Sensitizer Molecules Research Articles

Sensitizer created defective metal organic framework as a new platform for boosting visible-light photocatalysis of g-C3N4

We developed herein for the first time a sensitizer created defective MOF (SCD-MOF), simultaneously possessing sensitizers and defects as visible-light harvester and electron trapper, respectively, which can synergistically improve the visible-light photocatalysis of polymeric graphitic carbon nitride (g-C3N4). Based on this discovery, the resulting 5.0 wt% FeTCPP⊂UiO-66@g-C3N4 shows a significant 6.6 and 3.9 times improvement in catalytic efficiency compared with its parent materials of FeTCPP⊂UiO-66 and g-C3N4 in degrading organic pollutants. Moreover, it shows a 10.4 times enhancement in catalytic efficiency compared with commercial TiO2 (P25). Mechanism studies suggest that sensitizer molecules and defects in SCD-MOF can synergistically improve photocatalytic efficiency because of broadening the visible-light response and strengthening the charge carrier separation. This work illustrates a remarkably triple synergetic effect among visible-light harvester, electron/hole separator, and semiconductor and thus established SCD-MOF as a class of new platform to greatly improve the visible-light photocatalytic performance of conventional semiconductors.

Graphite counter electrode modified Tropaeolin‐O photo‐sensitized photogalvanic cells for solar power and storage

AbstractAn optimization, photo‐stability, and hysteresis property of the Graphite counter electrode‐modified Tropaeolin‐O (TPO) photo‐sensitized photogalvanic (PG) cells has been investigated. A complex H‐shaped cell design, a costly and delicate saturated calomel electrode (counter electrode), and a heavy sensitizer molecule (dye having high molecular weight, low diffusivity, and low photo‐stability) have been exploited for fabricating most of the PG cells so far. All these factors are not suitable for the fabrication of durable and cheap PG cells. Therefore, in the present study, the highly conductive/catalytically active robust graphite electrode with TPO dye photosensitizer (having a low molecular weight, higher diffusivity, and higher photo‐stability) has been exploited with diffusion‐friendly low cost and a simple transparent cylindrical glass tube. The cheap and robust graphite counter electrode has been exploited for optimization and long‐term study of the TPO photo‐sensitized PG cells. The observed electrical output is potential 676 mV, current 2000 µA, and power 340.0 μW. The power, current, and efficiency, have been found quite independent of the illumination window size. The potential and current have been observed to be quite stable over a long time during illumination, and the same has been supported by the hysteresis study.

An optimal analytical study on a solar photovoltaic system with different rates of absorbed photon and emitted electron

This article aims to investigate the performance of a renewable energy system that includes solar cells with sensitizer molecules. The relevant problem of this photovoltaic technology is expressed as a system of differential equations and is solved using an optimal analytical method. To validate the solutions obtained from the applied technique, the results were compared with previous works, which showed a very good agreement. For more physical analysis, the influence of different values of emitted, transmitted, and trapped electrons as well as the absorbed photons on the present solar cell system are evaluated comprehensively. The results showed that with the increase of the absorbed photon rate from one to three, the thickness of the sensitized dye increases by about 7 times (at t = 1s). It can also be seen from the obtained results that as the electron emission rate increases from 2 to 4, the thickness of the anode decreases by almost 14 % (at t = 6s).

Potential Applications of Nanoparticles in Improving the Outcome of Lung Cancer Treatment.

Lung cancer is managed using conventional therapies, including chemotherapy, radiation therapy, or a combination of both. Each of these therapies has its own limitations, such as the indiscriminate killing of normal as well as cancer cells, the solubility of the chemotherapeutic drugs, rapid clearance of the drugs from circulation before reaching the tumor site, the resistance of cancer cells to radiation, and over-sensitization of normal cells to radiation. Other treatment modalities include gene therapy, immunological checkpoint inhibitors, drug repurposing, and in situ cryo-immune engineering (ICIE) strategy. Nanotechnology has come to the rescue to overcome many shortfalls of conventional therapies. Some of the nano-formulated chemotherapeutic drugs, as well as nanoparticles and nanostructures with surface modifications, have been used for effective cancer cell killing and radio sensitization, respectively. Nano-enabled drug delivery systems act as cargo to deliver the sensitizer molecules specifically to the tumor cells, thereby enabling the radiation therapy to be more effective. In this review, we have discussed the different conventional chemotherapies and radiation therapies used for inhibiting lung cancer. We have also discussed the improvement in chemotherapy and radiation sensitization using nanoparticles.

