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Bumpy Hollow Gold Nanospheres for Theranostic Application: Effect of Surface Morphology on Photothermal Conversion Efficiency
摘要： The combination of hollow core and rugose surface morphology is highly attractive for photoactive near-infrared (NIR) nanomaterials. Here, we present a facile pH modification to hollow gold nanosphere (HGN) synthesis to enable controlled tuning of the surface morphology from smooth to very bumpy. Unlike other methods, the synthetic protocol does not require harsh surfactants, secondary reducing agents, or organic solvents. The resultant bumpy HGNs (bHGNs) are highly monodisperse with little variation in protrusion length from particle to particle. Mechanistic studies suggest that surface rugosity is mainly controlled by the presence of free OH- ions in solution. We also present the first systematic investigation into the effect of surface morphology on the photothermal conversion efficiency (PCE) of bumpy as well as smooth HGNs, with a maximum PCE reaching 99%. Although expected to have a higher scattering component, the bHGNs retain the excellent PCE of their smooth counterparts, which may be due to efficient reabsorption of scattered light.
关键词： surface plasmon resonance,photothermal conversion efficiency,heat generation,surface morphology,hollow gold nanospheres
更新于2025-09-23 15:23:52
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Growth of Spherical Gold Satellites on the Surface of Au@Ag@SiO <sub/>2</sub> Core–Shell Nanostructures Used for an Ultrasensitive SERS Immunoassay of Alpha-Fetoprotein
摘要： The identification and detection of cancer biomarkers in early stages is an important issue for the therapy of cancer. However, most methods are time-consuming, limited sensing sensitivity and specificity. In this work, we prepared a novel plasmonic multilayered core–shell-satellite nanostructure (Au@Ag@SiO2-AuNP) consisting of an gold nanosphere with silver coating core (Au@Ag), an ultrathin continuous silica (SiO2) shell and high coverage of gold nanospheres (AuNPs) satellites. Au@Ag core is prominent surface enhanced Raman scattering (SERS) platform and the thin SiO2 layer exhibits a long-range plasmon coupling between Au@Ag core to AuNPs satellites further leading to enhanced Raman scattering. Meanwhile, the outer AuNPs satellites have a high biocompatibility and long-term stability. Combining the above advantages, the well-designed metallic nanoassemblies would be a promising candidate for SERS-based applications in biochemistry. For specific detection of alpha-fetoprotein (AFP), we utilized the SERS-active core-shell-satellite nanostructures modified with AFP antibody as immune probes and nitrocellulose membrane (NC) stabilized captured anti-AFP antibodies as solid substrate. To improve the detection performance, we further systematically optimized the parameters, including silver coating thickness of Au@Ag core, the density and size of satellite AuNPs. Under the optimized conditions, AFP could be detected by the SERS-based sandwich immunoassay with an ultralow detection limit of 0.3 fg/mL, and the method exhibited a wide linear response from 1 fg/mL to 1 ng/mL. The limit of detection (LOD) was considerably lower than conventional methods in literature. This work relies on the unique Au@Ag@SiO2-AuNP nanostructures as immune probe develops a new outlook for the application of multilayered nanoassemblies and demonstrates the great potential in early tumor markers detection.
关键词： surface enhanced Raman scattering (SERS),Au-Ag bimetallic nanospheres,alpha-fetoprotein,core-shell-satellite nanostructure,gold nanospheres
更新于2025-09-23 15:22:29
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[IEEE 2019 URSI International Symposium on Electromagnetic Theory (EMTS) - San Diego, CA, USA (2019.5.27-2019.5.31)] 2019 URSI International Symposium on Electromagnetic Theory (EMTS) - On the optimal plasmonic resonances in gold nanospheres embedded in dispersive media
摘要： New fundamental upper bounds have recently been given regarding the optimal plasmonic multipole resonances of a rotationally invariant sphere embedded in a lossy surrounding medium. The new theory is based on a generalized optical theorem for the absorption of a sphere in a lossy medium and employs straightforward analysis to explicitly maximize a concave function. The new bounds are briefly summarized in this paper and then employed in a study concerning the effectiveness of using gold nanospheres as absorbers of the sizes typically used in biomedical applications and plasmonic photothermal therapy.
