Detection Of MCF-7 Cells Research Articles

Organic photoelectrochemical transistor biosensor based on BiVO4-ZnIn2S4 material for efficient and sensitive detection of MCF-7 cells

Recently, organic photoelectrochemical transistor (OPECT) has become a very interesting biological measurement method in photoelectrochemical (PEC) bioanalysis and future bio-related applications. OPECT is expected to be a powerful tool for disease detection and early warning. Circulating tumor cells (CTCs) are generally deemed to be the dominant factor of tumor metastasis, and 90 % of cancer patients die from this metastatic disease. Therefore, there is an imminent need to develop a highly sensitive CTCs detection sensing system to improve the survival rate of cancer patients. Here, we use a DNA tetrahedrons (DNA NTH) with an aptamer at the top to immobilize on the surface of the photoelectric material to capture cells (MCF-7). Specifically, the BiVO4-ZnIn2S4 hybrid was synthesized by a simple hydrothermal method, which can effectively modulated devices with high current gain. Au NPs were directly integrated on the electrode surface to construct an OPECT photoelectric sensing platform. Subsequently, the aptamer which is thiol-functionalized (SH-Apt) was immobilized on the electrode surface. Because of the overexpression of MUC1 protein on the cell membrane, it can specifically capture MCF-7 cells. The introduction of MCF-7 cells resulted in a significant decrease in the current signal. There is a relationship between the change of photocurrent and the logarithm of MCF-7 cell concentration, which is a good linear relationship ranging from 50 to 5 × 105 cell mL−1. The obtained detection limit is 43 cell mL−1. The biosensor has high selectivity and sensitivity, and achieves sensitive detection of MCF-7.

Functionalizing of magnetic nanoparticles as nano-architecture towards bioimaging and colorimetric recognition of MCF-7 cells: dual opto-sensing and fluorescence monitoring for early-stage diagnosis of breast cancer.

Considering the high incidence of breast cancer, a sensitive and specific approach is crucial for its early diagnosis and follow-up treatment. Folate receptors (FR), which are highly expressed on the epithelial tissue such as breast cancer cells (e.g., MCF-7), have been used in cancer diagnosis and bioimaging. This study presents an innovative colorimetric and fluorescence bioimaging platform towards MCF-7 using folic acid (FA)-conjugated iron-oxide magnetite silica-based nanocomposite (Fe3O4@SiO2-3-aminopropyl)triethoxysilane (APTES-NH2)@cysteine (Cyt)-Cyt@FA). For identification of MCF-7, the polyvinylpyrrolidone (PVP)-capped-platinum (Pt) nanoparticle was utilized as a nanozyme to catalyze the reaction between 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2 for visual detection of MCF-7 cells. Colorimetric changes are detectable by the naked eye and spectrophotometry at the wavelength of 450nm, with a linear range of 50-5000 cells/mL and a detection limit of 30 cells/mL. The Fe3O4@SiO2-APTES-NH2@Cyt-Cyt@FA complex was modified with rhodamine B as a fluorescence bioimaging probe to monitor FR-overexpressed MCF-7 cells. The nanocomposite is biocompatible with a toxicity threshold of about 800µg/mL. These methodologies facilitate bioimaging and colorimetric assays without sophisticated instrumentation, offering high specificity, sensitivity, repeatability, and stability, making them suitable as versatile methods for detecting and bioimaging cancer cells.

An Integrated Inertial-Magnetophoresis Microfluidic Chip Online-Coupled with ICP-MS for Rapid Separation and Precise Detection of Circulating Tumor Cells.

Circulating tumor cells (CTCs) are recognized as promising targets for liquid biopsy, which play an important role in early diagnosis and efficacy monitoring of cancer. However, due to the extreme scarcity of CTCs and partial size overlap between CTCs and white blood cells (WBCs), the separation and detection of CTCs from blood remain a big challenge. To address this issue, we fabricated a microfluidic chip by integrating a passive contraction-expansion array (CEA) inertial sorting zone and an active magnetophoresis zone with the trapezoidal groove and online coupled it with inductively coupled plasma mass spectrometry (ICP-MS) for rapid separation and precise detection of MCF-7 cells (as a model CTC) in blood samples. In the integrated microfluidic chip, most of the small-sized WBCs can be rapidly removed in the circular CEA inertial sorter, while the rest of the magnetically labeled WBCs can be further captured in the trapezoidal groove under the magnetic field. As a result, the rapid separation of MCF-7 cells from blood samples was achieved with an average recovery of 91.6% at a sample flow rate of 200 μL min-1. The developed online integrated inertial-magnetophoresis microfluidic chip-ICP-MS system has been applied for the detection of CTCs in real clinical blood samples with a fast analysis speed (5 min per 1 mL blood). CTCs were detected in all 24 blood samples from patients with different types of cancer, exhibiting excellent application potential in clinical diagnosis.

