Photoacoustic imaging of cancer cells with glycol-chitosan-coated gold nanoparticles as contrast agents.

In-Cheol Sun,Kwangmeyung Kim,Cheol-Hee Ahn,Stanislav Emelianov

doi:10.1117/1.jbo.24.12.121903

Abstract

.Utility of glycol-chitosan-coated gold nanoparticles (GC-AuNPs) as a photoacoustic contrast agent for cancer cell imaging was demonstrated. Through the synergistic effect of glycol chitosan and gold nanoparticles, GC-AuNPs showed cellular uptake in breast cancer cells and resulted in strong photoacoustic signals in tissue-mimicking cell phantoms. The performance of GC-AuNPs as contrast agents was established with photoacoustic imaging and confirmed with dark-field microscopy. The cell phantoms displayed strong photoacoustic signals if cells were incubated more than 3 h with GC-AuNPs, compared with PEG-AuNPs that showed no photoacoustic signal increase. The enhanced photoacoustic signals originated from the plasmon coupling effect of GC-AuNPs after the cellular uptake in cancer cells. Importantly, photoacoustic imaging of cancer cells was achieved with GC-AuNPs—contrast agents that did not require antibodies or complex surface modification. The endocytosis of GC-AuNPs was also confirmed with dark-field microscopy. The results show that GC-AuNPs have potential as a photoacoustic contrast agent for cellular imaging including tumor tissue imaging.

Highlights

Ultrasound imaging is a safe and cost-effective imaging modality capable of high spatial and temporal resolutions, and penetration depth
Gold nanoparticles (AuNPs) are promising exogenous contrast agents because they have unique optical properties that are desirable for photoacoustic imaging.[8]
We have demonstrated an application of GC-AuNPs as a photoacoustic contrast agent for cancer cell imaging

Summary

Introduction

Ultrasound imaging is a safe and cost-effective imaging modality capable of high spatial and temporal resolutions, and penetration depth. Photoacoustic imaging provides high-contrast images by using endogenous or exogenous chromophores with distinct optical absorption property.[5,6,7] If the exogenous contrast agent is designed to absorb pulsed laser light of specific wavelengths that is away from the optical absorption of endogenous tissue chromophores, generated photoacoustic signals have minimal overlap with background tissue signals.[8]. Gold nanoparticles (AuNPs) are promising exogenous contrast agents because they have unique optical properties that are desirable for photoacoustic imaging.[8] Upon exposure to laser irradiation, AuNPs absorb light through a surface plasmon resonance (SPR) phenomenon. The absorption of AuNPs is the highest if the frequency of incident light is similar to the resonance frequency of surface plasmon This resonance phenomenon is called SPR, which results in the high absorption peak of AuNPs in the UV-vis-NIR spectrum

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Discussion

Conclusion