A simple and rapid colorimetric method for the determination of Mn2+ based on pyrophosphate modified silver nanoparticles

Recent Developments in Colorimetric and Fluorimetric Chemosensors for the Detection of Mn2+ Ions: A Review (2010-2024)

Manganese is an essential metal ion involved in various biological and environmental processes, but its excess can lead to toxicity, particularly affecting the nervous system. Therefore, developing selective and sensitive detection methods for Mn2+ ions is of paramount importance. Colorimetric and fluorimetric chemosensors have emerged as promising tools for the detection of Mn2+ due to their simplicity, cost-effectiveness, and real-time monitoring capabilities. This review discusses recent advances in the colorimetric and fluorimetric chemosensors that exhibit distinct color or fluorescence changes upon interaction with Mn2+ ions. The review explores different organic and nanomaterials, focusing on their mechanisms of sensing, sensitivity, selectivity, and practical applications in environmental monitoring, healthcare, and food safety. The article also provides insights into future research directions aimed at overcoming these challenges, improving chemosensor performance, and expanding the applicability of colorimetric and fluorimetric chemosensors for Mn2+ detection in diverse real-world scenarios.

Electrochemical detection of manganese ions using aptamer-based layers

Heavy metals are one of the major pollutants found in drinking water and their abnormal level may pose a threat to human's health and life. Manganese also belongs to heavy metals group, and it is generally used in production of batteries, fertilizers, and ceramics. Even though, Mn is necessary for proper development of central nervous system, its elevated concentration might lead to certain diseases such as epilepsies, cell death in focal cerebral ischemia as well as neurodegenerative diseases such as Huntington and Alzheimer. Hence, it is crucial to elaborate novel methods for manganese ions detection that could be applied for in situ analysis of water samples. Herein, we present the studies on the electrochemical detection of manganese ions using aptamer-modified electrodes. This is the first attempt of application of aptamer strands as receptor layers for electrochemical analysis of manganese ions and for that purpose gold disk electrodes served as transducers, which were further modified with disulfide - based aptamers and 6-mercapto-1-hexanol blocking agent. The electrochemical measurements concerned the choice of the conditions for formation of aptamer receptor layer as well as the type of redox indicator that served as the source of current signal. The studies referred to the definition of aptasensor working parameters including the verification of the possibility of manganese ion detection in cell culture media. It was shown that it was possible to detect Mn2+ ions within 25 nM-1 μM concentration and the proposed aptasensor exhibited high selectivity towards target analyte for which at least 2 - times higher response was recorded than for interfering ions. Moreover, the possibility of Mn2+ detection in real samples was depicted followed by stability and regeneration studies.

A new fluorescent-colorimetric chemosensor based on a Schiff base for detecting Cr3+, Cu2+, Fe3+ and Al3+ ions

A new Schiff base derivative fluorescence-colorimetric chemosensor 2-hydroxy-5-[(2-hydroxy-1-naphthyl)methylideneamino]benzoic acid (H₃L), has been designed and synthesized. H₃L displayed high selectivity and sensitivity for detecting Cr³⁺, Cu²⁺, Fe³⁺ and Al³⁺ ions in DMF/H₂O (v/v = 1/1) solution. When Cr³⁺, Cu²⁺ or Fe³⁺ ions were added, the solution of H₃L in DMF/H₂O exhibited different color changes. While with the addition of Fe³⁺ or Al³⁺ ions, the solution of H₃L in DMF/H₂O displayed different fluorescence responses. The bonding modes and bonding ratios of H₃L and metal ions were explored by the Job's plot, ¹H NMR titration, and electrospray ionization mass spectrometry (ESI-MS). The detection limits of H₃L with Cr³⁺, Cu²⁺, Fe³⁺and Al³⁺ ions were 3.37 × 10^-7 M, 4.65 × 10^-7 M, 3.58 × 10^-7 M and 4.89 × 10^-7 M, respectively.

Development of a novel tridentate ligand for colorimetric detection of Mn2+ based on AgNPs

A novel tridentate ligand nitrilotris(methylene)tris(1,2,3-triazole)triacetate (NTTTA) has been synthesized by click reaction and followed with ester hydrolysis reaction. The silver nanoparticles (AgNPs) were then modified and stabilized by this ligand, and subsequently been employed for the highly selective and sensitive colorimetric detection of Mn²⁺ in aqueous solution. The presence of Mn²⁺ can cause the aggregation of AgNPs, which leads to the color change of the dispersion from yellow to brown, as well as the decrease and red-shift of the surface plasmon resonance absorption. The detection limit of Mn²⁺ was as approximately 0.5 μM by the naked eyes. UV-vis spectroscopy analysis showed a good linear relationship between the logarithm of the ratios (A₅₅₀/A₃₉₅) and the concentration of Mn²⁺over the range of 0.05 μM-10 μM, and the LOD was calculated to be 12.6 nM (S/N = 3). The present assay showed good simplicity without the need of adjusting the pH value. The feasibility of this technique was evaluated for successful detection of Mn²⁺ in tap water and lake water samples, with good recoveries.

A novel sensor for determination of naproxen based on change in localized surface plasmon peak of functionalized gold nanoparticles

A highly selective and sensitive colorimetric sensor for the determination of naproxen (NAP) based on the aggregation of the thiolated β-cyclodextrin (Tβ-CD) functionalized gold nanoparticles (Tβ-CD-Au NPs) in the presence of NAP and Zn²⁺is described. The hydrophobic end of NAP interacts with the immobilized Tβ-CD on the Au NPs and forms the complex of Tβ-CD:NAP while the Zn²⁺ ions form a 1:2 complex of (NAP)₂Zn with the carboxyl groups of NAP resulting in the aggregation of functionalized gold nanoparticles. As a result of aggregation, the localized surface plasmon resonance (LSPR) band of functionalized gold nanoparticles around 520nm decreases and a new red shifted band at 650nm appears which increases gradually as the function of NAP concentration. The calibration graph derived from the intensity ratios of absorbance at 650nm to 520nm was linear in the concentration range of 4-180μgL^-1of NAP. At the optimum conditions, the limit of detection (LOD) and quantification (LOQ) were found to be 0.6 and 2.1μgL^-1, respectively and the relative standard deviation at 20μgL^-1of NAP (n=5) was 2.5%. The selectivity and applicability of the method was verified through analyzes of the synthetic samples containing the major interference compounds reported in literature as well as tablets, wastewater and urine samples. The accuracy of the method was evaluated by recovery experiments and analysis of pharmaceutical tablets.