematically investigated for CO₂ hydrogenation to CH₃ OH. The presence of Lewis acid sites enhances CH₃ OH formation rate, likely originating from stabilization of formate and methoxy surface intermediates at the periphery of Cu nanoparticles, as evidenced by metrics of Lewis acid strength and detection of surface intermediates. The stabilization of surface intermediates depends on the strength of Lewis acid M sites, described by pyridine adsorption enthalpies and ¹³ C chemical shifts of -OCH₃ coordinated to M; these chemical shifts are demonstrated here to be a molecular descriptor for Lewis acid strength and reactivity in CO₂ hydrogenation.

A83 IMPACT OF TELEHEALTH ON MEDICATION ADHERENCE IN GASTROENTEROLOGY CHRONIC DISEASE MANAGEMENT

Background

With the COVID-19 pandemic, the demand and availability of telehealth in outpatient care has increased. Although use of telehealth has been studied and validated for various medical specialties, relatively few studies have looked at its role in gastroenterology despite burden of chronic diseases such as inflammatory bowel disease (IBD).

Aims

To assess effectiveness of telehealth medicine in gastroenterology by comparing medication adherence rate for patients seen with telehealth and traditional in-person appointment for various GI conditions.

Methods

Retrospective chart analysis of patients seen in outpatient gastroenterology clinic was performed to identify patients who were given prescription to fill either through telehealth or in-person appointment. By using provincial pharmacy database, we determined the prescription fill rate.

Results

A total of 241 patients were identified who were provided prescriptions during visit with their gastroenterologists. 128 patients were seen through in-person visit during pre-pandemic period. 113 patients were seen through telehealth appointment during COVID pandemic.

The mean age of patients in telehealth cohort was 42 years (57% male). On average patients had 10 prior visits with their gastroenterologists before index appointment, used for adherence assessment. 92% of patients were seen in follow-up, while 8% were seen in initial consultation. The majority of the patients in the telehealth cohort had IBD (89%), while the remaining 11% had various diagnoses, including functional GI disorder, gastroesophageal reflux disease, viral hepatitis, or hepatobiliary disorders. Biologic therapy was the most commonly prescribed medication (66.4%). 45 patients were provided either new medication or dose change, and 68 patients had prescription refill to continue their current medications. It took a mean of 18 days (SD = 16.2) for patients to fill their prescriptions.

Prescription fill rate for patients seen through telehealth and in-person visit were 98.2% and 89.1% (P = 0.004) respectively. Patients seen through telehealth were 6.8 times more likely to fill their prescriptions compared to the in-person counterparts (OR 6.82, CI 1.51 – 30.68, P = 0.004). When we compared adherence rate while excluding biologic therapies, the prescription fill rate was 94.7% in telehealth group and 81.4% in in-person group (OR 4.11, CI 0.88 – 19.27, P = 0.056). Due to high level of adherence, statistical analysis comparing adherent and non-adherent groups was performed but yielded insignificant results.

Conclusions

Medication adherence rate for patients seen through telehealth was higher compared to patients seen through in-patient visit in this study. Telehealth is a viable alternative for outpatient care especially for patients with chronic GI conditions such as IBD.

Funding Agencies

None

Early surveillance of anthracycline induced cardiotoxicity in children using echocardiography and biomarkers: A prospective study

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): CIHR

Background

Anthracyclines, which are commonly used in cancer treatment can induce myocardial damage, result in heart failure during treatment and have cardiac effects even decades after treatment. Monitoring of cardiotoxicity during treatment is largely based on the use of echocardiographic functional markers like ejection fraction and more recently myocardial strain imaging. Some studies have also looked at the utility of biomarkers like troponin and BNP. The utility of this surveillance strategy remains controversial as larger prospective studies are lacking.

Purpose

The aim of this study was to prospectively describe the impact of anthracycline treatment on echocardiographic functional parameters and cardiac biomarkers (high sensitivity troponin T and NT-Pro BNP) during the treatment period and twelve months after completion of treatment. In the current study we wanted to look at whether monitoring parameters during treatment were predictive of left ventricular function 12 months after treatment.

Methods

This was a prospective multi-centre nested case-control study of 256 children diagnosed with cancer requiring anthracycline therapy. Baseline functional echocardiographic parameters  and cardiac biomarkers were obtained prior to starting anthracycline therapy, during the treatment protocol, and 12 months after treatment completion. Patients were assigned to one of two comparison groups based on the fractional shortening at the12-month echocardiogram: patients in group 1 had normal fractional shortening, (FS ³ 28%) while patients in group 2 had reduced fractional shortening (FS &lt; 28%).

