A " performance-inheritance" strategy for achieving hydrophilic/ hydrophobic fluorescent biomass-derived carbon dots through simple solvothermal treatments

It remains a challenge to obtain hydrophilic/hydrophobic materials with promising biocompatibility and environmental compatibility by simple methods. Herein, we designed a "performance-inheritance" strategy and for the first time constructed hydrophilic/hydrophobic fluorescent spirulina-derived carbon dots (CDs) through simple solvothermal treatments. The contact angle of hydrophobic CDs with near-infrared (NIR) fluorescence is 110 degrees, while hydrophilic CDs with blue fluorescence is 19 degrees We further revealed that the NIR luminescence is derived from the chlorophyll structure, while blue fluorescence is from the surface states. Based on the hydrophilicity/hydrophobicity of CDs, a ratiometric sensor was constructed to detect water content in organic solutions. In addition, CDs with NIR emission have low toxicity and good biocompatibility, making them efficient probes for bioimaging. This strategy provides a simple method for the high value-added conversion of algae and a new perspective for the "design-preparation-application" of biomass-derived CDs with specific properties.