Professional Education

  • Doctor of Philosophy, Department of Electrical and Computer Engineering, the University of Texas at Austin, Electrical and Computer Engineering (2012)
  • Master of Science, CREOL & FPCE-College of Optics & Photonics, University of Central Florida, Optics (2008)

Stanford Advisors


  • S. Emelianov, J. Su, B. Wang, A. Karpiouk, Yun-Sheng Chen, W. Frey, R. Bouchard. "United States Patent 20,120,253,180 Combined ultrasound and photoacoustic imaging of metal objects"
  • S. Emelianov, B. Wang, J. Shah, K. Sokolov, J. Su, Yun-Sheng Chen, W. Frey. "United States Patent 20120125107 A Temperature dependent photoacoustic imaging"

All Publications

  • Photoacoustic and ultrasound imaging using dual contrast perfluorocarbon nanodroplets triggered by laser pulses at 1064 nm BIOMEDICAL OPTICS EXPRESS Hannah, A. S., VanderLaan, D., Chen, Y., Emelianov, S. Y. 2014; 5 (9): 3042–52

    View details for DOI 10.1364/BOE.5.003042

    View details for Web of Science ID 000341650900015

    View details for PubMedID 25401018

  • Intravascular Photoacoustics for Image-Guidance and Temperature Monitoring During Plasmonic Photothermal Therapy of Atherosclerotic Plaques: A Feasibility Study THERANOSTICS Yeager, D., Chen, Y., Litovsky, S., Emelianov, S. 2014; 4 (1): 36–46

    View details for DOI 10.7150/thno.7143

    View details for Web of Science ID 000331402100004

    View details for PubMedID 24396514

  • Silica-coated gold nanoplates as stable photoacoustic contrast agents for sentinel lymph node imaging NANOTECHNOLOGY Luke, G. P., Bashyam, A., Homan, K. A., Makhija, S., Chen, Y., Emelianov, S. Y. 2013; 24 (45): 455101


    A biopsy of the first lymph node to which a tumor drains-the sentinel lymph node (SLN)-is commonly performed to identify micrometastases. Image guidance of the SLN biopsy procedure has the potential to improve its accuracy and decrease its morbidity. We have developed a new stable contrast agent for photoacoustic image-guided SLN biopsy: silica-coated gold nanoplates (Si-AuNPs). The Si-AuNPs exhibit high photothermal stability when exposed to pulsed and continuous wave laser irradiation. This makes them well suited for in vivo photoacoustic imaging. Furthermore, Si-AuNPs are shown to have low cytotoxicity. We tested the Si-AuNPs for SLN mapping in a mouse model where they exhibited a strong, sustained photoacoustic signal. Real-time ultrasound and photoacoustic imaging revealed that the Si-AuNPs quickly drain to the SLN, gradually spreading throughout a large portion of the node.

    View details for DOI 10.1088/0957-4484/24/45/455101

    View details for Web of Science ID 000326081400004

    View details for PubMedID 24121616

    View details for PubMedCentralID PMC4000721

  • Sensitivity enhanced nanothermal sensors for photoacoustic temperature mapping JOURNAL OF BIOPHOTONICS Chen, Y., Frey, W., Walker, C., Aglyamov, S., Emelianov, S. 2013; 6 (6-7): 534–42


    Photoacoustic imaging can be used to guide and validate the therapeutic outcome of nanoparticle-mediated photothermal therapy through its ability to visualize the delivery of nanoparticle contrast agents, image the temperature distribution inside living tissue, and confirm tissue coagulation. In this image-guided process, temperature mapping plays a critical role for thermal dosage control. Therefore, developing a sensitive and accurate photoacoustic technique to quantitatively measure the temperature distribution during thermal therapy is essential. In this study, we investigated and demonstrated that silica-coated gold nanorods, can provide a multi-fold improvement in sensitivity of the photoacoustic temperature mapping compared to gold nanorods without silica coating, and serve as a nanothermal sensor to accurately and quantitatively visualize temperature distributions during photothermal therapy.

