Mechanobiology is an emerging field at the interface of biology and mechanics, investigating the roles of mechanical forces within biomolecules, organelles, cells, and tissues. As a highlight, the recent advances of micropipette-based aspiration assays and dynamic force spectroscopies such as biomembrane force probe (BFP) provide unprecedented mechanobiological insights with excellent live-cell compatibility. In their classic applications, these assays measure force-dependent ligand–receptor-binding kinetics, protein conformational changes, and cellular mechanical properties such as cortical tension and stiffness. In recent years, when combined with advanced microscopies in high spatial and temporal resolutions, these biomechanical nanotools enable characterization of receptor-mediated cell mechanosensing and subsequent organelle behaviors at single-cellular and molecular level. In this review, we summarize the latest developments of these assays for live-cell mechanobiology studies. We also provide perspectives on their future upgrades with multimodal integration and high-throughput capability.

Cells sense and respond to mechanical stimuli for activation, proliferation, migration, and differentiation. The associated mechanosensing and biomechanical properties of cells and tissues are significantly implicated in the context of cancer, fibrosis, dementia, and cardiovascular diseases. To gain more mechanobiology insights, dynamic force spectroscopies (DFSs), particularly optical tweezers (OT), have been further advanced to enable in situ force measurement and subcellular manipulation from the outer cell membrane to the organelles inside of a cell. In this review, we first explain the classic OT-DFS rationales and discuss their applications to protein biophysics, extracellular biomechanics, and receptor-mediated cell mechanosensing. As a non-invasive technique, optical tweezers’s unique advantages in probing cytoplasmic protein behaviors and manipulating organelles inside living cells have been increasingly explored in recent years. Hereby, we then introduce and highlight the emerging OT rationales for intracellular force measurement including refractive index matching, active–passive calibration, and change of light momentum. These new approaches enable intracellular OT-DFS and mechanical measurements with respect to intracellular motor stepping, cytosolic micro-rheology, and biomechanics of irregularly shaped nuclei and vesicles. Last but not least, we foresee future OT upgrades with respect to overcoming phototoxicity and system drifting for longer duration live-cell measurements; multimodal integration with advanced imaging and nanotechnology to obtain higher spatiotemporal resolution; and developing simultaneous, automated, and artificial intelligence–inspired multi-trap systems to achieve high throughput. These further developments will grant unprecedented accessibility of OT-DFS and force measurement nanotools to a wider biomedical research community, ultimately opening the floodgates for exciting live-cell mechanobiology and novel therapeutic discoveries.

Thoracic endovascular aortic repair (TEVAR) is a common treatment for Stanford type B aortic dissection (TBAD). However, re-entry tears might be found distal to the stented region which transports blood between the true and false lumens. Sealing the re-entry tears, especially for the thoracic tears, could further reduce blood perfusion to the false lumen; however, it might also bring risks by re-intervention or surgery. Wise determination of the necessity to seal the re-entry tears is needed. In this study, patient-specific models of TBAD were reconstructed, and the modified models were established by virtually excluding the thoracic re-entries. Computational hemodynamics was investigated, and the variation of the functional index and first balance position (FBP) of the luminal pressure difference, due to the sealing of the re-entries, was reported. The results showed that the direction of the net flow through the unstented thoracic re-entries varied among cases. Excluding the re-entries with the net flow toward the false lumen may induce the FBP moving distally and the relative particle residence time increasing in the false lumen. This study preliminarily demonstrated that the hemodynamic status of the re-entry tears might serve as an indicator to the necessity of sealing. By quantifying the through-tear flow exchange and shift of FBP, one can predict the hemodynamic benefit by sealing the thoracic re-entries and thus wisely determine the necessity of further interventional management.

Although microorganisms and silicon are well documented as factors that mitigate salt stress, their effect mitigating saline-alkaline stress in plants remains unknown. In this study, wheat plant seeds were treated with silicon, Enterobacter sp. FN0603 alone and in combination of both. Wheat seeds were soaked in silicon and bacterial solutions and sown in pots containing artificial saline-alkaline soils to compare the effects among all treatments. The results showed that the treatments with silicon and FN0603 alone significantly changed plant morphology, enhanced the rhizosphere soil nutrient content and enzyme activities, improved some important antioxidant enzyme activities (e.g., superoxide dismutase) and the contents of small molecules (e.g., proline) that affected osmotic conditions in the top second leaves. However, treatment with silicon and FN0603 in combination significantly further increased these stress tolerance indexes and eventually promoted the plant growth dramatically compared to the treatments with silicon or FN0603 alone (p < 0.01), indicating a synergic plant growth-promoting effect. High relative abundance of strain FN0603 was detected in the treated plants roots, and silicon further improved the colonization of FN0603 in stressed wheat roots. Strain FN0603 particularly when present in combination with silicon changed the root endophytic bacterial and fungal communities rather than the rhizosphere communities. Bipartite network analysis, variation partitioning analysis and structure equation model further showed that strain FN0603 indirectly shaped root endophytic bacterial and fungal communities and improved plant physiology, rhizosphere soil properties and plant growth through significantly and positively directing FN0603-specific biomarkers (p < 0.05). This synergetic effect of silicon and plant growth-promoting microorganism in the mitigation of saline-alkaline stress in plants via shaping root endophyte community may provide a promising approach for sustainable agriculture in saline-alkaline soils.

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