Bio Sensors
A biosensor is a device use to detect a specific component; it reads the biological reaction with a physicochemical detector component
There are 3 parts in biosensor:
- Biological reaction (receptors, protein, antibodies, nucleic acids)
- Detection element (transforms the signal resulting from the interaction of the sample with the biological element into another signal)
- Electronic component which coverts collected info into user-friendly information for easy analysis
They are generally 2 kinds of biosensors: Specific or Non-specific
An example of non-specific biosensors, as bacteria A are expose to increasing amount of toxic, the metabolism activity of the cell will decrease, reduce in a reduced signal output. The signal output can be used to find the concentration of toxic.
Specific biosensors are genetically engineered, inputting specific promoter and reporter gene. The sensitivity and limit of detection can be alter by the change of promoter and reporter component.
Ways of detection by biosensors:
1. Electrochemical (measures enzyme reaction)
2. Piezoelectric
3. Photometric
An example of a mercury biosensor
A fully constructed whole bacteria cell biosensor is already known in the market. It has a gene fusion of PmerTPADluxCDBAE. To make it simpler, we need to break down the bacteria to simple component. This strain of bacteria is a genetic modified biosensor, which means it is a specific biosensor. Basically LuxCDBAE gene are extracted from Vibrio fischeri and are fused to a inducible merTPAD gene(mercury resistance). The Gene fusion is than input into Escherichia coli (CM2624). The resulting specific biosensor will be able to emit light in the presence of mercury ions.
Pros and Cons of using biosensors
Before using Biosensors as your way to detect pollutant, first we need to know the pros and cons of the detection method. This is to make sure it can be suitable for the context of your research and give a better accuracy and efficiency of testing the concentration of “mercury”
| Pros | Cons |
| Real time measurement (E.g. soil test, it test exactly % of soil and parts of soil affected) | Inhibiting of biosensors due to multiple toxic component (E.g. interferences of Lead) |
| Very effective in monitoring effect of bio remediation | Characteristic of biosensor and indigenous organism different , thus it may be difficult to reflect the real impact of mercury on the location |
| Test the bio availability. To calculate the concentration of the mercury which can be uptake by organism, rather than the total mercury found in the medium | Expensive and labor intensive to invent |
| Able to adjust the sensitivity of biosensor, by changing the reporter gene being used. With lux currently the most sensitive reporter, followed by lacZ than gfp. |
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| Able to collate the psychological status and response of microbes so as to calculate the real effect done by the mercury pollution |
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| Flexibility of choice of host strain, results can be extrapolated to compare effects on organisms, if bioengineering technologies improves this may be able to collate to effect of animals and ultimately human |
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Biosensors VS Conventional chemical method
The points listed below are for you to compare and decide on which technology suits the criteria of the company most. Capital constrain, Professional worker and environmental impacts are some points to consider.
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| Biosensors | Conventional Chemical method |
| Cost of equipment | Cheap | Expensive |
| Time | Fast | Slow |
| Adaptability | Cannot be used for all condition ( E.g. temperature difference) | Can be used |
| Initial cost | High due to the research need to fully understand the microbes | Fixed price |
| Diversity of measurment | Specific detection, need a combination of microbes | Can measure all |
| Environment impact | Almost perfectly environmental friendly | Feedstock for the chemical process are not environmental friendly |