Plasmonic nanoparticles

Last updated June 26, 2024

FDTD simulation of a pulsed plane wave interaction with plasmonic nanoparticles^[1]

Plasmonic nanoparticles are particles whose electron density can couple with electromagnetic radiation of wavelengths that are far larger than the particle due to the nature of the dielectric-metal interface between the medium and the particles: unlike in a pure metal where there is a maximum limit on what size wavelength can be effectively coupled based on the material size.^[2]

What differentiates these particles from normal surface plasmons is that plasmonic nanoparticles also exhibit interesting scattering, absorbance, and coupling properties based on their geometries and relative positions.^[3]^[4] These unique properties have made them a focus of research in many applications including solar cells, spectroscopy, signal enhancement for imaging, and cancer treatment.^[5]^[6] Their high sensitivity also identifies them as good candidates for designing mechano-optical instrumentation.^[7]

Plasmons are the oscillations of free electrons that are the consequence of the formation of a dipole in the material due to electromagnetic waves. The electrons migrate in the material to restore its initial state; however, the light waves oscillate, leading to a constant shift in the dipole that forces the electrons to oscillate at the same frequency as the light. This coupling only occurs when the frequency of the light is equal to or less than the plasma frequency and is greatest at the plasma frequency that is therefore called the resonant frequency. The scattering and absorbance cross-sections describe the intensity of a given frequency to be scattered or absorbed. Many fabrication processes or chemical synthesis methods exist for preparation of such nanoparticles, depending on the desired size and geometry.

The nanoparticles can form clusters (the so-called "plasmonic molecules") and interact with each other to form cluster states. The symmetry of the nanoparticles and the distribution of the electrons within them can affect a type of bonding or antibonding character between the nanoparticles similarly to molecular orbitals. Since light couples with the electrons, polarized light can be used to control the distribution of the electrons and alter the mulliken term symbol for the irreducible representation. Changing the geometry of the nanoparticles can be used to manipulate the optical activity and properties of the system, but so can the polarized light by lowering the symmetry of the conductive electrons inside the particles and changing the dipole moment of the cluster. These clusters can be used to manipulate light on the nano scale.^[8]

Theory

The quasistatic equations that describe the scattering and absorbance cross-sections for very small spherical nanoparticles are:

${{\sigma }_{\rm {scatt}}}={\frac {8\pi }{3}}{{k}^{4}}{{R}^{6}}{{\left|{\frac {{{\varepsilon }_{\rm {particle}}}-{{\varepsilon }_{\rm {medium}}}}{{{\varepsilon }_{\rm {particle}}}+2{{\varepsilon }_{\rm {medium}}}}}\right|}^{2}}$

${{\sigma }_{\rm {abs}}}=4\pi k{{R}^{3}}\operatorname {Im} \left|{\frac {{{\varepsilon }_{\rm {particle}}}-{{\varepsilon }_{\rm {medium}}}}{{{\varepsilon }_{\rm {particle}}}+2{{\varepsilon }_{\rm {medium}}}}}\right|$

where $k$ is the wavenumber of the electric field, $R$ is the radius of the particle, ${{\varepsilon }_{\rm {medium}}}$ is the relative permittivity of the dielectric medium and ${{\varepsilon }_{\rm {particle}}}$ is the relative permittivity of the nanoparticle defined by

${{\varepsilon }_{\rm {particle}}}=1-{\frac {\omega _{\rm {p}}^{2}}{{{\omega }^{2}}+\mathrm {i} {\omega }{\gamma }}}$

also known as the Drude Model for free electrons where ${{\omega }_{\rm {p}}}$ is the plasma frequency, ${\gamma }$ is the relaxation frequency of the charge carries, and $\omega$ is the frequency of the electromagnetic radiation. This equation is the result of solving the differential equation for a harmonic oscillator with a driving force proportional to the electric field that the particle is subjected to. For a more thorough derivation, see surface plasmon.

It logically follows that the resonance conditions for these equations is reached when the denominator is around zero such that

${{\varepsilon }_{\rm {particle}}}+2{{\varepsilon }_{\rm {medium}}}\approx 0$

When this condition is fulfilled the cross-sections are at their maximum.

These cross-sections are for single, spherical particles. The equations change when particles are non-spherical, or are coupled to 1 or more other nanoparticles, such as when their geometry changes. This principle is important for several applications.