Multiplex Sensing of Biomarkers on the Cancer Cell Surface by an Epithelial-Mesenchymal Transition (EMT) Sensing Panel Enables Precise Differentiating of Cancer Cells at Various EMT Stages.

Epithelial-mesenchymal transition (EMT) is a complex process that plays a critical role in tumor progression. In this study, we present an EMT sensing panel for the classification of cancer cells at different EMT stages. This sensing panel consists of three types of fluorescent probes based on boronic acid-functionalized carbon-nitride nanosheet (BCN) derivatives. The selective response toward different EMT-associated biomarkers, namely, EpCAM, N-cadherin, and sialic acid (SA), was achieved by conjugating the corresponding antibodies to each BCN derivative, whereas the rare-earth-doping ensures simultaneous sensing of the three biomarkers with fluorescent emission of the three probes at different wavelengths. Sensitive sensing of the three biomarkers was achieved at the protein level with LODs reaching 1.35 ng mL-1 for EpCAM, 1.62 ng mL-1 for N-cadherin, and 1.54 ng mL-1 for SA. The selective response of these biomarkers on the cell surface also facilitated sensitive detection of MCF-7 cells and MDA-MB-231 cells with LODs of 2 cells/mL and 2 cells/mL, respectively. Based on the simultaneous sensing of the three biomarkers on cancer cells that underwent different extents of EMT, precise discrimination and classification of cells at various EMT stages were also achieved with an accuracy of 93.3%. This EMT sensing panel provided a versatile tool for monitoring the EMT evolution process and has the potential to be used for the evaluation of the EMT-targeting therapy and metastasis prediction.

ECL cytosensor for sensitive and label-free detection of circulating tumor cells based on hierarchical flower-like gold microstructures

The development of sensitive and efficient cell sensing strategies to detect circulating tumor cells (CTCs) in peripheral blood is crucial for the early diagnosis and prognostic assessment of cancer clinical treatment. Herein, an array of hierarchical flower-like gold microstructures (HFGMs) with anisotropic nanotips was synthesized by a simple electrodeposition method and used as a capture substrate to construct an ECL cytosensor based on the specific recognition of target cells by aptamers. The complex topography of the HFGMs array not only catalyzed the enhancement of ECL signals, but also induced the cells to generate more filopodia, improving the capture efficiency and shortening the capture time. The effect of topographic roughness on cell growth and adhesion propensity was also investigated, while the cell capture efficiency was proposed to be an important indicator affecting the accuracy of the ECL cytosensor. In addition, the capture of cells on the electrode surface increased the steric hindrance, which caused ECL signal changes in the Ru(bpy)32+ and TPrA system, realizing the quantitative detection of MCF-7 cells. The detection range of the sensor was from 102 to 106 cells mL−1 and the detection limit was 18 cells mL−1. The proposed detection method avoids the process of separation, labeling and counting, which has great potential for sensitive detection in clinical applications.

A Cascaded Phase-Transfer Microfluidic Chip with Magnetic Probe for High-Activity Sorting, Purification, Release, and Detection of Circulating Tumor Cells.

