LECTURE 14 Flashcards
BIOSENSOR
AN ANALYTICAL DEVICE THAT USES A BIOLOGICAL RECOGNITION SYSTEM TO TARGET MOLECULES OR MACROMOLECULES
Biosensors can be coupled to a physiochemical transducer that converts this recognition into a detectable output signal.
Typically biosensors are comprised of three components:
(1) the detector, which identifies the stimulus;
(2) the transducer, which converts this stimulus to a useful output; and
(3) the output system, which involves amplification and display of the output in an appropriate format.
method of biological signalling
Antibody/antigen • Enzymes • Nucleic acids • Cells and viruses • Biomimetic biosensor (artificial or synthetic sensor that mimics the function of a natural biosensor)
Remote Sensing Using an Airborne Biosensor
There is no current method for remote identification of aerosolized bacteria. In particular, such a capability is required to warn of a biological warfare attack prior to human exposure. A fiber optic biosensor, capable of running four simultaneous immunoassays, was integrated with an automated fluidics unit, a cyclone-type air sampler, a radio transceiver, and batteries on a small, remotely piloted airplane capable of carrying a 4.5-kg payload. The biosensor system was able to collect aerosolized bacteria in flight, identify them, and transmit the data to the operator on the ground. The results demonstrate the feasibility of integrating a biosensor into a portable, remotely operated system for environmental analysis.
Lux based biosenseors
Crop yields were reduced with increased application of paper mill sludge to land. A suite of ecotoxicity assays, including, luminescence response of lux-marked bacteria, respirometry and enzyme activity was used to assess toxicity of the paper mill sludge to the soil microbial biomass.
The results from the use of the lux based biosensors correlated well
with more traditional microbial indicators of soil pollution (respiration and enzyme activity).
Allosteric enzymes as biosensors for molecular diagnosis
Allosteric enzymes exhibit a catalytic activity that is modulated by specific effectors, through binding to receptor sites that are distinct from the active site.
Several enzymes, catalyzing easily measurable reactions, have been engineered to allosterically respond to specific ligands, being themselves the main constituent of new-generation biosensors.
Biomagnetic Glasses: Preparation, Characterization, and Biosensor Applications
Approach for the fabrication of biofunctional materials with magnetic capabilities to be used in the design of highly stable, magnetically separable enzyme-based systems was explored. As a model system, immobilization of acetylcholinesterase (AChE) was investigated using biomagnetic glasses composed of a magnetic core with a size tunable porous silica shell. The efficiency of the immobilization was determined by analyzing the biosensing capability of these biomagnetic glasses for the detection of the organophosphorous pesticide paraoxon. Screen printed electrodes with the AChE-biomagnetic glasses showed higher current response and stability than for the free enzyme. The detection limit of the paraoxon biosensor was in the nanomolar range.
Microbial fuel cell biosensor for in situ assessment of microbial activity
Tront et al. (2008). Biosensors and Bioelectronics 24: 586-590
Microbial fuel cell (MFC)-based sensing was explored to provide useful information for the development of an approach to in situ monitoring of substrate concentration and microbial respiration rate. The ability of a MFC to provide meaningful information about in situ microbial respiration and analyte concentration was examined in column systems, where Geobacter sulfurreducens used an external electron acceptor (an electrode) to metabolize acetate. Column systems inoculated with G. sulfurreducens were operated with influent media at varying concentrations of acetate and monitored for current generation.
Thus, the electrical signal produced by the MFC-system provided real-time data for electron donor availability and biological activity. These results have practical implications for development of a biosensor for inexpensive real-time monitoring of in situ bioremediation processes, where MFC technology provides information on the rate and nature of biodegradation processes.
Protein engineering and electrochemical biosensors
The three main strategies in protein engineering for electrochemical biosensor implementation are: rational protein design, directed evolution and de novo protein design.
Each design strategy has limitations to its use in a biosensor format and has advantages and disadvantages with respect to each. The three design techniques are used to modify aspects of stability, sensitivity, selectivity, surface tethering, and signal transduction within the biological environment.
