Platinum Octaethylporphyrin Research Articles

Study on the High Functional Contact Lens Material with Superior Oxygen Transmissibility and Antibacterial Properties.

The silicone monomer (SiH2) used in this study contains acrylate monomer, DMA (n,n-dimethylacrylamide). For the polymerization, PtOEP (platinum octaethylporphyrin) was added to the synthesized silicone, DMA (n,n-dimethyl acrylamide), HPMA (hydroxy propyl methacrylate), PEGMEMA [poly(ethylene glycol) methyl ether methylacrylate], EGDMA (ethylene glycol dimethacrylate) and the initiator AIBN (azobisisobutyronitrile) with various concentrations. Using the polymer produced through the thermal polymerization process, the optical and physical characteristics of high performance silicone hydrogel lenses were measured. The water content of sample containing PtOEP was in the range of 65.21∼66.56%. And also, oxygen permeability (Dk) of sample containing PtOEP was in the range of 30.20∼30.85 × 10-11 cm²/sec × mlO₂/ml × mmHg. In case of the sample with nanoparticle, the oxygen permeability was higher than that of Ref. sample without nanoparticle. Silicone hydrogel monomer containing PtOEP was expected to be used usefully as a material for red tinted chromagen optical lens with high oxygen permeability for color amblyopia.

Preparation and Characterization of Functional Ophthalmic Polymer Containing Nanoparticles Using Heat Treatment Method After Polymerization

The functional hydrogel lens containing HEMA (2-hydroxyethylmethacrylate) was manufactured by thermal polymerization and heat treatment method after room temperature polymerization, respectively. In this study, HEMA, EGDMA (ethylene glycol dimethacrylate) and the initiator AIBN (azobisisobutyronitrile) were used for thermal copolymerization and the mixture was heated at 100 °C for 1 hour. And also, HEMA, EGDMA, the initiator and distilled water were used for heat treatment method after room temperature copolymerization and the mixture was heated 80 °C for 1 hour and then treated at 100 °C for 1 hour to produce the hydrogel ophthalmic lens by cast mold method. To make the functional hydrogel lens, ZnPC and platinum octaethyl porphyrin were used as additives. The measurements of the physical characteristics of the copolymerized material showed that refractive index and contact angle of sample was in the range of 1.4010∼1.4585 and 21.46∼87.28°, respectively. In case of heat treatment method after room temperature copolymerization, the refractive index and wettability of sample was higher than that of thermal polymerization. And also, the addition of ZnPC nanoparticles allowed the hydrogel lens to block UV-light. The absorbance value of solution in which the lens prepared by the heat treatment method was immersed were much lower than that of thermal polymerization, so it can be judged that the stabilization of produced polymer maintained well. Based on the results of this study, the produced optical lens can be considered to satisfy the basic requirements of optical lens and can be used effectively as an additive for functional ophthalmic lens material with high refractive index and wettability.

Oxygen-sensing properties of a highly sensitive and anti-photo-bleaching fluoropolymer film

In this study, PtOEP/poly(p-FSt-co-TFEMA) fluoropolymer film based on the dynamic fluorescence quenching mechanism was prepared by embedded platinum octaethylporphyrin (PtOEP) in poly (p-fluorostyrene-co-trifluoroethyl methacrylate) (poly(p-FSt-co-TFEMA)) film via solvent evaporation method. The oxygen-sensing properties, including the sensitivity, fluorescence intensity, and photo-stability, were evaluated based on variable indicator concentration and film thickness. The optimal parameters were determined through a series of parallel experiments. Results indicate a film thickness of 16 μm and an optimal PtOEP concentration of 1.0 mM. Under optimal conditions, the PtOEP/poly(p-FSt-co-TFEMA) fluoropolymer film exhibited an adequate signal-to noise ratio, high oxygen sensitivity and satisfactory anti-photo-bleaching ability.

