Embodiments in accordance with the present disclosure include antibody binding domains that specifically bind to mesothelin. A nanobody or conjugate construct thereof can comprise the antibody binding domain comprising complementary determining region (CDR)1 of SEQ ID NO:05 or SEQ ID NO:08, CDR2 of SEQ ID NO:06 or SEQ ID NO:09, and/or CDR3 of SEQ ID NO:07 or SEQ ID NO:10. The nanobody or conjugate constructs of the nanobody can be used for diagnosis or treatment of diseases or conditions associated with overexpression of mesothelin.
