scholarly journals Controlled Synthesis of Up-Conversion NaYF4:Yb,Tm Nanoparticles for Drug Release under Near IR-Light Therapy

Biomedicines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1953
Author(s):  
Edelweiss Moyano Rodríguez ◽  
Miguel Gomez-Mendoza ◽  
Raúl Pérez-Ruiz ◽  
Beatriz Peñín ◽  
Diego Sampedro ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Thermal Treatment ◽  
Drug Release ◽  
Transient Absorption ◽  
Bond Cleavage ◽  
Blue Emission ◽  
Light Therapy ◽  
Transient Absorption Spectroscopy ◽  
Highly Efficient ◽  
Near Ir

Up-Conversion materials have received great attention in drug delivery applications in recent years. A specifically emerging field includes the development of strategies focusing on photon processes that promote the development of novel platforms for the efficient transport and the controlled release of drug molecules in the harsh microenvironment. Here, modified reaction time, thermal treatment, and pH conditions were controlled in the synthesis of NaYF4:Yb,Tm up-converted (UC) material to improve its photoluminescence properties. The best blue-emission performance was achieved for the UC3 sample prepared through 24 h-synthesis without thermal treatment at a pH of 5, which promotes the presence of the β-phase and smaller particle size. NaYF4:Yb,Tm has resulted in a highly efficient blue emitter material for light-driven drug release under near-IR wavelength. Thus, NaYF4:Yb,Tm up-converted material promotes the N-O bond cleavage of the oxime ester of Ciprofloxacin (prodrug) as a highly efficient photosensitized drug delivery process. HPLC chromatography and transient absorption spectroscopy measurements were performed to evaluate the drug release conversion rate. UC3 has resulted in a very stable and easily recovered material that can be used in several reaction cycles. This straightforward methodology can be extended to other drugs containing photoactive chromophores and is present as an alternative for drug release systems.

Charge delocalization of naphthalene cations formed in triad molecules studied by near-IR transient absorption spectroscopy

2003 ◽  
Vol 374 (1-2) ◽  
pp. 137-142 ◽  
Author(s):  
Hideo Ohkita ◽  
Toshiki Fushimi ◽  
Kunihiro Atsumi ◽  
Yusuke Fujita ◽  
Shinzaburo Ito ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Charge Delocalization ◽  
Near Ir

Ultrafast Transient Absorption Spectroscopy Investigations of Excited State Dynamics in SWNT/Polymer Composites

2004 ◽  
Vol 858 ◽  
Author(s):  
David J. Styers-Barnett ◽  
Steven P. Ellison ◽  
Cheol Park ◽  
Kristopher E. Wise ◽  
John M. Papanikolas
Keyword(s):  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Hot Electron ◽  
Plasmon Band ◽  
Near Ir ◽  
Spectral Shifts ◽  
Femtosecond Transient Absorption ◽  
Transient Spectra ◽  
Walled Carbon Nanotubes

ABSTRACTWavelength-resolved femtosecond transient absorption spectroscopy is used to follow the electronic dynamics of single-walled carbon nanotubes in polymers following visible and near IR photoexcitation. Electron-hole (e-h) pairs give rise to sharp features in the transient spectra that decay in amplitude and exhibit rapid spectral shifts. The decay reflects (e-h) recombination on both short (1.3 ps) and long (35 ps) time scales. Transient spectra also exhibit a broad photobleach at early times that arises from the cooling of a hot electron gas created via excitation at the red edge of a π-plasmon band.

scholarly journals Resolving photoisomerization dynamics via ultrafast UV-visible transient absorption spectroscopy

2021 ◽  
Author(s):  
◽  
Shyamal Prasad
Keyword(s):  
Absorption Spectroscopy ◽  
Ground State ◽  
Transient Absorption ◽  
Bond Cleavage ◽  
Ultra Violet ◽  
Solvent Polarity ◽  
Transient Absorption Spectroscopy ◽  
Bond Breakage ◽  
Solvent Dependence ◽  
Azobenzene Moiety

<p>Transient absorption spectroscopy has been employed to investigate three photo–active compounds; azobenzene, foldamer controlled by azobenzene, and oxazine. These compounds all have absorption in the ultra–violet regions responsible for their photo–active behavior. Due to this, the current transient absorption setup has been modified to extend the probing wavelength range to 320–650 nm, with the possibility of exciting the photo–active molecule in the ultra–violet.  Azobenzene is valuable in benchmarking and optimizing the transient absorption setup, it shows that the detection window has been extended out to 320 nm. By resolving the ground state bleach we have added support for the assignment of the final decay to thermalization in the ground state. Comparison of relaxation lifetime in acetonitrile and tetrahydrofuran shows no noticeable change in the photophysics of isomerization between the two solvents.  The foldamer family excited state relaxation is similar to azobenzene. There is an extension in the S₁ branching lifetime from 1.1 ps in azobenzene to 1.7 ps for foldamer 1 and 4.2 ps for foldamer 2. The separation of branching on the S₁ surface and relaxation through the S₁ to electronic ground state intersection was possible by comparison of azobenzene and foldamer family. The solvent effects show little difference for all members of the foldamer family expect for foldamer 2, suggesting that the dynamics of the azobenzene moiety are not affected by the larger macro–structure of the foldamer.  For oxazine it has been established, by varying solvent polarity, that isomerization happens through three states; bond breakage, transfer to a dark state, and the final photo–isomer. This is confirmed by further studies completed after the introduction of electron withdrawing fluorine atoms. Carbon–oxygen bond cleavage occurs on the picosecond timescale, with solvent dependent rotation occurring in hundreds of picoseconds. Fluorinated oxazine shows a strong solvent dependence with rotation suppressed for all but the most polar of solvents.</p>

scholarly journals Aggregation Controlled Charge Generation in Fullerene Based Bulk Heterojunction Polymer Solar Cells: Effect of Additive

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 115
Author(s):  
Washat Ware ◽  
Tia Wright ◽  
Yimin Mao ◽  
Shubo Han ◽  
Jessa Guffie ◽  
...  
Keyword(s):  
Solar Cells ◽  
Polymer Blends ◽  
Transient Absorption ◽  
Polymer Solar Cells ◽  
Acid Methyl Ester ◽  
Transient Absorption Spectroscopy ◽  
Generation Process ◽  
Charge Generation ◽  
Highly Efficient ◽  
The Impact

Optimization of charge generation in polymer blends is crucial for the fabrication of highly efficient polymer solar cells. While the impacts of the polymer chemical structure, energy alignment, and interface on charge generation have been well studied, not much is known about the impact of polymer aggregation on charge generation. Here, we studied the impact of aggregation on charge generation using transient absorption spectroscopy, neutron scattering, and atomic force microscopy. Our measurements indicate that the 1,8-diiodooctane additive can change the aggregation behavior of poly(benzodithiophene-alt-dithienyl difluorobenzotriazole (PBnDT-FTAZ) and phenyl-C61-butyric acid methyl ester (PCBM)polymer blends and impact the charge generation process. Our observations show that the charge generation can be optimized by tuning the aggregation in polymer blends, which can be beneficial for the design of highly efficient fullerene-based organic photovoltaic devices.

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