Results

A total of 917 echoes were performed, 376 of these occurred during the treatment period. FS was reduced in 27 (7%) of echoes obtained during the treatment period with 22 patients developing new onset dysfunction. Twelve months after treatment completion 232 patients had normal FS (Group 1), while 24 patients showed reduced FS (Group 2). Both groups had normal systolic function and cardiac biomarkers at baseline, however patients in group 2 were older at diagnosis (13.2 years (11.8-16) vs 6.5 years (3.4-13.2), p = 0.003) and received a higher cumulative anthracycline dose (200 mg/m2 (143-318) vs 125 mg/m2 (75-200), p= 0.005). One third (8/24) of patients in group 2 had at least 1 abnormal echo during the treatment period compared to 7% (16/232) in the normal group P &lt; 0.001. The proportion of patients with at least one abnormal biomarker during this period however, was similar between groups.

 Conclusion(s)

Patients receiving higher accumulative anthracycline doses and those with abnormal FS during the treatment period are at higher risk of having reduced cardiac function 12 months after treatment. High sensitivity troponin and NT-Pro BNP levels during the treatment period fail to discriminate patients at risk of developing early reduced systolic function. The relationship of these early results to long term cardiac function remains to be demonstrated.

Electronegativity and location of anionic ligands drive yttrium NMR for molecular, surface and solid-state structures

Yttrium is present in various forms in molecular compounds and solid-state structures; it typically provides specific mechanical and optical properties. Hence, yttrium containing compounds are used in a broad range of applications such as catalysis, lasers and optical devices. Obtaining descriptors that can provide access to a detailed structure-property relationship would therefore be a strong base for the rational design of such applications. Towards this goal, ⁸⁹Y (100% abundant spin ½ nucleus), is associated with a broad range of NMR chemical shifts that greatly depend on the coordination environment of Y, rendering ⁸⁹Y NMR an attractive method for the characterization of yttrium containing compounds. However, to date, it has been difficult to obtain a direct relationship between ⁸⁹Y chemical shifts and its coordination environment. Here, we use computational chemistry to model the chemical shift of a broad range of Y(iii) molecular compounds with the goal to reveal the underlying factors that determine the ⁸⁹Y chemical shift. We show through natural chemical shift (NCS)-analysis that isotropic chemical shifts can easily help to distinguish between different types of ligands solely based on the electronegativity of the central atom of the anionic ligands directly bound to Y(iii). NCS-analysis further demonstrates that the second most important parameter is the degree of pyramidalization of the three anionic ligands imposed by additional neutral ligands. While isotropic chemical shifts can be similar due to compensating effects, investigation of the chemical shift anisotropy (CSA) enables discriminating between the coordination environment of Y.

A82 SUCCESSFUL RESECTION OF GRADE 1 DUODENAL NEUROENDOCRINE TUMOURS USING ENDOSCOPIC TECHNIQUES IN TWO CANADIAN HOSPITALS

Background

Given the rarity of duodenal neuroendocrine tumours (dNETs), limited guidelines exist for resection of well-differentiated, ≤10 mm dNETS. As incidence rises, alternatives to surgery are valuable. We present 9 cases of endoscopic dNET resections and a literature review.

Aims

To demonstrate efficacy and safety of endoscopic resection for dNETs ≤10 mm at 2 Canadian hospitals.

Methods

We retrospectively analyzed data on 7 patients that had endoscopic dNET resection from 2013–2018. Endoscopic resection occurred if dNETs were ≤10 mm in diameter, did not extend to the muscularis propria and lymphovascular invasion was absent. WHO 2017 classification was used.

Results

All patients had biopsies and 5 (71%) had EUS prior to resection; 4 females and 3 males underwent resection of 9 dNETs; 2 via cap-assisted snare polypectomy; 4 with cap-assisted band mucosectomy; and 2 over-the-scope clip-assisted resection. The median size was 10 mm (4–11); 6 (67%) dNETS were found in the duodenal bulb, 2 at the D1/D2 junction and 1 in D2 alone. The median age was 68.5 (50–79) years.

All dNETs were submucosal and well-differentiated. The dNETs were resected en bloc, but 3 did not have clear margins. Two procedures were complicated by duodenal perforation; 1 requiring surgery and 18 days in hospital. One case was complicated by bleeding with successful endoscopic hemostasis. The majority (75%) of resections were day procedures.

