Molecular Imaging and Biology
DOI 10.1007/s11307-021-01654-5

RESEARCH ARTICLE

Potential of Gold Nanoparticles
for Noninvasive Imaging and Therapy
for Vascular Inflammation
Gold Nanoparticles for Vascular Imaging and Therapy

Hisanori Kosuge1 , Maki Nakamura2, Ayako Oyane2, Kazuko Tajiri3, Nobuyuki Murakoshi3,
Satoshi Sakai3, Akira Sato3, Atsushi Taninaka4, Taishiro Chikamori1, Hidemi Shigekawa4, andKazutaka Aonuma3
1Department of Cardiology, Tokyo Medical University, 6‑7‑1 Nishishinjuku, Shinjuku‑ku, 160‑0023 Tokyo, Japan
2
Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1‑1‑1 Higashi,
Tsukuba, Ibaraki 305‑8565, Japan3
Department of Cardiology, Faculty of Medicine, University of Tsukuba, 1‑1‑1 Tennodai, Tsukuba, Ibaraki 305‑8575, Japan
4
Faculty of Pure and Applied Sciences, University of Tsukuba, 1‑1‑1 Tennodai, Ibaraki 305‑8573 Tsukuba, Japan 2021
Abstract
Purpose: Macrophages contribute to the progression of vascular inflammation, making them usefultargets for imaging and treatment of vascular diseases. Gold nanoparticles (GNPs) are useful as computed tomography (CT) contrast agents and light absorbers in photothermal therapy. In this study,
we aimed to assess the viability of macrophages incubated with GNPs after near-infrared (NIR) laser
light exposure and to evaluate the utility of intravenously injected GNPs for in vivo imaging of vascularinflammation in mice using micro-CT.
Procedures: Mouse macrophage cells (RAW 264.7) were incubated with GNPs and assessed for GNP cellular
uptake and cell viability before and after exposure to NIR laser light. For in vivo imaging, macrophage-richatherosclerotic lesions were induced by carotid ligation in hyperlipidemic and diabetic FVB mice (n = 9).
Abdominal aortic aneurysms (AAAs) were created by angiotensin II infusion in ApoE-deficient mice (n = 9).
These mice were scanned with a micro-CT imaging system before and after the intravenous injection of GNPs.
Results: The CT attenuation values of macrophages incubated with GNPs were significantly higher
than those of cells incubated without GNPs (p < 0.04). Macrophages incubated with and without GNPs
showed similar viability. The viability of macrophages incubated with GNPs (100 μg/ml or 200 μg/ml)
was decreased by high-intensity NIR laser exposure but not by low-intensity NIR laser exposure. In
vivo CT images showed higher CT attenuation values in diseased carotid arteries than in non-diseased
contralateral arteries, although the difference was not statistically significant. The CT attenuation valuesof the perivascular area in AAAs of mice injected with GNPs were significantly higher than those ofmice without injection (p = 0.0001).
Conclusions: Macrophages with GNPs had reduced viability upon NIR laser exposure. GNPs intravenously injected into mice accumulated in sites of vascular inflammation, allowing detection of carotid
atherosclerosis and AAAs in CT imaging. Thus, GNPs have potential as multifunctional biologicallycompatible particles for the detection and therapy of vascular inflammation.

Key words Gold nanoparticle · Inflammation · Computed tomography · Macrophage
Correspondence to: Hisanori Kosuge; e-mail: hkosuge@
tokyo-med.ac.jp

Vol.:(0123456789)