Microfluidic chips have emerged as a promising tool for sorting and enriching circulating tumor cells (CTCs) in blood, while the efficacy and purity of CTC sorting greatly depend on chip design. Herein, a novel cascaded phase-transfer microfluidic chip was developed for high-efficiency sorting, purification, release, and detection of MCF-7 cells (as a model CTC) in blood samples. MCF-7 cells were specifically captured by EpCAM aptamer-modified magnetic beads and then introduced into the designed cascaded phase-transfer microfluidic chip that consisted of three functional regions (sorting, purification, and release zone). In the sorting zone, the MCF-7 cells moved toward the inner wall of the channel and entered the purification zone for primary separation from white blood cells; in the purification zone, the MCF-7 cells were transferred to the phosphate-buffered saline flow under the interaction of Dean forces and central magnetic force, achieving high purification of MCF-7 cells from blood samples; in the release zone, MCF-7 cells were further transferred into the nuclease solution and fixed in groove by the strong magnetic force and hydrodynamic force, and the continuously flowing nuclease solution cleaved the aptamer on the trapped MCF-7 cells, causing gentle release of MCF-7 cells for subsequent inductively coupled plasma mass spectrometry (ICP-MS) detection or further cultivation. By measurement of the endogenous element Zn in the cells using ICP-MS for cell counting, an average cell recovery of 84% for MCF-7 cells was obtained in spiked blood samples. The developed method was applied in the analysis of real blood samples from healthy people and breast cancer patients, and CTCs were successfully detected in all tested patient samples (16/16). Additionally, the removal of the magnetic probes on the cell surface significantly improved cell viability up to 99.3%. Therefore, the developed cascaded phase-transfer microfluidic chip ICP-MS system possessed high integration for CTCs analysis with high cell viability, cell recovery, and purity, showing great advantages in early clinical cancer diagnosis.

Electrochemical biosensing based on folic acid-triazine-grafted reduced graphene oxide: a highly selective breast cancer cell sensor.

Based on the results of this research, a new electrochemical sensor has been developed to detect human breast cancer cells (MCF-7). A folic acid (FA)-functionalized triazine-grafted reduced graphene oxide (RGOTrz) was used as the modifier of a glassy carbon electrode (GCE) for application as the sensing element. The composition of the resulting FA-RGOTrz/GCE was investigated using XRD (X-ray diffraction), FT-IR (Fourier-transform infrared) spectroscopy, SEM (scanning electron microscopy) and UV-vis spectroscopy studies. CV (cyclic voltammetry) and EIS (electrochemical impedance spectroscopy) techniques were also used to characterize the electrochemical proficiency of the new electrode. Further, MCF-7 cancer cells were examined in solutions of phosphate buffer and [Fe(CN)6]3-/4- as a suitable supporting electrolyte and a useful probe, respectively. The FA-RGOTrz/GCE provides a suitable substrate to reversible redox reactions and provides good electrochemical signals after binding to cancer cells. DPV (differential pulse voltammetry) results indicated that the binding of folate receptor (FR) in the MCF-7 cell to the RGOTrz-modified electrode, in the presence of [Fe(CN)6]3-/4-, reduced folic acid, diminished electron transfer and collapsed the current signal. During the measured flow, a detection limit of 50 human breast cancer cells per milliliter was obtained. The FA-RGOTrz/GCE, with its unique structural design, significantly increases the electron transfer and electrochemical activity towards the detection of MCF-7 cells. This FA-RGOTrz/GCE sensor, due to its special structure, shows high sensitivity to FR in MCF-7 cells and excellent, reliable and satisfactory performance and a great promise for use in industries and medical field.

Highly sensitive photoelectrochemical sensing platform based on PM6:Y6 p-n heterojunction for detection of MCF-7 cells

Development of novel photoactive materials is of great significance for improving the analytical performance of photoelectrochemical (PEC) biosensors. Herein, sensitive PEC biosensor was developed based on organic PM6:Y6 p-n heterojunction as photoactive matrix for circulating tumor cells (CTCs) detection. Y6, as organic acceptor that combines with the organic donor PM6 forms p-n heterojunction promoted separation of photo-generated charges with high charge transfer efficiency, resulting in the enhancement of photocurrent intensity. The detection of CTCs was achieved through the traditional “sandwich” protocol. Magnetic nanobeads (MNs) decorated with anti-epithelial cell attachment molecule antibody (anti-EpCAM) were used for capturing and separating CTCs, while the Au-aptamer probe and silver staining reaction were designed for dual signal amplification. The localized surface plasmon resonance (LSPR) of gold nanoparticles (Au NPs), and silver nanoparticles (Ag NPs) that generated by silver staining reaction improved photocurrent response of PEC sensor. This PEC biosensor was applied to detect MCF-7 and displayed an ultra-low detection limit of 9 cell mL−1 and linear range from 10 to 10000 cell mL−1. This work explored a path for the application of organic semiconductors as photoactive materials in PEC sensing, which may find broad applications for detecting varied analytes.

