RSC Adv., 2018, 8, 19754–

Applied Surface Science Advances

The ecosystem delivers natural services to humans and other living beings that are crucial for health, quality of life and existence. The purpose of environmental monitoring is to realize whether the quality of the environment is getting better or worse. Different types of techniques are used for environmental monitoring. Traditional methods are mostly time-consuming, involve expensive equipment and skilled personnel. Biosensors represent an exciting and pertinent approach to overcome the limitations of existing devices used in the diverse areas of environmental monitoring. It can complement laboratory-based techniques and can also be applied for remote testing. Electrochemical nucleic acid (NA) biosensor integrates the sensitivity of electroanalytical methods with the inherent bio-selectivity of NA. The acceptance of NA biosensors depends on specificity, sensitivity, small molecule detection as well as cost-effectiveness. Considering these factors, a huge number of nanomaterials have been employed to facilitate immobilization of NA as well as to enhance conductivity and sensitivity. The NA component in the biosensor detects the analyte(s) based on signal generation owing to binding or catalytic event, which is proportional to the concentration of the analyte(s). This review compiled the components and strategies of building electrochemical NA biosensors, methods of transducing NA, the process of enhancing conductivity with nanomaterials and recent progress and innovative tactics used in the field. Besides these, applications of electrochemical NA biosensors for qualitative and quantitative analysis of environmental pollutants, steroid compounds, mycotoxins, heavy metals, antibiotic residues and pesticides have been discussed with illustrations along with limitations, challenges, future directions for the electrochemical NA biosensor applications and development.

2004

The work presented in this thesis was concerned with the development of single-use drop-on sensors incorporating a three-electrode configuration (graphite carbonworking electrode, carbon-counter electrode and silver/silver chloride -reference electrode) for on-site detection of toxic heavy metals in various environmental matrices. The fabricated three-electrode configuration system was coupled with square-wave anodic stripping voltammetry (SWASV) or constant current stripping chronopotentiometry (CCSCP) in order to provide a means of a relatively inexpensive on-site detector for trace levels of lead (II), copper (II) and cadmium (II). Detections and determinations of these metals were carried out on bare screen-printed carbon electrodes (SPCEs), mercury film SPCE, bismuth film SPCE and SPCEs modified with Nafion, 2,5-Dimercapto-1, 3, 4-thiadiazole (DMTD), bismuth oxide (E^Os) and polyethyleneimine (PEI) using the optimised procedures developed for measurements. With the optimised working conditions, the results obtained indicate that the screen-printed electrochemical sensors are sensitive and reproducible enough for the CCSCP and SWASV determination of lead, copper and cadmium in the microgram per litre -milligram per litre range. Limits of detection below 20 jag I"1 were estimated for the trace metal detection of lead, copper and cadmium on both the bismuth and mercury film electrodes. For the bare SPCE, detection limits of 35, 45 and 59 pig I'1 were obtained for lead, cadmium and copper detection using CCSCP. The reproducibility of the measurements, which also contributed to the interest in developing the electrochemical sensing devices for metal ions, was below 15 % for the bare SPCE, bismuth film SPCE, and mercury film SPCE. Modifications of SPCEs with an ion-exchanger (Nafion) and a complexing agent (DMTD) provided means of increasing the sensitivity of stripping response obtained at the bare SPCE. Detection limits of 20 and 22 pg I"1 were estimated for lead (II) measurements at the Nafion modified SPCE and at the screen-printed DMTD modified electrode, respectively. • Dr. D. W.M. Anigan for his continued scientific support. • Prof. M. Valiente (UAB, Barcelona, Spain) and Tecnicas de Protection Ambiental S.A. (TPA, Madrid, Spain) for providing the samples and analytical data used as part of the studies. • My colleagues (Greg, Belen, Nizal) at the Cranfield Biotechnology Centre as well as others at IB ST, Silsoe. • The European Union for funding the DIMDESMOTOM project on the development of improved sensitive and robust sensing devices capable of real time and on-site detection analysis of toxic heavy metal in various environmental matrices. • Family and friends for their patience and understanding. • To almighty God for his mercy, protection and guidance.

RSC Advances

A new Schiff base named 1,1′-(-(naphthalene-2,3-diylbis(azanylylidene))bis(methanylylidene))bis(naphthalen-2-ol) (NDNA) was synthesized by condensation reaction and then characterized by spectroscopic techniques for structure elucidation.

The presence of heavy metal in food chains due to the rapid industrialization poses a serious threat on the environment. Therefore, detection and monitoring of heavy metals contamination are gaining more attention nowadays. However, the current analytical methods (based on spectroscopy) for the detection of heavy metal contamination are often very expensive, tedious and can only be handled by trained personnel. DNA biosensors, which are based on electrochemical transduction, is a sensitive but inexpensive method of detection. The principles, sensitivity, selectivity and challenges of electrochemical biosensors are discussed in this review. This review also highlights the major advances of DNA-based electrochemical biosensors for the detection of heavy metal ions such as Hg 2+ , Ag + , Cu 2+ and Pb 2+ .