Molecular Imaging and Biology

Introduction

In Vitro Uptake

Atherosclerosis is widely accepted as a chronic, systemic
vascular inflammatory disorder and remains the main causeof mortality in industrialized and developing nations [1].
Abdominal aortic aneurysm (AAA) is a common and lethal
degenerative disease. AAA expansion is associated with
the infiltration of inflammatory cells and degradation of
the extracellular matrix in the arterial wall [2]. In vascularinflammation, macrophages play a key role in plaque formation, aneurysm progression, and rupture. Therefore, macrophages can be a useful target for the imaging and treatmentof vascular diseases [3–5].
Gold nanoparticles (GNPs) can be used as contrast agentsfor X-ray computed tomography (CT) imaging of tumors andblood pools [6, 7]. CT imaging has demonstrated enhanced
accumulation of GNPs conjugated with antibodies or peptides in targeted organs [8, 9]. Micro-CT imaging showed theuptake of GNPs into murine macrophages after co-incubation. In addition, GNPs were able to detect soft tissue inflammation in a murine hind leg edema model [10]. GNPs including gold nanorods, gold nanoshells, and gold nanocages canbe used as light absorbers for photothermal ablation whichconvert photon energy to heat and induce hyperthermia upon
exposure to laser light [11–13].
Thermal ablation therapies using laser, microwave, radiofrequency, and high-intensity focused ultrasound have beendeveloped for the clinical treatment of cancers [14–17]. An
important issue in these therapies is insufficient targetability;
thermal ablation can damage healthy cells surrounding cancer cells. To overcome this challenge, previous studies havereported that thermal ablation therapy using a near-infrared(NIR) laser or an alternating magnetic field was effective
for the treatment of cancer in mice injected with different
types of nanoparticles [18, 19]. We have reported the effectof photothermal ablation of vascular macrophages using
single-walled carbon nanotubes in a murine atherosclerotic
model [20].
In this study, we evaluated the hypothesis that NIR laser
exposure could reduce the viability of macrophages with
GNPs and intravenously injected GNPs could image vascularinflammation in mice with micro-CT.

GNPs (AuroVist™ 15 nm) were purchased from Nanoprobes,
Inc. (USA). Macrophages were incubated with GNPs (0, 50,
100, and 200 μg/ml) at 37 °C under 5% ­CO2 for 24 h. Afterwashing in phosphate-buffered saline (Thermo Fisher Scientific Inc.), the macrophages were collected and scanned witha micro-CT imaging system (LaTheta LCT-100A, Aloka Co.,
Japan). The CT attenuation values were calculated using animage-analysis software on a dedicated workstation (Ziostation2; Ziosoft, Inc., Japan).

Materials and Methods
Cell Culture
Mouse macrophage cells (RAW 264.7) were cultured in
Dulbecco’s modified Eagle’s medium (Sigma-Aldrich Co.
LLC., USA) supplemented with 10% fetal bovine serum(Thermo Fisher Scientific Inc., USA) and 1% streptomycin/
penicillin (Thermo Fisher Scientific Inc.) at 37 °C in a 5% ­CO2
atmosphere.

Cell Viability
Macrophages (1 × ­105/well) were seeded in 96-well plates
and incubated at 37 °C under 5% ­CO2 for 24 h. Then, GNPs
were added to the wells at different concentrations (0, 50,
100, and 200 μg/ml), and the macrophages were incubatedfor another 24 h. Next, 10 μl of a Cell Counting Kit-8 (CCK8) solution (Dojindo Laboratories, Japan) was added to eachwell and the plates were incubated at 37 °C under 5% ­CO2
for 2 h. For each concentration group, wells without adding the CCK-8 solution were prepared as the corresponding
negative control. The absorbance was measured at 450 nm
in triplicate using a microplate reader (Varioskan LUX Multimode Microplate Reader, Thermo Fisher Scientific Inc.).
The absorbance of corresponding negative controls was subtracted from the measured absorbance of each concentrationgroup to compensate for the effect of GNPs. The results wereexpressed as relative values to cells without GNPs, whichwere set as 100% [21].

