Dear researchers,
This is my very first question here, so I feel a bit nervous.
My team consists of only undergrads who are working on the summer project.
We are aiming to detect 2 proteins (one is about 80 kDA, and another is about 160 kDA) by using lateral flow assay for each.
We are struggling with determining a suitable pore size of nitrocellulose membrane for it, even though extensive research was done and still happening. Half of the sources suggest a pore size of 0.2-0.45 µg, while other sources suggest 3-20 µg.
How to choose the proper nitrocellulose membrane?
Any advice or suggestions are highly appreciated!
For lateral flow applications, membranes are usually rated by the time it takes for the solvent to move 4cm, not by pore size. If only pore size is quoted, it probably isn’t a lateral flow membrane. ‘Fast‘ membranes might take about 75 seconds whereas slow membranes could be around 3 minutes. These times are still correlated with pore size (bigger pore, faster movement) and the range will be 3-20um (probably buried in the fine print). Slower speeds allow you to achieve lower limits of detection, as the particles and analytes have more time to interact. Faster speeds are more convenient but the performance is not as good. Often, but not always, the number within the product code refers to the number of seconds e.g. Millipore HF120 takes 120 seconds to move 4cm. A mid-range product like this might be a good place to start, or you can try fast, medium and slow products in your initial trials.
I agree with Nick Gee - Millipore HF120 is a good place to start as it's middle of the road in terms of flow rate. Most times with these types of assays it comes down to trying them out in the lab and seeing which works best in your hands.
Nick Gee and Liz Heisler, thank you very much - we appreciate your answers a lot!
The pore sizes of membranes used in this application are comparatively large, ranging from 3 to 20 μm.
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