Green Synthesis of Gold Nanoparticles Using Carrageenan Oligosaccharide and Their In Vitro Antitumor Activity

Gold nanoparticles (AuNPs) have been widely used in catalysis, photothermal therapy, and targeted drug delivery. Carrageenan oligosaccharide (CAO) derived from marine red algae was used as a reducing and capping agent to obtain AuNPs by an eco-friendly, efficient, and simple synthetic route for the first time. The synthetic conditions of AuNPs were optimized by response surface methodology (RSM), and the CAO-AuNPs obtained were demonstrated to be ellipsoidal, stable and crystalline by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The CAO-AuNPs showed localized surface plasmon resonance (LSPR) oscillation at about 530 nm with a mean diameter of 35 ± 8 nm. The zeta potential of CAO-AuNPs was around −20 mV, which was related to the negatively charged CAO around AuNPs. The CAO-AuNPs exhibited significant cytotoxic activities to HCT-116 and MDA-MB-231 cells, which could be a promising nanomaterial for drug delivery.