In Vitro NIR Laser Exposure
Macrophages were incubated with GNPs (0, 100, and 200 μg/ml) at 37 °C under 5% ­CO2 for 24 h. Ten million cells withor without GNPs were exposed to NIR laser light (Mira-HP,
COHERENT, Inc. USA, wavelength: 830 nm, pulse width:
200 fs, irradiation diameter: 1 c­ m2) for 0, 10, and 20 min at
178, 196, 400, and 437 mW. Macrophages with and withoutlaser exposure were cultured at 37 °C under 5% C
­ O2 for 24 h
to evaluate their viability. The absorbance at 450 nm was measured in triplicate using CCK-8, as described above. The absorbance measured for the macrophages with laser exposure wasnormalized to that of the macrophages without laser exposure.

In Vivo CT
All animal procedures were approved by the Institutional
Animal Experiment Committee of the University of Tsukuba.
All animals were anesthetized with ketamine and xylazine
for surgical and imaging procedures and were allowed freeaccess to food and water.
For carotid ligation, 8-week-old male FVB mice (n = 9)
were fed a high-fat diet. After 4 weeks on the diet, diabetes

Molecular Imaging and Biology

mice were injected with GNPs (10 mg/mouse) via the tailvein and scanned with a micro-CT imaging system at 24 and48 h. Four mice without injection were also scanned at 24
and 48 h. After in vivo imaging, the aortas were surgically
exposed and ex vivo imaging was performed using a microCT imaging system.

Statistical Analyses

Fig. 1  In vitro CT attenuation values of macrophages incubatedwith and without GNPs. The CT attenuation values of macrophages incubated with GNPs were significantly higher thanthose of macrophages without GNPs. *p < 0.03 vs. macrophages
without GNPs, **p < 0.04 vs. macrophages without GNPs.

All data are expressed as the mean ± standard error of
the mean (SEM). The Kruskal–Wallis test was used tocompare in vitro CT attenuation values and cell viability
between macrophages with and without GNPs, followed bypost hoc testing using the Mann–Whitney U test with Bonferroni adjustment. Two-way repeated measure analysis ofvariance was used to compare serial in vivo CT attenuation
values between ligated left and non-ligated right common
carotid arteries and between AAAs injected with GNPs
and those without injection. The Wilcoxon signed-rank
test was used to compare the ratio of CT attenuation values
in the carotid arteries and AAAs between 24 and 48 h after
injection of GNPs. The Mann–Whitney U test was used
to compare cell viability between macrophages with andwithout GNPs after in vitro laser exposure and ex vivo CT
attenuation values between AAAs injected with GNPs andthose without injection. P < 0.05 was considered statistically significant.

Results
In Vitro Uptake and Viability
Fig. 2  Cell viability by CCK-8 assay. Macrophages incubated with
GNPs at a dose of 50, 100, or 200 μg/ml showed a similar viability
as those without GNPs.

was induced by five daily intraperitoneal injections of streptozotocin (STZ 40 mg/kg, Sigma-Aldrich Co. LLC.). Two
weeks after the STZ injection, the left common carotid artery
was ligated below the bifurcation to develop macrophagerich neointimal proliferation. The non-ligated right common
carotid artery served as the control [4]. Two weeks after
the ligation, mice were injected with GNPs (5 FVB mice:
10 mg/mouse, 4 FVB mice: 20 mg/mouse) via the tail veinand scanned with a micro-CT imaging system at 24 and 48 h.
AAAs were induced in male apolipoprotein E-deficient
mice, 14—24 weeks of age, by continuous angiotensin II
infusion via subcutaneously implanted osmotic mini-pumps[22]. Two weeks later, transabdominal 40-MHz B-mode
ultrasound imaging (Vevo 2100, VisualSonics Inc., Toronto,
Canada) was performed to assess the aortic diameter. Micewith suprarenal aortic dissection (n = 9) were studied. FiveThe CT attenuation values of macrophages incubated with
GNPs at doses of 50, 100, and 200 μg/ml were significantly
higher than those of cells without GNPs (Fig. 1). The viability of macrophages incubated with GNPs (50, 100, and200 μg/ml) did not decrease compared to that of macrophages
without GNPs (Fig. 2).

