Direct TLC/MALDI–MS coupling for modified polyamidoamine dendrimers analyses

• TLC separates the species present in polyamidoamine samples according to their polarity.
• TLC/MALDI allows us to attribute more easily the fragment ions as they are aligned with their precursor ions with the same Rf.
• TLC/MALDI is easy, fast and requires small quantities of material.

Polyamidoamine (PAMAM) are synthetic dendrimers which present attractive properties for the biological and biomedical fields, as they proved to be efficient drug and gene carriers. In order to increase their transfection efficiency, chemical modifications of the amino end-groups had been reported. In this work, the synthesis of the ammonia-cored G1(N) PAMAM and the consecutive chemical modification with glycine or phenylalanine amino-acids were monitored using the coupling of thin layer chromatography (TLC) with matrix–assisted laser desorption ionization–mass spectrometry (MALDI–MS). Thus, the monitoring of the PAMAM synthesis included the identification of the by-products such as defective structures of PAMAM dendrimers as well as the study of phenylalanine-grafted PAMAM oligomer distribution.

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