Possible kinetic Equilibria of 5-Fluorouracil Drug with Anionic and Cationic Micelles

Initially, anionic (SDS) and cationic (TBAB) micelles were prepared with a suitable concentration (0.1 mM) in potassium phosphate buffer at physiological conditions (pH=7.4 and T=37◦C). The followed method of micelles molecules was distinguished by fixed its molecules as a monomer, unclouded and clarity solutions as well as agreement with an ideal linearity of Beer-Lambert law. Then, the spectral checkup of 5-FU drug (0.1 mM; with =0.673 at λ=266 nm) and the micelles solutions (as blank solution; without any interferences) were achieved in a phosphate buffer at physiological conditions. This matter was encouraged on complete assessment of the equilibrium state between chemotherapy compound (5-FU) with micelles, which it can be accompanied into formation processes of molecular complexes. The produced spectral lines of molecular complexes were followed as first order interactions for SDS (at 268 nm; k∗=7.60× 10–3 min–1; t1/2= 91.20 min) and TBAB micelles (at 267 nm; k∗=17×10–3 min–1; t1/2= 40.76 min). mathematically, the same obtained results were treated as a reversible equilibrium from first order interaction; with same physicochemical parameters for TBAB micelles (with; Keq=17.72). But, the opposite properties of SDS micelles were extracted (k1=15.17×10–3; k−1= 1.22×10–3 min–1; τ∗= 42.25 min; Keq=12.38) as result of complicated interactions involved the relaxation equilibrium processes. The molecular complexes interactions (5-FU drug and micelles) were occurred spontaneously, with free energies favourable for van der Waals forces or hydrogen bonding (Δ G0<10 kJ/mol).