Bacterial infection and the growth of antibiotic resistance is a serious problem that leads to patient suffering, death and increased costs of healthcare. To address this problem, we propose using flexible organic light-emitting diodes (OLEDs) as light sources for photodynamic therapy (PDT) to kill bacteria. PDT involves the use of light and a photosensitizer to generate reactive oxygen species that kill neighbouring cells. We have developed flexible top-emitting OLEDs with the ability to tune the emission peak from 669 to 737 nm to match the photosensitizer, together with high irradiance, low driving voltage, long operational lifetime and adequate shelf-life. These features enable OLEDs to be the ideal candidate for ambulatory PDT light sources. A detailed study of OLED-PDT for killing Staphylococcus aureus was performed. The results show that our OLEDs in combination with the photosensitizer methylene blue, can kill more than 99% of bacteria. This indicates a huge potential for using OLEDs to treat bacterial infections.
Antimicrobial photodynamic therapy (APDT) is a promising approach to fight the growing problem of antimicrobial resistance that threatens health care, food security and agriculture. Suitable light sources include lasers, LEDs, OLEDs and lamps.
We report an organic emitter containing a β-triketone electron acceptor core and phenoxazine as the electron donors (TPXZBM) for solution-processed organic light-emitting diodes (OLEDs). The resulting molecule is very unusual because it shows both thermally activated delayed fluorescence and intramolecular proton transfer. We compare its performance with the previously reported diketone analogue PXZPDO. Solutionprocessed OLEDs of PXZPDO and TPXZBM show maximum external quantum efficiencies of 20.1 and 12.7%, respectively. The results obtained for the solution-processed PXZPDO-based device are as good as the previously reported evaporated device. At a very high luminance of 10,000 cd m −2 , the efficiencies of the OLEDs were 10.6% for PXZPDO and 4.7% for TPXZBM, demonstrating a relatively low efficiency roll-off for TADF materials. The low efficiency roll-off was rationalized on the basis of the short delayed lifetimes of 1.35 μs for PXZPDO and 1.44 μs for TPXZBM. Our results suggest that intramolecular proton transfer may be useful for the design of OLED materials with a low efficiency roll-off.
Antimicrobial photodynamic therapy (APDT) has been studied as a noninvasive therapy for treating cutaneous leishmaniasis to overcome challenges with current treatment, such as toxicity, resistance, and need for in‐patient hospital treatment. Organic light‐emitting diodes (OLEDs) have emerged as an attractive technology that can provide wearable light‐emitting materials that are conformable to human skin. This makes OLEDs ideal candidates for APDT by light‐bandages for ambulatory care. In this work, suitable OLEDs are successfully developed to match the absorbance of three photosensitizers: methylene blue, new methylene blue, and 1,9‐dimethyl‐methylene blue to inactivate two Leishmania species in vitro: Leishmania major and Leishmania amazonensis. Parasites are treated either by LED (20 mW cm−2) or OLED (6.5 mW cm−2) at increasing photosensitizer concentrations at a radiant exposure of 50 J cm−2. 1,9‐Dimethyl‐methylene blue is the most potent photosensitizer, killing both strains at nanomolar concentrations. The effect of different intensities from the OLEDs (0.7, 1.5, and 6.5 mW cm−2) are also explored and it is shown that effective killing of Leishmania occurs even at a very low intensity. These findings demonstrate the great potential of OLEDs as a new approach for ambulatory treatment of cutaneous leishmaniasis by APDT.
enzyme-linked immunoabsorbent assay (ELISA) and quantitative polymerase chain reaction (qPCR) is often expensive, cumbersome, and time-consuming. This means it is not available in primary care. In addition, the imbalance of healthcare resources between developed and developing countries [2] , limits the access of people living in developing countries to such advanced diagnostics. [3] Therefore, it is desirable to employ technologies that are cheap to produce and deploy, portable with rapid feedback of results while maintaining the device sensitivity and robustness uncompromised.A point-of-care (POC) diagnostic test is a medical laboratory diagnostic test intended to be carried out in the direct vicinity of the patients, with the result obtained in a short time (30 to 60 min). In addition, these tests should be designed to be carried out by personnel who are not trained in a medical laboratory, such as medical assistants or patients themselves. One of the most common examples of POC devices is the lateral flow device (LFD) for pregnancy test, which only needs a few drops of a urine sample to indicate pregnancy in a very short time. In the pregnancy test LFD, gold nanoparticles are used as the indicator to show the results with visual inspection of line color. [4] It gives a qualitative result with relatively low-cost and simple readout method. To further improve the system for more sensitive and quantitative measurement, optical systems with fluorescent detection have been developed. [5] In fluorescence sensing, a light source excites the fluorescence of a dyelabelled analytes. Fluorescence sensing has advantages of lowbackground, fast-response, and is widely used in diagnostics. Therefore, the basic components to perform fluorescence sensing at least involves a light source and a detector. However, most fluorescence sensing systems use bulky and expensive equipment such as lasers, filtered lamp, photomultiplier, microscope, and spectrometers to enhance the sensitivity of system, which are difficult to be integrated into a compact device for POC purpose. Light-emitting diodes (LEDs) are being explored as potential compact light sources for POC fluorescence. [6][7][8] Organic light-emitting diodes (OLEDs) are made from thin layers of organic semiconductors. They are promising candidates for POC fluorescence sensing because they are compact, lightweight, thin and can easily be integrated with other sensing components. [9,10] OLEDs have several advantages compared to their inorganic counterparts. They are simple to make by thermal evaporation at moderate temperature, and Conventional fluorescence sensing equipment for disease detection is expensive and bulky, restricting access of patients to accurate diagnosis. Organic light-emitting diodes (OLEDs) have the potential to enable compact fluorescence sensing compatible with point-of-care (POC) testing. However, the limited brightness and broad emission spectra of OLEDs can be a challenge for achieving good sensitivity. Here, co-host microcavity OLEDs with narrowed spec...
Immunodiagnostics have been widely used in the detection of disease biomarkers. The conventional immunological tests in central laboratories require expensive equipment and, for non-specialists, the tests are technically demanding and time-consuming, which has prevented their use by the public. Thus, point-of-care tests (POCT), such as lateral flow immunoassays, are being, or have been, developed as more convenient and low-cost methods for immunodiagnostics. However, the sensitivity of such tests is often a concern. Here, a fluorescence-linked immunosorbent assay (FLISA) using organic light-emitting diodes (OLEDs) as excitation light sources was investigated as a way forward for the development of compact and sensitive POCTs. Phycoerythrin (PE) was selected as the fluorescent dye, and OLEDs were designed with different emission spectra. The leakage light of different OLEDs for exciting PE was then investigated to reduce the background noise and improve the sensitivity of the system. Finally, as proof-of-principle that OLED-based technology can be successfully further developed for POCT, antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in human serum was detected by OLED−FLISA.
Herein, we used a photosensitizing agent and red organic light-emitting diodes (OLEDs) against two strains of Leishmania amazonensis amastigotes, including a drug-resistant line. OLEDs are promising wearable light sources for photodynamic therapy of cutaneous leishmaniasis.
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