GPC3 and hepatocellular carcinoma: To use heparin sulphate proteoglypican-3 (GPC3) as a targeting ligand for hepatocellular carcinoma, Liu et al. conjugated biotinylated GPC3 antibody to rGO (rGO-GPC3) and bind avidinylated nanobubbles to rGO-GPC3 using the biotin-avidin bioaffinity system for PTT.