The overall aim of the International Nano Letters is to bring science and applications together on nanoscale and nanostructured materials with emphasis on synthesis, processing, characterization, and applications of materials. Currently a popular area in nanomedicine is the implementation of plasmonic gold nanoparticles for cancer diagnosis and photothermal therapy, attributed to the.
Optical properties and implementations in cancer diagnosis and photothermal therapy. Abstract. Currently a popular area in nanomedicine is the implementation of plasmonic gold nanoparticles for cancer diagnosis and photothermal therapy, attributed to the intriguing optical properties of the nanoparticles. The surface plasmon resonance, a unique phenomenon to plasmonic (noble metal) nanoparticles leads to strong electromagnetic fields on the particle surface and consequently enhances all the radiative properties such as absorption and scattering. Additionally, the strongly absorbed light is converted to heat quickly via a series of nonradiative processes.
- Abstract. Amyloid fibril-based ultralow-density aerogels are designed by functionalization with gold nanoparticles and microcrystals, leading to hybrids of unprecedented lightness and functionality. By changing the colloidal.
- Antimicrobial NPs. Antibacterial activity is related to compounds that locally kill bacteria or slow down their growth, without being in general toxic to surrounding tissue. Most current antibacterial agents are chemically.
Generally, gold nanoparticles are produced in a liquid ('liquid chemical methods') by reduction of chloroauric acid (H[AuCl 4]). After dissolving H[AuCl 4], the solution is rapidly stirred while a reducing agent is added. This.
In this review, we discuss these important optical and photothermal properties of gold nanoparticles in different shapes and structures and address their recent applications for cancer imaging, spectroscopic detection and photothermal therapy. Keywords. Gold nanoparticles; Cancer; Imaging; Photothermal therapy. Introduction. Nanomedicine is currently an active field. This is because new properties emerge when the size of a matter is reduced from bulk to the nanometer scale [1] and [2]. These new properties, including optical, magnetic, electronic, and structural properties, make nano- sized particles (generally 1–1. Plasmonic (noble metal) nanoparticles distinguish themselves from other nanoplatforms such as semiconductor quantum dots, magnetic and polymeric nanoparticle by their unique surface plasmon resonance (SPR). This SPR, resulting from photon confinement to a small particle size, enhances all the radiative and nonradiative properties of the nanoparticles [4], [5] and [6] and thus offering multiple modalities for biological and medical applicaitons [7], [8], [9], [1.
Gold nanoparticles (Au NPs) have been brought to the forefront of cancer research in recent years because of their facile synthesis and surface modification, strongly enhanced and tunable optical properties as well as excellent biocompatibility feasible for clinic settings. High quality, high yield and size controllable colloidal gold can be quickly prepared by the well- known citrate reduction method [1. Synthetic advancement in the last decade engenders Au NPs of different shapes and structure [1. Au NPs [2. 1], which all show largely red- shifted properties boosting their values in photothermal cancer therapy [2.
The strongly enhanced radiative properties such as absorption, scattering and plasmonic field for surface enhanced Raman of adjacent molecules make them extremely useful for molecular cancer imaging [2. In this review, we will introduce the optical and photothermal properties of Au NPs in different shapes and structures starting with the elucidation of surface plasmon resonance. Their biomedical applications in cancer imaging using light scattering properties, spectroscopic cancer detection using surface enhanced Raman and photothermal therapy using nonradiative properties will be summarized and discussed. Surface plasmon resonance. The enchantment of Au NPs since ancient times, as reflected in their intense color, originates from the basic photophysical response that does not exist to nonmetallic particles. When a metal particle is exposed to light, the oscillating electromagnetic field of the light induces a collective coherent oscillation of the free electrons (conduction band electrons) of the metal. This electron oscillation around the particle surface causes a charge separation with respect to the ionic lattice, forming a dipole oscillation along the direction of the electric field of the light (Fig.
A). The amplitude of the oscillation reaches maximum at a specific frequency, called surface plasmon resonance (SPR) [2. The SPR induces a strong absorption of the incident light and thus can be measured using a UV–Vis absorption spectrometer. The SPR band is much stronger for plasmonc nanoparticles (noble metal, especially Au and Ag) than other metals. The SPR band intensity and wavelength depends on the factors affecting the electron charge density on the particle surface such as the metal type, particle size, shape, structure, composition and the dielectric constant of the surrounding medium, as theoretically described by Mie theory [2.
For particles smaller than 2. SPR can be quantitatively explained according to the following simple equation [4], [5], [6], [8], [2. Cext is the extinction cross- section which is related to extinction coefficient by Оµ (M−1 cm−1) = 1. N0. Cext(cm. 2)/2.
О» is the wavelength of the incident light, Оµ is the complex dielectric constant of the metal given by Оµ = Оµr(П‰) + i. Оµi(П‰), Оµr(П‰) is the real part and Оµi(П‰) is the imagery part of the dielectric function of the metal, Оµm is the dielectric constant of the surrounding medium which is related to the refractive index of the medium by Оµm=nm.
The real part of the dielectric constant of the metal determines the SPR position and the imagery part determines the bandwidth. The SPR resonance occurs when Оµr(П‰) = −2. Оµm. Gold, silver and copper nanoparticles show strong SPR bands in the visible region while other metals show broad and weak band in the UV region [3.