A multipurpose biocapture nanoplatform based on multiwalled-carbon nanotubes non-covalently functionalized with avidin: Analytical applications for the non-amplified and label-free impedimetric quantification of BRCA1

Abstract

We introduce an innovative and versatile multipurpose biocapture nanoplatform made of multi-walled carbon nanotubes (MWCNTs) non-covalently functionalized with avidin (Av) as support to immobilize a biorecognition element just by mixing them in solution. As proof-of-concept of the advantages of this platform, we propose a non-amplified and label-free impedimetric BRCA1 biosensor prepared by immobilization of a biotinylated DNA probe (bDNAp) at MWCNTs-Av nanoplatform and further deposition of the resulting biosensing layer at glassy carbon (GCE) or screen printed carbon (SPCE) electrodes. The hybridization event was detected from the changes in the charge transfer resistance (Rct) of [Fe(CN)6]3-/4-. The resulting genosensor made possible the fast, highly sensitive and selective quantification of BRCA1 in a simple way, with a linear range between 1.0 fM and 10 nM, a sensitivity of (460 ± 9) ΩM−1 (r2 = 0.997), a detection limit of 330 aM and a quantification limit of 1.0 fM. The reproducibility was 5.2% and 4.6% for 1.0 × 10−12 M and 1.0 × 10−14 M BRCA1, respectively, using the same MWCNTs-Av-bDNAp platform, and 5.2% for 1.0 × 10−12 M BRCA1 using 5 different platforms. The biosensor was challenged with fully non-complementary and mismatch DNA sequences, and mixtures of them, without interference. The detection of BRCA1 in enriched diluted human serum samples showed excellent recovery percentages.