Carbon Nanotubes as Biosensors for Releasing Conjugated Bisphosphonates–Metal Ions in Bone Tissue: Targeted Drug Delivery through the DFT Method

Abstract

Bisphosphonate (BP) agents have attracted much attention for their precise therapy in some skeletal maladies demonstrated by enhancing osteoclast-mediated bone resorption. In this work, the use of CAM-B3LYP/6-311+G(d,p)/LANL2DZ to estimate the susceptibility of single-walled carbon nanotube (SWCNT) for adsorbing alendronate, ibandronate, neridronate, and pamidronate chelated to two metal cations of 2Mg2+, 2Ca2+, and 2Sr2+ through nuclear magnetic resonance and thermodynamic parameters has been accomplished. For most biological medications, oral bioavailability is too low to reach a therapeutic level, and advanced delivery systems such as formulations including permeation enhancers or enzyme inhibitors, lipid-based nanocarriers, and microneedles will likely increase the oral bioavailability of these medications properly. Therefore, the measurements have described that the eventuality of using SWCNT and BP agents becomes the norm in metal chelating of the drug delivery system, which has been selected through (alendronate, ibandronate, neridronate, pamidronate) → 2X (X = Mg2+/Ca2+/Sr2+) complexes. The NMR results of chelated alendronate, ibandronate, neridronate, and pamidronate complexes adsorbed onto (5,5) armchair SWCNT have remarked the location of active sites of tagged nitrogen (N), phosphorus (S), oxygen (O), and metal cations of magnesium (Mg2+), calcium (Ca2+), and strontium (Sr2+) in these molecules which replace the movement of the charge electron transfer in polar bisphosphonates (BPs) toward (5,5) armchair carbon nanotube (CNT). The thermodynamic results have exhibited that the substitution of 2Ca2+ cation by 2Sr2+ cation in the compound of the bioactive glasses can be efficient for treating vertebral complex fractures. However, the most fluctuation in the Gibbs free energy for BPs → 2Sr2+ has been observed at 300 K. This manuscript aimed to show that (5,5) armchair SWCNT can easily penetrate in the bone cells, delivering chelated BP–cations directly to the bone tissue. Drug delivery systems can improve the pharmacological profile, therapeutic profile, and efficacy of BP drugs and lower the occurrence of off-targets.