Rigorous electrodynamic analysis of plasma oscillations in a spherical metal nanoparticle of a finite size was performed in.^[9]

Applications

Plasmonic solar cells

Due to their ability to scatter light back into the photovoltaic structure and low absorption, plasmonic nanoparticles are under investigation as a method for increasing solar cell efficiency.^[10]^[5] Forcing more light to be absorbed by the dielectric increases efficiency.^[11]

Plasmons can be excited by optical radiation and induce an electric current from hot electrons in materials fabricated from gold particles and light-sensitive molecules of porphin, of precise sizes and specific patterns. The wavelength to which the plasmon responds is a function of the size and spacing of the particles. The material is fabricated using ferroelectric nanolithography. Compared to conventional photoexcitation, the material produced three to 10 times the current.^[12]^[13]

Spectroscopy

In the past 5 years plasmonic nanoparticles have been explored as a method for high resolution spectroscopy. One group utilized 40 nm gold nanoparticles that had been functionalized such that they would bind specifically to epidermal growth factor receptors to determine the density of those receptors on a cell. This technique relies on the fact that the effective geometry of the particles change when they appear within one particle diameter (40 nm) of each other. Within that range, quantitative information on the EGFR density in the cell membrane can be retrieved based on the shift in resonant frequency of the plasmonic particles.^[14]

Cancer treatment

Plasmonic nanoparticles have demonstrated a wide potential for the establishment of innovative cancer treatments.^[15] Despite that, there are still not plasmonic nanomaterials employed in the clinical practice, because the associated metal persistence.^[15] Preliminary research indicates that some nanomaterials, among which gold nanorods ^[16] and ultrasmall-in-nano architectures,^[17] can convert IR laser light into localized heat, also in combination with other established cancer treatments.^[18]

Related Research Articles

In electromagnetism, a dielectric is an electrical insulator that can be polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor, because they have no loosely bound, or free, electrons that may drift through the material, but instead they shift, only slightly, from their average equilibrium positions, causing dielectric polarisation. Because of dielectric polarisation, positive charges are displaced in the direction of the field and negative charges shift in the direction opposite to the field. This creates an internal electric field that reduces the overall field within the dielectric itself. If a dielectric is composed of weakly bonded molecules, those molecules not only become polarised, but also reorient so that their symmetry axes align to the field.

<span class="mw-page-title-main">Permittivity</span> Measure of the electric polarizability of a dielectric material

In electromagnetism, the absolute permittivity, often simply called permittivity and denoted by the Greek letter $ε$ (epsilon), is a measure of the electric polarizability of a dielectric material. A material with high permittivity polarizes more in response to an applied electric field than a material with low permittivity, thereby storing more energy in the material. In electrostatics, the permittivity plays an important role in determining the capacitance of a capacitor.

<span class="mw-page-title-main">Plasmon</span> Quasiparticle of charge oscillations in condensed matter

In physics, a plasmon is a quantum of plasma oscillation. Just as light consists of photons, the plasma oscillation consists of plasmons. The plasmon can be considered as a quasiparticle since it arises from the quantization of plasma oscillations, just like phonons are quantizations of mechanical vibrations. Thus, plasmons are collective oscillations of the free electron gas density. For example, at optical frequencies, plasmons can couple with a photon to create another quasiparticle called a plasmon polariton.

The Drude model of electrical conduction was proposed in 1900 by Paul Drude to explain the transport properties of electrons in materials. Basically, Ohm's law was well established and stated that the current J and voltage V driving the current are related to the resistance R of the material. The inverse of the resistance is known as the conductance. When we consider a metal of unit length and unit cross sectional area, the conductance is known as the conductivity, which is the inverse of resistivity. The Drude model attempts to explain the resistivity of a conductor in terms of the scattering of electrons by the relatively immobile ions in the metal that act like obstructions to the flow of electrons.

<span class="mw-page-title-main">Colloidal gold</span> Suspension of gold nanoparticles in a liquid

Colloidal gold is a sol or colloidal suspension of nanoparticles of gold in a fluid, usually water. The colloid is coloured usually either wine red or blue-purple . Due to their optical, electronic, and molecular-recognition properties, gold nanoparticles are the subject of substantial research, with many potential or promised applications in a wide variety of areas, including electron microscopy, electronics, nanotechnology, materials science, and biomedicine.