Furthermore with the advent of new nanomaterials the implementation of these design strategies, with the attomolar promise of nanostructures, imparts important generational leaps in research for biosensor construction, based on highly specific, very robust, and electrically wired protein engineered biosensors.
Biosensors as useful tools for environmental analysis and monitoring
Recent advances in the development and application of biosensors for environmental analysis and monitoring are reviewed in this article. Several examples of biosensors developed for relevant environmental pollutants and parameters are briefly overviewed. Special attention is paid to the application of biosensors to real environmental samples, taking into consideration aspects such as sample pretreatment, matrix effects and validation of biosensor measurements. Current trends in biosensor development are also considered and commented on in this work. In this context, nanotechnology, miniaturisation, multi-sensor array development and, especially, biotechnology arise as fast-growing areas that will have a marked influence on the development of new biosensing strategies in the near future.
Biochemical oxygen demand (BOD)
DNA biosensor technology, Biochemical oxygen demand (BOD) is an important index for monitoring organic pollutants in water.
The conventional standard method (5-day BOD test, BOD5), however, is a complicated and time-consuming procedure, including a 5-day incubation, and also requires considerable experience and skill to get reproducible results.
To overcome these problems, microbial biosensors allowing the rapid estimation of BOD have been developed.
Biosensors for pharmaceuticals and emerging contaminants based
on novel micro and nanotechnology approaches
Adrián et al (2009). Biosensors for Environmental Monitoring of Aquatic Systems The Handbook of Environmental Chemistry, 2009, Volume 5J, 47-68
The investigation of new sensing principles and technologies for the detection of molecular binding events has created great expectations on numerous major industrial sectors, such as healthcare, food, water and agriculture.
Combining many of these advances with the potential of the immunochemical systems has allowed developing novel biosensors that provide interesting advantages against the traditional strategies for analysis, such as the possibility of multianalysis, development of field analytical methods and fabrication of easy end-user devices.
Specifically, many efforts have been lately invested to control residues of pharmaceuticals in food and environmental samples, as an indication of the impact of the human activity in the media. Human and veterinary drugs, such as antibiotics, hormones, analgesics, cytostatics or β-blockers, show a high potential risk of negative effects in the environment and public health.
Environmental biosensors for organochlorines, cyanobacterial toxins and endocrine disrupting chemicals
Environmental biosensors and related techniques for monitoring organochlorines, endocrine disrupting chemicals and cyanobacterial toxins are described. The practical requirements for an ideal environmental biosensor are analyzed. Specific case studies for environmental applications are reported for triazines chlorinated phenols, PCBs, microcystins, and endocrine disrupting chemicals. A new promising approach is reported for microcystins and alkylphenols that utilize electrooptical detection.
Influence of seasonal environmental variables on the distribution of presumptive fecal coliforms around an Antarctic research station
These findings highlight the need for year-round monitoring of fecal coliform distribution in Antarctic waters near research stations to produce realistic evaluations of sewage pollution persistence and dispersal.
Wireless, Remote-Query, and High Sensitivity Escherichia coli O157:H7 Biosensor Based on the Recognition Action of Concanavalin A
Escherichia coli O157:H7 is detected using a remote-query (wireless, passive) magnetoelastic sensor platform to which a 1 μm thick layer of Bayhydrol 110 and then a layer of functionalized mannose is applied. The multivalent binding of lectin concanavalin A (Con A) to the E. coli surface O-antigen and mannose favors the strong adhesion of E. coli to the mannose-modified magnetoelastic sensor; E. coli is rigidly and strongly attached on the mannose-modified sensor through Con A, which works as a bridge to bind E. coli to the mannose-modified sensor surface. As E. coli is bound to the sensor, its resonance frequency shifts, enabling quantification of E. coli concentration with a limit of detection of 60 cells/mL and a linear logarithmic response range of 6.0 × 101 to 6.1 × 109 cells/mL. The analysis can be directly conducted without incubation and completed in 3 h or less.
