Optical sensor for the visual detection of mercury using mesoporous silica anchoring porphyrin moiety

Abstract

A low cost, solid optical sensor for the rapid detection of low concentrations of Hg2+ in aqueous media was prepared by the monolayer functionalization of mesoporous silica with 5,10,15,20-tetraphenylporphinetetrasulfonic acid (TPPS), anchored by N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TMAC). The detection is based on the color change of TPPS from orange to green as a result of the formation of a charge-transfer complex with Hg2+. The intensity of the charge-transfer band varies linearly with Hg2+ in the concentration range from zero to 2.5 x 10(-7) mol dm(-3). The lower detection limit observed for Hg2+ concentration is 1.75 x 10(-8) mol dm(-3). The material exhibits good chemical and mechanical stability, and did not show any degradation of TPPS for a period of eight months. The sensor was applied for the analysis of various environmental samples. The effects of pH, sample volume, reaction time, amount of material, and the presence of foreign ions on the detection method are discussed.

Rational Design of “Turn‐On” Allosteric DNAzyme Catalytic Beacons for Aqueous Mercury Ions with Ultrahigh Sensitivity and Selectivity

“…Each metal was tested at three concentrations (1,20, and 1000 mm). None of the metal ions gave responses higher than half of that produced by 20 nm Hg 2+ ions, and the selectivity was determined to be at least 100 000-fold higher for Hg 2+ ions over any other metal ions (10 nm Hg 2+ versus 1 mm competing metal ions).…”

“…[3,4] Only a few such sensors can detect Hg 2+ ions in water with high sensitivity and selectivity. [5] Hg 2+ -ion sensors based on foldamers, [6] oligonucleotides, [7] conjugated polymers, [8] genetically engineered cells, [9] enzymes, [10] antibodies, [11] transcriptional regulatory proteins, [12,13] DNAzymes, [14] and chemically modified optical fibers, [15,16] capillary optodes, [17] membranes, [18] electrodes, [19] mesoporous silica, [20] and nanoparticles [21] are also known. For environmental-monitoring applications, such as detection of Hg 2+ ions in drinking water, a detection limit of lower than 10 nm (the toxic level defined by the U.S. Environmental Protection Agency (EPA)) is required.…”

Novel Grafting onto Silica via Aldehyde Functionality

“…Their photochemical characteristics in the visible spectrum make functionalized porphyrins useful for the collection and conversion of photochemical energy in solar cells [14]. They have also been used as catalysts that mimic the activity of enzymes [15] as mechanical components in molecular machinery [16] as a low cost, solid optical sensor for the rapid detection of low concentrations of Hg +2 in aqueous media [17] and as components in supramolecular architecture [18]. When used as a sensor the detection mechanism of the porphyrins is based on a color change as a result of the formation of a chargetransfer complex with the trapped metal ion.…”

Micro- and nanostructured sol-gel-based materials for optical chemical sensing (2005–2015)

“…TEOS-based material was also exploited in colorimetric Zn 2+ and Fe 2+ detection. The 1,5-diphenylcarbazone was used in Zn 2+ determination [134]. The authors investigated suitability of both acid-and base-catalysed sol-gel process and they found that leaching did not occur when acid was used as a catalyst.…”