In vivo multispectral photoacoustic and photothermal flow cytometry with multicolor dyes: A potential for real‐time assessment of circulation, dye‐cell interaction, and blood volume

Abstract

Recently, photoacoustic (PA) flow cytometry (PAFC) has been developed for in vivo detection of circulating tumor cells and bacteria targeted by nanoparticles. Here, we propose multispectral PAFC with multiple dyes having distinctive absorption spectra as multicolor PA contrast agents. As a first step of our proof-of-concept, we characterized high-speed PAFC capability to monitor the clearance of three dyes (ICG, MB, and TB) in an animal model in vivo and in real time. We observed strong dynamic PA signal fluctuations, which can be associated with interactions of dyes with circulating blood cells and plasma proteins. PAFC demonstrated enumeration of circulating red and white blood cells labeled with ICG and MB, respectively, and detection of rare dead cells uptaking TB directly in bloodstream. The possibility for accurate measurements of various dye concentrations including CV and BG were verified in vitro using complementary to PAFC photothermal (PT) technique and spectrophotometry under batch and flow conditions. We further analyze the potential of integrated PAFC/PT spectroscopy with multiple dyes for rapid and accurate measurements of circulating blood volume without a priori information on hemoglobin content, which is impossible with existing optical techniques. This is important in many medical conditions including surgery and trauma with extensive blood loss, rapid fluid administration, transfusion of red blood cells. The potential for developing a robust clinical PAFC prototype that is, safe for human, and its applications for studying the liver function are further highlighted.

Photoacoustic flow cytometry

“…As most contrast agents have intrinsic optical absorption, PAFC is an almost ideal tool for real-time, label-free monitoring of their pharmacokinetics. We demonstrated PAFC's capability to monitor the circulation lifetime of NPs (e.g., GNRs, GNTs, MNPs), dyes (ICG, Methylene Blue [MB], and Trypan Blue [TB], Evans Blue, and Lymphazurine), microbubbles, normal blood cells, and CTCs (melanoma, breast cancer, squamous carcinoma, pancreatic cancer) using a laser with different wavelengths [11,15,28–30,33,38,40]. Circulating objects can be detected when PA signals from them are above the blood background associated preferentially with absorption of RBCs (Fig.…”

Nanoparticle delivery for metastatic breast cancer

“…Human clinical prototype photoacoustic flow cytometers are currently under development which hold the promise of enabling translation of nanoparticle mediated detection and destruction of circulating tumor cells in breast cancer patients (Fig. 2) [69].…”

“…Clinical prototype of an in vivo photoacoustic flow cytometer that could be used to detect circulating nanoparticles.Reproduced with permission from Cytometry Part A[69].…”

Fast Screening Techniques for Neurotoxigenic Substances and Other Toxicants and Pollutants Based on Thermal Lensing and Microfluidic Chips

“…Owing to its inherently high sensitivity, TLS enables measurements of optical absorbances lower than 10 -6 . 7 Other important characteristics of TLS include the possibility of probing very small (sub-picoliter) [23][24][25][26][27][28][29] TLS and photothermal instruments do not offer the possibility of simultaneous multiwave measurements or rapid spectral scanning, such as provided by diode-array spectrophotometric detectors (DAD). TLS is therefore mainly applied as a detection technique for separation methods, like high-performance liquid chromatography (HPLC), capillary electrophoresis (CE), and ion chromatography (IC), which provide the required selectivity.…”