doi:10.1038/nindia.2015.80 Published online 16 June 2015
Researchers have fabricated a simple, low-cost paper sensor that can detect minute traces of carcinoembryonic antigen, a tumour marker often present in serum samples from cancer patients1. This paper-based sensor is thus potentially useful for diagnosing colon, lung, ovarian and breast cancers, which all produce carcinoembryonic antigen.
The researchers synthesized the paper sensor by dipping filter paper into a solution of polymer poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) and reduced graphene oxide. They then treated the polymer- and graphene-coated paper with ethylene glycol solution and dried it.
To explore the sensor’s ability to detect carcinoembryonic antigen, the scientists smeared antibodies specific to the antigen on the paper electrode. They then dipped the antibody-coated electrode into a phosphate-buffered saline solution. The researchers found that the current decreased with increasing antigen concentration up to a concentration of 10 nanograms per millilitre. They attributed this observed decrease in current to the formation of antigen–antibody complexes, which diminished charge transfer on the electrode surface.
In addition, the paper electrode selectively detected the cancer antigen in the presence of other disease biomarkers.
The researchers say that the paper sensor exhibited only low conductivity losses after repeated cycles of folding and unfolding.
1. Kumar, S. et al. Reduced graphene oxide modified smart conducting paper for cancer biosensor. Biosens. Bioelectron. 73, 114–122 (2015)