Preparation and application of ratiometric polystyrene-based microspheres as oxygen sensors

Mono-dispersed polystyrene-based microspheres with diameters about 1 μm encapsulating rhodamine moieties as oxygen insensitive internal reference probes and platinum octaethylporphyrin units as oxygen sensitive probes were synthesized as new ratiometric oxygen sensors (Rhod-PtOEP-PS). The dual luminophors of rhodamines and platinum porphyrin moieties exhibited emissions maxima at 585 nm and 644 nm, respectively. The microspheres showed good oxygen sensing properties in different oxygen partial pressures (pO2) and dissolved oxygen (DO) concentrations. It was found the oxygen probes and reference probes in microspheres showed higher photo-stability than their corresponding free fluorophores in solution. The microspheres also showed good sensitivity for air-pressure and cellular oxygen in cell culture medium. These microspheres were used to detect DOs in a few kinds of liquids including some daily drinks and it was found the measured errors were within positive/negative 11% as compared with the measured results using traditional oxygen electrodes.

TIPS-anthracene: a singlet fission or triplet fusion material?

Triisopropylsilylethynyl-substituted acenes (TIPS-acenes) have received prominent attention in the field of singlet fission, the pentacene derivative being an exothermic singlet fission material, and the tetracene being a prototypical endothermic material. Little attention has been given to TIPS-anthracene, which is expected to exhibit exothermic triplet–triplet annihilation, despite literature reports to the contrary. We show that there is some evidence for singlet fission in TIPS-anthracene solutions, and that it does exhibit triplet–triplet annihilation. We apply anti-Stokes action spectroscopy to determine the upconversion efficiency of a composition of TIPS-anthracene and platinum octaethylporphyrin. At a bias equivalent to 0.86 suns, the composition exhibited an annihilation efficiency of 3.2%, which may be compared to diphenylanthracene, which yielded 9.2% under the same conditions. We attribute the low efficiency to a combination of a shorter triplet lifetime and low lying T2 and T3 states. The results are supported by ab initio quantum chemical calculations.

Performances and impedance spectroscopy of Small-molecule bulk heterojunction solar cells based on PtOEP: PCBM

Small-molecule bulk heterojunction (SBHJ) solar cells based on platinum octaethylporphyrin (PtOEP) as donor material and phenyl-C61-butyric acid methyl ester (PCBM) as the acceptor were fabricated using spin coating techniques with weight ratios from 1:0.1 to 1:9. The formation of charge transfer complex CTC in the PtOEP: PCBM blend was specified from the redshift of the PtOEP absorption peak after blending with PCBM. The photovoltaic performance for PtOEP: PCBM blends were investigated using the external quantum efficiency (EQE) besides the current density–voltage (J–V) characteristics under illumination100 mW/cm2 (AM1.5G). The BHJ solar cell with PtOEP: PCBM ratio of 1:9 exhibited the best performance. The impedance spectroscopy (IS) was examined in the frequency range from 25 Hz to 1 MHz. The equivalent circuit model was evaluated in details to evaluate the impedance spectroscopy parameters. Dielectric constant \({\varepsilon ^\prime }\), dielectric loss \({\varepsilon ^{\prime \prime }}\) and dielectric modulus were included and discussed in terms of dielectric polarization processes. Dielectric modulus displays the non-Debye relaxation in PtOEP: PCBM BHJ solar cells.

Photon Up-Conversion via Epitaxial Surface-Supported Metal–Organic Framework Thin Films with Enhanced Photocurrent

We report a new triplet–triplet annihilation photon up-conversion (TTA-UC) system using an epitaxial Zn-perylene surface-supported metal–organic framework (SURMOF) grown on metal oxide surface as “emitter”, and a platinum octaethylporphyrin (PtOEP) as “sensitizer” in [Co(bpy)3]2+/3+ acetonitrile solution. It has been demonstrated that the photocurrent can be significantly enhanced relative to epitaxial Zn-perylene SURMOF due to the TTA-UC mechanism. This initial result holds promising applications toward SURMOF-based solar energy conversion devices.