    View details for DOI 10.1002/jbio.201200219

    View details for Web of Science ID 000319743100011

    View details for PubMedID 23450812

  • Photoacoustic signal amplification through plasmonic nanoparticle aggregation JOURNAL OF BIOMEDICAL OPTICS Bayer, C. L., Nam, S., Chen, Y., Emelianov, S. Y. 2013; 18 (1): 16001


    Photoacoustic imaging, using targeted plasmonic metallic nanoparticles, is a promising noninvasive molecular imaging method. Analysis of the photoacoustic signal generated by plasmonic metallic nanoparticles is complex because of the dependence upon physical properties of both the nanoparticle and the surrounding environment. We studied the effect of the aggregation of gold nanoparticles on the photoacoustic signal amplitude. We found that the photoacoustic signal from aggregated silica-coated gold nanoparticles is greatly enhanced in comparison to disperse silica-coated gold nanoparticles. Because cellular uptake and endocytosis of nanoparticles results in their aggregation, these results have important implications for the application of plasmonic metallic nanoparticles towards quantitative molecular imaging.

    View details for DOI 10.1117/1.JBO.18.1.016001

    View details for Web of Science ID 000315157000008

    View details for PubMedID 23288414

    View details for PubMedCentralID PMC3536717

  • Environment-Dependent Generation of Photoacoustic Waves from Plasmonic Nanoparticles SMALL Chen, Y., Frey, W., Aglyamov, S., Emelianov, S. 2012; 8 (1): 47-52


    Nanoparticle-augmented photoacoustics is an emerging technique for molecular imaging. This study investigates the fundamental process of the photoacoustic signal generation by plasmonic nanoparticles suspended in a weakly absorbing fluid. The photoacoustic signal of gold nanospheres with varying silica shell thicknesses is shown to be dominated by the heat transfer between the nanoparticles and the surrounding environment.

    View details for DOI 10.1002/smll.201101140

    View details for Web of Science ID 000298788800006

    View details for PubMedID 22114029

  • In vivo three-dimensional spectroscopic photoacoustic imaging for monitoring nanoparticle delivery BIOMEDICAL OPTICS EXPRESS Kim, S., Chen, Y., Luke, G. P., Emelianov, S. Y. 2011; 2 (9): 2540–50


    In vivo monitoring of nanoparticle delivery is essential to better understand cellular and molecular interactions of nanoparticles with tissue and to better plan nanoparticle-mediated therapies. We developed a three-dimensional ultrasound and photoacoustic (PA) imaging system and a spectroscopic PA imaging algorithm to identify and quantify the presence of nanoparticles and other tissue constituents. Using the developed system and approach, three-dimensional in vivo imaging of a mouse with tumor was performed before and after intravenous injection of gold nanorods. The developed spectroscopic PA imaging algorithm estimated distribution of nanoparticle as well as oxygen saturation of blood. Moreover, silver staining of excised tumor tissue confirmed nanoparticle deposition, and showed good correlation with spectroscopic PA images. The results of our study suggest that three-dimensional ultrasound-guided spectroscopic PA imaging can monitor nanoparticle delivery in vivo.

    View details for DOI 10.1364/BOE.2.002540

    View details for Web of Science ID 000299883200009

    View details for PubMedID 21991546

    View details for PubMedCentralID PMC3184863

  • Multiplex photoacoustic molecular imaging using targeted silica-coated gold nanorods BIOMEDICAL OPTICS EXPRESS Bayer, C. L., Chen, Y., Kim, S., Mallidi, S., Sokolov, K., Emelianov, S. 2011; 2 (7): 1828–35


    The establishment of multiplex photoacoustic molecular imaging to characterize heterogeneous tissues requires the use of a tunable, thermally stable contrast agent targeted to specific cell types. We have developed a multiplex photoacoustic imaging technique which uses targeted silica-coated gold nanorods to distinguish cell inclusions in vitro. This paper describes the use of tunable targeted silica-coated gold nanorods (SiO(2)-AuNRs) as contrast agents for photoacoustic molecular imaging. SiO(2)-AuNRs with peak absorption wavelengths of 780 nm and 830 nm were targeted to cells expressing different cell receptors. Cells were incubated with the targeted SiO(2)-AuNRs, incorporated in a tissue phantom, and imaged using multiwavelength photoacoustic imaging. We used photoacoustic imaging and statistical correlation analysis to distinguish between the unique cell inclusions within the tissue phantom.

