Novel Cells-Based Electrochemical Sensor for Investigating the Interactions of Cancer Cells with Molecules and Screening Multitarget Anticancer Drugs.

A novel, effective, and label-free electrochemical sensor was constructed for investigating the interactions between cancer cells and molecules, based on targeted cancer cells immobilized on a bilayer architecture of N-doped graphene-Pt nanoparticles-chitosan (NGR-Pt-CS) and polyaniline (PANI). The interactions between folic acid (FA, positive control) and dimethyl sulfoxide (DMSO, negative control) and the choice of targeted cells, HepG2 and A549 cells, were investigated by measuring the current change of the sensor to [Fe(CN)6]3-/4- before and after interactions, and the binding constants were calculated to be 1.37 × 105 and 1.92 × 105 M-1 by sensing kinetics. Furthermore, 18 main components from Aidi injection (ADI) were studied to screen compounds that have interactions with different targeted cancer cells including HepG2 and A549 cells. The potential target groups of the interactions between screened active compounds and targeted cancer cells were analyzed through computer-aided molecular docking. In this sensing system, molecules did not require electrochemical activity, and different targeted cancer cells could be immobilized on the modified electrode surface, truly reflecting the categories and numbers of targets. Additionally, the proposed sensor specifically circumvented the current paradigm in most cells-based electrochemical sensors for screening drugs, in which the changes in cell behavior induced by drugs are monitored. This study provided a novel, simple, and generally applicable method for exploring the interaction of molecules with cancer cells and screening multitarget drugs.

Detection of membrane receptors on per tumor cell by nonimmobilized cell capillary electrophoresis and a mathematic model.

Folate receptors (FRs) are a class of valuable therapeutic target which is highly expressed on a variety of cancers. The accurate detection of the expression of FRs in different cells is conducive to improve the accuracy of FR targeted tumor therapy. Herein, a method based on nonimmobilized cell capillary electrophoresis (NICCE) combined with a mathematic model to quantify FRs on each single tumor cell was developed. At first, we studied the interactions between FA and A549, HT-29, HepG2, and U87MG cells by NICCE respectively, and calculated the kinetic parameters (Ka, k', ka, and kd). Next, we established a mathematic model to accurately determine the number of moles of FRs on per A549, HT-29, HepG2, and U87MG cell for the first time, that were (10.44 ± 0.53) × 10-19 mol, (34.32 ± 1.33) × 10-19 mol, (337.14 ± 10.11) × 10-19 mol, and (37.31 ± 2.13) × 10-19 mol. Then, these re-sults were proved to be consistent with the results of enzyme-linked immunosorbent assay (ELISA). Therefore, this method is simple, rapid, sensitive, and without protein separation or purification, which is expected to achieve clinical detection of cell membrane receptor expression level of cell membrane receptors on a single cell, which may be greatly beneficial to further clinical diagnosis and therapy.

A novel strategy for rapidly and accurately screening biomarkers based on ultraperformance liquid chromatography-mass spectrometry metabolomics data.

We reported a novel strategy for rapidly and accurately screening biomarkers based on ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) metabolomics data. First, the preliminary variables were obtained by screening the original variables using method validation. Second, the variables were selected from the preliminary variables and formed the variable sets by testing different thresholds of single factor (variable importance in projection (VIP), fold change (FC), the area under the receiver operating characteristic curve (AUROC), and -ln(p-value)). Then the partial least squares-discriminant analysis (PLS-DA) models were performed. The best threshold of each factor, and the corresponding variable set were found by comparing the models' R2X, R2Y, and Q2. Third, the second-step-obtained variable sets were further screened by multi-factors. The best combination of the multi-factors, and the corresponding variable set were found by comparing R2X, R2Y, and Q2. The expected biomarkers were thus obtained. The proposed strategy was successfully applied to screen biomarkers in urine, plasma, hippocampus, and cortex samples of Alzheimer's disease (AD) model, and significantly decreased the time of screening and identifying biomarkers, improved the R2X, R2Y, and Q2, therefore enhanced the interpreting, grouping, and predicting abilities of the PLS-DA model compared with generally-applied procedure. This work can provide a valuable clue to scientists who search for potential biomarkers. It is expected that the developed strategy can be written as a program and applied to screen biomarkers rapidly, efficiently and accurately.

Rapid screening of anti-tumor metastasis drugs targeting integrin macrophage antigen-1 using immobilized cell capillary electrophoresis.

In this research a method called immobilized cell capillary electrophoresis (ICCE) was established under approximately physiological conditions for rapid screening of anti-tumor metastasis drugs targeting integrin macrophage antigen-1 (MAC-1). In this method, separation and purification of the target receptors on cell membranes was unnecessary, thus, maintaining their natural conformation and bioactivity. MAC-1-, CD11b-, or CD18-overexpressing HEK293 cells (human embryonic kidney) were cultured and immobilized on the inner wall of capillaries as stationary phase, and their interactions with lactosyl derivative Gu-4 (positive control)/dimethylsulfoxide (DMSO; negative control) were studied using ICCE. Using this method, 29 phenylethanoid glycosides from Cistanches Herba were screened, and the binding kinetic parameters (K, ka, kd, and k') of active compounds were calculated, and the specific subunits of MAC-1 were determined. Then, molecular docking studies were performed to discover the direct interaction sites between active compounds and MAC-1, and the order of Glide-calculated Emodel value obtained from the molecular docking study is consistent with that of the binding constants obtained using ICCE. Finally, pharmaceutical efficacy assays in vitro and in vivo were carried out to show that the anti-tumor metastasis activity of the active compound had better pharmaceutical efficacy and lower toxic side effects. The method was verified to be valid and practical for further use, and it is expected that it will be transferred to capillary array electrophoresis for use in high-throughput drug screening.

MNPs@anionic MOFs/ERGO with the size selectivity for the electrochemical determination of H2O2 released from living cells.

Herein, the ternary composites, ultrasmall metal nanoparticles encapsulated in the anionic metal-organic frameworks/electrochemically reduced graphene oxide (MNPs@Y-1, 4-NDC-MOF/ERGO, M = Ag, Cu) are constructed by a cationic exchange strategy and an electrochemical reduction process for the electrochemical determination of H2O2. Both AgNPs@Y-1, 4-NDC-MOF/ERGO and CuNPs@Y-1, 4-NDC-MOF/ERGO display excellent electrocatalytic activity toward H2O2, but the former is superior to the latter. Such a difference in electrocatalytic activity can be explained by the characterization measurements, and the results manifest MNPs@Y-1, 4-NDC-MOF/ERGO (M = Ag, Cu) electrocatalysts have subequal MNPs sizes and electrochemical surface areas, but different electron transfer rate constants. The AgNPs@Y-1, 4-NDC-MOF/ERGO sensor shows a linear detection range from 4 to 11,000 µM with the detection limit of 0.18 µM. Moreover, MNPs@Y-1, 4-NDC-MOF/ERGO (M = Ag, Cu) exhibit excellent anti-interference performance and can be used for the detection of H2O2 released from living cells. The proposed sensor takes full advantage of the catalytic property of MNPs, the size selectivity of Y-1, 4-NDC-MOF, and the fast electron transport effect of ERGO. Thus, the MNPs@Y-1, 4-NDC-MOF/ERGO/GCE (M = Ag, Cu) can be utilized to detect oxidase activities by monitoring H2O2 produced in the presence of substrate and oxidase, and it is expected that composites with the molecular sieving effect and catalytic activity can be widely applied for catalysis, biomedicine, and biosensing fields.