A trachea-inspired bifurcated microfilter capturing viable circulating tumor cells via altered biophysical properties as measured by atomic force microscopy

Mechanism and Effects of Cellular Creep in a Microfluidic Filter

Biomicroparticles such as proteins, bacterium, and cells are known to be viscoelastic, which significantly affects their performance in microfluidic applications. However, the exact effects and the quantitative study of cellular viscoelastic creep within different applications remain unclear. In this study, the cellular-deforming evolution within a filter unit was studied using a multiphysics numerical model. A general cellular creep deformation process of viscoelastic particle trapping in pores was revealed. Two featured variables, namely, the maximum surface displacement and the volumetric strain, were identified and determined to quantitatively describe the evolution. The effects of flow conditions and physical characteristics of the microparticles were studied. Furthermore, a Giardia concentration experiment was conducted using an integrated hydraulic filtration system with a porous membrane. The experimental results agreed well with the numerical analysis, indicating that, compared to pure elastic particles, it is more difficult to release cellular material matters including cells, chemical synthetic particles, and microbes from trapping due to their time-accumulated creep deformation.

A fully automated primary neuron purification system using continuous centrifugal microfluidics

Progress in neurological research has experienced bottlenecks owing to the limited availability of purified primary neurons. Since neuronal cells are non-proliferative, it is necessary to obtain purified neurons from animal models or human patients for experimental work. However, currently available methods for purifying primary neurons are time-consuming (taking approximately 1 week), and suffer from insufficient viability and purity. Here, we report a method for rapid enrichment of neurons from the mouse embryonic dorsal root ganglion (DRG), using a fully-automated continuous centrifugal microfluidics (CCM) based neuron purification disc (NPD). Non-neuronal cells were removed via negative depletion by combining density gradient centrifugation and immunomagnetic separation. The CCM-NPD platform enables effective isolation of intact neurons within 13 min, which is approximately 800 times faster than the conventional chemical purification method. Furthermore, the neurons purified using the CCM-NPD platform showed better neurite growth, along with higher viability (93.5%) and purity (97.0%) after 1 week of culture, compared to the chemical purification method. Therefore, the proposed automated and rapid system yields purified DRG neurons with high viability and purity, while avoiding the use of harsh chemicals. We believe this system will significantly mitigate the shortage of purified primary neurons and advance neurological research.

Effects of Titanium Implant Combined with Nano-Indentation in the Vertical Control of Physiological Anchorage Spee’s Wire System Corrective Technology

In the current research, there was, in the vertical control of physiological anchorage spee’s wire system (PASS) technology, an investigation on the role of titanium implant technology in combination with nano-indentation experiment the present research. The human jaw was selected as the sample to be cut vertically, by doing do, to obtain a test slice of about 2 mm through a cutting machine following the nano-indentation test. The slice was frozen and preserved in normal saline and taken out during the test. 40 outpatients who underwent orthodontic therapy were chosen as the research objects and rolled in a random manner into a control category and an category of observation. Then, mechanical biological therapy (MBT) correction was conducted for the outpatients from the control category and PASS correction therapy based on the nano-indentation experiment was for outpatients from the category of observation. Following therapy, the therapy conditions of these two categories were compared, showing that the load was a fixed value and the depth of the indentation was increasing. Under the action of external force, the periodontal ligament might undergo elastic deformation, changing with duration. Dentition alignment duration, ligation duration, and deligation duration were less for participants in the observation group compared to those in the control category (P less than 0.05). The inclination between the longitudinal plane of the top central incisor and the sella juncture root point plane (UI-SN angle), the spacing between both the top mandibular teeth margin and the nasal root juncture molar seat point (UI-NA distance), and the angle between the upper and lower central incisor tooth axis and the NA connection (UI-NA angle) were all significantly less pronounced in the category of observation than in the control category (P less than 0.05). However, the angle of upper and lower central incisor long axis (UI-LI angle) from the category of observation was hugely greater than that of the control category (P less than 0.05). The value of dental arch width in the category of observation was smaller significantly than the value of the control category (P less than 0.05), and the changes in dental arch width were larger than those in the control category (P less than 0.05). Besides, the measured values of X-ray projections of outpatients from the category of observation were higher at of the control category (P less than 0.05). In conclusion, nano-indentation experiment can accurately match the equipment required in the therapy. The application of titanium materials combined with the vertical control of PASS correction technology can effectively alleviate the clinical symptoms of outpatients so as to improve the therapy effect.

