The leaves of Ginkgo biloba have been proven to have anti-thrombotic effect and can lower blood sugar together with lipid levels [1]. One of the main active components in Ginkgo biloba leaves is well-known flavonoids. Currently, the extraction of flavonoids from Ginkgo biloba leaves primarily involves the use of volatile organic solvents (VOCs) [2]. However, their extraction efficiency is relatively low, which also result in long operation time, worse selectivity, waste of materials and environment-health-safety (EHS) drawbacks. Therefore, finding a more convenient and environmentally sustainable system is of great research importance. At the same time, with the rapid development of China's great health industry, the megatons of ginkgo leaves residue after extraction have not been fully utilized. The current main strategy is to use these waste to produce organic fertilizers to improve soil fertility; or it can be mixed with other feeds to supply the livestock industry. Whether it can be converted into high value-added products and reused in the production process of bioactive ingredients in Ginkgo biloba is a topic worth exploring.

In recent years, ionic liquids (ILs) have greatly promoted the development of natural product extraction with their advantages over traditional solvents, and many flavonoid components have been successfully extracted by various methods using common ILs as solvents [3]. Micelles can be formed by both ionic and non-ionic surfactants (such as the Triton series of surfactants), with ILs forming micelles belonging to the category of ionic surfactants [4]. The presence of micelles in the solution not only increases the solubility of target components but also provides some protection for certain instable substances [5,6]. 0.148 mol/L [EPy]BF4 was screened as the optimal solvent in the ultrasonic (280 W) extraction for biflavonoids from Ginkgo biloba L. in 25 min, and the extraction rates ranged from 2.44 mg/g to 13.97 mg/g [7]. Moreover, 0.75 mol/L [Bmim]Glu in the combinational mode of microwave and ultrasound achieved the extraction rate of 41.34 mg/g [8]. Discovered by quantum chemical and COnductor like Screening MOdel for Realistic Solvents (COSMO-RS) calculations, the solubility of flavonoids in pure ILs increases with their H-bonding acceptor basicity and the alkyl chain length of imidazolium cations owing to solute–solvent hydrogen-bond interactions or van der Waals interactions, and introducing ILs into molecular solvents or water has a significantly enhanced solubilization effect for sparingly soluble flavonoid compounds [9]. However, the types of ionic liquids mentioned above are relatively limited, and reports on the special IL micelles in water for the extraction of flavonoids are still relatively rare.

Another key active component in Ginkgo biloba leaves is the terpenoids (ginkgo terpene lactones), mainly including sesquiterpenoids and diterpenoids with health-care functions [10]. Liquid-liquid extraction (using VOCs such as ethyl acetate, butanone, cyclohexanone, diethyl ether, and chlorinated hydrocarbons) is often applied to obtain them from crude extract [11]. In current reports, the methods for simultaneously obtaining flavonoids and terpenoids from Ginkgo biloba include column chromatography with microporous resins, Sephadex LH-20, poly-amide and silica gel [12,13] or enrichment and purification with resin [14]. Among various hotspot materials, carbon dots (CDs) are carbon-based nanoparticles with nano scale. Compared to macroscopic carbon materials, these microscopic carbon-based materials often possess unique advantages [15]. Their fundamental research and applications have been widely focused on by researchers in the fields of food, chemistry, and materials science. As a key feature, the synthesis of natural CDs utilizes different plant parts [16].

Deep eutectic solvents (DES) are another kind of green solvents, which have also been popularly applied in extraction and separation of natural bioactive compounds [17]. Their current application forms mainly include single solvent, mixed solvent, biphasic system or modifier on solid-phase materials [18], and their combination with CDs as nanofluid lacks investigation. In our preliminary research, it was found that even adding a very small amount of CDs to DES could significantly improve the overall performance of the system. On all above background, the raw material was firstly extracted with IL micelles, and solid residue after extraction was used to prepare NCDs, which were further processed into hydrophobic nanofluid of CDs@DES for further separation of the total extract. As the result, a complete process was established to obtain two important target active products in the following studies. In this study, DES and IL were simultaneously used for capturing various functional constituents as two green solvents, and IL micelles were well explored and showed good performance to obtain flavonoids. Meanwhile, CDs@DES was prepared from extraction residue to separate terpenoids from the extract. The whole biphasic system composed of IL micelles and CDs@DES was friendly, simple, effective and recyclable in the whole applications.