Properties of immobilized enzymes in biosensors

By | 29.10.2017

The biosensor reader device with the associated electronics or signal processors that are primarily responsible for the display of the results in a user-friendly way. The readers are usually custom-designed and manufactured to suit the different working principles of biosensors. Transducers and electronics can be combined, e. The recognition component, often called a bioreceptor, uses biomolecules from organisms or receptors modeled after biological systems to interact with the analyte of interest. This interaction is properties of immobilized enzymes in biosensors by the biotransducer which outputs a measurable signal proportional to the presence of the target analyte in the sample.

The general aim of the design of a biosensor is to enable quick, convenient testing at the point of concern or care where the sample was procured. In a biosensor, the bioreceptor is designed to interact with the specific analyte of interest to produce an effect measurable by the transducer. Binding events result in a physicochemical change that in combination with a tracer, such as a fluorescent molecules, enzymes, or radioisotopes, can generate a signal. There are limitations with using antibodies in sensors: 1. The antibody-antigen interaction is generally irreversible. The use of antibodies as the bio-recognition component of biosensors has several drawbacks. They have high molecular weights and limited stability, contain essential disulfide bonds and are expensive to produce. They are thus especially suitable to create biosensors. Notably, since enzymes are not consumed in reactions, the biosensor can easily be used continuously.

The catalytic activity of enzymes also allows lower limits of detection compared to common binding techniques. However, the sensor’s lifetime is limited by the stability of the enzyme. The sensor principle has the advantage that it does not consume the analyte in a chemical reaction as occurs in enzymatic assays. Biosensors that employ nucleic acid interactions can be referred to as genosensors. If the target nucleic acid sequence is known, complementary sequences can be synthesized, labeled, and then immobilized on the sensor. The favored transduction principle employed in this type of sensor has been optical detection. Photonic biosensors with ultra-sensitivity are nowadays being developed at a research level to easily detect cancerous cells within the patient’s urine. Different research projects aim to develop new portable devices that uses cheap, environmentally friendly, disposable cartridges that require only simple handling with no need of further processing, washing, or manipulation by expert technicians. Organelles form separate compartments inside cells and usually perform function independently.

Different kinds of organelles have various metabolic pathways and contain enzymes to fulfill its function. Commonly used organelles include lysosome, chloroplast and mitochondria. The spatial-temporal distribution pattern of calcium is closed related to ubiquitous signaling what enzymes do the small intestine produce. Mitochondria actively participate in the metabolism of calcium ions to control the function and also modulate the calcium related signaling pathways. Experiments have proved that mitochondria have the ability to respond to high calcium concentration generated in the proximity by opening the calcium channel. In this way, mitochondria can be used to detect the calcium concentration in medium and the detection is very sensitive due to high spatial resolution. Another application of mitochondria is used for detection of water pollution.

Detergent compounds’ toxicity will damage the cell and subcellular structure including mitochondria. The detergents will cause a swelling effect which could be measured by an absorbance change. Experiment data shows application of enzymes in food processing industry change rate is proportional to the detergent concentration, providing a high standard for detection accuracy. Cells are often used in bioreceptors because they are sensitive to surrounding environment and they can respond to all kinds of stimulants.