tandem scfv production 

Tandem scFv-Fc BsAb is an IgG-like antibody with two single chain variable domains targeting distinct antigens. When constructing a Tandem scFv-Fc BsAb expression vector, genes coding each single-chain variable domain are tandem arrayed to a human Fc gene. Hence, the heterodimer that consists of these two chains is the desired bispecific antibody.
https://www.creativebiolabs.net/tandem-scfv-fc-bispecific-antibody-bsab.htm