In Vitro Laser Exposure
High-intensity NIR laser light exposure significantly reduced
the viability of macrophages treated with GNPs (100 μg/
ml or 200 μg/ml) compared to macrophages without GNPs
(100 μg/ml: 0.650 ± 0.018 vs. 0.962 ± 0.005, p < 0.05, Fig. 3a;
200 μg/ml: 0.539 ± 0.041 vs. 0.999 ± 0.030, p < 0.05, Fig. 3c).
However, the viability of macrophages incubated with GNPs
(100 μg/ml or 200 μg/ml) was not reduced by low-intensity
NIR laser light exposure (100 μg/ml: 1.061 ± 0.034 vs.
1.088 ± 0.018, p = 0.8273, Fig. 3b; 200 μg/ml: 1.000 ± 0.018
vs. 0.981 ± 0.052, p = 0.8273, Fig. 3d).

Molecular Imaging and Biology

Fig. 3  In vitro NIR laser exposure. a, b NIR laser exposurein macrophages incubated withand without GNPs (100 μg/ml). a Viability of macrophages
irradiated with high-intensity
NIR laser (400 mW) was
significantly decreased by preincubation with GNPs. *p < 0.05.
b Viability of macrophages
irradiated with low-intensity
NIR laser (178 mW) was notdecreased by preincubation with
GNPs. c, d NIR laser exposurein macrophages with and without GNPs (200 μg/ml). c Viability of macrophages irradiatedwith high-intensity NIR laser(437 mW) was significantly
decreased by preincubation with
GNPs. *p < 0.05. d Viabilityof macrophages irradiated with
low-intensity NIR laser (196mW) was not decreased bypreincubation with GNPs.

In Vivo CT Imaging
In carotid ligation models, in vivo CT images exhibited contrast enhancement in the ligated left and non-ligated rightcarotid arteries at 24 h and 48 h after injection of GNPs inboth the 10 mg and 20 mg groups (Fig. 4a). The serial CT
attenuation values showed no significant differences between
ligated left carotid arteries and non-ligated right carotid arteries in both groups (10 mg, p = 0.4417; 20 mg, p = 0.2519;

Fig. 4b). The ratio of the CT attenuation values of ligated left
carotid arteries to those of non-ligated right carotid arteries
was compared between 24 and 48 h (Fig. 4c). The ratio washigher at 48 h than 24 h in both the 10 mg and 20 mg groups,
although statistical significance was not observed in eithergroup (10 mg: 0.841 ± 0.165 vs. 1.510 ± 0.470, p = 0.285;
20 mg: 1.238 ± 0.147 vs. 1.853 ± 0.526, p = 0.1088).

Molecular Imaging and Biology

Fig. 4  In vivo CT imaging ofmurine carotid arteries after
injection of GNPs. a Representative serial in vivo CT images
before and after injection of
GNPs at a dose of 10 mg/mouse(top) or 20 mg/mouse (bottom).
CT images exhibited contrast
enhancement in ligated left
(yellow arrows) and non-ligatedright (red arrows) carotid
arteries at 24 and 48 h after
injection of GNPs. b The CT
attenuation values showed nosignificant differences between
ligated left carotid arteries andnon-ligated right carotid arteries in both 10 mg and 20 mggroups. 10 mg, p = 0.4417;
20 mg, p = 0.2519. c The ratioof the CT attenuation values ofligated left carotid arteries tonon-ligated right carotid arteries
at 48 h was higher than that at
24 h in both 10 mg and 20 mggroups, although statistical differences were not seen. 10 mg,
p = 0.285; 20 mg, p = 0.1088.

