Actuating whole blood and diluted blood drops


#1

Hi ,

Has anyone tried to actuate whole blood on DMF chip? I tried to actuate 1:1000 diluted blodd drop with PBS buffer. The droplet becomes immobile. Is it because of the proteins in blood plasma? It would be very helpful if anybody could share their insights on actuating blood.


#2

Hi Sam, are you using any surfactants? Without them, the device will foul instantly if there are any proteins in the sample. Using 0.1% Tetronic 90R4, we have previous moved whole blood for tens of minutes.


#3

Hi Ryan,

I really appreciate your quick reply.Thank you very much.
I have not used surfactants so far. I shall be using 0.1% Tetronic 90R4.
Glad to know that it works with whole blood as well.

What I understood from the user guide page is ,Tetronic 90R4 helps by lowering the surface tension of liquid aiding smooth actuation.To overcome non-specific adsorption, few of the publications from your group have used pluronic additives like F60 , F127 and FPEG.( latest being published in 2014. Links below.)

http://microfluidics.utoronto.ca/papers/Au_Kumar_2011.pdf
http://microfluidics.utoronto.ca/papers/AdvFunctMaterV25I4.pdf

My question is, does 0.1% Tetronic 90R4 reduces surface tension as well as non-specific adsorption?

Thanks,
Sam,


#4

Yes, both Tetronics and Pluronics are block copolymer surfactants (their chemical structures are very similar). Both families of surfactants reduce surface tension and prevent biofouling, but Tetronics 90R4 is the most effective one I know of for preventing biofouling, and is therefore what I’d recommend if you want to move blood or plasma.

We generally add it to most of our aqueous reagents as the reduced surface tension also makes it easier to load the chip.


#5

This is a much needed clarification. Thanks a lot Ryan.


#6

Hi Sam,

As Ryan mentioned, try using 0.05 to 0.1 % 90R4. I have been using it to move whole blood and diluted blood with no issues. Also if you load undiluted blood, make sure you don’t leave it sitting in the the reservoir for too long, it evaporates and creates a film that will just make your life hard when dispensing.


#7

Hi Alex,

Thank you for your inputs.
It would be very helpful if you could share any info on the status of blood cells after actuation in presence of Tetronic-90R4.

@ryan
Any observations/ insights on the condition of blood cells after actuation in presence of Tetronic-90R4?


#8

Hi Sam,

We screened various concentrations of Tetronic 90R4 in whole blood and did not observe hemolysis below concentrations of 0.2% w/w.