A low-fouling and reusable biosensor for the sensitive electrochemical assay of tuberculosis gene

Abstract

A low-cost, portable, and reusable biosensor for the rapid and selective quantitation of tuberculosis (TB) gene with low expression levels in early-stage serum specimens is highly desirable but remains a challenge. Herein, a novel biosensor was fabricated using the layer-by-layer assembly of gold nanoparticles (Au NPs), polyethylenimine (PEI) and chondroitin sulfate (CS). The synergistic effect of PEI and CS endows this biosensor antifouling properties towards single proteins, even towards complex biological systems. Before and after the incubation in 10% serum, only 6.4% peak current change of DPV response was obtained. To the best of our knowledge, a few examples have been reported on the successful application of CS in mitigating biofouling. Next, a special gene only representing TB was modified on CS-modified electrode, and this biosensor showed a fast response with good linear concentration dependence on the target DNA in the range 10−14 M to 10−10 M. More importantly, this biosensor based on the reversible bonding of DNA double strand could be reused for at least four times after the regeneration of urea without any passivation, which further reduced the cost of the entire strategy. To some extent, this indicates that the CS-modified biosensor has certain practical application prospect and can be extended to fabricate similar biosensors for the detection of other diseases.