Rapid and efficient isolation and detection of circulating tumor cells based on ZnS:Mn2+ quantum dots and magnetic nanocomposites

Optical nanomaterial-based detection of biomarkers in liquid biopsy

Liquid biopsy, which is a minimally invasive procedure as an alternative to tissue biopsy, has been introduced as a new diagnostic/prognostic measure. By screening disease-related markers from the blood or other biofluids, it promises early diagnosis, timely prognostication, and effective treatment of the diseases. However, there will be a long way until its realization due to its conceptual and practical challenges. The biomarkers detected by liquid biopsy, such as circulating tumor cell (CTC) and circulating tumor DNA (ctDNA), are extraordinarily rare and often obscured by an abundance of normal cellular components, necessitating ultra-sensitive and accurate detection methods for the advancement of liquid biopsy techniques. Optical biosensors based on nanomaterials open an important opportunity in liquid biopsy because of their enhanced sensing performance with simple and practical properties. In this review article, we summarized recent innovations in optical nanomaterials to demonstrate the sensitive detection of protein, peptide, ctDNA, miRNA, exosome, and CTCs. Each study prepares the optical nanomaterials with a tailored design to enhance the sensing performance and to meet the requirements of each biomarker. The unique optical characteristics of metallic nanoparticles (NPs), quantum dots, upconversion NPs, silica NPs, polymeric NPs, and carbon nanomaterials are exploited for sensitive detection mechanisms. These recent advances in liquid biopsy using optical nanomaterials give us an opportunity to overcome challenging issues and provide a resource for understanding the unknown characteristics of the biomarkers as well as the mechanism of the disease.

Recent Update Roles of Magnetic Nanoparticles in Circulating Tumor Cell (CTC)/Non-CTC Separation

Metastasis of cancer is a major cause of death worldwide. Circulating tumor cells (CTCs) are important in the metastatic process of cancer. CTCs are able to circulate in the bloodstream. Therefore, they can be used as biomarkers of metastasis. However, CTCs are rare when compared to a large number of blood cells in the blood. Many CTC detection methods have been developed to increase CTC detection efficiency. Magnetic nanoparticles (MNPs) have attracted immense attention owing to their potential medical applications. They are particularly appealing as a tool for cell separation. Because of their unique properties, MNPs are of considerable interest for the enrichment of CTCs through CTC or non-CTC separation. Herein, we review recent developments in the application of MNPs to separate CTCs or non-CTCs in samples containing CTCs. This review provides information on new approaches that can be used to detect CTCs in blood samples. The combination of MNPs with other particles for magnetic-based cell separation for CTC detection is discussed. Furthermore, different approaches for synthesizing MNPs are included in this review.

Current research status of tumor cell biomarker detection

With the annual increases in the morbidity and mortality rates of tumors, the use of biomarkers for early diagnosis and real-time monitoring of tumor cells is of great importance. Biomarkers used for tumor cell detection in body fluids include circulating tumor cells, nucleic acids, protein markers, and extracellular vesicles. Among them, circulating tumor cells, circulating tumor DNA, and exosomes have high potential for the prediction, diagnosis, and prognosis of tumor diseases due to the large amount of valuable information on tumor characteristics and evolution; in addition, in situ monitoring of telomerase and miRNA in living cells has been the topic of extensive research to understand tumor development in real time. Various techniques, such as enzyme-linked immunosorbent assays, immunoblotting, and mass spectrometry, have been widely used for the detection of these markers. Among them, the detection of tumor cell markers in body fluids based on electrochemical biosensors and fluorescence signal analysis is highly preferred because of its high sensitivity, rapid detection and portable operation. Herein, we summarize recent research progress in the detection of tumor cell biomarkers in body fluids using electrochemical and fluorescence biosensors, outline the current research status of in situ fluorescence monitoring and the analysis of tumor markers in living cells, and discuss the technical challenges for their practical clinical application to provide a reference for the development of new tumor marker detection methods.

