Optical Characterization of Anisotropic Nanoparticles

Anisotropic nanoparticles, characterised by non-spherical shapes such as rods, bipyramids or platelets, display direction-dependent optical responses that underpin applications in sensing, biomedical imaging and nanophotonic devices. Their optical characterisation encompasses interrogation of surface plasmon resonances, polarisation-dependent scattering and absorption spectra, and dynamic measurements of translational and rotational diffusion. Techniques such as dark-field microscopy, polarimetric spectroscopy and modulated light-scattering enable determination of aspect ratio, orientation and dipolar modes at the single-particle level. Recent advances have extended these methods to live-cell environments and turbid media, yielding detailed insight into intracellular transport, receptor binding and shape-dependent functionalisation. The combination of high spatial and temporal resolution with non-invasive optical probes positions this field at the intersection of fundamental nanoscience and practical applications in diagnostics, therapeutics and materials design.

Research from Nature Portfolio

Automated five-dimensional tracking has been developed to resolve both translational and rotational motions of gold nanorods inside live cells. By combining differential interference contrast microscopy with advanced image analysis, researchers have mapped three spatial coordinates together with azimuthal and elevation angles of endocytic nanorods, revealing characteristic rotational diffusion phases during membrane internalisation and transport. In parallel, temporally-modulated polarisation strategies have been used to enhance contrast and achieve super-resolution imaging of non-spherical nanoparticles in apoptotic and live cells. Modulating the incident polarisation and applying lock-in amplification principles allows the extraction of orientation information beneath the diffraction limit, improving both sensitivity and spatial resolution in complex biological environments.

Optical Characterization of Anisotropic Nanoparticles publication trend

The graph below shows the total number of articles in optical characterization of anisotropic nanoparticles across all publications each year (not limited to Nature Index journals).

Technical terms

Anisotropic Nanoparticles: Nanostructures whose optical or physical properties vary with direction due to non-spherical shape.

Surface Plasmon Resonance (SPR): Collective oscillation of conduction electrons in metal nanoparticles induced by light, sensitive to particle geometry and environment.

Polarisation Anisotropy: Variation in scattering or absorption intensity when the polarisation of incident light is rotated, used to infer particle orientation.

Dynamic Light Scattering (DLS): Technique measuring time-dependent fluctuations in scattered light to determine hydrodynamic size and diffusion coefficients.

Rotational Diffusion: Random rotational motion of particles in fluid, governed by thermal energy and particle geometry, distinct from translational diffusion.

References

1. Dipole Determination by Polarimetric Spectroscopy Yielding the Orientation of Gold Nanorods. Small Science (2025).
2. Single-Shot Aspect Ratio and Orientation Imaging of Nanoparticles. ACS Photonics (2023).
3. Real-time six-dimensional spatiotemporal tracking of single anisotropic nanoparticles in live cells by integrated multifunctional light-sheet nanoscopy. Microchimica Acta (2023).
4. Characteristic rotational behaviors of rod-shaped cargo revealed by automated five-dimensional single particle tracking. Nature Communications (2017).
5. Single-Shot Three-Dimensional Orientation Imaging of Nanorods Using Spin to Orbital Angular Momentum Conversion. Nano Letters (2021).
6. Imaging of nanoparticle dynamics in live and apoptotic cells using temporally-modulated polarization. Scientific Reports (2019).