Plasma oscillations, also known as Langmuir waves, are rapid oscillations of the electron density in conducting media such as plasmas or metals in the ultraviolet region. The oscillations can be described as an instability in the dielectric function of a free electron gas. The frequency depends only weakly on the wavelength of the oscillation. The quasiparticle resulting from the quantization of these oscillations is the plasmon.

In plasmas and electrolytes, the Debye length, is a measure of a charge carrier's net electrostatic effect in a solution and how far its electrostatic effect persists. With each Debye length the charges are increasingly electrically screened and the electric potential decreases in magnitude by 1/e. A Debye sphere is a volume whose radius is the Debye length. Debye length is an important parameter in plasma physics, electrolytes, and colloids. The corresponding Debye screening wave vector $for particles of density, charge at a temperature is given by in Gaussian units. Expressions in MKS units will be given below. The analogous quantities at very low temperatures are known as the Thomas-Fermi length and the Thomas-Fermi wave vector. They are of interest in describing the behaviour of electrons in metals at room temperature.$

Dielectrophoresis (DEP) is a phenomenon in which a force is exerted on a dielectric particle when it is subjected to a non-uniform electric field. This force does not require the particle to be charged. All particles exhibit dielectrophoretic activity in the presence of electric fields. However, the strength of the force depends strongly on the medium and particles' electrical properties, on the particles' shape and size, as well as on the frequency of the electric field. Consequently, fields of a particular frequency can manipulate particles with great selectivity. This has allowed, for example, the separation of cells or the orientation and manipulation of nanoparticles and nanowires. Furthermore, a study of the change in DEP force as a function of frequency can allow the electrical properties of the particle to be elucidated.

Surface plasmon resonance (SPR) is a phenomenon that occurs where electrons in a thin metal sheet become excited by light that is directed to the sheet with a particular angle of incidence, and then travel parallel to the sheet. Assuming a constant light source wavelength and that the metal sheet is thin, the angle of incidence that triggers SPR is related to the refractive index of the material and even a small change in the refractive index will cause SPR to not be observed. This makes SPR a possible technique for detecting particular substances (analytes) and SPR biosensors have been developed to detect various important biomarkers.

<span class="mw-page-title-main">Surface-enhanced Raman spectroscopy</span> Spectroscopic technique

Surface-enhanced Raman spectroscopy or surface-enhanced Raman scattering (SERS) is a surface-sensitive technique that enhances Raman scattering by molecules adsorbed on rough metal surfaces or by nanostructures such as plasmonic-magnetic silica nanotubes. The enhancement factor can be as much as 10¹⁰ to 10¹¹, which means the technique may detect single molecules.

In materials science, effective medium approximations (EMA) or effective medium theory (EMT) pertain to analytical or theoretical modeling that describes the macroscopic properties of composite materials. EMAs or EMTs are developed from averaging the multiple values of the constituents that directly make up the composite material. At the constituent level, the values of the materials vary and are inhomogeneous. Precise calculation of the many constituent values is nearly impossible. However, theories have been developed that can produce acceptable approximations which in turn describe useful parameters including the effective permittivity and permeability of the materials as a whole. In this sense, effective medium approximations are descriptions of a medium based on the properties and the relative fractions of its components and are derived from calculations, and effective medium theory. There are two widely used formulae.

Photothermal therapy (PTT) refers to efforts to use electromagnetic radiation for the treatment of various medical conditions, including cancer. This approach is an extension of photodynamic therapy, in which a photosensitizer is excited with specific band light. This activation brings the sensitizer to an excited state where it then releases vibrational energy (heat), which is what kills the targeted cells.

Surface plasmons (SPs) are coherent delocalized electron oscillations that exist at the interface between any two materials where the real part of the dielectric function changes sign across the interface. SPs have lower energy than bulk plasmons which quantise the longitudinal electron oscillations about positive ion cores within the bulk of an electron gas.

A plasmonic-enhanced solar cell, commonly referred to simply as plasmonic solar cell, is a type of solar cell that converts light into electricity with the assistance of plasmons, but where the photovoltaic effect occurs in another material.

