Amperometric biosensors response measurements

Most of transduction elements used in enzyme-based biosensors are electrochemical amperometric or potentiometric. Typically the enzymes used in amperometric biosensors are oxidases. The main advantages of this class of transducer are the low cost a high degree of reproducibility, and the suitability of many of them for incorporation into disposable electrodes. This type of instrumentation is widely available and can be inexpensive and compact this allows this makes it possible to use them for making on-site measurements. Limitations of amperometric measurements include potential interferences to the response from any electroactive compounds that are present in... 

A Pseudomonas rathonis T-based amperometric biosensor was constructed for the detection of anionic surfactants. Microorganisms contained the plasmid for the degradation of surfactant. The sensor had high sensitivity to DS (the lower limit of DS detection was within the range from 0.25 to 0.75 mg L ) the responses to other detergents— volgonat, decylbenzene sulfonate, metaupon, toluene sulfonate, and alkylbenzene sulfonate—were 82, 36, 20, 10, and 10 % of response to SDS, respectively. As reported, the measurement time did not exceed 5 min. 

Table 3.2 lists the most salient microbial sensors reported to date, together with the type of immobilized microorganism and measurement used, and the response time and dynamic range achieved in each instance. As can be seen, most of these biosensors rely on amperometric measurements. Some of them are described in detail below. 

Immobilization of bioactive material on/in the electrode allows combining bio-reaction selectivity with sensitivity of electrochemical detection. Irrespective of reaction in the biosensor, the electrochemical response is measured, in particular, as current at the given potential (amperometric sensor) or electrode potential (potentiometric sensor). 

More recently, Olivia et al. reported glucose biosensors using Pt nanoparticles deposited boron-doped diamond microfiber (BDDMF) electrode on which GOx was immobilized by overoxidized polypyrrole [140]. Authors reported that amperometric measurement of glucose with the GOx/over-oxidized polypyrrole/Pt-modified BDDMF electrode showed a hnear response in the range of 1-70 mM and was free from ascorbic acid interference. 

---