Thermal Stability and Hot Carrier Dynamics of Gold Nanoparticles of Different Shapes

Attia, Yasser A.; Altalhi, Tariq; Gobouri, Adil A.

doi:10.4236/anp.2015.44010

Cited by 12 publications

(15 citation statements)

References 44 publications

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“…To enhance coupling, several strategies can be applied, such as (i) the use of larger AuNPs , or (ii) other AuNP shapes − or by (iii) varying the thickness of the gold fiber coating . Notably, the first strategy provides only limited tunability of the resonance wavelength of the AuNPs (∼10 s of nms), whereas there is no straightforward relation between the shape and resonance wavelength of AuNPs.…”

Section: Resultsmentioning

confidence: 99%

Integrated Signal Amplification on a Fiber Optic SPR Sensor Using Duplexed Aptamers

et al. 2023

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Throughout the past decades, fiber optic surface plasmon resonance (FO-SPR)-based biosensors have proven to be powerful tools for both the characterization of biomolecular interactions and target detection. However, as FO-SPR signals are generally related to the mass that binds to the sensor surface, multistep processes and external reagents are often required to obtain significant signals for low molecular weight targets. This increases the time, cost, and complexity of the respective bioassays and hinders continuous measurements. To overcome these requirements, in this work, cis-duplexed aptamers (DAs) were implemented on FO-SPR sensors, which underwent a conformational change upon target binding. This induced a spatial redistribution of gold nanoparticles (AuNPs) upon specific target binding and resulted in an amplified and concentrationdependent signal. Importantly, the AuNPs were covalently conjugated to the sensor, so the principle does not rely on multistep processes or external reagents. To implement this concept, first, the thickness of the gold fiber coating was adapted to match the resonance conditions of the surface plasmons present on the FO-SPR sensors with those on the AuNPs. As a result, the signal obtained due to the spatial redistribution of the AuNPs was amplified by a factor of 3 compared to the most commonly used thickness. Subsequently, the cis-DAs were successfully implemented on the FO-SPR sensors, and it was demonstrated that the DA-based FO-SPR sensors could specifically and quantitatively detect an ssDNA target with a detection limit of 230 nM. Furthermore, the redistribution of the AuNPs was proven to be reversible, which is an important prerequisite for continuous measurements. Altogether, the established DA-based FO-SPR bioassay holds much promise for the detection of low molecular weight targets in the future and opens up possibilities for FO-SPRbased continuous biosensing.

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Section: Resultsmentioning

confidence: 99%

Integrated Signal Amplification on a Fiber Optic SPR Sensor Using Duplexed Aptamers

et al. 2023

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“…[7,8,11,[14][15][16][17][18] However, the thermal stability of Au NPs is inversely proportional to their aspect ratio. [19][20][21] As a result, anisotropic Au NPs with high aspect ratios are prone to photodamage from high-intensity laser pulses used in PA imaging, often exceeding 10 mJ cm −2 , which causes rapid structural changes into spheres via surface diffusion of Au atoms to minimize surface energy. [21][22][23] This structural deformation results in decreased optical absorption and decay of PA signals in the NIR window, [8,15,22] making anisotropic Au NPs unsuitable for reliable PA imaging under repetitive laser pulses and over multiple imaging sessions.…”

Section: Introductionmentioning

confidence: 99%

Tunable Interparticle Connectivity in Gold Nanosphere Assemblies for Efficient Photoacoustic Conversion

Kim,

VanderLaan

et al. 2023

Adv Funct Materials

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Manipulating matter at the nanometer scale to create desired plasmonic nanostructures holds great promise in the field of biomedical photoacoustic (PA) imaging. This study demonstrates a strategy for regulating PA signal generation from anisotropic nanosized assemblies of gold nanospheres (Au NSs) by adjusting the interparticle connectivity between neighboring Au NSs. The interparticle connectivity is controlled by modulating the diameter and interparticle spacing of Au NSs in the nanoassemblies. The results indicate that nanoassemblies with semi‐connectivity, i.e., assemblies with a finite interparticle spacing shorter than the theoretical limit of repulsion between nearby Au NSs, exhibit 3.4‐fold and 2.4‐fold higher PA signals compared to nanoassemblies with no connectivity and full connectivity, respectively. Furthermore, due to the reduced diffusion of Au atoms, the semi‐connectivity Au nanoassemblies demonstrates a high photodamage threshold and, therefore, excellent photostability at fluences above the current American National Standards Institute limits. The exceptional photostability of the semi‐connectivity nanoassemblies highlights their potential to surpass conventional plasmonic contrast agents for continuing PA imaging. Collectively, the findings indicate that semi‐connected nanostructures are a promising option for reliable, high‐contrast PA imaging applications over multiple imaging sessions due to their strong PA signals and enhanced photostability.

