Breaking the barrier to biomolecule limit-of-detection via 3D printed multi-length-scale graphene-coated electrodes

Sensing of clinically relevant biomolecules such as neurotransmitters at low concentrations can enable an early detection and treatment of a range of diseases. Several nanostructures are being explored by researchers to detect biomolecules at sensitivities beyond the picomolar range. It is recognized, however, that nanostructuring of surfaces alone is not sufficient to enhance sensor sensitivities down to the femtomolar level. In this paper, we break this barrier/limit by introducing a sensing platform that uses a multi-length-scale electrode architecture consisting of 3D printed silver micropillars decorated with graphene nanoflakes and use it to demonstrate the detection of dopamine at a limit-of-detection of 500 attomoles. The graphene provides a high surface area at nanoscale, while micropillar array accelerates the interaction of diffusing analyte molecules with the electrode at low concentrations. The hierarchical electrode architecture introduced in this work opens the possibility of detecting biomolecules at ultralow concentrations.

B(OH)2-functionalized graphene nanoflake as a promising nanocarrier for letrozole delivery: A DFT study

We studied the capability of pristine, Al-doped and B(OH)2-functionalized graphene nanoflakes for delivery of Letrozole (LT) anticancer agent using density functional theory calculations. It was shown that LT/pristine graphene complex includes very weak physical interaction with Ead = -2.447 kcal.mol-1 which is so weak to be applied in drug delivery purposes. So, graphene nanoflake was doped by Al atom and the calculations demonstrated the LT adsorption energy was increased significantly (Ead = -33.571 kcal.mol-1). However, the LT release study showed that the adsorption energy did not change efficiently upon protonation in acidic environment (Ead = -31.857 kcal.mol-1). Finally, the LT adsorption was investigated on B(OH)2-functionalized graphene. The calculations represented that the adsorption energy was -9.607 kcal.mol-1 which can be attributed to the possible hydrogen bonding between LT molecule and B(OH)2 functional group. The adsorption energy was changed to -1.015 kcal.mol-1 during protonation process. It can be concluded that the protonation of LT/B(OH)2-functionalized graphene complex in carcinogenic cells area, separates the LT from the nanocarrier. Thus, B(OH)2-functionalized graphene nanoflakes can be considered as a promising nanocarrier candidate for LT delivery.