Antibody has become a crucial tool for the detection and regulation of protein functions. It serves as a key element in immunodetection for disease diagnosis or laboratory sensing of biomarkers. However, limited cell permeability of antibodies restricts their usage towards experiments involving cell surface, body fluids or cell lysate.
Antibody delivery into live cells can be effective tools for live cell imaging and into-cell delivery technique. Though live cells do not uptake the antibody easily, several methods for internalization of antibody into live cells have been developed including electroporation, microinjection, and transfected gene mediated intracellular expression of antibody and each method is not without some drawbacks.
We have developed new antibody delivery methods using cell-penetrating peptides (CPPs) and IgG Fc domain-binding cyclic peptide conjugate (FcBP). CPPs have been employed for the cellular delivery of proteins, DNA or nanoparticles in the form of complexes. Several CPPs have been reported including penetratin, Arg8, HIV-1 TAT, MPS, etc. FcBP is a peptide ligand comprising a soluble surface linker and 13 amino acids, which specifically binds to Fc domain of IgG, and it has been utilized for capturing antibodies on various solid surfaces.
In this work, we constructed several antibody carriers, placed FcBP and CPPs via protein expression technique or chemical method using an adequate linker, and tested their usage for transduction of fluorescence-labeled antibodies. This represents the first peptide reagents enabling targeted antibody delivery into live cells avoiding any detergents or other physical methods.