In AAA models, CT images exhibited contrast enhancement in the perivascular area in AAAs after injection of
GNPs, whereas no enhancement was observed without
injection of GNPs (Fig. 5a). The serial CT attenuation
values of the perivascular area after injection of GNPs
were significantly higher than those without injection(p = 0.0001, Fig. 5b). The ratio of the CT attenuation values of perivascular areas to those of aortic lumens at 48 h
after injection was significantly higher than that at 24 h inAAAs (2.448 ± 0.263 vs. 1.595 ± 0.071, p < 0.05; Fig. 5c).
Ex vivo imaging showed that the CT attenuation valuesof the perivascular area in mice injected with GNPs weresignificantly higher than those in mice without injection(308.4 ± 24.9 vs. 126.3 ± 42.2, p < 0.03; Fig. 5d).

Discussion
In this study, we demonstrated that CT imaging with GNPs
can detect vascular inflammation in murine carotid ligation
and AAA models. In addition, in vitro laser exposure reduced
the viability of the macrophages incubated with GNPs.
Imaging techniques for vascular inflammation may be
useful for the characterization of biological activity in atherosclerosis and aneurysm. Molecular imaging of vascularMolecular Imaging and Biology

Fig. 5  In vivo CT imaging ofmurine AAAs after injection of
GNPs. a Representative serial
in vivo CT images of AAAs
injected with (top) and without(bottom) GNPs. The CT images
exhibited contrast enhancementin the perivascular area (yellow
arrows) in AAAs after injectionof GNPs (10 mg/mouse) andlimited enhancement without
injection of GNPs. b The CT
attenuation values of perivascular area with GNPs were significantly higher than those without
GNPs over time. *p = 0.0001. c
The ratio of the CT attenuation
values of perivascular areas toaortic lumens was significantly
higher at 48 h than at 24 h inAAAs with GNPs. *p < 0.05.
d The CT imaging of representative ex vivo aorta with andwithout injection of GNPs (top).
Yellow arrows show the accumulation of GNPs in perivascular area. The CT attenuation
values of perivascular area inmice with injection of GNPs
were significantly higher thanthose in mice without injectionof GNPs (bottom). *p < 0.03.

inflammation is a promising approach to improve the detection, understanding, and characterization of the progressof atherosclerosis and aneurysm noninvasively [3, 4, 23,24]. Atherosclerotic lesions and AAAs often contain abundant macrophages, which play crucial roles not only in thedevelopment of atherosclerosis and AAAs, but also in the
disruption of vulnerable atherosclerotic plaques and AAAs.

Therefore, macrophages have emerged as key imaging andtherapeutic targets for atherosclerosis and AAAs.
X-ray CT imaging is particularly useful as a diagnostic toolfor various diseases in terms of resolution, efficiency, and cost
[13, 15]. Iodine contrast agents are widely used for CT imaging because of their high X-ray absorption coefficients. However, they have several limitations including short circulation,

