Enhanced capture and release of circulating tumor cells using hollow glass microspheres with a nanostructured surface

Polymer Microspheres and Their Application in Cancer Diagnosis and Treatment

Cancer is a significant global public health issue with increasing morbidity and mortality rates. To address this challenge, novel drug carriers such as nano-materials, liposomes, hydrogels, fibers, and microspheres have been extensively researched and utilized in oncology. Among them, polymer microspheres are gaining popularity due to their ease of preparation, excellent performance, biocompatibility, and drug-release capabilities. This paper categorizes commonly used materials for polymer microsphere preparation, summarizes various preparation methods (emulsification, phase separation, spray drying, electrospray, microfluidics, and membrane emulsification), and reviews the applications of polymer microspheres in cancer diagnosis, therapy, and postoperative care. The current status and future development directions of polymer microspheres in cancer treatment are analyzed, highlighting their importance and potential for improving patient outcomes.

Bioorthogonal Microbubbles with Antifouling Nanofilm for Instant and Suspended Enrichment of Circulating Tumor Cells

Integrating clinical rare cell enrichment, culture, and single-cell phenotypic profiling is currently hampered by the lack of competent technologies, which typically suffer from weak cell-interface collision affinity, strong nonspecific adsorption, and the potential uptake. Here, we report cells-on-a-bubble, a bioinspired, self-powered bioorthogonal microbubble (click bubble) that leverages a clickable antifouling nanointerface and a DNA-assembled sucker-like polyvalent cell surface, to enable instant and suspended isolation of circulating tumor cells (CTCs) within minutes. Using this biomimetic engineering strategy, click bubbles achieve a capture efficiency of up to 98%, improved by 20% at 15 times faster over their monovalent counterparts. Further, the buoyancy-activated bubble facilitates self-separation, 3D suspension culture, and in situ phenotyping of the captured single cancer cells. By using a multiantibody design, this fast, affordable micromotor-like click bubble enables suspended enrichment of CTCs in a cohort (n = 42) across three cancer types and treatment response evaluation, signifying its great potential to enable single-cell analysis and 3D organoid culture.

Floating Immunomagnetic Microspheres for Highly Efficient Circulating Tumor Cell Isolation under Facile Magnetic Manipulation

Among circulating tumor cell enrichment strategies, immunomagnetic beads (IMBs) have received great attention due to their excellent performance. However, traditional strategies using IMBs normally require an additional mechanical stirring device to fully mix the IMBs and specimens, and this step may cause mechanical cellular damage. In this study, by changing the architecture and motion trajectory control strategy of the IMBs, floating immunomagnetic microspheres (FIMMs) and their matching rotary magnetic manipulation device were proposed to achieve highly efficient CTC capture under a cell-friendly condition. Generally, the FIMMs were prepared through layer-by-layer assembly of the individual functional components, and their stress state governed by either buoyancy or magnetic force was tuned by the rotary magnetic manipulation device. Consequently, recognition of FIMMs and target cells as well as CTC recovery can be simply realized through external magnetic manipulation. Accordingly, satisfactory enrichment efficiencies for CTCs with varied epithelial expression levels were obtained as 92.93 ± 3.23% for MCF-7, 79.93 ± 3.31% for A549, and 92.57 ± 5.22% for HepG2. Besides, an extremely low detection limitation of 5 cells mL^-1 can be achieved from complex sample conditions, even the whole blood. In addition, FIMMs successfully enriched 23-56 CTCs from 1.5 mL of blood samples from cancer patients.

Natural Biointerface Based on Cancer Cell Membranes for Specific Capture and Release of Circulating Tumor Cells

Circulating tumor cells (CTCs) are an important part of liquid biopsy as they represent a potentially rich source of information for cancer diagnosis, monitoring, prognosis, and treatment guidance. It has been proved that the nanotopography interaction between cells and the surface of CTC detection platforms can significantly improve the capture efficiency of CTCs, whereas many mature nanostructure substrates have been developed based on chemistry materials. In this work, a natural biointerface with unique biological properties is fabricated for efficient isolation and nondestructive release of CTCs from blood samples using the cancer cell membranes. The cell membrane interfaces are proved to have a good antiadhesion property for nonspecific cells because of their own electronegativity. A natural surface nanostructure is provided by the cancer cell membrane to nicely match with the surface nanotopography of CTCs. Bovine serum albumin (BSA) as a linker and DNA aptamer against the epithelial cell adhesion molecule (EpCAM) as a specific affinity molecule are then introduced onto the cell membrane interfaces to achieve the highly efficient and specific capture of CTCs. Finally, the captured target cells can be intactly released from the substrate using the complementary DNA sequence with controlling the incubation time. This study provides a smart strategy in the development of a natural biological interface for the isolation and release of CTCs with high purity.

