Quantum dot-based conjugates: Luminous nanotools for cancer research

Nanotechnology has opened a new era in life science research, offering innovative nanotools to understand complex biological processes, such as those associated with cancer. Among the nanosystems, quantum dots (QDs) stand out for their remarkable optical properties, which render them valuable fluorescent nanoprobes in biological investigations. Moreover, their chemically active surfaces allow conjugations with (bio)molecules, other nanoparticles (NPs), and electrodes, enabling their use in multimodal site-specific applications and biosensing. The complexity and heterogeneity of cancer present challenges for its early diagnosis and personalized treatments. The conjugation of QDs with biologically relevant molecules can provide versatile nanotools for untangling cell mechanisms and biomarker patterns, thereby advancing the knowledge of cancer biology. This review illustrates the multifaceted capabilities of QDs, particularly in cancer research, drawing from applications at cell and tissue levels involving their conjugation with (i) low molecular weight molecules (e.g., folic acid, boronic acid, and glucose analog), (ii) macromolecules (e.g., holo-transferrin, lectins, and protease inhibitor), and (iii) optical-magnetic nanosystems combining QDs with superparamagnetic iron oxide NPs and holo-transferrin. The review also brings an overview of the fundamentals of QDs and strategies for their conjugation. By synthesizing findings from a range of studies, we hope that this review inspires new applications of QD-based conjugates in cancer biology, gathering knowledge and contributing to developing enhanced diagnostic and therapeutic procedures for this disease.