The present disclosure is directed to optical probes. An optical probe can include a plasmonic core, a buffer layer on the plasmonic core, and a composite shell comprising a fluorophore embedded in a transparent metal oxide matrix. An optical probe can include a plasmonic core, a transparent shell encapsulating the core, and a plurality of Raman dyes proximate to the core and embedded in the transparent shell. An optical probe can include a plasmonic core comprising a nanoparticle; and a plurality of secondary nanoparticles proximate to the plasmonic core selected to provide plasmonic coupling to the plasmonic core by charge transfer. The optical probes can be useful in various detection systems, for example paper-based lateral flow strip assemblies, particularly where it is necessary to detect low levels of an analyte.

The disclosure provides methods of analyzing an analyte of interest in a biological sample using fluorescent agents and macroconjugates which comprise a core containing a cross-linked polymer or protein, tags, specific binding members or fragments thereof, and optionally carrier proteins. Also provided are methods of analyzing two or more analytes of interest in a biological sample in a single assay using microparticles and detection conjugates comprising different fluorophore labels, acquiring transmitted light and fluorescent images of the microparticles, and using a customized image analysis process to analyze the acquired images.

The present invention provides a fluorescent silica-based nanoparticle that allows for precise detection, characterization, monitoring and treatment of a disease such as cancer. The nanoparticle has a range of diameters including between about 0.1 nm and about 100 nm, between about 0.5 nm and about 50 nm, between about 1 nm and about 25 nm, between about 1 nm and about 15 nm, or between about 1 nm and about 8 nm. The nanoparticle has a fluorescent compound positioned within the nanoparticle, and has greater brightness and fluorescent quantum yield than the free fluorescent compound. The nanoparticle also exhibits high biostability and biocompatibility. To facilitate efficient urinary excretion of the nanoparticle, it may be coated with an organic polymer, such as poly(ethylene glycol) (PEG). The small size of the nanoparticle, the silica base and the organic polymer coating minimizes the toxicity of the nanoparticle when administered in vivo. In order to target a specific cell type, the nanoparticle may further be conjugated to a ligand, which is capable of binding to a cellular component associated with the specific cell type, such as a tumor marker. In one embodiment, a therapeutic agent may be attached to the nanoparticle. To permit the nanoparticle to be detectable by not only optical fluorescence imaging, but also other imaging techniques, such as positron emission tomography (PET), single photon emission computed tomography (SPECT), computerized tomography (CT), bioluminescence imaging, and magnetic resonance imaging (MRI), radionuclides/radiometals or paramagnetic ions may be conjugated to the nanoparticle.

Disclosed herein is a composition for ultrasensitive bioassay applications. The composition includes a plurality of dispersible, nanoparticles having a size less than 500 nm. The nanoparticles contain a metal catalyst or a metal catalyst precursor. The nanoparticles are conjugated to at least one biospecific binding reactant that is selectively reactive with a target analyte. The composition includes a dispersing medium. A method and a kit for conducting bioassays are described.

The present application relates to a method for detecting ligand using a biosensor applied the FRET (fluorescence resonance energy transfer) phenomenon. More particularly, the method may be used for simply detecting a ligand in a sample by measuring the FRET of a biosensor under the conditions in which a specific critical temperature is maintained. The method may use a phenomenon in which a ligand-binding protein in a biosensor shows reversible unfolding at a temperature higher than the specific critical temperature and the level of the unfolding changes depending on the concentration of a ligand. The method can be widely applied to a variety of kinds of FRET biosensors using the ligand-binding protein.

The present invention provides methods, devices, compositions (e.g., capture complexes), and kits useful for enhancing the detection of antibodies in a test sample. The methods, devices, and compositions utilize detectable Fc-binding molecules such as Protein A, Protein G, and/or an Fc-specific antibody to amplify the signal of a detected antibody in immunoassays, such as lateral flow assays.

A method of detecting one or more analytes comprising or consisting of hydrogen peroxide using surface enhanced Raman spectroscopy (SERS) is provided. The method includes providing a SERS-active substrate having at least one metal carbonyl cluster compound attached thereon; contacting one or more analytes with the SERS-active substrate; and detecting changes in surface enhanced Raman signal from the at least one metal carbonyl cluster compound as an indication of the presence of one or more analytes comprising or consisting of hydrogen peroxide.

Disclosed herein are diagnostic assays using surface enhanced Raman spectroscopy (SERS)-active particles, including liquid-based assays; magnetic capture assays; microparticle-nanoparticle satellite structures for signal amplification in an assay; composite SERS-active particles useful for enhanced detection of targets; and sample tubes and processes for using the same.

The invention provides a method for detecting the presence or absence of a biomarker in a biological sample at a very low concentration comprising the steps of (a) contacting the biological sample with a capture binding sequence immobilized on a surface, (b) providing a conjugate comprising a detection binding sequence-glucose oxidase, (c) contacting the surface with the detection binding sequence-glucose oxidase conjugate, (d) separating any unbound detection binding sequence-glucose oxidase conjugate from the surface, (e) incubating the resulting surface with a glucose solution and a mixture comprising gold nanoparticles and a gold salt, wherein the gold nanoparticles have an initial particle size of about 5 nm, and (f) observing any change in color of the mixture. The invention also provides a method for diagnosing the presence of a prostate cancer biomarker in a subject and a kit for detecting or quantifying a biomarker in a biological sample.

The present invention provides a method of producing core/shell-type fluorescent dye-containing nanoparticles for immunohistochemical staining or live cell imaging, the method including: the step 1 of polymerizing monomers for thermoplastic resin synthesis in the presence of a fluorescent dye and thereby preparing core particles composed of a thermoplastic resin containing the fluorescent dye; and the step 2 of coating the core particles each with a shell layer composed of a thermosetting resin. By the method of producing fluorescent dye-containing nanoparticles according to the present invention, fluorescent dye-containing nanoparticles having a high brightness, whose dye does not elutes into water, physiological saline, culture medium and the like, can be produced, and the fluorescent dye-containing nanoparticles can be effectively utilized in immunohistochemical staining and live cell imaging.