Magnetic Nanosensors for Probing Molecular Interactions
Magnetic nanosensors exhibiting high specificity and biocompatibility have been synthesized for the in vitro and in vivo detection of molecular interactions. Upon target-induced nanoassembly formation, a sensitive and dosedependent decrease in the spin-spin relaxation time (T2) of adjacent water molecules was observed. Various molecular targets ranging from DNAoligonucleotides, proteins, small molecules, and even whole viruses have been detected using this technology, with sensitivity in the low femtomole range (0.5–30 fmol). Furthermore, the engymatic activity of restriction endonucleases and proteases, among others, has also been detected using an alternate method, based on the enzyme-induced dispersion of nanoparticles from a pre-formed nanoassembly. Furthermore, this technique was used to monitor disease-associated enzymatic activity, such as up-regulated activity of telomerase, myeloperoxidase and caspase. The observed changes in T2 can be easily detected in water suspension of the magnetic nanosensors by existing magnetic resonance (NMR/MRI) techniques with minimal sample preparation and permitting high-throughput screening. Homogenous and high-throughput assays to selectively detect a variety of molecular targets in solution can be designed using this magnetic nanosensor technology. Finally, the presence of a target in whole blood or turbid media can be performed as the magnetic relaxation signal is independent of the optical properties of the solution.
KeywordsMagnetic Nanoparticles Magnetic Relaxation Superparamagnetic Iron Oxide Gadolinium Oxide Iron Oxide Core
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