title: "Mixed-charge self-assembled monolayers" as a facile method to design pH-induced aggregation of large gold nanoparticles for near-infrared photothermal cancer therapy.
abstract: The acidic microenvironment of tumor tissues has proven to be one of the major differences from other normal tissues. The near-infrared (NIR) light irradiation of aggregated gold nanoparticles in a tumor acidic pH-induced manner could then provide an effect approach to treat solid tumors with the advantage of minimizing the undesired damage to normal tissues. Although it is well-known the aggregation of larger nanoparticles will result in a better NIR photothermal effect, the preparation of pH-sensitive gold nanoparticles in large sizes remains a big challenge because of their worse dispersive stability. In this paper, we introduce a facile way to endow large gold nanoparticles with tunable pH-aggregation behaviors by modifying the nanoparticle surface with mixed-charge self-assembly monolayers compromising positively and negatively charged thiol ligands. Four different size nanoparticles were used to study the general principle of tailoring the pH-induced aggregation behaviors of mixed-charge gold nanoparticles (MC-GNPs) by adjusting the surface ligand composition. With proper surface ligand composition, the MC-GNPs in four different sizes that all exhibited aggregation at tumor acidic pH were obtained. The biggest MC-GNPs showed the most encouraging aggregation-enhanced photothermal efficacy in vitro when they formed aggregates. The mixed-charge self-assembled monolayers were then proved as a facile method to design pH-induced aggregation of large gold nanoparticles for better NIR photothermal cancer therapy.
authors.affiliation: MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Li
authors.forename: Xiangsheng
authors.initials: X
authors.lastname: Liu
authors.forename: Nan
authors.initials: N
authors.lastname: Huang
authors.forename: Kefeng
authors.initials: K
authors.lastname: Ren
authors.forename: Qiao
authors.initials: Q
authors.lastname: Jin
authors.forename: Jian
authors.initials: J
authors.lastname: Ji
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D056945:Hep G2 Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D010789:Phototherapy / Q000379:methods*; D059016:Tumor Microenvironment
chemical_list: D000970:Antineoplastic Agents; D006046:Gold
keywords: mixed-charge gold nanoparticles; near-infrared (NIR) photothermal therapy; pH-induced aggregation; size effect