Chitosan-coated iron oxide nanoparticles obtained by laser pyrolysis

The structural and magnetic properties of iron oxide nanoparticles (NPs) synthesized by laser pyrolysis, as well as their chitosan-stabilized aqueous suspensions were studied in regards to the ratio between O2 and Ar. During the synthesis, the flow of Fe(CO)5 precursor vapors and C2H4 sensitizer molecules was kept constant, while the ratio between O2 and Ar in the reactive mixture was increased (1:4, 1:2, 1:1, and 2:1). The formation of small particles (under 4 nm in size) was observed at lower O2 concentrations, whereas their mean crystallite size increased to ∼14 nm for those formed from the richest O2 content, which also induced the formation of particles with the highest magnetization saturation (101.4 emu/g). Maghemite and/or magnetite phases were identified as the main components in all samples, while a small amount of α iron/iron carbides presence was detected with the exception of sample obtained at 1:1 O2 to Ar ratio. The formation of these minor phases reveals the interplay between oxidative and reductive processes which depend on O2 content and C2H4 reactivity at different temperatures. After chitosan loading, all aqueous suspensions presented excellent stability (zeta potential values over 76 mV). Moreover, the samples stabilized using low polymer concentration (0.05 g/l) displayed relatively low hydrodynamic sizes (110–125 nm).

Novel Metal Complexes Unit of Phenanthroline Derivative for Being Used as Auxiliary Electron Acceptor in Dye Sensitizer Molecules

AbstractDonor‐acceptor‐π bridge‐acceptor (D−A−π−A) motif dyes are promising dye sensitizers in dye‐sensitized solar cells (DSSCs). In this study, to strengthen with‐drawing electron force of the auxiliary electron acceptors(A) in D−A−π−A motif dye sensitizers, the metal complexes unit is be used as auxiliary electron acceptor(A) instead of organic electron‐withdrawing monomer. The four polymeric metal complexes were designed, synthesized, and characterized, which used metal complexes of phenanthroline derivatives as auxiliary acceptors (A), benzodithiophene‐dithiophene derivatives (BDTT) as donors (D), and 8‐hydroxyquinoline derivatives as π‐bridges and acceptors of the dye sensitizers, and have been used for dye sensitizers. Under AM 1.5 G (100 mW cm−2), the photovoltaic test results indicated that the short‐circuit photocurrent density (Jsc) of the DSSCs based four polymeric metal complexes are 11.26, 13.68, 14.42 and 15.57 mA cm−2and power conversion efficiency (PCE) are 5.96 %, 7.83 %, 8.07 %, 9.28 % respectively. BothJscandPCEvalue of the four polymeric metal complexes increased in order. This may be due to the fact that larger radius of metal ion under the same change number can enhance the coordination bond and cause stronger electron‐withdrawing ability of auxiliary acceptor and stronger charge‐transfer ability between the donor and the acceptor, which results in higherJscand higherPCEof the polymeric complex dye sensitizer.

Water-Stable Upconverting Coordination Polymer Nanoparticles for Transparent Films and Anticounterfeiting Patterns with Air-Stable Upconversion.

Photon upconversion (UC) based on triplet-triplet annihilation is a very promising phenomenon with potential application in several areas, though, due to the intrinsic mechanism, the achievement of diffusion-limited solid materials with air-stable UC is still a challenge. Herein, we report UC coordination polymer nanoparticles (CPNs) combining sensitizer and emitter molecules especially designed with alkyl spacers that promote the amorphous character. Beyond the characteristic constraints of crystalline MOFs, amorphous CPNs facilitate high dye density and flexible ratio tunability. To show the universality of the approach, two types of UC-CPNs are reported, exhibiting highly photostable UC in two different visible spectral regions. Given their nanoscale, narrow size distribution, and good chemical/colloidal stability in water, the CPNs were also successfully printed as anticounterfeiting patterns and used to make highly transparent and photostable films for luminescent solar concentrators, both showing air-stable UC.

High performance solution-processed red phosphorescent organic light-emitting diodes by co-doping europium complex as sensitizer

