Confined Reduced Graphene Oxides as a Platform for DNA Sensing in Solutions Crowded with Biomolecules

Promising systems for simple biomolecular sensing rely on the adsorption of probe DNAs onto graphene oxides (GOs). However, in biological samples crowded with nontarget biomolecules, the systems suffer from nonspecific displacement of the adsorbed probe DNAs by those crowding biomolecules, which is a major obstacle for practical application. Herein, we demonstrate DNA sensing in solutions crowded with biomolecules, such as concentrated protein solutions and even serum, using reduced GOs (rGOs) confined within robust networks of crystalline cellulose oligomers. The confinement of GOs was conducted with concomitant reduction in one step via the enzymatic cellulose oligomer synthesis. The confined rGOs could adsorb probe DNAs more tightly than could GOs due to higher hydrophobicity while being prevented from aggregation even in water by the confinement effect, allowing for sensing in solutions crowded with biomolecules. The sensitivity was comparable to that of the original GO-based sensing in clean buffer solutions. This study paves the way for simple biomolecular sensing in biological samples.