Polymeric Coatings for Targeted Nanoparticle Delivery to Subsurface Contaminants

Terrestrial oil spills account for the majority of oil spills world wide and present a challenging remediation problem owing to the inaccessibility of subsurface petroleum hydrocarbons (PHC). Contaminants such as crude oil demonstrate acute and chronic toxicity, necessitating remediation activity which is applied in the form of ex situ and in situ treatments. Among in situ remediation techniques, nanomaterial-based treatment strategies have been developed over the past decade to take advantage of improved subsurface mobility and reaction kinetics due to particle size. Increased use of nanoremediation has led to development of coating strategies to improve efficiency of use, and such techniques have raised concerns over the release of mobile nanoparticles into the wider environment. This thesis focuses on the development of a nanoparticle coating to facilitate nanoparticle (NP) aqueous stability, mobility in porous media, and preferential adsorption to target contaminants in porous media. The concept of targeted delivery is borrowed from nano-medicine, where chemotherapeutic drugs are encapsulated by nanomaterials which target accumulation in diseased material through active or passive means. In this thesis, an amphiphilic polymer coating allows NP binding to a hydrophobic interface to localize the NP at the site of contamination and reduce NP migration past contaminated zones. The targeted binding, realized through hydrophobic interactions between the nanoparticle coating and the crude oil model contaminant, is an example of an active targeting technique. The NP surface was modified by oleic acid and Pluronic deposited in layers to produce an externally amphiphilic coating capable of stabilizing the NP in water and interacting with crude oil. By modifying the Pluronic coating concentration and Pluronic molecule hydrophobicity, we were able to tune the recovery of NP transport through clean porous media and NP binding to oil-impacted porous media. It was also found that Pluronic coating concentration influenced the morphology of the NP, producing larger aggregates of nanoparticles or individually stabilized nanoparticles. The effect of environmental factors such as oil concentration in porous media, oil type, temperature, and pH on nanoparticle transport and binding in flow-through sand packed columns was investigated. It was found that higher oil concentrations, longer crude oil molecules, and higher temperatures resulted in higher NP binding. pH was found to have no effect on nanoparticle attachment to clean or oil-impacted sands within the pH range of 5 – 9. High temperature was used to demonstrate complete NP retention in oil-impacted natural aquifer sand packed columns flow-through experiments, and solute transport simulation software was used to model NP transport and binding using an advection-dispersion equation with single-site attachment limited by Langmuirian blocking (1D-USAT). These parameters were used to predict the NP attachment profile within sand packed columns and how it might change under different conditions such as higher flow rate or oil concentration. NP attachment to clean sand was found to be in the range of 2 – 13 mg/kg and attachment was found to increase in the presence of oily sand in the range of 8 – 32 mg/kg, depending on the nanoparticle formulation and environmental factors selected. The attachment rate (kattach) for nanoparticles in oil-impacted sand exceeded the kattach for nanoparticles in clean sand by approximately one order of magnitude (10x). The attachment rates varied on the order of 10-5 - 10-4 s-1 in clean sand, while attachment rates varied on the order of 10-4 - 10-3 s-1 in oily sand. Detachment rates (kdetach) in clean sand flow-through were determined to be approximately equal based on 1D-USAT modelling of experimental data – approximately 10-6 s-1. The NP coating strategy was applied to multiple NP core materials, including iron oxide, silver, and cobalt ferrite, all produced using different synthetic methods. The coated nanoparticles all demonstrated preferential binding to crude oil-impacted sands in binding batch tests, as well as breakthrough in clean sand transport experiments and retention in oil-impacted sand transport experiments. This showed that the NP coating could be applied to various types of NPs and conferred targeted delivery behaviour on each. Finally, potential application of targeted NP delivery to oil-impacted porous media was explored through the investigation of X-Ray computed tomography (X-Ray CT) as a sensing technique for detecting NP bound to oil-impacted sand. The oil-impacted sand exposed to Pluronic-coated NPs generated a CT signal sufficient to differentiate it from oil-impacted sand which was not exposed to NP. Conversely, clean sand exposed to Pluronic-coated NPs did not generate a substantial CT signal. This indicates that targeted NP binding to oil-impacted porous media may have use as a contrast enhancer for detecting contaminated zones at sites of concern. This thesis summarizes the development process of a nanoparticle coating facilitating transport through porous media and targeted binding to crude oil emplaced therein. The Pluronic-coated nanoparticles demonstrated preferential attachment to oil-impacted sediments, transport through clean sand packed columns, and retention in oil-impacted sand packed columns. This nanoparticle coating-strategy shows promise as a versatile technique for enhancing nanoparticle accumulation in contaminated subsurface areas which may enable contaminant detection and enhanced remediation, as well as reduce uncertain nanoparticle environmental fate in future applications