Hybrid nanoarchitectonics of molybdenum dioxide (MoO2) and doxorubicin (DOX) for synergistic chemo-photothermal-based breast carcinoma therapy

Cancer has emerged as one of the severe ailments due to the uncontrolled proliferation rate of cells, accounting for millions of deaths annually. Despite the availability of various treatment strategies, including surgical interventions, radiation, and chemotherapy, tremendous advancements in the past two decades of research have evidenced the generation of different nanotherapeutic designs toward providing synergistic therapy. In this study, we demonstrate the assembly of a versatile nanoplatform based on the hyaluronic acid (HA)-coated molybdenum dioxide (MoO₂) assemblies to act against breast carcinoma. The hydrothermal approach-assisted MoO₂ constructs are immobilized with doxorubicin (DOX) molecules on the surface. Further, these MoO₂-DOX hybrids are encapsulated with the HA polymeric framework. Furthermore, the versatile nanocomposites of HA-coated MoO₂-DOX hybrids are systematically characterized using various characterization techniques, and explored biocompatibility in the mouse fibroblasts (L929 cell line), as well as synergistic photothermal (808-nm laser irradiation for 10 min, 1 W/cm²) and chemotherapeutic properties against breast carcinoma (4T1 cells). Finally, the mechanistic views concerning the apoptosis rate are explored using the JC-1 assay to measure the intracellular mitochondrial membrane potential (MMP) levels. In conclusion, these findings indicated excellent photothermal and chemotherapeutic efficacies, exploring the enormous potential of MoO₂ composites against breast cancer.

Current and Emerging Techniques for Diagnosis and MRD Detection in AML: A Comprehensive Narrative Review

Acute myeloid leukemia (AML) comprises a group of hematologic neoplasms characterized by abnormal differentiation and proliferation of myeloid progenitor cells. AML is associated with poor outcome due to the lack of efficient therapies and early diagnostic tools. The current gold standard diagnostic tools are based on bone marrow biopsy. These biopsies, apart from being very invasive, painful, and costly, have low sensitivity. Despite the progress uncovering the molecular pathogenesis of AML, the development of novel detection strategies is still poorly explored. This is particularly important for patients that check the criteria for complete remission after treatment, since they can relapse through the persistence of some leukemic stem cells. This condition, recently named as measurable residual disease (MRD), has severe consequences for disease progression. Hence, an early and accurate diagnosis of MRD would allow an appropriate therapy to be tailored, improving a patient's prognosis. Many novel techniques with high potential in disease prevention and early detection are being explored. Among them, microfluidics has flourished in recent years due to its ability at processing complex samples as well as its demonstrated capacity to isolate rare cells from biological fluids. In parallel, surface-enhanced Raman scattering (SERS) spectroscopy has shown outstanding sensitivity and capability for multiplex quantitative detection of disease biomarkers. Together, these technologies can allow early and cost-effective disease detection as well as contribute to monitoring the efficiency of treatments. In this review, we aim to provide a comprehensive overview of AML disease, the conventional techniques currently used for its diagnosis, classification (recently updated in September 2022), and treatment selection, and we also aim to present how novel technologies can be applied to improve the detection and monitoring of MRD.

Nanomaterial-Based Immunocapture Platforms for the Recognition, Isolation, and Detection of Circulating Tumor Cells

Circulating tumor cells (CTCs) are a type of cancer cells that circulate in the peripheral blood after breaking away from solid tumors and are essential for the establishment of distant metastasis. Up to 90% of cancer-related deaths are caused by metastatic cancer. As a new type of liquid biopsy, detecting and analyzing CTCs will provide insightful information for cancer diagnosis, especially the in-time disease status, which would avoid some flaws and limitations of invasive tissue biopsy. However, due to the extremely low levels of CTCs among a large number of hematologic cells, choosing immunocapture platforms for CTC detection and isolation will achieve good performance with high purity, selectivity, and viability. These properties are directly associated with precise downstream analysis of CTC profiling. Recently, inspired by the nanoscale interactions of cells in the tissue microenvironment, platforms based on nanomaterials have been widely explored to efficiently enrich and sensitively detect CTCs. In this review, various immunocapture platforms based on different nanomaterials for efficient isolation and sensitive detection of CTCs are outlined and discussed. First, the design principles of immunoaffinity nanomaterials are introduced in detail. Second, the immunocapture and release of platforms based on nanomaterials ranging from nanoparticles, nanostructured substrates, and immunoaffinity microfluidic chips are summarized. Third, recent advances in single-cell release and analysis of CTCs are introduced. Finally, some perspectives and challenges are provided in future trends of CTC studies.

