Single-cell measurements of polyamidoamine dendrimer binding.
The binding of fluorescein-labeled polyamidoamine dendritic polymers (dendrimers) to the surface of individual fibroblast cells has been quantitatively measured using confocal fluorescence microscopy. Because the binding of these polymers is not strong, significant fluorescence from polymers in solution complicates the measurement, even using confocal optics. To overcome this difficulty, we have developed a new method employing a cell-entrapped marker dye to determine the extracellular volume in each voxel. This allows for a correct subtraction of fluorescence due to polymers in solution. We have found that, as expected, the larger dendrimers bound more tightly than the smaller generations, which may partially account for their increased efficacy in DNA transfection applications. The binding varied significantly from cell to cell, and an analysis of the cell surface area showed that this variability was not caused simply by variations in cell size.
Lai
Johnathan C
JC
Department of Biomedical Engineering, Columbia University of the City of New York, New York, USA.
Yuan
Calin
C
Thomas
James L
JL
D000818:Animals; D001672:Biocompatible Materials; D015415:Biomarkers; D002448:Cell Adhesion; D002460:Cell Line; D048429:Cell Size; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism*; D005452:Fluoresceins / Q000493:pharmacokinetics*; D005456:Fluorescent Dyes / Q000493:pharmacokinetics*; D051379:Mice; D018613:Microscopy, Confocal / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D008954:Models, Biological; D011073:Polyamines / Q000493:pharmacokinetics*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D001672:Biocompatible Materials; D015415:Biomarkers; D005452:Fluoresceins; D005456:Fluorescent Dyes; D011073:Polyamines; C018506:diacetylfluorescein