Comproportionation of CO2 and Cellulose to Formate Using a Floating Semiconductor-Enzyme Photoreforming Catalyst

Funding Information: We would like to thank the European Research Council (ERC) for a Proof of Concept Grant (SolReGen; to E.L. and E.R.) and a Consolidator Grant (MatEnSAP; to M.M. and E.R.), the Swiss National Science Foundation (Early Postdoc Fellowship: P2EZP2 191791 to E.L.) as well as the National Science and Engineering Research Council of Canada (NSERC) for a Postdoctoral Fellowship (S.L.). We thank also Fundação para a Ciência e Tecnologia (Portugal) for fellowship DFA/BD/7897/2020 (R.M.), grant PTDC/BII-BBF/2050/2020 (I.A.C.P.), MOSTMICRO-ITQB unit (UIDB/04612/2020 and UIDP/04612/2020) and Associated Laboratory LS4FUTURE (LA/P/0087/2020). Ariffin Mohamad Annuar, Subhajit Bhattacharjee, Dongseok Kim (University of Cambridge) and Victor Mougel (ETH Zürich) are acknowledged for helpful discussions. Funding Information: We would like to thank the European Research Council (ERC) for a Proof of Concept Grant (SolReGen; to E.L. and E.R.) and a Consolidator Grant (MatEnSAP; to M.M. and E.R.), the Swiss National Science Foundation (Early Postdoc Fellowship: P2EZP2 191791 to E.L.) as well as the National Science and Engineering Research Council of Canada (NSERC) for a Postdoctoral Fellowship (S.L.). We thank also Fundação para a Ciência e Tecnologia (Portugal) for fellowship DFA/BD/7897/2020 (R.M.), grant PTDC/BII‐BBF/2050/2020 (I.A.C.P.), MOSTMICRO‐ITQB unit (UIDB/04612/2020 and UIDP/04612/2020) and Associated Laboratory LS4FUTURE (LA/P/0087/2020). Ariffin Mohamad Annuar, Subhajit Bhattacharjee, Dongseok Kim (University of Cambridge) and Victor Mougel (ETH Zürich) are acknowledged for helpful discussions. Publisher Copyright: © 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.Formate production via both CO2 reduction and cellulose oxidation in a solar-driven process is achieved by a semi-artificial biohybrid photocatalyst consisting of immobilized formate dehydrogenase on titanium dioxide (TiO2|FDH) producing up to 1.16±0.04 mmolformate g (Formula presented.) −1 in 24 hours at 30 °C and 101 kPa under anaerobic conditions. Isotopic labeling experiments with 13C-labeled 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 per m2 irradiation area after 24 hours. This work demonstrates the synergistic solar-driven valorization of solid and gaseous waste streams using a biohybrid photoreforming catalyst in aqueous solution and will thus provide inspiration for the development of future semi-artificial waste-to-chemical conversion strategies.publishersversionpublishe

Scavenging amphipods from the Wallaby-Zenith Fracture Zone : Extending the hadal paradigm beyond subduction trenches

Acknowledgements We would like to thank Nick Cuomo for assis- tance with lander deployments, Prof Darren Evans and Dr James Kitson (Newcastle University, UK) for bench space in the Molecular Diagno- sis Facility, Ed Hendrycks (Canadian Museum of Nature, Canada) for guidance on the Cleonardo sp. identification, and Dr Shannon Flynn (Newcastle University, UK) for constructive comments on manuscript drafts. We extend thanks to the Captain and crew on the 2017 R/V SONNE Expedition SO258 Leg 1, especially joint Chief Scientists Dr Reinhard Werner (GEOMAR, Germany) and Prof Hans-Joachim Wagner (University of Tübingen, Germany) and Oleg Lechenko and Julia Marinova (P.P. Shirshov Institute of Oceanology of the Russian Academy of Sciences, Russia) for the acquisition and processing of the bathymetric data. We are appreciative of the reviewers for their constructive comments and suggestions that improved the manuscript. Funding Participation on the R/V SONNE Expedition SO258 was sup- ported by Newcastle University’s Research Infrastructure Fund (RiF), Exploration of Extreme Ocean Environments, awarded to AJJ. The genetic analysis was funded by Newcastle University through internal funds to JNJW and the University of Aberdeen by the Natural Environment Research Council (NERC), UK Grant NE/N01149X/1, awarded to SBP.Peer reviewedPublisher PD

Targeted nanoparticle binding & detection in petroleum hydrocarbon impacted porous media