In this work, efficient red phosphorescent OLEDs (PHOLEDs) were designed and fabricated by solution processing method. Based on well optimized doping concentrations of emitter and ratio of mixed host materials, Eu(DBM) 3 Phen (DBM = 1,3-diphenylpropane-1,3-dion, Phen = 1,10-phenonthroline) was doped into the light-emitting layer (EML) which plays the role of sensitizer. Experimental results indicated that the incorporation of Eu(DBM) 3 Phen molecules can effectively trap the superfluous electrons within EML, which is helpful for balancing charges’ distribution and widening the recombination zone. Besides, the presence of Eu(DBM) 3 Phen molecules can accelerate the transfer of triplet energy from hosts to red emitters, therefore remarkably enhances device performance. By optimizing the doping concentrations of emitter and sensitizer, ratio of co-hosts and the functional layer thickness, recombination center was accurately adjusted to further broaden recombination zone, therefore causing decreased excitons density and suppressed excitons quenching. Eventually, the optimal solution-processed red PHOLED obtained the maximum current efficiency (47.12 cd/A) and external quantum efficiency (27.3%). High performance solution-processed red phosphorescent organic light-emitting diodes by incorporating trivalent rare earth europium complex Eu(DBM) 3 Phen (DBM = 1,3-diphenylpropane-1,3-dion, Phen = 1,10-phenonthroline) into light-emitting layer as sensitizer. • High performance solution-processed red phosphorescent OLED was designed by utilizing trivalent rare earth europium complex Eu(DBM) 3 Phen into light-emitting layer as sensitizer. • Co-doped sensitizer molecules function as electron trappers, which is helpful in balancing carriers' distribution and broadening recombination zone. • The optimal solution-processed red PHOLED obtained the maximum current efficiency up to 47.12 cd/A and external quantum efficiency up to 27.3%. • This work firstly demonstrated the efficacy of utilizing rare earth complex as sensitizer in realizing high performance solution-processed OLEDs.

Interfacial effects on sensitization of chemically amplified extreme ultraviolet resists

With the improvement of lithography resolution in the horizontal direction, the thickness of resist films becomes thin to avoid pattern collapse. The thinning of resist films is an important issue in the development of the next-generation lithography process. In this study, the interfacial effects on the sensitization of chemically amplified extreme ultraviolet (EUV) resists were investigated using a Monte Carlo method on the basis of their sensitization mechanism. The chemically amplified resist is a standard resist used for the fabrication of semiconductor devices. In chemically amplified resists, thermalized electrons reduce sensitizer molecules upon exposure to EUV radiation. The low-energy secondary electron dynamics at the vacuum-resist and resist-underlayer interfaces strongly affected the distribution of decomposed sensitizers. In particular, the resist bulk layer almost disappeared at 20 nm pitch in the specific cases. The control of interfaces becomes important in the development of the next-generation lithography process.

Tropaeline O‐oxalic acid‐benzalkonium chloride photogalvanic cells for solar energy conversion and storage

AbstractThe photogalvanic (PG) cells involve a change in the electrode potential by photochemical processes along with the diffusion of ionic species through the bulk electrolyte. The PG cells have used so far the complex H‐shaped cell design, heavy sensitizer molecules with low diffusivity, and low photo‐stability. All these factors are not conducive to the fabrication of cheap cells with good electrical output. To address all these concerns, the tropaeline‐O dye photosensitizer (a low molecular weight molecule with higher diffusion and higher photo‐stability) has been exploited with diffusion‐friendly low cost and a simple transparent cylindrical glass tube. The optimum values of the cell's electrical parameters are: potential 998 mV, current 3200 µA, and power 829.5 µW, and it is quite similar at all illumination window sizes.

Fully Programmable Collective Behavior of Light‐Powered Chemical Microrobotics: pH‐Dependent Motion Behavior Switch and Controlled Cancer Cell Destruction

AbstractThe development of fuel‐free light‐powered multi stimuli‐responsive microrobots is becoming a vital field in biomedical research. The challenge is to design biomedical robots with precise motion control and novel functionalities such that one day they will stand alongside medical staff as fully fledged partners in the delivery of advanced non‐invasive therapeutic procedures. In this study, a simple one‐step etching/polymerization procedure is used to fabricate crystalline metal‐organic framework structures surface‐coated with a conductive polypyrrole (PPy) layer and then enriched with Methylene Blue sensitizer molecules. Due to the PPy surface charge, the microrobots start to move when exposed to a visible light source, enabling the controllable accumulation of the microrobots at the focal point of the light beam. Furthermore, a self‐regulated motion is achieved by the PPy surface charge also providing a pH‐dependent switch capable of altering microrobot behavior. In vitro study is conducted to test microrobot efficiency against human cervix carcinoma HeLa cells. It is shown that the micromotors are able to penetrate and successfully destroy the cancer cells. The work provides proof‐of‐concept for a novel strategy in which such microrobots can be guided by an optical beam, can self‐regulate movement toward or away from each other, and can perform therapeutic functions with great efficiency.

