Development of "Imprint-and-Report" Dynamic Combinatorial Libraries for Differential Sensing Applications.

Sensor arrays using synthetic receptors have found great utility in analyte detection, resulting from their ability to distinguish analytes based on differential signals via indicator displacement. However, synthesis and characterization of receptors for an array remain a bottleneck in the field. Receptor discovery has been streamlined using dynamic combinatorial libraries (DCLs), but the resulting receptors have primarily been utilized in isolation rather than as part of the entire library, with only a few examples that make use of the complexity of a library of receptors. Herein, we demonstrate a unique sensor array approach using "imprint-and-report" DCLs that obviates the need for receptor synthesis and isolation. This strategy leverages information stored in DCLs in the form of differential library speciation to provide a high-throughput method for both developing a sensor array and analyzing data for analyte differentiation. First, each DCL is templated with analyte to give an imprinted library, followed by in situ fluorescent indicator displacement analysis. We further demonstrate that the reverse strategy, imprinting with the fluorescent reporter followed by displacement with each analyte, provides a more sensitive method for differentiating analytes. We describe the development of this differential sensing system using the methylated Arg and Lys post-translational modifications (PTMs). Altogether, 19 combinations of 3-5 DCL data sets that discriminate all 7 PTMs were identified. Thus, a comparable sensor array workflow results in a larger payoff due to the immense information stored within multiple noncovalent networks.

Achieving High Affinity and Selectivity for Asymmetric Dimethylarginine by Putting a Lid on a Box.

The methylation states of Lys and Arg represent a particularly challenging set of targets to distinguish selectively in water using synthetic receptors. To date, trimethyllysine (Kme3) is the only post translational modification (PTM) of the eight possible methylation states of Lys and Arg that can be recognized selectively. Here, we report the first synthetic receptor capable of selectively recognizing asymmetric dimethylarginine (Rme2a). This was achieved by using a biased dynamic combinatorial chemistry (DCC) library to generate a receptor mimicking the 5-sided box-like shape of Rme2 reader proteins, a feature that has been hypothesized to impart selectivity. Additionally, we synthesized a thioether-linked analogue of the resulting receptor to provide a novel scaffold with maintained selectivity but greater stability. This work introduces strategies that can be applied towards achieving selectivity based on subtle differences in hydrophilic guests in aqueous solutions.

Using changes in speciation in a dynamic combinatorial library as a fingerprint to differentiate the methylation states of arginine.

Herein we describe the development of a sensor array that utilizes the complex response of a dynamic combinatorial library (DCL) to discriminate all of the methylation states of Arg, previously unreported in a sensor array, as well as the methylation states of Lys. We find that the use of all species in the DCL, not just those that bind, allows for discrimination of analytes that are otherwise indistinguishable, demonstrating the value of utilizing a complex network of species for differential sensing.