Omid Mashinchian
1,2, Mohammad Johari-Ahar
1, Behnaz Ghaemi
2, Mohammad Rashidi
1,3, Jaleh Barar
1* 
, Yadollah Omidi
1* 1 Research Center for Pharmaceutical Nanotechnology, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
2 Department of Medical Nanotechnology, School of Advanced Technologies in Medicine (SATiM), Tehran University of Medical Sciences, Tehran, Iran
3 Department of Photonics, School of Engineering-Emerging Technology, University of Tabriz, Tabriz, Iran
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.