Peptide-Conjugated Ultrasmall Gold Nanoparticles (2 nm) for Selective Protein Targeting

Ultrasmall gold nanoparticles with a metallic core diameter of 2 nm were surface-conjugated peptides that selectively target epitopes on the surface WW domain model protein hPin1 (hPin1-WW). The binding to was accomplished via thiol group terminal cysteine. particles analyzed by NMR spectroscopy, high-resolution transmission electron microscopy, and differential centrifugal sedimentation. loading determined conjugating FAM-labeled peptide, followed UV–vis quantitative 1H showing about 150 peptide molecules conjugated each nanoparticle. interaction between peptide-decorated hPin1-WW probed 1H–15N-HSQC titration, fluorescence polarization spectroscopy (FP), isothermal titration calorimetry (ITC). showed similar (KD = 10–20 μM) compared dissolved 10–30 μM). Small-angle X-ray scattering (SAXS) well dispersed did not agglomerate after addition (no cross-linking protein). Each nanoparticle able bind 20 molecules. An unspecific excluded attachment nonbinding surface. uptake cells studied confocal laser scanning microscopy. peptide-functionalized penetrated cell membrane located in cytosol. In contrast, cross membrane. Peptide-functionalized are promising agents proteins inside cells.