A rapid and inexpensive paper-based test for multiplexed sensing of biomarkers
The Californer/10238628

LOS ANGELES - Californer -- Centralized laboratory testing has been a standard tool for diagnosing common illnesses. However, such approach often requires expensive medical equipment and involves complex operation protocols that can only be completed within a medical facility by well-trained personnel. These requirements elongate testing time and prevent the widespread use of diagnostics in remote and resource-limited regions. To address some of these limitations, point-of-care (POC) diagnostic sensors are developed with simple and rapid operation, compact size, and low cost.

Paper-based sensors form the most common type of POC tests, often called lateral flow assays (LFAs), where the injected sample fluid flows horizontally and reacts with the specific test regions, generating, for example, a color change. Despite their advantages of simplicity and cost-effectiveness, existing LFAs have limitations, including lower sensitivity and difficulty in multiplexed testing of disease biomarkers.

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Researchers at UCLA developed a new paper-based biosensor using a fluorescent multiplexed vertical flow assay to simultaneously and rapidly quantify three cardiac biomarkers from human serum samples. The results of this new multiplexed POC sensor were published in the journal Small.

The vertical flow design of this new paper-based POC sensor enables multiple test regions with up to 100 individual test spots within a single disposable cartridge. This enables design of multiplexed diagnostics tests to simultaneously screen for multiple conditions, which increases cost-effectiveness and practicality. This powerful POC sensor operates using a small droplet of serum and has simple operation steps that a minimally trained user can perform in less than 15 min of total assay time per patient. In addition to multiplexing, this paper-based sensor also presents high sensitivity, achieving a detection limit better than ~0.5 ng/mL for each biomarker – smaller than one billionth of half a gram per milliliter of serum.

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In addition to the paper-based vertical flow assay, UCLA researchers also developed a mobile phone-based inexpensive hand-held fluorescence reader and deep learning-assisted signal analysis pipeline to automatically perform accurate quantification of the three target biomarkers in a user-friendly manner.

The researchers tested their paper-based multiplexed sensor for the quantification of three biomarkers of acute coronary syndrome (ACS). The developed paper-based sensor was tested on human serum samples, and the measured concentrations for all three cardiac biomarkers showed a good match with the ground truth measurements obtained by a standard benchtop laboratory test. With its accuracy, rapid operation, ease-of-use, and low cost, this deep learning-enabled paper-based multiplexed sensor forms an appealing POC test for various applications in remote and low-resource settings.

This research was supported by the NSF-funded Precise Advanced Technologies and Health Systems for Underserved Populations (PATHS-UP) Engineering Research Center (ERC).

Article: https://onlinelibrary.wiley.com/doi/full/10.1002/smll.202300617