Antifouling Electrochemical Biosensor Based on the Designed Functional Peptide and the Electrodeposited Conducting Polymer for CTC Analysis in Human Blood.

Circulating tumor cells (CTCs) are considered reliable cancer biomarkers for the liquid biopsy of many types of tumors. The direct detection of CTCs in human blood with normal biosensors, however, remains challenging because of severe biofouling in blood that contains various proteins and a large number of cells. Herein, we report the construction of an antifouling electrochemical biosensor capable of assaying CTCs directly in blood, based on a designed multifunctional peptide and the electrodeposited conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT). The designed peptide possesses antifouling capability in complex biological media and specific recognition ability to capture breast cancer cells MCF-7. Meanwhile, electrodeposited PEDOT can promote electron transfer at the sensing interface, improve the signal-to-noise ratio for the detection, and thus enhance the sensitivity of the biosensor. The integration of the multifunctional peptide and conducting polymer PEDOT ensures that the developed biosensor is able to perform directly in blood samples without purification or separation. The antifouling electrochemical biosensor for the detection of MCF-7 cells exhibits a wide linear range over 4 orders, with a limit of detection (LOD) of 17 cells mL-1. More interestingly, even when performing in 25% human blood, the biosensor still retains a linear response with an LOD of 22 cells mL-1, without suffering significantly from biofouling in real blood. This work provides a promising strategy for the direct analysis of CTCs in human blood without a complicated pretreatment, and it may find practical application in the liquid biopsy of cancers.

Recognition and sensitive detection of CTCs using acontrollable label-free electrochemical cytosensor.

An excellent atomic layer deposition (ALD) method was adopted for the controllable systhesis of a xFe2O3-nPt (or nPt-xFe2O3)-coated graphene nanostructure (xFe2O3-nPt@graphene). The produced nanomaterials have beencharacterized by transmission electron microscopy (TEM), cyclic voltammetry (CV), and X-ray photoelectron spectroscopy (XPS). It is shown that xFe2O3 and nPt were effectively tailored and deposited on the graphene. A simple, rapid, and sensitive electrochemical cytosensor based on the controllable nanomaterials was successfully developed for MCF-7 cells detection by combining the high affinity and specificity of an aptamer. The prepared cytosensor displays a linear response to MCF-7 in the concentration range 18 to 1.5 × 106 cell mL-1 with the detection limit of 6 cell mL-1 (at an S/N of 3). This cytosensor was applied to detect circulating tumor cells (CTCs) in patient blood and the results were satisfied. The experimental results indicate thatthe proposed controllable electrochemical cytosensor is highly-sensitive, and convenient for clinical detection of breast CTCs. Graphical abstract.

High luminous efficiency Au@CDs for sensitive and label-free electrochemiluminescent detection of circulating tumor cells in serum

In this work, new gold@carbon dots nanoalloys (Au@CDs) were synthesized by directly heating carbon dots (CDs) and HAuCl4 aqueous solution to boiling. The as-synthesized Au@CDs exhibited 12-fold enhancement in the ECL emission compared to the single CDs. The high luminous efficiency Au@CDs was further used to fabricate an ECL cytosensor for the direct detection of circulating tumor cells (CTCs) in serum by ligation of a cell-specific aptamer. Briefly, human mucin1 protein (MUC1) aptamer was immobilized onto the surface of Au@CDs on the electrode for capturing MUC1-positive MCF-7 cells (a type of CTCs). On the basis of the increased steric hindrance, the captured MCF-7 cells can be quantitatively detected. Our strategy was free from complicated separation and labeling treatment, and realized the detection of MCF-7 cells (a type of CTCs) from 100 to 10,000 cells/mL with a detection limit of 34 cells/mL, offering promising applications in ultrasensitive routine clinical analysis and point-of-care testing.

