In Vivo Volumetric Photoacoustic Molecular Angiography and Therapeutic Monitoring with Targeted Plasmonic Nanostars

Abstract

Photoacoustic (PA) imaging promises deeper tissue penetration while maintaining rich optical contrast as compared to other high resolution optical imaging techniques. In this report, a near-infrared pulse laser serves as the excitation source, and 128 ultrasonic transducers are spirally distributed on a hemispherical surface to receive PA signals for three-dimensional (3D) image reconstruction. With these attributes, the unique modality produces an isotropic and homogeneous spatial resolution (∼200 μm) with penetration depth of centimeters. Cyclic Arg-Gly-Asp (RGD) peptides conjugated plasmonic gold nanostars (RGD-GNS) are designed to specifically target over-expressed integrin α(v)β₃ on tumor neovasculature, enabling highly sensitive angiography and photothermal therapy (PTT). After the administration of RGD-GNS, tumor angiogenesis is clearly imaged with enhanced contrast, and the growth of tumor is effectively inhibited by PTT after laser irradiation. This study suggest that the PA angiography with plasmonic RGD-GNS can be applied as a triple functional platform for tumor diagnosis, PTT, and treatment monitoring. This PA technique offers deeper imaging depth with homogeneous resolution over existing optical imaging techniques for early diagnosis of tumor angiogenesis as well as on-the-spot nanotherapeutic evaluation.

Gold nanoprisms as a hybrid in vivo cancer theranostic platform for in situ photoacoustic imaging, angiography, and localized hyperthermia

“…S8 in the ESM). Moreover, the thermal effect of RGDconjugated PEGylated NPs could be exploited to treat cancer-diseased cells [23].…”

All-optical photoacoustic projection imaging

“…We would like to point out that the ability to monitor large volumes by acquiring projection images at a high frame rate would be outstanding compared to other approaches for small animal imaging using piezoelectric transducer arrays. To acquire sufficiently dense photoacoustic data for high-resolution volumetric imaging of small animals or the human breast with hemispherical [14,16] or arcshaped [11,12] piezoelectric transducer arrays, multiple measurements at different rotational angels are necessary. The required time for such measurements is in the range of several tens of seconds to minutes.…”

“…The transducers can be arranged in various geometries. E.g., linear [10], arc-shaped [11,12], (hemi-)spherical [13][14][15][16], planar [17,18], or circular arrangements [19,20] have been demonstrated. In general, a large number of detector elements is required in order to image a volume at high resolution.…”

Photoacoustic Imaging: A Novel Tool for Detecting Carotid Artery Thrombosis in Mice

“…A few studies have used PAI to investigate atherosclerosis plaques [17,18] as well as to detect breast tumors [19] and melanoma [20]. Thus, PAI not only resolves anatomical contrasts but can also visualize hemoglobin [6,21,22,23], melanin [20], lipids [17,18], and a wide variety of optical agents [24,25,26,27,28]. It can be used to visualize molecular tissue changes and anatomical tissue changes, such as those caused by stenosis.…”