Degradation of gold nanoparticle are one of challenges for it to be accepted for clinical translation. Silver is a common component to synthesize gold nanoparticles with a variety of shapes and physicochemical properties. Reactive oxygen species (ROS) can dissolve silver in gold nanoparticles by selective corrosion. Here, based on degradable property of silver under ROS, we designed ROS-degradable branched gold nanostructure (DBGNP) composed of gold and silver blocks connected each other for structural collapse by ROS induced dissolution of silver which interconnects gold blocks. We optimized a synthetic protocol for DBGNP and characterized the reactivity and degradability of DBGNP in various ROS-producing conditions. DBGNP with highly branched structure without core-structure was synthesized. The average hydrodynamic diameter of DBGNP was 206.4 nm. DBGNP was composed of gold and silver in the ratio of 10.55 to 1. The elemental distribution of gold and silver composing DBGNP was determined by STEM. After the basic characterization of DBGNP, Various ROS inducing conditions (H2O2 solution/Ce6+652-nm Laser/X-ray) were tested to DBGNP. The increase of H2O2 concentration caused the decrease of hydrodynamic size of DBGNP, and the newly generated population of small gold nanoparticles was detected by DLS. Moreover, the time-dependent degradation of DBGNP treated with H2O2 was also observed by TEM and DLS. Triggered release of model drug and degradation of DBGNP by exogenous production of ROS was also detected. Furthermore, intratumorally injected DBGNP showed CT contrast effect, and the intensity of contrast effect was decreased after treatment of photosensitizers and PDT laser, indicating that the enhanced elimination of DBGNP by degradation in the presence of ROS. Uniquely composed metallic nanostructure of DBGNP enabled degradability of gold particles in the presence of ROS. This finding will expand the usage of nanogold as a drug carrier with triggered release of therapeutics and overcome the current clinical concerns.

ROS induced structural collapse of alternatively connected gold and silver nano-branches

ACS Spring 2022

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