No abstract

An array sensing scheme for the differentiation of small peptides and their phosphorylated analogues is introduced. The technique involves a series of receptors created by appending random peptides to a C(3v) symmetric scaffold that binds phosphomonoesters. Five specific peptide sequences were selected through a screening technique. In addition to cross reactivity being created by the peptides in the receptors, three metal ions and three pH indicators are used to create a suite of 45 indicator displacement assays. The colorimetric data from the 45 sensing ensembles is collected in a 96-well plate reader, and linear discriminant analysis gives patterns resulting in 100% classification of the peptides. The approach demonstrates a generalizable principle to create pattern-based recognition protocols for complex analytes.

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[diagram: see text] Using a boronic acid receptor that was previously found to have high affinity for gluconic acid, we created a colorimetric indicator displacement assay (IDA) that can report the concentration of the product of glucose oxidase (GOx) catalyzed glucose oxidation. The color change obtained directly reflects the concentration of glucose. Our sensing ensemble was then successfully applied to determine the glucose concentration in human serum, which offers a facile, colorimetric, sensitive, and accurate glucose test.

[structure: see text] A cadmium-centered tris-boronic acid receptor was synthesized, and its binding properties toward various anionic sugars were determined. This receptor shows high affinity for different anionic sugars, especially gluconic acid, which has an association constant near approximately 10(7) M(-)(1) at neutral pH. Further, using an indicator displacement assay, a color change of pyrocatechol violet was observed upon addition of anionic sugars. This colorimetric test was used as a facile screening technique to qualitatively analyze guest affinities.