Cactus-Inspired Photonic Crystal Chip for Attomolar Fluorescence Multi-analysis.

Automation and efficiency requirements of environmental monitoring are the pursuit of spontaneous sampling and ultrasensitivity for current sensory systems or detection apparatuses. In this work, inspired by cactus hierarchical structures, we develop a cactus-inspired photonic crystal chip to integrate spontaneous droplet sampling and fluorescence enhancement for sensitive multi-analyte detection. A conical hydrophilic pattern on hydrophobic surfaces can give rise to unidirectional Laplace pressure, which drives droplet transport to the assigned photonic crystal site. The nanostructure of photonic crystals has bigger capillarity to drive the droplet wetting uniformly into the photonic crystal matrix while performing prominent fluorescence enhancement by their photonic bandgap. A low to attomolar (2.24 × 10-19 M) fluorescence limit of detection (LOD) sensitivity can be achieved by the synergy of spontaneous droplet sampling and fluorescence enhancement. Focused on eutrophic water problems and algae pollution monitoring, a femtomolar (1.83 × 10-15 M) LOD and identification of various microcystins in urban environmental water can be achieved. The suitable integration of the unidirectional droplet transport by Laplace pressure and fluorescence enhancement by photonic crystals can achieve the spontaneous sampling and signal enhancement for ultratrace detections and sample survey of environmental monitoring and disease diagnosis.

Silkworm spinning inspired 3D printing toward a high strength scaffold for bone regeneration.

Inspired by the silkworm spinning process for production of tough cocoons, a gradient printing-assembly technique with silk fibroin (SF) and hydroxyapatite (HA) to achieve high strength scaffolds for bone regeneration is developed. A coaxial extrude-nozzle is employed to provide gathered thickening and shearing for aligned assembly. The aligned SF-HA assembles into the compacted nanostructure, which performs a maximum compressive strength of 166 MPa and bending strength of 40 MPa. Scaffolds with various morphologies could be arbitrarily constructed via extruded 3D printing for the regeneration of cortical bone or cancellous bone. The hemolysis quantification of red blood cells (RBCs), proliferation and flow cytometry of bone marrow stem cells (BMSCs) have proved the excellent biocompatibility of the printed scaffolds. Osteogenic induced differentiation assay in vitro and surgical intervention for rat femoral defect repairing have verified the successful osteogenesis with high mechanical strength and remarkable stability in the physiological environment. The silkworm spinning inspired 3D printing offers a facile approach for the fabrication of implantable scaffolds with high strength and excellent biocompatibility, which is highly desired for the applications of bone tissue engineering.