Abstract
In this study, we synthesized molecularly imprinted mesoporous organosilica (MIMO) in the presence of a new precursor having a zwitterionic functional group and an imprint molecule, namely, glyphosate (MIMO-z). The precursor-glyphosate complex engaged in a typical base-catalyzed sol-gel reaction and the introduced zwitterion group remained intact in the framework after the extraction process had been completed. To test the rebinding performance of the target molecule, graphene quantum dots were encapsulated (MIMO-zQ) into pores and the fluorescence intensity change was monitored according to the concentration of glyphosate. When the MIMO-zQ suspension was diluted into the glyphosate solutions, notable fluorescence quenching occurred, right down to sub-nanomolar levels of concentration; 9.2 ± 0.18% quenching at 0.1 nM (0.017 ppb, 17 pg/mL). This result is one of the best reported to date for sensing using MIMO. The synthesized probe also exhibited a distinct signal compared to a series of competing compounds, aminomethylphosphonic acid and glycine; 4.3 ± 0.019% and 3.7 ± 0.041% quenching at 100 nM.
Highlights
One of the most controversial nonselective herbicides which has potential carcinogenicity[1] and endocrine disruption[2] in humans is 2-(Phosphonomethylamine)acetic acid
Its high pore volume and nano-sized wall thickness allow for the introduction of quantum dots (QD) in the vicinity of the imprinted cavities located on the framework
Each QD has different emission wavelength and size, and thereby we confirmed that the size of QD relates to the recognition performance
Summary
One of the most controversial nonselective herbicides which has potential carcinogenicity[1] and endocrine disruption[2] in humans is 2-(Phosphonomethylamine)acetic acid (glyphosate, Glyp). The delicate cavities on the surface were not imprinted and formed to the degree sought by the simple addition of imprint molecule during the sol-gel reaction with the tetraalkyl silicates[25] To overcome this difficulty, Davis’s and Chang’s group suggested that the imprint molecule derivative silane precursors ought to be introduced into the reaction process in order to be involved in the silica formation[26,27]. Davis’s and Chang’s group suggested that the imprint molecule derivative silane precursors ought to be introduced into the reaction process in order to be involved in the silica formation[26,27] These were observed to have sacrificial carbamate bonds with the (3-aminopropyl)triethoxysilane which can be broken down through hydrolysis to remove only the imprint molecules. Quantum dots encapsulated in pores are used as a signal transducer to detect levels of target sensitively by monitoring the fluorescence quenching behavior, as it responds to the concentration of analytes dissolved in de-ionized water
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