# Hybrid Quantum Dot as Promising Tools for Theranostic Application in Cancer
## 3 Hybrid Quantum Dot as Cancer Theranostics: Contemporary Research
### Therapeutic Application
developed a hybrid nanostructure of cetyl alcohol-modified graphene quantum dots (CA-GQDs) and conjugated them with iron-oxide nanoparticles (IONP@CA-GQD) [44]. The study indicated no effect on the normal architecture of the liver and cardiac tissues after administration of these hybrid QDs at a dose of 3 mg/kg for 7 days in mice. Hence, IONP@CA-GQD can be offered as a potential drug delivery system for cancer theranostics. Moreover, IONP@CA-GQD was found to be more toxic for the tumor cells as compared to normal cells in the study [39; 83]. It is due to the hydrophobic nature of the carbon chains of cetyl alcohol and oleic acid in the middle of IONP@CA-GQD, hydrophobic drugs can be loaded in this space [83; 104]. Furthermore, the magnetic properties of IONP@CA-GQD would make cancer targeting feasible through this theranostic system. Similarly, [PERSON] et al. examined QD-labeled hyaluronic acid (HA) derivatives for liver-targeted intracellular drug delivery. EDC activation of HA's carboxyl group and conjugation to ADH's amine group produced HA-ADH conjugates. After EDC and sufo-NHS activation of QD carboxyl groups, HA-ADH conjugates were tagged with QDs via amide bond formation. HA binds CD44 via its three carboxyl groups [88]. HA-QD conjugates were endocytosed via HA receptor-mediated endocytosis, as seen in the confocal microscopic images of B16F1 cells. HA receptors such as CD44 are significantly expressed in B16F1 cells. In the case of HEK293 cells without HA receptors, the cellular uptake of HA conjugates and QDs conjugates was noticeably reduced (as shown in Figure 4). Figure 4: Illustration shows the cellular uptake of hyaluronic acid (HA) conjugated hybrid QDs after 2 h incubation in B16F1 cells—a high expression of HA receptors (**A**); HEK293 cells—without HA receptors (**B**). Confocal microscopic images reveal low cellular uptake of developed hybrid QDs system in HEK293 cells. Reproduced from [PERSON] et al. [88], Elsevier, 2012. In order to deliver targeted anticancer drugs, [PERSON] et al. created a core-shell structured multifunctional nanocarrier system (ZnO-Au-PLA-GPPS-FA) consisting of ZnO-quantum dots-conjugated AuNPs as the core and folic acid (FA)-conjugated amphiphilic hyperbranched block copolymers as the shell. ZnO-quantum dots-conjugated AuNPs could be employed for photothermal therapy to kill tumor cells and fluorescent labeling, respectively. The outer hydrophilic block (GPPS-FA) and the inner hydrophobic block (PLA) were both biocompatible and biodegradable in in vivo system. The cancer cells may be targeted by an FA-conjugated multifunctional nanocarrier system, which may then be absorbed by the target cell through receptor-mediated endocytosis. Additionally, the presence of GPPS on the surface of multifunctional nanocarrier systems resulted in some of their anticancer effects [105]. In another investigation, [PERSON] et al. made a targeted RBC-membrane-encased nanosponge (RBC-NS) that combines stealth and huge payloads of functional molecules to avoid the low EPR effect and the different types of tumors. This biocompatible, light-sensitive, carbon-based, porous particle looks like red blood cells (RBCs) and targets and gets into tumors well [39]. The targeted nanosponge, made of protein/RBC membranes (targeting and stealth properties), porous carbon/silica (hydrophobic, therapeutic agent transport), and graphene QDs (GQDs)/drug (photorespusive, tumor-penetrating), were injected into a mouse model to deliver docetaxel (DTX) and GQDs to tumors (Figure 5). Moreover, Cetuximab (Ct), which can target tumors, is attached to the RBC layer to make it easier for particles to gather around tumors. The nanosponge delivers high amounts of GQD/DTX to the tumor as a photo-penetrative and photolytic agent. The Ct-RBC-GQD/NS-treated tumor can be heated to 68 \({}^{\circ}\)C for thermal tumor ablation. Ct-RBC-NS and Ct-NS elevated tumor temperatures to 62 and 53 \({}^{\circ}\)C, respectively. Irradiated saline-treated mice showed no temperature increase.