Microporous and Mesoporous Materials, 2016

In this work, glutathione was grafted on mesoporous silica materials by silanization with (3mercaptopropyl)trimethoxysilane, subsequent reaction with 2,2 0-dipyridyldisulphide and a final treatment with glutathione. The obtained glutathione-functionalized materials have been characterized by powder X-ray diffraction, FT-IR, scanning electron microscopy, transmission electron microscopy, nitrogen gas sorption and X-ray fluorescence. In addition, the hybrid materials were used in the preparation of modified carbon paste electrodes MCPE by mixing quantities of glutathione-containing materials with paraffin oil and graphite for Cd(II) detection in aqueous media by square wave adsorptive stripping voltammetry. Two materials were used for the preparation of MCPE, (A) the first material was obtained by the grafting of glutathione on the pyridyldisulphide pending ligand of the mesoporous material, (B) the second one, was obtained by grafting a cadmium-glutathione complex on the pyridyldisulphide pending ligand of the mesoporous material. For the latter, elimination of cadmium ions was carried out by treatment with HCl 2 M for 2 h and wash with MilliQ water before preparing the MCPE. To achieve the most accurate and sensitive Cd(II) electrochemical measurements, optimization of the operating parameters in pre concentration and detection steps was performed. The responses are pH dependent, being the optimal conditions 120 s of electrolysis time in buffer solution (pH 6.4). The voltammetric responses increase linearly with the pre concentration time and with metal ion concentrations ranging from 1 to 100 ppb. The metal detection limits were 2 and 4 ppb for materials (A) and (B), respectively, after 5 min pre concentration time.

Pure and Applied Chemistry, 2010

An electrochemical nucleic acid (NA)-based biosensor is a biosensor that integrates a nucleic acid as the biological recognition element and an electrode as the electrochemical signal transducer. The present report provides concepts, terms, and methodology related to biorecognition elements, detection principles, type of interactions to be addressed, and construction and performance of electrochemical NA biosensors, including their critical evaluation, which should be valuable for a wide audience, from academic, biomedical, environmental, and food-testing, drug-developing, etc. laboratories to sensor producers.

Biosensors and Bioelectronics, 2017

A review on various electrochemical techniques for heavy metal ions detection with different sensing platforms, Biosensors and Bioelectronic,

2019

Electrochemical sensors and biosensors combine the sensitivity of electroanalytical methods with the selectivity of a sensor or biosensor surface. The chemical or biochemical component (receptor) i ...

Chemical Engineering Journal , 2018

A new electrochemical sensor for the selective detection of Cd 2+ ion based on Schi ff base, 1,1 ′ -(biphenyl-4,4 ′ -diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene) dinaphthalen-2-ol (BZNA) having from both moieties 2-hydroxy-1-iminomethylnaphthalene and benzidine core is presented. BZNA was synthesized by condensationreaction and then fully characterized. A thin 󿬁 lm of BZNA was fabricated onto Na 󿬁 on/Glassy carbon electrode(GCE) with 5.0% ethanolic solution of Na 󿬁 on as the conducting coating agent. A slurry of BZNA was used to coatthe GCE (GCE; 0.0316cm 2 ) as a thin layer for the selective detection of Cd 2+ ion in an aqueous solution. A linearcalibration curve that has a linear dynamic range (LDR) from 0.1nM to ∼ 0.1mM is obtained. From the slope of the plot, the calculated sensitivity, limit of detection (LOD), and limit of quanti 󿬁 cation (LOQ) of Cd 2+ ion werefound to be 2.93µAµM − 1 cm − 2 , 32.0 ± 1.62pM, and 106.67pM respectively. This novel approach might pavethe way for the development of heavy metal ion detection process in the 󿬁 elds of environmental and healthcare.

Heavy metal pollution is one of the most serious concerns to human health because these substances are toxic and retained by the ecological system. Many efforts have been taken over the past few years for the detection of heavy metal ions in the environment. Incorporation of DNAzymes/DNA molecules (including T-T or C-C mismatches and G-quadruplexes) and nanomaterials into sensors can lead to significant improvement in the performance of sensors in terms of sensitivity, selectivity, multiplexed detection capability and portability. This review presents a recent advance in biosensors based on DNAzymes/DNA molecules functionalized nanostructures for heavy metal detection. Furthermore, advances in biosensing devices/chip based on this method for the detection of metal ions are summarized. This paper highlights the strategies for design of heavy metal biosensors benefiting from the use of DNAzymes/DNA molecules and nanomaterials.