Patients were followed for 6–12 months with an EGD or chromogrannin A. None of the patients had endoscopic residual disease, but 1 patient required a second procedure to remove a dNET left in situ following the initial resection of 2 dNETs 12 months earlier.

In our literature review of 178 patients, the majority of dNETs were resected by EMR 81% (150/185) versus ESD, similar to our experience. Patients were slightly younger with a mean age of 63.28, and most dNETs (46%) were found in the duodenal bulb. Complications included intraoperative bleeding, perforation and death in 17 (9.55%), 9 (5.06%) and 1 (0.06%) patient(s) respectively. The rate of recurrence was 4/178 (2.25%) and patients had a mean follow up of 26.1 months.

Conclusions

Well-differentiated dNETs ≤10 mm in diameter can be successfully resected endoscopically. Complications can be managed intraoperatively and hospital stay remains minimal.

Funding Agencies

None

A154 ASSESSING COLON SCREENING PROGRAM COLONOSCOPIES IN A NON-HOSPITAL ENDOSCOPY CLINIC

Background

Colorectal cancer is the most commonly diagnosed cancer in British Columbia, affecting 1 in 6 persons. The BC Colon Screening Program (CSP) screens individuals 50–74 years of age with biennial FIT (cut-off 10 mcg/g) with follow-up colonoscopy for positive results. In Vancouver, colonoscopies are performed in a hospital environment; however non-hospital endoscopy clinics have been used in other jurisdictions.

Aims

To investigate the quality of procedure, rate of complications and need to repeat procedures in a hospital setting for colonoscopies performed on CSP patients in a non-hospital setting.

Methods

A retrospective chart review for all CSP colonoscopies performed from 04/19 to 07/19 in a non-hospital endoscopy clinic. Data was collected from an electronic medical record system and included adenoma detection rates; any repeat procedures required in a hospital setting and adverse event rates. Criteria for a repeat in hospital colonoscopy were inadequate bowel preparation, body mass index exceeding the allowable threshold for a non-hospital colonoscopy and identification of a difficult to remove polyp such as a polyp &gt; 20 mm or in a difficult location.

Results

801 FIT positive patients (ages 50–74) underwent colonoscopy in the non-hospital endoscopy clinic. The mean age was 60 years (51% female). The mean time between referral date and procedure date was 192 days. The neoplasia detection rate was 60.2%, there was one (0.1%) adverse event (post-polypectomy bleed) and 21 (2.6%) patients required a repeat colonoscopy in a hospital setting.

Conclusions

Colonoscopy to follow-up a positive FIT in an non-hospital endoscopy clinic was safe and effective with a low number of repeat, in hospital colonoscopies required.

Funding Agencies

None

A80 ADVANCED ENDOSCOPIC RESECTION OF LARGE POLYPS & EARLY NEOPLASIA: OUTCOMES OF ENDOSCOPIC MUCOSAL RESECTION IN BRITISH COLUMBIA

Background

Recent advances have resulted in a new technique termed endoscopic mucosal resection (EMR). This procedure has been successful at removing large or complex polyps and achieving remission rates comparable to surgery. EMR can also be used to remove early, non-metastatic cancer and they are less invasive than surgery. However, they have been associated with their own complications, most serious of which being perforation. This procedure has recently become available in British Columbia for resection of both complex polyps and early established cancers in the colon.

Aims

Here we present patient outcomes of EMR procedures for the resection of colorectal polyps in British Columbia.

Methods

Retrospective data were collected on all EMR procedures done in Vancouver General Hospital and St. Paul’s Hospital (Vancouver, B.C.) from October 2012 (when procedure became available) to July 2019. Inclusion criteria were all adults who had undergone EMR for resection of polyps in the colon. Exclusion criteria were patients younger than 18 or patients who had EMR that resected polyps in the upper GI tract. Patients were referred to one of two endoscopists when one or more polyps suitable for EMR were identified during colonoscopy by other gastroenterologists. Collected data included patient demographics, polyp characteristics, procedure outcome, and complications.

