Dielectrophoresis: Measurement technologies and auxiliary sensing applications.

Dielectrophoresis (DEP), which arises from the interaction between dielectric particles and an aqueous solution in a nonuniform electric field, contributes to the manipulation of nano and microparticles in many fields, including colloid physics, analytical chemistry, molecular biology, clinical medicine, and pharmaceutics. The measurement of the DEP force could provide a more complete solution for verifying current classical DEP theories. This review reports various imaging, fluidic, optical, and mechanical approaches for measuring the DEP forces at different amplitudes and frequencies. The integration of DEP technology into sensors enables fast response, high sensitivity, precise discrimination, and label-free detection of proteins, bacteria, colloidal particles, and cells. Therefore, this review provides an in-depth overview of DEP-based fabrication and measurements. Depending on the measurement requirements, DEP manipulation can be classified into assistance and integration approaches to improve sensor performance. To this end, an overview is dedicated to developing the concept of trapping-on-sensing, improving its structure and performance, and realizing fully DEP-assisted lab-on-a-chip systems.

Design and synthesis of VEGFR-2 inhibitors based on oleanolic acid moiety.

In this study, twenty-four oleanolic acid (OA) derivatives were rationally designed based on molecule docking studies and their VEGFR-2 inhibitory activities were tested by Homogeneous time-resolved fluorescence (HTRF) method in vitro. All of the synthesized compounds were identified as new compounds, and the structures of these compounds were determined by 1H-NMR and ESI-MS. In the screening for VEGFR-2 inhibitors, compounds I6 and I7 exhibited excellent inhibitory effect. The results indicated that insertion of phenylurea group with a linker at position C-28 of OA can increase the activity against VEGFR-2 significantly. [Formula: see text].

Multifunctional optical fiber sensor for simultaneous measurement of temperature and salinity.

A multifunctional optical fiber sensor fabricated by asymmetric offset splicing is proposed in this Letter. The light is divided into several parts at the offset interface, among which the transmitted light forms the Mach-Zehnder interference (MZI) spectrum while the reflected light forms the Fabry-Perot interference (FPI) spectrum. The online monitoring system is built to create a better light distribution at the offset interface. Theoretical analysis and experimental verification are carried out. The results of the experiment show that the proposed sensor has good characteristics of salinity and temperature, and the salinity sensitivity is as high as -2.4473nm/‰ in the range of 20-40‰; the temperature sensitivity is better than 2.17 nm/°C in the range of 28-48 °C. The two interferometers involved have different responses to temperature and salinity, contributing to the effective elimination of cross-sensitivity. The proposed optical fiber sensor has the benefits of compact size, high sensitivity, and multispectral measurement function.

Transformation of Fe-B@Fe into Fe-B@Ni for efficient photocatalytic hydrogen evolution.

It is highly desirable to develop efficient and cost-effective composite catalysts to replace noble metal Pt for hydrogen evolution reaction (HER). For an excellent HER catalyst, both the adsorption and desorption of intermediate H atoms on it should be easy. However, except metal platinum, most individual species cannot satisfy this requirement. Fe-B is an active HER catalyst with strong ability to adsorb H atoms. In our previous work, we found that when Fe-B alloy was decorated with metal Fe particles (Fe-B@Fe), the resultant composite displayed a significant synergic effect for HER compared to single Fe-B and Fe. The role of the decorated Fe on Fe-B is to improve H2 desorption. Because the desorption of H2 molecule from Ni is easier than from Fe, we expect Fe-B@Ni to be a more efficient HER catalyst than Fe-B@Fe. Herein, we transform Fe-B@Fe into Fe-B@Ni by a facile displacement reaction. As a proof of concept, the as-prepared Fe-B@Ni catalyst exhibits much higher electrocatalytic and photocatalytic activity for hydrogen production than the pristine Fe-B@Fe. At the current density of -100 mA cm-2, the overpotential of Fe-B@Ni in 1.0 mol L-1 KOH is close to that of 20 wt% Pt/C. The highest apparent quantum yield (AQY) for dye-sensitized photocatalytic hydrogen evolution reaches 51% at 420 nm. The possible mechanisms have been proposed. These findings provide new insights for designing and fabricating new HER composite catalysts for electrocatalytic and photocatalytic hydrogen evolution.