Near-Infrared-II Quantum Dots for In Vivo Imaging and Cancer Therapy

In vivo fluorescence imaging can perform real-time, noninvasive, and high spatiotemporal resolution imaging to accurately obtain the dynamic biological information in vivo, which plays significant roles in the early diagnosis and treatment of cancer. However, traditional in vivo fluorescence imaging usually operates in the visible and near-infrared (NIR)-I windows, which are severely interfered by the strong tissue absorption, tissue scattering, and autofluorescence. The emergence of NIR-II imaging at 1000-1700 nm significantly breaks through the imaging limitations in deep tissues, due to less tissue scattering and absorption. Benefiting from the outstanding optical properties of NIR-II quantum dots (QDs), such as high brightness and good photostability, in vivo fluorescence imaging exhibits excellent temporal-spatial resolution and large penetration depth, and QDs have become a kind of promising fluorescent biomarkers in the field of in vivo fluorescence imaging. Herein, the authors review NIR-II QDs from preparation to modification, and summarize recent applications of NIR-II QDs, including in vivo imaging and imaging-guided therapies. Finally, they discuss the special concerns when NIR-II QDs are shifted from in vivo imaging applications to further in-depth applications.

Circulating tumor cells: biology and clinical significance

Circulating tumor cells (CTCs) are tumor cells that have sloughed off the primary tumor and extravasate into and circulate in the blood. Understanding of the metastatic cascade of CTCs has tremendous potential for the identification of targets against cancer metastasis. Detecting these very rare CTCs among the massive blood cells is challenging. However, emerging technologies for CTCs detection have profoundly contributed to deepening investigation into the biology of CTCs and have facilitated their clinical application. Current technologies for the detection of CTCs are summarized herein, together with their advantages and disadvantages. The detection of CTCs is usually dependent on molecular markers, with the epithelial cell adhesion molecule being the most widely used, although molecular markers vary between different types of cancer. Properties associated with epithelial-to-mesenchymal transition and stemness have been identified in CTCs, indicating their increased metastatic capacity. Only a small proportion of CTCs can survive and eventually initiate metastases, suggesting that an interaction and modulation between CTCs and the hostile blood microenvironment is essential for CTC metastasis. Single-cell sequencing of CTCs has been extensively investigated, and has enabled researchers to reveal the genome and transcriptome of CTCs. Herein, we also review the clinical applications of CTCs, especially for monitoring response to cancer treatment and in evaluating prognosis. Hence, CTCs have and will continue to contribute to providing significant insights into metastatic processes and will open new avenues for useful clinical applications.

Detection and clinical significance of circulating tumor cells in colorectal cancer

Histopathological examination (biopsy) is the "gold standard" for the diagnosis of colorectal cancer (CRC). However, biopsy is an invasive method, and due to the temporal and spatial heterogeneity of the tumor, a single biopsy cannot reveal the comprehensive biological characteristics and dynamic changes of the tumor. Therefore, there is a need for new biomarkers to improve CRC diagnosis and to monitor and treat CRC patients. Numerous studies have shown that "liquid biopsy" is a promising minimally invasive method for early CRC detection. A liquid biopsy mainly samples circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), microRNA (miRNA) and extracellular vesicles (EVs). CTCs are malignant cells that are shed from the primary tumors and/or metastases into the peripheral circulation. CTCs carry information on both primary tumors and metastases that can reflect dynamic changes in tumors in a timely manner. As a promising biomarker, CTCs can be used for early disease detection, treatment response and disease progression evaluation, disease mechanism elucidation, and therapeutic target identification for drug development. This review will discuss currently available technologies for plasma CTC isolation and detection, their utility in the management of CRC patients and future research directions.

Recent Development of Nanomaterials-Based Cytosensors for the Detection of Circulating Tumor Cells

The accurate analysis of circulating tumor cells (CTCs) holds great promise in early diagnosis and prognosis of cancers. However, the extremely low abundance of CTCs in peripheral blood samples limits the practical utility of the traditional methods for CTCs detection. Thus, novel and powerful strategies have been proposed for sensitive detection of CTCs. In particular, nanomaterials with exceptional physical and chemical properties have been used to fabricate cytosensors for amplifying the signal and enhancing the sensitivity. In this review, we summarize the recent development of nanomaterials-based optical and electrochemical analytical techniques for CTCs detection, including fluorescence, colorimetry, surface-enhanced Raman scattering, chemiluminescence, electrochemistry, electrochemiluminescence, photoelectrochemistry and so on.

