Phosphorimetric Characterization of Solution-Processed Polymeric Oxygen Barriers for the Encapsulation of Organic Electronics

We describe the use of a modified Stern-Volmer photokinetic model for the determination of the oxygen-permeation coefficient (PO2) of materials that can be used as barriers against oxygen permeation in organic electronic applications. The model is applied on photophysical data collected based on the use of the optical technique of phosphorimetry for the oxygen-sensing organometallic complex (2,3,7,8,12,13,17,18-octaethylporphyrinato)platinum(II) (PtOEP). PtOEP is used as a phosphorescent probe encapsulated by a set of model solution-processed transparent oxygen-barrier layers made by the polymers of poly(norbornene), poly(methyl methacrylate), poly(styrene), and Zeonex. For each barrier system the oxygen-induced quenching of the PtOEP phosphorescence is monitored with the study of the time-integrated and time-resolved PtOEP phosphorescence intensity, as a function of the partial pressure of oxygen. The advantage of utilizing the presented photokinetic model is based on the consideration of the fractional accessibility of the excited triplet states to the permeant oxygen. The extracted values of PO2 are in excellent agreement with the previous literature, confirming the validity of the modified Stern-Volmer model employed in the analysis of the photophysical data. The results suggest that phosphorimetric characterization is a simple and inexpensive methodology for the fast screening of next-generation barrier materials for organic electronic devices. The high sensitivity of the phosphorimetric technique is shown in the successful characterization of a commonly used glass/epoxy barrier system for which PO2 = 39 × 10-16 cm3 (STP) ·cm·cm -2·s-1·Pa-1 is found. The findings of the phosphorimetric characterization are in qualitative agreement with a preliminary shelf lifetime stability test of organic solar cell devices that were encapsulated with some of the barrier materials of the study. © 2014 American Chemical Society

Phosphorimetric Characterization of Solution-Processed Polymeric Oxygen Barriers for the Encapsulation of Organic Electronics

We describe the use of a modified Stern-Volmer photokinetic model for the determination of the oxygen-permeation coefficient (PO2) of materials that can be used as barriers against oxygen permeation in organic electronic applications. The model is applied on photophysical data collected based on the use of the optical technique of phosphorimetry for the oxygen-sensing organometallic complex (2,3,7,8,12,13,17,18-octaethylporphyrinato)platinum(II) (PtOEP). PtOEP is used as a phosphorescent probe encapsulated by a set of model solution-processed transparent oxygen-barrier layers made by the polymers of poly(norbornene), poly(methyl methacrylate), poly(styrene), and Zeonex. For each barrier system the oxygen-induced quenching of the PtOEP phosphorescence is monitored with the study of the time-integrated and time-resolved PtOEP phosphorescence intensity, as a function of the partial pressure of oxygen. The advantage of utilizing the presented photokinetic model is based on the consideration of the fractional accessibility of the excited triplet states to the permeant oxygen. The extracted values of PO2 are in excellent agreement with the previous literature, confirming the validity of the modified Stern-Volmer model employed in the analysis of the photophysical data. The results suggest that phosphorimetric characterization is a simple and inexpensive methodology for the fast screening of next-generation barrier materials for organic electronic devices. The high sensitivity of the phosphorimetric technique is shown in the successful characterization of a commonly used glass/epoxy barrier system for which PO2 = 39 × 10-16 cm3 (STP) ·cm·cm -2·s-1·Pa-1 is found. The findings of the phosphorimetric characterization are in qualitative agreement with a preliminary shelf lifetime stability test of organic solar cell devices that were encapsulated with some of the barrier materials of the study. © 2014 American Chemical Society

Fullerene-free organic solar cells with an efficiency of 3.7% based on a low-cost geometrically planar perylene diimide monomer

The aggregate-induced limitation for high power-conversion efficiencies (PCEs) of perylene-diimide (PDI): polymer solar cells can be circumvented when two simple rules are respected; the aggregate size of PDI remains short enough and the omnipresent PDI aggregates are electronically interconnected. Following these guidelines, a PCE of 3.7% is delivered by using the solution-processable, planar PDI monomer of N,N’-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxylic diimide as the electron acceptor mixed with the low-energy gap polymeric donor poly[(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b;4,5-b’]dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene))-2,6-diyl] (PBDTTT-CT). The PBDTTT-CT:PDI composite absorbs strongly the light in the region of 400 nm–800 nm and after adding a small amount of 1,8-diiodooctane (DIO) efficient photocurrent generation is achieved. Space-charge limited dark current and transient photovoltage measurements suggest that the use of the DIO component optimizes the electron/hole carrier mobility ratio, suppresses the non-geminate recombination losses and improves the charge extraction efficiency

