Capture and biological release of circulating tumor cells in pancreatic cancer based on peptide-functionalized silicon nanowire substrate

Nanomaterial-Based Strategies for Preventing Tumor Metastasis by Interrupting the Metastatic Biological Processes

Tumor metastasis is the primary cause of cancer-related deaths. The prevention of tumor metastasis has garnered notable interest and interrupting metastatic biological processes is considered a potential strategy for preventing tumor metastasis. The tumor microenvironment (TME), circulating tumor cells (CTCs), and premetastatic niche (PMN) play crucial roles in metastatic biological processes. These processes can be interrupted using nanomaterials due to their excellent physicochemical properties. However, most studies have focused on only one aspect of tumor metastasis. Here, the hypothesis that nanomaterials can be used to target metastatic biological processes and explore strategies to prevent tumor metastasis is highlighted. First, the metastatic biological processes and strategies involving nanomaterials acting on the TME, CTCs, and PMN to prevent tumor metastasis are briefly summarized. Further, the current challenges and prospects of nanomaterials in preventing tumor metastasis by interrupting metastatic biological processes are discussed. Nanomaterial-and multifunctional nanomaterial-based strategies for preventing tumor metastasis are advantageous for the long-term fight against tumor metastasis and their continued exploration will facilitate rapid progress in the prevention, diagnosis, and treatment of tumor metastasis. Novel perspectives are outlined for developing more effective strategies to prevent tumor metastasis, thereby improving the outcomes of patients with cancer.

Microfluidic systems for particle capture and release: A review

Microfluidic technology has emerged as a promising tool in various applications, including biosensing, disease diagnosis, and environmental monitoring. One of the notable features of microfluidic devices is their ability to selectively capture and release specific cells, biomolecules, bacteria, and particles. Compared to traditional bulk analysis instruments, microfluidic capture-and-release platforms offer several advantages, such as contactless operation, label-free detection, high accuracy, good sensitivity, and minimal reagent requirements. However, despite significant efforts dedicated to developing innovative capture mechanisms in the past, the release and recovery efficiency of trapped particles have often been overlooked. Many previous studies have focused primarily on particle capture techniques and their efficiency, disregarding the crucial role of successful particle release for subsequent analysis. In reality, the ability to effectively release trapped particles is particularly essential to ensure ongoing, high-throughput analysis. To address this gap, this review aims to highlight the importance of both capture and release mechanisms in microfluidic systems and assess their effectiveness. The methods are classified into two categories: those based on physical principles and those using biochemical approaches. Furthermore, the review offers a comprehensive summary of recent applications of microfluidic platforms specifically designed for particle capture and release. It outlines the designs and performance of these devices, highlighting their advantages and limitations in various target applications and purposes. Finally, the review concludes with discussions on the current challenges faced in the field and presents potential future directions.

Immunocapturing rare cells from blood: A simple and robust microsystem approach

Cell immunocapture microsystems are a fast-emerging field with several potential medical diagnostic applications. Isolation and quantification of circulating rare cells (CRCs) show great importance in the early stages of disease diagnostics and prognostics. Here, we present a simple and robust stop-flow microsystem (fabricated by a combination of glass microblasting and 3D printing) based on a planar antibody-coated surface that is effective in the immunocapture of the model as well as naturally occurring rare cells. A chip with a planar immunocapture channel working in the so-called stop-flow dynamic regime was designed to enable monitoring the efficiency of the cell capture by fluorescence microscopy. Up to 90% immunocapture efficiency of MCF-7 cells spiked into whole blood on CD326 antibody-coated planar surfaces was achieved. We discuss the role of the planar surface modifications, the influence of the set stop-flow dynamic conditions, and medium complexity on the efficiency of cell immunocapture. The presented results could be further employed in the design of microsystems for cell-size-independent isolation and identification of rare cells from blood.