Current status of optical fiber biosensor based on surface plasmon resonance.

Surface plasmon resonance (SPR) technology has effectively bolstered optic fiber sensing in fields of life science, clinical diagnosis, medicine, food safety and so on. The current review outlines the research status of fiber optic biosensor based on SPR, and the merits of optical fiber sensor and the development of optical fiber sensor based on SPR are completely covered. An in-depth review of four devices for generating SPR is presented, and optical fiber is finally adopted for a substrate to generate SPR. Different prototypes of optical fiber biosensor based on SPR are meticulously outlined: optical fiber grating biosensor based on SPR and optical fiber structured type biosensor based on SPR, and representative instances from literature are presented to verify the latest advancements in this potentially valuable research avenue. In addition, the sensing performance of different optical fiber structured type biosensor based on SPR are compared. What's more, simultaneous multi-parameter detection and improvement of sensitivity are discussed and summarized. The article concludes identify key challenges and develop orientation of optical fiber biosensor based on SPR.

Prussian Blue Nanoparticle-Labeled Mesenchymal Stem Cells: Evaluation of Cell Viability, Proliferation, Migration, Differentiation, Cytoskeleton, and Protein Expression In Vitro.

Mesenchymal stem cells (MSCs) have been used for the treatment of various human diseases. To better understand the mechanism of this action and the fate of these cells, magnetic resonance imaging (MRI) has been used for the tracking of transplanted stem cells. Prussian blue nanoparticles (PBNPs) have been demonstrated to have the ability of labeling cells to visualize them as an effective MRI contrast agent. In this study, we aimed to investigate the efficiency and biological effects of labeled MSCs using PBNPs. We first synthesized and characterized the PBNPs. Then, iCELLigence real-time cell analysis system revealed that PBNPs did not significantly alter cell viability, proliferation, and migration activity in PBNP-labeled MSCs. Oil Red O staining and Alizarin Red staining revealed that labeled MSCs also have a normal differentiation capacity. Phalloidin staining showed no negative effect of PBNPs on the cytoskeleton. Western blot analysis indicated that PBNPs also did not change the expression of ß-catenin and vimentin of MSCs. In vitro MRI, the pellets of the MSCs incubated with PBNPs showed a clear MRI signal darkening effect. In conclusion, PBNPs can be effectively used for the labeling of MSCs and will not influence the biological characteristics of MSCs.

Calcification: A Disregarded or Ignored Issue in the Gynecologic Tumor Microenvironments.

Although calcification in the gynecologic tumor microenvironments is a common phenomenon, doctors and researchers still disregard or ignore the issue. In fact, this change in the gynecologic tumor microenvironments is clinically significant and a number of studies have reported an association between calcification and gynecological tumor progression. In ovarian cancer, calcification is predominantly psammomatous and largely occurs in serous papillary ovarian tumors. In addition, calcification in ovarian cancer correlated with lower histologic grade and may indicate a poorer survival rate. In uterine fibroids, calcification occurs as a degenerative change and is predictive of a good prognosis. As for endometrial cancer and cervical cancer, calcification rarely occurs in these cancers. The mechanism of calcification in the gynecologic tumor microenvironments is not currently clear. One theory is that calcification occurs due to degeneration of the tumor cells; another theory is that calcification occurs in response to secretions from cells in the tumor microenvironment. Although previous studies have revealed a direct association between calcifications and gynecological tumors, this association has not been fully clarified. To better clarify the significance of calcification in terms of diagnosing and treating gynecological tumors, the associations between calcification and the different histologic stages and prognosis in gynecological tumors should be further studied. In particular, more attention should be paid to the morphological characteristics, chemical nature, and mechanism of calcifications in the gynecological tumor microenvironments.