On-Chip Multicolor Photoacoustic Imaging Flow Cytometry

Abstract

On-chip imaging flow cytometry has been widely used in cancer biology, immunology, microbiology, and drug discovery. Pure optical imaging combined with flow cytometry to derive chemical, structural, and morphological features of cells provides systematic insights into biological processes. However, due to the high concentration and strong optical attenuation of red blood cells, preprocessing is necessary for optical flow cytometry while dealing with whole blood. In this study, we develop an on-chip photoacoustic imaging flow cytometry (PAIFC), which combines multicolor high-speed photoacoustic microscopy and microfluidics for cell imaging. The device employs a micro-optical scanner to achieve a miniaturized outer size of 30 × 17 × 24 mm3 and ultrafast cross-sectional imaging at a frame rate of 1758 Hz and provides lateral and axial resolutions of 2.2 and 33 μm, respectively. Using a multicolor strategy, PAIFC is able to differentiate cells labeled by external contrast agents, detect melanoma cells with an endogenous contrast in whole blood, and image melanoma cells in blood samples from tumor-bearing mice. The results suggest that PAIFC has sufficient sensitivity and specificity for future cell-on-chip applications.

The Fusion of Microfluidics and Optics for On-Chip Detection and Characterization of Microalgae

“…Song et al developed a microfluidic photoacoustic microscopy technique that realized both 2-dimensional (2D) and 3-dimensional visualization of the droplets with high throughput [133]; the lateral resolution of this technique can be enhanced to reach an optical diffraction limit (~5 µm). Subsequently, the opto-acoustic-fluidic-based technology was used for the detection and identification of red blood cells and circulating primitive cells [139]. However, to the best of our knowledge, only limited studies have applied photoacoustic in single plant cells [140,141]; considering the rich content and types of pigments inside microalgae cells, we believe that microfluidic-based photoacoustic microscopy must have a variety of applications in microalgae identification, cell viability estimation and qualitative analysis of pigments or lipid.…”

Multicolor Photoacoustic Volumetric Imaging of Subcellular Structures

“…As a hybrid imaging modality based on photoacoustic effect, photoacoustic imaging (PAI) is a well-established method in both clinical and fundamental studies due to the rich optical contrast generated by the specific extinction coefficient and Grüneisen parameter of chromophores. − Optical resolution photoacoustic microscopy (OR-PAM), featuring high lateral resolution defined by the optical diffraction limit, has been widely used in observing objects from organelles to organs. , Especially, OR-PAM shows great potential in imaging cellular and subcellular structures . The detection of red blood cell morphology, observation of lipids and proteins in cells, and visualization of subcellular structures from a histopathological section has been demonstrated. − In addition, OR-PAM combined with microfluidics has achieved the imaging and manipulation of moving cells in microfluidic chips. ,, For cellular and subcellular structures observation, compared with bright-field microscopy, OR-PAM provides richer optical contrast and better spatial resolving capability.…”

“…As a hybrid imaging modality based on photoacoustic effect, photoacoustic imaging (PAI) is a well-established method in both clinical and fundamental studies due to the rich optical contrast generated by the specific extinction coefficient and Grüneisen parameter of chromophores. − Optical resolution photoacoustic microscopy (OR-PAM), featuring high lateral resolution defined by the optical diffraction limit, has been widely used in observing objects from organelles to organs. , Especially, OR-PAM shows great potential in imaging cellular and subcellular structures . The detection of red blood cell morphology, observation of lipids and proteins in cells, and visualization of subcellular structures from a histopathological section has been demonstrated. − In addition, OR-PAM combined with microfluidics has achieved the imaging and manipulation of moving cells in microfluidic chips. ,, For cellular and subcellular structures observation, compared with bright-field microscopy, OR-PAM provides richer optical contrast and better spatial resolving capability. Both phase imaging and stimulated Raman scattering imaging have been widely applied to visualize cellular and subcellular structures, where phase imaging reveals the difference in refractive index between subcellular structures, , and stimulated Raman scattering imaging presents the mapping of chemical components in cells. , Besides a restricted experimental environment, complicated systemic designs/reconstruction methods and severe optical scattering and attenuation inside biological tissues hinder them from differentiating subcellular structures in turbid media and in vivo .…”

Significantly amplified photoacoustic effect for silica-coated gold nanoparticles by interface heat transfer mechanisms

“…1,2 PA effect has found wide applications including in the biomedical field since it reveals anatomical, molecular, functional, metabolic, and mechanical information of the cells and tissue. [3][4][5][6][7][8] Exogenous PA contrast agents are often utilized to provide information on cellular and molecular events. [9][10][11][12] To achieve an accurate diagnosis, the high optical-to-acoustic conversion efficiency is crucial for exogenous PA contrast agents.…”