Improving performance of cell imprinted PDMS by integrating boronate affinity and local post-imprinting modification for selective capture of circulating tumor cells from cancer patients

Efficient capture of circulating tumor cells (CTCs) from cancer patients is an important technique that may promote early diagnosis and prognosis monitoring of cancer. However, the existing systems have certain disadvantages, such as poor selectivity, low capture efficiency, consumption of antibodies, and difficulty in release of CTCs for downstream analysis. Herein, we fabricated an innovative PEGylated boronate affinity cell imprinted polydimethylsiloxane (PBACIP) for highly efficient capture of CTCs from cancer patients. The antibody-free PBACIP possessed hierarchical structure of imprinted cavities, which were inlaid with boronic acid modified SiO₂ nanoparticles (SiO₂@BA), so it could specifically capture target CTCs from biological samples due to the synergistic effect of boronate affinity and cell imprinting. Furthermore, PEGylation was accurately completed in the non-imprinted region by the template cells occupying the imprinted cavity, which not only retained the microstructure of original imprinted cavities, but also endowed PBACIP with hydrophilicity. The artificial PBACIP could efficiently capture human breast-cancer cells from biological sample. When 5 to 500 SKBR3 cells were spiked in 1 mL mice lysed blood, the capture efficiency reached 86.7 ± 11.5% to 96.2 ± 2.3%. Most importantly, the PBACIP was successfully used to capture CTCs from blood of breast cancer patients, and the captured CTCs were released for subsequent gene mutation analysis. The PBACIP can efficiently capture and release CTCs for downstream analysis, which provides a universal strategy toward individualized anti-tumor comprehensive treatments and has great potential in the future cell-based clinical applications.

Recent advances in micro-/nanostructure array integrated microfluidic devices for efficient separation of circulating tumor cells

Circulating tumor cells (CTCs) released from the primary tumor to peripheral blood are promising targets for liquid biopsies. Their biological information is vital for early cancer detection, efficacy assessment, and prognostic monitoring. Despite the tremendous clinical applications of CTCs, development of effective separation techniques are still demanding. Traditional separation methods usually use batch processing for enrichment, which inevitably destroy cell integrity and affect the complete information acquisition. Considering the rarity and heterogeneity of CTCs, it is urgent to develop effective separation methods. Microfluidic chips with precise fluid control at the micron level are promising devices for CTC separation. Their further combination with micro-/nanostructure arrays adds more biomolecule binding sites and exhibit unique fluid barrier effect, which significantly improve the CTC capture efficiency, purity, and sensitivity. This review summarized the recent advances in micro-/nanostructure array integrated microfluidic devices for CTC separation, including microrods, nanowires, and 3D micro-/nanostructures. The mechanisms by which these structures contribute to improved capture efficiency are discussed. Two major categories of separation methods, based on the physical and biological properties of CTCs, are discussed separately. Physical separation includes the design and preparation of micro-/nanostructure arrays, while chemical separation additionally involves the selection and modification of specific capture probes. These emerging technologies are expected to become powerful tools for disease diagnosis in the future.

Process simplification and structure design of parallelized microslit isolator for physical property-based capture of tumor cells

A facile, scalable, and highly efficient approach to physically capturing CTCs from blood samples has been developed using a microfluidic isolator with parallelized microslit channels.

Oxide nanowire microfluidics addressing previously-unattainable analytical methods for biomolecules towards liquid biopsy

Nanowire microfluidics using a combination of self-assembly and nanofabrication technologies is expected to be applied to various fields due to its unique properties. We have been working on the fabrication of nanowire microfluidic devices and the development of analytical methods for biomolecules using the unique phenomena generated by the devices. The results of our research are not just limited to the development of nanospace control with "targeted dimensions" in "targeted arrangements" with "targeted materials/surfaces" in "targeted spatial locations/structures" in microfluidic channels, but also cover a wide range of analytical methods for biomolecules (extraction, separation/isolation, and detection) that are impossible to achieve with conventional technologies. Specifically, we are working on the extraction technology "the cancer-related microRNA extraction method in urine," the separation technology "the ultrafast and non-equilibrium separation method for biomolecules," and the detection technology "the highly sensitive electrical measurement method." These research studies are not just limited to the development of biomolecule analysis technology using nanotechnology, but are also opening up a new academic field in analytical chemistry that may lead to the discovery of new pretreatment, separation, and detection principles.

Detection of circulating tumor cells: Advances and critical concerns

Metastasis is the main cause of cancer-related death and the major challenge in cancer treatment. Cancer cells in circulation are termed circulating tumor cells (CTCs). Primary tumor metastasis is likely due to CTCs released into the bloodstream. These CTCs extravasate and form fatal metastases in different organs. Analyses of CTCs are clarifying the biological understanding of metastatic cancers. These data are also helpful to monitor disease progression and to inform the development of personalized cancer treatment-based liquid biopsy. However, CTCs are a rare cell population with 1-10 CTCs per ml and are difficult to isolate from blood. Numerous approaches to detect CTCs have been developed based on the physical and biological properties of the cells. The present review summarizes the progress made in detecting CTCs.

