IgG antibodies mediated gold nanoparticles conjugated to methotrexate as targeted chemotherapy for lung cancer.

Vincamine, a natural chemical, was used as a reducing agent in the synthesis of IgG antibodies mediated biogenic gold nanoparticles (IgGAuNPs). Eventually, the synthesised IgGAuNPs were bioconjugated with the chemotherapeutic drug methotrexate (MTX-IgGAuNPs). The IgG isotype can target cancer cells through polymorphic Fc gamma receptors (FcγRs) and have therapeutic effects. They can restrict cell division by inhibiting different intracellular signal transduction pathways and activating NK cells and macrophages through antibody-dependent cellular cytotoxicity and macrophage-mediated antibody-dependent phagocytosis, respectively. Further, IgGAuNPs and MTX-IgGAuNPs were characterised by physical techniques. Moreover, 3D conformational changes in the structure of IgG were analysed by fluorescence spectroscopy during and after the synthesis of IgGAuNPs. Furthermore, the IgGAuNPs and MTX-IgGAuNPs were effective against lung cancer (A549 cells), while they were found to be non-toxic against normal cells (NRK cells). The effectiveness of IgGAuNPs and MTX-IgGAuNPs was examined by MTT cytotoxicity assay, DCFDA method for the production of ROS, and release of Cyt-c from the mitochondria for caspase-3-mediated apoptosis. Moreover, the confirmation of internalisation of particles into the nucleus was examined under the DAPI assay, and it was found that particles caused nuclear fragmentation, which was also an indication of apoptosis.