[Preliminary Study on Detection of Circulating Tumor Cells in Lung Cancer by EGFR/Vimentin/Folic Acid Magnetic Sphere]

背景与目的

循环肿瘤细胞(circulating tumor cell, CTC)在肺癌的筛查及预后方面发挥着重要的作用, 但较低的CTC分离效率和特异性对其临床应用有着明显的制约, 本研究旨在探讨非小细胞肺癌(non-small cell lung cancer, NSCLC)患者CTC的新型高效分离方法, 以期达到对NSCLC的早期诊断的目的。

方法

采用薄膜法制备表皮生长因子受体(epidermal growth factor receptor, EGFR)、波形蛋白(Vimentin)和叶酸(folic acid, FA)三种免疫脂质磁球, 表征后通过细胞系进行分选方案的探索, 构建对NSCLC CTC的最优分选方案, 初步研究了其在临床上的应用价值。

结果

EGFR、Vimentin和FA磁球磁球单独和联合使用对肺癌细胞株的平均捕获效率分别为78.0%、79.0%、82.0%和91.0%;在60例肺癌患者中, 以每7.5 mL血液2个CTC为cutoff值, EGFR、Vimentin、FA磁球单独和联合使用阳性率分别为65.0%、33.3%、93.3%和100.0%, 同时发现联合使用三种磁球检出的CTC数量与临床分期具有相关性(P < 0.05)。

结论

联合使用三种磁球可以分离EGFR+、Vimentin+和FA+表达且形态完整的CTC, 有利于的CTC相关下游分析, 本研究提供了一种提高NSCLC CTC捕获效率的新方法, 且验证了捕获的CTC计数方法可用于肺癌的辅助诊断。

Nano Meets Micro-Translational Nanotechnology in Medicine: Nano-Based Applications for Early Tumor Detection and Therapy

Nanomaterials have great potential for the prevention and treatment of cancer. Circulating tumor cells (CTCs) are cancer cells of solid tumor origin entering the peripheral blood after detachment from a primary tumor. The occurrence and circulation of CTCs are accepted as a prerequisite for the formation of metastases, which is the major cause of cancer-associated deaths. Due to their clinical significance CTCs are intensively discussed to be used as liquid biopsy for early diagnosis and prognosis of cancer. However, there are substantial challenges for the clinical use of CTCs based on their extreme rarity and heterogeneous biology. Therefore, methods for effective isolation and detection of CTCs are urgently needed. With the rapid development of nanotechnology and its wide applications in the biomedical field, researchers have designed various nano-sized systems with the capability of CTCs detection, isolation, and CTCs-targeted cancer therapy. In the present review, we summarize the underlying mechanisms of CTC-associated tumor metastasis, and give detailed information about the unique properties of CTCs that can be harnessed for their effective analytical detection and enrichment. Furthermore, we want to give an overview of representative nano-systems for CTC isolation, and highlight recent achievements in microfluidics and lab-on-a-chip technologies. We also emphasize the recent advances in nano-based CTCs-targeted cancer therapy. We conclude by critically discussing recent CTC-based nano-systems with high therapeutic and diagnostic potential as well as their biocompatibility as a practical example of applied nanotechnology.

Nanoparticle modification of microfluidic cell separation for cancer cell detection and isolation

We present a nanoparticle surface modification approach to improve the microfluidic performance in detecting cancer cells. Multiple cancer cell lines were included in this work, and the capture ability of the chip with surface modification reached a significant increase.

Aptamer-Functionalized and Gold Nanoparticle Array-Decorated Magnetic Graphene Nanosheets Enable Multiplexed and Sensitive Electrochemical Detection of Rare Circulating Tumor Cells in Whole Blood

The identification and monitoring of circulating tumor cells (CTCs) in human blood plays a pivotal role in the convenient diagnosis of different cancers. However, it remains a major challenge to monitor these CTCs because of their extremely low abundance in human blood. Here, we describe the synthesis of a new aptamer-functionalized and gold nanoparticle (AuNP) array-decorated magnetic graphene nanosheet recognition probe to capture and isolate rare CTCs from human whole blood. In addition, by employing the aptamer/electroactive species-loaded AuNP signal amplification probes, multiplexed electrochemical detection of these low levels of CTCs can be realized. The incubation of the probes with the sample solutions containing the target CTCs can lead to the efficient separation of the CTCs and result in the generation of two distinct voltammetric peaks on a screen-printed carbon electrode, whose potentials and current intensities, respectively, reflect the identity and number of CTCs for the multiplexed detection of the Ramos and CCRF-CEM cells with detection limits down to 4 and 3 cells mL^-1. With the successful demonstration of the concept, further extension of the developed sensing strategy for the determination of various CTCs in human whole blood for the screening of different cancers can be envisioned in the near future.