Electrospun degradable Zn-Mn oxide hierarchical nanofibers for specific capture and efficient release of circulating tumor cells

Constructing biological affinity devices is considered as an effective strategy for isolating circulating tumor cells (CTCs), and electrospun nanofibers (ESNFs) have recently received attention. However, the current research focuses on polymer fibers, and fabricating stimuli-responsive inorganic nanofibers for cancer diagnosis and analysis is still challenging. In this work, Zn-Mn oxide nanofibers (ZnMnNFs) are used to capture and purify cancer cells after modification with specific antibodies. Then, the hierarchical nanofibers are degraded by reductive weak acid to release the captured cells efficiently without residues. Fusion of Zn and Mn, two transition metals, enhances the surface activity of oxides so that ZnMnNFs are easier to be degraded and modified. By using MCF-7 cancer cells, the cell capture efficiency of ZnMnNFs is up to 88.2%. Furthermore, by using citric acid, it is discovered that, by comparison with Mn oxide nanofibers, the cell release efficiency of ZnMnNFs is improved to 95.1% from 15.4%. In addition, the viability of released cells exceeds 90%. Lastly, the robustness of ZnMnNFs substrates is tested in peripheral blood from breast cancer patients (BCP) and colorectal cancer patients (CCP). Combined with fluorescence labeling, CTCs are confirmed to be isolated from all the clinical samples. This is the first trial of using ternary inorganic ESNFs for cancer cell capture. It is anticipated that the degradable ESNFs will provide biocompatible theranostic platforms and overcome the current limitations of cell release for high-precision gene analysis.

Nanotechnology-Assisted Isolation and Analysis of Circulating Tumor Cells on Microfluidic Devices

Circulating tumor cells (CTCs), a type of cancer cell that spreads from primary tumors into human peripheral blood and are considered as a new biomarker of cancer liquid biopsy. It provides the direction for understanding the biology of cancer metastasis and progression. Isolation and analysis of CTCs offer the possibility for early cancer detection and dynamic prognosis monitoring. The extremely low quantity and high heterogeneity of CTCs are the major challenges for the application of CTCs in liquid biopsy. There have been significant research endeavors to develop efficient and reliable approaches to CTC isolation and analysis in the past few decades. With the advancement of microfabrication and nanomaterials, a variety of approaches have now emerged for CTC isolation and analysis on microfluidic platforms combined with nanotechnology. These new approaches show advantages in terms of cell capture efficiency, purity, detection sensitivity and specificity. This review focuses on recent progress in the field of nanotechnology-assisted microfluidics for CTC isolation and detection. Firstly, CTC isolation approaches using nanomaterial-based microfluidic devices are summarized and discussed. The different strategies for CTC release from the devices are specifically outlined. In addition, existing nanotechnology-assisted methods for CTC downstream analysis are summarized. Some perspectives are discussed on the challenges of current methods for CTC studies and promising research directions.

Antibody-Free Hydrogel with the Synergistic Effect of Cell Imprinting and Boronate Affinity: Toward the Selective Capture and Release of Undamaged Circulating Tumor Cells

The selective and highly efficient capture of circulating tumor cells (CTCs) from blood and their subsequent release without damage are very important for the early diagnosis of tumors and for understanding the mechanism of metastasis. Herein, a universal strategy is proposed for the fabrication of an antibody-free hydrogel that has a synergistic effect by featuring microinterfaces obtained by cell imprinting and molecular recognition conferred by boronate affinity. With this artificial antibody, highly efficient capture of human hepatocarcinoma SMMC-7721 cells is achieved: as many as 90.3 ± 1.4% (n = 3) cells are captured when 1 × 10⁵ SMMC-7721 cells are incubated on a 4.5 cm² hydrogel, and 99% of these captured cells are subsequently released without any loss of proliferation ability. In the presence of 1000 times as many nontarget cells, namely, leukaemia Jurkat cells, the SMMC-7721 cells can be captured with an enrichment factor as high as 13.5 ± 3.2 (n = 3), demonstrating the superior selectivity of the artificial antibody for the capture of the targeted CTCs. Most importantly, the SMMC-7721 cells can be successfully captured even when spiked into whole blood, indicating the great promise of this approach for the further molecular characterization of CTCs.