Jerome Wenger NanoBioPhotonics

Gold nanoclusters (AuNCs) have garnered significant attention for their unique photoluminescent properties, holding large promise across a spectrum of applications. However, our understanding of their rapid photodynamics has remained elusive due to limitations posed by ensemble-averaged spectroscopy techniques.

To address this knowledge gap, we use fluorescence correlation spectroscopy (FCS) to delve into the photoluminescence dynamics of colloidal Au₁₈(SG)₁₄ nanoclusters. We address questions surrounding blinking behavior, brightness per nanocluster, and the influence of excitation power and ligands in a recent Nanoscale Advances publication. Notably, our findings reveal the distinctive quantum nature of the photoluminescence process, establishing each AuNC as an individual quantum source with a single emitting center.

In a second study published in BBA General Subjects, we combine water-soluble Au₁₈(SG)₁₄ gold nanoclusters with two organic fluorescent dyes, Alexa Fluor 647 and CF640R, presenting a ternary mixture of fluorescent emitters with nearly identical emission spectra. This work extends the capabilities of fluorescence lifetime correlation spectroscopy (FLCS) for the first time to a ternary mixture, surpassing traditional multiplexing limitations associated with distinct fluorescent dyes across the visible spectrum. Additionally, we demonstrate the suitability of gold nanoclusters for FLCS multiplexing applications, highlighting their microsecond lifetime and stable emission characteristics as valuable additions to the FLCS probe repertoire.
Our research contributes to the understanding of AuNC photodynamics, fostering the development of AuNCs in biosensing and imaging applications where single emitter resolution matters.

Both papers published open access. Open science matters.

Jerome will be co-chairman of the fourth edition of The Single-Molecule Sensors and NanoSystems International Conference which will be held in the historical center of Paris on October 28-30, 2024 at Chimie Paristech (11 rue Pierre et Marie Curie, 75005 Paris, France). Check the conference website here.

This conference brings together the leaders to discuss the most recent and exciting developments in the field of single molecules and nanosystems, covering detection and light-matter interactions from the molecular to the mesoscales.

The programme for S3IC2024 is building up fast, confirmed plenary speakers for 2024 are: Stefan Hell, Thomas Ebbesen, Philipp Tinnefeld, Philipp Kukura, Fedor Jelezko, Ronald Walsworth, Reuven Gordon, Laura Na Liu and Jeremy Baumberg. We also proudly have a very solid list of confirmed invited speakers, more on the conference website.

Important deadlines:

Early bird Submission - April 26, 2024
Early bird Registration - May 24, 2024
Submission -  July 5, 2024
Notification to authors - July 17, 2024
Registration - September 20, 2024
Conference - October 28-30, 2024

Plasmonic optical nanoantennas have revolutionized the control of light-matter interactions at the nanoscale. However, until now, their exploration has been largely restricted to the visible and near-infrared regions, overlooking the immense potential of the ultraviolet range, which boasts the strongest absorption for most molecules. In a recent ACS Nano article, entitled “Ultraviolet Resonant Nanogap Antennas with Rhodium Nanocube Dimers for Enhancing Protein Intrinsic Autofluorescence” we overcome the materials and technical limitations of UV nanophotonics and report the first experimental realization of UV resonant nanogap antennas.

Our design relies on the directed self-assembly of rhodium nanocubes into dimer nanogap antenna. We pioneer the use of rhodium as a robust alternative to aluminum, offering enhanced stability in aqueous environments and ensuring reliable UV performance. Our results demonstrate the pivotal role played by the nanogap and stand in excellent agreement with numerical simulations.

We apply the UV nanoantennas to enhance the UV autofluorescence from single label-free proteins, and achieve unprecedented enhancement factors up to 120 fold together with zeptoliter detection volumes. By enhancing the protein autofluorescence signal by up to two orders of magnitude, our results unlock powerful perspectives for local measurements of concentration, mobility, brightness, and stoichiometry of label-free proteins, circumventing the need for external fluorescent labels.

This work broadens the scope of applicability for plasmonic nanoantennas into the deep UV range, unlocking novel avenues to take maximum advantage of the strong molecular response in the UV regime.

Open access on ACS Nano website. Also available through ArXiv 2309.04152. Enjoy!

Two positions are currently open with funding from China Scholarship Council CSC and Groupe Ecoles Centrales GEC-CSC:

- One for a PhD: "Optically-controlled thermal nanotweezers to manipulate single nano-objects"

- One for a postdoc: "Deep UV optical nanoantennas to enhance the ultraviolet autofluorescence of single proteins"

Find them on the https://gec-csc.fr/ website with application form, section Natural & Life sciences: Physics & Astronomy. Application deadline January 10 2024!

We're thrilled to introduce the latest addition to our research family, Hamza Khelidj! Hamza joins our team with a passion for nanoscience and a keen interest in the development of zero-mode waveguide nanoapertures.

Hamza's expertise in nanofabrication promises to be a game-changer in our ongoing quest for cutting-edge research and innovation. We're excited to see the incredible contributions that Hamza will make to our team and to the field of nanoscience as a whole. Together, we're destined to create a future filled with breakthroughs and discoveries.