Molecular Imaging and Biology

allergic reactions, and renal toxicity [13]. Nanoparticle-based
contrast agents with long circulation and good biocompatibility may enable safe and reliable noninvasive imaging [25, 26].
Previous studies have shown that GNPs are promising materials for CT contrast agents because of their prolonged blood
circulation, good biocompatibility, and higher attenuation
coefficient compared to the iodine contrast agents [13–16].
GNPs can be used for visualization of the vascular network and kidneys, as well as tumors and areas of inflammation [20, 27]. Factors such as size, shape, surface charge, andsurface functionalization affect the cellular uptake of nanoparticles. Chhour et al. [28] reported that 50 nm and 75 nm GNPs
functionalized poly(ethylene-glycol) carboxylic acid ligands(PCOOH) showed higher cellular uptake than 15 nm and 25 nm
GNPs functionalized PCOOH. On the other hand, GNPs functionalized carboxylic acid between 15 and 50 nm exhibited highcellular uptake. Because 15-nm GNPs showed a higher contrast
than 1.9 nm GNPs in both in vitro and in vivo [10], 15-nm
GNPs were used in this study. The surface functionalization of
nanoparticles plays a key role in toxicity reduction. Most GNPs
show no toxicity in vitro [28, 29]. In addition, GNPs mainly
accumulate in the liver and spleen without inducing organ toxicity after intravenous administration in mice [30, 31]. In thisstudy, we showed that the viability of macrophages incubatedwith GNPs at Au concentrations from 50 to 200 μg/ml was thesame as that of macrophages incubated without GNPs (Fig. 2),
suggesting that GNPs are nontoxic in the given concentration
range and available for in vivo imaging. Then, we have demonstrated in vivo CT imaging of vascular inflammation with GNPs
in murine carotid ligation and AAA models. The CT images
exhibited contrast enhancement of atherosclerotic lesions andaortic aneurysms after injection of GNPs (Figs. 4a and 5a),suggesting the accumulation of GNPs at inflammatory sites.
The ratio of the CT attenuation values of inflammatory sites
to normal sites was higher at 48 h than at 24 h after injection
in AAA models due to prolonged blood circulation of GNPs
(Fig. 5c). Although in vivo imaging at a short time point (24 h)could detect the inflammatory sites, serial imaging over a longer
period may be useful to further improve contrast enhancement.
The ratio of the CT attenuation values of ligated left carotid
arteries to those of non-ligated right carotid arteries between 24
and 48 h in carotid ligation models showed no significant difference (Fig. 4c), which may be due to the small area of inflammatory sites in ligated carotid arteries compared to abdominal
aortas. The number of GNPs estimated by the CT attenuation
values is close to one in a previous study [10]. However, quantitative data are useful to evaluate the accumulation of GNPs
in vitro and in vivo.
Another potential application of GNPs is photothermal
therapy. GNPs, including gold nanorods, gold nanoshells, andgold nanocages, exhibit optical absorption in the NIR region[18–20]. These nanoparticles showed therapeutic efficacy forsolid tumors in animal models using continuous-wave NIR
laser light irradiation. A pulsed laser can reach a higher temperature and penetrate more deeply into the tissue than a continuous-wave laser [32, 33]. Therefore, we used a pulsed laser

to perform an in vitro laser irradiation study and demonstrated
a significant reduction in viability in macrophages incubatedwith GNPs by pulsed NIR light irradiation (Fig. 3). A different setting of laser intensity was used in each concentrationgroup. An optical parametric oscillator equipped in the laser
system was able to change the output wavelength. However, it
was difficult to stabilize the laser intensity due to the angle ofnonlinear optical crystals and temperature. Thus, comparing
cell viability results between 100 and 200 μg/ml may be challenging. Ghaghada et al. [34] recently reported the detection ofaortic degeneration in a murine aortic aneurysm model using
gold nanoparticles. They performed CT angiography (CTA)
and delayed CT imaging (CTD) for various stages of aortic
aneurysm and dissection and showed that CTD enabled thedetection of aortic injury in not only moderate-advanced stages
but also early stages. Although the detection of AAAs was seen
only in the advanced stage in this study, we showed the detection of carotid atherosclerosis and the potential for therapy
for vascular inflammation using NIR laser. However, reduced
cellular viability was achieved only by high-intensity laser
irradiation and long irradiation time, and the mechanism of
reduced viability was unclear. Because the blood flow throughblood vessels leads to insufficient heating of the target [35], it
may be difficult to induce the reduction of in vivo cell viability
under the same laser conditions as in vitro. Further studies are
required to examine the effects and setting of laser irradiation.