Microslit on a chip: A simplified filter to capture circulating tumor cells enlarged with microbeads

Microchips are widely used to separate circulating tumor cells (CTCs) from whole blood by virtues of sophisticated manipulation for microparticles. Here, we present a chip with an 8 μm high and 27.9 mm wide slit to capture cancer cells bound to 3 μm beads. Apart from a higher purity and recovery rate, the slit design allows for simplified fabrication, easy cell imaging, less clogging, lower chamber pressure and, therefore, higher throughput. The beads were conjugated with anti-epithelial cell adhesion molecules (anti-EpCAM) to selectively bind to breast cancer cells (MCF-7) used to spike the whole blood. The diameter of the cell-bead construct was in average 23.1 μm, making them separable from other cells in the blood. As a result, the cancer cells were separated from 5 mL of whole blood with a purity of 52.0% and a recovery rate of 91.1%, and also we confirmed that the device can be applicable to clinical samples of human breast cancer patients. The simple design with microslit, by eliminating any high-aspect ratio features, is expected to reduce possible defects on the chip and, therefore, more suitable for mass production without false separation outputs.

Ultrasensitive label-free detection of circulating tumor cells using conductivity matching of two-dimensional semiconductor with cancer cell

The excellent conductivity matching of two-dimensional (2D) semiconductor nanomaterials (e.g. MoS₂) with cancer cell plays an important role in ultrasensitive label-free impedimetric detection of circulating tumor cells (CTC) (<1 cell/mL). Firstly, 2D semiconductor materials (e.g. 2D MoS₂) exfoliated by folic acid (FA) is used to construct MoS₂/FA-modified gold electrode (AuE/MoS₂/FA). Then, the fabricated electrode is applied for HeLa cell detection in a linear range from 1 to 10⁵ cell/mL with a detection limit of 0.43 cell/mL (S/N = 3). The detection mechanism of high sensitivity might be owing to the electric conductivity matching of MoS₂ (0.14 S/m) to cancer cell (0.13-0.23 S/m). A negligible conductivity change induced by cancer cell will produce a large impedance change of semiconductor electrode. Furthermore, HeLa cells dispersed in healthy blood samples are detected by suggested cytosensor in a linear range from 50 to 10⁵ cell/mL with a detection limit of 52.24 cell/mL (S/N = 2). Finally, we demonstrate that the cytosensor is capable of differentiating patients of cervical and liver cancers by the real CTC analysis from healthy control.

Cell-Free DNA in the Liquid Biopsy Context: Role and Differences Between ctDNA and CTC Marker in Cancer Management

Liquid biopsy is a new diagnostic concept to investigate the molecular features of solid tumors by blood, saliva, urine, and any other body fluids which show a source of potential biomarkers. In cancer patients, it is a simple and less invasive mean, representing a sustainable alternative to interrogate all tumor cells longitudinally, quantifying and characterizing the biological materials (DNAs, RNAs, proteins) which originate from cancer tissues. Circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) analysis from a simple blood draw received enormous attention for the related clinical research results. A rich scientific literature demonstrates that liquid biopsy is a valid instrument to assess the tumor biomarkers in real time and profile the cancer genotype in diagnostic and prognostic field, as well to quantify minimal residual disease, during patient follow-up. This could be a breakthrough for a companion diagnostic and personalized medicine. Liquid biopsy needs further implementation in the methodological aspects as well as cost-based assessment. The number of new molecular diagnostic assays increases day by day, but the standards for their adoption and clinical validation are still to be achieved.

