[Single-domain antibody - advances in research and application].

Conventional IgG is composed of heavy and light chains. The light chain has one variable region (VL) and one constant region (CL) domain, whereas the heavy chain has one variable region (VH) and three constant region domains (CH1, CH2 and CH3). Single domain antibody (sdAb) is a kind of antibody that is composed of a variable domain of heavy chain and devoid of the light chain completely. Due to its small size, it is also called as nanobody. Although the sdAb has a simple structure, it can exhibit a comparable even better antigen-binding affinity than conventional antibody. Compared with conventional antibody, the small size, high stability and simplicity in recombinant expression are representative advantages of sdAb. In recent years, scientists are becoming increasingly interested in the roles of sdAb in fundamental biomedical research and clinical application. In this review, we summarized the structural features, physicochemical properties, screening strategies and recent advances in application of sdAb.