Label-Free Visualization and Tracking of Gold Nanoparticles in Vasculature Using Multiphoton Luminescence.

Sean Burkitt,Cristina Zavaleta,Scott Fraser,Mana Mehraein,Jos Campbell,Ramunas K Stanciauskas

doi:10.3390/nano10112239

Abstract

Gold nanoparticles continue to generate interest for use in several biomedical applications. Recently, researchers have been focusing on exploiting their dual diagnostic/therapeutic theranostic capabilities. Before clinical translation can occur, regulatory agencies will require a greater understanding of their biodistribution and safety profiles post administration. Previously, the real-time identification and tracking of gold nanoparticles in free-flowing vasculature had not been possible without extrinsic labels such as fluorophores. Here, we present a label-free imaging approach to examine gold nanoparticle (AuNP) activity within the vasculature by utilizing multiphoton intravital microscopy. This method employs a commercially available multiphoton microscopy system to visualize the intrinsic luminescent signal produced by a multiphoton absorption-induced luminescence effect observed in single gold nanoparticles at frame rates necessary for capturing real-time blood flow. This is the first demonstration of visualizing unlabeled gold nanoparticles in an unperturbed vascular environment with frame rates fast enough to achieve particle tracking. Nanoparticle blood concentration curves were also evaluated by the tracking of gold nanoparticle flow in vasculature and verified against known pre-injection concentrations. Half-lives of these gold nanoparticle injections ranged between 67 and 140 s. This label-free imaging approach could provide important structural and functional information in real time to aid in the development and effective analysis of new metallic nanoparticles for various clinical applications in an unperturbed environment, while providing further insight into their complex uptake and clearance pathways.

Highlights

Nanoparticles have great potential for several biomedical applications and are currently being used as drug delivery vehicles, treatment response monitors, and in early-stage disease diagnostics [1,2,3,4]
Gold luminescent production was first observed in gold–silica nanoparticles containing a Raman active layer previously used for surface-enhanced Raman spectroscopy (SERS) imaging by our group (Figure 1) [6,34]
We evaluated each of the following on slides: (1) 60 nm gold nanoparticles, (2) 130 nm pure silica nanoparticles, and (3) 126 nm gold-silica Raman active nanoparticles (Figure 1A)

Summary

Introduction

Nanoparticles have great potential for several biomedical applications and are currently being used as drug delivery vehicles, treatment response monitors, and in early-stage disease diagnostics [1,2,3,4]. Gold nanoparticles have been used as multimodal imaging agents with applications in computed tomography (CT), photoacoustic and Raman imaging [6,7,8,9]. Gold nanoparticles are increasingly utilized as “theranostic” agents, combining therapeutic uses such as thermal ablation with other diagnostic imaging capabilities [10,11]. Other ongoing clinical trials include the thermal ablation of head and neck tumors, lung nodules, and prostate cancer using gold–silica nanoparticles [13,14,15,16]. They have been recently FDA-approved for the treatment of acne [17]. Gold nanoparticles are at an inflection point for clinical translation; this transition will require a more thorough assessment of their in vivo distribution and fate

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