Single Molecule Processes
This new group at ITQB is focussed on the study of chemical and biochemical processes at the single molecule level. Observing a single molecule and its stochastic interactions with another gives a bottom up understanding of bulk chemistry. While bulk chemistry relies on the notion of equilibrium, single molecule processes know no such thing.
Yann Astier | Research InterestsSelected PublicationsProcessos de Moléculas Isoladas (PT) | ||
Phone (+351) 214469721 | |
Research Interests
Nanopores are emerging as very efficient single molecule sensors.[1,2] They represent a promising technology in the field of single molecule unlabelled DNA sequencing.[3] The mechanical robustness, nanometer range precision, and rigidness of synthetic nanopores promise an easier integration into sensing technology when compared to membrane embedded nanopores. Synthetic nanopores (2 to 8 nm in diameter) produced out of Si3N4 membranes,[4] have found several applications in biophysics, such as characterization of DNA duplexes by electromechanical unzipping, detection of DNA/protein complexes, and characterization of proteins and DNA.[5-10]
We show the use of functionalized Si3N4 nanopore (3.2 to 6.5 nm in diameter, 30 and 50 nm in length) for the detection of negatively charged gold nanoparticles from 2.4 to 8.9 nm diameter (Figure 1). We find that we can detect the interaction through ionic current alterations, whether the electric field driven nanoparticle threads through the pore or not. Our simulation work suggests that weak force interactions are essential to create the initial nanoparticle nanopore interaction. Once a nanoparticle is engaged into the nanopore, Brownian motion theory fits our off data. We also show how artificial nanopores are a viable single particle screening tool to assess the size distribution of particles under 4 nm in diameter.
Gold nanoparticles coated with a self-assembled monolayer (SAM) of thiolated molecules are promising materials for many applications ranging from electronics to nanomedicine.[11,12] The ligand shell is the key in determining the interfacial properties of the particles.[13,14] These particles unfortunately are very often polydisperse in size, ligand shell composition, and probably morphology.[15] Hence the determination of their properties is always limited by bulk averaging. A method able to sort and characterize these particles sensitive to both their size and their interfacial (i.e. ligand shell) properties would help the field progress. The nanopore detection scheme presented here is a first step in that direction as it characterizes particles size and ligand shell on a single particle basis.
Selected Publications
- Oktay Uzun, Francesco Stellacci, Yann Astier*.” Single Gold Nanoparticle Capture and Release by the α-Hemolysin Protein Nanopore” Small (2009), 5(11), 1273-1278.
- Yann Astier, Orit Braha, Hagan Bayley, “Towards single molecule DNA sequencing: direct identification of 5’ monophosphate ribo and deoxy-ribo nucleotides with a protein nanopore equipped with a molecular adapter.” J. Am. Chem. Soc. (2006), 128(5) 1705-1710
- Haichen Wu, Yann Astier, Giovanni Maglia, Ellina Mikhailova and Hagan Bayley “α-Hemolysin pores with covalently attached molecular adapters” J. Am. Chem. Soc.(2007), 129 (51), 16142 -16148
Laboratory´s website
For futher information visit the laboratory's website
Processos de Moléculas Isoladas (PT)
Este novo grupo do ITQB concentra-se no estudo de processos químicos e bioquímicos ao nível de moléculas isoladas. Observando uma única molécula e as suas interacções estocásticas com outras moléculas podemos compreender, da parte para o todo, a química macroscópica. Enquanto que esta assenta na noção de equilíbrio, os processos de moléculas isoladas desconhecem tal conceito
