FAQ

 

Membranes

Question: For lateral flow membranes, what is the significance of pore size?
Answer: Pore size is only a name designation. One manufacturer’s pore size designation can be quite different from another’s. Bigger pore size is designated for membranes with faster wicking rates.

Question: If pore size is only a name, how do you differentiate between different membranes?
Answer: The wicking time is an important parameter for lateral flow membranes. Membranes of designated pore size will exhibit highly repeatable wicking time.

Question: Should I block the membrane?
Answer: All membranes exhibit stable wicking rates without blocking. It is possible to make many good assays without blocking. However, should there be a need to wet block the membrane for stabilizing the Ab, reducing nonspecific reaction, or improving the migration of conjugate particles, all membranes can be blocked.

Question: Do you have detergents/wetting agents in the membrane?
Answer: NC is a hydrophobic polymer. To be able to use the NC membrane successfully it is necessary to add a small amount of detergent or a combination of detergents. The amount is so small that it does not affect the binding properties of the membrane.

Question: What is the shelf life of the membrane as received from? Is there any precaution I should take in storing the membrane?
Answer: Properly stored, NC membranes are stable for at least one year. Membrane should be kept away from heat at 40-70% R.H. Whether in roll form or in laminate format, membranes must not be allowed to lie in the open for long periods.

Question: I got a very faint shadow of false positive. I suspect the membrane.
Answer: False positive is primarily due to nonspecific binding of the conjugate particles. Using bigger pore size membrane can help reduce this, usually at the cost of sensitivity. Addition of detergents in the sample pad can also help minimize it.

Question: I get broken lines while printing the reagent line and zones where membrane does not absorb the liquid. How can the problem be resolved?
Answer: If the NC membranes are allowed to stay in the open for a few days they tend to attract hydrophobic dust particles or other moieties, which can cause above problem. Addition of 2-3% Isopropanol in the reagent formulation will help minimize above problem.

Question: How much time should I wait for the Antigen/ Antibody to bind on the membrane before an assay is run?
Answer: The binding of the protein to the NC membrane grows stronger as it is dehydrated more and more. Usually, at room temp, (20-30° C), 50-60% RH the binding will reach a maximum in 3-5 days. For development, reasonable results can be expected with overnight drying at room temperature.

Question: My tests are not stable with time. Is the membrane to be suspected?
Answer: Membrane does not affect the stability of the assay. It is related to the chemistry of the assay, and many a times it improves by adding sucrose (0.5-1.0%) to the capture Antibody solutions.

 

Sample Pads

Question: How should I select a sample pad?
Answer: The sample pad should not bind proteins nonspecifically, should exhibit good flow characteristics, and have adequate volume capacity. Its thickness should be such that it fits in the test device.

Question: Are any additives added in the sample pad and why?
Answer: Sample pads may have many additives which a user can add to achieve desired results from the assay. The additives may be blocking agents for the membrane for rapid and uniform movement of conjugate particles, buffers to control the pH and improve specificity, detergents for improved flow and reduction of false positives.


Binding Membrane

Question: Can I use the SCN membrane from any side or is there a specific side which will give better results?
Answer: Unlike other Nitrocellulose membranes available in the market, our SCN membranes offer uniform surface on both sides and give identical results.

 

Commercial

Question: What are yours production capacities?
Answer: Our has been in business for about 20 years. Thousands of sq.ft. of membrane is produced everyday. Capacities are being further expanded.

Question: How should I order? Who should I contact?
Answer: Write to us at sales@nupore.com

Question: In case of problem what support can I expect?
Answer: We will respond very quickly by assisting you in analyzing the problem and isolating the source. All shipments have retained material which is kept for 2 years. This retained material is crucial in identifying if the problem is coming from the membrane or not. Although very very rare, corrective action will follow including full replacement of the lot on priority if the problem is confirmed from the membrane.