A digital method for the detection of MCF-7 cells using magnetic microparticles-DNA-enzyme

Interaction between enzymes and beads due to the nonspecific binding is a strong limitation to digital enzyme-linked immunosorbent assay (ELISA). To overcome the limitation and broaden the application in digital ELISA, we herein introduce the aptamer, which is capable of binding various molecules with high affinity and specificity, to replace the role of antibody for recognizing target molecules. We construct a digital sensor that regulated by magnetic microparticles-DNA-enzyme (MMPs-DNA-enzyme) system for MCF-7 cells detection. This system is consisting of enzyme-labeled aptamer, and nucleic acids modified-magnetic microparticles that can lock aptamer-labeled enzyme, preventing the negative reaction in the absence of target MCF-7 cells. The presence of target MCF-7 cells can trigger the release of enzyme-labeled aptamer from magnetic microparticles because aptamer and target protein react specifically, resulting in strong fluorescence signal. We successfully applied this digital detection method in the detection of MCF-7 cells by using the aptamer of mucin 1 protein (MUC 1) and epithelial cell adhesion molecule (EpCAM). This designed method can realize MCF-7 cells sensitive detection with a limit of detection of 2 cells/μL. Since this method can eliminate the nonspecific binding compared to traditional digital ELISA, it provides a new development for digital technology.

Colorimetric assay of apoptosis through in-situ biosynthesized gold nanoparticles inside living breast cancer cells

Abnormalities in apoptosis (More or less than normal rate) is a central factor to detect many human disorders such as many types of cancer and to show therapeutic potential of drugs. During apoptosis, oxidation of reduced gluthation (GSH) to its oxidized form, GSSG, results in a decreased GSH to GSSG ratio. Here, we used altered GSH/GSSG redox state and the release of Cyt c from mitochondria to cytosol as an indicator for apoptosis assay. This study reports a visual method for cell apoptosis assay through in-situ biosynthesized gold nanoparticles (AuNPs) inside livingcells, only after adding a sufficient amount of gold ion. After incubation of apoptotic and non-apoptotic cells with chloroauric acid solution, high level of GSH act as reducing agent in formation of AuNPs using thiol inside living non-apoptotic cells. While in the apoptotic cells, what's happening is based on changes in plasmonic coupling between AuNPs embedded along the oxidized gluthation and Cyt c aggregates in cytosol which causes color changes from red to purple. In this study, we successfully reported cell-based (inside a living cells) and cell free (cell lysis) methods for apoptosis assay of breast cancer cells and we achieved very good results in comparison with a standard apoptosis assay procedure. The linear range for MCF-7 cells detection from 30 to 3 × 105 cells/ml was obtained with a detection limit of 30 cells. In addition, the proposed approach is applicable to detect other apoptotic cells.

Gold nanoparticles conjugated to bimetallic manganese(II) and iron(II) Prussian Blue analogues for aptamer-based impedimetric determination of the human epidermal growth factor receptor-2 and living MCF-7 cells.

An aptamer-based assay is described for the determination of trace levels of the cancer marker human epidermal growth factor receptor-2 (HER2) and living MCF-7 cells. The method is based on the use of a bimetallic MnFe Prussian blue analogue coupled to gold nanoparticles (MnFePBA@AuNP). Compared to pristine MnFe PBA nanocubes, the series of MnFePBA@AuNP exhibits a core-shell spherical nanostructure, and the shell thickness decreases from 99.9nm down to 49.3nm on increasing the fraction of AuNPs. The composite was placed on a gold electrode and incubated with the aptamer solution through electrostatic interaction. Then the modified electrode was employed to detect HER2 and MCF-7 cells using [Fe(CN)6]3-/4- as redox probe and displays good responses to both of them. Electrochemical impedance spectroscopy data show that the signal variation between each step during the whole procedure for the HER2 and MCF-7 cells detection can be embodied as the resistance value change between the [Fe(CN)6]3-/4- and electrode surface. The assay has a very low detection limit (0.247pg∙mL-1) and works in the 0.001-1.0ng∙mL-1 HER2 concentration range. It was also used to sense HER2 in MCF-7 cells, and this results in an assay that works within the 500-5 × 104 cell∙mL-1 cell concentration range and a 36 cell∙mL-1 detection limit. Furthermore, the aptamer-based assay is selective, acceptably reproducible, stable, and well feasible for the detection of HER2 and living MCF-7 cells in human serum. Graphical abstract Schematic of an electrochemical aptasensor based on the bimetallic MnFe Prussian blue analogue (MnFe PBA) coupling with gold nanoparticles (represented by MnFePBA@AuNPs). Itwas employed as the aptasensor for human epidermal growth factor receptor-2 (HER2), and living MCF-7 cells.