Conclusions
In conclusion, in vivo CT imaging with GNPs successfully
depicted experimental carotid atherosclerosis and AAAs, andNIR laser irradiation reduced the viability of macrophages
incubated with GNPs. Thus, GNPs have a strong potential for noninvasive CT imaging and therapy for vascularinflammation.
Author Contribution H.K. designed the study, collected and analyzed data,
and wrote the manuscript. M.N. and A.O. designed the study and reviewed
and edited the manuscript. K.T., N.M., S.S., A.S., and A.T. acquired the data.
T.C., H.S., and K.A. reviewed and edited the manuscript.
Funding This study was supported by JSPS KAKENHI Grant Numbers
JP16H03831, JP16K09511, and JP19K08496.
Declarations
Conflict of Interest The authors declare that they have no conflict of interest.
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References
1. Libby P (2002) Inflammation in atherosclerosis. Nature 420:868–874
2. Shimizu K, Mitchell RN, Libby P (2006) Inflammation and cellular immune responses in abdominal aortic aneurysms. Arterioscler
Thromb Vasc Biol 26:987–994
3. Kitagawa T, Kosuge H, Uchida M et al (2017) RGD targeting of humanferritin iron oxide nanoparticles enhances in vivo MRI of vascularinflammation and angiogenesis in experimental carotid disease andabdominal aortic aneurysm. J Magn Reson Imaging 45:1144–1153
4. Kosuge H, Sherlock SP, Kitagawa T et al (2011) FeCo/graphite
nanocrystals for multi-modality imaging of experimental vascularinflammation. PLoS One 6:e14523
5. Morishige K, Kacher DF, Libby P et al (2010) High-resolution magnetic resonance imaging enhanced with superparamagnetic nanoparticles measures macrophage burden in atherosclerosis. Circulation
122:1707–1715
6. Kim D, Park S, Lee JH, Jeong YY, Jon S (2007) Antibiofouling polymer-coated gold nanoparticles as a contrast agent for in vivo X-ray
computed tomography imaging. J Am Chem Soc 20:7661–7665
7. Ye K, Qin J, Peng Z et al (2014) Polyethylene glycol-modified dendrimer-entrapped gold nanoparticles enhance CT imaging of blood poolin atherosclerotic mice. Nanoscale Res Lett 26:529
8. Reuveni T, Motiei M, Romman Z, Popovtzer A, Popovtzer R (2011)
Targeted gold nanoparticles enable molecular CT imaging of cancer:
an in vivo study. Int J Nanomedicine 6:2859–2864
9. Danila D, Johnson E, Kee P (2013) CT imaging of myocardial scars
with collagen-targeting gold nanoparticles. Nanomedicine 9:1067–1076
10. Domey J, Teichgräber U, Hilger I (2015) Gold nanoparticles allow
detection of early-stage edema in mice via computed tomography imaging. Int J Nanomedicine 10:3803–3814
11. Dickerson EB, Dreaden EC, Huang X et al (2008) Gold nanorod
assisted near-infrared plasmonic photothermal therapy (PPTT) of
squamous cell carcinoma in mice. Cancer Lett 269:57–66
12. O’Neal DP, Hirsch LR, Halas NJ, Payne JD, West JL (2004) Photothermal tumor ablation in mice using near infrared-absorbing nanoparticles. Cancer Lett 209:171–176
13. Chen J, Glaus C, Laforest R et al (2010) Gold nanocages as photothermal transducers for cancer treatment. Small 6:811–817
14. Nikfarjam M, Muralidharan V, Malcontenti-Wilson C, Christophi C(2005) Progressive microvascular injury in liver and colorectal liver
metastases following laser induced focal hyperthermia therapy. Lasers
Surg Med 37:64–73
15. Ohmoto K, Yoshioka N, Tomiyama Y et al (2009) Comparison oftherapeutic effects between radiofrequency ablation and percutaneous
microwave coagulation therapy for small hepatocellular carcinomas. J
Gastroenterol Hepatol 24:223–227
16. Dooley WC, Vargas HI, Fenn AJ, Tomaselli MB, Harness JK (2010)
Focused microwave thermotherapy for preoperative treatment ofinvasive breast cancer: a review of clinical studies. Ann Surg Oncol
17:1076–1093
17. Rouvière O, Curiel L, Chapelon JY et al (2004) Can color doppler
predict the uniformity of HIFU-induced prostate tissue destruction?
Prostate 60:289–297
18. Johannsen M, Thiesen B, Jordan A et al (2005) Magnetic fluid hyperthermia (MFH) reduces prostate cancer growth in the orthotopic Dunning R3327 rat model. Prostate 64:283–292

