An Electroactive Biotin-Doped Polypyrrole Substrate That Immobilizes and Releases EpCAM-Positive Cancer Cells

Competitive electrochemical sensing for cancer cell evaluation based on thionine-interlinked signal probes

The development of effective methods for tracking cancer cells is of significant importance in the early diagnosis and treatment of tumor diseases. Compared with the developed techniques, the electrochemical assay has shown considerable potential for monitoring glycan expression on the cell surface using nondestructive means. However, the application expansion of the electrochemical strategy is strongly impeded owing to its dependence on electroactive species. In this study, a competitive electrochemical strategy was reported for monitoring cancer cells based on mannose (a typical glycan) as a clinical biomarker. Herein, functionalized carbon nanotubes were used to load the thiomannosyl dimer, and thionine-interlinking signal probes were designed for competitive recognition. After effective competition between cancer cells and the anchored mannose, a decreased current was obtained as the cell concentration increased. Under optimal conditions, the proposed biosensor exhibited attractive performance for cancer cell analysis with a detection limit as low as 20 cells per mL for QGY-7701 and 35 cells per mL for QGY-7703, facilitating great promise for the sensitive detection of cancer cells and thus showing potential applications in cancer diagnosis.

Recapitulating dynamic ECM ligand presentation at biomaterial interfaces: Molecular strategies and biomedical prospects

The extracellular matrix (ECM) provides not only physical support for the tissue structural integrity, but also dynamic biochemical cues capable of regulating diverse cell behaviors and functions. Biomaterial surfaces with dynamic ligand presentation are capable of mimicking the dynamic biochemical cues of ECM, showing ECM-like functions to modulate cell behaviors. This review paper described an overview of present dynamic biomaterial interfaces by focusing on currently developed molecular strategies for dynamic ligand presentation. The paradigmatic examples for each strategy were separately discussed. In addition, the regulation of some typical cell behaviors on these dynamic biointerfaces including cell adhesion, macrophage polarization, and stem cell differentiation, and their potential applications in pathogenic cell isolation, single cell analysis, and tissue engineering are highlighted. We hope it would not only clarify a clear background of this field, but also inspire to exploit novel molecular strategies and more applications to match the increasing demand of manipulating complex cellular processes in biomedicine.

Well-Defined Nanostructured Biointerfaces: Strengthened Cellular Interaction for Circulating Tumor Cells Isolation

The topographic features at the cell-material biointerface are critical for cellular sensing of the extracellular environment (ECM) and have gradually been recognized as key factors that regulate cell adhesion behavior. Herein, a well-defined nanostructured biointerface is fabricated via a new generation of mussel-inspired polymer coating to mimic the native ECM structures. Upon the bioinert background presence and biospecific ligands conjugation, the affinity of cancer cells to the resulting biofunctional surfaces, which integrate topographic features and biochemical cues, is greatly strengthened. Both the conjugated bioligand density, filopodia formation, and focal adhesion expression are significantly enhanced by the surficial nano-features with an optimized size-scale. Thus, this nanostructured biointerface exhibits high capture efficiency for circulating tumor cells (CTCs) with high sensitivity, high biospecificity, and high purity. Benefiting from the unique bioligands conjugation chemistry herein, the captured cancer cells can be responsively detached from the biointerfaces without damage for downstream analysis. The present biofunctional nanostructured interfaces offer a good solution to address current challenges to efficiently isolate rare CTCs from blood samples for earlier cancer diagnosis.

Pipette-like action of a reusable and NIR light-responsive film for the aspiration and removal of viable cancer cells

A reusable and NIR light-responsive composite membrane is developed to capture/release viable cancer cells.

Photo-Irresponsive Molecule-Amplified Cell Release on Photoresponsive Nanostructured Surfaces

Cell manipulation has raised extensive concern owing to its underlying applications in numerous biological situations such as cell-matrix interaction, tissue engineering, and cell-based diagnosis. Generally, light is considered as a superior candidate for manipulating cells (e.g., cell release) due to their high spatiotemporal precision and non-invasion. However, it remains a big challenge to release cells with high efficiency due to their potential limitation of the light-triggered wettability transition on photoresponsive surfaces. In this study, we report a photoresponsive spiropyran-coated nanostructured surface that enables highly efficient release of cancer cells, amplified by the introduction of a photo-irresponsive molecule. On one hand, structural recognition stems from topological interaction between nanofractal surfaces and the protrusions of cancer cells. On the other, molecular recognition can be amplified by a photo-irresponsive and hydrophilic molecule by reducing the steric hindrance of photoresponsive components and resisting nonspecific cell adhesion. Therefore, this study may afford a novel avenue for developing advanced smart materials for high-quality biological analysis and clinical diagnosis.

Direct isolation and characterization of circulating exosomes from biological samples using magnetic nanowires

BACKGROUND

Tumor-derived exosomes are gaining attention as important factors that facilitate communication between neighboring cells and manipulate cellular processes associated with cancer development or progression. The conventional techniques for the isolation and detection of exosomes face several limitations, restricting their clinical applications. Hence, a highly efficient technique for the isolation and identification of exosomes from biological samples may provide critical information about exosomes as biomarkers and improve our understanding of their unique role in cancer research. Here, we describe the use of antibody cocktail-conjugated magnetic nanowires to isolate exosomes from plasma of breast and lung cancer patients.

