Self-assembly method for the preparation of near-infrared fluorescent spider silk coated with CdTe nanocrystals

Spider silks have great potential in many fields due to their high strength and superb toughness. In this work, fluorescent spider silks were fabricated by consecutively assembling CdTe nanocrystals and polyelectrolyte (PE) macromolecules onto spider dragline silks. Scanning electron microscopy and fluorescence microscopy images showed that a large number of CdTe nanocrystals and PE molecules were successfully deposited on the surface of the spider silks, and the silk composites obtained exhibited core-shell structure characteristics. The energy dispersion x-ray spectrum (EDS) showed that the silk composites contained about 2.68% (w/w) of CdTe nanocrystals when the spider silks were coated with just one layer of PE/CdTe/PE. The resulting fluorescent spider silks exhibited very bright fluorescence, and their emission spectrum was located in the near-infrared (NIR) band. The mechanical properties of these modified spider silks, such as the maximum pull force and the elastic limit elongation when a single spider silk strand breaks, showed a slight decrease after coating with CdTe nanocrystals and PE. This fluorescent spider silk is envisioned to have applications in materials science, microelectronics, and even biology.