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Optimum normalized absorption cross-section vs. D p and λ for the Fe 3 O 4 @Au colloids (a). The surface plot and (b). the corresponding 2D projection of the surface plot.
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We study the optical response of monodisperse colloids of core-shell plasmonic nanoparticles and introduce a computational approach to optimize absorption for photothermal applications that require dilute colloids of non-interacting particles with a prescribed volume fraction. Since the volume fraction is held constant, the particle concentration i...
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Optical extinction is a handy and ubiquitous technique that allows us to study colloidal nanoparticles in their native state. The typical analysis of the extinction spectrum can be extended in order to obtain structural information of the sample such as the size distribution of the cores and the thickness of the coating layers. In this work the ext...
Citations
... Penelitian [53] menjelaskan bahwa bahan kimia berbasis gel silika-logam akan menyerap substrat. Asimilasi permukaan radikal alkoksil ke dalam koloid yang diberi pupuk logam Na akan mendekatkan substrat dan donor elektron. ...
... Analisis juga menunjukkan bahwa campuran SiO 2 /Au menunjukkan beberapa puncak absorbsi yang tajam dibandingkan dengan campuran Fe 3 O 4 /Au. Hal ini mungkin disebabkan oleh hilangnya inti Fe 3 O 4 yang berkontribusi secara signifikan terhadap absorbsi [53]. Perluasan SiO 2 pada permukaan air pada suhu rendah sangat dipercepat jika unsur O 2 di eksitasi [55]. ...
Air sebagai sumber kehidupan yang tak ternilai di bumi yang selalu digunakan setiap hari kini dihadapkan pada ancaman serius seperti polusi. Para peneliti dunia sedang mencari solusi inovatif untuk mengatasi masalah ini. Artikel ini menunjukkan tinjauan mengenai berbagai metode sintesis bahan Fe3O4, SiO2 dan TiO2 yang bertujuan untuk mengatasi polusi air. Dengan penerapan strategi seperti kopresipitasi, sol-gel dan hidrotermal, bahan-bahan tersebut berhasil membentuk nanopartikel berkualitas tinggi dengan ukuran dan distribusi yang dapat dikendalikan. Dari beberapa penelitian dan karakterisasi menunjukkan bahwa kombinasi Fe3O4/SiO2/TiO2 dapat digunakan sebagai katalis untuk mendegradasi zat polutan dalam air. Adapun beberapa indikator seperti pemilihan pelarut yang tepat, pengaturan suhu, tekanan, dan interval waktu yang cermat, merupakan kunci untuk mencapai langkah signifikan dalam mengatasi polusi air.
... Research [66] explained that the metal-silica gel chemical agent would absorb the substrate. The surface assimilation of alkoxyl radicals to colloid fertilized with Na metal will bring the substrate and negatron donor nearer. ...
... The analysis additionally showed that the SiO2@Au mixture showed several sharp absorption peaks from the Fe3O4 @Au mixture. It can be thanks to the loss of core Fe3O4, which contributes considerably to the absorption [66]. The expansion of SiO2 on the water's surface at low temperatures is greatly expedited if the O2 molecules area unit excited [68]. ...
The existence of water on earth is very abundant and has a vital role in the source of life for every living creature. In managing water resources, pollution is one of the issues world researchers face. This article reviews the characteristics and methods of synthesizing Fe2O3 and SiO2 materials to prevent water pollution. The strategies administrated antecedently square measure vapor deposition, microemulsion, solvothermal, coprecipitation, sol-gel, and hydrothermal. The formation of fine quality nanoparticles with controlled size associate degreed size distribution square measure typically achieved by selecting an applicable solvent mixture and varied parameters like temperature, pressure, and time interval.
... Five types of gold nanoparticles were synthesized and entered the preclinical testing phase, namely gold nanorods [11,12], gold nanospheres [13], gold nanoshells [14], gold nanocages [15,16] and gold nanostars [17,18]. These findings have stimulated numerous theoretical studies dedicated to the design of gold-based plasmonic nanoparticles that best meet the optimal requirements of the PTT technique and also at an affordable cost [19][20][21][22][23][24][25][26][27]. The dominant idea in these works is to design a hybrid nanostructure made up of gold and metallic, dielectric or magnetic material. ...