Properties of Chlorophyll Based Organic Dye Sensitizer Molecule Extracted in Various Solvents

Properties of Chlorophyll Based Organic Dye Sensitizer Molecule Extracted in Various Solvents

Effects of the phosphorescent sensitizer on charge dynamics in deep blue phosphor-sensitized-fluorescent organic light-emitting diodes

In phosphor-sensitized-fluorescent organic light-emitting diodes (PSF-OLEDs), triplet excitons generated in the emitting layer (EML) are harvested by the sensitizer and the excitonic energy is efficiently transferred to the fluorescent dopant molecules. Since a phosphorescent sensitizer is typically doped at around 10 wt.%, the sensitizer not only affects cascade energy transfer but also electrical transporting in the PSF-OLEDs. However, the electrical role of phosphorescent metal complex molecules in the EML is unclear. In this study, we report the impact of the phosphorescent sensitizer on the electrical properties of PSF-OLEDs. Through a comprehensive analysis using impedance spectroscopy in conjunction with current density (J)-voltage (V)-luminance (L) properties of the PSF-OLED, it was revealed that 10 wt.% phosphorescent sensitizer forms an electron transporting pathway inside the EML. Thus, the sensitizer molecules transform a unipolar single host into a bipolar mixed host. In other words, the phosphorescent sensitizer is an n-type host in the PSF-OLEDs. As a result, the charge balance and the operating voltage were simultaneously and significantly improved in the PSF-OLEDs.

Fabrication of Functional Materials for Dye-sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) have been developed as a promising photovoltaic cell type in recent decades because of their low cost, environmental friendliness, ease of fabrication, and suitability for a wide range of indoor and outdoor applications, especially under diverse shaded and low-light condition. They are typically composed of three main components: a transparent conducting oxide (TCO) substrate-based working electrode with wide-bandgap semiconductors and dye sensitizer molecules, an electrolytic mediator based on redox couple species, and a TCO-based counter electrode consisting of catalyst materials. The development of intrinsic and functional organic, inorganic, metal oxide, composite, and carbon-based materials has been intensively studied to enhance the efficiency of DSSCs. A simple and low-cost fabrication process that uses natural products is also considered essential for further large-scale production. In this article, we review the fabrication of various functional materials and their effects on DSSC performance.

Impact of TiO2 Nanostructures on Dye-Sensitized Solar Cells Performance.

The effect of TiO2 nanostructures such as nanoparticles, nanowires, nanotubes on photoanode properties, and dye-sensitized solar cells photovoltaic parameters were studied. The series of dye-sensitized solar cells based on two dyes, that is, commercially N719 and synthesized 3,7′-bis(2-cyano-1-acrylic acid)-10-ethyl-phenothiazine were tested. Additionally, the devices containing a mixture of this sensitizer and chenodeoxycholic acid as co-adsorbent were fabricated. The amount of adsorbed dye molecules to TiO2 was evaluated. The prepared photoanodes with different TiO2 nanostructures were investigated using UV-Vis spectroscopy, optical, atomic force, and scanning electron microscopes. Photovoltaic response of constructed devices was examined based on current-voltage characteristics and electrochemical impedance spectroscopy measurements. It was found that the highest UV-Vis absorption exhibited the photoanode with nanotubes addition. This indicates the highest number of sensitizer molecules anchored to the titanium dioxide photoanode, which was subsequently confirmed by dye-loading tests. The highest power conversion efficiency was (6.97%) for solar cell containing nanotubes and a mixture of the dyes with a co-adsorbent.

Adiponectin-expressing Treg facilitate T lymphocyte development in thymic nurse cell complexes

Adiponectin is a well-known insulin sensitizer and anti-inflammatory molecule, possessing therapeutic potentials in cardiovascular, metabolic and cancer diseases. Results of the present study demonstrate that adiponectin is expressed in a population of regulatory T-cells (Treg) resided within the thymic nurse cell (TNC) complexes. Adoptive transfer of adiponectin-expressing Treg precursors effectively attenuated obesity, improved glucose and insulin tolerance, prevented fatty liver injuries in wild-type mice fed a high-fat diet, and significantly inhibited breast cancer development in MMTV-PyVT transgenic mice. Within the TNC complexes, locally produced adiponectin bound to and regulated the expression as well as the distribution of CD100, a transmembrane lymphocyte semaphorin, in turn modulating the lymphoepithelial interactions to facilitate T-cell development and maturation. In summary, adiponectin plays an important role in the selection and development of T lymphocytes within the TNC complexes. Adiponectin-expressing Treg represent a promising candidate for adoptive cell immunotherapy against obesity-related metabolic and cancer diseases.

