|
Photothermal Therapy
Photothermal therapy (PTT) refers to efforts to use electromagnetic radiation (most often in infrared wavelengths) for the treatment of various medical conditions, including cancer. This neurotherapy 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. Unlike photodynamic therapy, photothermal therapy does not require oxygen to interact with the target cells or tissues. Current studies also show that photothermal therapy is able to use longer wavelength light, which is less energetic and therefore less harmful to other cells and tissues. Nanoscale materials Most materials of interest currently being investigated for photothermal therapy are on the nanoscale. One of the key reasons behind this is the enhanced permeability and retention effect observed with particles in a certain size ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnetic Radiation
In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength, ranging from radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. All forms of EMR travel at the speed of light in a vacuum and exhibit wave–particle duality, behaving both as waves and as discrete particles called photons. Electromagnetic radiation is produced by accelerating charged particles such as from the Sun and other celestial bodies or artificially generated for various applications. Its interaction with matter depends on wavelength, influencing its uses in communication, medicine, industry, and scientific research. Radio waves enable broadcasting and wireless communication, infrared is used in thermal imaging, visible light is essential for vision, and higher-energy radiation, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Near-infrared Window In Biological Tissue
The near-infrared (NIR) window (also known as optical window or therapeutic window) defines the range of wavelengths from 650 to 1350 nanometre (nm) where light has its maximum depth of penetration in tissue. Within the NIR window, scattering is the most dominant light-tissue interaction, and therefore the propagating light becomes diffused rapidly. Since scattering increases the distance travelled by photons within tissue, the probability of photon absorption also increases. Because scattering has weak dependence on wavelength, the NIR window is primarily limited by the light absorption of blood at short wavelengths and water at long wavelengths. The technique using this window is called NIRS. Medical imaging techniques such as fluorescence image-guided surgery often make use of the NIR window to detect deep structures. Absorption properties of tissue components The absorption coefficient (\mu_) is defined as the probability of photon absorption in tissue per unit path length. D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polydopamine
Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical of the catecholamine and phenethylamine families. It is an amine synthesized by removing a carboxyl group from a molecule of its precursor chemical, L-DOPA, which is synthesized in the brain and kidneys. Dopamine is also synthesized in plants and most animals. In the brain, dopamine functions as a neurotransmitter—a chemical released by neurons (nerve cells) to send signals to other nerve cells. The brain includes several distinct dopamine pathways, one of which plays a major role in the motivational component of reward-motivated behavior. The anticipation of most types of rewards increases the level of dopamine in the brain, and many addictive drugs increase dopamine release or block its reuptake into neurons following release. Other brain dopamine pathways are involved in motor control and in controlling the relea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polythiophene
Polythiophenes (PTs) are polymerized thiophenes, a sulfur heterocyclic compound, heterocycle. The parent PT is an insoluble colored solid with the formula (C4H2S)n.Strictly speaking, "polythiophene" is a misnomer, since the polymer consists of thienylene (2,5-C4H2S) repeat units. Similarly, thiophene is not a monomer as such. The rings are linked through the 2- and 5-positions. Poly(alkylthiophene)s have alkyl substituents at the 3- or 4-position(s). They are also colored solids, but tend to be soluble in organic solvents. PTs become Conductive polymer, conductive when oxidized. The electrical resistivity and conductivity, electrical conductivity results from the Delocalized electron, delocalization of electrons along the polymer backbone. Conductivity however is not the only interesting property resulting from electron delocalization. The optical properties of these materials respond to environmental stimuli, with dramatic color shifts in response to changes in solvent, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polypyrrole
Polypyrrole (PPy) is an organic polymer obtained by oxidative polymerization of pyrrole. It is a solid with the formula H(C4H2NH)nH. It is an intrinsically conducting polymer, used in electronics, optical, biological and medical fields. History Some of the first examples of PPy were reported in 1919 by Angeli and Pieroni, who reported the formation of pyrrole blacks from pyrrole magnesium bromide. Since then pyrrole oxidation reaction has been studied and reported in scientific literature. Work on conductive polymers including polypyrrole, polythiophene, polyaniline, and polyacetylene was awarded the Nobel Prize in Chemistry in 2000 to Alan J. Heeger, Alan G. MacDiarmid and Hideki Shirakawa . Synthesis Different methods can be used to synthesize PPy, but the most common are electrochemical synthesis and chemical oxidation. Chemical oxidation of pyrrole: :n C4H4NH + 2n FeCl3 → (C4H2NH)n + 2n FeCl2 + 2n HCl The process is thought to occur via the formation of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyaniline
Polyaniline (PANI) is a conducting polymer and organic semiconductor of the semi-flexible rod polymer family. The compound has been of interest since the 1980s because of its electrical conductivity and mechanical properties. Polyaniline is one of the most studied conducting polymers. Historical development Polyaniline was discovered in the 19th century by F. Ferdinand Runge (1794–1867), Carl Fritzsche (1808–1871), John Lightfoot (1831–1872), and Henry Letheby (1816–1876). Lightfoot studied the oxidation of aniline, which had been isolated only 20 years previously. He developed the first commercially successful route to the dye called Aniline black. The first definitive report of polyaniline did not occur until 1862, which included an electrochemical method for the determination of small quantities of aniline. From the early 20th century on, occasional reports about the structure of PANI were published. Polymerized from the inexpensive aniline, polyaniline can be fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytotoxicity
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are toxic metals, toxic chemicals, microbe neurotoxins, radiation particles and even specific neurotransmitters when the system is out of balance. Also some types of drugs, e.g alcohol, and some venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa'') are toxic to cells. Cell physiology Treating cells with the cytotoxic compound can result in a variety of prognoses. The cells may undergo necrosis, in which they lose membrane integrity and die rapidly as a result of cell lysis. The cells can stop actively growing and dividing (a decrease in cell viability), or the cells can activate a genetic program of controlled cell death (apoptosis). Cells undergoing necrosis typically exhibit rapid swelling, lose membrane integrity, shut down metabolism, and release their contents into the environment. Cells that undergo rapid necrosis in vitro do not have sufficient ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conjugated Polymers
In physical organic chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in a molecule, which in general lowers the overall energy of the molecule and increases stability. It is conventionally represented as having alternating single and multiple bonds. Lone pairs, radicals or carbenium ions may be part of the system, which may be cyclic, acyclic, linear or mixed. The term "conjugated" was coined in 1899 by the German chemist Johannes Thiele. Conjugation is the overlap of one p-orbital with another across an adjacent σ bond (in transition metals, d-orbitals can be involved). A conjugated system has a region of overlapping p-orbitals, bridging the interjacent locations that simple diagrams illustrate as not having a π bond. They allow a delocalization of π electrons across all the adjacent aligned p-orbitals. The π electrons do not belong to a single bond or atom, but rather to a group of atoms. Molecules containing conjugated sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phthalocyanine
Phthalocyanine () is a large, aromatic, macrocyclic, organic compound with the formula and is of theoretical or specialized interest in chemical dyes and photoelectricity. It is composed of four isoindole units linked by a ring of nitrogen atoms. = has a two-dimensional geometry and a ring system consisting of 18 π-electrons. The extensive delocalization of the π-electrons affords the molecule useful properties, lending itself to applications in dyes and pigments. Metal complexes derived from , the conjugate base of , are valuable in catalysis, organic solar cells, and photodynamic therapy. Properties Phthalocyanine and derived metal complexes (MPc) tend to aggregate and, thus, have low solubility in common solvents. Benzene at 40 °C dissolves less than a milligram of or CuPc per litre. and CuPc dissolve easily in sulfuric acid due to the protonation of the nitrogen atoms bridging the pyrrole rings. Many phthalocyanine compounds are, thermally, very s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porphyrin
Porphyrins ( ) are heterocyclic, macrocyclic, organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (). In vertebrates, an essential member of the porphyrin group is heme, which is a component of hemoproteins, whose functions include carrying oxygen in the bloodstream. In plants, an essential porphyrin derivative is chlorophyll, which is involved in light harvesting and electron transfer in photosynthesis. The parent of porphyrins is porphine, a rare chemical compound of exclusively theoretical interest. Substituted porphines are called porphyrins. With a total of 26 π-electrons the porphyrin ring structure is a coordinated aromatic system. One result of the large conjugated system is that porphyrins absorb strongly in the visible region of the electromagnetic spectrum, i.e. they are deeply colored. The name "porphyrin" derives . Structure Porphyrin complexes consist of a square planar MN4 core. The p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanine
Cyanines, also referred to as tetramethylindo(di)-carbocyanines are a synthetic dye family belonging to the polymethine group. Although the name derives etymologically from terms for shades of blue, the cyanine family covers the electromagnetic spectrum from infrared, near IR to ultraviolet, UV. Chemically, cyanines are a Conjugated system, conjugated system between two nitrogen atoms; in each resonance structure, exactly one nitrogen atom is oxidized to an iminium. Typically, they form part of a nitrogenous heterocycle, heterocyclic system. The main application for cyanine dyes is in Fluorescence microscopy, biological labeling. Nevertheless, there is a wide literature on both their synthesis and uses, and cyanines are common in some CD and DVD media. Structure Cyanines have been classified in many ways: * ''Streptocyanines'' or ''open chain cyanines'': : R2N+=CH[CH=CH]''n''-NR2 (I) * ''Hemicyanines'': : Aryl=N+=CH[CH=CH]''n''-NR2 (II) * ''Closed chain cyanines'': :Ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conjugated Polymers
In physical organic chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in a molecule, which in general lowers the overall energy of the molecule and increases stability. It is conventionally represented as having alternating single and multiple bonds. Lone pairs, radicals or carbenium ions may be part of the system, which may be cyclic, acyclic, linear or mixed. The term "conjugated" was coined in 1899 by the German chemist Johannes Thiele. Conjugation is the overlap of one p-orbital with another across an adjacent σ bond (in transition metals, d-orbitals can be involved). A conjugated system has a region of overlapping p-orbitals, bridging the interjacent locations that simple diagrams illustrate as not having a π bond. They allow a delocalization of π electrons across all the adjacent aligned p-orbitals. The π electrons do not belong to a single bond or atom, but rather to a group of atoms. Molecules containing conjugated sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