... A nanoparticle composed of gold and magnetic material is called a gold-based magnetoplasmonic nanoparticle. To our knowledge, the only structural models conceived for this kind of nanoparticles are of the core-magnetic/shell-plasmonic type cut in spherical, ellipsoidal and nanorod shapes [25][26][27]. ...
The absorption and scattering efficiencies of light by a single magnetoplasmonic nanoparticle, based on magnetite and gold, embedded in human tissue are analyzed theoretically in the framework of Finite-Difference-Time-Domain method and Lorenz-Mie theory. We consider separately three different architectures for the magnetoplasmonic nanoparticle: rectangular three-layer gold/magnetite/gold nanobar, circular three-layer gold/magnetite/gold nanoring and magnetite/gold core/shell nanosphere. We address the influence of particle sizes and magnetite-layer and gold-layer thicknesses on the optical response of such nanostructures. Particular attention is paid to the effectiveness of these designed nanostructures in photothermal therapy. Our simulation shows that these hybrid nanostructures support the famous localized surface plasmon resonance mode of gold, which manifests itself in the absorption spectrum by an intense peak whose spectral position can be adjusted to be in the first and second NIR-biological windows. The magnitude of the resonant absorption peak as well as that of the corresponding scattering peak vary from one nanostructure to another and, for the same nanostructure, change with its characteristic sizes. The three-layer nanobars as well as the three-layer nanorings can support significant absorption accompanied by significant scattering of light into both NIR-biological windows. For core/shell nanospheres, the low scattering efficiency of light within the second NIR-biological window, together with their large sizes, limit the usefulness of these nanostructures in photothermal therapy operating in the first NIR-biological window only.
... Cloaking, Kerker effect [109], super-or optimally tuned scattering [51,[110][111][112][113][114][115] and absorption [20,51,113,[115][116][117][118], embedded photonic eigenvalues [119], spasing [44,47,120,121] and other intriguing phenomena [122] are easily understood from fundamental cross sections (19) and scattering patterns (20). We have summarized a self-consistent and comprehensive RTMM theory reported earlier in our [68,70] for electromagnetic light scattering from general multilayered spheres composed of isotropic shells. ...
We present a computer code for calculating near- and far-field electromagnetic properties of multilayered spheres. STRATIFY is one-of-a-kind open-source package which allows for the efficient calculation of electromagnetic near-field, energy density, total electromagnetic energy, radiative and non-radiative decay rates of a dipole emitter located in any (non-absorbing) shell (including a host medium), and fundamental cross-sections of a multilayered sphere, all within a single program. The developed software is typically more than 50 times faster than freely available packages based on boundary-element-method. Because of its speed and broad applicability, our package is a valuable tool for analysis of numerous light scattering problems, including, but not limited to fluorescence enhancement, upconversion, downconversion, second harmonic generation, surface enhanced Raman spectroscopy. The software is available for download from GitLab https://gitlab.com/iliarasskazov/stratify
... The monodispersed gold nanoparticles were used as labels to increase the sensitivity of the SPR imaging technique [10]. The amplification effect of antibody gold nanoparticles (AuNPs) and aptamer-AuNPs on the detection by SPR, and the development of a sandwich SPR method for protein detection, had been verified in previous research [2,3,[11][12][13][14]. ...
C-reactive protein (CRP) plays an important role in inflammation detection and disease monitoring. The optical biosensor is a highly sensitive and easy detection tool. The microfluidic self-driving optical sensors were fabricated with transparent glass material and used for the enhanced surface plasmon resonance (SPR) optical detection of the model protein CRP using Au nanoparticles (AuNPs) and a sandwich immune reaction. The 3D design of the chip was devised to improve the optical coupling efficiency and enable integration with a microfluidic control and rapid detection. The array of pre-fixed antibody modified by Au nanoparticles was used to achieve rapid antigen capture and improve the optical sensitivity. The Au nanoparticle amplification approach was introduced for the SPR detection of a target protein. CRP was used as a model target protein as part of a sandwich assay. The use of Au NP measurements to detect the target signal is a threefold improvement compared to single SPR detection methods.