关键词： plasmonic resonances,gold nanospheres,dispersive media,multipole absorption,photothermal therapy
更新于2025-09-16 10:30:52
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Effects of freezing on mesenchymal stem cells labeled with gold nanoparticles
摘要： Stem cell therapies are a promising treatment for many patients suffering from diseases with poor prognosis. However, clinical translation is inhibited by a lack of in vivo monitoring techniques to track stem cells throughout the course of treatment. Ultrasound-guided photoacoustic imaging of nanoparticle-labeled stem cells may be a solution. To allow photoacoustic tracking, stem cells must be labeled with an optically absorbing contrast agent. Gold nanoparticles are one option due to their cytocompatibility and strong optical absorption in the near-infrared region. However, stem cell labeling can require up to 24-hour incubation with nanoparticles in culture prior to use. Although stem cell monitoring is critically needed, the additional preparation time may not be feasible – it is cost prohibitive and stem cell treatments should be readily available in emergency situations as well as scheduled procedures. To remedy this, stem cells can be labeled prior to freezing and long-term storage. While it is well known that stem cells retain their cellular function after freezing, storage, and thawing, the impact of gold nanoparticles on this process has yet to be investigated. Therefore, we assessed the viability, multipotency, and photoacoustic activity of gold nanosphere-labeled mesenchymal stem cells after freezing, storage, and thawing for one week, one month, or two months and compared to unlabeled, na?ve mesenchymal stem cells which were frozen, stored, and thawed at the same time points. Results indicated no substantial change in viability as assessed by the MTT assay. Differentiation, observed through adipogenesis and osteogenesis, was also comparable to controls. Lastly, strong photoacoustic signals and similar photoacoustic spectral signatures remained. Further studies involving more diverse stem cell types and nanoparticles are required, but our data suggests that function and imaging properties of nanoparticle-labeled stem cells are maintained after freezing and storage, which improves translation of stem cell monitoring techniques by simplifying integration with clinical protocols.
关键词： photoacoustic imaging,cell tracking,freezing,Gold nanospheres,ultrasound,stem cells
更新于2025-09-16 10:30:52
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Scattering property of aqueous solution of CdTe quantum dots with gold nanoparticles
摘要： We prepared the aqueous solution of CdTe quantum dots with gold nanoparticles by chemical crystal growth method. We simulated the scattering property of aqueous solution of CdTe quantum dots with gold nanoparticles using Finite Difference Time Domain(FDTD) method and verified by absorption spectrophotometer. Compared with aqueous solution of CdTe quantum dots, it has stronger absorption and emission spectrum. And its scattering intensity is enhanced about 1.5 times than CdTe quantum dots. The result can be used widely in the medicine field and optical field.
关键词： Scattering,Gold nanospheres,FDTD,CdTe quantum dot
更新于2025-09-16 10:30:52
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Interferometric time- and energy-resolved photoemission electron microscopy for few-femtosecond nanoplasmonic dynamics
摘要： We report a time-resolved normal-incidence photoemission electron microscope with an imaging time-of-flight detector using ～7-fs near-infrared laser pulses and a phase-stabilized interferometer for studying ultrafast nanoplasmonic dynamics via nonlinear photoemission from metallic nanostructures. The interferometer’s stability (35 ± 6 as root-mean-square from 0.2 Hz to 40 kHz) as well as on-line characterization of the driving laser field, which is a requirement for nanoplasmonic near-field reconstruction, is discussed in detail. We observed strong field enhancement and few-femtosecond localized surface plasmon lifetimes at a monolayer of self-assembled gold nanospheres with ～40 nm diameter and ～2 nm interparticle distance. A wide range of plasmon resonance frequencies could be simultaneously detected in the time domain at different nanospheres, which are distinguishable already within the first optical cycle or as close as about ±1 fs around time-zero. Energy-resolved imaging (microspectroscopy) additionally revealed spectral broadening due to strong-field or space charge effects. These results provide a clear path toward visualizing optically excited nanoplasmonic near-fields at ultimate spatiotemporal resolution.
关键词： photoemission electron microscopy,nanoplasmonic dynamics,few-femtosecond,gold nanospheres,time-resolved
更新于2025-09-12 10:27:22