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.chemosphere.2018.10.046 © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/Targeted nanoparticle binding has become a core feature of experimental pharmaceutical product design which enables more efficient payload delivery and enhances medical imaging by accumulating nanoparticles in specific tissues. Environmental remediation and geophysical monitoring encounter similar challenges which may be addressed in part by the adoption of targeted nanoparticle binding strategies. This study illustrates that engineered nanoparticles can bind to crude oil-impacted silica sand, a selective adsorption driven by active targeting based on an amphiphilic polymer coating. This coating strategy resulted in 2 mg/kg attachment to clean silica sand compared to 8 mg/kg attachment to oil-impacted silica sand. It was also shown that modifying the surface coating influenced the binding behaviour of the engineered nanoparticles – more hydrophobic polymers resulted in increased binding. Successful targeting of Pluronic-coated iron oxide nanoparticles to a crude oil and silica sand mixture was demonstrated through a combined quantitative Orbital Emission Spectroscopy mass analysis supported by Vibrating Scanning Magnetometer magnetometry, and a qualitative X-ray micro-computed tomography (CT) visualization approach. These non-destructive characterization techniques facilitated efficient analysis of nanoparticles in porous medium samples with minimal sample preparation, and in the case of X-Ray CT, illustrated how targeted nanoparticle binding may be used to produce 3-D images of contaminated porous media. This work demonstrated successful implementation of nanoparticle targeted binding toward viscous LNAPL such as crude oil in the presence of a porous medium, a step which opens the door to successful application of targeted delivery technology in environmental remediation and monitoring.Natural Sciences and Engineering Research Council of Canad

Acoustic trauma slows AMPAR-mediated EPSCs in the auditory brainstem, reducing GluA4 subunit expression as a mechanism to rescue binaural function

Damaging levels of sound (acoustic trauma, AT) diminish peripheral synapses, but what is the impact on the central auditory pathway? Developmental maturation of synaptic function and hearing were characterized in the mouse lateral superior olive (LSO) from postnatal day 7 (P7) to P96 using voltage-clamp and auditory brainstem responses. IPSCs and EPSCs show rapid acceleration during development, so that decay kinetics converge to similar sub-millisecond time-constants (τ, 0.87 ± 0.11 and 0.77 ± 0.08 ms, respectively) in adult mice. This correlated with LSO mRNA levels for glycinergic and glutamatergic ionotropic receptor subunits, confirming a switch from Glyα2 to Glyα1 for IPSCs and increased expression of GluA3 and GluA4 subunits for EPSCs. The NMDA receptor (NMDAR)-EPSC decay τ accelerated from >40 ms in prehearing animals to 2.6 ± 0.4 ms in adults, as GluN2C expression increased. In vivo induction of AT at around P20 disrupted IPSC and EPSC integration in the LSO, so that 1 week later the AMPA receptor (AMPAR)-EPSC decay was slowed and mRNA for GluA1 increased while GluA4 decreased. In contrast, GlyR IPSC and NMDAR-EPSC decay times were unchanged. Computational modelling confirmed that matched IPSC and EPSC kinetics are required to generate mature interaural level difference functions, and that longer-lasting EPSCs compensate to maintain binaural function with raised auditory thresholds after AT. We conclude that LSO excitatory and inhibitory synaptic drive matures to identical time-courses, that AT changes synaptic AMPARs by expression of subunits with slow kinetics (which recover over 2 months) and that loud sounds reversibly modify excitatory synapses in the brain, changing synaptic function for several weeks after exposure

Floating Carbon Nitride Composites for Practical Solar Reforming of Pre-Treated Wastes to Hydrogen Gas.

Funder: Hermann und Marianne Straniak StiftungFunder: Natural Sciences and Engineering Research Council of CanadaSolar reforming (SR) is a promising green-energy technology that can use sunlight to mitigate biomass and plastic waste while producing hydrogen gas at ambient pressure and temperature. However, practical challenges, including photocatalyst lifetime, recyclability, and low production rates in turbid waste suspensions, limit SR's industrial potential. By immobilizing SR catalyst materials (carbon nitride/platinum; CNx |Pt and carbon nitride/nickel phosphide; CNx |Ni2 P) on hollow glass microspheres (HGM), which act as floating supports enabling practical composite recycling, such limitations can be overcome. Substrates derived from plastic and biomass, including poly(ethylene terephthalate) (PET) and cellulose, are reformed by floating SR composites, which are reused for up to ten consecutive cycles under realistic, vertical simulated solar irradiation (AM1.5G), reaching activities of 1333 ± 240 µmolH2 m-2 h-1 on pre-treated PET. Floating SR composites are also advantageous in realistic waste where turbidity prevents light absorption by non-floating catalyst powders, achieving 338.1 ± 1.1 µmolH2 m-2 h-1 using floating CNx versus non-detectable H2 production with non-floating CNx and a pre-treated PET bottle as substrate. Low Pt loadings (0.033 ± 0.0013% m/m) demonstrate consistent performance and recyclability, allowing efficient use of precious metals for SR hydrogen production from waste substrates at large areal scale (217 cm2 ), taking an important step toward practical SR implementation

