Tensile force is usually considered a destructive factor, as it can cause bond rupture, but recently this force has been demonstrated to be productive if the compounds are properly designed. Some force-responsive compounds (or mechanophores) with specific structural elements, such as strained rings, weak bonds or isomerizable bonds, are force activable to change color, emit light, release small molecules, or trigger new reactions if the appropriate force is applied. We are interested in exploring the effect of force to chemical reactions from the physical perspective. Using single molecule force spectroscopy as the major tool, we discover unconventional mechanophors that are sensitive to force directions and amplitudes and study their force-dependent transitions.

Huang Wenmao et al. Nature Chemistry 2019

   It is increasingly clear that extracellular matrix (ECM) not only provide a mechanical support but also important mechanical cues that regulate fundamental cellular functions. The structure and mechanical properties of ECM can change dramatically in health tissues during development, homeostasis and aging as well as in pathological tissues, including fibrosis and cancer. Currently, we are devoted in combining single molecule mechanical characterization and hydrogel engineering to understand the effect of forces exerted by residing cells on the remodeling of synthetic ECM network. We are also interested in exploring the effect of ECM structures and mechanical properties on cell migration, stem cell differentiation and cardiomyocyte beating synchronization.

    In nature, different tissues have evolved to possess unique mechanical features for diverse biological functions. For example, articular cartilage is strong (strength of 9–40 MPa), tough (fracture energy of 1,000–15,000 Jm⁻²) and elastic (failure strain of 60–120%); ascending aorta is soft (strength of 0.3–0.8 MPa), whereas mammalian tendon is strong (strength of 50–100 MPa) and resilient (resilience of ~90%) but relatively inextensible (failure strain of 12–16%). A key challenge in biomaterials research is to produce synthetic hydrogels that can replicate the diverse mechanical properties of the naturally occurring tissues for various biomedical applications. We are trying to engineer hydrogels that can be specifically tailored with desired mechanical properties using recombinant proteins and synthetic peptides as the major building blocks. Currently we are working on hydrogels with extreme mechanical properties and hydrogels with dynamic mechanical responses.

Wu Junhua et al. Nature Communications 2018

   Synthetic adhesives are difficult to be used in wet environments due to the hydration of surfaces and high salt conditions, yet marine mussels can firmly affix on wet rock surfaces by overproduction of various adhesive proteins containing a rare catecholic amino acid, Dopa. We are trying to understand the fundamental physics and mechanics underlying the wet adhesion of naturally occurring adhesive proteins secreted by various marine species. We are also interested in engineering antifouling surfaces to combat the marine biofouling problems.

Li Yiran et al. ACS Biomaterials Science & Engineering 2017