Calculation of Molecular Masses.

The molar mass of PMLA has been routinely measured by SEC-HPLC in phosphate buffered saline pH 7.0 using polystyrenesulfonate as molecular mass standards. The standards resemble the structure of PMLA only remotely, but reflect the polyanionic character at pH 7.0, and otherwise fail when comparing PMLA and chemical derivatives which differ in number and kind of structural modifications. This is mirrored by the polymer hydrodynamic radius after ligand substitutions that could not be standardized.¹⁶

The molecular mass of nanoconjugates was calculated on the basis of their constituents’ masses and stoichiometry. For example, the molar mass of PMLA/LLL(40%)/MEA(l0%) is composed of (l) the molar mass of PMLA at 50,000 g/mol corresponding to the number of 50,000/116 = 431 (100%) malyl residues. (2) The molar mass of tripeptides LLL (40%) attached to 40% malyl residues corresponds to 0.40 X 431 X 357.5 = 61,633 g/mol. (3) The molar mass of 2-mercapto ethylamine (MEA, 10%) attached to 10% malyl residues corresponds to 0.10 × 431 × 77 = 3319 g/mol. The resulting molar mass of the conjugate is 50,000 g/mol + 61,633 g/mol + 3319 g/mol = 114,952 g/mol. After correction for water liberated by the condensation corresponding to 0.5 × 431 × 16 = 3448 g/mol, the molar mass of P/LLL/MEA is calculated as 111,504 g/mol.