Biomaterial Database

A self-assembled quantum dot probe for detecting beta-lactamase activity. 2006

Chenjie Xu, and Bengang Xing, and Jianghong Rao

Biophysics, Cancer Biology, and Molecular Imaging Programs, Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305, USA.

This communication describes a quantum dot probe that can be activated by a reporter enzyme, beta-lactamase. Our design is based on the principle of fluorescence resonance energy transfer (FRET). A biotinylated beta-lactamase substrate was labeled with a carbocyanine dye, Cy5, and immobilized on the surface of quantum dots through the binding of biotin to streptavidin pre-coated on the quantum dots. In assembling this nanoprobe, we have found that both the distance between substrates and the quantum dot surface, and the density of substrates are important for its function. The fluorescence emission from quantum dots can be efficiently quenched (up to 95%) by Cy5 due to FRET. Our final quantum dot probe, assembled with QD605 and 1:1 mixture of biotin and a Cy5-labeled lactam, can be activated by 32microg/mL of beta-lactamase with 4-fold increase in the fluorescence emission.

UI	MeSH Term	Description	Entries
D005456	Fluorescent Dyes	Chemicals that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.	Flourescent Agent,Fluorescent Dye,Fluorescent Probe,Fluorescent Probes,Fluorochrome,Fluorochromes,Fluorogenic Substrates,Fluorescence Agents,Fluorescent Agents,Fluorogenic Substrate,Agents, Fluorescence,Agents, Fluorescent,Dyes, Fluorescent,Probes, Fluorescent,Substrates, Fluorogenic
D001618	beta-Lactamases	Enzymes found in many bacteria which catalyze the hydrolysis of the amide bond in the beta-lactam ring. Well known antibiotics destroyed by these enzymes are penicillins and cephalosporins.	beta-Lactamase,beta Lactamase,beta Lactamases
D013194	Staining and Labeling	The marking of biological material with a dye or other reagent for the purpose of identifying and quantitating components of tissues, cells or their extracts.	Histological Labeling,Staining,Histological Labelings,Labeling and Staining,Labeling, Histological,Labelings, Histological,Stainings
D015336	Molecular Probe Techniques	The use of devices which use detector molecules to detect, investigate, or analyze other molecules, macromolecules, molecular aggregates, or organisms.	Molecular Probe Technic,Molecular Probe Technics,Molecular Probe Technique,Technic, Molecular Probe,Technics, Molecular Probe,Technique, Molecular Probe,Techniques, Molecular Probe,Probe Technic, Molecular,Probe Technics, Molecular,Probe Technique, Molecular,Probe Techniques, Molecular
D045663	Quantum Dots	Nanometer sized fragments of semiconductor crystalline material which emit PHOTONS. The wavelength is based on the quantum confinement size of the dot. They can be embedded in MICROBEADS for high throughput ANALYTICAL CHEMISTRY TECHNIQUES.	Nanocrystals, Semiconductor,Semiconductor Nanocrystals,Semiconductor Nanoparticles,Dot, Quantum,Dots, Quantum,Nanocrystal, Semiconductor,Nanoparticle, Semiconductor,Nanoparticles, Semiconductor,Quantum Dot,Semiconductor Nanocrystal,Semiconductor Nanoparticle
D031541	Fluorescence Resonance Energy Transfer	A type of FLUORESCENCE SPECTROSCOPY using two FLUORESCENT DYES with overlapping emission and absorption spectra, which is used to indicate proximity of labeled molecules. This technique is useful for studying interactions of molecules and PROTEIN FOLDING.	Forster Resonance Energy Transfer