Metallated porphyrin-doped conjugated polymer nanoparticles for efficient photodynamic therapy of brain and colorectal tumor cells.

Assess biocompatibility, uptake and photodynamic therapy (PDT) mechanism of metallated porphyrin doped conjugated polymer nanoparticles (CPNs) in human brain and colorectal tumor cells and macrophages. CPNs were developed employing 9,9-dioctylfluorene-alt-benzothiadiazole, an amphiphilic polymer (PS-PEG-COOH), and platinum octaethylporphyrin. T98G, SW480 and RAW 264.7 cell lines were exposed to CPNs to assess uptake and intracellular localization. Additionally, a PDT protocol using CPNs was employed for thein vitro killing of cancer and macrophage cell lines. CPNs were well incorporated into glioblastoma and macrophage cells with localization in lysosomes. SW480 cells were less efficient incorporating CPNs with localization in the plasma membrane. In all cell lines PDT treatment was efficient inducing oxidative stress that triggered apoptosis.

Enhancement of triplet-sensitized upconversion in rigid polymers via singlet exciton sink approach.

To increase the practical usefulness of solid-state sensitized upconversion (UC) materials as components of solar energy harvesting systems, it is important to identify and suppress loss mechanisms, and increase the UC quantum yield (Φ UC). Here we focus on a benchmark UC system consisting of the emitter 9,10-diphenylanthracene (DPA) and the sensitizer platinum octaethylporphyrin (PtOEP) in a rigid poly(methyl methacrylate) (PMMA) matrix, and show that one of the major losses originates from Förster resonant energy transfer (FRET) from DPA back to PtOEP. Even though DPA emission lies within the PtOEP transparency window, the quantitative assessment of singlet exciton diffusion for samples with a high DPA content evidences that long-range FRET results in effective exciton trapping by PtOEP. A dramatic factor-of-6 reduction of the DPA emission quantum yield occurs even at PtOEP concentrations as low as 0.05 wt%. To alleviate this problem, we demonstrate a new concept based on the introduction of highly emissive sink sites to trap the singlet excitons produced upon annihilation prior to their quenching by the sensitizer. For DPA/PtOEP blends in PMMA, 1,6-bis-[2,5-di(dodecyloxyphenyl)ethynyl]pyrene is shown to be a useful sink, which results in 1.5-fold increase of the Φ UC. A maximum Φ UC of 2.7% was achieved, which is among the highest reported values for rigid sensitized UC polymers.

Photon upconversion in organic nanoparticles and subsequent amplification by plasmonic silver nanowires.

The development of photonic materials with high photoluminescence is always a challenge in photochemistry and photophysics. Here we present a general approach for enhancing photon upconversion through aggregation and further via surface plasmon resonance (SPR). Luminescent nanoparticles from a tetraphenylethylene derivative were fabricated, showing excellent aggregation-induced emission (AIE) behavior. By mixing with a triplet sensitizer platinum octaethylporphyrin (PtOEP), aggregation-induced photon upconversion (iPUC) could be achieved, resulting in an enhancement of the emission. Blending such iPUC nanoparticles with silver nanowires (AgNWs), the upconverted emission intensity could be significantly amplified due to the SPR of AgNWs. Thus, the concepts of aggregation-induced emission (AIE), metal enhanced fluorescence (MEF) and aggregation-induced photon upconversion (iPUC) were successfully integrated and achieved.

