Silicon-based microelectronics represents the platform of our modern information technology. In recent years, silicon technology has been utilized to couple data processing systems to chemical and biological structures, integrating ion-selective materials and simple biomolecules or even cells and cell systems. The main advantage of these (bio-)chemical sensors is the high sensitivity and selectivity of their chemical and biological component as well as the possibility of miniaturization down to the nanometer scale. (Bio-)chemical sensors have been developed as rugged and reliable devices for the rapid and quantitative detection of specific analytes. For example, enzymes allow to monitor the blood glucose concentration of diabetic patients, a pH electrode may adjust the proper fermentation routine for cheese
production and sensors and catalysts control the car pollution. (Bio-)chemical sensors constitute an interdisciplinary interface between the environment and data processing systems. Moreover, because these sensors can be designed in a modular concept, the combination of single sensors to sensor arrays is possible. We present some examples of new silicon-based (bio-) chemical sensors, which have been developed in a collaboration between ISG (FZJ) and the University of Applied Sciences Aachen (Jülich division): • capacitive field-effect sensors as a combination of ionophores or enzymes and silicon technology, • a silicon-based multi-parameter hybrid ion-sensitive FET (ISFET) module suitable for sensor arrays, • a beetle/chip biologically sensitive field-effect transistor (BioFET) as a first step towards a bioelectronic device with extraordinary sensory abilities. All described (bio-)chemical sensors utilize the field effect to transfer the detected (bio-) hemical information to an electrical signal.
Monday, September 1, 2008
Bioelectronic DNA detection involves forming an electronic circuit mediated by nucleic acid hybridization and it serves as the basis for a DNA detection system called eSensor™ [1-4]. This system uses low-density DNA chips containing electrodes coated with DNA capture probes. Target DNA present in the sample hybridizes specifically both to capture probes and ferrocene labeled signal probes in solution thereby generating an electric current. Currente Sensor DNA chips contain as many as 36 electrodes for simultaneous detection of multiple pathogens from a single sample.
Many pathogens cause both acute and chronic disease at relatively low copy number and may be difficult or impossible to propagate in culture. Thus, most pathogen detection systems rely on nucleic acid amplification by using polymerase chain reaction (PCR). One highly effective amplification strategy targets conserved sequences among the family of organisms of interest. Such broad-range PCR strategies have been used to identify and characterize several known and previously uncharacterized bacteria [5,6] and viruses [7,8]. In order to maximize the utility of these effective pathogen nucleic acid amplification systems, amplification needs to be coupled with rapid, sensitive, and specific detection. Bioelectronic DNA detection by use of the eSensor chip might fulfill this need.
Human papillomaviruses (HPV) serve as an ideal model system for determining the efficiency and feasibility of eSensor DNA detection technology since there are at least 30 distinct genital HPV types that can be effectively amplified with broad-range consensus PCR primers. We designed two eSensor chips, each containing 14 probes specific for the conserved L1 region of the HPV genome. We evaluated clinical cervical cytology samples known to contain one or more HPV types. The eSensor DNA detection platform successfully detected the correct HPV type in most of these clinical samples, demonstrating that the system provides a rapid, sensitive, specific, and economical approach for multiple-pathogen detection and identification from a single sample.Background We used human papillomaviruses (HPV) as a model system to evaluate the utility of a nucleic acid, hybridization-based bioelectronic DNA detection platform (eSensor) in identifying multiple pathogens.