RESUMO
We herein describe the development of a single-walled carbon nanotube (SWNT)-based electrical biosensor consisting of a two-terminal resistor, and report its use for the specific, label-free detection of pathogenic bacteria via changes in conductance. The ability of this biosensor to recognize different pathogenic bacteria was analyzed, and conditions were optimized with different probe concentrations. Using this system, the reference strains and clinical isolates of Staphylococcus aureus and Escherichia coli were successfully detected; in both cases, the sensor showed a detection limit of 10 CFU. This SWNT-based electrical biosensor will prove useful for the development of highly sensitive and specific handheld pathogen detectors.
Assuntos
Técnicas Biossensoriais/métodos , Escherichia coli/isolamento & purificação , Nanotubos de Carbono/química , Staphylococcus aureus/isolamento & purificação , Sequência de Bases , Sondas de DNA/química , Sondas de DNA/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Eletroquímica , Escherichia coli/genética , Humanos , Limite de Detecção , Staphylococcus aureus/genéticaRESUMO
We investigate the effect of functional groups of pyrene molecules on the electrical sensing performance of single-walled carbon nanotubes (SWNTs) based DNA biosensor, in which pyrenes with three different functional groups of carboxylic acid (Py-COOH), aldehyde (Py-CHO) and amine (Py-NH2) are used as linker molecules to immobilize DNA on the SWNT films. UV/Visible absorption spectra results show that all of the pyrene molecules are successfully immobilized on the SWNT surface via pi-pi stacking interaction. Based on fluorescence analysis, we show that the amide bonding of amine terminated DNA via pyrene containing carboxylic groups is the most efficient to immobilize DNA on the nanotube film. The electrical detection results show that the conductance of Py-COOH modified SWNT film is increased upon DNA immobilization, followed by further increase after hybridization of target DNAs. It indicates that the pyrene molecules with carboxylic acid groups play an important role to achieve highly efficient label-free detection by nondestructive and specific immobilization of DNAs.