Results

There were 211 EMR procedures performed on 182 patients (48.9% male). Patient age ranged from 27 to 86 (mean = 67.1). A total of 244 colon polyps were removed with an average size of 2.91 cm and ranged from 0.8 cm to 15 cm. Resected polyps had the following distribution: ascending colon (63.5%), transverse colon (10.2%), descending colon (5.7%), sigmoid colon (15.2%), and rectum (5.3%). Of those that reported resection type, 84.2% were piecemeal and 15.8% were en bloc. 40.9% of polyps were tubulovillous adenoma, 33.2% were tubular, 16.2% were sessile serrated, 6.4% were villous, and 3.4% were adenocarcinoma. Patients from 11 of the 211 EMR cases (5.2%) experienced post-procedure bleed and 4 of these 11 patients (36.4%) had been on anti-platelet or anti-coagulants (discontinued before procedure). Overall, patients from 51 (24.2%) EMR cases were on anti-platelet or anti-coagulants. 33 cases (15.6%) had residual polyps at the resection site that required additional endoscopic resection during follow-up and 14 patients (6.6%) required surgery. None of the EMR procedures resulted in perforation.

Conclusions

EMR is an effective minimally-invasive procedures that can be used to remove large, complicated colonic polyps and achieve long-term remission rate. The procedure has an acceptable risk profile, with complication and re-intervention rate similar or less than other procedures used to remove large, complicated polyps.

Funding Agencies

None

A279 EUS-GUIDED BILIARY DRAINAGE IN MALIGNANT DISTAL BILIARY OBSTRUCTION: AN INTERNATIONAL SURVEY TO IDENTIFY BARRIERS OF TECHNOLOGY IMPLEMENTATION

Background

Endoscopic ultrasound-guided biliary drainage (EUS-BD) is a promising alternative to endoscopic retrograde cholangiopancreatography (ERCP) in malignant distal biliary obstruction (MDBO). Recent small randomized controlled trials comparing EUS-BD with ERCP suggest that EUS-BD achieves a similar technical success rate and safety profile while potentially being associated with lower rates of stent dysfunction However, its application in clinical practice has been impeded by various undefined barriers.

Aims

To evaluate the current practice of EUS-BD and the determinants for its clinical implementation in MDBO.

Methods

An online survey was generated using Google Forms. Five endoscopy societies have distributed the survey as of October 10th, 2019. Survey questions measured participant characteristics, EUS-BD in different clinical scenarios, and potential barriers to implementation. Descriptive statistics were calculated using frequencies, chi-square statistics were used for inferential analysis, and a standard step-wise multivariable analysis was performed to identify independent variables for and against the use of EUS-BD.

Results

To date, 102 physicians have participated in the survey (response rate 7.97%). The majority of participants are from North America (39.2%), Asia (31.4%), and Europe (19.6%). Most participants are gastroenterologists with formal therapeutic endoscopy training (66.7%), though only 28.4% have received EUS-BD training. In unresectable cancer, 85.1% of respondents favoured EUS-BD over percutaneous biliary drainage following ERCP failure (p&lt;0.0001), while in borderline resectable disease, 72.3% preferred EUS-BD. On multivariable analysis, male gender, formal training in EUS-BD, and unresectable cancer were independent variables for the use of EUS-BD. Conversely, independent discouraging factors for EUS-BD included fear of adverse events, limited high-quality data, lack of local expertise, and inadequate access to EUS technology.

Conclusions

In this international survey, it appears that EUS-BD is gaining traction, especially in the setting of unresectable disease following ERCP failure. However, barriers to implementation include the lack of high-quality data, fear for adverse events, limited experts in the field, and inadequate access to EUS technology. This suggest the need for high-quality clinical trials, increased endoscopist training in this field, and further technology development in EUS-BD in order to increase its uptake in clinical practice.

Funding Agencies

None

Enhanced CH3OH selectivity in CO2 hydrogenation using Cu-based catalysts generated via SOMC from GaIII single-sites

Small and narrowly distributed nanoparticles of copper alloyed with gallium supported on silica containing residual Ga^III sites can be obtained via surface organometallic chemistry in a two-step process: (i) formation of isolated Ga^III surface sites on SiO₂ and (ii) subsequent grafting of a Cu^I precursor, [Cu(O ^t Bu)]₄, followed by a treatment under H₂ to generate CuGa _x alloys. This material is highly active and selective for CO₂ hydrogenation to CH₃OH. In situ X-ray absorption spectroscopy shows that gallium is oxidized under reaction conditions while copper remains as Cu⁰. This CuGa material only stabilizes methoxy surface species while no formate is detected according to ex situ infrared and solid-state nuclear magnetic resonance spectroscopy.

