Quantitative Imaging of pN Intercellular Force and Energetic Costs during Collective Cell Migration in Epithelial Wound Healing.

Collective cell migration plays a key role in tissue repair, metastasis, and development. Cellular tension is a vital mechanical regulator during the force-driven cell movements. However, the contribution and mechanism of cell-cell force interaction and energetic costs during cell migration are yet to be understood. Here, we attempted to unfold the mechanism of collective cell movement through quantification of the intercellular tension and energetic costs. The measurement of pN intercellular force is based on a "spring-like" DNA-probe and a molecular tension fluorescence microscopy. During the process of wound healing, the intercellular force along with the cell monolayer mainly originates from actin polymerization, which is strongly related to the cellular energy metabolism level. Intracellular force at different spatial regions of wound and the energetic costs of leader and follower cells were measured. The maximum force and energy consumption are mainly concentrated at the wound edge and dynamically changed along with different stages of wound healing. These results indicated the domination of leader cells other than follower cells during the collective cell migration.

Silver decahedral nanoparticles empowered SPR imaging-SELEX for high throughput screening of aptamers with real-time assessment.

A highly efficient method for aptamer screening with real-time monitoring of the SELEX process was described by silver decahedra nanoparticles (Ag10-NPs) enhanced surface plasmon resonance imaging (SPRI). A microarray chip was developed by immobilization of target protein (Lactoferrin (Lac)) and control proteins (α-lactalbumin (α), ß-lactoglobulin (ß), casein, and bovine serum albumin (BSA)) on the biochip surface. Ag10-NPs were conjugated with an ssDNA library (lib) (Ag10-NPs-library) that consisted of a central 40 nt randomized sequence and a 20 nt fixed primer sequence. Introduction of the Ag10-NPs-library to the SPRI flow channels drastically increased the sensitivity of SPRI signal for real-time monitoring of SELEX. The work allows rapid screening of potential targets, and yields nine aptamers with high affinity (nanomolar range) for Lac after only six-rounds of selection. The aptamer Lac 13-26 was then further tested by SPRI, and the results demonstrated that the aptamer had the capacity to be ultra-sensitive for specific detection of Lac. The novel SPRI-SELEX method demonstrated here showed many advantages of real-time evaluation, high throughput, and high efficiency.

Portable thermo-powered high-throughput visual electrochemiluminescence sensor.

This paper describes a portable thermo-powered high-throughput visual electrochemiluminescence (ECL) sensor for the first time. This sensor is composed of a tiny power supply device based on thermal-electrical conversion and a facile prepared array electrode. The ECL detection could be conducted with thermo-power, which is easily accessible. For example, hot water, a bonfire, or a lighted candle enables the detection to be conducted. And the assay can be directly monitored by the naked eye semiquantitatively or smart phones quantitatively. Combined with transparent electrode and array microreactors, a portable high-throughput sensor was achieved. The portable device, avoiding the use of an electrochemical workstation to generate potential and a photomultiplier tube to receive the signal, is not only a valuable addition for traditional methods but also a suitable device for field operation or point-of-care testing.

Microchip device with 64-site electrode array for multiplexed immunoassay of cell surface antigens based on electrochemiluminescence resonance energy transfer.

This paper describes a novel on-chip microarray platform based on an electrochemiluminescence resonance energy transfer (ECL-RET) strategy for rapid assay of cancer cell surface biomarkers. This platform consists of 64 antigen-decorated CdS nanorod spots with the diameter of 1.0 cm uniformly distributed on 16 indium tin oxide (ITO) strips, which is coated with a multichannel decorated polydimethylsiloxane (PDMS) slice to realize multiplexed determination of antigens. To shorten the immune reaction time in the microchannels and simplify the device, magnetic stirring and four-channel universal serial bus (USB) ports for plug-and-play were used. When Ru(bpy)(3)(2+) labeled antibodies were selectively captured by the corresponding antigens on the CdS nanorod spot array, ECL-RET from the CdS nanorod (donor) by cathodic emission in the presence of K(2)S(2)O(8) to Ru(bpy)(3)(2+) (acceptor) occurred. With signal amplification of Ru(bpy)(3)(2+) and competitive immunoassay, carcinoembryonic antigen (CEA), α-fetoprotein (AFP), and prostate specific antigen (PSA) as models were detected on this microfluidic device via recording the increased ECL-RET signals on electrode surfaces. Furthermore, this multiplexed competitive immunoassay was successfully used for detecting cancer cell surface antigens via the specific antibody-cell interactions and cell counting via cell surface receptors and antigens on the CdS nanorod surface. This platform provides a rapid and simple but sensitive approach with microliter-level sample volume and holds great promise for multiplexed detection of antigens and antigen-specific cells.