    View details for DOI 10.1364/BOE.2.001828

    View details for Web of Science ID 000299879500005

    View details for PubMedID 21750761

    View details for PubMedCentralID PMC3130570

  • Silica-Coated Gold Nanorods as Photoacoustic Signal Nanoamplifiers NANO LETTERS Chen, Y., Frey, W., Kim, S., Kruizinga, P., Homan, K., Emelianov, S. 2011; 11 (2): 348–54


    Photoacoustic signal generation by metal nanoparticles relies on the efficient conversion of light to heat, its transfer to the environment, and the production of pressure transients. In this study we demonstrate that a dielectric shell has a strong influence on the amplitude of the generated photoacoustic signal and that silica-coated gold nanorods of the same optical density are capable of producing about 3-fold higher photoacoustic signals than nanorods without silica coating. Spectrophotometry measurements and finite difference time domain (FDTD) analysis of gold nanorods before and after silica coating showed only an insignificant change of the extinction and absorption cross sections, hence indicating that the enhancement is not attributable to changes in absorption cross section resulting from the silica coating. Several factors including the silica thickness, the gold/silica interface, and the surrounding solvent were varied to investigate their effect on the photoacoustic signal produced from silica-coated gold nanorods. The results suggest that the enhancement is caused by the reduction of the gold interfacial thermal resistance with the solvent due to the silica coating. The strong contrast enhancement in photoacoustic imaging, demonstrated using phantoms with silica-coated nanorods, shows that these hybrid particles acting as "photoacoustic nanoamplifiers" are high efficiency contrast agents for photoacoustic imaging or photoacoustic image-guided therapy.

    View details for DOI 10.1021/nl1042006

    View details for Web of Science ID 000287049100008

    View details for PubMedID 21244082

    View details for PubMedCentralID PMC3040682

  • Magneto-photo-acoustic imaging BIOMEDICAL OPTICS EXPRESS Qu, M., Mallidi, S., Mehrmohammadi, M., Truby, R., Homan, K., Joshi, P., Chen, Y., Sokolov, K., Emelianov, S. 2011; 2 (2): 385–95


    Magneto-photo-acoustic imaging, a technique based on the synergy of magneto-motive ultrasound, photoacoustic and ultrasound imaging, is introduced. Hybrid nanoconstructs, liposomes encapsulating gold nanorods and iron oxide nanoparticles, were used as a dual-contrast agent for magneto-photo-acoustic imaging. Tissue-mimicking phantom and macrophage cells embedded in ex vivo porcine tissue were used to demonstrate that magneto-photo-acoustic imaging is capable of visualizing the location of cells or tissues labeled with dual-contrast nanoparticles with sufficient contrast, excellent contrast resolution and high spatial resolution in the context of the anatomical structure of the surrounding tissues. Therefore, magneto-photo-acoustic imaging is capable of identifying the nanoparticle-labeled pathological regions from the normal tissue, providing a promising platform to noninvasively diagnose and characterize pathologies.

    View details for DOI 10.1364/BOE.2.000385

    View details for Web of Science ID 000299873500017

    View details for PubMedID 21339883

    View details for PubMedCentralID PMC3038453

  • Prospects of molecular photoacoustic imaging at 1064 nm wavelength OPTICS LETTERS Homan, K., Kim, S., Chen, Y., Wang, B., Mallidi, S., Emelianov, S. 2010; 35 (15): 2663–65


    An analysis of the photoacoustic (PA) signal from murine tissue in vivo revealed several benefits of contrast-enhanced PA imaging at a wavelength of 1064nm. Of all the wavelengths tested in a range from 710 to 1064nm, the background PA signal from tissue in vivo was lowest and more homogeneous at 1064nm. For blood-laden tissue, the background PA signal was up to 70% less at 1064nm. Furthermore, when plasmonic nanoparticles, such as silver nanoplates, were introduced in vivo as contrast agents, the contrast in PA images at 1064nm increased 38% compared to 750nm. Therefore, contrast-enhanced PA imaging at 1064nm is advantageous because of the low and homogeneous signal from native tissue, enabling high contrast in PA imaging when exogenous, molecularly targeted agents are employed.