<span class="mw-page-title-main">Surface plasmon polariton</span> Electromagnetic waves that travel along an interface

Surface plasmon polaritons (SPPs) are electromagnetic waves that travel along a metal–dielectric or metal–air interface, practically in the infrared or visible-frequency. The term "surface plasmon polariton" explains that the wave involves both charge motion in the metal and electromagnetic waves in the air or dielectric ("polariton").

A plasmonic metamaterial is a metamaterial that uses surface plasmons to achieve optical properties not seen in nature. Plasmons are produced from the interaction of light with metal-dielectric materials. Under specific conditions, the incident light couples with the surface plasmons to create self-sustaining, propagating electromagnetic waves known as surface plasmon polaritons (SPPs). Once launched, the SPPs ripple along the metal-dielectric interface. Compared with the incident light, the SPPs can be much shorter in wavelength.

A localized surface plasmon (LSP) is the result of the confinement of a surface plasmon in a nanoparticle of size comparable to or smaller than the wavelength of light used to excite the plasmon. When a small spherical metallic nanoparticle is irradiated by light, the oscillating electric field causes the conduction electrons to oscillate coherently. When the electron cloud is displaced relative to its original position, a restoring force arises from Coulombic attraction between electrons and nuclei. This force causes the electron cloud to oscillate. The oscillation frequency is determined by the density of electrons, the effective electron mass, and the size and shape of the charge distribution. The LSP has two important effects: electric fields near the particle's surface are greatly enhanced and the particle's optical absorption has a maximum at the plasmon resonant frequency. Surface plasmon resonance can also be tuned based on the shape of the nanoparticle. The plasmon frequency can be related to the metal dielectric constant. The enhancement falls off quickly with distance from the surface and, for noble metal nanoparticles, the resonance occurs at visible wavelengths. Localized surface plasmon resonance creates brilliant colors in metal colloidal solutions.

Plasmonics or nanoplasmonics refers to the generation, detection, and manipulation of signals at optical frequencies along metal-dielectric interfaces in the nanometer scale. Inspired by photonics, plasmonics follows the trend of miniaturizing optical devices, and finds applications in sensing, microscopy, optical communications, and bio-photonics.

Spoof surface plasmons, also known as spoof surface plasmon polaritons and designer surface plasmons, are surface electromagnetic waves in microwave and terahertz regimes that propagate along planar interfaces with sign-changing permittivities. Spoof surface plasmons are a type of surface plasmon polariton, which ordinarily propagate along metal and dielectric interfaces in infrared and visible frequencies. Since surface plasmon polaritons cannot exist naturally in microwave and terahertz frequencies due to dispersion properties of metals, spoof surface plasmons necessitate the use of artificially-engineered metamaterials.

A nanoparticle interfacial layer is a well structured layer of typically organic molecules around a nanoparticle. These molecules are known as stabilizers, capping and surface ligands or passivating agents. The interfacial layer has a significant effect on the properties of the nanoparticle and is therefore often considered as an integral part of a nanoparticle. The interfacial layer has an typical thickness between 0.1 and 4 nm, which is dependent on the type of the molecules the layer is made of. The organic molecules that make up the interfacial layer are often amphiphilic molecules, meaning that they have a polar head group combined with a non-polar tail.

