A high concentration of trimethylamine (TMA) in the body can be converted to trimethylamine N-oxide (TMAO), which is a well-known proatherogenic substance capable of accelerating atherosclerosis disease in humans. Hence, there is a pressing need for the development of fast, accurate and reliable nanomaterials for the detection of TMA. In this study, the interaction of TMA with aluminium nitride nanotube (AlNNT) and gallium-doped aluminium nitride nanotube (AlNGaNT) was investigated using density functional theory at the M06-2X, B3LYP, ${\omega}$B97XD at 6-311G(d)/6- 31G(d) levels of theory. The results of the interaction energy between AlNGaNT and TMA for the 6-31G(d) increased remarkable in the order of M06-2X: -1.57 < B3LYP-D3:1.58 < ${\omega}$B97XD: 1.89 kcal mol$^{-1}$, while the 6-311G(d) showed higher interaction energy in the order of B3LYP-D3: -1.96 < M06-2X: -1.99 < ${\omega}$B97XD: -2.03 kcal mol$^{-1}$. Generally, the interaction of TMA with AlNNT and AlNGaNT increases the global reactivity parameter. From topological, a strong interaction was observed from -0.010 to -0.050 a.u. for sign${\lambda}_2$(r)${\rho}$(r) function and 0.000 to 0.00 to 0.400 for aRDG in TMA/AlNGaNT, where at sign${\lambda}_2$(r)${\rho}$(r) more scattered plot was observed between -0.050 to -0.020 a.u. While the small scattered plot was observed for TMA/AlNGaNT at 0.00 to -0.010 a.u. for sign${\lambda}_2$(r)${\rho}$(r) and aRDG of 0.00 to 0.400. Therefore, it was proposed that an electrostatic interaction is the mechanism between TMA and the AlNNC, and the strength of the interaction increase with the addition of Ga-atom as in AlNGaNT.