Dr. Vijay Raghavan Profile

Dr. Vijay Raghavan

Postdoctoral Researcher at Univ of Galway

SPIE Involvement:

Author

Area of Expertise:

Nanotechnology , Biomedical Optical Imaging , Photoacoustic/Ultrasound Imaging , Nanoplasmonics , Optical Modelling , Photodynamic/Photothermal Therapy

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Company Website

Vijay played a key part in proposal drafting and coordinating research collaboration among multiple partners in Europe for acquiring the European Research Council funding (EUR 6M) in Jan 2018 for STARSTEM (https://www.linkedin.com/feed/update/urn:li:activity:6336567983510560768). Extension of his PhD and post-PhD research work on light concentration effects in photonic nanostructures, STARSTEM will investigate and optimise the detection, tracking and monitoring of stem cells and exosome-mediated therapy for osteoarthritis by using SPION conjugated nanostars as contrast agent for dual-modal in vivo MRI and PA imaging to acquire anatomical and functional information, respectively, to investigate the efficacy of stem cells and exosomes-mediated regenerative process.Vijay’s current interest also involves using nanoparticle contrast agent for NIR Photothermal Optical Coherence Tomography (PT-OCT). Objectives of this project includes, (a) optothermal simulations of NIR gold nanoparticles to investigate nanoparticles’ photothermal efficacy by finite element method using COMSOL Multiphysics and DEVICE, and (b) analysis of phase change due to photothermal property of gold nanoparticles embedded phantoms using Photothermal Optical Coherence Tomography (PT-OCT). Vijay received his Ph.D. in Applied Physics (Nanobiophotonics) in 2016 from NUI, Galway specialising in developing nanoprobes for multimodal imaging and therapy of cancer. He earlier obtained his Master’s degree from Western Sydney University, Australia in Biotechnology specialising in developing novel fluorescent sensor to detect DNA amplification in real-time polymerase chain reaction (RT-PCR).

Proceedings Article | 15 March 2018 Presentation

Plasmonic gold nanostars for biomedical imaging and theranostic applications (Conference Presentation)

Vijay Raghavan, Hrebesh Molly Subhash, Malini Olivo, Martin Leahy

Proceedings Volume 10493, 104930V (2018) https://doi.org/10.1117/12.2296712

KEYWORDS: Gold, Plasmonics, Biomedical optics, Near infrared, Nanoparticles, Photoacoustic imaging, Tumors, Continuous wave operation, Diagnostics, Image resolution

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Nanoparticle contrast agents for targeted imaging have widespread diagnostic applications with cellular resolution, specificity and selectivity for visualization and assessment of various disease processes. Of particular interest are gold nanoparticles owing to the tunability of the localised surface plasmon resonance (LSPR) and its relative inertness. Synthesizing gold nanoprobes in the near infrared (NIR) region is of particular interest in developing nanosensors due to the minimal light attenuation from biomolecules. The ability of plasmonic gold nanostars (GNS), with novel shape-dependent dual LSPR, to elicit signal contrast at NIR wavelengths is described here for multiple biomedical modalities. First, the surface enhanced Raman scattering (SERS) capability of these dual plasmonic GNS has been demonstrated to elicit high SERS enhancement factor (EF) of 2 x 10e7 with 785 nm excitation and the potential to elicit the highest SERS EF ever reported for gold nanoparticles, with further longer wavelength excitations at and beyond 1064 nm. We have also demonstrated the longer wavelength contrast imaging capability of GNS with photoacoustic imaging (PAI) and for photothermal therapy (PTT). GNS possess unique structural characteristics that impart superior optical properties resulting in higher photothermal efficiency. The photothermal capability of GNS was demonstrated in vivo with localized temperature rise of 9℃ in tumors when irradiated with a 1064 nm CW laser that resulted in significant tumor cell death. Since photothermal conversion is the optical process responsible for eliciting PA contrast and for PTT, this development represents a novel theranostic substrate to be used at 1064 nm excitation, a longer wavelength than the conventional clinical range. The ability of GNS to elicit signal contrast at NIR wavelengths has also been demonstrated for photothermal optical coherence tomography (PT-OCT). When irradiated with a 1064 nm continuous wave laser, GNS elicited photothermal contrast well beyond 2 mm, displaying great potential for deep tissue imaging. We have also recently obtained a European Commission grant worth €5.98M on developing, demonstrating and validating a novel GNS enhanced photoacoustic imaging platform which will be capable of tracking mesenchymal stem cells (MSC) and MSC-derived exosomes, at unprecedented depth and sensitivity.

Proceedings Article | 3 March 2014 Paper

Dual plasmonic gold nanoparticles for multispectral photoacoustic imaging application

Vijay Raghavan, Hrebesh Subhash, Aedán Breathnach, Martin Leahy, Peter Dockery, Malini Olivo

Proceedings Volume 8943, 89434J (2014) https://doi.org/10.1117/12.2042079

KEYWORDS: Absorption, Gold, Nanoparticles, Plasmons, Photoacoustic imaging, Multispectral imaging, Near infrared, Silver, Plasmonics, Photoacoustic spectroscopy

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