19. Robinson JT, Welsher K, Tabakman SM et al (2010) High performancein vivo near-IR (>1 μm) imaging and photothermal cancer therapy withcarbon nanotubes. Nano Res 3:779–793
20. Kosuge H, Sherlock SP, Kitagawa T et al (2012) Near infrared imaging
and photothermal ablation of vascular inflammation using single-walledcarbon nanotubes. J Am Heart Assoc 1:e002568
21. Nakamura M, Oyane A, Kuroiwa K et al (2018) Facile one-pot fabrication of calcium phosphate-based composite nanoparticles as delivery
and MRI contrast agents for macrophages. Colloids Surf B Biointerfaces 162:135–145
22. Kitagawa T, Kosuge H, Chang E et al (2013) Integrin-targeted molecular imaging of experimental abdominal aortic aneurysms by (18)
F-labeled Arg-Gly-Asp positron-emission tomography. Circ Cardiovasc
Imaging 6:950–956
23. Kietselaer BL, Reutelingsperger CP, Heidendal GA et al (2004)
Noninvasive detection of plaque instability with use of radiolabeledannexin A5 in patients with carotid-artery atherosclerosis. N Engl J
Med 350:1472–1473
24. Jaffer FA, Kim DE, Quinti L et al (2007) Optical visualization of cathepsin K activity in atherosclerosis with a novel, protease-activatable
fluorescence sensor. Circulation 115:2292–2298
25. Rabin O, Manuel Perez J, Grimm J, Wojtkiewicz G, Weissleder R(2006) An X-ray computed tomography imaging agent based on longcirculating bismuth sulphide nanoparticles. Nat Mater 5:118–122
26. Lee JH, Sherlock SP, Terashima M et al (2009) High-contrast in vivo
visualization of microvessels using novel FeCo/GC magnetic nanocrystals. Magn Reson Med 62:1497–1509
27. Lusic H, Grinstaff MW (2013) X-ray-computed tomography contrast
agents. Chem Rev 113:1641–1666
28. Chhour P, Kim J, Benardo B et al (2017) Effect of gold nanoparticle
size and coating on labeling monocytes for CT tracking. Bioconjug
Chem 28:260–269
29. Correard F, Maximova K, Estève MA et al (2014) Gold nanoparticles
prepared by laser ablation in aqueous biocompatible solutions: assessment of safety and biological identity for nanomedicine applications.
Int J Nanomedicine 9:5415–5430
30. Yang L, Kuang H, Zhang W et al (2017) Comparisons of the biodistribution and toxicological examinations after repeated intravenous
administration of silver and gold nanoparticles in mice. Sci Rep 7:3303
31. Bailly AL, Correard F, Popov A et al (2019) In vivo evaluation ofsafety, biodistribution and pharmacokinetics of laser-synthesized gold
nanoparticles. Sci Rep 9:12890
32. Avedisian CT, Cavicchi RE, McEuen PL, Zhou X (2009) Nanoparticles for cancer treatment: role of heat transfer. Ann N Y Acad Sci
1161:62–73
33. Ando T, Xuan W, Xu T et al (2011) Comparison of therapeutic effects
between pulsed and continuous wave 810-nm wavelength laser irradiation for traumatic brain injury in mice. PLoS One 6:e26212
34. Ghaghada KB, Ren P, Devkota L et al (2021) Early detection of aortic
degeneration in a mouse model of sporadic aortic aneurysm and dissection using nanoparticle contrast-enhanced computed tomography.
Arterioscler Thromb Vasc Biol 41:1534–1548
35. Paul A, Narasimhan A, Kahlen FJ, Das SK (2014) Temperature evolution in tissues embedded with large blood vessels during photo-thermal
heating. J Therm Biol 41:77–87

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