Stacking pads made of cellulose and glass fiber conjugate pad are used for the conjugate transfer process. These two types of material differ greatly in their density and pore sizes, with the former having the lowest permeability. The high pore size of the cellulose-based materials is thought to increase the elution time of the protein A spiked in PBS buffer solution. The low-density pads are ideal for sample release, while the high-density ones are suitable for precision assays.
Stacking pads were manufactured using a polymer matrix containing AuNP. The resulting monoclonal antibody is called polyclonal anti-Protein A. The additional stacking pad was a 4 mm x 4 mm paper-based material with a 1 mm overlap between the test pad and the conjugate pad. All components were assembled according to the design shown in Fig. 1(b).
The next step in the conjugate assay is the treatment of the conjugate pad. The blocking buffer must be optimized for each lateral flow assay. To perform this, the pads should be thoroughly cleaned and treated. Using an automated dispenser can also help. Achieving a uniform coating will increase the intensity of the response signal. These two methods can be used to improve the performance of lateral flow assays. These results are comparable to those of a conventional LFIA test.
The next step was to prepare the conjugate test. A 10 mL polyclonal anti-Protein A and goat anti-mouse IgG antibody were mixed together and loaded on the test pad. The conjugate solution was added to the sample pad. Then, the resulting strips were examined for the presence of AuNP-antibody. A total of 10 mL AuNP-antibody conjugate was added to the conjugate test pad and the sample.
Besides the cellulose-based SG1 pad, the glass fiber-based SG1 membrane demonstrated comparable performance in the LFIA test. However, the polyester-based SP1 stacking pad did not improve sensing results and reduced the signal at the T-line. Therefore, the cellulose-based substrate SC1 exhibits superior performances. While the polyester-based SP1 stacking pad failed to improve the sensoring results, it had a similar effect on the T-line.
To improve the performance of lateral flow assays, the SG1 cellulose substrate displayed the best performance. The intensity of the response signal increased by almost 2-fold. The glass fiber-based SG1 pad demonstrated comparable performance in the LFIA test. Despite the polyester-based membrane, SG1 exhibited the same results as the conventional LFIA test. A polyester-based SG1 stacking pad did not improve the sensing results.
LFA strips were used to improve the detection limit of the colorimetric test. LFA strips were tested with different membrane materials. The cellular compositions of the samples were different for the LFA-SFA tests. To optimize the lateral flow assay, a glass fiber conjugate pad was employed. It is important to properly dry the conjugate on the pad to ensure its long-term stability. In addition, a conjugate pad is used for the lateral flow assay.
The sample pad is an essential component of paper-based LFAs. Its function is to control the release of the gold conjugate from the sample after evaporation. Other common materials used in the manufacture of sample pads include cellulose fiber. These materials are inexpensive and environmentally friendly. Many companies use cellulose fiber to absorb blocking agents, release agents, and pH and ionic strength modifiers. This is an inexpensive, efficient way to create a gold conjugate.
The conjugate pad is generally made from non-woven fibers and is fabricated by compressing the fibers. It is usually made of cellulose, glass, polyester, or polypropylene. The material used to make the pads has different thicknesses and can be colored by adding various dyes, enzymatic or fluorescent agents, or viscosity enhancers. The pH and ionic strength modifiers are commonly added to the sample pad to provide different spectral properties.
The conjugate pad material may be a paper, polyester, glass fiber, or polyethylene membrane. The dyes are lyophilized and can be latex microparticles, fluorescent, and radioactive. After evaporation, the eluate is loaded onto the gold conjugate pad. A semi-permeable membrane is placed underneath the sample pad and over the conjugate pad. The test results are immediately analyzed, and the optimal sample buffer and dilution conditions are chosen based on the visual inspection of the control and test lines.
The LFSA is designed to be used in a lab setting. The LFSA contains three overlapping pads: a gold conjugate pad, a nitrocellulose membrane pad, and an absorption pad. After immersing the sample pad, it is subjected to a solution of 0.01 M PBS, 3% BSA, and 0.05% Tween20. After evaporation, the sample pad is immersed in a solution containing 5% BSA, 1% sucrose, and 1% PEG20000.
The conjugate pad is a versatile product with multiple uses. It can be used in a laboratory setting where a small sample is required. It can be made of different materials and colors, which can be used to differentiate between different samples. The sample pad is a flexible, plastic material that allows for easy handling. Unlike paper, it can be easily laminated to various substrates. A single conjugate pad is a good choice for this application.
The sample pad is a paper-based material that has been coated with a coating of gold nanoparticles. The sample pad is inserted into the test tube, and the conjugate pad is then flipped up onto it. The gold-coated ligand is mixed with the conjugate pad. This mixture is known as a chromatogram. However, a single color is not representative of a whole population.
A gold conjugate pad is a great choice for lateral flow assays. Its pore size helps the conjugate release from the pad. The pore size determines how well the gold conjugate will bind to the sample. The more pore size, the better, as this will allow for more accurate results. The gold conjugate pad should not be used for immunoassays. It should be used for lateral flow assays.