Responsive Plasmonic Nanomaterials for Advanced Cancer Diagnostics

Abstract

Plasmonic nanostructures, particularly of noble-metal Au and Ag, have attracted long-lasting research interests because of their intriguing physical and chemical properties. Under light excitation, their conduction electrons can form collective oscillation with the electromagnetic fields at particular wavelength, leading to localized surface plasmon resonance (LSPR). The remarkable characteristic of LSPR is the absorption and scattering of light at the resonant wavelength and greatly enhanced electric fields in localized areas. In response to the chemical and physical changes, these optical properties of plasmonic nanostructures will exhibit drastic color changes and highly sensitive peak shifts, which has been extensively used for biological imaging and disease treatments. In this mini review, we aim to briefly summarize recent progress of preparing responsive plasmonic nanostructures for biodiagnostics, with specific focus on cancer imaging and treatment. We start with typical synthetic approaches to various plasmonic nanostructures and elucidate practical strategies and working mechanism in tuning their LSPR properties. Current achievements in using responsive plasmonic nanostructures for advanced cancer diagnostics will be further discussed. Concise perspectives on existing challenges in developing plasmonic platforms for clinic diagnostics is also provided at the end of this review.

Design Strategy for Nanostructured Arrays of Metallodielectric Cuboids to Systematically Tune the Optical Response and Eliminate Spurious Bulk Effects in Plasmonic Biosensors

“…To reduce the effort and costs for the production of the devices, replication from a master structure [ 41 ] will probably be the most effective approach, e.g., by molding procedures [ 42 ]. The option of signal control [ 4 , 38 , 43 , 44 ] and biofunctionalization make plasmonic platforms a powerful tool in the field of clinical studies [ 43 , 45 ].…”

Magnetic Metal Oxide-Based Photocatalysts with Integrated Silver for Water Treatment

“…Another area in which the magnetic substrate can manipulate the integrated plasmonic nanostructures is in their orientational control, thereby allowing for the tuning of the LSPR peak intensity [59]. Plasmonic-magnetic nanocomposites that are responsive to magnetic forces offer a remote and reversible way to control anisotropically shaped plasmonic nanostructures (e.g., nanorods) under external magnetic fields.…”

“…The position of the energy levels of the semiconductor relative to the silver redox potential defines the number and significance of active photocatalytic enhancement mechanisms, making the choice of the magnetic component very important and often requiring additional SC components for proper energy-level engineering (e.g., ternary composites). Another area in which the magnetic substrate can manipulate the integrated plasmonic nanostructures is in their orientational control, thereby allowing for the tuning of the LSPR peak intensity [59]. Plasmonic-magnetic nanocomposites that are responsive to magnetic forces offer a remote and reversible way to control anisotropically shaped plasmonic nanostructures (e.g., nanorods) under external magnetic fields.…”

“…Beyond the magnetic separation capability, there is a great untapped potential regarding the utilization of other magnetic-based capabilities of magnetic silver-integrated composites for photocatalytic water purification applications, though such composites offer an array of useful properties as discussed above. Especially interesting are the effects of tuning the plasmonic characteristics of these composites, such as the function of the remote and reversible orientational control (through the use of a magnetic field) for controlling the LSPR peak intensity of plasmon structures on magnetic substrates, which has been utilized in cancer diagnosis [59]. Another even more fascinating result that has been recently reported in Au-decorated Fe 2 O 3 -TiO 2 nanotubular structures is the anisotropic magnetic-field-induced tuning of the photocatalytic activity [161].…”