A Simple Aptamer-Based Nanoconjugate Assay for Diagnosis of Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) as a bone marrow stem cell clonal disease appears from the proliferation of granulocyte cells at all stages of maturation. If the disease diagnosis is not early, patients enter the blastic phase, which decreases their survival rate to 3-6 months. It implies the significance of the early diagnosis of CML. In this study, we introduce a simple array for diagnosis of the K562 cells as the human immortalized myeloid leukemia cell line. The developed aptamer-based biosensor (aptasensor) includes the T2-KK1B10 aptamer strands attached to the surface of mesoporous silica nanoparticles (MSNPs) with the cavities accumulated from rhodamine B and coated by both Ca2+ ions and ATP aptamer. The aptamer-based nanoconjugate can enter the K562 cells through the complexation of the T2-KK1B10 aptamer with the cells. The ATP in the cells and low level of intracellular Ca2+ ion release both the aptamer and ion from the surface of the MSNPs. The liberated rhodamine B results in an increased fluorescence intensity. Fluorescence microscope imaging and flow cytometry histogram display a strong fluorescence emission for the K562 cells (CML cells) exposed to the nanoconjugate in comparison with that for MCF-7 cells. The aptasensor possesses good performance in the blood samples with the advantages of high sensitivity, rapidness, and cost-effectiveness, making it an appropriate tool for the diagnosis of CML disease.

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.

An electrochemiluminescence cytosensor for sensitive detection of HeLa cells based on a signal amplification strategy of Au-NaYF4:Yb,Er nanocomposites

A novel electrochemiluminescence (ECL) cytosensor was proposed for the quantitative detection of HeLa cells (human cervical cancer cells) with the help of a signal amplification strategy. Firstly, the Au-NaYF4:Yb,Er nanocomposites were prepared by a simple in situ hydrothermal method and characterized by transmission electron microscopy (TEM) images, X-ray diffraction (XRD) patterns, UV-vis spectra and Fourier transform infrared (FTIR) spectra. Compared with the bare NaYF4:Yb,Er nanocomposites, the ECL intensity of Au-NaYF4:Yb,Er nanocomposites was greatly enhanced by about 4.2-fold which can be attributed to the good conductivity of gold nanoparticles (Au NPs). The nanocomposites showed high and stable ECL emission, fast response and superior conductivity, all of which were advantageous to the ECL detection. Furthermore, HeLa cells were immobilized on the modified electrode via the interaction between folic acid and a folate receptor present on the cell surface. The ECL cytosensor showed satisfactory sensitive response to HeLa cells in a linear range of 4.25 × 102-4.25 × 105 cells per mL with a low detection limit of 326 cells per mL. The proposed cytosensor had good sensitivity and stability, which can offer a great potential platform for bioassay analysis.

Single Cell Electrochemiluminescence Imaging: From the Proof-of-Concept to Disposable Device-Based Analysis

We report here the development of coreactant-based electrogenerated chemiluminescence (ECL) as a surface-confined microscopy to image single cells and their membrane proteins. Labeling the entire cell membrane allows one to demonstrate that, by contrast with fluorescence, ECL emission is only detected from fluorophores located in the immediate vicinity of the electrode surface (i.e., 1-2 μm). Then, to present the potential diagnostic applications of our approach, we selected carbon nanotubes (CNT)-based inkjet-printed disposable electrodes for the direct ECL imaging of a labeled plasma receptor overexpressed on tumor cells. The ECL fluorophore was linked to an antibody and enabled to localize the ECL generation on the cancer cell membrane in close proximity to the electrode surface. Such a result is intrinsically associated with the unique ECL mechanism and is rationalized by considering the limited lifetimes of the electrogenerated coreactant radicals. The electrochemical stimulus used for luminescence generation does not suffer from background signals, such as the typical autofluorescence of biological samples. The presented surface-confined ECL microscopy should find promising applications in ultrasensitive single cell imaging assays.