Biomedical Engineering Reference
In-Depth Information
Chapter 3
Quantum Dot-Fluorescence-Based
Biosensing
Abstract
Since the emergence of quantum dots (QDs), their excellent fluorescent
properties have been widely used in the fabrication of biological sensors for vari-
ous analytes, such as metal ions, environmental samples, protein, deoxyribonucleic
acid (DNA), and ribonucleic acid (RNA). More importantly, some of these sensors
can realize not only fixed cell labeling, imaging of live cell dynamics, in situ tissue
profiling, but also in vivo animal imaging. A lot of reviews have well summarized
these in vitro diagnostic applications and in vivo imaging and sensing applications
of QDs. In this chapter, we mainly focus on QDs-fluorescence-based biosensing in
DNA, RNA, and DNA microarrays. The introduction of QDs in this aspect promoted
the sensitivity, stability, and diversity of DNA and RNA detection obviously.
Keywords
Quantum dots • DNA biosensor • Fluorescence • RNA analysis • DNA
microarray
3.1 QDs for DNA Analysis
3.1.1 Main Types for DNA Detection
As illustrated in the introduction part, deoxyribonucleic acid (DNA) biosensing has
important significance because of the useful information they possess for disease
diagnosis. One simple type of DNA detection systems is based on the hybridization
between a DNA target and its complementary probe, where DNA target is commonly
directly labeled with QDs. However, such modification of DNA target has less feasibil-
ity in practice. For better applications, other types of DNA biosensors such as sand-
wich structure, competitive system, and molecular beacon (MB) have been studied a
lot during the past decades (Fig.
3.1
). Fluorescence resonance energy transfer (FRET)
has been widely employed in these kinds of DNA biosensors. FRET is a nonradiative
process whereby an excited-state donor D (usually a fluorophore) transfers energy to a
