Quantum and thermodynamic evaluation of C24 fullerene-based nanosensors for detection of mydayis in biomedical and drug detection applications

From a public health and forensic perspective, the detection of Mydayis (a long-acting amphetamine-based drug) is crucial due to its psychotropic effects. In this work, Density Functional Theory (DFT), Time-Dependent DFT (TD-DFT), and Quantum Theory of Atoms in Molecules (QTAIM) were employed to evaluate pristine C₂₄ fullerene and its doped derivatives (BC₂₃ and SiC₂₃) as nanosensors for Mydayis. Key electronic, thermodynamic, optical, and adsorption-based parameters were calculated, and the IR spectrum simulated using DFT showed strong agreement with experimental IR data reported in the literature, confirming the reliability of the computational approach. Among the investigated structures, pristine C24 was identified as the most effective disposable electrochemical sensor, exhibiting moderate adsorption energy (- 23.88 kcal.mol^-1), a measurable conductivity increase (2.74 × 10⁹ → 2.77 × 10⁹ A.m^-2), and significant enhancements in dipole moment (0.00 → 11.253 D) and polarizability (170.8 → 285.994 a.u.). In contrast, BC₂₃ and SiC₂₃ demonstrated exceptionally strong adsorption behavior (- 53.09 and - 54.00 kcal.mol^-1, respectively) and extremely long recovery times (8.13 × 10²⁶ and 3.80 × 10²⁷ s), establishing them as excellent high-capacity absorbers for irreversible Mydayis capture. Additionally, BC₂₃ exhibited the most pronounced colorimetric response, with a dramatic bathochromic shift from 432 to 655 nm upon Mydayis binding, confirming its role as the best disposable colorimetric sensor. These findings highlight the complementary roles of C₂₄, BC₂₃, and SiC₂₃ in the electrochemical, optical, and adsorptive detection of Mydayis and provide a robust theoretical foundation for future experimental sensor development.