nanoschalen

Nanoschalen are nanoscale core–shell particles composed of a dielectric core encased in a thin metallic shell, most commonly gold. This architecture produces a strong localized surface plasmon resonance whose position depends on core size and shell thickness. By tuning these dimensions, the resonance can be shifted into the near-infrared window, where biological tissue is relatively transparent.

Synthesis is typically performed in two steps. A dielectric core such as silica is made first, then coated with a thin gold shell via seed-mediated growth. Small gold nanoparticles are attached to the core surface and chemically reduced gold is deposited to form a continuous shell. Variants use alternative cores (such as polystyrene) or different reduction chemistries. Particle sizes generally range from tens to a few hundred nanometers with shell thickness on the order of a few to several tens of nanometers.

Properties include a strong absorption and scattering cross-section due to the gold shell, enabling imaging modalities such as photoacoustic imaging and efficient photothermal conversion for therapy. The shell surface can be functionalized with polyethylene glycol (PEG), antibodies, aptamers, or drugs to improve stability, targeting, and delivery capabilities.

Applications are primarily biomedical, including photothermal therapy for cancer, targeted imaging and contrast enhancement, and theranostic platforms that combine diagnostic and therapeutic functions. The core can be engineered to carry additional functionalities, and the shell allows surface conjugation of therapeutic payloads.

Safety and challenges involve biocompatibility with appropriate coatings, but biodistribution, clearance, and long-term effects are active research areas. Reproducible synthesis and controlled aggregation remain important technical considerations.