| Biosensors are portable diagnostic tools used for the rapid detection of pathogens that may require up to 2-7 days to detect otherwise. Biosensors are important in the fields of human and animal diagnostics, bioterrorism preparedness, food and water safety, as well as environmental safety. So a versatile silicon-based biosensor platform for the detection of bacteria that could be used with different biological detecting elements and transducers was fabricated and demonstrated. Silicon (0.01 ohm-cm, p-type) was etched in an electrochemical cell containing hydrofluoric acid solution using anodizing conditions of 5 mA/cm2 for 1 h to fabricate nano-tubular Si (NTS). NTS chips were functionalized into biosensors using biological sensing elements such as enzymes, antibodies and nucleic acids. A chemiluminescence-based enzyme assay was adapted to the biosensor system for the detection of E. coli resulting in a lower detection limit of 102 CFU within 30 min. The NTS-based platform was also functionalized into an optical immunosensor to successfully detect a pure culture of Salmonella Typhimurium within 10 min. Finally, a DNA-based NTS biosensor was developed using an electrochemical transducer for the detection of Salmonella Enteritidis. The NTS DNA biosensor was able to detect S. Enteritidis DNA with a lower limit of detection of 1 pg/mul for PCR-amplified DNA and 10 pg/mu1 for pure culture-extracted DNA. The electrochemical detection process was completed within 60 min. The versatility of the NTS platform for pathogen detection was successfully demonstrated using three different biological sensing elements (enzyme, antibody, and DNA) and two detection methods (optical and electrochemical). Development of commercial biosensing devices using the NTS platform will strengthen biosecurity measures, enable improvement in human and animal health as well as quality assurance in food industry, while also reducing costs associated with loss of productivity, food product recalls and lawsuits. |