A89 IMPLEMENTING ENDOSCOPIC SUBMUCOSAL DISSECTION IN A WESTERN CANADIAN SETTING: OUTCOMES, LEARNING CURVE AND LOGISTICAL CONSIDERATIONS

Background

Endoscopic submucosal dissection (ESD) is an advanced resection technique for large gastrointestinal lesions. ESD was developed in Japan and is popular in countries with gastric cancer screening and a high incidence of gastric cancer. ESD has benefits over endoscopic mucosal resection (EMR) such as increased complete resection, en bloc resection and lower recurrence. However, ESD is a longer procedure and is difficult to master in countries with low incidence of early gastric neoplasia which is the ideal anatomic location for learning. There is increasing interest in using ESD techniques including hybrid ESD/EMR in western centers. Barriers include procedure time, perforation risk and challenges accumulating sufficient experience.

Aims

To present our experience implementing an ESD program in British Columbia including outcomes and logistical considerations of interest.

Methods

All ESD procedures since implementation of the program in May 2015 to July 2019 were included. Descriptive statistics and performance indicators over time are reported. All procedures were performed by a staff endoscopist after specialized training. Procedures were performed at two hospitals in British Columbia. Cases were referred from endoscopists and were assessed with dedicated endoscopy with or without endoscopic ultrasound prior to booking ESD.

Results

40 procedures were performed, though only one procedure was performed in the first year (Mean age 70, 67.5% male). ASA class ranged from 1–4 (mean 2.08). 22 lesions were gastric, 13 were rectal, with the remainder throughout the colon. Mean lesion size was 25mm in maximum dimension (interquartile range 15-30mm). 18 procedures were performed under general anesthesia and the remainder using procedural sedation. Total surgical time ranged from 22 to 398 minutes. Mean surgical time was 104 minutes, or 126 minutes including anesthesia. 50% of procedures were performed using hybrid ESD/EMR technique. R0 resection rate across all cases was 68% (60% for hybrid procedures, 80% for strict ESD). En bloc resection rate was 60%. Recurrence rate was 10%. Complication rate was 7.5% all were post-procedure bleeds requiring hospitalization. No perforations occurred. 3 patients required surgery for incomplete resection or invasive cancer on pathology, 3 required repeat endoscopic resection. Surgical time per cm of lesion improved significantly from the first 10 cases to the last 10 (time per cm resected 75 min to 32 min p&lt;0.006).

Conclusions

ESD is an effective therapy for GI neoplasia. ESD is feasible in a Canadian setting. Hybrid techniques tend to be faster though at the expense of R0 resection. Patient centered outcomes in this sample are favorable and comparable to large ESD series. Monitoring of ESD quality is critical for comparison with standard of care as experience with ESD in Canada grows.

Funding Agencies

None

Single-cell reconstruction of follicular remodeling in the human adult ovary

The ovary is perhaps the most dynamic organ in the human body, only rivaled by the uterus. The molecular mechanisms that regulate follicular growth and regression, ensuring ovarian tissue homeostasis, remain elusive. We have performed single-cell RNA-sequencing using human adult ovaries to provide a map of the molecular signature of growing and regressing follicular populations. We have identified different types of granulosa and theca cells and detected local production of components of the complement system by (atretic) theca cells and stromal cells. We also have detected a mixture of adaptive and innate immune cells, as well as several types of endothelial and smooth muscle cells to aid the remodeling process. Our results highlight the relevance of mapping whole adult organs at the single-cell level and reflect ongoing efforts to map the human body. The association between complement system and follicular remodeling may provide key insights in reproductive biology and (in)fertility.

BRD4 bimodal binding at promoters and drug-induced displacement at Pol II pause sites associates with I-BET sensitivity

Background

Deregulated transcription is a major driver of diseases such as cancer. Bromodomain and extra-terminal (BET) proteins (BRD2, BRD3, BRD4 and BRDT) are chromatin readers essential for maintaining proper gene transcription by specifically binding acetylated lysine residues. Targeted displacement of BET proteins from chromatin, using BET inhibitors (I-BETs), is a promising therapy, especially for acute myeloid leukemia (AML), and evaluation of resistance mechanisms is necessary to optimize the clinical efficacy of these drugs.

