Smart Core−Shell Hybrid Nanogels with Ag Nanoparticle Core for Cancer Cell Imaging and Gel Shell for pH-Regulated Drug Delivery

Multifunctional nanoparticles that can provide long circulation and specific accumulation, illuminate the targeted object, and intelligently dose the pathological zones will enable major advancements in diagnosis and therapy. To facilitate a simultaneous tumor-cell imaging and adequate local delivery to the tumor site, we develop core−shell structured hybrid nanogels (40−80 nm) composed of a Ag nanoparticle (NP) as core and smart gel of poly( N -isopropylacrylamide- co -acrylic acid) as shell. The pH-induced shrinkage of the nanogel increases the UV−vis absorption intensity and causes a blue shift of the surface plasmon bands of the Ag NP core. The smart nanogel can overcome cellular barriers to enter the intracellular region and light up the mouse melanoma B16F10 cells, including the nuclear regions. The surface property and concentrations of the hybrid nanogels influences their interactions with cells, resulting in different cell morphology and selective cell staining. The pH-responsive hybrid nanogels exhibit not only a high drug loading capacity but also a pH-controllable drug releasing behavior. Smart hybrid nanogels with optical and therapeutic functionality, designed by integration of functional building blocks, offer broad opportunities for biomedical applications.