. Author manuscript; available in PMC: 2019 Nov 26.

Published in final edited form as: Chem Soc Rev. 2018 Nov 26;47(23):8512–8524. doi: 10.1039/c8cs00106e

Table 2.

The possible events inside a nanopore as a protein molecule enters.

Events	Signal Characteristics	Events	Signal Characteristics

Fully-intact, Smooth translocation	Deep event amplitude	Collision	Shallow events
	• Increase voltage/shorter dwell time		• Increase voltage/longer dwell time³⁸

Adsorption to a pore’s wall (non- specific interaction)	Deep events, millisecond-to second long	Specific interaction with the pore’s wall	Deep events, millisecond-to second long ⁸
• Adsorption • Electrostatic interaction	• Reduce adsorption by pre- treating the pore wall with a lipid or a surfactant^37,38 • Change pH	• ligand on the pore’s wall

Tumbling inside a pore	Strong intra-event signal fluctuation, two preferred levels^9,10	Binding/Unbinding	Well defined sub-levels
	• Introduce strongly-charged tag like a short oligo^4,11	• Due to coupling with other molecules (eg. enzyme substrates)

Conformational change (transient)	Contribute to the width of the event amplitude histogram	Unfolding	Shallow events
• May be induced by the pore’s electric field or physical confinement		• Induced by the pore’s electric field or physical confinement • Introducing denaturants	• Introduce denaturing agents such as SDS or urea • Increase voltage/ shorter dwell time^11,12,41