engleski

Computational study on the binding of L-dopa, dopamine and oxidised derivatives to gold nanoparticles

Nano-drug delivery systems for treatment of Parkinson's disease are being designed to overcome present therapeutical challenges. L-dopa and dopamine attached to the surface of gold nanoparticles (AuNPs) may be efficiently delivered through the blood-brain barrier. However, the preparation of L-dopa and dopamine coated AuNPs by the traditional reduction method may lead to the creation of oxidation products, which will exacerbate oxidative stress in the body. For the development of L-dopa and dopamine nanocarriers, it is important to ascertain whether toxic byproducts might be present on the AuNP surface. Here, the surface events and interaction of AuNPs with L-dopa, dopamine and their oxidised derivatives are studied by employing a computational approach. Quantum chemical study using the Gaussian software yielded the optimized complexes of studied species with Aun (n=2, 4, 6) clusters at the M06L/LANL2DZ level of theory. It was found that the complexes with oxidised derivatives were more stable compared to complexes with L-dopa and dopamine. The binding behaviour and free energies were calculated by classical molecular dynamics. Although all studied molecules bind to the Au surface spontaneously, the free binding energies of oxidised derivatives are lower, confirming their higher affinity to Au. Thus, under the conditions of carrier AuNP preparation (where L-dopa or dopamine are present together with oxidation products), the oxidised derivatives are expected to bind in significant proportion. This study highlights the need to carefully characterize the binding events at the surface of potential drug nanocarriers, and demonstrates the usefulness of the in silico approach in such endeavours.

L-dopa, dopamine, oxidised derivatives, gold nanoparticles, quantum chemistry, molecular dynamics

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