Phosphorimetric Characterization of Solution-Processed Polymeric Oxygen Barriers for the Encapsulation of Organic Electronics

We describe the use of a modified Stern–Volmer photokinetic model for the determination of the oxygen-permeation coefficient (<i>P</i>^O₂) of materials that can be used as barriers against oxygen permeation in organic electronic applications. The model is applied on photophysical data collected based on the use of the optical technique of phosphorimetry for the oxygen-sensing organometallic complex (2,3,7,8,12,13,17,18-octaethylporphyrinato)­platinum­(II) (PtOEP). PtOEP is used as a phosphorescent probe encapsulated by a set of model solution-processed transparent oxygen-barrier layers made by the polymers of poly­(norbornene), poly­(methyl methacrylate), poly­(styrene), and Zeonex. For each barrier system the oxygen-induced quenching of the PtOEP phosphorescence is monitored with the study of the time-integrated and time-resolved PtOEP phosphorescence intensity, as a function of the partial pressure of oxygen. The advantage of utilizing the presented photokinetic model is based on the consideration of the fractional accessibility of the excited triplet states to the permeant oxygen. The extracted values of <i>P</i>^O₂ are in excellent agreement with the previous literature, confirming the validity of the modified Stern–Volmer model employed in the analysis of the photophysical data. The results suggest that phosphorimetric characterization is a simple and inexpensive methodology for the fast screening of next-generation barrier materials for organic electronic devices. The high sensitivity of the phosphorimetric technique is shown in the successful characterization of a commonly used glass/epoxy barrier system for which <i>P</i>^O₂ = 39 × 10^–16 cm³ (STP) ·cm·cm^–2·s^–1·Pa^–1 is found. The findings of the phosphorimetric characterization are in qualitative agreement with a preliminary shelf lifetime stability test of organic solar cell devices that were encapsulated with some of the barrier materials of the study

Structural color tuning in 1D photonic crystals with electric field and magnetic field

A tuning of the light transmission properties of 1D photonic structures employing an external stimulus is very attracting and opens the way to the fabrication of optical switches for colour manipulation in sensing, lighting, and display technology. We present the electric field-induced tuning of the light transmission in a photonic crystal device, made by alternating layers of silver nanoparticles and titanium dioxide nanoparticles. We show a shift of around 10 nm for an applied voltage of 10 V. We ascribe the shift to an accumulation of charges at the silver/TiO2 interface due to electric field, resulting in an increase of the number of charges contributing to the plasma frequency in silver, giving rise to a blue shift of the silver plasmon band, with concomitant blue shift of the photonic band gap. The employment of a relatively low applied voltage gives the possibility to build a compact and low-cost device(1). We also propose the fabrication of 1D photonic crystal and microcavities employing a magneto-optical material as TGG (Tb3Ga5O12). With these structures we can observe a shift of 22 nm with a magnetic field of 5 T, at low temperature (8 K). The option to tune the colour of a photonic crystal with magnetic field is interesting because of the possibility to realize contactless optical switches(2). We also discuss the possibility to achieve the tuning of the photonic band gap with UV light in photonic crystals made with indium tin oxide (ITO)

PET Imaging of the Neurotensin Targeting Peptide NOTA-NT-20.3 Using Cobalt-55, Copper-64 and Gallium-68

