2023 AIChE Annual Meeting
Identifying the Efficacy of Mutants of the De Novo Protein S824 As Capping Ligands for the Biosynthesis of CdS Quantum Dots
Quantum dots are ideal for biomedical applications such as fluorescent cell labeling, targeted drug delivery, and precision imaging therapy. However, the use of quantum dots is currently limited due to the high toxicity of chemicals used in synthesis. To make quantum dots biocompatible, several biological synthesis routes, such as biomineralization, have been used to produce quantum dots using proteins. While effective, these routes are currently limited to specific metal sulfide materials because only a few proteins have been identified and applied to control quantum dot synthesis. Here, we aim to identify new mutated proteins to expand and improve upon the quality and materials palette of quantum dots that can be produced using biomineralization. We utilized site-directed mutagenesis, transformation, and recombinant protein expression to synthesize mutated proteins of interest. Specifically, we identified and tested mutants of the de novo protein S824. Multiple mutants of interest were observed to stabilize CdS quantum dots and maintain quantum confinement as shown by UV-Vis spectroscopy. We screened proteins of interest with Na2S and Cd2+ to identify quantum confined CdS complexes using spectra data. We assessed binding strength of the proteins using centrifuging exclusion and biolayer interferometry. Ultimately, we hope to identify amino acid sequence motifs that correlate to a strong metal binding affinity of naturally evolved proteins to apply them in later research involving "designer" engineered proteins for quantum dot capping.