Bioinspired quantum dots: advancing diagnostic and therapeutic strategies in breast cancer

Abstract

Bioinspired quantum dots (BQDs) have garnered significant attention in recent years because of their unique characteristics, including their nanoscale size (less than 10 nm), high surface area, photoluminescence, chemical stability, and ease of synthesis and functionalization. Researchers are increasingly shifting towards the use of biomass-derived precursors instead of chemical compounds for BQD fabrication. These biomass sources are sustainable, eco-friendly, cost effective, widely available, and enable the conversion of waste into valuable materials. In this review, we provide a comprehensive analysis of various fabrication methodologies for BQDs, and the diverse raw materials used in recent studies. Owing to their exceptional properties, combined with simple synthesis routes, BQDs are promising candidates for a range of biomedical applications, particularly in bioimaging, targeted drug delivery, and phototherapy for cancer treatment. BQDs exhibit excellent aqueous solubility, low toxicity, biocompatibility, facile biofunctionalization, and selective cancer targeting. Furthermore, their photoluminescent properties, high longitudinal relaxation values, photothermal effects upon laser irradiation, ability to generate singlet oxygen, and production of H₂S for gas therapy make them highly effective as cancer theranostic agents. This review specifically highlights the potential of BQDs in breast cancer management while addressing existing challenges in their application.

Fig. 1. Schematic illustration representing synthesis and biomedical uses of bioinspired quantum dots.

Fig. 2. Diagrammatic representation of the experimental stages involved in the green synthesis of CdS quantum dots (QDs) using Camellia sinensis extract and its biomedical applications.

Fig. 3. Schematic illustration of the preparation of CQDs from Aloe vera leaf extract. Source: reproduced with permission from Malavika et al. (2021).

Fig. 4. Schematic illustration of HBCDs derived from hypocrella bambusae for bimodel FL/PA imaging and synergistic PDT/PTT of cancer (Source: reproduced with permission from Jia et al., 2018).

Fig. 5. Control of the doping concentration of S-GQDs. Doping concentration of S-GQDs obtained at different (a) reaction temperatures and (b) reaction times. (c) PL spectra of S-GQDs with different doping concentrations. Inst: photographs of S-GQDs with different doping concentrations under 365 nm UV light. (d and e) Relationships between the doping concentration and (d) λ_ex, (e) the excitation wavelength-dependent behavior and (f) the quantum yield of S-GQDs. (g–k) Confocal fluorescence microphotograph of fibroblasts (scale bar: 20 μm) incubated with S-GQDs, (g) S-GQDs-1, (h) S-GQDs-3, (i) S-GQDs-5, (j) S-GQDs-7 and (k) S-GQDs-9. (Source: reproduced with permission from Wang et al., 2018).

Fig. 6. Illustration of the antibacterial mechanism of action of Ag@CDs via adsorption and subsequent penetration of Ag@CDs into the bacterial cell leading to cell wall deformation, protein denaturation, ROS generation, genomic DNA disruption, phospholipids release, and cytoplasmic leakage. (Source: reproduced with permission from Omran et al., 2021).

Fig. 7. Surface functionalization approaches for bioinspired quantum dots.

Fig. 8. Typical molecular structures of amphiphilic copolymers for membrane applications (Source: reproduced with permission from Yi et al., 2024).

Fig. 9. (I) Morphology of the fruit parts of Enterolobium contortisiliquum. (A): entire fruit and (B): cotyledons and a seed indicated by the red arrow. (II) Morphology of the fruit parts of Enterolobium contortisiliquum. (A): entire fruit and (B): cotyledons and a seed indicated by the red arrow. (Source: reproduced with permission from Santos et al., 2023).

Fig. 10. Diagrammatic representation of the applications of bioinspired QDs in breast cancer theranostics.

Fig. 11. (a) In vivo FL imaging of mice post-i.v. injection of HBCDs in PBS. (b) FL intensities of tumors in (a). (c) Ex vivo FL imaging of tumor and major organs at different time points post-i.v. injection of HBCDs in PBS. (d) FL intensities of major organs and tumor in (c). (e) In vivo PA imaging of mice post-i.v. injection of HBCDs in PBS. (f) PA intensities of tumors in (e). Data are expressed as means ± s.d. (n = 3). (Source: reproduced with permission from Jia et al., 2018).

Fig. 12. CLSM images at two laser excitation wavelengths: 488 nm (green) and 550 nm (red) using GQDs@Cys-BHC complex (final concentration; ∼200 μg mL⁻¹ GQD concentration in the complex). Images show HeLa cells (a–d), L929 cells (e–h), and MDA-MB-231 cells (i–l) stained with GQDs@Cys-BHC complex. Cellular intake is clearly demonstrated by co-localization merged channels (Source: reproduced with permission from Thakur et al., 2016).

Fig. 13. Diagrammatic illustration of graphene quantum dot (GQD) synthesis from pasteurized cow milk, functionalization with Cys-HCl, drug loading with BHCs, and application in cellular bioimaging.

Fig. 14. (a) IR thermal images of mice post different treatments. (b) Temperature curves of tumor during the irradiation. (c) Photographs of mice post different treatments. (d) The growth curves of tumor during different treatments. (e) H&E-stained slices of tumor post different treatments. Data are expressed as means ± s.d. (n = 5). (Source: reproduced with permission from Jia et al., 2018).