Ion Selective Amperometric Biosensors for Environmental Analysis of Nitrate, Nitrite and Sulfate

Abstract

Inorganic ions that can be redox-transformed by living cells can be sensed by biosensors, where the redox transformation gives rise to a current in a measuring circuit. Such biosensors may be based on enzymes, or they may be based on application of whole cells. In this review focus will be on biosensors for the environmentally important ions NO3−, NO2−, and SO42−, and for comparison alternative sensor-based detection will also be mentioned. The developed biosensors are generally characterized by a high degree of specificity, but unfortunately also by relatively short lifetimes. There are several investigations where biosensor measurement of NO3− and NO2− have given new insight into the functioning of nitrogen transformations in man-made and natural environments such as sediments and biofilms, but the biosensors have not become routine tools. Future modifications resulting in better long-term stability may enable such general use.

Functional Expression of a Mo–Cu-Dependent Carbon Monoxide Dehydrogenase (CODH) and Its Use as a Dissolved CO Bio-microsensor

“…The mechanism is similar to bio-microsensors which successfully developed and operated before, where NO 3 – or NO 2 – is converted to N 2 O by bacteria, or urea to CO 2 18 by urease enzyme which is then detected by Clark-type N 2 O or CO 2 transducers, respectively. They also exhibited linear responses to the analyte when the ions or molecules were transformed to gas before reaching the transducer …”

“…They also exhibited linear responses to the analyte when the ions or molecules were transformed to gas before reaching the transducer. 17 Several parameters play important roles in determining the performance of this Clark-type enzyme-based microsensor. The activity of the enzyme, the length of the reaction chamber filled with enzyme that catalyzed oxidation/reduction reactions, the use/concentration of enzyme cofactors, and the enzyme oxidant all contribute to the sensor's response, sensitivity, and stability during operation.…”

“…The major drawback associated with the use of an enzymemodified electrode surface is fouling of the electrode surface by the sample constituents (bacteria, proteins, or organic molecules) 17 and enzyme leaching, 18 which may contribute to shifts in the baseline signal and the rapid loss of sensor activity. 19 Hence, for long-term monitoring, the sensor's catalyst (and analyte recognition element) is preferably shielded in a compartment with a membrane capable of excluding the fouling species and preventing enzyme leaching.…”

An Improved Algorithm for Measuring Nitrate Concentrations in Seawater Based on Deep-Ultraviolet Spectrophotometry: A Case Study of the Aoshan Bay Seawater and Western Pacific Seawater

“…This technology integrates the sample preparation, reaction, separation, detection, and other basic operation units of biological and chemical processes into a micro-scale chip, and automatically completes the whole process of analysis. This is suitable for the trace detection of nitrate in seawater, and is advantageous due to its low power consumption, high sensitivity, and fast speed [26][27][28][29]. However, the working time of wet chemical analysis depends on the stability and consumption rate of chemical reagents and it is hard to realize long-term (more than three months) in-situ monitoring.…”

A sensitive electrochemical sensor based on metal cobalt wrapped conducting polymer polypyrrole nanocone arrays for the assay of nitrite

“…If excessive intake of nitrite, it will cause hemoglobin to oxidize, leading to tissue hypoxia, and under certain conditions, carcinogens-nitrosamines can be obtained [5,6]. In recent years, numerous analytical techniques have been used to determine nitrite, such as high-performance liquid chromatography, electrochemical methods, spectrophotometry, and Raman spectroscopy [7][8][9][10][11]. Among them, electrochemical techniques have been widely and continuously researched for monitoring nitrite owing to the rapid response, ease in sample preparation and analysis, high cost-effectiveness [12][13][14][15].…”