Fluorescent fiber is a kind of fiber that can absorb visible or ultraviolet light source, and then convert these light source into light radiation or return to the original color after irradiation. Due to its photosensitivity, fluorescent fiber has a broad application prospect in luminescent textiles, bioengineering and medical products, and is one of the hotspots of advanced materials research.

Natural silk has excellent biocompatibility and mechanical properties, is a kind of widely used fiber material, but under ultraviolet light, silk is light blue, light yellow or no fluorescence effect. Gene modification technology and organic dye dyeing technology are common ways to prepare fluorescent silk, but their high cost, poor safety and environmental protection problems are also very obvious. Therefore, feeding silkworms with non-toxic, biocompatible, environmentally friendly, high luminescence and low cost materials seems to be one of the best ways to produce fluorescent silk.

Recently, Fudan University reported that a kind of carbon spot (CDs) prepared from mulberry leaves has strong near infrared fluorescence, with an absolute quantum yield (QY) of 73% and a half-peak full width (FWHM) of 20 nm. It is the brightest dark red emission carbon spot (R-CDS) known so far, and has good biocompatibility and fluorescence stability.

Silkworms, fed with CDs, fluoresce bright red and are able to grow healthily and form cocoons normally, which are pink in sunlight and bright red fluoresce in ultraviolet light. The metabolic pathway of CDs can be obtained through the anatomical analysis of experimental silkworm and cocoon, that is, fluorescent CDs is absorbed by silkworm from digestive tract, then transferred to silk gland, and finally into cocoon, and the unabsorbed CDs is excreted with feces.

This study is the first time that near-infrared emission CDs has been used to safely feed silkworms to produce fluorescent silk. Because r-cds can be easily prepared from mulberry leaves on a large scale, and the survival rate of feeding silkworm is close to 100%, it can be used for the large-scale preparation of fluorescent silk and expand its practical application field in the future.

Mulberry Leaves Derived Red Emissive Carbon Dots for Feeding Silkworms toProduce Brightly Fluorescent Mulberry Leaves Derived Red Emissive Carbon Dots for Feeding Silkworms toProduce Brightly Fluorescent Mulberry "Silk" was published in Advanced Materials.