A device architecture for three-dimensional, patterned paper immunoassays

Abstract

Diagnostic assays can provide valuable information about the health status of a patient, which include detection of biomarkers that indicate the presence of an infection, the progression or regression of a disease, and the efficacy of a course of treatment. Critical healthcare decisions must often be made at the point-of-care, far from the infrastructure and diagnostic capabilities of centralized laboratories. There exists an obvious need for diagnostic tools that are designed to address the unique challenges encountered by healthcare workers in limited-resource settings. Paper, a readily-available and inexpensive commodity, is an attractive medium with which to develop diagnostic assays for use in limited-resource settings. In this article, we describe a device architecture to perform immunoassays in patterned paper. These paper-based devices use a combination of lateral and vertical flow to control the wicking of fluid in three-dimensions. We provide guidelines to aid in the design of these devices and we illustrate how patterning can be used to tune the duration and performance of the assay. We demonstrate the use of these paper-based devices by developing a sandwich immunoassay for human chorionic gonadotropin (hCG) in urine, a biomarker of pregnancy. We then directly compare the qualitative and quantitative results of these paper-based immunoassays to commercially available lateral flow tests (i.e., the home pregnancy test). Our results suggest paper-based devices may find broad utility in the development of immunoassays for use at the point-of-care.

Comparison of three indirect immunoassay formats on a common paper-based microfluidic device architecture

“…26 In comparison to paper-based ELISA approaches, three-dimensional paper-based microfluidic devices facilitate faster assays (ca. 26 In comparison to paper-based ELISA approaches, three-dimensional paper-based microfluidic devices facilitate faster assays (ca.…”

“…26 While paper-through the stacking 27 or folding of layers 28 -offers the possibility of multiplexed assays by spatially separating reagents in parallel fluidic networks within a single device, traditional lateral flow immunoassays currently offer a considerable advantage by using a common device architecture (i.e., dipstick design). 26 While paper-through the stacking 27 or folding of layers 28 -offers the possibility of multiplexed assays by spatially separating reagents in parallel fluidic networks within a single device, traditional lateral flow immunoassays currently offer a considerable advantage by using a common device architecture (i.e., dipstick design).…”

“…26 However, to facilitate the development of HIV immunoassays, we incorporated an additional layer that resulted in a seven-layer microfluidic device ( Fig. 26 However, to facilitate the development of HIV immunoassays, we incorporated an additional layer that resulted in a seven-layer microfluidic device ( Fig.…”

“…26 We designed our device with millimeter-sized hydrophilic zones in order to store microgram-quantities of reagents and use microliter-volumes of sample, thereby, minimizing waste and cost (Fig. The wax printing technique produces hydrophobic barriers and hydrophilic channels that define microfluidic network within the threedimensional paper-based device.…”

Paper-based sensors and assays: a success of the engineering design and the convergence of knowledge areas

“…The constructed devices using this method have been exploited for simultaneous detection of BSA and Glc in synthetic urine with colorimetric assays. J. E. Schonhorn et al 171 manufactured other 3D µPAD using a combination of cellulose and nylon-based layers assembled by sheets of adhesive films. The device was composed by six layers with a specific function for the immunoassay: addition of sample and protection for the conjugate layer, storage of conjugate reagent, incubation and reaction of sample with conjugate reagents, capture and visualization of the immunocomplex, wicking of unbound conjugate material away from the back of the capture layer, and wicking of excess sample and washing fluids.…”