Functionalized Ionic Microgel Sensor Array for Colorimetric Detection and Discrimination of Metal Ions

Abstract

A functional ionic microgel sensor array was developed by using 1-(2-pyridinylazo)-2-naphthaleno (PAN)- and bromothymol blue (BTB)-functionalized ionic microgels, which were designed and synthesized by quaternization reaction and anion-exchange reaction, respectively. The PAN microgels (PAN-MG) and BTB microgels (BTB-MG) were spherical in shape with a narrow size distribution and exhibited characteristic colors in aqueous solution in the presence of various trace-metal ions, which could be visually distinguished by the naked eye. Such microgels could be used for the colorimetric detection of various metal ions in aqueous solution at submicromolar levels, which were lower than the U.S. Environmental Protection Agency standard for the safety limit of metal ions in drinking water. A total of 10 species of metal ions in aqueous solution, Ba, Cr, Mn, Pb, Fe, Co, Zn, Ni, Cu, and Al, were successfully discriminated by the as-constructed microgel sensor array combined with discriminant analysis, agglomerative hierarchical clustering, and leave-one-out cross-validation analysis.

Anion identification using silsesquioxane cages

“…Principal component analysis (PCA) was used to create association fingerprints for anions with AnSQ. 35 , 36 Input data were emission spectra obtained at λ ex = 370 nm of the sample minus the blank in each solvent (acetone, DCM, DMF, DMSO, THF, THF/H 2 O and toluene). In each solvent, spectra of 6 μM AnSQ were measured before and after addition of 100 equiv.…”

Contrast variation SANS measurement of shell monomer density profiles of smart core–shell microgels

“…[1][2][3][4][5][6][7][8][9][10] This behaviour grants them the adjective smart. The response of these materials has great potential in the context of different applications like smart catalyst carriers, [11][12][13] drug delivery, 14,15 sensors, [16][17][18] optical devices, [19][20][21] responsive surface coatings 22 and actuators 23 or in biomedical applications. 24 Combining two monomers of different transition temperatures in statistical copolymers can be used to tune the swelling transition temperature, [25][26][27][28][29] whereas the subsequent synthesis of core and then shell 27,30-35 may lead to a continuous, linear temperature dependent swelling.…”

Array-Based Discriminative Optical Biosensors for Identifying Multiple Proteins in Aqueous Solution and Biofluids

“…One way to achieve discriminative sensing is to develop multi-element sensor arrays, which are inspired by mimicking mammalian taste and smell systems and usually consist of multiple cross-reactive elements that generate a combined recognition pattern for each analyte (Stewart et al, 2013 ; Peveler et al, 2016 ; Rana et al, 2016 ). Another way to realize discriminative sensing is to fabricate an environment-sensitive sensor array, which is constructed by changing the solvents (Cao et al, 2014b , 2020 ; Smith et al, 2019 ), probe concentrations (Li et al, 2014 ), or pH values and ionic strengths (Liu et al, 2017 ; Tomita et al, 2017 ; Zhou et al, 2017 ; Lin et al, 2019 ). The third type of discriminative sensing is multi-wavelength cross-reactive single-system-based sensors, which use multiple wavelengths instead of multi-elements to provide response signals (Wu et al, 2011 ; Rout et al, 2012 ).…”