Design and synthesis of single-nanoparticle opticalbiosensorsfor imaging andcharacterizationof single receptor molecules on single living cells

Abstract Click to copy section link Section link copied! At the cellular level, a small number of protein molecules (receptors) can induce significant cellular responses, emphasizing the importance of molecular detection of trace amounts of protein on single living cells. In this study, we designed and synthesized silver nanoparticle biosensors (AgMMUA−IgG) by functionalizing 11.6 ± 3.5-nm Ag nanoparticles with a mixed monolayer of 11-mercaptoundecanoic acid (MUA) and 6-mercapto-1-hexanol (1:3 mole ratio) and covalently conjugating IgG with MUA on the nanoparticle surface. We found that the nanoparticle biosensors preserve their biological activity and photostability and can be utilized to quantitatively detect individual receptor molecules (T-ZZ), map the distribution of receptors (0.21−0.37 molecule/μm 2 ), and measure their binding affinity and kinetics at concentrations below their dissociation constant on single living cells in real time over hours.

The dynamic range of detection is 0−50 molecules per cell. We also found that the binding rate (2−27 molecules/min) is highly dependent upon the coverage of receptors on living cells and their ligand concentration. The binding association and dissociation rate constants and affinity constant are k 1 = (9.0 ± 2.6) × 10 3 M -1 s -1 , k - 1 = (3.0 ± 0.4) × 10 - 4 s -1 , and K B = (4.3 ± 1.1) × 10 7 M -1 , respectively. ACS Publications Copyright © 2007 American Chemical Society Subjects what are subjects Article subjects are automatically applied from the ACS Subject Taxonomy and describe the scientific concepts and themes of the article.

Metal nanoparticles Molecules Nanoparticles Receptors Sensors