Tumor cell imaging using the intrinsic emission from PAMAM dendrimer: a case study with HeLa cells.

HeLa 229 cells were treated with methotrexate (MTX) and doxorubicin (DOX), utilizing fourth generation (G4), amine terminated poly(amidoamine) {PAMAM} dendrimer as the drug carrier. In vitro kinetic studies of the release of both MTX and DOX in presence and absence of G4, amine terminated PAMAM dendrimers suggest that controlled drug release can be achieved in presence of the dendrimers. The cytotoxicity studies indicated improved cell death by dendrimer-drug combination, compared to the control experiments with dendrimer or drug alone at identical experimental conditions. Furthermore, HeLa 229 cells were imaged for the first time utilizing the intrinsic emission from the PAMAM dendrimers and drugs, without incorporating any conventional fluorophores. Experimental results collectively suggest that the decreased rate of drug efflux in presence of relatively large sized PAMAM dendrimers generates high local concentration of the dendrimer-drug combination inside the cell, which renders an easy way to image cell lines utilizing the intrinsic emission properties of PAMAM dendrimer and encapsulated drug molecule.