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Photoluminescence is light emission from any form of matter after the absorption of photons. It is one of many forms of luminescence and is initiated by photoexcitation, hence the prefix photo-. Following excitation, various relaxation processes typically occur in which other photons are re-radiated. Time periods between absorption and emission may vary: ranging from short femtosecond-regime for emission involving free-carrier plasma in inorganic semiconductors up to milliseconds for phosphoresence processes in molecular systems; and under special circumstances delay of emission may even span to minutes or hours.
In organic chemistry, polyenes are poly-unsaturated, organic compounds that contain at least three alternating double and single carbon–carbon bonds. These carbon–carbon double bonds interact in a process known as conjugation, resulting in some unusual optical properties. Related to polyenes are dienes, where there are only two alternating double and single bonds.
Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluorescence, a phosphorescent material does not immediately reemit the radiation it absorbs. Instead, a phosphorescent material absorbs some of the radiation energy and reemits it for a much longer time after the radiation source is removed.
Amyloids are aggregates of proteins characterised by a fibrillar morphology of typically 7–13 nm in diameter, a β-sheet secondary structure and ability to be stained by particular dyes, such as Congo red. In the human body, amyloids have been linked to the development of various diseases. Pathogenic amyloids form when previously healthy proteins lose their normal structure and physiological functions (misfolding) and form fibrous deposits within and around cells. These protein misfolding and deposition processes disrupt the healthy function of tissues and organs.
Capillary electrophoresis (CE) is a family of electrokinetic separation methods performed in submillimeter diameter capillaries and in micro- and nanofluidic channels. Very often, CE refers to capillary zone electrophoresis (CZE), but other electrophoretic techniques including capillary gel electrophoresis (CGE), capillary isoelectric focusing (CIEF), capillary isotachophoresis and micellar electrokinetic chromatography (MEKC) belong also to this class of methods. In CE methods, analytes migrate through electrolyte solutions under the influence of an electric field. Analytes can be separated according to ionic mobility and/or partitioning into an alternate phase via non-covalent interactions. Additionally, analytes may be concentrated or "focused" by means of gradients in conductivity and pH.
Aptamers are oligomers of artificial ssDNA, RNA, XNA, or peptide that bind a specific target molecule, or family of target molecules. They exhibit a range of affinities, with variable levels of off-target binding and are sometimes classified as chemical antibodies. Aptamers and antibodies can be used in many of the same applications, but the nucleic acid-based structure of aptamers, which are mostly oligonucleotides, is very different from the amino acid-based structure of antibodies, which are proteins. This difference can make aptamers a better choice than antibodies for some purposes.
Molecular motors are natural (biological) or artificial molecular machines that are the essential agents of movement in living organisms. In general terms, a motor is a device that consumes energy in one form and converts it into motion or mechanical work; for example, many protein-based molecular motors harness the chemical free energy released by the hydrolysis of ATP in order to perform mechanical work. In terms of energetic efficiency, this type of motor can be superior to currently available man-made motors. One important difference between molecular motors and macroscopic motors is that molecular motors operate in the thermal bath, an environment in which the fluctuations due to thermal noise are significant.
Thioflavins are fluorescent dyes that are available as at least two compounds, namely Thioflavin T and Thioflavin S. Both are used for histology staining and biophysical studies of protein aggregation. In particular, these dyes have been used since 1989 to investigate amyloid formation. They are also used in biophysical studies of the electrophysiology of bacteria. Thioflavins are corrosive, irritant, and acutely toxic, causing serious eye damage. Thioflavin T has been used in research into Alzheimer's disease and other neurodegenerative diseases.
A molecular sensor or chemosensor is a molecular structure that is used for sensing of an analyte to produce a detectable change or a signal. The action of a chemosensor, relies on an interaction occurring at the molecular level, usually involves the continuous monitoring of the activity of a chemical species in a given matrix such as solution, air, blood, tissue, waste effluents, drinking water, etc. The application of chemosensors is referred to as chemosensing, which is a form of molecular recognition. All chemosensors are designed to contain a signalling moiety and a recognition moiety, that is connected either directly to each other or through a some kind of connector or a spacer. The signalling is often optically based electromagnetic radiation, giving rise to changes in either the ultraviolet and visible absorption or the emission properties of the sensors. Chemosensors may also be electrochemically based. Small molecule sensors are related to chemosensors. These are traditionally, however, considered as being structurally simple molecules and reflect the need to form chelating molecules for complexing ions in analytical chemistry. Chemosensors are synthetic analogues of biosensors, the difference being that biosensors incorporate biological receptors such as antibodies, aptamers or large biopolymers.
