On-demand COMmunication between fluorescent organic nanoparticles through Energy Transfer

Project Information

COMET

Grant agreement ID: 101077364

DOI

10.3030/101077364

EC signature date 9 December 2022

Start date 1 February 2023

End date 31 January 2028

Funded under

• European Research Council (ERC)

Total cost

€ 1 500 000,00

EU contribution

€ 1 500 000,00

Coordinated by

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
France

Periodic Reporting for period 1 - COMET (On-demand COMmunication between fluorescent organic nanoparticles through Energy Transfer)

Reporting period: 2023-02-01 to 2025-07-31

Summary of the context and overall objectives of the project

The detection of biologically relevant molecules directly in complex media, such as blood or interstitial fluid, remains a significant challenge in bioanalytical science. To enable real-time, in situ monitoring of target analytes, there is an urgent need for sensitive, selective, and robust biosensing tools. COMET aim at addressing this challenge by developing a new generation of optical biosensors based on fluorescent organic nanoparticles (FONs), offering an innovative approach for the ultrasensitive detection of drugs.

Fluorescent nanoparticles have emerged as promising candidates for biosensing due to their high brightness and stability. However, most existing systems rely on inorganic materials that pose limitations in terms of toxicity, biodegradability, and chemical versatility. In contrast, COMET pioneers the use of fully organic, water-compatible FONs as both energy donors and acceptors, enabling the design of biosensors that should not only be highly efficient and non-toxic, but also capable of long-range inter-particle communication via Förster Resonance Energy Transfer (FRET).

The core objective of COMET is to create nanoscale architectures where FONs communicate optically in a controlled and stimulus-responsive manner. These nanoassemblies will integrate molecular recognition units (e.g. oligonucleotides) that respond to the presence of specific drug molecules by triggering changes in FRET efficiency, thereby amplifying the fluorescence signal. This mechanism will allow for label-free, ratiometric, and continuous detection of target compounds with unprecedented sensitivity.

To achieve this, COMET will:

Develop new self-assembled FONs with tailored core-shell structures

Engineer nanoconstructions capable of controlled energy transfer between donor and acceptor FONs

Demonstrate their application in real-time biosensing of drugs

COMET's interdisciplinary approach, combining chemistry, materials science, and biology, also exemplifies the integration of physical and life sciences in addressing urgent societal needs.

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

During the initial phase of the COMET project, significant progress was made in designing and synthesizing innovative fluorescent organic nanoparticles (FONs) for biosensing applications. The work focused primarily on the development of compact and functional FONs and the study of energy transfer between nanoparticles.

– Synthesis of Functional FONs:

Two complementary strategies were explored to create water-stable, bioconjugatable FONs:

- Post-functionalization of dyes :
In this approach, fluorescent dyes were chemically modified to include reactive groups such as maleimides, which enable easy attachment of biomolecules. These modified dyes were then nanoprecipitated into small (~20 nm), water-stable FONs. Notably, these particles displayed a fluorogenic behavior—switching on fluorescence in the presence of thiols—making them promising probes for detecting intracellular or extracellular thiols. This work resulted in a peer-reviewed publication (Dal Pra et al., Small Methods, 2024).

- Synthesis of polymeric nanoparticles:
we are currently exploring new routes of polymer synthesis to obtain small, bright and functionalizable nanoparticles.

- Nanophotonics: While the custom-made FONs required for this task are still being finalized, all researchers involved in the project have been actively characterizing the optical properties (absorption, emission, quantum yield) of the particles they are developing. To support early testing, a postdoctoral researcher was hired to synthesize and functionalize known FONs, to begin early experiments on FRET between nanoparticles.


COMET is currently creating compact, water-stable FONs that are chemically versatile and capable of selective bioconjugation. Some of the nanoparticles exhibit fluorogenic behavior, lighting up in the presence of thiols, and were demonstrated as sensitive probes for detecting intracellular and extracellular biomolecules. We are developping innovative synthesis strategies to obtain fluorescent core-shell polymeric nanostructures.While the full donor–acceptor FON assemblies are still under optimization, early studies and tool development have advanced understanding of inter-particle energy transfer mechanisms.

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)

COMET has delivered key advances that significantly extend the current boundaries of nanophotonics and biosensing. Notably, the project has demonstrated the feasibility of using fully organic, water-stable fluorescent nanoparticles (FONs) not only as biotrackers, but as active components in biosensing platforms—a transformative step in the field of bioimaging and diagnostics.

Two scientific publications have emerged from the project so far, with more in preparation. Among them, the work by Dal Pra et al.—published in Small Methods—was selected for the “Celebrating Excellence in the Advanced Materials Family: Women in Materials Science” collection. This recognition underscores the originality and impact of the research. The article illusrate how FONs can be engineered to exhibit fluorogenic behavior, selectively lighting up in response to thiol-containing biomolecules. This discovery enables their use not only in visualizing biological environments, but also as real-time sensors of biochemical activity—bringing the concept of “smart” nanoparticles into practical focus.

These findings push beyond the state of the art by: Demonstrating fluorogenic organic nanoparticles responsive to biologically relevant triggers / Developing novel synthesis routes for bioreceptor-functionalized FONs using gentle, aqueous, one-pot reactions;

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