Articles récents

Effective summary: seeing the intrinsic emission from a single natural protein with ultraviolet optical antennas

6 Avril 2022 , Rédigé par JW

One of the ultimate goals of molecular biology is to watch how single proteins work in their native state. The current mainstream approach of single molecule fluorescence relies on introducing external fluorescent markers which can lead to severe issues affecting the experimental results. As an alternative to fluorescence labelling, working in the ultraviolet is appealing to take advantage of the intrinsic autofluorescence naturally present in the vast majority of proteins. However, proteins are orders of magnitude dimmer as compared to conventional fluorescent dyes, so that single protein UV detection has remained a challenge so far. New nanotechnology tools need to be introduced to meet this challenge.

In a recent publication in Nature Communications Ultraviolet optical horn antennas for label-free detection of single proteins, our team introduces a novel optical horn antenna platform for label-free detection of single proteins in the UV with unprecedented resolutions and sensitivity. The approach combines (i) a conical horn reflector for fluorescence collection at ultrahigh angles with (ii) a metal nanoaperture for fluorescence enhancement and background screening. Real-time detection of UV autofluorescence from immobilized and diffusing single label-free proteins is demonstrated, together with experiments monitoring unfolding and dissociation upon denaturation of a widely used protein with single molecule resolution.

Optical horn antennas open up a unique new form of spectroscopy enabling the investigation of single proteins in their native state and in real time. This work provides a leap towards the design of biochemical assays with label-free single protein resolution as well as bright optical nanosources.

 

Improving single molecule fluorescence detection with metal zero-mode waveguide nanoapertures: recent developements

12 Février 2022 , Rédigé par JW

Jerome will give an invited talk at the Biophysical Society Meeting next week. For those unable to join or for those just curious about it, here is a copy of the presentation slides about using metal nanoapertures to improve single molecule fluorescence detection

 

Single-molecule Detection of Ultrafast Biomolecular Dynamics with Nanophotonics

28 Janvier 2022 , Rédigé par JW

Proteins can feature ultrafast structural dynamics in the nanosecond timescale which are very challenging to measure using conventional techniques such as single-molecule Förster resonance energy transfer (smFRET). So far, the limited fluorescence brightness and the relatively long fluorescence lifetimes have limited the temporal resolution of smFRET to the 10 ns range. Moreover, these ultrafast smFRET measurements require very long acquisition times, often above several hours.

In a recent JACS publication in collaboration with the teams of Ben Shuler and Robert Best, the nanophotonic fluorescence enhancement in zero-mode waveguides is used to push forward the smFRET measurements of ultrafast protein dynamics in the low nanosecond range. The previously inaccessible dynamics of a short intrinsically disordered peptide were probed with nanosecond FCS and smFRET, paving the way to the investigation of very rapid biomolecular dynamics.

Significance:

-    The acquisition time needed for nanosecond FCS is reduced by more than one order of magnitude. Measurements that were taking several hours can now be performed in 20 minutes.

-    The experimental data can be compared with all-atom molecular dynamics simulations, and used to further improve the accuracy of the numerical model. 

-    ZMWs from our group can be easily implemented in other labs with consistent optical performance.

 

Fast interaction dynamics of G-quadruplex and RGG-rich peptides unveiled in zero-mode waveguides

3 Janvier 2022 , Rédigé par JW

G-quadruplex structures of DNA are promising target sites for anticancer therapy. However, the interaction of G-quadruplex with proteins remains poorly understood, notably the association and dissociation kinetics.

In a recent Nucleic Acid Research publication entitled “Fast interaction dynamics of G-quadruplex and RGG-rich peptides unveiled in zero-mode waveguides”, we use 120nm nanoapertures to measure the interaction dynamics between G-quadruplexes and peptides at micromolar concentration.

Significance:

- The association and dissociation kinetics of the interaction are fully characterized for the first time and discussed in perspective of the nature and specificity of this interaction.

- Our approach using ZMW combined with FCCS-FRET opens up a new technique to investigate the previously unexplored interactions of DNA structures with a library of peptides at µM concentration. This is important to develop the antiviral and anticancer drug therapy applications involving G-quadruplexes.

Open access direct from the publisher or from our academic repository HAL.

 

Open position: contractual researcher plasmonic optical nanotweezers

12 Novembre 2021 , Rédigé par JW

We are opening a position for postdoctoral fellowship: experimental nanophotonics and plasmonic nano-optical tweezers.

Read the details and apply through the CNRS institutional website: https://bit.ly/3HiobDC

Position filled and no longer available. Contact Jerome Wenger for enquiries.

 

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