transferred to the conjugated pad in smooth and continuous manner. Sometimes,
pre-treatments like the separation of the components of the sample, adjustment of
pH are also necessary before the transport of the sample [15]. To increase the
sensitivity of these pads they should be well treated with appropriate buffers,
blocking agents and other reagents.
Conjugate Pad. The conjugate pad is composed of cellulose, Polyesters etc.
Biorecognition molecules i.e. antibodies are modified at the conjugated pad zone.
When sample is transported from sample pad to conjugated pad, these antibodies
are released upon contact with the sample. To maintain homogeneity of the pad
pre-treatment is required, where the conjugated pad needs to be properly dispensed
and hydrophilic materials used in these pads give better flow rates.
Nitrocellulose membrane. Nitrocellulose membrane is a porous membrane with
pore size ranges from 0.05 to 12 lm. It is also known as reaction membrane which
carries the test and control lines. These lines are modified with specific biological
components (usually antibodies or antigen) to detect the target analyte. The sample
is wicked through the membrane and responses appear at the control and test lines.
Substances bind to the membrane through hydrogen bonding, hydrophobic and
electrostatic interactions. The sensitivity of lateral flow assay is highly based on the
suitable modifications at the nitrocellulose membrane. There are other important
factors which further affect the sensitivity of nitrocellulose membrane. For example,
proper dispensing and drying of the membrane is crucial. In addition, non-specific
adsorption and humidity are other vital factors, which need to be controlled.
Adsorbent pad. It is present at the end of the strip and basically prevents the
backflow of the sample. The result assay is largely affected by the properties of the
adsorbent pad as false positive result can be obtained if there is a backflow of the
fluid. High-density cellulose is preferred for the wicking material [16]. Proper
assembling of all these components is done over a backing card. It provides support
so that the strip could be easily handled.
Fig. 1 Components of a immunochromatographic strip (ISC)
Immunochromatographic Strip Based Sensor for the Detection …
235
pre-treatments like the separation of the components of the sample, adjustment of
pH are also necessary before the transport of the sample [15]. To increase the
sensitivity of these pads they should be well treated with appropriate buffers,
blocking agents and other reagents.
Conjugate Pad. The conjugate pad is composed of cellulose, Polyesters etc.
Biorecognition molecules i.e. antibodies are modified at the conjugated pad zone.
When sample is transported from sample pad to conjugated pad, these antibodies
are released upon contact with the sample. To maintain homogeneity of the pad
pre-treatment is required, where the conjugated pad needs to be properly dispensed
and hydrophilic materials used in these pads give better flow rates.
Nitrocellulose membrane. Nitrocellulose membrane is a porous membrane with
pore size ranges from 0.05 to 12 lm. It is also known as reaction membrane which
carries the test and control lines. These lines are modified with specific biological
components (usually antibodies or antigen) to detect the target analyte. The sample
is wicked through the membrane and responses appear at the control and test lines.
Substances bind to the membrane through hydrogen bonding, hydrophobic and
electrostatic interactions. The sensitivity of lateral flow assay is highly based on the
suitable modifications at the nitrocellulose membrane. There are other important
factors which further affect the sensitivity of nitrocellulose membrane. For example,
proper dispensing and drying of the membrane is crucial. In addition, non-specific
adsorption and humidity are other vital factors, which need to be controlled.
Adsorbent pad. It is present at the end of the strip and basically prevents the
backflow of the sample. The result assay is largely affected by the properties of the
adsorbent pad as false positive result can be obtained if there is a backflow of the
fluid. High-density cellulose is preferred for the wicking material [16]. Proper
assembling of all these components is done over a backing card. It provides support
so that the strip could be easily handled.
Fig. 1 Components of a immunochromatographic strip (ISC)
Immunochromatographic Strip Based Sensor for the Detection …
235