RT Journal Article
SR Electronic
T1 Graphene Quantum Dot Oxidation Governs Noncovalent Biopolymer Adsorption
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 684670
DO 10.1101/684670
A1 Sanghwa Jeong
A1 Rebecca L. Pinals
A1 Bhushan Dharmadhikari
A1 Hayong Song
A1 Ankarao Kalluri
A1 Debika Debnath
A1 Wu Qi
A1 Moon-Ho Ham
A1 Prabir Patra
A1 Markita P. Landry
YR 2019
UL http://biorxiv.org/content/early/2019/06/27/684670.abstract
AB The graphene quantum dot (GQD) is a carbon allotrope with a planar surface amenable for functionalization and nanoscale dimensions that confer photoluminescent properties. Collectively, these properties render GQDs an advantageous platform for nanobiotechnology applications, including as optical biosensors and delivery platforms. In particular, noncovalent functionalization offers a route to reversible modification and preservation of the pristine GQD substrate. However, a clear paradigm for GQD noncovalent functionalization has yet to be realized. Herein, we demonstrate the feasibility of noncovalent polymer adsorption to the GQD surface, with a specific focus on single-stranded DNA (ssDNA). We study how GQD oxidation level affects the propensity for polymer adsorption by synthesizing and characterizing four types of GQD substrates and investigating noncovalent polymer association to these substrates. Distinct adsorption methods are developed for successful ssDNA attachment based upon the GQD’s initial level of oxidation. ssDNA adsorption to the GQD is confirmed by atomic force microscopy, by inducing ssDNA desorption, and with molecular dynamics simulations. ssDNA is determined to adsorb strongly to no-oxidation GQDs, weakly to low-oxidation GQDs, and not at all for heavily oxidized GQDs. We hypothesize that high GQD oxygen content disrupts the graphitic carbon domains responsible for stacking with the aromatic ssDNA bases, thus preventing the formation of stable polymer-GQD complexes. Finally, we develop a more generic adsorption platform and assess how the GQD system is tunable by modifying both the polymer sequence and type.