Gold encapsulated chitosan-poly(acrylic acid) hybrid hollow nanospheres

Chitosan-poly(acrylic acid)-gold (CS-PAA-Au) hybrid hollow nanospheres were prepared by reducing gold salts to gold nanoparticles in chitosan-acrylic acid (CS-AA) aqueous solution, followed by polymerization of AA monomer and selectively crosslinking chitosan at the end of polymerization. The payload of Au nanoparticles within the CS-PAA hollow nanospheres could be controlled by varying the addition amount of gold salts in the reaction system. Transmission electron microscopy (TEM) revealed that multi-crystal gold nanoparticles were encapsulated inside the CS-PAA nanospheres. TEM and scanning electron microscopy (SEM) indicated that these hybrid nanospheres had a hollow structure. Energy-dispersive X-ray (EDX) spectroscopy confirmed the existence of gold nanoparticles inside the CS-PAA-Au hybrid nanospheres. These hollow CS-PAA-Au hybrid nanospheres showed a typical surface plasmon resonance (SPR) band of gold nanoparticles around 526 nm, and offered excellent stability at different temperatures and in acidic media. Also, no inhibition of cell proliferation and no cytotoxic effects were observed in the presence of CS-PAA-Au hybrid nanospheres, which renders them good candidates for potential application in biomedical fields.