Near-Infrared-Absorbing Gold Nanopopcorns with Iron Oxide Cluster Core for Magnetically Amplified Photothermal and Photodynamic Cancer Therapy

We present the synthesis and application of a new type of dual magnetic and plasmonic nanostructures for magnetic-field-guided drug delivery and combined photothermal and photodynamic cancer therapy. Near-infrared-absorbing gold nanopopcorns containing a self-assembled iron oxide cluster core were prepared via a seed-mediated growth method. The hybrid nanostructures are superparamagnetic and show great photothermal conversion efficiency (η = 61%) under near-infrared irradiation. Compact and stable nanocomplexes for photothermal–photodynamic therapy were formed by coating the nanoparticles with near-infrared-absorbing photosensitizer silicon 2,3-naphthalocyannie dihydroxide and stabilization with poly­(ethylene glycol) linked with 11-mercaptoundecanoic acid. The nanocomplex showed enhanced release and cellular uptake of the photosensitizer with the use of a gradient magnetic field. <i>In vitro</i> studies using two different cell lines showed that the dual mode photothermal and photodynamic therapy with the assistance of magnetic-field-guided drug delivery dramatically improved the therapeutic efficacy of cancer cells as compared to the combination treatment without using a magnetic field and the two treatments alone. The “three-in-one” nanocomplex has the potential to carry therapeutic agents deep into a tumor through magnetic manipulation and to completely eradicate tumors by subsequent photothermal and photodynamic therapies without systemic toxicity

Gold Nanorods Carrying Paclitaxel for Photothermal-Chemotherapy of Cancer

Nanotechnology-based photothermal therapy has emerged as a promising treatment for cancer during the past decade. However, heterogeneous laser heating and limited light penetration can lead to incomplete tumor cell eradication. Here, we developed a method to overcome these limitations by combining chemotherapy with photothermal therapy using paclitaxel-loaded gold nanorods. Paclitaxel was loaded to gold nanorods with high density (2.0 × 10⁴ paclitaxel per gold nanorod) via nonspecific adsorption, followed by stabilization with poly­(ethylene glycol) linked with 11-mercaptoundecanoic acid. Paclitaxel was entrapped in the hydrophobic pocket of the polymeric monolayer on the surface of gold nanorods, which allows direct cellular delivery of the hydrophobic drugs via the lipophilic plasma membrane. Highly efficient drug release was demonstrated in a cell membrane mimicking two-phase solution. Combined photothermal therapy and chemotherapy with the paclitaxel-loaded gold nanorods was shown to be highly effective in killing head and neck cancer cells and lung cancer cells, superior to photothermal therapy or chemotherapy alone due to a synergistic effect. The paclitaxel-gold nanorod enabled photothermal chemotherapy has the potential of preventing tumor reoccurrence and metastasis and may have an important impact on the treatment of head and neck cancer and other malignancies in the clinic

Size- and Shape-Controlled Synthesis and Properties of Magnetic–Plasmonic Core–Shell Nanoparticles

Magnetic–plasmonic core–shell nanomaterials offer a wide range of applications across science, engineering, and biomedical disciplines. However, the ability to synthesize and understand magnetic–plasmonic core–shell nanoparticles with tunable sizes and shapes remains very limited. This work reports experimental and computational studies on the synthesis and properties of iron oxide–gold core–shell nanoparticles of three different shapes (sphere, popcorn, and star) with controllable sizes (70 to 250 nm). The nanoparticles were synthesized via a seed-mediated growth method in which newly formed gold atoms were added onto gold-seeded iron oxide octahedrons to form a gold shell. The evolution of the shell into different shapes was found to occur after the coalescence of gold seeds, which was achieved by controlling the amount of additive (silver nitrate) and reducing agent (ascorbic acid) in the growth solution. First-principles calculation, together with experimental results, elucidated the intimate roles of thermodynamic and kinetic parameters in the shape-controlled synthesis. Both discrete dipole approximation calculation and experimental results showed that the nanopopcorns and nanostars exhibited red-shifted plasmon resonance compared with the nanospheres, with the nanostars giving multispectral feature. This research has made a great step further in manipulating and understanding magnetic–plasmonic hybrid nanostructures and will make an important impact in many different fields