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Abstract Synthetic opioids, especially fentanyl and its analogs, have created an epidemic of abuse and significantly increased overdose deaths in the United States. Current detection methods have drawbacks in their sensitivity, scalability, and portability that limit field‐based application to promote public health and safety. The need to detect trace amounts of fentanyl in complex mixtures with other drugs or interferents, and the continued emergence of new fentanyl analogs, further complicates detection. Accordingly, there is an urgent need to develop convenient, rapid, and reliable sensors for fentanyl detection. In this study, a sensor is prepared based on competitive displacement of a fluorescent dye from the cavity of a supramolecular macrocycle, with subsequent fluorescence quenching from graphene quantum dots. This approach can detect and quantify small quantities of fentanyl along with 58 fentanyl analogs, including highly potent variants like carfentanil that are of increasing concern. Detection of these agents is possible even at 0.01 mol% in the presence of common interferents. This simple, rapid, reliable, sensitive, and cost‐effective approach couples supramolecular capture with graphene quantum dot nanomaterial quenchers to create a tool with the potential to advance public health and safety in the context of field‐based detection of drugs in the fentanyl class. 

Abstract Photothermal reagents sensitive to near‐infrared (NIR) light are promising imaging agents and therapeutics for anticancer applications because of the deep tissue penetration of NIR light, allowing for spatiotemporal control over the therapeutic activity, with minimal damage to normal tissues. Herein, a new class of NIR‐sensitive biopolymer‐based nanoparticles is presented by covalently conjugating indocyanine green (ICG) onto the surface of naturally occurring glycogen nanoparticles. The resulting ICG‐glycogen conjugates exhibit a markedly enhanced aqueous stability in comparison to free ICG molecules. Furthermore, an efficient light‐to‐heat conversion is enabled by ICG‐glycogen conjugates, as evidenced by the elevated temperatures of their aqueous solutions upon exposure to NIR light. Critically, ICG‐glycogen conjugates are capable of cell internalization, and under NIR irradiation the effective eradication of breast cancer cells, demonstrating their potential in photothermal therapy for cancer.