METHODS

The isolated exosomes were characterized based on size and concentration using nanoparticle tracking analysis. Levels of exosomal proteins were measured by bicinchoninic acid assay and enzyme-linked immunosorbent assay. Morphology was visualized by transmission electron microscopy. Immunoblotting (Western blotting) was used to detect the presence of exosomal markers.

RESULTS

The use of antibody cocktail-conjugated magnetic nanowires resulted in approximately threefold greater yield when compared to the conventional methods. The elongated feature of nanowires significantly improved the efficiency of exosome isolation, suggesting its potential to be translated in diverse clinical applications, including cancer diagnosis and treatment.

CONCLUSIONS

The nanowire-based method allows rapid isolation of homogeneous population of exosomes with relatively high yield and purity from even small amounts of sample. These results suggest that this method has the potential for clinical applications requiring highly purified exosomes for the analysis of protein, lipid, mRNA, and miRNA.

Synthesis of a multi-functional DNA nanosphere barcode system for direct cell detection

Nucleic acid-based technologies have been applied to numerous biomedical applications. As a novel material for target detection, DNA has been used to construct a barcode system with a range of structures. This paper reports multi-functionalized DNA nanospheres (DNANSs) by rolling circle amplification (RCA) with several functionalized nucleotides. DNANSs with a barcode system were designed to exhibit fluorescence for coding enhanced signals and contain biotin for more functionalities, including targeting through the biotin-streptavidin (biotin-STA) interaction. Functionalized deoxynucleotide triphosphates (dNTPs) were mixed in the RCA process and functional moieties can be expressed on the DNANSs. The anti-epidermal growth factor receptor antibodies (anti-EGFR Abs) can be conjugated on DNANSs for targeting cancer cells specifically. As a proof of concept, the potential of the multi-functional DNANS barcode was demonstrated by direct cell detection as a simple detection method. The DNANS barcode provides a new route for the simple and rapid selective recognition of cancer cells.

Tumor cell capture patterns around aptamer-immobilized microposts in microfluidic devices

Circulating tumor cells (CTCs) have shown potential for cancer diagnosis and prognosis. Affinity-based CTC isolation methods have been proved to be efficient for CTC detection in clinical blood samples. One of the popular choices for affinity-based CTC isolation is to immobilize capture agents onto an array of microposts in microchannels, providing high CTC capture efficiency due to enhanced interactions between tumor cells and capture agents on the microposts. However, how the cells interact with microposts under different flow conditions and what kind of capture pattern results from the interactions have not been fully investigated; a full understanding of these interactions will help to design devices and choose experimental conditions for higher CTC capture effeciency. We report our study on their interaction and cell distribution patterns around microposts under different flow conditions. Human acute lymphoblastic leukemia cells (CCRF-CEM) were used as target cancer cells in this study, while the Sgc8 aptamer that has specific binding with CCRF-CEM cells was employed as a capture agent. We investigated the effects of flow rates and micropost shapes on the cell capture efficiency and capture patterns on microposts. While a higher flow rate decreased cell capture efficiency, we found that the capture pattern around microposts also changed, with much more cells captured in the front half of a micropost than at the back half. We also found the ratio of cells captured on microposts to the cells captured by both microposts and channel walls increased as a function of the flow rate. We compared circular microposts with an elliptical shape and found that the geometry affected the capture distribution around microposts. In addition, we have developed a theoretical model to simulate the interactions between tumor cells and micropost surfaces, and the simulation results are in agreement with our experimental observation.

Degradable Zinc-Phosphate-Based Hierarchical Nanosubstrates for Capture and Release of Circulating Tumor Cells

Circulating tumor cells (CTCs) play a significant role in cancer diagnosis and personalized therapy, and it is still a significant challenge to efficiently capture and gently release CTCs from clinical samples for downstream manipulation and molecular analysis. Many CTC devices incorporating various nanostructures have been developed for CTC isolation with sufficient capture efficiency, however, fabricating such nanostructured substrates often requires elaborate design and complicated procedures. Here we fabricate a degradable zinc-phosphate-based hierarchical nanosubstrate (HZnPNS), and we demonstrate its excellent CTC-capture performance along with effective cell-release capability for downstream molecular analysis. This transparent hierarchical architecture prepared by a low-temperature hydrothermal method, enables substantially enhanced capture efficiency and convenient imaging. Biocompatible sodium citrate could rapidly dissolve the architecture at room temperature, allowing that 88 ± 4% of captured cells are gently released with a high viability of 92 ± 1%. Furthermore, antiepithelial cell adhesion molecule antibody functionalized HZnPNS (anti-EpCAM/HZnPNS) was successfully applied to isolate CTCs from whole blood samples of cancer patients, as well as release CTCs for global DNA methylation analysis, indicating it will serve as a simple and reliable alternative platform for CTC detection.

