▎ 摘　　要

Using density functional theory, we study the adsorption of cysteine molecules on the monolayer, AB bilayer, and bilayer graphene with beta = 32.20 degrees, 27.79 degrees, and 5.08 degrees as twist-angles. Considering that the adsorption takes place through three sites defined by the three functional groups of cysteine, that is, amine, thiol, and carbonyl, over graphene, we find that adsorption energies are larger than kBT at room temperature, while the electronic properties of graphene structures remain unaffected. Also, we discussed the influence of the moire ' pattern on molecule adsorption by analyzing two different regions associated with AA and AB stacking. Our results show that the adsorption energies depend on the staking region, therefore, on the twist-angle, confirming that the latter parameter can be used to tune cysteine adsorption. Besides, we discussed the feasibility of twisted-bilayer graphene as enantioselector substrate, comparing the results of L- and D-cysteine enantiomers.