Since the number of raw material selections for the synthesis of carbon dots (CDs) has grown extensively, herbal medicine as a precursor receives an increasing amount of attention. Compared with other biomass precursors, CDs derived from herbal medicine (HM-CDs) have become the most recent incomer in the family of CDs. In recent ten years, a great many studies have revealed that HM-CDs tend to be good at theranostics without drug loading. However, the relevant development and research results are not systematically reviewed. Herein, the origin and history of HM-CDs are outlined, especially their functional performances in medical diagnosis and treatment. Besides, we sort out the herbal medicine precursors, and analyze the primary synthetic methods and the key characteristics. In terms of the applications of HM-CDs, medical therapeutics, ion and molecular detection, bioimaging, as well as pH sensing are summarized. Finally, we discuss the crucial challenges and future prospects.
Background
Despite novel advances in screening, targeting and immunotherapies, early diagnosis and satisfactory treatments against hepatocellular carcinoma (HCC) remain formidable challenges. Given the unique advantages, carbon quantum dots (CQDs) become a smart theranostic nanomaterial for cancer diagnosis and therapy.
Results
In this work, a type of bio-friendly CQDs, trichrome-tryptophan-sorbitol CQDs (TC-WS-CQDs), is synthesized from natural biocompatible tryptophan via the one-pot hydrothermal method. Compared with normal hepatocytes, a much stronger green fluorescence is detected in HCC cells, indicating the ability of TC-WS-CQDs to target HCC cells. Furthermore, green-emitting TC-WS-CQDs generate large amounts of reactive oxygen species (ROS), leading to autophagy of HCC cells. Additionally, the green-emitting TC-WS-CQDs perform significant tumor inhibition by inducing autophagy via p53-AMPK pathway in vitro and in vivo studies with almost no systemic toxicity.
Conclusions
The results may highlight a promising anticancer nanotheranostic strategy with integration of diagnosis, targeting, and therapy.
Graphical Abstract
A CO2 sensor made of nano crystalline CuO–BaTiO3 semiconductor, which has a giant capacitance effect, is designed based on the principle of the physical effect in the nano cluster. After an experimental investigation of its microstructure, the correlation between the quantum size effect and the giant capacitance effect is suggested. The characteristic physical quantities relating to the giant capacitance effect of the sensor are studied systematically with the aid of a gas detector. The quantum size effect is introduced as an interpretation for the mechanism of the giant capacitance effect and a model is proposed for describing the giant capacitance effect of the sensor.
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