We synthesized multimetal microrods intrinsically encoded with submicrometer stripes. Complex striping patterns are readily prepared by sequential electrochemical deposition of metal ions into templates with uniformly sized pores. The differential reflectivity of adjacent stripes enables identification of the striping patterns by conventional light microscopy. This readout mechanism does not interfere with the use of fluorescence for detection of analytes bound to particles by affinity capture, as demonstrated by DNA and protein bioassays.

Raman spectroscopy is a newly developed, noninvasive preclinical imaging technique that offers picomolar sensitivity and multiplexing capabilities to the field of molecular imaging. In this study, we demonstrate the ability of Raman spectroscopy to separate the spectral fingerprints of up to 10 different types of surface enhanced Raman scattering (SERS) nanoparticles in a living mouse after s.c. injection. Based on these spectral results, we simultaneously injected the five most intense and spectrally unique SERS nanoparticles i.v. to image their natural accumulation in the liver. All five types of SERS nanoparticles were successfully identified and spectrally separated using our optimized noninvasive Raman imaging system. In addition, we were able to linearly correlate Raman signal with SERS concentration after injecting four spectrally unique SERS nanoparticles either s.c. (R 2 ‫؍‬ 0.998) or i.v. (R 2 ‫؍‬ 0.992). These results show great potential for multiplexed imaging in living subjects in cases in which several targeted SERS probes could offer better detection of multiple biomarkers associated with a specific disease.imaging in vivo ͉ multiplex ͉ SERS ͉ nanoparticles I n recent years, the biomedical research community has come to realize that no single targeting agent is likely to provide sufficient information needed to characterize or detect a specific disease process. As a result, several efforts have been made toward the discovery of multiple biomarkers and targeting ligands in the hope of improving earlier detection and management of specific diseases. The ability to simultaneously detect multiple targets, sensitively and in vivo, is an attractive feat; but it is a task often difficult to accomplish. Thus far, nanoparticles have played an important role in this endeavor; however most nanostructure-based platforms for multiplex detection methods have been tailored for in vitro applications (1-6), leading to little progress in the field of in vivo multiplex imaging.Recently, there has been an overwhelming interest in sensitive imaging of nanoparticles for both diagnostic and therapeutic applications (7-11). As a result, new preclinical imaging modalities optimized for nanoparticle imaging have been developed, further expanding the field of molecular imaging. Thus far, fluorescence and Raman spectroscopy, in conjunction with quantum dots and surface enhanced Raman scattering (SERS) nanoparticles, respectively, have been the predominant imaging modalities to evaluate in vivo multiplex imaging (12)(13)(14). Raman imaging, in particular, has generated quite a bit of interest recently; we have demonstrated its ability to detect picomolar concentrations in vivo along with its unique ability to multiplex using SERS nanoparticles and others have developed novel Raman nanoparticles with the potential to be used in vivo as well (14-17).Both quantum dots and SERS nanoparticles have shown great potential as multiplexed imaging probes ex vivo, whether for cellular imaging or for biosensor applications; however, seve...

In this report, we present data demonstrating that cylindrical metallic particles, with various submicrometer striping patterns, may be readily distinguished in an optical microscope. Accurate particle identification is discussed relative to synthesis reproducibility and the limitations of optical microscopes. Results from a library of these particles, of which over 100 different striping patterns have been produced, are presented. For these particles, made with Au and Ag stripes, more than 70 patterns may be identified with greater than 90% accuracy. The ability to chemically modify the surface of these particles, making them useful for bioanalytical measurements, is also demonstrated. Finally, we discuss improvements in our manufacturing and identification processes that will lead to both larger numbers of striping patterns and improved identification accuracy.

No abstract

In this paper we describe a molecular beacon format assay in which encoded nanowire particles are used to achieve multiplexing. We demonstrate this principle with the detection of five viral pathogens; Hepatitis A virus, Hepatitis C virus, West Nile Virus, Human Immune Deficiency virus and Severe Acute Respiratory Syndrome virus. Oligonucleotides are designed complementary to a target sequence of interest containing a 3′ universal fluorescence dye. A 5′ thiol causes the oligonucleotides to self-assemble onto the metal nanowire. The single-stranded oligonucleotide contains a self-complementary hairpin stem sequence of 10 bases that forces the 3′ fluorophore to come into contact with the metallic nanowire surface, thereby quenching the fluorescence. Upon addition of target DNA, there is hybridization with the complementary oligonucleotides. The resulting DNA hybrid is rigid, unfolds the hairpin structure, and causes the fluorophore to be moved away from the surface such that it is no longer quenched. By using differently encoded nanowires, each conjugated with a different oligonucleotide sequence, multiplexed DNA assays are possible using a single fluorophore, from a multiplexed RT-PCR reaction.(Nanobiotechnology