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.

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.

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Here we demonstrate the two-tier manipulation of holographic information using frequency-selective metasurfaces. Our results show that these devices can diffract light efficiently at designed frequency and environmental conditions. By changing the frequency and refractive index of the surrounding environment, the metasurfaces produce two different holographic images. We anticipate that these environmental dependent, frequency-selective metasurfaces will have practical applications in holographic encryption and sensing.

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.