Quantum Dots and their Potential Role in Cancer Theranostics

Abstract

The emergence of cancer nanomedicine is the result of fruitful advances in the fields of nanotechnology, bioimaging, formulation development, and molecular biology. Quantum dots (QDs) are the luminescent nanocrystals (NCs) that provide a multifunctional platform for imaging the biosystems following controlled delivery of therapeutic drugs, proteins, peptides, oligonucleotides, and genes. These engineered fluorescent probes with integrated imaging and carrier functionalities have become excellent tools for molecular diagnostics and delivery of therapeutics molecules. Flexible surface chemistry, unique optical properties, high sensitivity, and multiplexing capabilities of QDs certainly make them a most promising tool for personalized medicine. This review focuses on state-of-art advances in synthesizing QDs and highlights the approaches used for functionalization of QDs with desired ligands for targeted carriage to specific sites. Discussed is the role of QDs in antitumor therapy through drug delivery and gene delivery and the recently emerged photodynamic therapy (PDT). We also endeavor to critically address the major impediments in the clinical development of these multifunctional nanoplatforms, with a special focus on plausible advancements for the near future.

Radiolabeled theranostics: magnetic and gold nanoparticles

“…Diagnostic and targeted affinity molecular imaging can be obtained by nanoscaled advanced materials, including: quantum dots (QDs), 24,51 solid lipid nanoparticles (SLNs), 5,52 liposomes, 33,53 metallic NPs, dendrimeric and polymeric NPs, 54 carbon nanotubes, 55 micelles, 56,57 and iodinated NPs. 58,59 Biologically, appropriate synchronic molecular reactions, such as sufficient adhesion strength with cell, are essential for NPs/NSs intended for overcoming hydrodynamic forces persuaded via blood circulation and remaining on cell surface in the living organisms.…”

Inorganic Nanoparticles Applied for Active Targeted Photodynamic Therapy of Breast Cancer

“…Quantum dots are a subclass of fluorescent nanomaterials, which have unique chemical and physical properties compared to organic dyes [89]. They have been utilized as multifunctional nanocarriers for PDT thanks to their high quantum yields, simple surface modification, and tunable optical properties [90]. They are also excellent donors in fluorescence resonance energy transfer (FRET) applications [91].…”

“…The above QD-based BC PDT studies have paved a new avenue for researchers to synthesize various targeted-QDs against breast cancer. It has been reported that QDs have potential cytotoxicity under UV irradiation to act as efficient PSs [90]. Furthermore, NIR fluorescent QDs provide improved PS water solubility, chemical stability, and low optical interference with biological tissues in PDT cancer treatments, when compared to small molecule-based PSs administered alone [94].…”

“…Furthermore, NIR fluorescent QDs provide improved PS water solubility, chemical stability, and low optical interference with biological tissues in PDT cancer treatments, when compared to small molecule-based PSs administered alone [94]. Additionally, the large surface area of QDs also enables the conjugation of multiple PSs and ligands for targeted photodynamic imaging [90]. Nevertheless, one of the most controversial problems with QD-based PDT is the high toxicity they possess, since most consist of toxic heavy metals, such as cadmium ions, and so they tend to be under investigated [90,95].…”

“…Additionally, the large surface area of QDs also enables the conjugation of multiple PSs and ligands for targeted photodynamic imaging [90]. Nevertheless, one of the most controversial problems with QD-based PDT is the high toxicity they possess, since most consist of toxic heavy metals, such as cadmium ions, and so they tend to be under investigated [90,95]. In order to alleviate some of these issues cadmium free QDs, such as zinc and indium based QDs [96], substituted with other elements, such as silicon or carbon [97], or their incorporation into polymeric NPs [98] have been proposed to enhance their application in diagnostic applications and PDT cancer clinical trials [99].…”