A stacking flow immunoassay for the detection of dengue-specific immunoglobulins in salivary fluid

Area of Science:

• Biomedical Engineering
• Assay Development
• Point-of-Care Diagnostics

Background:

• Paper-based immunoassays (lateral flow tests) are standard for home diagnostics.
• Salivary fluid contains high protein concentrations that cause non-specific adsorption and particle aggregation in conventional tests.
• Pre-treatment steps like filtration or centrifugation are often needed for saliva samples, complicating testing.

Purpose of the Study:

• To develop a stacking flow platform for single-step detection of target antibodies in salivary fluid.
• To overcome limitations of conventional paper-based immunoassays caused by salivary interferences.
• To enable direct saliva testing without complex sample pre-treatment.

Main Methods:

• A stacking flow platform was designed with separate paths for sample and reagent delivery.
• The platform guides samples and reagents to the test strip, removing interfering salivary substances before contact with detection reagents.
• A unique flow regulator ensures uniform flow and even test lines for improved quantification.

Main Results:

• The stacking flow platform significantly reduced background noise caused by salivary components.
• It enabled sensitive detection of approximately 20 ng/mL α-fetoprotein in serum.
• The device successfully detected dengue-specific immunoglobulins in salivary fluid.

Conclusions:

• The stacking flow platform offers a simplified, single-step approach for saliva-based immunoassays.
• This method effectively mitigates non-specific adsorption issues in complex biological fluids like saliva.
• The developed platform shows promise for accurate and convenient point-of-care diagnostics using saliva samples.