Synergistic bio-recognition/spatial-confinement for effective capture and sensitive photoelectrochemical detection of MCF-7 cells.

In this communication, a synergistic strategy of bio-recognition/spatial-confinement has been proposed for the effective capture of cancer cells and sensitive photoelectrochemical detection with the lowest limit of detection of 2 cells per mL. The synergistic strategy opens up a new avenue for rational combination of bio-molecule recognition units and nanostructures for bio-detection.

An improved class of fluorescent silica nanoparticles for indirect immunofluorescence detection of MCF-7 cells

In this work, we have developed an efficient method based on silica fluorescent dye-doped nanoparticles and second antibody for cancer cell labeling. The dye-doped silica nanoparticles were synthesized by the reverse microemulsion method with the conjugate of 3-aminopropyltriethoxysilane and rhodamine B isothiocynate. A PEG with flexible long chain as the bridge was introduced onto the surface of the nanoparticle via cyanogens bromide method. The second antibody, goat anti-rabbit IgG, was conjugated on the surface of the PEG-terminal modified silica fluorescent nanoparticles by covalent binding to the PEG linkers via the EDC/sulfo-NHS method. The concentrations of goat anti-rabbit IgG covering the nanoparticles were quantified via the Bradford method. The silica fluorescent nanoparticles functionalized with rabbit anti-MUC1 antibody were employed as bioprobes for the recognition of MUC1 protein in human breast carcinoma molecules MCF-7 cells. Compared with fluorescent dye labeled IgG, the fluorescent nanoprobes display dramatically increased photostability.

An Investigation of Anticancer Effects of Doxorubicin and Calcitriol Combination on MCF-7 Cells

<strong>Objectives</strong>: This study aimed to identify a substance that both increases the efficiency and decreases the dose of doxorubicin. Doxorubicin has considerable cardiac side effects at certain doses when used treating breast cancer. Calcitriol, one of the vitamin D analogs considered to have antiproliferative effects, was selected, and its cytotoxic effects on the human breast cancer cell line MCF7 were investigated in combination with doxorubicin. <br> <strong>Materials and Methods</strong>: MCF-7 cell line was treated with calcitriol in real time for 72 h in x-CELLigence. The antiproliferative optimal dose of calcitriol was determined by time-dependent cell index graph plotted using The xCELLigence Real-Time Cell Analysis (RTCA) software program. The combination of different doses of doxorubicin and this optimal dose of calcitriol was used to treat the MCF-7 cell line. Then, Sulforhodamine-B (SRB) assay was conducted, and spectrophotometric measurements were performed for cytotoxicity assay. The results of these spectrophotometric measurements were analyzed by Student’s -test. <br> <strong>Results</strong>: The optimal antiproliferative calcitriol dose detection of MCF-7 cells was performed using the time-dependent cell index graph RTCA software program. Spectrophotometric measurements obtained using the protein-staining sulforodamine B (SRB) assay for cytotoxicity determination were statistically evaluated by the Student’s t-test using the GraphPad Prism program. The optimal dose of calcitriol was determined to be 250 nM. Different doses of doxorubicin (1.84-0.92 µM), calcitriol (250 nM), and calcitriol without the MCF-7 cell line were then used for detecting the cytotoxic effect. The combination of 0.46 µM doxorubicin and the optimal dose of calcitriol was found to be cytotoxic compared with other doses (p=0.0087); however, it was not as effective as the dose reduction obtained when using doxorubicin. <br> <strong>Conclusion</strong>: The combined use of doxorubicin with calcitriol was found to have no significant effect in reducing the doses presently being used. Hence, it is too early to state that a combination of vitamin D and doxorubicin in breast cancer treatment will not have any beneficial effects. Other vitamin D analogs might be potential candidates for breast cancer treatment in further studies.