AIE may refer to:
The optical properties of carbon nanotubes are highly relevant for materials science. The way those materials interact with electromagnetic radiation is unique in many respects, as evidenced by their peculiar absorption, photoluminescence (fluorescence), and Raman spectra.
Crystallization of polymers is a process associated with partial alignment of their molecular chains. These chains fold together and form ordered regions called lamellae, which compose larger spheroidal structures named spherulites. Polymers can crystallize upon cooling from melting, mechanical stretching or solvent evaporation. Crystallization affects optical, mechanical, thermal and chemical properties of the polymer. The degree of crystallinity is estimated by different analytical methods and it typically ranges between 10 and 80%, with crystallized polymers often called "semi-crystalline". The properties of semi-crystalline polymers are determined not only by the degree of crystallinity, but also by the size and orientation of the molecular chains.
Polyfluorene is a polymer with formula (C13H8)n, consisting of fluorene units linked in a linear chain — specifically, at carbon atoms 2 and 7 in the standard fluorene numbering. It can also be described as a chain of benzene rings linked in para positions with an extra methylene bridge connecting every pair of rings.
A J-aggregate is a type of dye with an absorption band that shifts to a longer wavelength of increasing sharpness when it aggregates under the influence of a solvent or additive or concentration as a result of supramolecular self-organisation. The dye can be characterized further by a small Stokes shift with a narrow band. The J in J-aggregate refers to E.E. Jelley who discovered the phenomenon in 1936. The dye is also called a Scheibe aggregate after G. Scheibe who also independently published on this topic in 1937.
Nanoclusters are atomically precise, crystalline materials most often existing on the 0-2 nanometer scale. They are often considered kinetically stable intermediates that form during the synthesis of comparatively larger materials such as semiconductor and metallic nanocrystals. The majority of research conducted to study nanoclusters has focused on characterizing their crystal structures and understanding their role in the nucleation and growth mechanisms of larger materials.
Carbon quantum dots also commonly called carbon nano dots or simply carbon dots are carbon nanoparticles which are less than 10 nm in size and have some form of surface passivation.
Diketopyrrolopyrroles (DPPs) are organic dyes and pigments based on the heterocyclic dilactam 2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione, widely used in optoelectronics. DPPs were initially used as pigments in the painting industry due to their high resistance to photodegradation. More recently, DPP derivatives have been also investigated as promising fluorescent dyes for bioimaging applications, as well as components of materials for use in organic electronics.
Thermally activated delayed fluorescence (TADF) is a process through which surrounding thermal energy changes population of excited states of molecular compounds and thus, alters light emission. The TADF process usually involves an excited molecular species in a triplet state, which commonly has a forbidden transition to the singlet ground state, termed phosphorescence. By absorbing nearby thermal energy, the triplet state can undergo reverse intersystem crossing (RISC) converting the triplet state population to an excited singlet state, which then emits light to the singlet ground state in a delayed process termed delayed fluorescence. Accordingly, in many cases, the TADF molecules show two types of emission, a delayed fluorescence and a prompt fluorescence. This is found for specific organic molecules, but also for selected organo-transition metal compounds, such as Cu(I) complexes. Along with traditional fluorescent molecules and phosphorescent molecules, TADF compounds belong to the three main light-emitting material groups used in organic light-emitting diodes (OLEDs).
Bin Liu is a chemist who is Professor and Provost's Chair at the National University of Singapore. Her research considers polymer chemistry and organic functional materials. She was appointed Vice President of Research and Technology in 2019. She was awarded the 2021 Royal Society of Chemistry Centenary Prize.
References
- ↑ Hong, Yuning; Lam, Jacky W. Y.; Tang, Ben Zhong (2011). "Aggregation-induced emission". Chemical Society Reviews. 40 (11): 5361–88. doi:10.1039/c1cs15113d. PMID 21799992.