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“…Because of the limited phototransduction efficiency of some of the existing nanomaterials, they require high-intensity laser irradiation with repeated exposure to produce an effective thermal ablation temperature. 6 This constant exposure to high laser power irradiation often results in the loss of surface functionalities of plasmonic nanoparticles, leading to poor thermal stability. Furthermore, it also exceeds the threshold value of the human skin's tolerance for the laser, thereby increasing toxicity.…”

Section: Introductionmentioning

confidence: 99%

“…However, the NIR-II region is more favorable for executing photothermal therapy because of its higher penetration depth into tissues and reduced scattering. − Additionally, some of the existing nanostructures exhibit poor thermal stability at high temperatures. Because of the limited phototransduction efficiency of some of the existing nanomaterials, they require high-intensity laser irradiation with repeated exposure to produce an effective thermal ablation temperature . This constant exposure to high laser power irradiation often results in the loss of surface functionalities of plasmonic nanoparticles, leading to poor thermal stability.…”

Section: Introductionmentioning

confidence: 99%

Palladium Nanocapsules for Photothermal Therapy in the Near-Infrared II Biological Window

Singh,

Haloi,

Singh

et al. 2023

ACS Appl. Mater. Interfaces

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Recent developments in nanomaterials with programmable optical responses and their capacity to modulate the photothermal effect induced by an extrinsic source of light have elevated plasmonic photothermal therapy (PPTT) to the status of a favored treatment for a variety of malignancies. However, the low penetration depth of nearinfrared-I (NIR-I) lights and the need to expose the human body to a high laser power density in PPTT have restricted its clinical translation for cancer therapy. Most nanostructures reported to date exhibit limited performance due to (i) activity only in the NIR-I region, (ii) the use of intense laser, (iii) need of large concentration of nanomaterials, or (iv) prolonged exposure times to achieve the optimal hyperthermia state for cancer phototherapy. To overcome these shortcomings in plasmonic nanomaterials, we report a bimetallic palladium nanocapsule (Pd Ncap)�with a solid gold bead as its core and a thin, perforated palladium shell�with extinction both in the NIR-I as well as the NIR-II region for PPTT applications toward cancer therapy. The Pd Ncap demonstrated exceptional photothermal stability with a photothermal conversion efficiency of ∼49% at the NIR-II (1064 nm) wavelength region at a very low laser power density of 0.5 W/cm 2 . The nanocapsules were further surfacefunctionalized with Herceptin (Pd Ncap-Her) to target the breast cancer cell line SK-BR-3 and exploited for in vitro PPTT applications using NIR-II light. Pd Ncap-Her caused more than 98% cell death at a concentration of just 50 μg/mL and a laser power density of 0.5 W/cm 2 with an output power of only 100 mW. Flow cytometric and microscopic analyses revealed that Pd Ncap-Herinduced apoptosis in the treated cancer cells during PPTT. Additionally, Pd Ncaps were found to have reactive oxygen species (ROS) scavenging ability, which can potentially reduce the damage to cells or tissues from ROS produced during PPTT. Also, Pd Ncap demonstrated excellent in vivo biocompatibility and was highly efficient in photothermally ablating tumors in mice. With a high photothermal conversion and killing efficiency at very low nanoparticle concentrations and laser power densities, the current nanostructure can operate as an effective phototherapeutic agent for the treatment of different cancers with ROS-protecting ability.

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Thermal Stability and Hot Carrier Dynamics of Gold Nanoparticles of Different Shapes

Cited by 12 publications

References 44 publications

Integrated Signal Amplification on a Fiber Optic SPR Sensor Using Duplexed Aptamers

Integrated Signal Amplification on a Fiber Optic SPR Sensor Using Duplexed Aptamers

Tunable Interparticle Connectivity in Gold Nanosphere Assemblies for Efficient Photoacoustic Conversion

Palladium Nanocapsules for Photothermal Therapy in the Near-Infrared II Biological Window

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