PVP treatment of PS/PtOEPK sensor films for improved adherence of cancer cells

Cancer cells resist some anti-cancer drugs in a hypoxic environment, which is often present in-vivo due to high proliferation rates and inadequate vasculature in dense tumour cores. Oxygen control and measurement are therefore valuable tools in culturing cancer cells in an in-vivo-like microenvironment. We report on the polyvinylpyrrolidone (PVP) treatment of polystyrene (PS)/platinum(II) octaethylporphyrin ketone (PtOEPK) fluorescent oxygen sensor films. This treatment improves cell attachment and subsequent long-term cell culture compared to native PS/PtOEPK sensor films by decreasing the water contact angle of the films to 19o, whilst sensor sensitivity to oxygen remains high (I0/I100 = 12).

Plasmon Enhancement of Triplet Exciton Diffusion Revealed by Nanoscale Imaging of Photochemical Fluorescence Upconversion

Photon upconversion based on the process of triplet–triplet annihilation in a system of organic donor and acceptor molecules has been attracting increasing attention because it can potentially lead to improved efficiency of light energy conversion devices working under sunlight irradiation. Here we aim to gain insight into the effect of localized plasmons of metal nanostructures on the individual photophysical steps involved in the upconversion mechanism. We present an optical microscopy study of the photophysical properties of plasmonic hybrid nanostructures composed of silver nanowires combined with an upconversion system consisting of platinum octaethylporphyrin donor molecules and 9,10-diphenylanthracene acceptor molecules dispersed in poly(methyl methacrylate) thin film. Using an image-splitting technique, we simultaneously record upconversion and phosphorescence microscopy images and analyze the results to decouple the individual photophysical events. In addition to moderate intensity enhancement on...

Kinetically controlled crystal growth approach to enhance triplet energy migration-based photon upconversion

Improving efficiency of triplet–triplet annihilation-based photon upconversion (TTA-UC) in crystalline media is challenging because it usually suffers from the severe aggregation of the donor (sensitizer) molecules in acceptor (emitter) crystals. We show a kinetically controlled crystal growth approach to improve donor dispersibility in acceptor crystals. As the donor–acceptor combination, a benchmark pair of platinum(II) octaethylporphyrin (PtOEP) and 9,10-diphenylanthracene (DPA) is employed. A surfactant-assisted reprecipitation technique is employed, where the concentration of the injected PtOEP–DPA solution holds the key to control dispersibility; at a higher PtOEP–DPA concentration, a rapid crystal growth results in better dispersibility of PtOEP molecules in DPA crystals. The improvement of donor dispersibility significantly enhances the TTA-UC quantum yield. Thus, the inherent function of donor-doped acceptor crystals can be maximized by controlling the crystallization kinetics.

Amplified singlet oxygen generation in metallated-porphyrin doped conjugated polymer nanoparticles

We report on the mechanism and efficiencies of singlet oxygen O2(1Δg) generation of nanoparticles (NP) of the conjugated polymer (CP) poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) doped with platinum octaethylporphyrin (PtOEP) suspended in water. A detailed study of the photophysics of these NP, using stationary and time-resolved absorption and emission techniques, indicates that O2(1Δg) is generated by the triplet excited state of F8BT and not by that of PtOEP, as previously observed for other porphyrin doped CP NP. O2(1Δg) quantum yields (ΦΔ) were measured by quantifying the characteristic phosphorescence of O2(1Δg) in the NIR region (∼1268 nm). It was found that incorporation of relatively small amounts of PtOEP to F8BT NP results in a significant increase of ΦΔ. NP containing 10% PtOEP (w/w) show a ΦΔ ∼ 0.24, which is 3 times larger than that observed for undoped F8BT NP, and larger than the reported for most water-soluble porphyrins. ΦΔ were also calculated from the oxidation rates (v0) of 3-[10-(2-carboxyethyl)anthracen-9-yl]propanoic acid (ADPA), a well-known chemical O2(1Δg) trap. Unexpectedly, this method was found to significantly overestimate the ΦΔ values due to the adsorption of ADPA on the surface of NP. The ADPA/NP adsorption process was characterized using a simple adsorption model yielding an (average) equilibrium constant of ∼8 × 103 M−1 and an (average) number of NP-binding sites of ∼14000. These results necessarily caution about the use of ADPA as a probe to evaluate ΦΔ in these NP systems. In addition, the interaction of F8BT NP with other anionic, cationic and zwitterionic dyes (dissolved in water) was studied. It was found that even at nano-molar concentrations all the dyes efficiently adsorb on the NP surface. This general and simple self-assembly strategy can be used to prepare superficially-dye-doped CP NP with potentially interesting technological applications.

