Semiconductor quantum dots (QDs) have captivated researchers in the biomedical field over the last decade. Compared to organic dyes and fluorescent proteins, QDs have unique optical properties such as tunable emission spectra, improved brightness, superior photostability, and simultaneous excitation of multiple fluorescence colors. Since the first successful reports on the biological use of QDs a decade ago, QDs and their bioconjugates have been successfully applied to various imaging applications including fixed cell labeling, live-cell imaging, in situ tissue profiling, fluorescence detection and sensing, and in vivo animal imaging. In this review, we will briefly survey the optical properties of QDs, the biofunctionalization strategies, and focus on their biosensing and in vivo imaging applications. We conclude with a discussion on the issues and perspectives on QDs as biosensing probes and in vivo imaging agents.
"While nearly all carboxy-terminated ligands limit QDs dispersion to basic pH, silica shell encapsulation provides stability over much broader pH range. The third method maintains native ligands on the QDs and uses variants of amphiphilic diblock and triblock copolymers and phospholipids to tightly interleave the alkylphosphine ligands through hydrophobic interactions (Michalet et al. 2005; Xing et al. 2009). Aside from rendering water solubility, these surface ligands play a critical role in insulating, passivating and protecting the QD surface from deterioration in biological media (Cai et al. 2007). "
[Show abstract][Hide abstract] ABSTRACT: Cellular and tissue imaging in the near-infrared (NIR) wavelengths between 700 and 900 nm is advantageous for in vivo imaging because of the low absorption of biological molecules in this region. This unit presents protocols for small animal imaging using planar and fluorescence lifetime imaging techniques. Included is an overview of NIR fluorescence imaging of cells and small animals using NIR organic fluorophores, nanoparticles, and multimodal imaging probes. The development, advantages, and application of NIR fluorescent probes that have been used for in vivo imaging are also summarized. The use of NIR agents in conjunction with visible dyes and considerations in selecting imaging agents are discussed. We conclude with practical considerations for the use of these dyes in cell and small animal imaging applications.
Current protocols in cytometry / editorial board, J. Paul Robinson, managing editor ... [et al.] 04/2012; Chapter 12:Unit12.27. DOI:10.1002/0471142956.cy1227s60
[Show abstract][Hide abstract] ABSTRACT: Sensitive and detailed molecular structural information plays an increasing role in molecular biophysics and molecular medicine.
Therefore, vibrational spectroscopic techniques, such as Raman scattering, which provide high structural information content
are of growing interest in biophysical and biomedical research. Raman spectroscopy can be revolutionized when the inelastic
scattering process takes place in the very close vicinity of metal nanostructures. Under these conditions, strongly increased
Raman signals can be obtained due to resonances between optical fields and the collective oscillations of the free electrons
in the metal. This effect of surface-enhanced Raman scattering (SERS) allows us to push vibrational spectroscopy to new limits
in detection sensitivity, lateral resolution, and molecular structural selectivity. This opens up exciting perspectives also
in molecular biospectroscopy. This article highlights three directions where SERS can offer interesting new capabilities.
This includes SERS as a technique for detecting and tracking a single molecule, a SERS-based nanosensor for probing the chemical
composition and the pH value in a live cell, and the effect of so-called surface-enhanced Raman optical activity, which provides
information on the chiral organization of molecules on surfaces.
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