Directed Evolution of the Optoelectronic Properties of Synthetic Nanomaterials

Abstract

Directed evolution is a powerful approach for tailoring protein properties toward new or enhanced functions. This technique allows one to alter a protein in a directed manner even in the absence of a known relationship between protein structure and function. Several nanocomplexes, such as optical sensors based on DNA-wrapped single-walled carbon nanotubes (DNA-SWCNTs), similarly lack a known structure-function relationship. For example, DNA-SWCNT complexes exhibit variations in their fluorescence that depend on the sequence of the DNA wrapping. However, little is known about the relationship between the DNA sequence and its effects on the fluorescence properties of SWCNTs. In this study, we use directed evolution as a guided approach to tuning the optoelectronic properties of DNA-SWCNT complexes through DNA mutation. Applying this technique over two rounds of DNA mutagenesis and screening, we evolved a DNA-SWCNT sensor with a 57% enhancement in fluorescence intensity. Furthermore, this sensor shows retained selectivity and sensitivity towards the analyte of interest. Though we demonstrate this approach to improve sensor brightness, directed evolution offers far-reaching possibilities in the field that can also be applied to improve additional sensor properties such as sensitivity and selectivity.