Label-free enrichment of rare unconventional circulating neoplastic cells using a microfluidic dielectrophoretic sorting device

Recent Advances in Dielectrophoretic Manipulation and Separation of Microparticles and Biological Cells

Dielectrophoresis (DEP) is an advanced microfluidic manipulation technique that is based on the interaction of polarized particles with the spatial gradient of a non-uniform electric field to achieve non-contact and highly selective manipulation of particles. In recent years, DEP has made remarkable progress in the field of microfluidics, and it has gradually transitioned from laboratory-scale research to high-throughput manipulation in practical applications. This paper reviews the recent advances in dielectric manipulation and separation of microparticles and biological cells and discusses in detail the design of chip structures for the two main methods, direct current dielectrophoresis (DC-DEP) and alternating current dielectrophoresis (AC-DEP). The working principles, technical implementation details, and other improved designs of electrode-based and insulator-based chips are summarized. Functional customization of DEP systems with specific capabilities, including separation, capture, purification, aggregation, and assembly of particles and cells, is then performed. The aim of this paper is to provide new ideas for the design of novel DEP micro/nano platforms with the desired high throughput for further development in practical applications.

Efficient separation of large particles and giant cancer cells using an isosceles trapezoidal spiral microchannel

Polyploid giant cancer cells (PGCCs) contribute to the genetic heterogeneity and evolutionary dynamics of tumors. Their size, however, complicates their isolation from mainstream tumor cell populations. Standard techniques like fluorescence-activated cell sorting (FACS) rely on fluorescent labeling, introducing potential challenges in subsequent PGCC analyses. In response, we developed the Isosceles Trapezoidal Spiral Microchannel (ITSμC), a microfluidic device optimizing the Dean drag force (FD) and exploiting uniform vortices for enhanced separation. Numerical simulations highlighted ITSμC's advantage in producing robust FD compared to rectangular and standard trapezoidal channels. Empirical results confirmed its ability to segregate larger polystyrene (PS) particles (avg. diameter: 50 μm) toward the inner wall, while directing smaller ones (avg. diameter: 23 μm) outward. Utilizing ITSμC, we efficiently isolated PGCCs from doxorubicin-resistant triple-negative breast cancer (DOXR-TNBC) and patient-derived cancer (PDC) cells, achieving outstanding purity, yield, and viability rates (all greater than 90%). This precision was accomplished without fluorescent markers, and the versatility of ITSμC suggests its potential in differentiating a wide range of heterogeneous cell populations.

A Review of Research Progress in Microfluidic Bioseparation and Bioassay

With the rapid development of biotechnology, the importance of microfluidic bioseparation and bioassay in biomedicine, clinical diagnosis, and other fields has become increasingly prominent. Microfluidic technology, with its significant advantages of high throughput, automated operation, and low sample consumption, has brought new breakthroughs in the field of biological separation and bioassay. In this paper, the latest research progress in microfluidic technology in the field of bioseparation and bioassay is reviewed. Then, we focus on the methods of bioseparation including active separation, passive separation, and hybrid separation. At the same time, the latest research results of our group in particle separation are introduced. Finally, some application examples or methods for bioassay after particle separation are listed, and the current challenges and future prospects of bioseparation and bioassay are discussed.

Automated Image Analysis for Characterization of Circulating Tumor Cells and Clusters Sorted by Magnetic Levitation

Magnetic levitation-based sorting technologies have revolutionized the detection and isolation of rare cells, including circulating tumor cells (CTCs) and circulating tumor cell clusters (CTCCs). Manual counting and quantification of these cells are prone to time-consuming processes, human error, and inter-observer variability, particularly challenging when heterogeneous cell types in 3D clusters are present. To overcome these challenges, we developed "Fastcount," an in-house MATLAB-based algorithm for precise, automated quantification and phenotypic characterization of CTCs and CTCCs, in both 2D and 3D. Fastcount is 120 times faster than manual counting and produces reliable results with a ±7.3% deviation compared to a trained laboratory technician. By analyzing 400 GB of fluorescence imaging data, we showed that Fastcount outperforms manual counting and commercial software when cells are aggregated in 3D or staining artifacts are present, delivering more accurate results. We further employed Fastcount for automated analysis of 3D image stacks obtained from CTCCs isolated from colorectal adenocarcinoma and renal cell carcinoma blood samples. Interestingly, we observed a highly heterogeneous spatial cellular composition within CTCCs, even among clusters from the same patient. Overall, Fastcount can be employed for various applications with lab-chip devices, such as CTC detection, CTCC analysis in 3D and cell detection in biosensors.

