An electrochemical DNA biosensor for trace amounts of mercury ion quantification

Heavy Metal Ions Detection Using Nanomaterials-Based Aptasensors

Heavy metals ions as metallic pollutants are a growing global issue due to their adverse effects on the aquatic ecosystem, and human health. Unfortunately, conventional detection methods such as atomic absorption spectrometry exhibit a relatively low limit of detection and hold numerous disadvantages, and therefore, the development of an efficient method for in-situ and real-time detection of heavy metal residues is of great importance. The aptamer-based sensors offer distinct advantages over antibodies and emerged as a robust sensing platform against various heavy metals due to their high sensitivity, ease of production, simple operations, excellent specificity, better stability, low immunogenicity, and cost-effectiveness. The nucleic acid aptamers in conjugation with nanomaterials can bind to the metal ions with good specificity/selectivity and can be used for on-site monitoring of metal ion residues. This review aimed to provide background information about nanomaterials-based aptasensor, recent advancements in aptamer conjunction on nanomaterials surface, the role of nanomaterials in improving signal transduction, recent progress of nanomaterials-based aptasening procedures (from 2010 to 2022), and future perspectives toward the practical applications of nanomaterials-based aptasensors against hazardous metal ions for food safety and environmental monitoring.

DNA as a Next-Generation Biomonitoring Tool of Hospital Effluent Contamination

A DNA biosensor based on a modified gold electrode with a Au/cysteine/DNA matrix was developed for ultratrace determination of genotoxicity antibiotics. The modified Au/cysteine/DNA electrode was characterized by cyclic voltammetry and impedance spectroscopy methods. The interaction between immobilized DNA and genotoxicity antibiotics in hospital wastewater was investigated using differential pulse voltammetry (DPV) technology. Using this technique, ciprofloxacin and ofloxacin were detected in real time in the hospital wastewater (HW) of the Tunisian cities of Gabes, Tozeur, Sfax, and Gbeli. In addition, physicochemical parameters such as the chemical oxygen demand (COD), biological oxygen demand (BOD), and total organic carbon (TOC) of HW samples that may affect the nature of the samples were studied. Comet assay (single-cell gel electrophoresis) was performed to measure the capacity of xenobiotics to induce DNA damage. In our conditions, this test indicated that all tested wastewater was able to alter cell integrity and cause DNA molecular damage, and the most genotoxic effect was found in the wastewater of Gabes hospital. Results show that the concentrations of the two antibiotics reached 33 and 40 ng/mL in the hospital wastewater of Gabes and Tozeur, respectively. The DNA biosensor based on the modified gold electrode exhibited superb performance and offers a probable application for the detection of genotoxicity antibiotics in hospital wastewater. The level of genotoxicity is proportional to the concentration of antibiotics detected in hospital wastewater. We will explore the application of this model for continuous monitoring downstream of hospital discharge and wastewater treatment plants for effective control of the presence of genotoxic products.

Rationally engineered nanosensors: A novel strategy for the detection of heavy metal ions in the environment

Heavy metal ions (HMIs) have been mainly originated from natural and anthropogenic agents. It has become one of biggest societal issues due to their recognised accumulative and toxic effects in the environment as well as biological media. Key measures are required to reduce the risks posed by toxic metal pollutants existing in the environment. The increased research activities of HMIs detection, and use of technologies based on electrochemical detection that combine with engineered nanomaterials, is a key promising and innovative strategy that can potentially confine heavy metal poisoning. Deep understanding of the characteristics of the physicochemical properties of nanomaterials is highly required. It is also important to interpret the parameters at the nano-bio interface level that merely affect cross-interactions between nanomaterials and HMIs. Therefore, the authors outlined the state-of-the-art techniques that used engineeringly developed nanomaterials to detect HMIs in the environment. The possible novel applications of extensive and relatively low-cost HMIs monitoring and detection are discussed on the basis of these strengths. Finally, it is concluded by providing gist on acquaintance with facts in the present-day scenario along with highlighting areas to explore the strategies to overcome the current limitations for practical applications is useful in further generations of nano-world.

Recent advances in the development of electrochemical aptasensors for detection of heavy metals in food

Heavy metal contamination in environment and food has attracted intensive attention from the public since it poses serious threats to ecological system and human health. Traditional detection methods for heavy metals such as atomic absorption spectrometry have a fairly low detection limit, but the methods have many limitations and disadvantages. Therefore, it is of significance to develop a rapid technology for real-time and online detection of heavy metals. The electrochemical aptasensor-based technology is promising in the detection of heavy metals with advantages of high sensitivity, specificity, and accuracy. Although its development is rapid, more researches should be carried out before this technology can be used for on-site detection. In this review, the origin, basic principles and development of electrochemical aptasensors are introduced. The applications of nanomaterials and electrochemical aptasensors for the detection of heavy metals (mainly mercury, lead, cadmium, and arsenic) are summarized. The research and application tendency of electrochemical aptasensors for detection of heavy metals are prospected.

Peptide nucleic acid as a selective recognition element for electrochemical determination of Hg2

A novel electrochemical PNA-based biosensor for the determination of Hg²⁺ is described. The receptor layer, containing single strands of polythymine PNA (peptide nucleic acid), was formed at the surface of gold electrode. Due to the presence of thymine bases and peptide bonds, an interaction between Hg²⁺ ion and receptor layer occurs. The influence of chain modification - PNA vs. DNA - and type of redox marker - anionic AQMS-Na (sodium salt of anthraquinone-2-sulfonic acid) and Fe^II/III (potassium ferri/ferrocyanide) or cationic MB (methylene blue) and RuHex (hexaammineruthenium(III) chloride) - were studied. Proposed PNA-based biosensor with anionic AQMS-Na as a redox marker demonstrated significantly better analytical parameters, as compared to results obtained for other tested redox markers (for measurements at pH6.0). The linear response towards Hg²⁺ was in the range from 5 to 500nmol·L^-1 with the detection limit of 4.5nmol·L^-1. The developed sensor distinguishes itself with high selectivity towards Hg²⁺, even for solutions containing several interfering cations. Interactions between Hg²⁺ and PNA receptor layer were studied using square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS).