# Hybrid Quantum Dot as Promising Tools for Theranostic Application in Cancer
## 3 Hybrid Quantum Dot as Cancer Theranostics: Contemporary Research  
### Diagnostic Application  
[PERSON] et al. developed fluorescent hyper-cross-linked-cyclodextrin-carbon quantum dot (CD-CQD) hybrid nanosponges with outstanding biocompatibility and intense bright blue fluorescence excited at 365 nm with a PLQY of 38.0% [82]. These hybrid QDs systems were generated by simple condensation polymerization of carbon quantum dots (CQDs) with cyclodextrin (CD) at a 1:5 feeding ratio for theranostic applications, specifically in malignancies. In another investigation, [PERSON] et al. made a hybrid nanostructure of  
Figure 3: Schematic illustration highlights the accumulation and removal of QDs versus hybrid QDs. QDs are more prone to RES clearance and renal clearance compared to hybrid QDs of a stealth nature. The more targeted delivery of hybrid QDs compared to QDs resulted in major accumulation in tumor tissues due to receptor-mediated endocytosis and the EPR effect, leading to improved therapeutic outcomes. “Image created with BioRender.com”. graphene quantum dots (GQDs) and magnetic nanoparticles (MNP) by using hydrophobic interactions between long carbon chains on the surface of GQDs around the edges and MNP in the middle [83]. Pyrolysis was used to create GQDs, which were then changed using cetyl alcohol (CA) to produce surfactant-modified GQDs (CA-GQDs). Moreover, an oleate-iron complex has been utilized to make iron-oxide nanoparticles (IONP) as MNP. After that, CA-GQDs and IONP are mixed to make a structure with IONP in the middle and CA-GQDs all around it (IONP@CA-GQD). IONP@CA-GQD possesses both fluorescence and magnetic characteristics. At room temperature, IONP and IONP@CA-GQD have been tested for magnetization hysteresis loops in a moving magnetic field. There have been no observations of coercivity or remanence, indicating super-paramagnetism. The computed MS values for IONP and IONP@CA-GQD are 34.1 emu/g and 37.8 emu/g, respectively. Because of GQDs are fluorescent in nature, this hybrid structure could also be used for bioimaging [84; 85]. A stable compound of graphene oxide (GO) and graphene quantum dots (GQD) was created by [PERSON] et al. by electrostatic layer-by-layer assembly using a polyethylene imine bridge (GO-PEI-GQDs) [86]. In addition, various applications of the mono-equivalents of the GO-PEI-GQDs complex were compared, including cell imaging (diagnostics), photothermal, and oxidative stress responses in MDA-MB-231 breast cancer cells. When exposed to an 808 nm laser for 5 min at a concentration of up to 50 \(\upmu\)g/mL, GO-PEI-GQDs displayed an outstanding photothermal response (44-49 \({}^{\circ}\)C). According to the study, GO-PEI-GQDs had synergistic effects on cancer cells. It has stable fluorescence imaging, improved photothermal effects, and cytotoxic actions. Composite materials made of GO and GQDs combine many different properties, which makes it possible to improve certain therapeutic systems, such as cancer theranostics [86]. Hyaluronic acid and QDs together have been proven to be useful tools for improving intracellular transport into liver cells. This is accomplished by interacting with CD44-receptors, which allows for in vivo real-time imaging [87; 88]. The anionic polysaccharide chondroilitate was employed to coat the positively charged oily core of the cadmium telluride (CdTe) QDs as cancer theranostic nanocapsules [89], which were also loaded with rapamycin and elecoxib as anticancer therapeutics [90]. Chondroitin sulfate nanocapsules have an exterior coating of cationic gelatin-coupled QDs placed on them to prevent non-specific uptake by healthy cells. Matrix metalloproteinase (MMPs) dissolved the gelatin at the tumor location, releasing therapeutic nanocapsules and QDs into cancer cells for therapeutic and imaging action as a cancer therapeutics. An ON-OFF effect, where the fluorescence of QDs was first quenched by energy transfer and then restored after bond cleavage in tumor cells, was seen in a study that substituted lactoferrin for gelatin [90].