Photocatalytic and photosensitization reactions of surface modified W6+ and N3‒ doped TiO2 with curcumin/potassium curcuminate molecules

Curcumin and potassium curcuminate molecules were anchored on W6+ and N3‒ doped TiO2 catalyst (WNT) surface by wet impregnation method and were designated as Cur-WNT and K3Cur-WNT. The XPS and FTIR techniques confirm the surface anchoring of curcumin and potassium curcuminate molecules on the surface of WNT through enolate linkage. K3Cur-WNT catalyst possesses multiple charge trapping states involving dopant energy levels, inherently created defect levels/surface states. Hence the mean free path of the photogenerated electrons is decreased in this catalyst by trapping and detrapping events. The energy band positions of valence band (EVB), conduction band (ECB) and Fermi energy (EF) were determined from the electronegativity values of the atoms present in the catalyst sample and also from the valence band X-ray photoelectron spectroscopic (VBXPS) studies. Energetically the position of conduction band (CB) and W 5d dopant energy levels were found to be located below the lowest unoccupied molecular orbital (LUMO) of curcumin and potassium curcuminate molecules in Cur-WNT and K3Cur-WNT samples. This suitable excited singlet energy band position (S1) of sensitizer molecule facilitates the electron transfer process to the CB/W 5d energy levels of the WNT catalyst. The accumulated electrons in CB/W6+ dopant energy level influence the position of EF within the band gap. The observed higher quantum efficiency of K3Cur-WNT sample compared to all the other catalysts can be accounted to the narrowed band gap, generated shallow traps, reduced particle size, enhanced photosensitivity and its higher capability in generating reactive singlet oxygen species.

Energy transfer from high electronic levels of sensitizer molecules in bacterial solutions

The population dynamics of different energy states of sensitizer molecules under intense laser irradiation was studied taking account of triplet-triplet absorption and intersystem crossing between highly excited states. It is shown which quantum states are predominantly populated under the given irradiation conditions. It was found that the efficiency of energy transfer from high electronic levels of xanthene dyes in the media containing Escherichia coli or Bacillus subtilis bacteria is very low and this bacteria inactivation channel can be ignored when describing the mechanisms of damage to pathogenic microorganisms in the presence of photosensitizers.

Modulation of Mitochondrial Quality Control Processes by BGP-15 in Oxidative Stress Scenarios: From Cell Culture to Heart Failure.

Heart failure (HF) is a complex chronic clinical disease characterized by among others the damage of the mitochondrial network. The disruption of the mitochondrial quality control and the imbalance in fusion-fission processes lead to a lack of energy supply and, finally, to cell death. BGP-15 (O-[3-piperidino-2-hydroxy-1-propyl]-nicotinic acid amidoxime dihydrochloride) is an insulin sensitizer molecule and has a cytoprotective effect in a wide variety of experimental models. In our recent work, we aimed to clarify the mitochondrial protective effects of BGP-15 in a hypertension-induced heart failure model and “in vitro.” Spontaneously hypertensive rats (SHRs) received BGP-15 or placebo for 18 weeks. BGP-15 treatment preserved the normal mitochondrial ultrastructure and enhanced the mitochondrial fusion. Neonatal rat cardiomyocytes (NRCMs) were stressed by hydrogen-peroxide. BGP-15 treatment inhibited the mitochondrial fission processes, promoted mitochondrial fusion, maintained the integrity of the mitochondrial genome, and moreover enhanced the de novo biogenesis of the mitochondria. As a result of these effects, BGP-15 treatment also supports the maintenance of mitochondrial function through the preservation of the mitochondrial structure during hydrogen peroxide-induced oxidative stress as well as in an “in vivo” heart failure model. It offers the possibility, which pharmacological modulation of mitochondrial quality control under oxidative stress could be a novel therapeutic approach in heart failure.

The influence of the shape and configuration of sensitizer molecules on the efficiency of DSSCs: a theoretical insight.

The sensitizer is an active component of dye sensitized solar cell (DSSC) technology, which is highly influential for the performance of DSSCs. The present study attempts to investigate the relationship between the shape of the sensitizer molecule and efficiency of DSSCs. Specifically, 17 different structures were investigated, and classified into four categories based on the shape of the dye molecule, namely L-shaped (linear), V-shaped, X-shaped and Y-shaped, and into two different categories based on the donor moiety. The five of studied structures contained a triphenylamine (TPA) donor moiety, and twelve structures contained carbazole (CAR) donor moiety. Parameters related to the performance of DSSCs such as absorption spectra, intramolecular charge transfer indices, frontier molecular orbitals, light harvesting efficiency, excited-state lifetime, exciton binding energy, electrostatic potential, charge transfer and electron injection ability were studied using results obtained from electronic structure calculations. The analysis of these various parameters showed that the linear-shaped and V-shaped sensitizers possess better photon absorption ability, and the V-shaped structure is best suited shape for applications in high performance DSSCs.