- ↑ Mei, Ju; Hong, Yuning; Lam, Jacky W. Y.; Qin, Anjun; Tang, Youhong; Tang, Ben Zhong (August 2014). "Aggregation-Induced Emission: The Whole Is More Brilliant than the Parts". Advanced Materials. 26 (31): 5429–5479. Bibcode:2014AdM....26.5429M. doi:10.1002/adma.201401356. PMID 24975272. S2CID 29645895.
- ↑ Mei, Ju; Leung, Nelson L. C.; Kwok, Ryan T. K.; Lam, Jacky W. Y.; Tang, Ben Zhong (22 October 2015). "Aggregation-Induced Emission: Together We Shine, United We Soar!". Chemical Reviews. 115 (21): 11718–11940. doi:10.1021/acs.chemrev.5b00263. PMID 26492387.
- ↑ Suzuki, Satoshi; Sasaki, Shunsuke; Sairi, Amir Sharidan; Iwai, Riki; Tang, Ben Zhong; Konishi, Gen-ichi (2020). "Principles of Aggregation-Induced Emission: Design of Deactivation Pathways for Advanced AIEgens and Applications". Angewandte Chemie International Edition. 59 (25): 9856–9867. doi:10.1002/anie.202000940. ISSN 1521-3773. PMC 7318703 . PMID 32154630.
- ↑ Jin, Yi; Xu, Yanbin; Liu, Yinling; Wang, Lingyun; Jiang, Huanfeng; Li, Xianjie; Cao, Derong (September 2011). "Synthesis of novel diketopyrrolopyrrole-based luminophores showing crystallization-induced emission enhancement properties". Dyes and Pigments. 90 (3): 311–318. doi:10.1016/j.dyepig.2011.01.005.
- ↑ Virk, Tarunpreet Singh; Ilawe, Niranjan V.; Zhang, Guoxian; Yu, Craig P.; Wong, Bryan M.; Chan, Julian M. W. (20 December 2016). "Sultam-Based Hetero[5]helicene: Synthesis, Structure, and Crystallization-Induced Emission Enhancement". ACS Omega. 1 (6): 1336–1342. doi:10.1021/acsomega.6b00335. PMC 6640820 . PMID 31457199.
- ↑ Moghadam, Fatemeh Mortazavi; Rahaie, Mahdi (May 2019). "A signal-on nanobiosensor for VEGF165 detection based on supraparticle copper nanoclusters formed on bivalent aptamer". Biosensors and Bioelectronics. 132: 186–195. doi:10.1016/j.bios.2019.02.046. PMID 30875630. S2CID 80613434.
- ↑ Mortazavi Moghadam, Fatemeh; Bigdeli, Mohammadreza; Tamayol, Ali; Shin, Su Ryon (October 2021). "TISS nanobiosensor for salivary cortisol measurement by aptamer Ag nanocluster SAIE supraparticle structure". Sensors and Actuators B: Chemical. 344: 130160. doi:10.1016/j.snb.2021.130160.
- ↑ Han, Ting; Deng, Haiqin; Qiu, Zijie; Zhao, Zheng; Zhang, Haoke; Zou, Hang; Leung, Nelson L. C.; Shan, Guogang; Elsegood, Mark R. J.; Lam, Jacky W. Y.; Tang, Ben Zhong (9 April 2018). "Facile Multicomponent Polymerizations toward Unconventional Luminescent Polymers with Readily Openable Small Heterocycles". Journal of the American Chemical Society. 140 (16): 5588–5598. doi:10.1021/jacs.8b01991. PMID 29630372. S2CID 207190130.
- ↑ Sun, Wenjing; Luo, Li; Feng, Yushuo; Cai, Yuting; Zhuang, Yixi; Xie, Rong-Jun; Chen, Xiaoyuan; Chen, Hongmin (5 September 2019). "Aggregation-Induced Emission Gold Clustoluminogens for Enhanced Low-Dose X-ray-Induced Photodynamic Therapy". Angewandte Chemie International Edition. 59 (25): 9914–9921. doi:10.1002/anie.201908712. PMID 31418982. S2CID 201020605.
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