Results

To uncover mechanisms of intrinsic I-BET resistance, we quantified chromatin binding and displacement for BRD2, BRD3 and BRD4 after dose response treatment with I-BET151, in sensitive and resistant in vitro models of leukemia, and mapped BET proteins/I-BET interactions genome wide using antibody- and compound-affinity capture methods followed by deep sequencing. The genome-wide map of BET proteins sensitivity to I-BET revealed a bimodal pattern of binding flanking transcription start sites (TSSs), in which drug-mediated displacement from chromatin primarily affects BRD4 downstream of the TSS and prolongs the pausing of RNA Pol II. Correlation of BRD4 binding and drug-mediated displacement at RNA Pol II pause sites with gene expression revealed a differential behavior of sensitive and resistant tumor cells to I-BET and identified a BRD4 signature at promoters of sensitive coding and non-coding genes.

Conclusions

We provide evidence that I-BET-induced shift of Pol II pausing at promoters via displacement of BRD4 is a determinant of intrinsic I-BET sensitivity. This finding may guide pharmacological treatment to enhance the clinical utility of such targeted therapies in AML and potentially other BET proteins-driven diseases.

Electronic supplementary material

The online version of this article (10.1186/s13072-019-0286-5) contains supplementary material, which is available to authorized users.

Selective Hydrogenation of CO2 to CH3 OH on Supported Cu Nanoparticles Promoted by Isolated TiIV Surface Sites on SiO2

Small and narrowly distributed Cu nanoparticles, supported on SiO₂ decorated with isolated Ti^IV sites, prepared through surface organometallic chemistry, showed significantly improved CO₂ hydrogenation activity and CH₃ OH selectivity compared to the corresponding Cu nanoparticles supported on SiO₂ . These isolated Lewis acid Ti^IV sites, evidenced by UV/Vis spectroscopy, are proposed to stabilize surface intermediates at the interface between Cu nanoparticles and the support.

C-H Activation and Proton Transfer Initiate Alkene Metathesis Activity of the Tungsten(IV)-Oxo Complex

In alkene metathesis, while group 6 (Mo or W) high-oxidation state alkylidenes are accepted to be key reaction intermediates for both homogeneous and heterogeneous catalysts, it has been proposed that low valent species in their +4 oxidation state can serve as precatalysts. However, the activation mechanism for these latter species-generating alkylidenes-is still an open question. Here, we report the syntheses of tungsten(IV)-oxo bisalkoxide molecular complexes stabilized by pyridine ligands, WO(OR)₂py₃ (R = CMe(CF₃)₂ (2a), R = Si(O tBu)₃ (2b), and R = C(CF₃)₃ (2c); py = pyridine), and show that upon activation with B(C₆F₅)₃ they display alkene metathesis activities comparable to W(VI)-oxo alkylidenes. The initiation mechanism is examined by kinetic, isotope labeling and computational studies. Experimental evidence reveals that the presence of an allylic CH group in the alkene reactant is crucial for initiating alkene metathesis. Deuterium labeling of the allylic C-H group shows a primary kinetic isotope effect on the rate of initiation. DFT calculations support the formation of an allyl hydride intermediate via activation of the allylic C-H bond and show that formation of the metallacyclobutane from the allyl "hydride" involves a proton transfer facilitated by the coordination of a Lewis acid (B(C₆F₅)₃) and assisted by a Lewis base (pyridine). This proton transfer step is rate determining and yields the metathesis active species.

Isolated Zr Surface Sites on Silica Promote Hydrogenation of CO2 to CH3OH in Supported Cu Catalysts

Copper nanoparticles supported on zirconia (Cu/ZrO₂) or related supported oxides (Cu/ZrO₂/SiO₂) show promising activity and selectivity for the hydrogenation of CO₂ to CH₃OH. However, the role of the support remains controversial because most spectroscopic techniques provide information dominated by the bulk, making interpretation and formulation of structure-activity relationships challenging. In order to understand the role of the support and in particular of the Zr surface species at a molecular level, a surface organometallic chemistry approach has been used to tailor a silica support containing isolated Zr(IV) surface sites, on which copper nanoparticles (∼3 nm) are generated. These supported Cu nanoparticles exhibit increased CH₃OH activity and selectivity compared to those supported on SiO₂, reaching catalytic performances comparable to those of the corresponding Cu/ZrO₂. Ex situ and in situ X-ray absorption spectroscopy reveals that the Zr sites on silica remain isolated and in their +4 oxidation state, while ex situ solid-state nuclear magnetic resonance spectroscopy and catalytic performances show that similar mechanisms are involved with the single-site support and ZrO₂. These observations imply that Zr(IV) surface sites at the periphery of Cu particles are responsible for promoting CH₃OH formation on Cu-Zr-based catalysts and provide a guideline to develop selective CH₃OH synthesis catalysts.