High-throughput nanofluidic device for one-dimensional confined detection of single fluorophores

Abstract

Ensemble averaging experiments may conceal many fundamental molecular interactions. To overcome that, a high-throughput detection of single molecules or colloidal nanodots is crucial for biomedical, nanoelectronic, and solid-state applications. One-dimensional (1D) discrete flow of nanoscale objects is an efficient approach in this direction. The development of simple and cost-effective nanofluidic devices is a critical step to realise 1D flow. This letter presents a nanofabrication technique using shadow-angle-electron-beam-deposition for a high-throughput preparation of parallel nanofluidic channels. These were used to flow and detect DNA, carbon-nanodots, and organic fluorophores. The 1D molecular mass transport was performed using electro-osmotic flow. The 1D flow behaviour was identified and analysed using two-focus fluorescence correlation spectroscopy (2fFCS). A range of flow velocities of single molecules was achieved. The transitions of single molecules or nanodots through the two foci were quantitatively analysed using confocal scanning imaging, correlative photon detection, and burst size distribution analysis. The results suggest an efficient nanofabrication technique is developed to prepare nanofluidic devices. This first demonstration of high-throughput nanochannel fabrication process and using 2fFCS-based single molecule flow detection should have a potential impact on ultra-sensitive biomedical diagnostics and studying biomolecular interactions as well as nanomaterials.