2 research outputs found
DataSheet1_Photoacoustic signal enhancement in dual-contrast gastrin-releasing peptide receptor-targeted nanobubbles.PDF
Translatable imaging agents are a crucial element of successful molecular imaging. Photoacoustic molecular imaging relies on optical absorbing materials to generate a sufficient signal. However, few materials approved for human use can generate adequate photoacoustic responses. Here we report a new nanoengineering approach to further improve photoacoustic response from biocompatible materials. Our study shows that when optical absorbers are incorporated into the shell of a gaseous nanobubble, their photoacoustic signal can be significantly enhanced compared to the original form. As an example, we constructed nanobubbles using biocompatible indocyanine green (ICG) and biodegradable poly(lactic-co-glycolic acid) (PLGA). We demonstrated that these ICG nanobubbles generate a strong ultrasound signal and almost four-fold photoacoustic signal compared to the same concentration of ICG solution; our theoretical calculations corroborate this effect and elucidate the origin of the photoacoustic enhancement. To demonstrate their molecular imaging performance, we conjugated gastrin-releasing peptide receptor (GRPR) targeting ligands with the ICG nanobubbles. Our dual photoacoustic/ultrasound molecular imaging shows a more than three-fold enhancement in targeting specificity of the GRPR-targeted ICG nanobubbles, compared to untargeted nanobubbles or prostate cancer cells not expressing GRPR, in a prostate cancer xenograft mouse model in vivo.</p
Biomimetic-Membrane-Protected Plasmonic Nanostructures as Dual-Modality Contrast Agents for Correlated Surface-Enhanced Raman Scattering and Photoacoustic Detection of Hidden Tumor Lesions
Optical imaging and spectroscopic
modalities are of considerable current interest for in vivo cancer
detection and image-guided surgery, but the turbid or scattering nature
of biomedical tissues has severely limited their abilities to detect
buried or occluded tumor lesions. Here we report the development of
a dual-modality plasmonic nanostructure based on colloidal gold nanostars
(AuNSs) for simultaneous surface-enhanced Raman scattering (SERS)
and photoacoustic (PA) detection of tumor phantoms embedded (hidden)
in ex vivo animal tissues. By using red blood cell membranes as a
naturally derived biomimetic coating, we show that this class of dual-modality
contrast agents can provide both Raman spectroscopic and PA signals
for the detection and differentiation of hidden solid tumors with
greatly improved depths of tissue penetration. Compared to previous
polymer-coated AuNSs, the biomimetic coatings are also able to minimize
protein adsorption and cellular uptake when exposed to human plasma
without compromising their SERS or PA signals. We further show that
tumor-targeting peptides (such as cyclic RGD) can be noncovalently
inserted for targeting the ανβ3-integrin
receptors expressed on metastatic cancer cells and tracked via both
SERS and PA imaging (PAI). Finally, we demonstrate image-guided resections
of tumor-mimicking phantoms comprising metastatic tumor cells buried
under layers of skin and fat tissues (6 mm in thickness). Specifically,
PAI was used to determine the precise tumor location, while SERS spectroscopic
signals were used for tumor identification and differentiation. This
work opens the possibility of using these biomimetic dual-modality
nanoparticles with superior signal and biological stability for intraoperative
cancer detection and resection