Highly dense, optically inactive silica microbeads for the isolation and identification of circulating tumor cells

Efficient isolation of circulating tumor cells (CTCs) from whole blood is a major challenge for the clinical application of CTCs. Here, we report an efficient method to isolate CTCs from whole blood using highly dense and transparent silica microbeads. The surfaces of silica microbeads were fully covered with an antibody to capture CTCs, and blocked by zwitterionic moieties to prevent the non-specific adsorption of blood cells. Owing to the high density of the silica microbeads, the complexation of CTCs with silica microbeads resulted in the efficient sedimentation of CTC-microbead complexes, which enabled their discrimination from other blood cells in density gradient media. Model CTCs (MCF-7, HCC827, and SHP-77) with various levels of epithelial cell adhesion molecule (EpCAM) were isolated efficiently, especially those with low EpCAM expression (SHP-77). Moreover, the transparency of silica microbeads enabled CTCs to be clearly identified without interference caused by microbeads. The improved sensitivity resulted in increased CTC recovery from patient samples compared with the FDA-approved CellSearch system (14/15 using our method; 5/15 using the CellSearch system). These results indicate that the isolation method described in this report constitutes a powerful tool for the isolation of CTCs from whole blood, which has important applications in clinical practice.

Point-of-care (POC) devices by means of advanced MEMS

Microelectromechanical systems (MEMS) have become an invaluable technology to advance the development of point-of-care (POC) devices for diagnostics and sample analyses. MEMS can transform sophisticated methods into compact and cost-effective microdevices that offer numerous advantages at many levels. Such devices include microchannels, microsensors, etc., that have been applied to various miniaturized POC products. Here we discuss some of the recent advances made in the use of MEMS devices for POC applications.

Enrichment of circulating tumor cells using a centrifugal affinity plate system

Circulating tumor cells (CTCs) are defined as cells that have detached from a primary tumor and are circulating in the bloodstream. Their isolation and quantification is of great value for cancer prognoses and drug testing. Here, the development of a centrifugal affinity plate (CAP) system is described, in which centrifugal force and antibody-based capture are exploited to enrich CTCs on one plate and hematological cells on the other. The CAP is rotated to exert centrifugal force on the cells in a blood sample, quickly transporting them to the anti-epithelial adhesion molecule (EpCAM)-coated and anti-CD45-coated surface of the CAP to shorten the reaction time and increase the adhesion force between the tumor and blood cells and each antibody. The effect of a rotating process on cell capture was investigated, and the capture efficiency was demonstrated using blood samples from healthy donors spiked with human non-small cell lung cancer (NCI-H1650) and breast cancer (MCF-7) cells. The CAP system was capable of rapid isolation and identification of CTCs without the requirement for pretreatment of blood samples. Finally, the CAP system was tested to evaluate the detection efficiency of CTCs in the blood samples of breast cancer patients. The number of captured CTCs in only 1ml of blood varied from 6 to 10.

The roles of cellular nanomechanics in cancer

The biomechanical properties of cells and tissues may be instrumental in increasing our understanding of cellular behavior and cellular manifestations of diseases such as cancer. Nanomechanical properties can offer clinical translation of therapies beyond what are currently employed. Nanomechanical properties, often measured by nanoindentation methods using atomic force microscopy, may identify morphological variations, cellular binding forces, and surface adhesion behaviors that efficiently differentiate normal cells and cancer cells. The aim of this review is to examine current research involving the general use of atomic force microscopy/nanoindentation in measuring cellular nanomechanics; various factors and instrumental conditions that influence the nanomechanical properties of cells; and implementation of nanoindentation methods to distinguish cancer cells from normal cells or tissues. Applying these fundamental nanomechanical properties to current discoveries in clinical treatment may result in greater efficiency in diagnosis, treatment, and prevention of cancer, which ultimately can change the lives of patients.

