Multilayer Model of Gold Nanoparticles (AuNPs) and Its Application in the Classical Molecular Dynamics Simulation of Citrate-Capped AuNPs.

Studies on the interaction between gold nanoparticles (AuNPs) and functional proteins have been useful in developing diagnostic and therapeutic agents. Such studies require a realistic computational model of AuNPs for successful molecular design works. This study offers a new multilayer model of AuNPs to address the inconsistency between its molecular mechanics' interpretation and AuNP's plasmonic nature. We performed partial charge quantum calculation of AuNPs using Au13 and Au55 models. The result showed that it has partial negative charges on the surface and partial positive charges on the inner part, indicating that the AuNP model should be composed of multiatom types. We tested the partial charge parameters of these gold (Au) atoms in classical molecular dynamics simulation (CMD) of AuNPs. The result showed that our parameters performed better in simulating the adsorption of Na+ and dicarboxy acetone in terms of consistency with surface charge density than the zero charges Au in the interface force field (IFF). We proposed that the multiple-charged AuNP model can be developed further into a simpler four-atom type of Au in a larger AuNP size.

Estrogen receptor targeting with genistein radiolabeled Technetium-99m as radiotracer of breast cancer: Its optimization, characterization, and predicting stability constants by DFT calculation.

Objective: Genistein is an isoflavone molecule with a high affinity for estrogen receptors (ER), which could lead to the mechanism of selective estrogen receptor modulators (SERMs) in breast cancer. Genistein labeling with technetium-99m can be a new promising strategy for diagnostic breast cancer. In this research, we evaluate the physicochemical characteristics of the [99mTc]Tc-genistein complex and describe the optimal labeling method parameters. We also calculated density functional theory to study the stability constants to support complex formation analysis (DFT). Methods: The genistein was directly labeled with 99mTc, and its stability as well as its potential for usage as a radiotracer were all investigated. DFT calculations with thermodynamic cycles to determine chemical coordination models and calculate thermodynamic constants of complex more accurately. Results: The radiochemical purity of [99mTc]Tc-genistein showed a high yield of 93.25% ± 0.30% and had good physicochemical properties. The stability of the Tc(IV)-genistein complex was confirmed by DFT calculations at a value of 99.0822. Conclusions: As a result, [99mTc]Tc-genistein could be a potential radiotracer kit for SPECT imaging of breast cancer.