Disclosed herein are stable and versatile protein nanoparticles having a range of tunable fluorescent properties. Such nanoparticles may find utility in biological imaging. Methods of synthesis of such nanoparticles are also disclosed.

Reagents, assays, methods, kits, devices, and systems for rapid measurement of cholesterol and cholesterol sub-fractions from a blood sample are provided. Total cholesterol, low density lipoprotein cholesterol, and high density lipoprotein cholesterol can be measured in a single assay using kinetic measurements, under conditions in which cholesterol sub-species are converted to a detectable product at distinct rates. The detectable product is measured at different times after assay initiation. A lipase, cholesterol esterase, cholesterol oxidase and a peroxidase may be used together to produce colored product in amounts directly proportional to the quantity of cholesterol converted. Methods for calculating very-low density lipoprotein cholesterol levels by further including triglyceride measurements are disclosed. Assays may be performed in a single reaction mixture, allowing more accurate and precise cholesterol determinations, including ratios of cholesterol sub-fractions to total cholesterol, at less expense, than would be expected by performing several different assays in different reaction mixtures.

A biosensor for detecting triglycerides. The biosensor includes screen printed carbon electrodes (SPCEs), immobilised lipase and one or more other immobilised enzyme(s).

Provided herein are methods, systems, and compositions for Lp-PLA2 detection assays that employ amounts of detergent to liberate all or nearly all of the Lp-PLA2 molecules from associated lipoprotein particles. In this regard, the true Lp-PLA2 concentration can be detected in a sample, which correlates better with known Lp-PLA2 activity assays.

Provided is a compound comprising the structure:
(SIG)-(SI-MOD).sub.m. In this compound, SIG is a signaling molecule, SI is a self-immolative structure bound to SIG such that SIG has a reduced signal relative to the signal of SIG without SI, MOD is a moiety bound to SI that is subject to modification by an activator, and m is an integer from 1 to about 10. With this compound, when MOD is modified by an activator, SI is destabilized and self-cleaved from SIG such that SIG generates an increased signal. Also provided is a method of determining whether a sample comprises an activator, using the above-described compound. Additionally provided is a method of determining whether a cell comprises a nitroreductase using the above-described compound where nitroreductase is the activator. Further provided is a method of determining whether a mammalian cell is hypoxic using the above-described compound where nitroreductase is the activator. A method of detecting a microorganism that comprises a nitroreductase, using the above-described compound where nitroreductase is the activator, is also provided. Also provided is a method of identifying nitroreductase in a sample, using the above-described compound where nitroreductase is the activator.

A biosensor for detecting a biomarker in a bodily fluid, secretion or exudation is described that includes a first electrode, a second electrode, an electrode coating and a mechanical electrode stabilizer. The biomarker is an enzyme catalyzing a chemical reaction in which a singularity or plurality of constituents of the electrode coating are chemically altered by the breaking of covalent chemical bonds when being in contact with the same. The electrode coating can be a natural or synthetic substrate of the biomarker. The first electrode and the second electrode are electrically conductive and are kept in a substantially constant and uniform distance from each other by means of the mechanical electrode stabilizer. The exposed electrically conductive surface of at least one of the first electrode and the second electrode are substantially fully covered by the electrode coating.