Poly(methyl methacrylate)-Based Nanofluidic Device for Rapid and Multiplexed Serological Antibody Detection of SARS-CoV-2

Abstract

The outbreak of SARS-CoV-2 has emphasized the value of point-of-care diagnostics, as well as reliable and cost-effective serological antibody tests, to monitor the viral spread and contain pandemics and endemics. Here, we present a three-dimensional (3D) nanofluidic device for rapid and multiplexed detection of viral antibodies. The device is made from poly­(methyl methacrylate) and contains 3D fluidic channels with nanoscale topography variations on the millimeter length scale, enabled by combining gray-scale e-beam lithography and nanoimprint lithography. It works with capillary pumps only and does not require a complex microfluidic setup and pumps, which hinder the widespread usage of micro- and nanofluidic devices. The device is designed to size dependently immobilize particles from a multiparticle mixture at predefined positions in nanochannels, resulting in distinct trapping lines. We show that it can be used as an on-chip fluorescence-linked immunosorbent assay for highly specific and sensitive multiplexed detection of serological antibodies against different viral proteins. Further test flexibility is demonstrated by on-bead color multiplexing for simultaneous detection of IgG and IgM antibodies in convalescent human serum. The particle sorting is further leveraged to enable concurrent detection of anti-spike (SARS-CoV-2) and anti-hemagglutinin (influenza A) antibodies. The device’s applications can be further extended to detect a large variety of diseases simultaneously in a reliable and straightforward manner.

Injection Molding of Thermoplastics for Low-Cost Nanofluidic Devices

“…The low-cost characteristic of the presented fabrication route comes from the high-volume throughput of injection molding. This is needed as one of the potential applications of the device is in point-of-care diagnostics, as demonstrated in our previous work . Moreover, due to the nanoscale height in combination with an extremely low aspect ratio, thermoplastic materials are favored due to their higher mechanical stability in comparison to soft lithography materials, such as PDMS.…”

“…Moreover, due to the nanoscale height in combination with an extremely low aspect ratio, thermoplastic materials are favored due to their higher mechanical stability in comparison to soft lithography materials, such as PDMS. A more elaborate overview of different fabrication methods for microfluidic device fabrication and their associated strengths and weaknesses, can be found in the work of Scott et al and Gale et al The presented injection-molded devices can potentially be used to perform on-chip immunoassays in similarity to thermoplastic devices fabricated through nanoimprint lithography …”

“…Second, its completely passive operation means that it does not require a cumbersome integration of inlet and outlet connectors. The presented devices can be used in a wide range of applications, from on-chip bead-based immunoassays for antibody or biomarker detection to single-cell analysis and optical particle size determination …”

Microfluidics: a concise review of the history, principles, design, applications, and future outlook

“…Mortelmans et al 139 fabricated a 3D nanofluidic device using a combination of gray-scale e-beam lithography and nanoimprint lithography for rapid and multiplexed detection of viral antibodies.…”

Rapidly Adaptable Multiplexed Yeast Surface Display Serological Assay for Immune Escape Screening of SARS-CoV-2 Variants

“…Micro- and nanofluidic approaches can potentially provide sensitive and specific testing at a low cost. These miniaturized assays typically use microliter sample volumes and are adaptable for multi-antigen-testing for detecting SARS-CoV-2 and influenza A antibodies in parallel 18 , as well as performing antibody affinity profiling and assessing antibody titers 19 . Miniaturized serology tests have also been built using point-of-care diabetic glucometers 14 .…”