<i>Chlorella Vulgaris</i>‐Inspired Versatile Theranostic Nanoparticles for Specific Recognition and Detoxification to Copper (II) In Vitro and In Vivo

Abstract Specific recognition and detoxification for copper is the key step for the early diagnosis and treatment of various diseases such as neurodegenerative disease and Wilson's disease. Herein, a Chlorella vulgaris ‐inspired versatile theranostic nanoparticles is facilely and greenly prepared by assembling quercetin into poly(beta‐cyclodextrin) (PQNPs), which is further employed in the specific recognition and detoxification for Cu 2+ in vitro and in vivo. PQNPs can be used in the detection of Cu 2+ in aqueous solutions with fast response time (&lt;5 s) and low detection limit (6.499 n M ). The detection for Cu 2+ in water and serum can be achieved by naked eye instantaneously on a PQNPs‐based paper sensor, and PQNPs can also act as a biological diagnostic agent for the Cu 2+ imaging. Remarkably, PQNPs significantly enhance cell viability of the cell models induced by Cu 2+ through the synergistic capacities of chelating Cu 2+ and antioxidation. The detoxification of PQNPs for copper poisoning model is further ascertained in vivo, and it found that poly‐β‐cyclodextrin is capable of crossing the blood–brain barrier. Taken together, the as‐prepared versatile theranostic nanoparticles possess advantages of simple composition, significant theranostic efficacy, and novel treatment pattern, presenting an intriguing avenue to develop therapeutics for tackling abnormal copper metabolism in the clinic.