Immunomagnetic separation of circulating tumor cells with microfluidic chips and their clinical applications

Circulating tumor cells (CTCs) are tumor cells detached from the original lesion and getting into the blood and lymphatic circulation systems. They potentially establish new tumors in remote areas, namely, metastasis. Isolation of CTCs and following biological molecular analysis facilitate investigating cancer and coming out treatment. Since CTCs carry important information on the primary tumor, they are vital in exploring the mechanism of cancer, metastasis, and diagnosis. However, CTCs are very difficult to separate due to their extreme heterogeneity and rarity in blood. Recently, advanced technologies, such as nanosurfaces, quantum dots, and Raman spectroscopy, have been integrated with microfluidic chips. These achievements enable the next generation isolation technologies and subsequent biological analysis of CTCs. In this review, we summarize CTCs' separation with microfluidic chips based on the principle of immunomagnetic isolation of CTCs. Fundamental insights, clinical applications, and potential future directions are discussed.

ZnO nanowire-integrated bio-microchips for specific capture and non-destructive release of circulating tumor cells

Circulating tumor cells (CTCs) are one type of significant biomarker in cancer patients' blood that have been attracting attention from researchers for decades, and their efficient and viable isolation is of vital importance in cancer prevention and treatment. However, the development of efficient and low-cost bio-microchips still faces significant challenges. In this paper, we construct a novel three-dimensional micro-nano bio-microchip that has dual functions of specifically capturing and non-destructively releasing cancer cells. ZnO nanowire arrays were vertically grown on the surface of a polydimethylsiloxane (PDMS) pillar substrate with a gear structure (ZnO-coated G-PDMS pillar microchips). The gear structure provides more binding sites for antibodies and target cancer cells, while ZnO nanowires provide a rough surface for CTC attachment and size-specific effects for retaining CTCs. For subsequent culture and bioanalysis, the captured CTCs can be non-destructively released with high efficiency and good viability using a mild acidic solution treatment. Furthermore, the manufacturing process of the G-PDMS pillar microchips is convenient and low-cost, and the preparation approach of the ZnO nanowire is mature and simple to operate. In particular, the bio-microchips showed high capture efficiency (91.11% ± 5.53%) and excellent cell viability (96%) using a spiked cell sample. Moreover, we successfully achieved the specific fluorescent labeling of CTCs in 9 clinical breast cancer patients' samples. The ZnO-coated G-PDMS pillar microchips not only have great potential for new target drug development for cancer stem cells but also open up new opportunities for individualized treatment.

Antibody-Functional Microsphere-Integrated Filter Chip with Inertial Microflow for Size-Immune-Capturing and Digital Detection of Circulating Tumor Cells

Circulating tumor cells (CTCs) in blood is the direct cause of tumor metastasis. The isolation and detection of CTCs in the whole blood is very important and of clinical value in early diagnosis, postoperative review, and personalized treatment. It is difficult to separate all types of CTCs that efficiently rely on a single path due to cancer cell heterogenicity. Here, we designed a new kind of "filter chip" for the retention of CTCs with very high efficiency by integrating the effects of cell size and specific antigens on the surface of tumor cells. The filter chip consists of a semicircle arc and arrays and can separate large-scale CTC microspheres, which combined with CTCs automatically. We synthesized interfacial zinc oxide coating with nanostructure on the surface of the microsphere to increase the specific surface area to enhance the capturing efficiency of CTCs. Microspheres, trapped in the arrays, would entrap CTCs, too. The combination of the three kinds of strategies resulted in more than 90% capture efficiency of different tumor cell lines. Furthermore, it is easy to find and isolate the circulating tumor cells from the chip as tumor cells would be fixed inside the structure of a filter chip. To avoid the high background contamination when a few CTCs are surrounded by millions of nontarget cells, a digital detection method was applied to improve the detection sensitivity. The CTCs in the whole blood were specifically labeled by the antibody-DNA conjugates and detected via the DNA of the conjugates with a signal amplification. The strategy of the antibody-functional microsphere-integrated microchip for cell sorting and detection of CTCs may find broad implications that favor the fundamental cancer biology research, the precise diagnosis, and monitoring of cancer in the clinics.