Effect of gold nanoparticle on photon upconversion based on sensitized triplet–triplet annihilation in polymer films

ABSTRACTEffect of gold nanoparticle (AuNP) on photon upconversion based on sensitized triplet-triplet annihilation (PUC-TTA) were examined in the system of platinum(II) octaethylporphyrin (PtOEP) and 9,10-diphenylanthracene (DPA), when AuNPs were incorporated into polymer thin films containing PtOEP and DPA. The enhancements of the upconversion fluorescence from DPA and the phosphorescence of PtOEP were observed in the presence of AuNP. The enhancements were varied with AuNP loading and the maximum of enhancements was obtained at the AuNP loading (3.0%). The enhancements of PUC-TTA are most likely attributable to large electric fields due to localized surface plasmon resonance of AuNP.

Luminescent oxygen-sensing films with improved sensitivity based on light scattering by TiO2 particles

We investigated the effects of embedded titanium dioxide (TiO2) nanoparticles on the photocurrent and sensitivity of luminescent oxygen-sensing films based on platinum octaethylporphyrin (PtOEP), which is an indicator dye. The TiO2 nanoparticles acted as light-scattering centers in the sensing films, and the light-scattering performance was evaluated in relation to TiO2 nanoparticle diameter and crystal structure. In the presence of embedded light-scattering particles, the probabilities of PtOEP molecules encountering and being excited by light were expected to increase, resulting in improvement of the photoluminescence and sensitivity of the sensing films to oxygen gas. The diameter of the TiO2 nanoparticles was changed by laser irradiation while they were dispersed in acetone. Through the laser irradiation, the particle size of the TiO2 nanoparticles grew, and their morphology became spherical. The X-ray diffraction (XRD) analysis showed that the crystalline structure of the TiO2 nanoparticles changed in relation to its calcination temperature. The photocurrent and sensitivity of the sensing films with embedded TiO2 nanoparticles in relation to the oxygen gas concentration were measured using a green light-emitting diode (LED) as the light source and an Si photodiode as the photocurrent measuring device. Based on the results, it was confirmed that the photocurrent and sensitivity of the oxygen-sensing films were greatly improved with increases in the size and refractive index (n) of the embedded TiO2 nanoparticles. Furthermore, the improvements in the photocurrent and sensitivity of the oxygen-sensing films allowed the fabrication of a high-resolution oxygen-sensing film that can detect the oxygen distribution over large areas.

Design and Fabrication of a Ratiometric Planar Optode for Simultaneous Imaging of pH and Oxygen.

This paper presents a simple, high resolution imaging approach utilizing ratiometric planar optode for simultaneous measurement of dissolved oxygen (DO) and pH. The planar optode comprises a plastic optical film coated with oxygen indicator Platinum(II) octaethylporphyrin (PtOEP) and reference quantum dots (QDs) embedded in polystyrene (PS), pH indicator 5-Hexadecanoylamino-fluorescein (5-Fluorescein) embedded in Hydromed D4 matrix. The indicator and reference dyes are excited by utilizing an LED (Light Emitting Diode) source with a central wavelength of 405 nm, the emission respectively matches the different channels (red, green, and blue) of a 3CCD camera after eliminating the excitation source by utilizing the color filter. The result shows that there is low cross-sensitivity between the two analytes dissolved oxygen and pH, and it shows good performance in the dynamic response ranges of 0–12 mg/L and a dynamic range of pH 6−8. The optode has been tested with regard to the response times, accuracy, photostability and stability. The applied experiment for detecting pH/Oxygen of sea-water under the influence of the rain drops is demonstrated. It is shown that the planar optode measuring system provides a simple method with low cross-talk for pH/Oxygen imaging in aqueous applications.

