Universal DNA detection realized by peptide based carbon nanotube biosensors
Although DNA recognition has been achieved in numerous biosensors by various sensing probes, the utilization of bio-interaction between DNA and biomolecules was seldom reported in the universal DNA detection. Peptide as a natural molecule owns the unique property to grasp universal DNAs while it has excellent selectivity for DNAs after being functionized with specific groups. In this work, we report a natural peptide based carbon nanotube (CNT) thin-film-trasistor (TFT) biosensor, which can achieve sensitive sequence-independent DNA detection. In the presence of DNA, a significant increase of ΔIon could be observed within 5 minutes, which was analyzed to the electrostatic adsorption between the opposite Zeta potential of DNA and peptide. With the gradual increase of concentration, the ΔIon signals agrees with the Hill-Langmuir model (R2 = 0.98), indicating a negatively cooperative interaction between peptide and DNA (the Hill coefficient n<1). Compared with the former reported universal DNA bio-detector and nanodrop (a spectrometer from Thermo scientific™), this unique peptide based CNT-DNA sensor demonstrated a broader sensing range from nearly 1.6×10-4 to 5 μmol/L and much lower detection limit of approximately 0.88 μg/L. In the quantification of cDNA from T47D cancer cells, this unique peptide based CNT sensor could achieve efficient cDNA detection. To the best of our knowledge,this is the first report on the utilization of natural peptide as sensing element in the design of CNT based DNA biosensors, which enables highly efficient universal DNA detection.