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Plants as Nanoparticle Producers

Project: Innovation

Description

Platinum group metals (PGMs) are used in many industrial applications, often as nanoparticles (NPs). PGMs are rare materials, making them highly valuable, but their increasing dispersal in the environment is of growing concern. The metal accumulating ability of plants can be used to capture metals from the environment. Furthermore, our studies demonstrated that plants can produce PGM-NPs which can make high-performing plant-based catalysts, either in their native state or after modification. These high value products could help satisfy demand for precious metals in industry and medicine. However, the full potential of plants as PGM accumulators is yet to be realised and will critically depend on the mechanism for PGM uptake, an area of great controversy.

The aim of this study is to establish whether PGM uptake in plants is via passive diffusion or mediated by (specific) proteins:
-If PGMs cross the membrane via diffusion, associated membrane leakiness ( ‘nanoholes’) is expected to occur. Using Pd (palladium) to represent PGMs, we will test this by exposing excised plant membranes to increasing concentrations of Pd-NPs using patch clamp to record microscopic changes in current. Patch clamp will also be used to record current in the presence and absence of ionic Pd2+.
-If membrane transport is involved, Pd uptake will depend critically on transporter proteins. This will be assessed using a mutant screen of Arabidopsis homozygous T-DNA loss of function mutants representing all ~1200 known and unknown membrane transporters with an emphasis on heavy metal transporters since current research in our lab shows that members from the HMA family are transcriptionally regulated by PGMs. Mutants will be tested for Pd linked traits by exposure to Pd-NPs and ionic Pd2+. Growth and shoot [Pd] will be analysed (using ICP-OES) by comparing those parameters between mutant and wild type plants. Significant (positive or negative) deviations in growth and/or tissue Pd2+ will be confirmed in subsequent in depth experiments.

Key findings

Evidence that a substantial part of PGM uptake occurs via membrane proteins, will greatly enhance our chances to successfully complete a programme to develop plant NP producers. After PoC studies, we will approach UK and EU funders to further develop our product in collaboration with our industrial partners and the University of York ‘Green Chemistry for Excellence’ . Funding will be sought from Industrial CASE (BBSRC), IB Catalyst (BBSRC) schemes, any of the academia-industry Collaborative research (IPA, LINK) initiatives and Horizon 2020 ERC Proof of Concept Funds.

Follow on research will develop plants with enhanced removal of PGMs from the environment and NP formation. Species will be evaluated for their efficacy and suitability in differing environments (e.g. soil type, PGM level) whereas catalytic properties of NP-containing plant biomass will be evaluated and improved.
Impact: Plant trials will be conducted and seeds distributed to potential users (e.g. Highway agency, environmental remediation industries, metal industries, mining industries) and applied to industrial effluents high in PGMs and on road verges where PGM deposit from catalytic converters is prevalent. Bulk plant material will be collected which can be directly commercialised as catalytic material and/or used for NP extraction.

Commercialisation: Current market value of Pd-NP is ~£15k per kg. Product commercialisation will be achieved in concert with our industrial partner; TeeGene Biotech’s core business is the development of biobased products. TeeGene will be involved in developing NP purification processes and NP modifications that will optimise NP stability and functionality for specific catalytic applications.
StatusFinished
Effective start/end date1/12/1531/08/16
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