Recent Advances in Organic Sensors for the Detection of Ag+ Ions: A Comprehensive Review (2019-2023)

Recently, organic sensors for the detection of Ag+ and other metal ions have experienced significant advancements. This is because there is a growing demand for reliable and sensitive tools to monitor various environmental pollutants. Organic sensors have O-, S-, and N-donor atoms, which can act as a ligand and coordinate with different metal ions, hence stabilizing them in a variety of oxidation states. This interaction gives colorimetric and fluorescence changes, which are used to monitor Ag+ and other metal ions. This comprehensive review highlights the latest developments in organic sensors for the recognition of Ag+. We present an in-depth analysis of the underlying principles and mechanisms governing Ag+ ion recognition. Various organic sensing platforms, such as fluorescent and colorimetric sensors, are discussed, shedding light on their unique advantages and limitations. Special attention is given to the diverse range of organic ligands, receptors, and functional materials used to achieve high sensitivity, selectivity, and quantification accuracy. Additionally, we delve into real-world applications of organic sensors for Ag+ ion detection, examining their performance in complex matrices such as biological, environmental, industrial and agricultural matrices.

In Vivo Chemogenetic Biocompatibility of Mercury as a Specific Hypercalcemia Actuator in Snail's Spinal Cord Cell Manipulation: An Extracellular Field Potential Biosensor

The in vivo chemogenetic property of mercuric ions (Hg²⁺) was investigated as a specific hypercalcemia actuator in snail's spinal cord cell manipulation by extracellular field potential biosensing analysis. For this purpose, a three-microelectrode system with working, counter, and pseudo reference electrodes was blindly implanted into the snail's spinal cord to electrically stimulate (triggering) the action potential with a staircase electrical voltage at a very low frequency level, along with measurement of the electrical current, as a detection system. Under optimum conditions, using the one-factor-at-a-time method, a wide linear range between 1.0 × 10^-14 and 1.0 × 10^-1 mol L^-1 with correlation coefficients (R²) >0.98 and a response time (t₉₀) of maximum 10.0 s were approximated. Percentages of relative standard deviation were estimated to be 3.08 (reproducibility, n = 50) and 7.31 (repeatability, n = 15). The detection limit was estimated to be sub 2.1 × 10^-16 mol L^-1 based on the X_b^- + 3S_b definition. The reliability of this phenomenon was evidenced by the estimation of recovery percentages (between 95 and 107%) during spiking Hg²⁺ standard solutions. The probable mechanism behind this process could be attributed to the following: (i) the neuronal ephaptic coupling during electrical synchronization by a specific brain-triggered wave as a neuronal motor toolkit and (ii) chemical synchronization using a Hg²⁺ hypercalcemia actuator (biosensor). Linear correlation has been evidenced during interactions between Hg²⁺ and a calcium ionic channel's protein with a gram molecular weight of 66.2 ± 0.3 KCU. This process, therefore, caused an opening of the Ca²⁺ channel gates and majorly released the Ca²⁺ (hypercalcemia) that was detected as the main source of the measured electrical current. At this condition, ultratrace levels of Hg²⁺ ions not only were considered as nontoxic reagents but also had chemically regulating effects as ephaptic synchronizers to the neuron cells. This report may pave the way for using mercury ions at an ultratrace level for clinical controlling purposes during neuronal spinal cord cell manipulation.

Optimization of analytical procedures for the simultaneous voltammetric determination of total Hg(II) in presence of Cu(II) in environmental matrices

The present work reports the critical comparison about the employment of three different supporting electrolytes (0.1 mol L−1 HClO4, 0.01 mol L−1 EDTA-Na2 + 0.06 mol L−1 NaCl + 2.0 mol L−1 HClO4 and 0.1 mol L−1 KSCN + 0.001 mol L−1 HClO4) and their instrumental and chemical optimisation for the simultaneous voltammetric determination of total mercury(II) and copper(II) in sediments and sea water at gold electrode, especially discussing the reciprocal interference problems.

The differential pulse anodic stripping voltammetric (DPASV) measurements were carried out using a conventional three-electrode cell: a gold electrode (GE) as working electrode, a platinum wire and an Ag‖AgCl‖KClsat as auxiliary and reference electrodes, respectively.

The analytical procedure was verified by the analysis of standard reference materials: Estuarine Sediment BCR-CRM 277, River Sediment BCR-CRM 320 and Mercury in Water NIST-SRM 1641d.

Once set up on the standard reference materials, the analytical procedure was transferred and applied to sediments and sea waters sampled in a lagoon ecosystem connected with Adriatic Sea (Ravenna area, Italy).