Identification of second harmonic optical effects from vaccine coated gold microparticles

TY - JOUR

T1 - Identification of second harmonic optical effects from vaccine coated gold microparticles

AU - Jumah, N A

AU - Ameer-Beg, S M

AU - White, N S

AU - Prasad, K V R

AU - Bellhouse, B J

PY - 2004/8/21

Y1 - 2004/8/21

N2 - This study investigates the optical effects observed from uncoated and protein vaccine coated gold microparticles while imaging with two-photon excitation in the Mie scattering regime. When observed with time correlated single photon counting fluorescence lifetime microscopy, the emission from the gold microparticles appeared as an intense instrument-limited temporal response. The intensity of the emission showed a second-order dependence on the laser power and frequency doubling of the emitted light was observed for fundamental light between 890 and 970 nm. The optical effect was attributed to two-photon induced second harmonic generation. The vaccine coated gold microparticles had a much weaker second harmonic signal than the uncoated gold microparticles. Chemical analysis of the surface of the gold microparticles revealed that the vaccine coating decreases the surface charge thereby diminishing the observed second harmonic signal. These optical properties can be exploited to identify both the location of the protein vaccine coating as well as the gold microparticles in vitro and potentially to investigate the vaccine delivery kinetics in vivo

AB - This study investigates the optical effects observed from uncoated and protein vaccine coated gold microparticles while imaging with two-photon excitation in the Mie scattering regime. When observed with time correlated single photon counting fluorescence lifetime microscopy, the emission from the gold microparticles appeared as an intense instrument-limited temporal response. The intensity of the emission showed a second-order dependence on the laser power and frequency doubling of the emitted light was observed for fundamental light between 890 and 970 nm. The optical effect was attributed to two-photon induced second harmonic generation. The vaccine coated gold microparticles had a much weaker second harmonic signal than the uncoated gold microparticles. Chemical analysis of the surface of the gold microparticles revealed that the vaccine coating decreases the surface charge thereby diminishing the observed second harmonic signal. These optical properties can be exploited to identify both the location of the protein vaccine coating as well as the gold microparticles in vitro and potentially to investigate the vaccine delivery kinetics in vivo

U2 - 10.1088/0031-9155/49/16/008

DO - 10.1088/0031-9155/49/16/008

M3 - Article

VL - 49

SP - 3603

EP - 3612

JO - Physics in Medicine and Biology

JF - Physics in Medicine and Biology

IS - 16

ER -