Capping-Agent Regulation of Exciton Transport in Organic Nanoparticles Enables Ultrabright Flow Cytometry Probes
6 affiliations
- 1Nano-Science Center and Department of Chemistry
- 2University of Copenhagen
- 3Extreme Light Infrastructure ERIC, ELI Beamlines Facility, Dolní Břežany 252 41, Czech Republic
- 4Department of Chemistry
- 5Indiana University
- 6Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, Copenhagen, Denmark, DK-2100
Abstract
Fluorescent dye-loaded nanoparticles (NPs) offer powerful platforms for bioimaging, biosensing, and flow cytometry, but their performance is often compromised by aggregation-caused quenching and exciton trapping. Although molecular isolation can suppress aggregation, controlling exciton transport within fluorescent NPs remains challenging. Here, we demonstrate that the capping agent provides a powerful means to regulate exciton dynamics in small-molecule ionic isolation lattice (SMILES) NPs. Replacing the conventional phospholipid capping agent DSPE-PEG with poly(styrene-co-maleic anhydride) (PSMA) increases the fluorescence quantum yield more than threefold, reaching 61%. Polarization-resolved femtosecond transient absorption spectroscopy reveals markedly slower exciton depolarization with PSMA, with the anisotropy remaining at ~0.1 at long delay times, indicating restricted exciton migration and reduced trapping at nonradiative defects. This exciton confinement enhances fluorescence efficiency and substantially increases NP brightness. The capping-agent-dependent regulation of exciton transport is applicable to structurally diverse fluorophores, enabling SMILES NPs with distinct emission colors spanning the visible to near-infrared spectral range. Following antibody functionalization, these ultrabright NPs produce fluorescence signals up to 17-fold higher than commercial phycoerythrin-conjugated antibodies in flow cytometry of human peripheral blood. These findings establish capping-agent regulation of exciton transport as a general approach to enhancing the brightness and analytical performance of fluorescent nanoprobes.
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BibTeX
@misc{zhang2026cappingagent,
title = {{Capping-Agent Regulation of Exciton Transport in Organic Nanoparticles Enables Ultrabright Flow Cytometry Probes}},
author = {Fuxue Zhang and Jakub Dostá and Andrej Hovan and Miroslav Kloz and Amar H. Flood and Elisabeth Rexen Ulven and Bo W. Laursen and Junsheng Chen},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008155/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008155/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Capping-Agent Regulation of Exciton Transport in Organic Nanoparticles Enables Ultrabright Flow Cytometry Probes
AU - Fuxue Zhang
AU - Jakub Dostá
AU - Andrej Hovan
AU - Miroslav Kloz
AU - Amar H. Flood
AU - Elisabeth Rexen Ulven
AU - Bo W. Laursen
AU - Junsheng Chen
PY - 2026
DA - 2026/09/01
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008155/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008155/v1
AB - Fluorescent dye-loaded nanoparticles (NPs) offer powerful platforms for bioimaging, biosensing, and flow cytometry, but their performance is often compromised by aggregation-caused quenching and exciton trapping. Although molecular isolation can suppress aggregation, controlling exciton transport within fluorescent NPs remains challenging. Here, we demonstrate that the capping agent provides a powerful means to regulate exciton dynamics in small-molecule ionic isolation lattice (SMILES) NPs. Replacing the conventional phospholipid capping agent DSPE-PEG with poly(styrene-co-maleic anhydride) (PSMA) increases the fluorescence quantum yield more than threefold, reaching 61%. Polarization-resolved femtosecond transient absorption spectroscopy reveals markedly slower exciton depolarization with PSMA, with the anisotropy remaining at ~0.1 at long delay times, indicating restricted exciton migration and reduced trapping at nonradiative defects. This exciton confinement enhances fluorescence efficiency and substantially increases NP brightness. The capping-agent-dependent regulation of exciton transport is applicable to structurally diverse fluorophores, enabling SMILES NPs with distinct emission colors spanning the visible to near-infrared spectral range. Following antibody functionalization, these ultrabright NPs produce fluorescence signals up to 17-fold higher than commercial phycoerythrin-conjugated antibodies in flow cytometry of human peripheral blood. These findings establish capping-agent regulation of exciton transport as a general approach to enhancing the brightness and analytical performance of fluorescent nanoprobes.
ER -