Luminescent oxygen sensors with highly improved sensitivity based on a porous sensing film with increased oxygen accessibility and photoluminescence

In this study, we present the effects of the morphological modification of an oxygen-sensing film on improving the sensitivity of luminescent oxygen sensors. Pores were made inside the volume and on the external surface of the oxygen-sensing film consisting of platinum(II) octaethylporphyrin (PtOEP) oxygen-sensitive dye embedded in a polystyrene (PS) polymer matrix. The size of the pores with diameters from 300nm to 1μm was controlled through the phase separation of the ternary system of PS, polyethylene glycol (PEG), and chloroform. Photoluminescence (PL) intensity and oxygen accessibility of the oxygen-sensing film were considered the main factors affecting the sensitivity of the sensors. PL intensity was analyzed through the diffused reflectance and absorbance of the oxygen-sensing film. Oxygen accessibility was analyzed based on the Langmuir-Hill absorption theory by considering the sensitivity saturation behaviors of the oxygen-sensing film above the excitation light source intensity of 1000cd/m2. The optimized porous-structured oxygen-sensing film showed 61% higher sensitivity than the solid oxygen-sensing film. According to the measurement results, the sensitivity enhancement in the porous sensing film was significantly more driven by the increase in oxygen accessible sites than the increase in PL intensity. Furthermore, the sensing film with pores only on its external surface and not inside its volume showed 72% enhanced sensitivity relative to the solid sensing film. Therefore, the external surface area of the sensing film affects the sensitivity of the oxygen-sensing film significantly more than the pores inside the volume of the sensing film because the external surface acts as an oxygen diffusion barrier that limits the amount of oxygen that can access the oxygen-sensitive dye embedded in the polymer matrix.

Low‐Temperature Plasma Processing of Platinum Porphyrins for the Development of Metal Nanostructured Layers

This article establishes the bases for a vacuum and plasma supported methodology for the fabrication at mild temperatures of nanostructured platinum in the form of porous layers and nanocolumns using platinum octaethylporphyrin as precursor. In addition, the application of these materials as tunable optical filters and nano‐counterelectrodes is proved. On one hand, the transparency in the ultraviolet–visible–near infrared range can be adjusted precisely between 70% and 1% by tuning the deposition and processing conditions, obtaining a high spectral planarity. Deviations of the spectra from an ideal flat filter are below 4%, paving the way to the fabrication of neutral density filters. The transparency limit values yield a sheet resistivity of ≈1350 and 120 Ω □−1, respectively. On the other hand, the catalytic properties of the nanostructures are further demonstrated by their implementation as counterelectrodes of excitonic solar cells surpassing the performance of commercial platinum as counterelectrode in a 20% of the overall cell efficiency due to simultaneous enhancement of short‐circuit photocurrent and open‐circuit photovoltage. One of the most interesting features of the developed methodology is its straightforward application to other metal porphyrins and phthalocyanines readily sublimable under mild vacuum and temperature conditions.

Photochemical Upconversion in Silicone Core/Silica Shell Nanoparticles

We report a thorough investigation of triplet–triplet annihilation upconversion (TTA-UC) in the silicone core/silica shell hollow nanoparticles (SSNPs). The results demonstrate that Platinum(II) octaethylporphyrin (PtOEP) and 9, 10-diphenylanthracene (DPA) were successfully captured in the hollow particles. It was also observed that TTA upconversion intensity from SSNPs increases with the concentration of DPA increasing. The mobility of chromophores was improved by the liquid core of the SSNPs, leading to the increasing of TTA-UC intensity. These results shed light onto the strategies to construct TTA-UC systems in solid substrates.