... Here, to increase the NPR shift, dielectric core-Ag shell NPs are utilized and placed on a substrate with high refractive index such as silicon. By employing Mie theory calculations, it is shown that plasmon resonance wavelength of dielectric core-metal shell NPs shift toward longer wavelengths by increasing the relative core diameter [39]. Hence, it is expected that NPR also experiences such a red shift by increasing D c /D p . ...
In this article, plasmonic characteristics of SiO 2 -Ag and hollow core Ag nanoparticles placed on dielectric substrates are investigated and tuned to the NIR wavelength spectrum for biological applications. It is shown that by placing the core-shell Ag nanoparticles on a dielectric substrate and exciting the normal plasmon mode of the nanoparticle, it is possible to obtain strong plasmon resonances at wavelengths as long as λ = 700 nm which exhibits a red shift of more than 300 nm compared to the resonance of freestanding pure Ag nanoparticles at which normal plasmon resonance wavelength shows a sensitivity of approximately 100 nm/RIU in respect to the substrate refractive index change. “SiO 2 -Ag and hollow core Ag nanoparticles on silicon” are optimized to exhibit a strong normal plasmon resonance at λ = 633 nm while preserving the plasmonic field enhancement intact. Finally, a three dimensional substrate for surface-enhanced Raman spectroscopy (SERS) is designed and numerically investigated. The substrate is composed of Si nanorod array decorated with the designed nanoparticles which exhibits superior characteristics such as a uniform and gapless field enhancement and an electromagnetic enhancement factor of more than 3 × 10 ⁶ , an order of magnitude higher than the enhancement factor for a similar structure decorated with Au nanoparticles.
... In this study, we have chosen magnetite as the oxide core candidate, since it offers properties like magnetic recoverability in catalysis, magnetic hyperthermia, magnetoplasmonic etc [26][27][28][29][30][31] . In case of metal shells, gold has been chosen for its well-known plasmonic 32 , catalytic and biological applications, whilst silver has been chosen due to its dominant plasmonic and anti-microbial properties [33][34][35][36][37][38][39] . We hypothesized that coating a noble metal-containing surfactant-based precursor over an oxide core as a thin film followed by metalization would result in a continuous metal shell formation. ...
Solvent-less synthesis of nanostructures is highly significant due to its economical, eco-friendly and industrially viable nature. Here we report a solid state synthetic approach for the fabrication of Fe3O4@M (where M = Au, Ag and Au-Ag alloy) core-shell nanostructures in nearly quantitative yields that involves a simple physical grinding of a metal precursor over Fe3O4 core, followed by calcination. The process involves smooth coating of low melting hybrid organic-inorganic precursor over the Fe3O4 core, which in turn facilitates a continuous shell layer post thermolysis. The obtained core-shell nanostructures are characterized using, XRD, XPS, ED-XRF, FE-SEM and HR-TEM for their phase, chemical state, elemental composition, surface morphology, and shell thickness, respectively. Homogeneous and continuous coating of the metal shell layer over a large area of the sample is ascertained by SAXS and STEM analyses. The synthesized catalysts have been studied for their applicability towards a model catalytic hydrogen generation from NH3BH3 and NaBH4 as hydrogen sources. The catalytic efficacy of the Fe3O4@Ag and Ag rich alloy shell materials are found to be superior to the corresponding Au counterparts. The saturation magnetization studies reveal the potential of the core-shell nanostructured catalysts to be magnetically recoverable and recyclable.
... The synthesis of rod-shape Fe3O4-Au heterodimers for bioapplications was reported in several works [101,[163][164][165][166]. Fe3O4-Pt heterodimers of rod-shape as well as core-shell morphologies were fabricated using Pt seeds and they exhibited significantly enhanced plasmonic properties for photothermal therapy when compared to their single components [167]. ...
... The synthesis of rod-shape Fe 3 O 4 -Au heterodimers for bioapplications was reported in several works [101,[163][164][165][166]. Fe 3 O 4 -Pt heterodimers of rod-shape as well as core-shell morphologies were fabricated using Pt seeds and they exhibited significantly enhanced plasmonic properties for photothermal therapy when compared to their single components [167]. ...
