Poly(ethylene glycol)-based multidentate oligomers for biocompatible semiconductor and gold nanocrystals.
We have developed a new set of multifunctional multidentate OligoPEG ligands, each containing a central oligomer on which were laterally grafted several short poly(ethylene glycol) (PEG) moieties appended with either thioctic acid (TA) or terminally reactive groups. Reduction of the TAs (e.g., in the presence of NaBH(4)) provides dihydrolipoic acid (DHLA)-appended oligomers. Here the insertion of PEG segments in the ligand structure promotes water solubility and reduces nonspecific interactions, while TA and DHLA groups provide multidentate anchoring onto Au nanoparticles (AuNPs) and ZnS-overcoated semiconductor quantum dots (QDs), respectively. The synthetic route involves simple coupling chemistry using N,N-dicylohexylcarbodiimide (DCC). Water-soluble QDs and AuNPs capped with these ligands were prepared via cap exchange. As prepared, the nanocrystals dispersions were aggregation-free, homogeneous, and stable for extended periods of time over pH ranging from 2 to 14 and in the presence of excess electrolyte (2 M NaCl). The new OligoPEG ligands also allow easy integration of tunable functional and reactive groups within their structures (e.g., azide or amine), which imparts surface functionalities to the nanocrystals and opens up the possibility of bioconjugation with specific biological molecules. The improved colloidal stability combined with reactivity offer the possibility of using the nanocrystals as biological probes in an array of complex and biologically relevant media.
Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, Florida 32306, United States.
Goutam
G
Palui
Hyon Bin
HB
Na
Hedi
H
Mattoussi
D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D045663:Quantum Dots; D012666:Semiconductors; D012995:Solubility; D013440:Sulfides / Q000737:chemistry*; D008063:Thioctic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D017967:Zinc Compounds / Q000737:chemistry*
D001672:Biocompatible Materials; D008024:Ligands; D013440:Sulfides; D017967:Zinc Compounds; D011092:Polyethylene Glycols; D008063:Thioctic Acid; D006046:Gold; C015144:dihydrolipoic acid; C031238:zinc sulfide