Biosensors made entirely of paper are becoming increasingly popular
due to their low cost, facile fabrication, and lightweight portability
for in-field measurements. However, it is difficult to store nanoparticles
in paper substrates without irreversibly binding them to the cellulose
matrix. This makes it challenging to fabricate biosensors incorporating
nanoparticle probes in paper-based reservoirs. Here, we overcome this
limitation with a new method for storing protein-decorated nanoparticles
on paper substrates that also allows to release them on demand. It
consists of spotting nanoparticles onto pieces of filter paper previously
modified with polystyrene sulfonate. Gold nanoparticles modified with
avidin or antibodies can be easily transferred from the dry reservoir
to a receiving wet piece of paper by simply pressing with the finger
or a clamp. Paper-based immunosensors incorporating the reservoir
enabled the detection of glycoprotein B from human cytomegalovirus
in serum with a limit of detection of 0.03 ng mL–1 and a total assay time of only 12 min. The low limit of detection
obtained with a short assay time along with the long shelf-life of
the reservoirs make the proposed paper-only biosensors ideal of point-of-care
diagnostics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.