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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. Flexible OLED technology is becoming increasingly mature and is ready to open new directions in antimicrobial photodynamic therapy. An international team led by Prof Ifor Samuel from University of St Andrews, UK presents a comprehensive study to show that flexible organic light-emitting diodes (OLEDs) are ideal light sources to be used in photodynamic therapy to kill bacteria. They design the OLED device structure to enable large area, high uniformity, low driving voltage, long operational lifetime, adequate shelf-life and colour tunability and address all the requirements of photodynamic therapy. Actual biological experiments show killing rates of more than 99% for S. aureus bacteria. The approach clearly demonstrates the huge potential of OLEDs for treatment of bacterial infections and future wearable healthcare devices.

Petrogal Brasil S.A., through the project “Sustainable biotechnological alternatives to increase the oil recovery factor of carbonate reservoirs” under the management of Instituto de Petróleo e Gás – ISPG and the National Agency of Petroleum, Natural Gas and Biofuels (ANP) provided financial support and grants to PJLG, PFA, ICFS, and ALBP, IDWS, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico -CNPq provided a grant to LSF, and SP had financial support and grant from the Scottish Funding Council Global Challenges Research Fund. Oil recovery is a challenge and microbial enhanced oil recovery is an option. We theorized that the use of produced water (PW) with photo-stimulation could influence both production and viscosity of Xanthan gum. This study aimed at the evaluation of the effect of photo-stimulation by λ630 ± 1 ηm LED light on the biosynthesis of Xanthan gum produced by Xanthomonas campestris IBSBF 2103 strain reusing PW of the oil industry. We assessed the effect of photo-stimulation by LED light (λ630 nm) on the biosynthesis of Xanthan gum produced by X. campestris in medium containing produced water. Different energy densities applied during the microbial growth phase were tested. The highest production was achieved when using 12 J/cm2 LED light (p

OLEDs are attractive and distinctive light sources because of they are very thin, emit over an area and can be flexible. These features also make them very interesting for medical applications as compact, lightweight sources can enable ambulatory treatment. In photodynamic therapy (PDT), light in combination with a photosensitiser leads to the generation of reactive oxygen species that can kill nearby cells. We report the development of improved OLEDs for PDT. In particular, we show their use for antimicrobial PDT i.e. for killing bacteria, parasites and fungi in vitro.

Funding: NSF grant 1545852 (OISE:PIRE-SOMBRERO)/CONACyT 251992. Organic light emitting diodes (OLEDs) are very attractive light sources because they are large area emitters and, can in principle, deposited on flexible substrates. These features make them suitable for ambulatory photodynamic therapy (PDT), in fact there are a few reports of in vitro or in vivo OLED based PDT studies for cancer or microbial inhibition but to our best knowledge, none against yeasts. Yeast infections are a significant health risk, especially in low income countries with limited medical facilities. In this work, OLED-based antimicrobial PDT (aPDT), using methylene blue (MB) as photosensitizer (PS), is studied to inactivate opportunistic yeast of four Candida strains of two species: Candida albicans and Candida tropicalis. Before aPDT experiments, fluconazole-resistance was evaluated for all strains, showing that both strains of C. tropicalis were resistant and both strains of C. albicans were sensitive to it. We found that is useful for aPDT and that 3 repetitive irradiations work better than a single dose while keeping the total fluence constant, and that this result applies whether or not the strains are resistant to fluconazole. Postprint

Funding: UK Engineering and Physical Sciences Research Council (Grant Number(s): EP/L015110/1). Antimicrobial photodynamic therapy (APDT) has been studied as a non-invasive 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, we successfully develop suitable OLEDs 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 mWcm-2) or OLED (6.5 mWcm-2) at increasing photosensitizer concentrations at a radiant exposure of 50 Jcm-2. 1,9-Dimethyl-methylene blue is the most potent photosensitizer, killing both strains at nanomolar concentrations. We also explore the effect of different intensities from the OLEDs (0.7, 1.5, and 6.5 mWcm-2) and show that effective killing of Leishmania occurs even at very low intensity. These findings demonstrate the great potential of OLEDs as a new approach for ambulatory treatment of cutaneous leishmaniasis by APDT. Publisher PDF

Electron Field Emission (FE) properties of various laser annealed thin silicon films on different substrates were investigated. HWCVD microcrystalline and PECVD amorphous silicon films were irradiated with Nd : YAG and XeCl Excimer lasers at varying energy densities. Encouraging FE results were mainly from XeCl Excimer laser processed PECVD and HWCVD films on metal backplanes. FE measurements were complemented by the study of film surface morphology. Geometric field enhancement factors from surface measurements and Fowler-Nordheim Theory (FNT) were compared. FE properties of the films were also found to be particularly influenced by the backplane material.

Artificial biomimetic substrates provide useful models for studying cell adhesion, signaling, and differentiation. This article describes biological interactions with a new type of tunable, micro-nanotextured silicon substrate, generated by irradiation of a hydrogenated amorphous silicon film with a large beam, excimer laser (248 nm). In this study, we demonstrate that BV-2 microglial cells can sense differences in laser processed silicon surface topology over the range of 30 nm to 2 μm, where they undergo marked morphogenic changes with increasing feature size. The cells adopt a more elongated shape in the presence of the modified surface structure and exhibit increased levels of actin-rich microdomains, suggesting enhanced adhesion. The excimer laser modification of hydrogenated amorphous silicon to generate micro-nanostructures realizes large area benefits as well as providing a biomaterial where the external and internal structure can be altered and tuned for various applications. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 99A: 135–140, 2011.

We present experimental and theoretical work on excimer laser microstructuring of hydrogenated amorphous silicon (a-Si∶H) films on molybdenum coated glass substrates, in the form of sharp and conical poly-Si spikes, for electron field emission applications.

The hydrogenated amorphous silicon (a-Si:H) films on molybdenum coated glass substrates were microstructured by irradiating the films using KrF excimer laser with a slope beam profile. By varying the laser processing parameters i.e., the laser pulse energy, the number of laser pulses and the laser energy distribution along the sample scan directions, the homogeneous, high density, and conical polycrystalline silicon features can be fabricated on the thin film surfaces. The electron field emission measurement results show that this kind of laser processed a- Si:H films possess good field emission characteristics with a low turn on electric field of less than 15 V/�� m and a larger saturation emission current. The diode configured field emission display devices have been demonstrated by using the laser irradiated a- Si:H films as the electron cold cathode emitters.

Thin silicon films deposited using the Hot-Wire Chemical Vapor Deposition (HWCVD) technique are studied here for the effect of XeCl excimer laser crystallization on their structural, optoelectronic, and electron field emission properties. Excimer Laser Annealing (ELA) of the silicon thin films indicated increased dark conductivity and reduced optical gap. Encouraging Field Emission (FE) results were obtained from XeCl excimer laser processed HWCVD films on Cr, V, Mo, and Ti backplanes. Geometric field enhancement factors from surface measurements and Fowler-Nordheim Theory (FNT) were compared. FE thresholds were also found to be particularly influenced by the backplane material.