Longjian Xue

This review highlights recent advances in bioinspired structured adhesives, elucidating how setae, suckers, and smooth pads enable reversible adhesion, and discusses opportunities and challenges for future development.

Freshwater shortages have attracted increasing global concern. Solar-driven evaporation from wastewater or seawater has emerged as a promising technology to collect fresh water; however, achieving high-evaporation efficiency remains a significant challenge. Here, we propose a capillary-regulated solar evaporator, CHALS, derived from agricultural waste—specifically, lotus stems. CHALS is constructed by the carbonization and hydrophilization of a compressed assembly of lotus stems. The compression, followed by carbonization, narrows the straight capillary channels; subsequent oxygen plasma treatment optimizes surface hydrophilicity. The two synergistic effects jointly elevate the Laplace capillary driving force to greatly accelerate internal water transportation. Meanwhile, the straight-through channels provide the shortest pathway for water transportation. Moreover, the efficient photothermal conversion raises the surface temperature of CHALS up to 65 °C. Benefiting from these synergistic effects, CHALS achieves an evaporation rate of 2.60 kg·m⁻²·h⁻¹ under 1 sun irradiation. The work not only provides an agricultural waste-derived solar evaporator but also establishes a capillary-regulation strategy to boost solar evaporation efficiency.

The clinical need for maxillofacial reconstruction requires a deeper understanding of site-specific skeletal stem cell biology. The periosteum serves as a critical reservoir of adult skeletal stem progenitor cells (SSPCs) that navigate microscale stiffness gradients during bone healing. However, whether periosteal SSPCs from distinct skeletal sites exhibit divergent mechanosensitive responses remains poorly understood. This study compared the phenotypic characteristics and mechanotactic behaviors of mouse periosteal SSPCs (passage 3) from mandible (m-pSSPCs) and long bone (l-pSSPCs). Furthermore, we evaluated cell migration and adhesion using our previously reported flat PDMS substrate with periodic subsurface stiffness patterns (20-µm or 50-µm periods; stiffness differentials of ~0.3 MPa and ~0.5 MPa, respectively). While both cell types exhibited similar basal morphologies, flowcytometry and western blot analysis revealed a significantly higher proportion of osteogenic progenitors in m-pSSPCs compared to l-pSSPCs. Notably, m-pSSPCs displayed scale-dependent directional migration, morphological elongation and alignment exclusively on 50-µm patterns, whereas l-pSSPCs remained unresponsive across all scales. Transcriptomic profiling identified a marked enrichment of calcium-channel genes in m-pSSPCs, with Trpv2 significantly upregulated. Selective Trpv2 silencing abolished the characteristic polarization and alignment of m-pSSPCs on 50-μm stiffness patterns. Our findings demonstrate that m-pSSPCs possess a unique, Trpv2-dependent sensitivity to microscale mechanical cues, revealing site-specific mechanosensing programs in skeletal progenitors. These results highlight the necessity of considering tissue-specific cellular programs when designing “instructive” biomaterials for craniofacial regeneration.

Biomimetics seeks to translate principles from living systems into innovative engineering solutions by drawing on the remarkable efficiency, adaptability, and multifunctionality found in nature

Understanding how cells respond to mechanical signals is crucial for elucidating the mechanisms involved in tissue development and disease progression. However, existing in vitro cell culture substrates often fail to replicate the physiological stiffness gradients at the cellular scale while also eliminating confounding topographical cues. In this study, we present a decoupled stiffness model utilizing a bilayer polydimethylsiloxane (PDMS) substrate. This substrate consists of a soft, flat top film suspended over a rigid underlayer featuring ridge-and-groove microstructures. The top layer effectively transmits stiffness variations in the underlying structure while maintaining uniform topography and chemistry at the cell contact surface. Stiffness modulation is achieved by varying the width of the alternating ridges and grooves, which are spaced equally. Scanning electron microscopy confirmed the flat surface morphology and consistent contact topography. Atomic force microscopy demonstrated that stiffness variations were dependent on the microstructure: for 20 μm patterns, the elastic moduli were approximately 950 kPa for ridges and 850 kPa for grooves; for 50 μm patterns, these values were around 1070 kPa and 950 kPa, respectively. Mouse primary bone marrow cells adhered well and spread on the substrate, showing a preference for nuclear localization toward the stiffer ridge regions in the 50 µm pattern (61.49%, p < 0.05), thereby confirming effective cellular perception of the mechanical gradient. In summary, this protocol offers a reproducible method to construct a cell culture substrate with microscale stiffness gradients, minimizing the chemical or topography interference, enabling investigations into cell mechanotransduction.

Understanding how cells respond to mechanical signals is crucial for elucidating the mechanisms involved in tissue development and disease progression. However, existing in vitro cell culture substrates often fail to replicate the physiological stiffness gradients at the cellular scale while also eliminating confounding topographical cues. In this study, we present a decoupled stiffness model utilizing a bilayer polydimethylsiloxane (PDMS) substrate. This substrate consists of a soft, flat top film suspended over a rigid underlayer featuring ridge-and-groove microstructures. The top layer effectively transmits stiffness variations in the underlying structure while maintaining uniform topography and chemistry at the cell contact surface. Stiffness modulation is achieved by varying the width of the alternating ridges and grooves, which are spaced equally. Scanning electron microscopy confirmed the flat surface morphology and consistent contact topography. Atomic force microscopy demonstrated that stiffness variations were dependent on the microstructure: for 20 μm patterns, the elastic moduli were approximately 950 kPa for ridges and 850 kPa for grooves; for 50 μm patterns, these values were around 1070 kPa and 950 kPa, respectively. Mouse primary bone marrow cells adhered well and spread on the substrate, showing a preference for nuclear localization toward the stiffer ridge regions in the 50 µm pattern (61.49%, p < 0.05), thereby confirming effective cellular perception of the mechanical gradient. In summary, this protocol offers a reproducible method to construct a cell culture substrate with microscale stiffness gradients, minimizing the chemical or topography interference, enabling investigations into cell mechanotransduction.

Indwelling catheters are highly needed in medical diagnostics, treatment, and implantations. However, the obstruction arisen from biofilm formation and crystalline encrustation hinders the long‐term indwelling use of catheters. Here, inspired by kelp, a wavy self‐secretion surface (WSS) with robust anti‐encrustation is established by integrating wavy surface of polydimethylsiloxane and self‐secretion of silicone oil. WSS possesses remarkable resistance to biofluids, bacteria, and urinary crystals, achieving an anti‐encrustation efficiency of 96.44% of urine crystals, and showing superior self‐cleaning capability compared to the non‐engineered counterpart. The oil film on WSS significantly reduces direct contact between the urinary contents and the WSS surface, while the wavy structure induces flow turbulence, further enhancing the anti‐adhesion properties. Moreover, the high stability of the oil film, offered by the wavy structure and the polymeric brush, and the sustained self‐secretion ensure the long‐term use of WSS. Therefore, the work here establishes a bioinspired strategy for the surface design of indwelling catheters that can find wide applications in long‐term indwelling medical devices.