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Surface functionalization of gold nanoparticles using hetero-bifunctional poly(ethylene glycol) spacer for intracellular tracking and delivery

Authors Dinesh Shenoy, Wei Fu, Jane Li, Curtis Crasto, Graham Jones, Charles DiMarzio, Srinivas Sridhar, Mansoor Amiji

Published 15 March 2006 Volume 2006:1(1) Pages 51—57

Dinesh Shenoy1, Wei Fu2, Jane Li3, Curtis Crasto3, Graham Jones3, Charles DiMarzio4, Srinivas Sridhar2, Mansoor Amiji1

Departments of 1Pharmaceutical, Sciences, 2Physics, 3Chemistry and Chemical Biology, 4Electrical and Computer Engineering, and the Nanomedicine Consortium, Northeastern University, Boston, MA, USA 

Abstract: For the development of surface-functionalized gold nanoparticles as cellular probes and delivery agents, we have synthesized hetero-bifunctional poly(ethylene glycol) (PEG, MW 1500) having a thiol group on one terminus and a reactive functional group on the other for use as a flexible spacer. Coumarin, a model fluorescent dye, was conjugated to one end of the PEG spacer and gold nanoparticles were modified with coumarin-PEG-thiol. Surface attachment of coumarin through the PEG spacer decreased the fluorescence quenching effect of gold nanoparticles. The results of cellular cytotoxicity and fluorescence confocal analyses showed that the PEG spacer-modified nanoparticles were essentially non-toxic and could be efficiently internalized in the cells within 1 hour of incubation. Intracellular particle tracking using a Keck 3-D Fusion Microscope System showed that the functionalized gold nanoparticles were rapidly internalized in the cells and localized in the peri-nuclear region. Using the PEG spacer, the gold nano-platform can be conjugated with a variety of biologically relevant ligands such as fluorescent dyes, antibodies, etc in order to target, probe, and induce a stimulus at the target site.

Keywords: gold nanoparticles, hetero-bifunctional poly(ethylene glycol) spacer, surface functionalization, cellular trafficking, cytotoxicity