Mapping the Potential of Microfluidics in Early Diagnosis and Personalized Treatment of Head and Neck Cancers

Head and neck cancers (HNCs) account for ~4% of all cancers in North America and encompass cancers affecting the oral cavity, pharynx, larynx, sinuses, nasal cavity, and salivary glands. The anatomical complexity of the head and neck region, characterized by highly perfused and innervated structures, presents challenges in the early diagnosis and treatment of these cancers. The utilization of sub-microliter volumes and the unique phenomenon associated with microscale fluid dynamics have facilitated the development of microfluidic platforms for studying complex biological systems. The advent of on-chip microfluidics has significantly impacted the diagnosis and treatment strategies of HNC. Sensor-based microfluidics and point-of-care devices have improved the detection and monitoring of cancer biomarkers using biological specimens like saliva, urine, blood, and serum. Additionally, tumor-on-a-chip platforms have allowed the creation of patient-specific cancer models on a chip, enabling the development of personalized treatments through high-throughput screening of drugs. In this review, we first focus on how microfluidics enable the development of an enhanced, functional drug screening process for targeted treatment in HNCs. We then discuss current advances in microfluidic platforms for biomarker sensing and early detection, followed by on-chip modeling of HNC to evaluate treatment response. Finally, we address the practical challenges that hinder the clinical translation of these microfluidic advances.

A correlation of conductivity medium and bioparticle viability on dielectrophoresis-based biomedical applications

Dielectrophoresis (DEP) bioparticle research has progressed from micro to nano levels. It has proven to be a promising and powerful cell manipulation method with an accurate, quick, inexpensive, and label-free technique for therapeutic purposes. DEP, an electrokinetic phenomenon, induces particle movement as a result of polarization effects in a nonuniform electrical field. This review focuses on current research in the biomedical field that demonstrates a practical approach to DEP in terms of cell separation, trapping, discrimination, and enrichment under the influence of the conductive medium in correlation with bioparticle viability. The current review aims to provide readers with an in-depth knowledge of the fundamental theory and principles of the DEP technique, which is influenced by conductive medium and to identify and demonstrate the biomedical application areas. The high conductivity of physiological fluids presents obstacles and opportunities, followed by bioparticle viability in an electric field elaborated in detail. Finally, the drawbacks of DEP-based systems and the outlook for the future are addressed. This article will aid in advancing technology by bridging the gap between bioscience and engineering. We hope the insights presented in this review will improve cell suspension medium and promote DEP-viable bioparticle manipulation for health-care diagnostics and therapeutics.

Application of Microfluidics in Detection of Circulating Tumor Cells

Tumor metastasis is one of the main causes of cancer incidence and death worldwide. In the process of tumor metastasis, the isolation and analysis of circulating tumor cells (CTCs) plays a crucial role in the early diagnosis and prognosis of cancer patients. Due to the rarity and inherent heterogeneity of CTCs, there is an urgent need for reliable CTCs separation and detection methods in order to obtain valuable information on tumor metastasis and progression from CTCs. Microfluidic technology is increasingly used in various studies of CTCs separation, identification and characterization because of its unique advantages, such as low cost, simple operation, less reagent consumption, miniaturization of the system, rapid detection and accurate control. This paper reviews the research progress of microfluidic technology in CTCs separation and detection in recent years, as well as the potential clinical application of CTCs, looks forward to the application prospect of microfluidic technology in the treatment of tumor metastasis, and briefly discusses the development prospect of microfluidic biosensor.

Hybrid/Atypical Forms of Circulating Tumor Cells: Current State of the Art

Cancer is one of the most common diseases worldwide, and its treatment is associated with many challenges such as drug and radioresistance and formation of metastases. These difficulties are due to tumor heterogeneity, which has many causes. One may be the cell fusion, a process that is relevant to both physiological (e.g., wound healing) and pathophysiological (cancer and viral infection) processes. This literature review aimed to summarize the existing data on the hybrid/atypical forms of circulating cancer cells and their role in tumor progression. For that, the bioinformatics search in universal databases, such as PubMed, NCBI, and Google Scholar was conducted by using the keywords “hybrid cancer cells”, “cancer cell fusion”, etc. In this review the latest information related to the hybrid tumor cells, theories of their genesis, characteristics of different variants with data from our own researches are presented. Many aspects of the hybrid cell research are still in their infancy. However, with the level of knowledge already accumulated, circulating hybrids such as CAML and CHC could be considered as promising biomarkers of cancerous tumors, and even more as a new approach to cancer treatment.

Basic Principles and Recent Advances in Magnetic Cell Separation

Magnetic cell separation has become a key methodology for the isolation of target cell populations from biological suspensions, covering a wide spectrum of applications from diagnosis and therapy in biomedicine to environmental applications or fundamental research in biology. There now exists a great variety of commercially available separation instruments and reagents, which has permitted rapid dissemination of the technology. However, there is still an increasing demand for new tools and protocols which provide improved selectivity, yield and sensitivity of the separation process while reducing cost and providing a faster response. This review aims to introduce basic principles of magnetic cell separation for the neophyte, while giving an overview of recent research in the field, from the development of new cell labeling strategies to the design of integrated microfluidic cell sorters and of point-of-care platforms combining cell selection, capture, and downstream detection. Finally, we focus on clinical, industrial and environmental applications where magnetic cell separation strategies are amongst the most promising techniques to address the challenges of isolating rare cells.