Gold-Functionalized Devices and Engineered Nanoparticles: Bioorthogonal Tools for Unprecedented Biomedical Applications

Project Information

GOLDEN

Grant agreement ID: 841990

DOI

10.3030/841990

Project closed

EC signature date 12 April 2019

Start date 7 October 2019

End date 6 October 2021

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 212 933,76

EU contribution

€ 212 933,76

Coordinated by

THE UNIVERSITY OF EDINBURGH
United Kingdom

Periodic Reporting for period 1 - GOLDEN (Gold-Functionalized Devices and Engineered Nanoparticles: Bioorthogonal Tools for Unprecedented Biomedical Applications)

Reporting period: 2019-10-07 to 2021-10-06

Summary of the context and overall objectives of the project

The research program originated from the need for developing a safe therapeutic technology capable of mediating localised release of drugs exclusively at a damaged (non-cancerous) tissue or organ and for extended periods of time. The EU-funded GOLDEN project proposed to bypass the metabolic machinery of cells and produce bioactive molecules at specific locations within the body using metallic nanoparticles (NPs). Gold-based NPs serve as biocompatible catalysts and can be engineered to trigger release of systemically administered bioactive precursors into drugs (psychoactive agents). In this project, we used zebrafish as a model to test the efficacy of the GOLDEN NP-based strategy at activating dyes and neuromodulators in the brain, paving the way for the treatment of localised disorders and chronic pain.

To achieve this, we developed a suite of chemical tools designed to optimize the catalytic property of Au-based devices, to mediate the release of a neuroactive agent directly in the brain of an animal, eventually reducing the adverse effects of systemic administration. Therefore, the main objectives were:
1. Development of Au-functionalized nanoparticles and microimplants with optimal catalytic capacity in biological media.
2. Development of inactive (caged) precursors of psycho-stimulants or depressants that are rapidly uncaged by Au catalysis in biocompatible conditions.
3. In vivo validation of the technology by testing its capacity to ―safely― increase or reduce zebrafish locomotor activity by intracranial release of psychoactive agents.

Thanks to the successful completion of this research project, we reported the development of a truly-catalytic Au-polymer composite by assembling ultrasmall Au-NPs at the protein-repelling outer layer of a co-polymer scaffold via electrostatic loading. The developed bioorthogonal Au-based catalysts, coupled with activatable precursors of drugs/dyes, enabled the in situ generation of imaging and therapeutic agents. Expanding the scope of Au chemistry is paving the way to more advanced technologies and, in turn, is fostering the creation of first-in-class theranostic strategies to address unmet clinical needs. In addition, illustrating the in vivo-compatibility of the novel catalysts, we showed their capacity to uncage the anxiolytic agent fluoxetine at the central nervous system (CNS) of developing zebrafish, influencing their swim pattern. However, not only is it a safe method for the generation of bioactive compounds in designated anatomical areas, but this bioorthogonal strategy has enabled ―for the first time― modification of cognitive activity by releasing a neuroactive agent directly in the brain of an animal, offering a route for new applications beyond treating cancer or inflammation.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The objectives and goals of the project were addressed via three specific Work Packages (WPs): (WP1)Preparation & catalytic testing of Au-based nanoparticles and microimplants; (WP2)Development and bioorthogonal activation of caged agents in cell culture; and (WP3)In vivo bioorthogonal catalysis. Exploration of new biomedical applications.
Building on previous work from the host laboratory(Unciti-Broceta group), the optimization of the protocol for the preparation of Au-implants was the first purpose that was completed in the project. Then, partially overlaid with WP1, synthetic routes for the preparation of the chemical tools (e.g. prodye/pro-neuromodulators) and catalytic/conversion studies well-established in the host lab were performed in parallel. After the completion of these studies the goals settled in WP2 were achieved. Finally, after verification that the Au-implants are safe and that they are capable of generating bioactive compounds in vitro and in cell culture, training and experimentation of WP3 were initiated. In vivo experiments were performed in collaboration with Prof Becker (Director of Centre of Discovery Brain Sciences at University of Edinburgh). The most innovative experiment of WP3 was the behavioural assay in the zebrafish model, whose setting up and preliminary testing have been essential results for the proof of concept of the project proposed.
As an overview of the results, we have developed a novel Au-based heterogeneous catalyst that is fully compatible with living systems, both in terms of safety and functionality. To achieve this, a novel loading strategy was implemented to increase the abundance of active metal centers at the outer layer of a polymer scaffold. The properties of the Au-microimplants were tested in vitro and in vivo with a new Au-activatable fluorescence precursor. Finally, with the aim of exploring new biomedical applications, we have shown that the swimming behavior of zebrafish embryos can be modulated by the bioorthogonal release of an anxiolytic agent directly in their head, something never achieved before with bioorthogonal tools.
For exploitation purposes, this proof-of-concept study demonstrates that Au catalysts can mediate abiotic reactions at neural networks without causing harm or interfering with the complex biochemistry of this sensitive environment, making it a true vivo-compatible catalyst. This project expands the scope of Au chemistry and vivo-orthogonal catalysis, offering a new methodology to study neurological function by producing bioactive agents exclusively at the brain of zebrafish (thus avoiding the noise produced at the peripheral nervous system).
The results of the project were disseminated in two scientific publications, where a reference to EU funding is included.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Such a safe method for the generation of bioactive compounds in designated anatomical areas is a novel theranostic strategy to address unmet clinical needs. Although acknowledging that this research work was preliminary in nature and was not designed to directly address human disease, it will provide fundamental insights into the clinical scope of Au chemistry as a platform technology to control the safe manufacture of chemicals in the most complex physiological settings. The results demonstrate that suitably-protected gold nanocatalysts can mediate abiotic reactions at neural networks without causing harm or interfering with the complex biochemistry of this sensitive environment, offering for the first time a route for new applications beyond treating cancer or inflammation. Importantly, the completion of this approach developed in the project provides a new methodology to study neurological function by generating neuroactive agents directly in the brain of an animal without systemic side effects. From the point of view of medical practice, given the possibility to translate this strategy to peripheral damaged nerves (outside the brain), this research opens up a future route to treat localized neurological disorders, such as neuropathic pain. That is to say, by employing a safe strategy that localizes the intervention at the peripheral nerves, and thereby avoid the psychotropic side effects of current treatments, which include sedation, addiction, depression or increased risk of committing suicide. Therefore, this innovation will both reduce systemic toxicity, time and treatment improvement, impacting on the reduction of the health and the economic burden of health care, as well as boost its adoption by the pharmaceutical industry, driving to its commercial success. The opioid crisis in the US is an example of the negative impact of current drugs in the treatment of pain.

Making psychoactive drugs directly in the brain