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Derivatization of 2D materials for bioapplications is at the forefront of nanomaterials research nowadays. Facile synthesis of the biografted 2D derivatives and insight into the conformation of the conjugated biomolecules are two pillars, promoting advances in the field of biosensing, drug delivery and regeneration techniques. This work is devoted to the synthesis and conjugation of carboxylated graphene by aptamers followed by theoretical analysis of their conformation in the immobilized state. Employing the developed method, the hole-matrixed graphene with up to 11.1 at.% reactive carboxyl groups was synthesized and thoroughly examined via core-level spectroscopy and time-resolved methods. The mechanism of the performed carboxylation with conversion of graphene oxide into carboxylated graphene is proposed, unveiling commonly disregarded impact of ether-like components to the fingerprints of the carboxyl groups. We show successful covalent immobilization of the AO-01 aptamer against Hepatitis B protein on the synthesized C-xy graphene and for the first time reveal its conformation both in free and immobilized forms via a combination of density functional theory (DFT) calculations and molecular dynamic (MD) modeling. Taken together, these results advance the application of graphene derivatives grafted with the biomolecules in the field of biosensing.

Here, the synthesis of holey carbonylated (C-ny) graphene derivative and its application for gas sensing is demonstrated. The carbonylation of graphene oxide leads to the 3-fold increase in the concentration of carbonyl groups’ up to 9 at.% with a substantial elimination of other oxygen functionalities. Such a chemical modification is accompanied by the perforation of the graphene layer with the appearance of matrices of nanoscale holes, leading to corrugation of the layer and its sectioning into localized domains of the π-conjugated network. Combined with the predominant presence of carbonyls, granting the specificity in gas molecules adsorption, these features result in the enhanced gas sensing properties of C-ny graphene at room temperature with a selective response to NH3. Opposite chemiresistive response towards ammonia when compared to other analytes, such as ethanol, acetone, CO2, is demonstrated for the C-ny graphene layer both in humid and dry air background. Moreover, a selective discrimination of all of the studied analytes is further approached by employing a vector signal generated by C-ny multielectrode chip. Comparing the experimental results with the calculations performed in framework of density functional theory, we clarify the effect of partial charge transfer caused by water and ammonia adsorption on the chemiresistive response.