Sodium Dodecyl Sulfate Doped Polyaniline for Enhancing the Electrochemical Sensitivity of Mercury Ions

Polyaniline-based bovine serum albumin imprinted electrochemical sensor for ultra-trace-level detection in clinical and food safety applications

Monitoring bovine serum albumin (BSA) at ultra-low levels is crucial for clinical and food safety applications, as it plays a significant role in identifying various health conditions and potential risks, necessitating fast, trace-level detection of BSA. This study proposes an approach to address these challenges by employing molecularly imprinted polymer (MIP) to develop an ultra-trace-level and cost-effective BSA sensing platform. The MIP electrochemical sensor was developed using polyaniline (PANI) combined with the protein crosslinker glutaraldehyde (GA) to optimize BSA surface imprinting in the MIP. As a result, the sensor achieves a sensitivity of 1.24 μA/log(pg/mL), with a picomolar detectable limit of 2.3 pg/mL (0.035 pM) and a wide detection range from 20 pg/mL to 200,000 pg/mL (0.303 pM to 3030 pM), making it suitable for clinical and food safety applications. Additionally, the study explores the interaction between an acidic surfactant protein eluent (acetic acid with sodium dodecyl sulfate, AcOH-SDS) and BSA vacant sites, enhancing recognition and re-binding. The PANI-based MIP sensor demonstrates initial feasibility and practicality in commercial milk and real human serum, opening avenues for early disease detection and ensuring food safety in BSA-related immune responses.

Microfluidic Devices for Heavy Metal Ions Detection: A Review

The contamination of air, water and soil by heavy metal ions is one of the most serious problems plaguing the environment. These metal ions are characterized by a low biodegradability and high chemical stability and can affect humans and animals, causing severe diseases. In addition to the typical analysis methods, i.e., liquid chromatography (LC) or spectrometric methods (i.e., atomic absorption spectroscopy, AAS), there is a need for the development of inexpensive, easy-to-use, sensitive and portable devices for the detection of heavy metal ions at the point of interest. To this direction, microfluidic and lab-on-chip (LOC) devices fabricated with novel materials and scalable microfabrication methods have been proposed as a promising approach to realize such systems. This review focuses on the recent advances of such devices used for the detection of the most important toxic metal ions, namely, lead (Pb), mercury (Hg), arsenic (As), cadmium (Cd) and chromium (Cr) ions. Particular emphasis is given to the materials, the fabrication methods and the detection methods proposed for the realization of such devices in order to provide a complete overview of the existing technology advances as well as the limitations and the challenges that should be addressed in order to improve the commercial uptake of microfluidic and LOC devices in environmental monitoring applications.

Screen-printed electrochemical sensors for environmental monitoring of heavy metal ion detection

Heavy metal ions (HMIs) are known to cause severe damages to the human body and ecological environment. And considering the current alarming situation, it is crucial to develop a rapid, sensitive, robust, economical and convenient method for their detection. Screen printed electrochemical technology contributes greatly to this task, and has achieved global attention. It enabled the mass transmission rate and demonstrated ability to control the chemical nature of the measure media. Besides, the technique offers advantages like linear output, quick response, high selectivity, sensitivity and stability along with low power requirement and high signal-to-noise ratio. Recently, the performance of SPEs has been improved employing the most effective and promising method of the incorporation of different nanomaterials into SPEs. Especially, in electrochemical sensors, the incorporation of nanomaterials has gained extensive attention for HMIs detection as it exhibits outstanding features like broad electrochemical window, large surface area, high conductivity, selectivity and stability. The present review focuses on the recent progress in the field of screen-printed electrochemical sensors for HMIs detection using nanomaterials. Different fabrication methods of SPEs and their utilization for real sample analysis of HMIs using various nanomaterials have been extensively discussed. Additionally, advancement made in this field is also discussed taking help of the recent literature.