References

↑ Guay, Jean-Michel; Lesina, Antonino Calà; Côté, Guillaume; Charron, Martin; et al. (2017). "Laser-induced plasmonic colours on metals". Nature Communications . 8: 16095. arXiv: 1609.02874 . Bibcode:2017NatCo...816095G. doi: 10.1038/ncomms16095 . PMC 5520110 . PMID 28719576.
↑ Eustis, Susie; El-Sayed, Mostafa A. (2006). "Why gold nanoparticles are more precious than pretty gold: Noble metal surface plasmon resonance and its enhancement of the radiative and nonradiative properties of nanocrystals of different shapes". Chemical Society Reviews. 35 (3): 209–217. doi:10.1039/b514191e. PMID 16505915.
↑ Chen, Tianhong; Pourmand, Mahshid; Feizpour, Amin; Cushman, Bradford; Reinhard, Björn M. (3 July 2013). "Tailoring Plasmon Coupling in Self-Assembled One-Dimensional Au Nanoparticle Chains through Simultaneous Control of Size and Gap Separation". The Journal of Physical Chemistry Letters. 4 (13): 2147–2152. doi:10.1021/jz401066g. PMC 3766581 . PMID 24027605.
↑ Zeng, Shuwen; Yu, Xia; Law, Wing-Cheung; Zhang, Yating; Hu, Rui; Dinh, Xuan-Quyen; Ho, Ho-Pui; Yong, Ken-Tye (January 2013). "Size dependence of Au NP-enhanced surface plasmon resonance based on differential phase measurement". Sensors and Actuators B: Chemical. 176: 1128–1133. doi:10.1016/j.snb.2012.09.073.
1 2 Yu, Peng; Yao, Yisen; Wu, Jiang; Niu, Xiaobin; Rogach, Andrey L.; Wang, Zhiming (9 August 2017). "Effects of Plasmonic Metal Core -Dielectric Shell Nanoparticles on the Broadband Light Absorption Enhancement in Thin Film Solar Cells". Scientific Reports. 7 (1): 7696. Bibcode:2017NatSR...7.7696Y. doi:10.1038/s41598-017-08077-9. PMC 5550503 . PMID 28794487.
↑ Wu, Jiang; Yu, Peng; Susha, Andrei S.; Sablon, Kimberly A.; Chen, Haiyuan; Zhou, Zhihua; Li, Handong; Ji, Haining; Niu, Xiaobin; Govorov, Alexander O.; Rogach, Andrey L.; Wang, Zhiming M. (April 2015). "Broadband efficiency enhancement in quantum dot solar cells coupled with multispiked plasmonic nanostars". Nano Energy. 13: 827–835. doi:10.1016/j.nanoen.2015.02.012. S2CID 98282021.
↑ Hurtado-Aviles, E.A.; Torres, J.A.; Trejo-Valdez, M.; Urriolagoitia-Sosa, G.; Villalpando, I.; Torres-Torres, C. (28 October 2017). "Acousto-Plasmonic Sensing Assisted by Nonlinear Optical Interactions in Bimetallic Au-Pt Nanoparticles". Micromachines. 8 (11): 321. doi: 10.3390/mi8110321 . PMC 6189711 . PMID 30400510.
↑ Chuntonov, Lev; Haran, Gilad (8 June 2011). "Trimeric Plasmonic Molecules: The Role of Symmetry". Nano Letters. 11 (6): 2440–2445. Bibcode:2011NanoL..11.2440C. doi:10.1021/nl2008532. PMID 21553898.
↑ Belyaev, B.A.; Tyurnev, V.V. (August 2016). "Resonances of electromagnetic oscillations in a spherical metal nanoparticle". Microwave and Optical Technology Letters. 58 (8): 1883–1886. doi:10.1002/mop.29930.
↑ Yue, Zengji; Cai, Boyuan; Wang, Lan; Wang, Xiaolin; Gu, Min (4 March 2016). "Intrinsically core-shell plasmonic dielectric nanostructures with ultrahigh refractive index". Science Advances. 2 (3): e1501536. Bibcode:2016SciA....2E1536Y. doi:10.1126/sciadv.1501536. PMC 4820380 . PMID 27051869.
↑ Ferry, Vivian E.; Munday, Jeremy N.; Atwater, Harry A. (16 November 2010). "Design Considerations for Plasmonic Photovoltaics". Advanced Materials. 22 (43): 4794–4808. Bibcode:2010AdM....22.4794F. doi:10.1002/adma.201000488. PMID 20814916.
↑ "A new method for harvesting energy from light". Kurzweil Accelerating Intelligence. Kurzweil Library. September 12, 2013. Retrieved 9 Feb 2020.
↑ Conklin, David; Nanayakkara, Sanjini; Park, Tae-Hong; Lagadec, Marie F.; Stecher, Joshua T.; Chen, Xi; Therien, Michael J.; Bonnell, Dawn A. (28 May 2013). "Exploiting Plasmon-Induced Hot Electrons in Molecular Electronic Devices". ACS Nano. 7 (5): 4479–4486. doi:10.1021/nn401071d. PMID 23550717.
↑ Wang, Jing; Boriskina, Svetlana V.; Wang, Hongyun; Reinhard, Björn M. (23 August 2011). "Illuminating Epidermal Growth Factor Receptor Densities on Filopodia through Plasmon Coupling". ACS Nano. 5 (8): 6619–6628. doi:10.1021/nn202055b. PMC 3204364 . PMID 21761914.
1 2 Cassano, Domenico; Pocoví-Martínez, Salvador; Voliani, Valerio (17 January 2018). "Ultrasmall-in-Nano Approach: Enabling the Translation of Metal Nanomaterials to Clinics". Bioconjugate Chemistry. 29 (1): 4–16. doi: 10.1021/acs.bioconjchem.7b00664 . PMID 29186662.
↑ C.S., Rejiya; Kumar, Jatish; V., Raji; M., Vibin; Abraham, Annie (February 2012). "Laser immunotherapy with gold nanorods causes selective killing of tumour cells". Pharmacological Research. 65 (2): 261–269. doi:10.1016/j.phrs.2011.10.005. PMID 22115972.
↑ Cassano, Domenico; Santi, Melissa; D’Autilia, Francesca; Mapanao, Ana Katrina; Luin, Stefano; Voliani, Valerio (2019). "Photothermal effect by NIR-responsive excretable ultrasmall-in-nano architectures". Materials Horizons. 6 (3): 531–537. doi: 10.1039/C9MH00096H . hdl: 11384/77439 .
↑ Mapanao, Ana Katrina; Santi, Melissa; Voliani, Valerio (January 2021). "Combined chemo-photothermal treatment of three-dimensional head and neck squamous cell carcinomas by gold nano-architectures". Journal of Colloid and Interface Science. 582 (Pt B): 1003–1011. Bibcode:2021JCIS..582.1003M. doi:10.1016/j.jcis.2020.08.059. PMID 32927167. S2CID 221723222.

