Nitrocellulose Membrane & Test Lines
What it is
The nitrocellulose membrane is where the test and control lines are immobilized — the readout zone of a lateral-flow test.
How it works
A capture antibody is dispensed at the test line and an anti-species (control) antibody at the control line. As the sample–conjugate complex flows past, it binds at the test line (proportional to analyte) and always binds at the control line (confirming the test ran correctly).
Why it matters
The control line validates each device, and test-line intensity reflects analyte level — understanding this is key to reading results and spotting invalid tests.
Key components
- Test line — capture antibody (analyte-specific)
- Control line — anti-species antibody (validity check)
- Membrane pore size — controls flow rate and line sharpness
Applications
- Immobilization of capture antibodies at test and control lines
- Substrate for capillary sample migration in lateral flow
What affects performance
- Pore size (controls flow rate)
- Coating density and line width
- Blocking (reduces nonspecific binding)
- Membrane uniformity
Limitations
- Pore-size variation affects reproducibility
- Nonspecific binding raises background
- Humidity and storage affect membrane stability
Frequently Asked Questions
What is a nitrocellulose membrane? The strip component that immobilizes capture reagents and through which the sample migrates by capillary action.
Why does pore size matter? It controls flow rate and line sharpness, which affect sensitivity and readability.
Related knowledge
References
- Posthuma-Trumpie GA, Korf J, van Amerongen A. Lateral flow (immuno)assay: its strengths, weaknesses, opportunities and threats. Anal Bioanal Chem. 2009;393(2):569-582.
- Koczula KM, Gallotta A. Lateral flow assays. Essays Biochem. 2016;60(1):111-120.
- 侧向层析标记物研究进展 (Research advance of lateral flow assay labels). Journal of Biomedical Engineering. PMC9935128.
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Written by the Progene Bio Technical Team · Last reviewed: 2026-09-12