A Review of Microfluidic Detection Strategies for Heavy Metals in Water

Heavy metal pollution of water has become a global issue and is especially problematic in some developing countries. Heavy metals are toxic to living organisms, even at very low concentrations. Therefore, effective and reliable heavy metal detection in environmental water is very important. Current laboratory-based methods used for analysis of heavy metals in water require sophisticated instrumentation and highly trained technicians, making them unsuitable for routine heavy metal monitoring in the environment. Consequently, there is a growing demand for autonomous detection systems that could perform in situ or point-of-use measurements. Microfluidic detection systems, which are defined by their small size, have many characteristics that make them suitable for environmental analysis. Some of these advantages include portability, high sample throughput, reduced reagent consumption and waste generation, and reduced production cost. This review focusses on developments in the application of microfluidic detection systems to heavy metal detection in water. Microfluidic detection strategies based on optical techniques, electrochemical techniques, and quartz crystal microbalance are discussed.

Poly(1,5-Diaminonaphthalene)-Modified Screen-Printed Device for Electrochemical Lead Ion Sensing

Poly(1,5-diaminonaphthalene) has been electropolymerized on the screen-printed device with a three-electrode configuration. The modified electrodes have been developed as the new electrode for electrochemical determination of trace levels of lead ions (Pb2+). The poly(1,5-diaminonaphthalene) film prevents the deposition of Pb2+ into the surface defects of the bare carbon screen-printed electrode and possesses sensitivity to heavy metal ions thanks to amine and secondary amino groups on the polymer chain. The square wave anodic stripping voltammetry was applied to detect Pb2+ ions, showing a sharp stripping peak with the linear range from 0.5 μg·L-1 to 5.0 μg·L-1 ( $R^2=0.9929$ ). The limit of detection was found to be 0.30 μg·L-1. The sensors were applied to the analysis of Pb2+ in the tap water sample matrix with satisfactory results.

Electrochemical microfluidics techniques for heavy metal ion detection

Heavy metals refer to metals with a density above 5 × 103 kg m-3, such as lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg). Even a trace amount of heavy metals is detrimental to human health. With the increasing significance of detection of heavy metals, the use of the electrochemical detection technique combined with microfluidics is a promising strategy and has thus attracted wide attention from academia and is the subject of this review. First, this review introduces the basics of electrochemical detection and microfluidics. Second, this review presents and evaluates a variety of electrochemical microfluidics technologies for heavy metal ions detection that are user friendly, portable, inexpensive, and easy to manufacture compared to traditional methods. The categorization is based on different detected ions in the order of Pb, Cd, As, Hg, Mn, and Zn. Finally, the author summarizes the development of detection technology in recent years and puts forward a perspective for the future prospects.

Exciton energy transfer-based fluorescent sensor for the detection of Hg2+ through aptamer-programmed self-assembly of QDs

Herein, an original exciton energy transfer-based sensitive fluorescence sensor for the determination of Hg²⁺ has been designed through DNA aptamer-programmed self-assembly of CdTe quantum dots (QDs). In this work, CdTe QDs were applied as fluorescence signal source. The two pieces of T-rich aptamer played a role as molecular recognition probes which could bind to the target Hg²⁺ specifically. The extent of Hg²⁺-triggered self-assembly of QDs depended on the concentration of Hg²⁺, which resulted in an exciton energy transfer effect between QDs, giving an obvious fluorescence signal decrease and red-shift of the fluorescent peak. Based on this principle, we could detect the Hg²⁺ in two different signal modes. The limit of detection (LOD) was 3.33 nM. The proposed sensing method exhibited its application in detecting Hg²⁺ in real water samples with satisfactory performance. The results indicated that this proposed sensor will be of great potential in biological and analytical fields.

Electrochemical Hg2+ detection at tannic acid-gold nanoparticle modified electrodes by square wave voltammetry

We report the electrochemical sensing of Hg²⁺ based on tannic acid capped gold nanoparticle (AuNP@TA) complexes.