Nowadays, scientists are working on creating better drug delivery systems. We got inspired by the discovery of a modern kind of nanoparticles (Phys. Chem. Chem. Phys., 21 (2019) 15541). These particles, called heteroborospherenes, were created by adding four carbon atoms to a B364- cluster (C4B32). Both the regular and lithium-doped versions of C4B32 (Li @C4B32) could be useful in delivering drugs. This study explores how nanoclusters, such as C4B32 and Li@C4B32, interact with a cancer drug called carmustine with a method called density functional theory. This study found that adding a Li atom to the C4B32 nanocluster greatly improved its ability to attract the carmustine drug. Our UV–visible results reveal that when the drug combines with nanoclusters, the electronic spectra shift towards longer wavelengths (lower energies), showing a redshift. It was found that carmustine /Li@C4B32 has strong chemical reactivity and it is important for the drug to attach to the target site effectively. This study used atoms in Molecule analysis to better understand how the analyzed systems interact with the carmustine. The research results demonstrate how carmustine and Li@C4B32 bond through electrostatic features. Hence, the study showed that Li@C4B32 could be a good way to deliver the carmustine drug.