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Stimuli-Regulated Cancer Theranostics Based on Magnetic Nanoparticles
Published in Nguyễn T. K. Thanh, Clinical Applications of Magnetic Nanoparticles, 2018
Yanmin Ju, Shiyan Tong, Yanglong Hou
As light can serve as a spatiotemporal trigger in controlled release, photoresponsive systems have been developed in the past few years to achieve on-demand drug release under the illumination of specific wavelength light by photosensitiveness-induced structural modifications of the nanocarriers. Azobenzene and its derivatives can change their structures from trans to cis under illumination of 300–380 nm wavelength light, and from cis to trans by irradiating light in the visible region, which can elicit photo-regulated release of drug. Many systems have been developed for the on-demand drug delivery by incorporating azobenzene to nanocarriers, including liposomes,138 micelles,139 or polymers.140 Suzuki et al. proposed micellar MRI contrast agents with photochromic molecule azobenzene derivative incorporated into the hydrophobic chain of DTPA-Gd derivative. These bifunctional micelles can release the included compound upon photoirradiation within 10 min, indicating that the platform is a potential MRI-traceable drug carrier that can be trigged by light.141
Photoresponsive Materials Containing Azomoieties—A Facile Approach In Molecular Imprinting
Published in A. K. Haghi, Devrim Balköse, Omari V. Mukbaniani, Andrew G. Mercader, Applied Chemistry and Chemical Engineering, 2017
T. Sajini, Beena Mathew, Sam John
Photoresponsive materials can be synthesized by functionalizing the material with photosensitive molecules such as cinnamic acid, cinnamylidene, or azo compounds. Out of these azobenzene is the most widely used photosensitive molecule due to its fast response on exposure to appropriate wavelength of light.8 Azobenzene molecules are known to change their geometry upon photon absorption. Azobenzene is composed of two aromatic rings, where an azo linkage ( - N = N - )joins the two phenyl rings.9 Different type of azo compounds can be obtained by substituting an aromatic ring with various substituents to change geometry and electron donating/withdrawing mechanism. The light‐induced configurational change renders azobenzenes good candidates for various photoresponsive applications. Due to their anisotropic shape, azobenzenes also contain directional information and are polarization sensitive. The phenomena arising from the photoisomerization reaction have applications not only in optics and photonics but also in the interfaces between light and surface science, information storage, imaging, biology, energy storage, and actuation.
Optical nano- and microactuation
Published in John P. Dakin, Robert G. W. Brown, Handbook of Optoelectronics, 2017
Kang et al. (2009) describes a light-driven single-molecule DNA hairpin-structured nanomotor that utilizes a photosensitive azobenzene molecule to induce movement (Figure 17.4). Azobenzene undergoes a reversible cis–trans isomerism when exposed to alternating UV and visible radiation. Note that the term cis means “on the same side” and trans means “on the other side.” When azobenzene is linked to other molecules then the switching mechanism can cause a relatively large dimensional change in the functionalized material. By controlling the azobenzene moieties integrated on the DNA bases in the hairpin’s duplex stem segment, it is possible to modify the dehybridization (open) and hybridization (closed) state of a hairpin structure and control movement. Since the open–close cycle of the hairpin molecule exhibits reversible extension and contraction behavior, it can be identified as a nanomotor. The photoregulation of this simple system is concentration-independent and, therefore, suitable for fabricating high-density molecular motors.
Effect of confinement on the electronic and optical properties of azobenzene: cucurbituril as a means of confinement
Published in Molecular Physics, 2022
Peaush Gangwar, Saurabh Singh Negi, Venkatnarayan Ramanathan, C. N. Ramachandran
Azobenzene is an aromatic molecule discovered in 1834 and gained wide attention as one of the pioneering colouring agents in textile industries. Later, the change of its configuration upon the irradiation of light was studied by G. S. Hartley [1–4]. Azobenzene and its derivatives are photosensitive and readily undergo the transition from trans to cis configuration and vice versa upon the irradiation of light. For example, on irradiating the light of wavelength 365 nm, the trans azobenzene isomerises to less stable cis azobenzene, and the reverse transformation occurs on irradiating light of wavelength 420 nm [5–7] The π→π* transition of trans azobenzene takes place in the ultraviolet (UV) region. On the other hand, there are two transitions viz. π→π* and n→π* for cis azobenzene leading to absorptions in the UV and visible regions, respectively. The reversibility of the transformation of configuration renders them as fascinating materials.
Langmuir and Langmuir–Blodgett films of aromatic amphiphiles
Published in Soft Materials, 2022
There are several examples of amphiphiles which incorporate the azobenzene moiety, an azo linkage (–N = N–) flanked by two phenyl rings, in the hydrophobic tail part (Scheme 2, Structure 4). Azobenzene-based compounds have been traditionally used as dyes and colorants for many textile-related applications.[101] Apart from this, one feature of the azobenzene moiety which is frequently exploited is the reversible trans-to-cis photoisomerization of the azo linkage (Scheme 3) which leads to changes in the geometry/structure of the molecules/materials containing these moieties and thereby their properties and applications.[102,103] Many researchers have made use of this aspect in the design of azobenzene-containing amphiphiles which are summarized in Chart 4 and their Langmuir/LB film properties in Table 4. These azobenzene amphiphiles are further divided into three sub-groups on the basis of the type of head-groups present – (a) Organic acid head-groups (b) Ammonium head-groups (c) nonionic head-groups.
Refractive Bessel lattice in azobenzene liquid crystal
Published in Journal of Modern Optics, 2018
Varsenik Nersesyan, Tigran Dadalyan, Jeroen Beeckman, Filip Beunis, Kristiaan Neyts, Rafael Drampyan
The specific feature of azobenzene molecules to change between isotropic and anisotropic shape under illumination by different wavelengths brings a variety of possibilities for photonics applications. Due to the periodic refractive index variation, the Bessel lattice in this material creates micro-structured waveguides in the direction of beam propagation. Therefore, azobenzene LCs can be interesting for light localization and optical soliton generation in structured LC media. The volume holographic lattices are promising also for generation of self-imaging and self-healing beams with 3D intensity voids along beam propagation (38) which can find utility for developments of optical trapping systems.