Introduction: Neurotensin receptor 1 (NTSR1) is an emerging target for imaging and therapy of many types of cancer. Nuclear imaging of NTSR1 allows for noninvasive assessment of the receptor levels of NTSR1 on the primary tumor, as well as potential metastases. This work focuses on a the neurotensin peptide analogue NT-20.3 conjugated to the chelator NOTA for radiolabeling for use in noninvasive positron emission tomography (PET). NOTA-NT-20.3 was radiolabeled with gallium-68, copper-64, and cobalt-55 to determine the effect that modification of the radiometal has on imaging and potential therapeutic properties of NOTA-NT-20.3. Methods: In vitro assays investigating cell uptake and subcellular localization of the radiolabeled peptides were performed using human colorectal adenocarcinoma HT29 cells. In vivo PET/CT imaging was used to determine the distribution and clearance of the peptide in mice bearing NTSR1 expressing HT29 tumors. Results: Cell uptake studies showed that the highest uptake was obtained with [55Co] Co-NOTA-NT-20.3 (18.70 ± 1.30%ID/mg), followed by [64Cu] Cu-NOTA-NT-20.3 (15.46 ± 0.91%ID/mg), and lastly [68Ga] Ga-NOTA-NT-20.3 (10.94 ± 0.46%ID/mg) (p 55Co] Co-NOTA-NT-20.3 (20.28 ± 3.04) outperformed [64Cu] Cu-NOTA-NT-20.3 (6.52 ± 1.97). In conclusion, our studies show that enhanced cell uptake and increasing tumor to blood ratios over time displayed the superiority of [55Co] Co-NOTA-NT-20.3 over [68Ga] Ga-NOTA-NT-20.3 and [64Cu] Cu-NOTA-NT-20.3 for the targeting of NTSR1

Antibody fragment and affibody immunoPET imaging agents: radiolabelling strategies and applications

Antibodies have long been recognised as potent vectors for carrying diagnostic medical radionuclides, contrast agents and optical probes to diseased tissue for imaging. The area of ImmunoPET combines the use of positron emission tomography (PET) imaging with antibodies to improve the diagnosis, staging and monitoring of diseases. Recent developments in antibody engineering and PET radiochemistry have led to a new wave of experimental ImmunoPET imaging agents that are based on a range of antibody fragments and affibodies. In contrast to full antibodies, engineered affibody proteins and antibody fragments such as minibodies, diabodies, single‐chain variable region fragments (scFvs), and nanobodies are much smaller but retain the essential specificities and affinities of full antibodies in addition to more desirable pharmacokinetics for imaging. Herein, recent key developments in the PET radiolabelling strategies of antibody fragments and related affibody molecules are highlighted, along with the main PET imaging applications of overexpressed antigen‐associated tumours and immune cells

A High Separation Factor for ¹⁶⁵Er from Ho for Targeted Radionuclide Therapy

Background: Radionuclides emitting Auger electrons (AEs) with low (0.02–50 keV) energy, short (0.0007–40 µm) range, and high (1–10 keV/µm) linear energy transfer may have an important role in the targeted radionuclide therapy of metastatic and disseminated disease. Erbium-165 is a pure AE-emitting radionuclide that is chemically matched to clinical therapeutic radionuclide 177Lu, making it a useful tool for fundamental studies on the biological effects of AEs. This work develops new biomedical cyclotron irradiation and radiochemical isolation methods to produce 165Er suitable for targeted radionuclide therapeutic studies and characterizes a new such agent targeting prostate-specific membrane antigen. Methods: Biomedical cyclotrons proton-irradiated spot-welded Ho(m) targets to produce 165Er, which was isolated via cation exchange chromatography (AG 50W-X8, 200–400 mesh, 20 mL) using alpha-hydroxyisobutyrate (70 mM, pH 4.7) followed by LN2 (20–50 µm, 1.3 mL) and bDGA (50–100 µm, 0.2 mL) extraction chromatography. The purified 165Er was radiolabeled with standard radiometal chelators and used to produce and characterize a new AE-emitting radiopharmaceutical, [165Er]PSMA-617. Results: Irradiation of 80–180 mg natHo targets with 40 µA of 11–12.5 MeV protons produced 165Er at 20–30 MBq·µA−1·h−1. The 4.9 ± 0.7 h radiochemical isolation yielded 165Er in 0.01 M HCl (400 µL) with decay-corrected (DC) yield of 64 ± 2% and a Ho/165Er separation factor of (2.8 ± 1.1) · 105. Radiolabeling experiments synthesized [165Er]PSMA-617 at DC molar activities of 37–130 GBq·µmol−1. Conclusions: A 2 h biomedical cyclotron irradiation and 5 h radiochemical separation produced GBq-scale 165Er suitable for producing radiopharmaceuticals at molar activities satisfactory for investigations of targeted radionuclide therapeutics. This will enable fundamental radiation biology experiments of pure AE-emitting therapeutic radiopharmaceuticals such as [165Er]PSMA-617, which will be used to understand the impact of AEs in PSMA-targeted radionuclide therapy of prostate cancer