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Organic Materials for Third-Order Nonlinear Optics
Published in Hari Singh Nalwa, Seizo Miyata, Nonlinear Optics of Organic Molecules and Polymers, 2020
All-trans"-carotene has 11 conjugated double bonds and represents a good model system of onedimensional polyenes. All-trans"-carotene has been extensively investigated for third-order nonlinear optics and its ?(3)and y values have been measured over a wide wavelength range covering the entire absorption spectral region. The ?(3)and y values of all-trans"-carotene vary by several orders of magnitude depending on the measurement wavelength, material state, and techniques as summarized in Table 27. The ?3)value as high as 1.6 X 10"10 esu and y value as high as 10~31 esu at the peak of the l'Bu resonance have been determined for all-trans"-carotene. The magnitude of ?(3)and y values is of the same order as that reported for polydiacetylenes. Ticktin191 reported dispersion of the ?(3)value of all-trans"-carotene-doped PMMA thin films in the region 1.2 ~ 2.0 ?m using OPO- THG measurements. The ?(3)of all-trans"-carotene-doped PMMA thin films followed the absorption spectrum, and the measured resonant ?3)value was more than 2 X 10 11 esu at 1.4 ?m, about 10 times larger than at 2.0 ?m in the off-resonance region, van Beek et al.215-217 studied the dispersion of the ?(3)value of all-trans"-carotene-doped polystyrene thin films. The magnitude of the ?(3)value of all-trans"-carotene-doped polystyrene thin films was 1.6 X ICT10 esu at the peak of the 1 *BU resonance. The absorption peak at around 460 nm corresponds to a *BU excited state. The ?(3)value of an all-trans "-carotene in the 400 to 550 nm region can be explained by l*Ag ground state, the I1 Bu excited state and an n'Ag excited state. The dipole transition moment of 31 D was determined between the l'Bu excited state and the n'Ag excited state around 22,200 cm-1. The molecular excitations of all-trans"- carotene are similar to those in poly acetylenes and should exhibit similar effects.
Design and in vitro antifungal activity of Nystatin loaded chitosan-coated magnetite nanoparticles for targeted therapy
Published in Inorganic and Nano-Metal Chemistry, 2021
Kamiar Zomorodian, Hamed Veisi, Somayeh Yazdanpanah, Sajad Najafi, Aida Iraji, Saba Hemmati, Bikash Karmakar, Hojat Veisi
Nystatin, the first antifungal agent belonging to the polyene polyhydroxy group, exhibits good activity against Candida species. While concerned about the mode of action, it is proposed that Nystatin acts as an ionophore, binds with the ergosterol, a major component of the fungal cell membrane, and subsequently forms pores on the membrane to leak out K+ ions, which ultimately results in the death of the affected cell. Since Nystatin is a highly non-polar compound and insoluble in water, it is not absorbed by the gastrointestinal tract during oral administration.[18] Despite the high toxicity of Nystatin, it is still prescribed for the treatment of oropharyngeal candidiasis and cutaneous aspergillosis in high-risk populations.[19] Despite its outstanding antifungal and fungicidal properties, Nystatin has no systemic administration and is solely used to treat mucocutaneous fungal infections.[20] Furthermore, mucosal circulation affects its efficacy, resulting in fast drug exertion from body surfaces. To overcome this issue, loading Nystatin onto biocompatible iron nanoparticles might result in improvement of its effectiveness through target therapy with magnetic fields.
Charge migration engineered by localisation: electron-nuclear dynamics in polyenes and glycine
Published in Molecular Physics, 2018
Iakov Polyak, Andrew J. Jenkins, Morgane Vacher, Marine E. F. Bouduban, Michael J. Bearpark, Michael A. Robb
In a longer chain containing five chromophores, charge migration exhibits a more complex pattern due to a larger number of eigenstates contributing to the electronic wave packet. Let us first discuss the frozen-geometry case (Figure 7). When the central double bond (NBO-1) is ionised, eigenstates 1, 3 and 5 get populated (at least at the symmetric equilibrium geometry, see Table 2), amounting roughly to the two energy gaps of 2.5 and 5 eV (with the smaller energy difference contributing twice), giving periods of oscillation of roughly 1.6 and 0.8 fs. Since one period is approximately twice the other, prior to dephasing, we expect to see a full constructive interference at multiples of 1.6 fs and only partially constructive interference at multiples of 0.8 fs. Indeed, larger peaks of spin density at C5 alternate with smaller intermediate peaks at roughly the estimated times (Figure 7(a)). Oscillation patterns at the C3 and C1 atoms are smoother (Figure 7(b,c)), with each plot vividly reflecting only one of the oscillation frequencies. Having fitted the average spin density oscillation at C3 to a model function, the dephasing half-life could be estimated to be 3.6 fs. When other than the central double bond gets ionised (see Figure 7(d–f) for NBO-2 and Figure 7(g–i) for NBO-3 ionisation), more complex patterns can be observed since up to five eigenstates now contribute to the electronic wave packet (see Table 2), resulting in more oscillation frequencies. One can assume that the averaged spin density signals at C3 with NBO-1 being ionised (Figure 7(b)) and at C5 with NBO-2 being ionised (Figure 7(e)) are expected to be the most representative results to be potentially observed in the experiment for an arbitrary-sized polyene due to being associated with non-terminal atoms in a situation when a non-terminal double bond is ionised (with the corresponding periods of oscillation being apparently related to the energy spacing between the lowest and highest-energy eigenstates forming the wave packet).
Nasal mucoadhesive in situ gelling liquid crystalline fluid precursor system of polyene antibiotic for potential treatment of localized sinuses aspergillosis post COVID infection
Published in Journal of Dispersion Science and Technology, 2023
Marzooka Kazi-Chishti, Javeed Shaikh, Nazimuddin Chishti, Mohamed Hassan Dehghan
Nystatin (NYS) a broad spectrum polyene macrolide antifungal antibiotic is a BCS class IV drug.[21] It offers activity against various fungal species such as Candida spp.,[22]Aspergillus,[23]Cryptococcus spp.,[24]Histoplasma spp.,[25]Blastomyces spp.,[26] and Microsporum spp.[27] The first line drugs used in the treatment of aspergillosis is Voriconazole and Amphotrecein B or in combination. With increased occurrence of COVID, influenza viral pneumonitis, or bacterial co-infection were respiratory failure, sepsis, and multi-organ failure can cumulate to death is found to be associated with Aspergillus infection. Morevover emerging trends of Aspergillus fumigatus resistant to voriconazole, itraconazole, posaconazole, and amphotrecein B has been reported in the U.S.[21,28–30] leading to infections with this strain even harder to treat. Nystatin a very older drug is highly efficient against azole resistant and amphotericin B resistant strains of Candida albicans and Aspergillus fumigates.[21,31,32] The topical delivery of NYS has been applied in treatment of oropharyngeal, cutaneous and vaginal fungal infections owning to its considerable merits over systemic ingestion (either intravenous or oral) such as averting of systemic and infusion-related toxicities. However recent studies related with nystatin liposome formulations for intravenous administration have manifested significant reduction in toxicity with preservation of antifungal activity, thus opening avenues for its safe use in systemic and localized infections in refractory conditions.[31] The potential of NYS lipidic delivery approach has not been explored for localized treatment of sinusitis aspergillosis, this is the foremost attempt.