Mechanical deformation and death of circulating tumor cells in the bloodstream.

The circulation of tumor cells through the bloodstream is a significant step in tumor metastasis. To better understand the metastatic process, circulating tumor cell (CTC) survival in the circulation must be explored. While immune interactions with CTCs in recent decades have been examined, research has yet to sufficiently explain some CTC behaviors in blood flow. Studies related to CTC mechanical responses in the bloodstream have recently been conducted to further study conditions under which CTCs might die. While experimental methods can assess the mechanical properties and death of CTCs, increasingly sophisticated computational models are being built to simulate the blood flow and CTC mechanical deformation under fluid shear stresses (FSS) in the bloodstream.Several factors contribute to the mechanical deformation and death of CTCs as they circulate. While FSS can damage CTC structure, diverse interactions between CTCs and blood components may either promote or hinder the next metastatic step-extravasation at a remote site. Overall understanding of how these factors influence the deformation and death of CTCs could serve as a basis for future experiments and simulations, enabling researchers to predict CTC death more accurately. Ultimately, these efforts can lead to improved metastasis-specific therapeutics and diagnostics specific in the future.

Myosin-independent stiffness sensing by fibroblasts is regulated by the viscoelasticity of flowing actin.

The stiffness of the extracellular matrix induces differential tension within integrin-based adhesions, triggering differential mechanoresponses. However, it has been unclear if the stiffness-dependent differential tension is induced solely by myosin activity. Here, we report that in the absence of myosin contractility, 3T3 fibroblasts still transmit stiffness-dependent differential levels of traction. This myosin-independent differential traction is regulated by polymerizing actin assisted by actin nucleators Arp2/3 and formin where formin has a stronger contribution than Arp2/3 to both traction and actin flow. Intriguingly, despite only slight changes in F-actin flow speed observed in cells with the combined inhibition of Arp2/3 and myosin compared to cells with sole myosin inhibition, they show a 4-times reduction in traction than cells with myosin-only inhibition. Our analyses indicate that traditional models based on rigid F-actin are inadequate for capturing such dramatic force reduction with similar actin flow. Instead, incorporating the F-actin network's viscoelastic properties is crucial. Our new model including the F-actin viscoelasticity reveals that Arp2/3 and formin enhance stiffness sensitivity by mechanically reinforcing the F-actin network, thereby facilitating more effective transmission of flow-induced forces. This model is validated by cell stiffness measurement with atomic force microscopy and experimental observation of model-predicted stiffness-dependent actin flow fluctuation.

A Low-Cost and High-Efficiency Integrated Device toward Solar-Driven Water Splitting.

Achieving the spontaneous evolution of fuel from integrated devices by solar-driven water splitting is an attractive method for renewable energy conversion. However, their widespread implementation is hindered by their immature architectures and inferior performances. Here, we propose a real integrated device consisting of two series-connected perovskite solar cells (PSCs) and two CoP catalyst electrodes, which can be immersed into the aqueous solution directly for solar-driven water splitting. Benefiting from the low-cost and facile encapsulation technique, this integrated device possesses a compact structure and well-connected circuits for the process of charge carriers generation, transfer, and storage. Moreover, although all expensive components in this integrated device are eliminated, the two series-connected carbon-based PSCs still exhibit a high solar-to-electric efficiency of 10.6% as well as the integrated devices display a solar-to-hydrogen efficiency of as high as 6.7%. This integrated device serves as a model architecture toward future development and optimization of the integrated device that can be immersed into the aqueous solution directly for water splitting.