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[1] Guay, Jean-Michel; Lesina, Antonino Calà; Côté, Guillaume; Charron, Martin; et al. (2017). "Laser-induced plasmonic colours on metals". Nature Communications . 8: 16095. arXiv: 1609.02874 . Bibcode:2017NatCo...816095G. doi: 10.1038/ncomms16095 . PMC 5520110 . PMID 28719576.

[2] Eustis, Susie; El-Sayed, Mostafa A. (2006). "Why gold nanoparticles are more precious than pretty gold: Noble metal surface plasmon resonance and its enhancement of the radiative and nonradiative properties of nanocrystals of different shapes". Chemical Society Reviews. 35 (3): 209–217. doi:10.1039/b514191e. PMID 16505915.

[3] Chen, Tianhong; Pourmand, Mahshid; Feizpour, Amin; Cushman, Bradford; Reinhard, Björn M. (3 July 2013). "Tailoring Plasmon Coupling in Self-Assembled One-Dimensional Au Nanoparticle Chains through Simultaneous Control of Size and Gap Separation". The Journal of Physical Chemistry Letters. 4 (13): 2147–2152. doi:10.1021/jz401066g. PMC 3766581 . PMID 24027605.

[4] Zeng, Shuwen; Yu, Xia; Law, Wing-Cheung; Zhang, Yating; Hu, Rui; Dinh, Xuan-Quyen; Ho, Ho-Pui; Yong, Ken-Tye (January 2013). "Size dependence of Au NP-enhanced surface plasmon resonance based on differential phase measurement". Sensors and Actuators B: Chemical. 176: 1128–1133. doi:10.1016/j.snb.2012.09.073.

[:0-5] 1 2 Yu, Peng; Yao, Yisen; Wu, Jiang; Niu, Xiaobin; Rogach, Andrey L.; Wang, Zhiming (9 August 2017). "Effects of Plasmonic Metal Core -Dielectric Shell Nanoparticles on the Broadband Light Absorption Enhancement in Thin Film Solar Cells". Scientific Reports. 7 (1): 7696. Bibcode:2017NatSR...7.7696Y. doi:10.1038/s41598-017-08077-9. PMC 5550503 . PMID 28794487.

[6] Wu, Jiang; Yu, Peng; Susha, Andrei S.; Sablon, Kimberly A.; Chen, Haiyuan; Zhou, Zhihua; Li, Handong; Ji, Haining; Niu, Xiaobin; Govorov, Alexander O.; Rogach, Andrey L.; Wang, Zhiming M. (April 2015). "Broadband efficiency enhancement in quantum dot solar cells coupled with multispiked plasmonic nanostars". Nano Energy. 13: 827–835. doi:10.1016/j.nanoen.2015.02.012. S2CID 98282021.

