Characterization and In Vivo Biodistribution Studies with Poly(Ethylene Glycol)-Modified Thiolated Gelatin Nanoparticles
S. Kommareddy and M.M. Amiji
Northeastern University, US
thiolation, crosslinked, nanoparticles
Objective: The objective of the current study was to synthesize and modify thiolated gelatin nanoparticles with PEG chains, characterize, and evaluate their long circulating and tumor targeting potentials in vivo in a human breast cancer xenograft model.
Methods: The thiolated gelatin was synthesized by covalent modification of the amine groups of gelatin with 2-iminothiolane. The nanoparticles were prepared by desolvation and modified with PEG. The non-crosslinked and crosslinked nanoparticulate systems were characterized and the release profiles of the fluorescein isothiocyanate (FITC)-dextran encapsulated nanoparticles in phosphate buffered saline (PBS) containing glutathione (0-5mM GSH) were compared. Qualitative and quantitative analysis of transfection in NIH3T3 cells by the nanoparticles carrying plasmid DNA was done by fluorescence microscopy and fluorescence–activated cell sorting (FACS). The biodistribution and the long circulating potential of the PEG-modified thiolated gelatin nanoparticles was evaluated by injecting the 111In-labeled nanoparticles into tumor bearing nude mice.
Results: The degree of thiolation ranged from 0 to 43.71mMoles of sulfhydryl groups per gram of gelatin. The nanoparticles had a size of 150-250 nm and the release profiles show that the release of FITC-dextran from the non-crosslinked nanoparticles was significantly greater than from the crosslinked nanoparticles both in the presence and absence of GSH. The presence of GSH was found to enhance the release by about 40%. The crosslinking did not have any significant effect on nanoparticle uptake however, the quantitative analysis by FACS shows that the crosslinked nanoparticles of SHGel-20 had greater transfection efficiency when compared to SHGel-40 and gelatin. The in vivo biodistribution profile of SHGel-20 nanoparticles was compared to that of PEG-SHGel-20 nanoparticles.
Conclusions: The results of this study show that the thiolated gelatin nanoparticles have sensitivity towards highly reducing environment wherein the disulfide bonds are reduced to trigger-release the payload. Upon modification with PEG the nanoparticles have longer circulation potential and hence can be used to passively target solid tumors in vivo.
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Nanotech 2006 Conference Program Abstract