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.

Rapid screening of multi-target antitumor drugs by nonimmobilized tumor cells/tissues capillary electrophoresis.

As there are more target categories on tumor cells/tissues than on receptor-overexpressing cells, and tumor tissues can better simulate TME, we established a new method of screening multi-target antitumor drugs by nonimmobilized tumor cells/tissues capillary electrophoresis under approximately tumor physiological environment. In this method, the natural structure and active conformation of the target proteins on tumor cells/tissues can be well maintained without separation and purification. Therefore, we successfully used this method to study the interactions between the Aidi injection (ADI)/its main components and tumor cells/tissues by optimizing a series of experimental conditions, discovered seven components with binding activity to A549 cells, five of them with specific interaction to tumor tissues, and calculated the binding kinetic parameters (K, ka, kd, and k'). Then, antitumor activity assays in vitro and in vivo were carried out to discover a new drug combination with higher targeting, better pharmaceutical efficacy, and lower toxic side effects. Finally, molecular docking studies were performed to investigate the potential target groups of the interactions between the effective drug combination and A549 cells/tissues. In summary, the method was verified to be valid and feasible, and can be easily transferred to a capillary array electrophoresis for 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.