Graphene Oxide Nanosheets Modified with Single-Domain Antibodies for Rapid and Efficient Capture of Cells

Peripheral blood can provide valuable information on an individual's immune status. Cell-based assays typically target leukocytes and their products. Characterization of leukocytes from whole blood requires their separation from the far more numerous red blood cells.1 Current methods to classify leukocytes, such as recovery on antibody-coated beads or fluorescence-activated cell sorting require long sample preparation times and relatively large sample volumes.2 A simple method that enables the characterization of cells from a small peripheral whole blood sample could overcome limitations of current analytical techniques. We describe the development of a simple graphene oxide surface coated with single-domain antibody fragments. This format allows quick and efficient capture of distinct WBC subpopulations from small samples (∼30 μL) of whole blood in a geometry that does not require any specialized equipment such as cell sorters or microfluidic devices.

A Self-Cleaning TiO2 Nanosisal-like Coating toward Disposing Nanobiochips of Cancer Detection

The advanced nanobiochips have been widely employed in diagnosing some high incidence of diseases because of their portable, low-cost, and highly sensitive features. However, the subsequent disposal of these wastes remains unexposed, probably giving rise to serious environmental pollution and health risks similar to traditional biomedical waste. Here, we have presented a TiO2 nanosisal-like coating for disposing nanobiochip waste via the photoresponsive self-cleaning features of the nanobiochip, demonstrated by the nanochips of cancer detection. Moreover, the high specificity and sensitivity of nanochips can be maintained by integrating unique nanostructured coatings (i.e., nanosisal-like coating) with specific recognition molecules (i.e., anti-EpCAM). Therefore, this study will provide a promising strategy for the design and management of practical nanobiodevices, thereby eliminating the old path "pollute first, clean up later".

Capturing Cancer: Emerging Microfluidic Technologies for the Capture and Characterization of Circulating Tumor Cells

Circulating tumor cells (CTCs) escape from primary or metastatic lesions and enter into circulation, carrying significant information of cancer progression and metastasis. Capture of CTCs from the bloodstream and the characterization of these cells hold great significance for the detection, characterization, and monitoring of cancer. Despite the urgent need from clinics, it remains a major challenge to capture and retain these rare cells from human blood with high specificity and yield. Recent exciting advances in micro/nanotechnology, microfluidics, and materials science have enable versatile, robust, and efficient cell isolation and processing through the development of new micro/nanoengineered devices and biomaterials. This review provides a summary of recent progress along this direction, with a focus on emerging methods for CTC capture and processing, and their application in cancer research. Furthermore, classical as well as emerging cellular characterization methods are reviewed to reveal the role of CTCs in cancer progression and metastasis, and hypotheses are proposed in regard to the potential emerging research directions most desired in CTC-related cancer research.

Biotin-triggered decomposable immunomagnetic beads for capture and release of circulating tumor cells

Isolation of rare, pure, and viable circulating tumor cells (CTCs) provides a significant insight in early cancer diagnosis, and release of captured CTCs without damage for ex vivo culture may offer an opportunity for personalized cancer therapy. In this work, we described a biotin-triggered decomposable immunomagnetic system, in which peptide-tagged antibody designed by chemical conjugation was specifically immobilized on engineered protein-coated magnetic beads. The interaction between peptide and engineered protein can be reversibly destroyed by biotin treatment, making capture and release of CTCs possible. Furthermore, the peptide could mediate multiple antibodies' coimmobilization on engineered protein-coated magnetic beads, by which capture efficiency for CTCs was obviously improved. Quantitative results showed that 70% of captured cells could be released by biotin addition, and 85% of released cells remained viable. In addition, 79% of cancer cells spiked in human whole blood were captured and could also be successfully released for culture. Finally, immunomagnetic beads simultaneously loaded with anti-EpCAM, anti-HER2, and anti-EGFR were successfully applied to isolate and detect CTCs in 17 cancer patients' peripheral blood samples, and 2-215 CTCs were identified with high purity. These results suggest that our method is reliable and has great potential in CTC detection for CTC-based molecular profiling, diagnosis, and therapy.

Nanotopographic Biomaterials for Isolation of Circulating Tumor Cells

Circulating tumor cells (CTCs) shed from the primary tumor mass and circulating in the bloodstream of patients are believed to be vital to understand of cancer metastasis and progression. Capture and release of CTCs for further enumeration and molecular characterization holds the key for early cancer diagnosis, prognosis and therapy evaluation. However, detection of CTCs is challenging due to their rarity, heterogeneity and the increasing demand of viable CTCs for downstream biological analysis. Nanotopographic biomaterial-based microfluidic systems are emerging as promising tools for CTC capture with improved capture efficiency, purity, throughput and retrieval of viable CTCs. This review offers a brief overview of the recent advances in this field, including CTC detection technologies based on nanotopographic biomaterials and relevant nanofabrication methods. Additionally, the possible intracellular mechanisms of the intrinsic nanotopography sensitive responses that lead to the enhanced CTC capture are explored.