Magnetic-plasmonic heterodimer nanostructures synergistically present excellent magnetic and plasmonic characteristics in a unique platform as a multipurpose medium for recently invented biomedical applications, such as magnetic hyperthermia, photothermal therapy, drug delivery, bioimaging, and biosensing. In this review, we briefly outline the less-known aspects of heterodimers, including electronic composition, interfacial morphology, critical properties, and present concrete examples of recent progress in synthesis and applications. With a focus on emerging features and performance of heterodimers in biomedical applications, this review provides a comprehensive perspective of novel achievements and suggests a fruitful framework for future research.
... Applying Mie theory, the optical spectra of such hetero-structures were calculated for two different particle sizes, 60 and 100 nm, and various ratios between the shell thickness and the core radius, 10%, 20%, 30%, and 40%. The obtained spectra showed that the plasmonic absorption band is red-shifted as the ratio decreased [87]. This feature was confirmed experimentally by Canet-Ferrer et al. [88], who evidenced that the extinction spectra of Fe3O4-Au coreshell NSs of 5 nm in diameter, exhibited the highest absorption wavelength (around 700 nm) when the gold thickness was the thinnest (about 1 nm). ...
... Applying Mie theory, the optical spectra of such hetero-structures were calculated for two different particle sizes, 60 and 100 nm, and various ratios between the shell thickness and the core radius, 10%, 20%, 30%, and 40%. The obtained spectra showed that the plasmonic absorption band is red-shifted as the ratio decreased [87]. This feature was confirmed experimentally by Canet-Ferrer et al. [88], who evidenced that the extinction spectra of Fe 3 O 4 -Au core-shell NSs of 5 nm in diameter, exhibited the highest absorption wavelength (around 700 nm) when the gold thickness was the thinnest (about 1 nm). ...
... Parametric analysis of optimum normalized absorption vs. λ for two different sized Fe 3 O 4 @Au NPS with various shell-to-radius ratios ξ Au (a) D p = 60 nm, (b) D p = 100 nm. Reproduced with permission from[87]. ...
Iron oxide and gold-based magneto-plasmonic nanostructures exhibit remarkable optical and superparamagnetic properties originating from their two different components. As a consequence, they have improved and broadened the application potential of nanomaterials in medicine. They can be used as multifunctional nanoprobes for magneto-plasmonic heating as well as for magnetic and optical imaging. They can also be used for magnetically assisted optical biosensing, to detect extreme traces of targeted bioanalytes. This review introduces the previous work on magneto-plasmonic hetero-nanostructures including: (i) their synthesis from simple “one-step” to complex “multi-step” routes, including seed-mediated and non-seed-mediated methods; and (ii) the characterization of their multifunctional features, with a special emphasis on the relationships between their synthesis conditions, their structures and their properties. It also focuses on the most important progress made with regard to their use in nanomedicine, keeping in mind the same aim, the correlation between their morphology—namely spherical and non-spherical, core-satellite and core-shell, and the desired applications.
... Also note, that for larger tuning capabilities, NPs with cores ranging between D C = 4-100 nm and shells up to 40 nm can also be prepared. [27][28][29][30][31] For the case of the dumbbell, Fe(Au) composites have been synthesised with minor modifications on the procedures of ref. 32. The synthesis begins with the growth of Fe 3 O 4 NPs but in this case, the gold precursor is injected before all the iron oxide precursor in the solution runs out. ...
Hybrid systems based on magnetite and gold nanoparticles have
been extensively used as bifunctional materials for bio- and nano-
technology. The properties of these composites are assumed to be
closely related to the magnetite to gold mass ratio and to the
geometry of the resulting hetero-structures. To illustrate this, we
compare and analyze the optical and magnetic properties of core–
shell, dumbbell-like dimers and chemical cross-linked pairs of
magnetite and gold nanoparticles in detail. We explore how the
combination of gold with magnetite can lead to an improvement of
the optical properties of these systems, such as tunability, light
scattering enhancement or an increase of the local electric field at
the interface between magnetic and plasmonic constituents. We
also show that although the presence of gold might affect the
magnetic response of these hybrid systems, they still show good
performance for magnetic applications; indeed the resulting
magnetic properties are more dependent on the NP size dispersion.
Finally, we identify technological constraints and discuss prospec-
tive routes for the development of further magnetic–plasmonic
materials.
