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Differential photothermal and photodynamic performance behaviors of gold nanorods, nanoshells and nanocages under identical energy conditions
摘要： Various gold (Au) nanostructures have shown promising near infrared (NIR) light-activated phototherapeutic effects; however, their reported photothermal or photodynamic performance behavior is usually inconsistent or even conflicted, dramatically limiting the improvement of phototherapeutic Au nanostructures. The potential reason for this uncertainty is mainly because the photoactivities of Au nanostructures are not evaluated under identical energy conditions. Herein, three Au nanostructures, Au nanorods (NRs), nanoshells (NSs), and nanocages (NCs), were prepared to provide the same localized surface plasmon resonance (LSPR) peaks at 808 nm. All these Au nanostructures (at the same optical density) could fully exert their photoactivities under the identical and optimal energy condition of 808 nm laser irradiation. It was found that these Au nanostructures could induce similar levels of temperature elevation but different levels of reactive oxygen species (ROS) production, where Au NCs exhibited the highest ROS production, followed by Au NSs and NRs. In vitro and in vivo phototherapeutic assessments further supported that Au NCs could cause the most severe cell death and tumor growth regression. This means that the identical incident energy has different contribution to photothermal and photodynamic performance of Au nanostructures, and the corner angle structures of Au NCs compared with NSs and NCs could more efficiently convert the photon energy into photodynamic property. Taken all together, Au NCs hold great potential for phototherapy due to their efficient energy utilization capability.
关键词： reactive oxygen species,photodynamic therapy,gold nanostructures,photothermal therapy,cancer treatment
更新于2025-11-21 11:08:12
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Orientation Effects on Plasmonic Heating of Near-Infrared Colloidal Gold Nanostructures
摘要： Photothermal therapy assisted by plasmonic nanostructure relies on the absorption of light energy by the metallic nanoparticle. The manifestation of a rational use of plasmonic-assisted superficial laser thermal therapy procedures requires the analyses of the thermoplasmonic behavior of colloidal nanostructures in random orientation. A quantitative analysis of orientation effect on optically heating metallic nanostructures still unrevealed. Here, we evaluate the thermal properties of metallic nanoparticles (SiO2/Au core-shell particles, Au nanotriangles, Au nanorods, and Au nanocages) irradiated by polarized light. We perform 3D full-wave field analysis to compare absorption properties and temperature rise of these nanoparticles as a function of the nanostructure orientation with respect to applied field polarization. The analysis shows a major variation in joule number of asymmetrical nanostructures (up to 50%) due to orientation effects, which may limit its performance on colloidal photothermal applications. In contrast, the high degree of rotational symmetry of core-shell nanoparticles and nanocages provide greater potential in thermal-assisted phototherapy applications, as their absorption is largely independent (less than 2%) of their orientation in colloid. Our computational results establish new insights for the use of gold nanocages, as a high performance plasmonic structure for thermal applications with colloidal samples.
关键词： Joule number,Photothermal therapy,Gold nanostructures,Thermo-plasmonics
更新于2025-09-23 15:21:01
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Plasmonic-Active Nanostructured Thin Films
摘要： Plasmonic-active nanomaterials are of high interest to scientists because of their expanding applications in the field for medicine and energy. Chemical and biological sensors based on plasmonic nanomaterials are well-established and commercially available, but the role of plasmonic nanomaterials on photothermal therapeutics, solar cells, super-resolution imaging, organic synthesis, etc. is still emerging. The effectiveness of the plasmonic materials on these technologies depends on their stability and sensitivity. Preparing plasmonics-active nanostructured thin films (PANTFs) on a solid substrate improves their physical stability. More importantly, the surface plasmons of thin film and that of nanostructures can couple in PANTFs enhancing the sensitivity. A PANTF can be used as a transducer for any of the three plasmonic-based sensing techniques, namely, the propagating surface plasmon, localized surface plasmon resonance, and surface-enhanced Raman spectroscopy-based sensing techniques. Additionally, continuous nanostructured metal films have an advantage for implementing electrical controls such as simultaneous sensing using both plasmonic and electrochemical techniques. Although research and development on PANTFs have been rapidly advancing, very few reviews on synthetic methods have been published. In this review, we provide some fundamental and practical aspects of plasmonics along with the recent advances in PANTFs synthesis, focusing on the advantages and shortcomings of the fabrication techniques. We also provide an overview of different types of PANTFs and their sensitivity for biosensing.
关键词： localized surface plasmon resonance (LSPR),plasmonics,gold nanostructures,biosensing,thin film,lithography,nanohole array,nanofabrication
更新于2025-09-19 17:13:59
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Nonlinear absorption and scattering of a single plasmonic nanostructure characterized by <i>x</i> -scan technique
摘要： Nonlinear nanoplasmonics is a largely unexplored research area that paves the way for many exciting applications, such as nanolasers, nanoantennas, and nanomodulators. In the field of nonlinear nanoplasmonics, it is highly desirable to characterize the nonlinearity of the optical absorption and scattering of single nanostructures. Currently, the common method to quantify optical nonlinearity is the z-scan technique, which yields real and imaginary parts of the permittivity by moving a thin sample with a laser beam. However, z-scan typically works with thin films, and thus acquires nonlinear responses from ensembles of nanostructures, not from single ones. In this work, we present an x-scan technique that is based on a confocal laser scanning microscope equipped with forward and backward detectors. The two-channel detection offers the simultaneous quantification for the nonlinear behavior of scattering, absorption and total attenuation by a single nanostructure. At low excitation intensities, both scattering and absorption responses are linear, thus confirming the linearity of the detection system. At high excitation intensities, we found that the nonlinear response can be derived directly from the point spread function of the x-scan images. Exceptionally large nonlinearities of both scattering and absorption are unraveled simultaneously for the first time. The present study not only provides a novel method for characterizing nonlinearity of a single nanostructure, but also reports surprisingly large plasmonic nonlinearities.
关键词： nonlinear absorption,absorption cross section,nonlinear scattering,single gold nanostructures,laser scanning microscopy,nanoplasmonics
更新于2025-09-16 10:30:52