Studies on PEGylated and drug-loaded PAMAM dendrimers

Three methods were investigated for their suitability for the activation of poly(ethylene glycol) 2000 mono-methyl ether en route to conjugation with dendrimers, using 4-nitrophenylchloroformate as the activator. The use of acetonitrile as a solvent gave the best results. Poly(ethylene glycol) (PEG) grafted polyamidoamine (PAMAM) dendrimers were synthesized and characterized; the use of acetonitrile as a solvent gave the best result. A series of PEG conjugated PAMAM dendrimers with varying degrees of substitution of the dendrimer surface functional group by PEG were prepared. The encapsulation efficiency and the in vitro release characteristics of these PEG conjugated PAMAM dendrimers were studied. The percentage coverage of PAMAM dendrimer surface with PEG had little effect on the encapsulation efficiency but affected the release of methotrexate. IR spectra showed that many of the encapsulated methotrexate molecules were located within the cavity of the dendrimer.