Incorporating nanotechnology into fluorescent imaging and magnetic resonance imaging
(MRI) has shown promising potential for accurate diagnosis of cancer at an earlier stage than the conventional
imaging modalities. Molecular imaging (MI) aims to quantitatively characterize, visualize, and
measure the biological processes or living cells at molecular and genetic levels. MI modalities have been
exploited in different applications including noninvasive determination and visualization of diseased
tissues, cell trafficking visualization, early detection, treatment response monitoring, and in vivo visualization
of living cells. High-affinity molecular probe and imaging modality to detect the probe are the
two main requirements of MI. Recent advances in nanotechnology and allied modalities have facilitated
the use of nanoparticles (NPs) as MI probes. Within the extensive group of NPs, fluorescent NPs play a
prominent role in optical molecular imaging. The fluorescent NPs used in molecular and cellular imaging
can be categorized into three main groups including quantum dots (QDs), upconversion, and dyedoped
NPs. Fluorescent NPs have great potential in targeted theranostics including cancer imaging, immunoassay-
based cells, proteins and bacteria detections, imaging-guided surgery, and therapy. Fluorescent
NPs have shown promising potentials for drug and gene delivery, detection of the chromosomal
abnormalities, labeling of DNA, and visualizing DNA replication dynamics. Multifunctional NPs have
been successfully used in a single theranostic modality integrating diagnosis and therapy. The unique
characteristics of multifunctional NPs make them potential theranostic agents that can be utilized concurrently
for diagnosis and therapy. This review provides the state of the art of the applications of
nanotechnologies in early cancer diagnosis focusing on fluorescent NPs, their synthesis methods, and
perspectives in clinical theranostics.
Gold Nanoshell Bioconjugates Used for Molecular Imaging in Living Cells
