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Nanofluidic Traps by Two-Photon Fabrication for Extended Detection of Macromolecules and Colloids in Solution

Accepted version
Peer-reviewed

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Authors

Vanderpoorten, Oliver 
Babar, Ali N 
Jacquat, Raphael PB 
Challa, Pavan K 

Abstract

The analysis of nanoscopic species, such as proteins and colloidal assemblies, at the single-molecule level has become vital in many areas of fundamental and applied research. Approaches to increase the detection timescales for single molecules in solution without immobilising them onto a substrate surface and applying external fields are much sought after. Here we present an easy-to-implement and versatile nanofluidics-based approach that enables increased observational-timescale analysis of single biomacromolecules and nanoscale colloids in solution. We use two-photon-based hybrid lithography in conjunction with soft lithography to fabricate nanofluidic devices with nano-trapping geometries down to 100 nm in height. We provide a rigorous description and characterisation of the fabrication route that enables the writing of nanoscopic 3D structures directly in photoresist and allows for the integration of nano-trapping and nano-channel geometries within micro-channel devices. Using confocal fluorescence burst detection, we validated the functionality of particle confinement in our nano-trap geometries through measurement of particle residence times. All species under study, including nanoscale colloids, α-synuclein oligomers, and double-stranded DNA, showed a three to five-fold increase in average residence time in the detection volume of nano-traps, due to the additional local steric confinement, in comparison to free space diffusion in a nearby micro-channel. Our approach thus opens-up the possibility for single-molecule studies at prolonged observational timescales to analyse and detect nanoparticles and protein assemblies in solution without the need for surface immobilisation.

Description

Keywords

nanoparticle trapping, nanofluidics, 2-photon lithography, protein oligomers, DNA, molecular trapping, confocal fluorescence detection, soft lithography

Journal Title

ACS APPLIED NANO MATERIALS

Conference Name

Journal ISSN

2574-0970
2574-0970

Volume Title

Publisher

ACS
Sponsorship
Horizon 2020 programme (766972-FET-OPEN-NANOPHLOW); EPSRC EP/L015889/1; Horizon 2020 Framework Programme through the Marie Sklodowska-Curie grant MicroSPARK (agreement n◦ 841466;, the Herchel Smith Funds, and the Wolfson College Junior Research Fellowship