A miniaturized bismuth-based sensor to evaluate the marine organism Styela plicata bioremediation capacity toward heavy metal polluted seawater

Abstract

Cadmium and lead are highly toxic heavy metals which cause a severe worldwide pollution. In addition to the toxic effect produced by the direct exposure, they can be bioconcentrated and accumulated in living organisms, including humans. Herein, a miniaturized and disposable electrochemical sensor was improved for the simultaneous detection of cadmium and lead ions to study the bioremediation of polluted seawater in presence of the filter-feeding marine organism Styela plicata. A screen-printed electrode modified in situ with a bismuth film was selected using the anodic stripping analysis as detection technique. This sensor was coupled with a portable potentiostat and the detection of cadmium and lead ions was carried out by Square Wave Anodic Stripping Voltammetry, allowing the simultaneous detection of both heavy metals at ppb level (LOD=0.3ppb for lead, 1.5ppb for cadmium). This analytical tool was then applied to assess the bioremediation capacity of S. plicata through a bioremediation experiment, in which the organism has been exposed to seawater artificially polluted with 1000ppb of Cd and Pb. The matrix effect of both seawater and acid digested biological samples was evaluated. A bioconcentration phenomenon was observed for both heavy metals through the analysis of S. plicata tissues. In details, Pb resulted to be about 2.5 times more bioconcentrated than Cd, giving an effective bioremediation level in seawater of 13% and 40% for Cd and Pb, respectively. Thus, our results demonstrate the capability of S. plicata to bioremediate Cd and Pb polluted seawater as well as the suitability of the electrochemical sensor for contaminated marine environment monitoring and bioremediation evaluation.

Effects of Humidity, Temperature and Bismuth Electrodeposition on Electroanalytical Performances of Nafion‐coated Printed Electrodes for Cd2+ and Pb2+ Detection

“…SPEs were successively treated by using the procedure reported in our previous paper [38]. Briefly, the sensor was covered by a drop of acetate buffer 50 mM + 50 mM NaCl at pH 4.6, and pre-treated by applying an oxidative potential of 1.6 V for 300 s. Subsequently, the sensor was rinsed with double-distilled water and dried at room temperature.…”

“…Each Bi-NCSPEs were obtained by in situ electroplating in the working solution, composed of 5 mL of acetate buffer 50 mM + NaCl 50 mM at pH 4.6 containing 0.5 ppm of Bi 3 + . The Bi 3 + concentration and the working solution characteristics were chosen based on investigations reported in previous studies [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]38].…”

Screen-Printed Electrodes Modified with “Green” Metals for Electrochemical Stripping Analysis of Toxic Elements

“…The vast majority of applications of electroplated Bi SPEs involve the determination of Pb, Cd, and Zn by ASV [ 16 , 17 , 19 , 26 ] but there are also selected applications of stripping analysis after adsorptive accumulation using ex situ plated BiFEs; examples of recent relevant work include the determination of Sb(III) with quercetin-5′-sulfonic acid as the chelating agent [ 69 ] and of platinum group metals (Pt, Pd, Rh) with dimethylglyoxime as the ligand [ 70 ]. Other recent notable applications include methodologies for the determination of the size and particle concentration of Cd-based quantum dots (QDs) [ 71 ], a hybrid stripping fluorescence method to detect Cd in water [ 72 ], a study of heavy metal complexation [ 73 ], and phytoremediation studies [ 74 , 75 ].…”

Analysis of Toxic Heavy Metal Content of the Most Widely Consumed Fruits

“…26 Among heavy metals, cadmium (Cd) and lead (Pb) are non-essential elements with well-known toxic effects on humans. 27 Fruit water (juice) is a good source of antioxidants and inhibits the production of high ROS, while heavy metals initiate the production of such species. It could be concluded that high content of heavy metals may reduce the antioxidant property of fruits.…”