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
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.
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.