Impacts of quantum dots in molecular detection and bioimaging of cancer

Abstract

Introduction: A number of assays have so far been exploited for detection of cancer biomarkers in various malignancies. However, the expression of cancer biomarker(s) appears to be extremely low, therefore accurate detection demands sensitive optical imaging probes. While optical detection using conventional fluorophores often fail due to photobleaching problems, quantum dots (QDs) offer stable optical imaging in vitro and in vivo. Methods: In this review, we briefly overview the impacts of QDs in biology and its applications in bioimaging of malignancies. We will also delineate the existing obstacles for early detection of cancer and the intensifying use of QDs in advancement of diagnostic devices. Results: Of the QDs, unlike the II-VI type QDs (e.g., cadmium (Cd), selenium (Se) or tellurium (Te)) that possess inherent cytotoxicity, the I-III-VI 2 type QDs (e.g., AgInS2, CuInS2, ZnS-AgInS2) appear to be less toxic bioimaging agents with better control of band-gap energies. As highly-sensitive bioimaging probes, advanced hybrid QDs (e.g., QD-QD, fluorochrome-QD conjugates used for sensing through fluorescence resonance energy transfer (FRET), quenching, and barcoding techniques) have also been harnessed for the detection of biomarkers and the monitoring of delivery of drugs/genes to the target sites. Antibody-QD (Ab-QD) and aptamer- QD (Ap-QD) bioconjugates, once target the relevant biomarker, can provide highly stable photoluminescence (PL) at the target sites. In addition to their potential as nanobiosensors, the bioconjugates of QDs with homing devices have successfully been used for the development of smart nanosystems (NSs) providing targeted bioimaging and photodynamic therapy (PDT). Conclusion: Having possessed great deal of photonic characteristics, QDs can be used for development of seamless multifunctional nanomedicines, theranostics and nanobiosensors.

Applications of Fluorescent Quantum Dots for Reproductive Medicine and Disease Detection

“…In the case of CdSe QDs, it is believed that properly prepared closed (ZnS) or multiple (e.g., ZnS/SiO 2 , ZnS/PEG hydrophilic coating) shells render cadmium leakage less likely [29,30]. However, oxidized QDs surface may unintendedly react with intracellular components, causing formation and release of reduced Cd that results in apoptosis within primary hepatocytes isolated from rats [31][32][33]. In addition, the charge and chemical reactivity of QDs play dominant roles in their biocompatibility, independent of their size [32].…”

“…The brightness of CdSe QDs fluorescence has made them the widely labeled nanoparticles for various biosensing (e.g., oligonucleotides, organic dyes) and single or multiplex labeling (e.g., antibodies, peptides) [22,23,31,[55][56][57]]. Yet, the localization (intracellular or extracellular), expression level, and environment (oxidizing or reducing) of the target molecule should be considered during the QDs labeling protocol.…”

“…QDs functionalized with antibody are optimal for extracellular targeting of cell-surface membrane proteins (e.g., receptors) and subsequent targeted imaging [20,22,31], which practice will create opportunities for precise assessments of cellular and molecular mechanisms of diseases (e.g., cancer) and their treatments. Nearinfrared QDs (e.g., CdSe, CdTe) emit in the wavelength range of 650-900 nm to overcome the optical property variations and endogenous autofluorescence of tissues under in vivo conditions [67], permitting tumor localization and visualization while offering a new mean for cancer prevention and treatment.…”

Mirabilis Jalapa L. Protein as Inductor of Apoptosis on UVB-induced Skin Damage in Mice

“…Apoptosis detection with electrophoresis methods (modification of Saadat et al). 12 He Lacells (250 µl with a cell concentration of 5 x 10 5 mL -1…”

Photoluminescent nanoplatforms in biomedical applications

“…Since then, QDs have become the most popular nanomaterial employed to investigate cellular structures and functions. Thus, numerous review papers have been published on QDs cellular imaging [21,[94][95][96]. Au nanoparticles also have been exploited in cellular imaging.…”