Provided are novel rhodol-based compounds, the preparation method thereof, and use thereof in Tl.sup.+ flux assays. The disclosed compounds may be used as more red-shifted and less pH-sensitive variants of Thallos.

Compositions and methods for detecting the activity of an ion channel in a cell are described. The methods include providing a loading buffer solution to the cell, where the loading buffer includes a thallium ion indicator and optionally chloride ions, and providing a stimulus buffer that includes thallium ions to the cell. Providing the stimulus buffer can cause thallium ion influx into or efflux out of the cell through the ion channel. After providing the stimulus buffer, a change in at least one optical property of the thallium ion indicator is detected in response to thallium influx or efflux, thereby detecting the activity of the ion channel.

The subject of the invention is RNA analogs, their preparation and application, inter alia, in microscopic observations, study of the gene expression process and monitoring of enzyme activity.

The present application provides a liposomal composition that multivalently displays a specific glycan ligand, or combination of specific glycan ligands, to specifically target CD33 on microglial cells. Multivalent engagement of CD33 with glycan ligands in the liposomal composition are useful in modulating microglial cell function, particularly as a therapeutic for the preventing, treating or delaying progression of Alzheimer's disease.

There provided, inter alia, reagents and methods for modulation fluorescence of a tetrazine containing compound and/or a dienophile-containing compound. There is provided a method of detecting binding of a first affmity ligand and a second affinity ligand, the method includes the follow steps. Contacting a tetrazine-containing compound with a dienophile-containing compound, the tetrazine-containing compound comprising a first affinity ligand covalently attached to a tetrazine moiety and the dienophile-containing comprising a second affmity ligand covalently attached to a dienophile moiety.

Provided herein are improved fluorogenic compounds and probes that can be used as reagents for measuring, detecting and/or screening peroxynitrite. The fluorogenic compounds of the invention can produce fluorescence colors, such as green, yellow, red, or far-red. Also provided herein are fluorogenic compounds for selectively staining peroxynitrite in the mitochondria of living cells. Provided also herein are methods that can be used to measure, directly or indirectly, the presence and/or amount of peroxynitrite in chemical samples and biological samples such as cells and tissues in living organisms. Also provided are high-throughput screening methods for detecting or screening peroxynitrite or compounds that can increase or decrease the level of peroxynitrite in chemical and biological samples.