Described are methods of treating a cancer comprising administering to a subject in need thereof an effective amount of a dopamine receptor (DR) antagonist. The DR antagonist may be a phenothiazine derivative, such as thioridazine or chlorpromazine. Optionally, the cancer is acute myeloid leukemia. Also described are methods for identifying subjects with cancer, methods for providing a prognosis for a subjects with cancer and methods for identifying subjects likely to be responsive to therapy with DR receptor antagonists. Methods for identifying cancer stem cells and chemotherapeutic compounds that are DR receptor antagonists as also provided. Also described are methods for the identification and validation of agents that target cancer stem cells.

The present invention provides a device for detecting an analyte in a liquid sample, including: a test element for testing presence or a quantity of the analyte in the liquid sample, where the analyte is one or more of analytes of: neopterin; homocysteine; dopamine; or microalbuminuria.

Provided herein are methods, compositions, kits and systems for in-solution assays of G-Protein Coupled Receptor (GPCR) activity. In particular, provided herein are methods, compositions, kits and systems comprising a fusion protein comprising a GPCR and a first nanoluciferase subunit, a GPCR conformation specific binder bound to a second nanoluciferase subunit wherein the GPCR conformation specific binder binds to an active GPCR, and a bioluminescent substrate to detect GPCR activation when the GPCR is bound to a ligand or drug in solution.

Described herein are sensors for detecting an analyte of interest in a sample. These sensors can comprise a potentiometric sensor comprising a surface functionalized with a pH-sensitive aptamer switch that specifically binds the analyte of interest, wherein the pH-sensitive aptamer switch is operatively coupled to the potentiometric sensor such that binding of the analyte of interest by the pH-sensitive aptamer switch induces a measurable change in the potentiometric sensor; and an auxiliary electrode in proximity to the surface, wherein the electrode is configured to alter a pH of a microenvironment in contact with the surface, thereby reversibly shuttling the pH-sensitive aptamer switch between a first state wherein it specifically binds the analyte of interest and a second state wherein it does not specifically bind the analyte of interest.

Described herein are compositions and methods for bioluminescent analyte detection. In some embodiments, a recombinant bioluminescent polypeptide sensor is disclosed comprising a luminescent signaling domain, an analyte binding domain, and one or more peptide linkers, wherein the luminescent signaling domain is oriented in relation to the analyte binding domain such that binding of an analyte to the analyte binding domain induces a conformational change in the luminescent signaling domain to generate a luminescent signal.

A dopamine (DA) sensor includes a glassy carbon electrode including an indium oxide doped zinc oxide (In.sub.2O.sub.3-doped ZnO) decorated mesoporous carbon (In.sub.2O.sub.3.Math.ZnO@MC) nanocomposite material. The In.sub.2O.sub.3.Math.ZnO@MC includes aggregates of spherical In.sub.2O.sub.3 nanoparticles (NPs) and cubic ZnO NPs dispersed on the surface of the mesoporous carbon.