Effective reduction of non-specific binding of blood cells in a microfluidic chip for isolation of rare cancer cells

The high purity of target cells enriched from blood samples plays an important role in the clinical detection of diseases. However, non-specific binding of blood cells in the isolated cell samples can complicate downstream molecular and genetic analysis. In this work, we report a simple solution to non-specific binding of blood cells by modifying the surface of microchips with a multilayer nanofilm, with the outmost layer containing both PEG brushes for reducing blood cell adhesion and antibodies for enriching target cells. This layer-by-layer (LbL) polysaccharide nanofilm was modified with neutravindin and then conjugated with a mixture of biotinylated PEG molecules and biotinylated antibodies. Using EpCAM-expressing and HER2-expressing cancer cells in blood as model platforms, we were able to dramatically reduce the non-specific binding of blood cells to approximately 1 cell per mm2 without sacrificing the high capture efficiency of the microchip. To support the rational extension of this approach to other applications for cell isolation and blood cell resistance, we conducted extensive characterization on the nanofilm formation and degradation, antifouling with PEG brushes and introducing functional antibodies. This simple, yet effective, approach can be applied to a variety of microchip applications that require high purity of sample cells containing minimal contamination from blood cells.

Erythrocyte-derived vesicles for circulating tumor cell capture and specific tumor imaging

The precise diagnosis of cancer remains a great challenge; therefore, it is our research interest to develop safe, tumor-specific reagents. In this study, we designed nanovesicles derived from erythrocyte membranes; the nanovesicles are capable of recognizing tumor cells for both circulating tumor cell (CTC) capture and tumor imaging. The tumor-targeting molecules folic acid (FA) and fluorescein Cy5 were modified on the nanovesicle surface. The developed nanovesicles exhibit excellent tumor targeting ability both in vitro and in vivo for CTC capture and in tumor imaging. Compared with traditional immunomagnetic beads, the proposed nanovesicles are capable of avoiding non-specific adsorption as a derivative of red blood cells. Combined with a non-invasive means of micromanipulation, the nanometer-sized vesicles show a high purity of CTC capture (over 90%). In vivo, the nanovesicles can also be employed for efficient tumor imaging without obvious toxicity and side effects. In brief, the nanovesicles prepared herein show potential clinical application for integrated diagnosis in vitro and in vivo.

Microfluidic preparation, shrinkage, and surface modification of monodispersed alginate microbeads for 3D cell culture

Functionalized alginate microbeads (MB) have been widely used for three-dimensional (3D) culture of cells and creating biomimetic tissue models. However, conventional methods for preparing these MB suffer from poor polydispersity, due to coalescence of droplets during the gelation process and post-aggregation. It remains an immense challenge to prepare alginate MB with narrow size distribution and uniform shape, especially when their diameters are similar to the size of cells. In this work, we developed a simple method to produce monodispersed, cell-size alginate MB through microfluidic emulsification, followed by a controlled shrinkage process and gelation in mineral oil with low concentration of calcium ion (Ca²⁺). During the gelation process caused by the diffusion of Ca²⁺ from the oil to water phase, a large amount of satellite droplets with sub-micrometer sizes was formed at the water/oil interface. As a result, each original droplet was transformed to one shrunken-MB with much smaller size and numerous submicron-size satellites. To explore the feasibility of the shrunken-MB for culturing with cells, we have successfully modified a variety of polymer nanofilms on MB surfaces using a layer-by-layer assembly approach. Finally, the nanofilm-modified MB was applied to a 3D culture of GFP-expressing fibroblast cells and demonstrated good biocompatibility.

Cell-size alginate microbeads for 3D cell culture were prepared by microfluidic emulsification and controlled shrinkage, followed by nanofilm modification.

Size-matching hierarchical micropillar arrays for detecting circulating tumor cells in breast cancer patients' whole blood

Circulating tumor cells (CTCs) are important markers for cancer diagnosis and treatment, but it is still a challenge to recognize and isolate CTCs because they are very rare in the blood. To selectively recognize CTCs and improve the capture efficiency, micro/nanostructured substrates have been fabricated for this application; however the size of CTCs is often ignored in designing and engineering micro/nanostructured substrates. Herein, a spiky polymer micropillar array is fabricated for capturing CTCs with high efficiency. The surface of the micropillar is cactus-like, and is composed of nanospikes. This hierarchical polymer array is designed according to the size of CTCs, which allows for more interactions of the CTCs with the array by setting the size of gaps among the micropillars to match with the CTCs. This polymer array is created by molding on an ordered silicon array, and then it is coated with an antiepithelial cell adhesion molecule antibody (anti-EpCAM). After co-culture with MCF-7 cells for 45 min, the capture efficiency of this array for CTCs is up to 91% ± 2%. Moreover, the anti-EpCAM modified polymer micropillar arrays present an excellent capacity to isolate CTCs from the whole blood samples of breast cancer patients. This study may provide a new concept for capturing target cells by designing and engineering micro/nanostructured substrates according to the size of target cells.