A polynucleotide encoding a biosensor polypeptide comprising a modified circularly-permuted thermostable luciferase and a linker linking the C-terminal portion of the thermostable luciferase to the N-terminal portion of the thermostable luciferase. The container incorporates a transparent front sheet made from a planar layer of a polymer and an opposing rear sheet. The bracket section has a second cross-sectional shape and is releasably coupled to the mounting section to form a first gripping section.