title: Use of near-infrared luminescent gold nanoclusters for detection of macrophages.
abstract: We determined the effect of aggregation and coating thickness of gold on the luminescence of nanoparticles engulfed by macrophages and in gelatin phantoms. Thin gold-coated iron oxide nanoclusters (nanoroses) have been developed to target macrophages to provide contrast enhancement for near-infrared optical imaging applications. We compare the brightness of nanoroses luminescent emissions in response to 635 nm laser excitation to other nanoparticles including nanoshells, nanorods, and Cy5 conjugated iron oxide nanoparticles. Luminescent properties of all these nanoparticles were investigated in monomeric and aggregated form in gelatin phantoms and primary macrophage cell cultures using confocal microscopy. Aggregation of the gold nanoparticles increased luminescence emission and correlated with increased surface mass of gold per nanoparticle (nanoshells 37 ± 14.30 × 10(-3) brightness with 1.23 × 10(-4) wt of gold (g)/nanoparticle versus original nanorose 1.45 ± 0.37 × 10(-3) with 2.10 × 10(-16) wt of gold/nanoparticle, p<0.05). Nanoshells showed greater luminescent intensity than original nanoroses or Cy5 conjugated iron oxide nanoparticles when compared as nanoparticles per macrophage (38 ± 10 versus 11 ± 2.8 versus 17 ± 6.5, p<0.05, respectively, ANOVA), but showed relatively poor macrophage uptake (1025 ± 128 versus 7549 ± 236 versus 96,000 nanoparticles/cell, p<0.05, student t-test nanoshells versus nanoroses). Enhancement of gold fluorescent emissions by nanoparticles can be achieved by reducing the thickness of the gold coating, by clustering the gold on the surface of the nanoparticles (nanoshells), and by clustering the gold nanoparticles themselves.
authors.affiliation: University of Texas Health Science, Center at San Antonio, Department of Medicine, 7703 Floyd Curl Drive, San Antonio, Texas 78229, USA.
authors.forename: Veronika
authors.initials: V
authors.lastname: Sapozhnikova
authors.forename: Brian
authors.initials: B
authors.lastname: Willsey
authors.forename: Reto
authors.initials: R
authors.lastname: Asmis
authors.forename: Tianyi
authors.initials: T
authors.lastname: Wang
authors.forename: James Travis
authors.initials: JT
authors.lastname: Jenkins
authors.forename: Jacob
authors.initials: J
authors.lastname: Mancuso
authors.forename: Li Leo
authors.initials: LL
authors.lastname: Ma
authors.forename: Roman
authors.initials: R
authors.lastname: Kuranov
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Milner
authors.forename: Keith
authors.initials: K
authors.lastname: Johnston
authors.forename: Marc D
authors.initials: MD
authors.lastname: Feldman
mesh_terms: D000818:Animals; D058948:Cell Tracking / Q000379:methods*; D002478:Cells, Cultured; D006046:Gold; D007259:Infrared Rays; D008264:Macrophages / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal / Q000379:methods*; D053758:Nanoparticles; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D006046:Gold