Noninvasive Optical Isolation and Identification of Circulating Tumor Cells Engineered by Fluorescent Microspheres

Abstract

Circulating tumor cells (CTCs) are rare, meaning that current isolation strategies can hardly satisfy efficiency and cell biocompatibility requirements, which hinders clinical applications. In addition, the selected cells require immunofluorescence identification, which is a time-consuming and expensive process. Here, we developed a method to simultaneously separate and identify CTCs by the integration of optical force and fluorescent microspheres. Our method achieved high-purity separation of CTCs without damage through light manipulation and avoided additional immunofluorescence staining procedures, thus achieving rapid identification of sorted cells. White blood cells (WBCs) and CTCs are similar in size and density, which creates difficulties in distinguishing them optically. Therefore, fluorescent PS microspheres with high refractive index (RI) are designed here to capture the CTCs (PS-CTCs) and increase the average index of refraction of PS-CTCs. In optofluidic chips, PS-CTCs were propelled to the collection channel from the sample mixture, under the radiation of light force. Cells from the collection outlet were easily identified under a fluorescence microscope due to the fluorescence signals of PS microspheres. This method provides an approach for the sorting and identification of CTCs, which holds great potential for clinical applications in early diagnosis of disease.

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“…For diluted samples, effective collection by separating the target cells can significantly reduce the amount of fluid handled, for example, the accumulation of trace circulating tumor cells in the human peripheral blood [ 37 , 38 , 39 ]. The size of the circulating tumor cells in the peripheral blood samples of patients with early-stage cancer is around 14–25 μm [ 40 ], while the size of red blood cells with the highest content in the blood samples is about 6 μm [ 41 ].…”

Accelerated Healing of Infected Diabetic Wounds by a Dual-Layered Adhesive Film Cored with Microsphere-Loaded Hydrogel Composite Dressing

“…After crosslinking with a calcium chloride (CaCl 2 ) solution, the SA@bFGF microspheres were obtained by centrifugation and washed with light petroleum, pure isopropyl alcohol, and absolute ethyl alcohol in sequence. To determine the morphology of the microspheres, Alexa Fluor 647 was added to the water phase and evaluated using a Nikon TE300 fluorescence microscope . The final composition of the hydrogels composite was summarized in Supplementary Table 1.…”

“…To determine the morphology of the microspheres, Alexa Fluor 647 was added to the water phase and evaluated using a Nikon TE300 fluorescence microscope. 27 The final composition of the hydrogels composite was summarized in Supplementary Table 1. The working model is depicted in Figure 1A.…”

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“…Other techniques like opticallyinduced dielectrophoresis and channel design have also demonstrated potential for utilizing optical forces in CTC isolation. 68,79 However, the small disparity in optical constants between CTCs and WBCs adds complexity to the pre-treatment process and device fabrication, despite the high purity and recovery rates. 3.1.6 | Dielectrophoresis based CTC isolation…”

“… 67 By utilizing lasers in an optofluidic system, they attained high purity (>92%) and cell recovery rates (>90%) in CTC isolation. Other techniques like optically‐induced dielectrophoresis and channel design have also demonstrated potential for utilizing optical forces in CTC isolation 68,79 . However, the small disparity in optical constants between CTCs and WBCs adds complexity to the pre‐treatment process and device fabrication, despite the high purity and recovery rates.…”