    View details for DOI 10.1364/OL.35.002663

    View details for Web of Science ID 000281056700055

    View details for PubMedID 20680092

    View details for PubMedCentralID PMC3059192

  • Enhanced thermal stability of silica-coated gold nanorods for photoacoustic imaging and image-guided therapy OPTICS EXPRESS Chen, Y., Frey, W., Kim, S., Homan, K., Kruizinga, P., Sokolov, K., Emelianov, S. 2010; 18 (9): 8867–77


    Photothermal stability and, therefore, consistency of both optical absorption and photoacoustic response of the plasmonic nanoabsorbers is critical for successful photoacoustic image-guided photothermal therapy. In this study, silica-coated gold nanorods were developed as a multifunctional molecular imaging and therapeutic agent suitable for image-guided photothermal therapy. The optical properties and photothermal stability of silica-coated gold nanorods under intense irradiation with nanosecond laser pulses were investigated by UV-Vis spectroscopy and transmission electron microscopy. Silica-coated gold nanorods showed increased photothermal stability and retained their superior optical properties under much higher fluences. The changes in photoacoustic response of PEGylated and silica-coated nanorods under laser pulses of various fluences were compared. The silica-coated gold nanorods provide a stable photoacoustic signal, which implies better imaging capabilities and make silica-coated gold nanorods a promising imaging and therapeutic nano-agent for photoacoustic imaging and image-guided photothermal therapy.

    View details for DOI 10.1364/OE.18.008867

    View details for Web of Science ID 000277082200016

    View details for PubMedID 20588732

    View details for PubMedCentralID PMC3404861

  • Capacitor-embedded 0.54 pJ/bit silicon-slot photonic crystal waveguide modulator OPTICS LETTERS Chen, X., Chen, Y., Zhao, Y., Jiang, W., Chen, R. T. 2009; 34 (5): 602–4


    A high-speed compact silicon modulator based on the lateral capacitor configuration is experimentally demonstrated with low-power consumption and 3 dB modulation depth. The capacitor layout is introduced to scale down the total modulator capacitance to 30x10(-15) F, which effectively reduces the rf power consumption to 0.54 pJ/bit. Exploiting the slow group velocity of light in the slot photonic crystal waveguides, the device reported herein exhibits higher modulation efficiency than conventional capacitor modulator and provides a V(pi)L figure of merit of 0.18 Vcm at the wavelength of 1548 nm.

    View details for DOI 10.1364/OL.34.000602

    View details for Web of Science ID 000264522400018

    View details for PubMedID 19252565

  • Fabrication and characterization of three-dimensional copper metallodielectric photonic crystals OPTICS EXPRESS Tal, A., Chen, Y., Williams, H. E., Rumpf, R. C., Kuebler, S. M. 2007; 15 (26): 18283–93

    View details for DOI 10.1364/OE.15.018283

    View details for Web of Science ID 000252045400088

    View details for PubMedID 19551126

  • Route to three-dimensional metallized microstructures using cross-linkable epoxide SU-8 CHEMISTRY OF MATERIALS Chen, Y., Tal, A., Kuebler, S. M. 2007; 19 (16): 3858–60

    View details for DOI 10.1021/cm0710812

    View details for Web of Science ID 000248439400002

  • Fabrication and characterization of three-dimensional silver-coated polymeric microstructures ADVANCED FUNCTIONAL MATERIALS Chen, Y., Tal, A., Torrance, D. B., Kuebler, S. M. 2006; 16 (13): 1739–44