On the potential of the WSi₁₂ superatom as a drug carrier: a DFT study

The adsorption behaviors of 5-fluorouracil (5-Fu), 5-aminosalicylic acid (5-ASA), isoniazid (INH), 6-thioguanine (6-TG), and temozolomide (TMZ) onto the WSi₁₂ superatom have been studied using density functional theory calculations to explore its potential application in drug delivery. Our results demonstrate that 5-Fu is bound to WSi₁₂via very weak interaction with a small E_ad value of -11.62 kcal mol^-1, while the tight adsorption of TMZ greatly deforms this superatom and results in a high E_def value of 86.92 kcal mol^-1, suggesting that WSi₁₂ is not suitable to serve as a carrier for these two drugs. Fortunately, 5-ASA, INH, and 6-TG can be effectively bound to WSi₁₂via forming polar covalent bonds in the resulting 5-ASA@WSi₁₂, INH@WSi₁₂, and 6-TG@WSi₁₂ with the E_ad values of -25.71 kcal mol^-1, -19.65 kcal mol^-1, and -24.24 kcal mol^-1, respectively. As a result, the recovery time for the release of these drugs is moderate, indicating that this superatom can be regarded as a potential carrier for 5-ASA, INH, and 6-TG. Moreover, it is found that the E_ad value of 6-TG@WSi₁₂ is reduced from -24.24 to -15.29 kcal mol^-1 under weakly acidic conditions, and the drug delivery performances of WSi₁₂-extended WSi₆₍ (n = 2, 4, and 6) nanostructures are better than that of a single WSi₁₂ superatom. We hope that this study could provide a valuable reference for further experiments on using such WSi clusters as novel drug delivery carriers.