arXiv subjects

Yoann Prado

Publications and source records attributed to Yoann Prado.

2 recordsLinked to original sources

arXiv2026

Synthesis of hybrid gold-protein nanobioconjugates with strongly enhanced circular dichroism

Controlling chiral light-matter interactions with nanophotonics is a powerful strategy for amplifying molecular circular dichroism (CD) beyond its natural limits. Here, we present a plasmonic platform that uses superchiral near fields to amplify the optical activity of biological chromophores. Gold nanoparticles (3.6 nm in diameter) are electrostatically coupled with photosynthetic proteins which results in stable hybrid nanobioconjugates in aqueous solution. The Q-band absorption spectrum of the proteins overlaps with the localized surface plasmon resonance of the gold particles. In the visible region, a combination of numerical simulations and normalized CD measurements reveal an enhancement factor of 3 compared to free proteins. This observation reveals three effects. First, there is a local increase in electromagnetic chirality density in the protein environment. Second, there is an increase in the absorption of the proteins. Third, there is plasmon-induced circular dichroism. Our results quantitatively demonstrate that near-field super-chirality directly modulates biomolecular optical activity. These findings open new avenues for chiroptical nanodevices, biosensing platforms, and light-driven asymmetric photochemistry.

physics.optics↗

arXiv2024

Infrared Imaging using thermally stable HgTe/CdS nanocrystals

Transferring the nanocrystals (NCs) from the laboratory environment toward practical applications has raised new challenges. In the case of NCs for display and lightning, the focus was on reduced Auger recombination and maintaining luminescence at high temperatures. When it comes to infrared sensing, narrow band gap materials are required and HgTe appears as the most spectrally tunable platform. Its low-temperature synthesis reduces the growth energy cost yet also favors sintering. As a result, once coupled to a read-out circuit, the Joule effect aggregates the particles leading to a poorly defined optical edge and dramatically large dark current. Here, we demonstrate that CdS shells bring the expected thermal stability (no redshift upon annealing, reduced tendency to form amalgams and preservation of photoconduction after an atomic layer deposition process). The peculiar electronic structure of these confined particles is unveiled using k.p self-consistent simulations showing a significant exciton biding energy at around 200 meV. After shelling, the material displays a p-type behavior that favors the generation of photoconductive gain. The latter is then used to increase the external quantum

physics.app-ph↗