Synthesis and characterization of a colloidal novel folic acid–β-cyclodextrin conjugate for targeted drug delivery

A novel folic acid–β-cyclodextrin (β-CD) conjugate was synthesized and preliminarily characterized by 1H NMR, ESI-MS, and MALDI-MS. 1H NMR shows the presence of α- and γ-conjugates which are generated by β-CD linkage in turn with both carboxylic functions of folic acid. Moreover ROESY evidences supramolecular interactions between the benzene ring of the folic acid and the β-CD cavity. DOSY suggests that ethylenediamine derived β-CD–folic acid forms a colloidal dispersion difficult to purify from free folic acid. An analysis of self-diffusion coefficient (Ds) of the three species (α-, γ-conjugates, and free folic acid) and relaxation times (T1 and T2) is reported to tentatively explain the colloidal behaviour of the new species in an aqueous solution.