Research focusing on
the intersection of life sciences and nanotechnology is producing new fields
such as nanobiotechnology, nanobiology and nanomedicine. This interaction is
occurring in both directions. On one hand, biological molecules can be used to
synthesize and organize inorganic functional nanomaterials into well-defined
structures (Ma and others, 2008; Sotiropoulou and others, 2008; van Bommel and
others, 2003). On the other hand, nanomaterials can be used to study biology
and develop biomedicines. For example, labeled nanomaterials can serve as
effective longlasting dyes for bio-imaging (Lee and others, 2007; Medintz and
others, 2005; Xie and others, 2011) and nanomaterials are ideal drug-carriers
for the development of new drug systems (Dobson, 2006; Nakanishi and others,
2009; Portney and Ozkan, 2006). Microscopy is a powerful tool that can image
bionanostructures, track nanomaterials in bio-systems, measure physical
properties, determine compositions, and even create and manipulate
nanostructures. In this special issue on bio-nano imaging and analysis,
different microscopy techniques were used to characterize the structures of
bionanomaterials, image nanoparticles in biological systems, study biological
functions, or manipulate nanostructures (Figure 1). This special issue includes
13 articles from leading scientists in bionanotechnology and the microscopy community
and covers the following four interesting topics: 1) use of nanoparticles as
imaging probes, 2) manipulation of nanostructures using microscopy, 3)
bio-inorganic hybrid nanomaterials imaging, and 4) imaging nanomaterials using
fluorescence and single-molecule microscopy. In this special issue the first
topic is about the use of nanoparticles as imaging probes. Four frequently used
nanoparticles and their principal method of imaging are summarized in table 1.
This section includes three review articles and one research article. The three
review articles concern recent advancements in the application of gold
nanoparticles, magnetic nanoparticles and quantum dots for bio-imaging. The
research article presents a special method for labeling axonal transport with
quantum dots. Subramanian Tamil Selvan et al, at the Institute of Materials
Research and Engineering in Singapore have reviewed the recent advances in the
synthesis and application of bimodal magnetic-fluorescent probes for
bio-imaging (pages 563–576). Recent advances in imaging with nanoparticles,
which include quantum dots, magnetic nanoparticles, rare-earth doped
upconversion fluorescent nanoparticles, and multifunctional nanoparticles have
been very rapid. These nanoparticles have not only enhanced imaging
sensitivity, resolution, and specificity, but they have also allowed for
simultaneous multi-targeting, monitoring, and enhanced diagnostics and delivery
of therapeutic effects. In the second part of this article, molecular imaging
modalities clinically used such as position emission tomography (PET), single
photon emission computed tomography (SPECT), magnetic resonance imaging (MRI),
optical and and ultrasound microscopy are summarized in a table along with the
related imaging methods for the specific nanoparticles. Also described are
recent advances in the assemblies of (1) superparamagnetic iron oxide
(SPIO)-quantum dot (QD) based magnetic-fluorescent probes, (2) SPIOrare-earth
(RE) based magnetic-fluorescent probes, (3) Gd-based magnetic contrast agents
covalently attached to fluorescent probes, and (4) Gd-based MRI agents and
fluorescent probes in a single nanomaterial domain. This article should be
important to those studying nanomaterials for bio-imaging. The next article by
Jesús Ruiz-Cabello from Universidad Complutense de Madrid, Madrid, Spain
described use of magnetic iron oxide nanoparticles and gold nanoparticles
(GNPs) in MRI imaging and gene therapy (Pages 577–591). The magnetic
nanoparticles are good contrast enhancement agents in MRI imaging. They can
also be magnetically manipulated to guide delivery of genes into target cells
for transfection. When GNPs are modified with either Gd supramolecular
complexes or iron oxide, the new conjugates can also serve as contrast
enhancement agents in MRI. More importantly, they elucidate the conjugation of
these nanoparticles with biological molecules such as viruses to form
nanobioconjugates. This article summarizes how these nanobioconjugates can
improve the performance of the nanoparticles in MRI imaging and gene therapy.
This article should be useful for those who are studying magnetic
nanoparticles-based MRI imaging and gene delivery. The article by Eliza Hutter
and Dusica Maysinger, McGill University in Canada, reviews the unique properties
of GNPs and QDs, and how their properties benefit cellular and in vivo imaging
(pages 592–604). GNPs have strong light scattering and surface plasmon enhanced
luminescence, both of which can be used for bio-imaging. Light scattering by
GNPs is usually visualized by dark-field microscopy and surface plasmon
enhanced luminescence is most commonly monitored by two-photon luminescence
microscopy. In the first part of this issue are described the physicochemical
characteristics of GNPs, how to apply GNPs in the imaging of cells and animals,
advantages of applying GNPs, and other potential applications of GNPs. QDs,
which are stable, highly fluorescent, and tunable nanoparticles, can be further
functionalized for specific applications. In the second part of this article,
the authors reviewed the use of QDs as bio-imaging probes to image protein
location at cellular or the intracellular organelle surfaces, to screen cancer
markers in biological fluids, and to diagnose primary and metastatic tumors in
vivo. This article introduces two very useful nanoparticles, luminescent QDs
and plasmonic GNPs, VC 2011 WILEY-LISS, INC.