How do I deal with a partial nanopore blockage during a recording?

Most of the issues relating to partial blocking of nanopores can be minimised with thorough care during sample preparation - using clean tubes, filtered fresh electrolyte and Izon qEV columns to isolate EVs. However, bubbles and contamination may lead to partial blocking of the nanopore.

 

A good measurement should consist of a run that has a stable baseline current which meets these requirements: 

  • Signal trace largely horizontal (current drift is 1% per minute)
  • RMS noise of < 15 pA (blockade magnitude should lie above the orange RMS noise line, ideally in the green zone) 
  • Minimum particle count of 1000. 

 

Should you come across a partial blockage during a measurement run:

  1. Pause the measurement when a blockage occurs to avoid measurement inaccuracies.
  2. Follow the flowchart to recover baseline current:

    User may "click" the fluid cell cap (Fluid Cell Cap) into place to stabilise baseline current. Be aware that over-clicking can irreversibly damage the nanopore.

  3. Once the baseline current has been recovered, apply the same pressure and resume recording.
  • If the above steps don't recover the baseline current, start the nanopore setup sequence again either with the same or a new nanopore.
  • Consider changing the sample's concentration or make up a brand new sample.
  • For some particles that are prone to blocking (more than 3 times per measurement/pressure), consider increasing nanopore stretch or use a larger nanopore. 

If the above suggestions don't resolve the issue, contact Izon Support