Indirect Amperometric Determination of Selected Heavy Metals Based on Horseradish Peroxidase Modified Electrodes

Detection of trace heavy metal ions in water by nanostructured porous Si biosensors

“…This behavior is ascribed to the disrupted function of the HRP, which is induced by Ag + ions binding to the immobilized enzymes, while causing conformational changes. 11,28…”

“…These results are assigned to the non-competitive binding of the Ag + , Pb 2+ and Cu 2+ ions to the enzyme, resulting in conformational changes in its active site, which disrupt and inhibit the HRP specific activity. 11,26,57 The selective behavior of the immobilized HRP is schematically illustrated in Fig. 2a (inset), depicting the specific interaction of certain metal ions ( i.e.…”

“…, Ag + , Pb 2+ and Cu 2+ ) with the enzyme active site while hindering its function. Based on recent studies, 11,28 the enzymatic activity of HRP is also inhibited by other heavy metal ions including, Cd 2+ , Co + , Mn 2+ , Ni + and Hg 2+ ions. To further demonstrate the selectivity of the biosensor towards the different metal ions, we have studied the inhibition of the immobilized HRP by different concentrations of Ag + , Pb 2+ and Cu 2+ ions in the range of 0.6–100 μM.…”

“…9 Traditional quantitative methods for heavy metals analysis include cold vapor atomic absorption spectroscopy, inductively coupled plasma mass spectroscopy, inductively coupled plasma atomic emission spectroscopy, UV-VIS spectroscopy, anodic stripping voltammetry and X-ray absorption spectroscopy. 10–13 These laboratory-based techniques are highly selective and sensitive (as low as part per trillion concentrations), 1,14 but require tedious sample preparation and pre-concentration procedures, involve time-consuming and laborious procedures that can be carried out only by trained professionals, as well as the use of expensive and complex instrumentation. 7,15 In contrast, biosensors have demonstrated a great potential to exceed these limitations in terms of ease of detection, portability, high-throughput analysis of several pollutants and miniaturization toward lab-on-chip technology, while leveraging and even improving sensitivity (10 −9 –10 −20 M) and selectivity.…”

“…1,3,6,25–28 Nomngongo et al have designed an amperometric biosensor for the determination of selected heavy metals based on peroxidase inhibition. 11 The enzyme is immobilized on a platinum–polyaniline electrode, while real water samples are analyzed. The resulting biosensor exhibits a fast response and high sensitivity (limit of detection of 0.091, 0.033 and 0.1 ppb for cadmium, lead and copper, respectively) in correlation with the standard analytical techniques.…”