A microchip filter device incorporating slit arrays and 3-D flow for detection of circulating tumor cells using CAV1-EpCAM conjugated microbeads

Circulating tumor cells (CTCs) are rare cells and the presence of these cells may indicate a poor prognosis and a high potential for metastasis. Despite highly promising clinical applications, CTCs have not been investigated thoroughly, due to many technical limitations faced in their isolation and identification. Current CTC detection techniques mostly take the epithelial marker epithelial cell adhesion molecule (EpCAM), however, accumulating evidence suggests that CTCs show heterogeneous EpCAM expression due to the epithelial-to-mesenchymal transition (EMT). In this study, we report that a microchip filter device incorporating slit arrays and 3-dimensional flow that can separate heterogeneous population of cells with marker for CTCs. To select target we cultured breast cancer cells under prolonged mammosphere culture conditions which induced EMT phenotype. Under these conditions, cells show upregulation of caveolin1 (CAV1) but down-regulation of EpCAM expression. The proposed device which contains CAV1-EpCAM conjugated bead has several tens of times increased throughput. More importantly, this platform enables the enhanced capture yield from metastatic breast cancer patients and obtained cells that expressed various EMT markers. Further understanding of these EMT-related phenotypes will lead to improved detection techniques and may provide an opportunity to develop therapeutic strategies for effective treatment and prevention of cancer metastasis.

Fully automated circulating tumor cell isolation platform with large-volume capacity based on lab-on-a-disc

Full automation with high purity for circulating tumor cell (CTC) isolation has been regarded as a key goal to make CTC analysis a "bench-to-bedside" technology. Here, we have developed a novel centrifugal microfluidic platform that can isolate the rare cells from a large volume of whole blood. To isolate CTCs from whole blood, we introduce a disc device having the biggest sample capacity as well as manipulating blood cells for the first time. The fully automated disc platform could handle 5 mL of blood by designing the blood chamber having a triangular obstacle structure (TOS) with lateral direction. To guarantee high purity that enables molecular analysis with the rare cells, CTCs were bound to the microbeads covered with anti-EpCAM to discriminate density between CTCs and blood cells and the CTCs being heavier than blood cells were only settled under a density gradient medium (DGM) layer. To understand the movement of CTCs under centrifugal force, we performed computational fluid dynamics simulation and found that their major trajectories were the boundary walls of the DGM chamber, thereby optimizing the chamber design. After whole blood was inserted into the blood chamber of the disc platform, size- and density-amplified cancer cells were isolated within 78 min, with minimal contamination as much as approximately 12 leukocytes per milliliter. As a model of molecular analysis toward personalized cancer treatment, we performed epidermal growth factor receptor (EGFR) mutation analysis with HCC827 lung cancer cells and the isolated cells were then successfully detected for the mutation by PCR clamping and direct sequencing.

Advances and critical concerns with the microfluidic enrichments of circulating tumor cells

Over the past two decades, circulating tumor cells (CTCs) have been widely recognized for their importance in clinical trials. While most enrichment methods for these cells have been conducted through the batch process due to their rarity in blood and the need for large sample volumes, the batch process leads to unavoidable cell loss. Given the heterogenetic features of CTCs, this cell loss may limit the validity of research that relies on the isolation of CTCs; such research includes cancer prognosis, diagnosis of minimal residual diseases, assessment of tumor sensitivity to anticancer drugs, and the personalization of anticancer therapies. Recent advances in microfluidic approaches have made it possible to enrich CTCs with a small degree of cell loss. In this review, we highlight several microfluidic-based positive and negative enrichment methods that are the subject of considerable research interest (e.g. EpCAM-dependent assay and EpCAM-independent assay) and suggest a microfluidic-based single cell analysis platform for the down-stream analysis of CTCs. We also discuss critical concerns and future directions for research.

A size amplified immune magnetic microbeads strategy in the rapid detection of circulating tumor cells

A size amplified immune magnetic microbeads strategy for the combined use of membrane filtration and immune-magnetic separation in CTC detection.