In vivo photoacoustic monitoring using 700-nm region Raman source for targeting Prussian blue nanoparticles in mouse tumor model

Abstract

Photoacoustic imaging (PAI) is a noninvasive imaging tool to visualize optical absorbing contrast agents. Due to high ultrasonic resolution and superior optical sensitivity, PAI can be used to monitor nanoparticle-mediated cancer therapy. The current study synthesized Food and Drug Administration-approved Prussian blue (PB) in the form of nanoparticles (NPs) with the peak absorption at 712 nm for photoacoustically imaging tumor-bearing mouse models. To monitor PB NPs from the background tissue in vivo, we also developed a new 700-nm-region stimulated Raman scattering (SRS) source (pulse energy up to 200 nJ and repetition rate up to 50 kHz) and implemented optical-resolution photoacoustic microscopy (OR-PAM). The SRS-assisted OR-PAM system was able to monitor PB NPs in the tumor model with micrometer resolution. Due to strong light absorption at 712 nm, the developed SRS light yielded a two-fold higher contrast from PB NPs, in comparison with a 532-nm pumping source. The proposed laser source involved cost-effective and simple system implementation along with high compatibility with the fiber-based OR-PAM system. The study highlights the OR-PAM system in conjunction with the tunable-color SRS light source as a feasible tool to assist NP-mediated cancer therapy.

Quickly Alternating Green and Red Laser Source for Real-time Multispectral Photoacoustic Microscopy

“…When the pump light has sufficient power to induce SRS in the silica optical fiber, the pump light gets downshifted in frequency by 13.2 THz, depending on the Raman gain coefficient ( ) of silica. The Raman threshold power, , for the SRS effect to occur can be described by the following equation: [ 22 , 23 , 27 ] where is the Raman gain coefficient in the medium, is the effective fiber length, and is the effective core area. If of the Raman fiber is increased or is narrowed, for generating SRS can be lowered.…”

“…An increased number of SRS peaks up to the tenth Stokes order of 695 nm, with a pulse energy of up to 116 nJ, and a PRR of 300 kHz from a pump light of 532 nm was reported [ 22 ]. A 700 nm SRS laser, providing a pulse energy of up to 200 nJ and a PRR of 50 kHz, was used for photoacoustic imaging of Prussian blue nanoparticles in a mouse tumor [ 23 ]. Even though the SRS sources facilitated multispectral imaging, the real-time OR-PAM images at different excitation wavelengths, however, could not be obtained.…”

Nanotechnology: a promising method for oral cancer detection and diagnosis

“…These photoacoustic waves are being then transformed into photoacoustic images according to their arrival times after collected by an ultrasound transducer [ 69 , 70 ]. The ultrasound provides high spatial resolution for structural phenotyping and is a useful tool for assessing lymph nodes following a radical surgery [ 71 , 72 ]. Consequently, the optical contrast can be significantly improved while maintaining the high spatial resolution of ultrasound [ 73 ].…”

Photoacoustic Imaging-Guided Photothermal Therapy with Tumor-Targeting HA-FeOOH@PPy Nanorods

“…We have recently build the PAM system to monitor the presence of nanoparticles in mouse tumor model 61 . The PAM system used a single-mode optical fiber with polarization-maintaining (PM-S405-XP) to deliver light from a diode pumped passively Q-switched solid state laser of 532 nm (SPOT-10-100-532).…”