Polyhedral-AuPd nanoparticles-based dual-mode cytosensor with turn on enable signal for highly sensitive cell evalution on lab-on-paper device

A novel dual-mode cytosensor based on polyhedral AuPd alloy nanoparticles (PH-AuPd NPs) and three-dimentional reduced graphene oxide (3D-rGO) was constructed for highly sensitive detection of MCF-7 cells. The 3D-rGO was in situ synthesized on the paper working electrode (PWE) by a pollution-free hydrothermal method, increasing the specific surface area and further facilitating the modification of Au nanoparticles (AuNPs). After modified with AuNPs, the Au@ 3D-rGO/PWE was then functionalized by aptamer H1 to trap MCF-7 cells. To construct the cytosensor, PH-AuPd NPs was prepared as a novel catalytic material, and further modified with aptamer H2 for recognizing MCF-7 cells. With the occurrence of efficient recognition of MCF-7 cells, PH-AuPd NPs were bound onto the surface of the cells, and could catalyze H2O2 to generate •OH, leading to an amplified electrochemical signal. Meanwhile, as the electrolyte solution flowed, the •OH are transferred outward to the colorimetric detection zone, and catalyzed a chromogenic substrate TMB forms a colored product. The electrical signal measurement and colorimetric detection were carried out on a compatibly designed lab-on-paper device (LPD), realizing a dual-mode signal readout. This paper-based dual-mode cytosensor provided a relatively low detection limit of 20 cells mL−1 and a sensitive detection from 50 cells mL−1 to 107 cells mL−1 for MCF-7 cells, providing a reliable pathway of sensitively detecting cancer cells in clinical applications.

Ultrasensitive electrochemiluminescence assay of tumor cells and evaluation of H2O2 on a paper-based closed-bipolar electrode by in-situ hybridization chain reaction amplification

In this manuscript, a disposable paper-based analytical device comprised of a closed bipolar electrode (BPE) was fabricated for the ultrasensitive electrochemiluminescence (ECL) detection of intracellular H2O2 and the number of cancer cells. In this approach, wax printing was used to fabricated reaction zone, and carbon ink-based BPE and driving electrodes were screen-printed into the paper. AuPd nanoparticles (NPs), which served as a carrier of the capture aptamer and as the catalyst for the ECL reaction of luminol and H2O2, were used to modify the BPE. Luminol/Au NPs were attached to the surface of the captured cells via hybridation chain reaction with two hairpin structure DNA labelled luminol/Au NPs. In the stimulation of phorbol myristate acetate, The coreactant H2O2 was released from the target cells. The ECL response of the luminol-H2O2 system was related to the number of cancer cells in the testing buffer, which served as a quantitative signal for the determination of cancer cells and the concentration of H2O2. In order to decrease the external voltage, K3[Fe(CN)6] was introduced in the cathode resevoir of BPE because it gained electrons at the cathode more easily than oxygen. The ECL intensity was quantitatively related to the concentration of MCF-7 in the range of 1.0 × 102–1.0 × 107 cells/mL. The detection limit was 40 cells/mL and it showed good specificity for cells with high overexpression of mucin-1 receptor, it was concluded that the developed protocol could be effectively utilized for the detection of MCF-7 cells.

Breast cancer cells synchronous labeling and separation based on aptamer and fluorescence-magnetic silica nanoparticles

In this work, an efficient method based on biotin-labeled aptamer and streptavidin-conjugated fluorescence-magnetic silica nanoprobes (FITC@Fe3O4@SiNPs-SA) has been established for human breast carcinoma MCF-7 cells synchronous labeling and separation. Carboxyl-modified fluorescence-magnetic silica nanoparticles (FITC@Fe3O4@SiNPs-COOH) were first synthesized using the Stöber method. Streptavidin (SA) was then conjugated to the surface of FITC@Fe3O4@SiNPs-COOH. The MCF-7 cell suspension was incubated with biotin-labeled MUC-1 aptamer. After centrifugation and washing, the cells were then treated with FITC@Fe3O4@SiNPs-SA. Afterwards, the mixtures were separated by a magnet. The cell-probe conjugates were then imaged using fluorescent microscopy. The results show that the MUC-1 aptamer could recognize and bind to the targeted cells with high affinity and specificity, indicating the prepared FITC@Fe3O4@SiNPs-SA with great photostability and superparamagnetism could be applied effectively in labeling and separation for MCF-7 cell in suspension synchronously. In addition, the feasibility of MCF-7 cells detection in peripheral blood was assessed. The results indicate that the method above is also applicable for cancer cells synchronous labeling and separation in complex biological system.