Floating Carbon Nitride Composites for Practical Solar Reforming of Pre-treated Wastes to Hydrogen Gas

Photoreforming (PR) is a promising green-energy technology that can use sunlight to mitigate biomass and plastic waste while producing hydrogen gas at ambient pressure and temperature. However, practical challenges including photocatalyst lifetime, recyclability, and low production rates in turbid waste suspensions limit PR’s industrial potential. By immobilising PR catalyst materials (carbon nitride/platinum; CNx|Pt and carbon nitride/nickel phosphide; CNx|Ni2P) on hollow glass microspheres, which act as floating supports enabling practical composite recycling, such limitations can be overcome. Substrates derived from plastic and biomass, including poly(ethylene terephthalate) (PET) and cellulose, are reformed by floating PR composites, which are reused for up to 10 consecutive cycles under realistic, vertical simulated solar irradiation (AM1.5G), reaching activities of 921 ± 166 µmolH2 m−2 h−1 on pre-treated PET. Floating PR composites are also advantageous in realistic waste where turbidity prevents light absorption by non-floating catalyst powders, achieving 503.2 ± 1.9 µmolH2 m−2 h−1 using floating CNx versus non-detectable H2 production with non-floating CNx. Low Pt loadings (0.033 ± 0.0013 % m/m) demonstrate consistent performance and recyclability, allowing efficient use of precious metals for PR hydrogen production at the largest areal scale (217 cm2) reported to date, taking an important step toward practical PR implementation

Solar reforming as an emerging technology for circular chemical industries.

The adverse environmental impacts of greenhouse gas emissions and persistent waste accumulation are driving the demand for sustainable approaches to clean-energy production and waste recycling. By coupling the thermodynamically favourable oxidation of waste-derived organic carbon streams with fuel-forming reduction reactions suitable for producing clean hydrogen or converting CO2 to fuels, solar reforming simultaneously valorizes waste and generates useful chemical products. With appropriate light harvesting, catalyst design, device configurations and waste pre-treatment strategies, a range of sustainable fuels and value-added chemicals can already be selectively produced from diverse waste feedstocks, including biomass and plastics, demonstrating the potential of solar-powered upcycling plants. This Review highlights solar reforming as an emerging technology that is currently transitioning from fundamental research towards practical application. We investigate the chemistry and compatibility of waste pre-treatment, introduce process classifications, explore the mechanisms of different solar reforming technologies, and suggest appropriate concepts, metrics and pathways for various deployment scenarios in a net-zero-carbon future

Mesoporous Hollow Sphere Titanium Dioxide Photocatalysts through Hydrothermal Silica Etching

Robust, monodisperse, mesoporous titanium dioxide (TiO₂) submicrometer hollow spheres were synthesized through a single step hydrothermal silica etching reaction under mild conditions. Efficient silica (SiO₂) removal was achieved without the use of toxic reagents, and a unique controllable silica redeposition mechanism was identified, imparting the hollow spheres with excellent structural integrity. The parameters of the hydrothermal reaction affecting the etching process, including pH, temperature, and silica concentration, were systematically investigated and optimized for the production of silica-templated hollow structures. The resulting processing conditions yielded TiO₂ hollow spheres with a surface area of ∼300 m² g^–1 and anatase phase crystallization, which exhibited high adsorption capacity for methylene blue dye and good photocatalytic activity without requiring high-temperature calcination

Comproportionation of CO2 and Cellulose to Formate Using a Floating Semiconductor-Enzyme Photoreforming Catalyst.

Funder: National Science and Engineering Research Council of CanadaFunder: Swiss National Science Foundation; Id: http://dx.doi.org/10.13039/501100001711; Grant(s): Early Postdoc Fellowship: P2EZP2_191791Formate production via both CO2 reduction and cellulose oxidation in a solar-driven process is achieved by a semi-artificial biohybrid photocatalyst consisting of immobilized formate dehydrogenase on titanium dioxide (TiO2 |FDH) producing up to 1.16±0.04 mmolformate  g TiO 2 ${{_{\ {\rm TiO}{_{2}}}}}$ -1 in 24 hours at 30 °C and 101 kPa under anaerobic conditions. Isotopic labeling experiments with 13 C-labeled 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 per m2 irradiation area after 24 hours. This work demonstrates the synergistic solar-driven valorization of solid and gaseous waste streams using a biohybrid photoreforming catalyst in aqueous solution and will thus provide inspiration for the development of future semi-artificial waste-to-chemical conversion strategies