[7] Hurtado-Aviles, E.A.; Torres, J.A.; Trejo-Valdez, M.; Urriolagoitia-Sosa, G.; Villalpando, I.; Torres-Torres, C. (28 October 2017). "Acousto-Plasmonic Sensing Assisted by Nonlinear Optical Interactions in Bimetallic Au-Pt Nanoparticles". Micromachines. 8 (11): 321. doi: 10.3390/mi8110321 . PMC 6189711 . PMID 30400510.

[8] Chuntonov, Lev; Haran, Gilad (8 June 2011). "Trimeric Plasmonic Molecules: The Role of Symmetry". Nano Letters. 11 (6): 2440–2445. Bibcode:2011NanoL..11.2440C. doi:10.1021/nl2008532. PMID 21553898.

[9] Belyaev, B.A.; Tyurnev, V.V. (August 2016). "Resonances of electromagnetic oscillations in a spherical metal nanoparticle". Microwave and Optical Technology Letters. 58 (8): 1883–1886. doi:10.1002/mop.29930.

[10] Yue, Zengji; Cai, Boyuan; Wang, Lan; Wang, Xiaolin; Gu, Min (4 March 2016). "Intrinsically core-shell plasmonic dielectric nanostructures with ultrahigh refractive index". Science Advances. 2 (3): e1501536. Bibcode:2016SciA....2E1536Y. doi:10.1126/sciadv.1501536. PMC 4820380 . PMID 27051869.

[11] Ferry, Vivian E.; Munday, Jeremy N.; Atwater, Harry A. (16 November 2010). "Design Considerations for Plasmonic Photovoltaics". Advanced Materials. 22 (43): 4794–4808. Bibcode:2010AdM....22.4794F. doi:10.1002/adma.201000488. PMID 20814916.

[12] "A new method for harvesting energy from light". Kurzweil Accelerating Intelligence. Kurzweil Library. September 12, 2013. Retrieved 9 Feb 2020.

[13] Conklin, David; Nanayakkara, Sanjini; Park, Tae-Hong; Lagadec, Marie F.; Stecher, Joshua T.; Chen, Xi; Therien, Michael J.; Bonnell, Dawn A. (28 May 2013). "Exploiting Plasmon-Induced Hot Electrons in Molecular Electronic Devices". ACS Nano. 7 (5): 4479–4486. doi:10.1021/nn401071d. PMID 23550717.

[14] Wang, Jing; Boriskina, Svetlana V.; Wang, Hongyun; Reinhard, Björn M. (23 August 2011). "Illuminating Epidermal Growth Factor Receptor Densities on Filopodia through Plasmon Coupling". ACS Nano. 5 (8): 6619–6628. doi:10.1021/nn202055b. PMC 3204364 . PMID 21761914.

[Cassano_4–16-15] 1 2 Cassano, Domenico; Pocoví-Martínez, Salvador; Voliani, Valerio (17 January 2018). "Ultrasmall-in-Nano Approach: Enabling the Translation of Metal Nanomaterials to Clinics". Bioconjugate Chemistry. 29 (1): 4–16. doi: 10.1021/acs.bioconjchem.7b00664 . PMID 29186662.

[16] C.S., Rejiya; Kumar, Jatish; V., Raji; M., Vibin; Abraham, Annie (February 2012). "Laser immunotherapy with gold nanorods causes selective killing of tumour cells". Pharmacological Research. 65 (2): 261–269. doi:10.1016/j.phrs.2011.10.005. PMID 22115972.

[17] Cassano, Domenico; Santi, Melissa; D’Autilia, Francesca; Mapanao, Ana Katrina; Luin, Stefano; Voliani, Valerio (2019). "Photothermal effect by NIR-responsive excretable ultrasmall-in-nano architectures". Materials Horizons. 6 (3): 531–537. doi: 10.1039/C9MH00096H . hdl: 11384/77439 .

[18] Mapanao, Ana Katrina; Santi, Melissa; Voliani, Valerio (January 2021). "Combined chemo-photothermal treatment of three-dimensional head and neck squamous cell carcinomas by gold nano-architectures". Journal of Colloid and Interface Science. 582 (Pt B): 1003–1011. Bibcode:2021JCIS..582.1003M. doi:10.1016/j.jcis.2020.08.059. PMID 32927167. S2CID 221723222.

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