Enhanced Capacitive Humidity Sensing Performance at Room Temperature via Hydrogen Bonding of Cyanopyridone-Based Oligothiophene Donor

Cyanopyridone-based oligothiophene donors with both hydrophobic and hydrophilic characters have been evaluated as active layers within simple capacitive devices for humidity sensing at room temperature. Surface studies using atomic force microscopy revealed a self-assembled nanofibrous network with a thin needle-like structure for the terminal hydroxy example (CP6), devoid in the methyl example (CP1). The sensing performance of each sensor was investigated over a broad range of relative humidity levels as a function of capacitance at room temperature. The sensor CP6 demonstrated favourable features such as high sensitivity (12.2 pF/%RH), quick response/recovery (13 s/20.7 s), wide working range of relative humidity (10%–95% RH), low hysteresis (0.57%), outstanding recyclability, and excellent long-term stability. From the results obtained, hydrophilicity and hydrogen bonding appear to play a vital role in enhancing humidity sensing performance, leading to possible new design directions for simple organic semiconductor-based sensors.</jats:p

The p21-Dependent Radiosensitization of Human Breast Cancer Cells by MLN4924, an Investigational Inhibitor of NEDD8 Activating Enzyme

Radiotherapy is a treatment choice for local control of breast cancer. However, intrinsic radioresistance of cancer cells limits therapeutic efficacy. We have recently validated that SCF (SKP1, Cullins, and F-box protein) E3 ubiquitin ligase is an attractive radiosensitizing target. Here we tested our hypothesis that MLN4924, a newly discovered investigational small molecule inhibitor of NAE (NEDD8 Activating Enzyme) that inactivates SCF E3 ligase, could act as a novel radiosensitizing agent in breast cancer cells. Indeed, we found that MLN4924 effectively inhibited cullin neddylation, and sensitized breast cancer cells to radiation with a sensitivity enhancement ratio (SER) of 1.75 for SK-BR-3 cells and 1.32 for MCF7 cells, respectively. Mechanistically, MLN4924 significantly enhanced radiation-induced G2/M arrest in SK-BR-3 cells, but not in MCF7 cells at early time point, and enhanced radiation-induced apoptosis in both lines at later time point. However, blockage of apoptosis by Z-VAD failed to abrogate MLN4924 radiosensitization, suggesting that apoptosis was not causally related. We further showed that MLN4924 failed to enhance radiation-induced DNA damage response, but did cause minor delay in DNA damage repair. Among a number of tested SCF E3 substrates known to regulate growth arrest, apoptosis and DNA damage response, p21 was the only one showing an enhanced accumulation in MLN4924-radiation combination group, as compared to the single treatment groups. Importantly, p21 knockdown via siRNA partialy inhibited MLN4924-induced G2/M arrest and radiosensitization, indicating a causal role played by p21. Our study suggested that MLN4924 could be further developed as a novel class of radiosensitizer for the treatment of breast cancer

Capacitive humidity sensing performance of naphthalene diimide derivatives at ambient temperature

We report for the first-time the development of capacitive type humidity sensors employing naphthalene diimide derivatives (NDI) as sensing layer. Three different naphthalene diimide derivatives bearing imide side chains of different hydrophilicity were designed, synthesised and characterised. X-ray diffraction and thermogravimetric analyses gave useful information about structural and thermal behaviour of the newly developed materials, indicating their crystallinity and stability. Atomic force microscopy analysis revealed a variety of morphologies in thin films as a result of the structural properties of the NDIs. Devices bearing NDI layers were fabricated on ceramic substrates with gold interdigitated electrodes spaced 200 µm apart. Humidity sensing performance, as a change in capacitance, was studied upon exposure to a wide range of relative humidity levels (0–95%) at ambient temperature. Importantly, an increase in the capacitance of the sensors was recorded with an increase in relative humidity. The developed sensors exhibited high sensitivity, good long-term stability, excellent reproducibility, and low hysteresis. The sensor performance was also tested against different operating frequencies (250 Hz–2 kHz) to improve linearity, illustrating directions for optimised performance. These results confirm that sensors based on NDIs possess better sensing performance to other types of reported capacitive humidity sensors

Enhancement in room temperature ammonia sensing properties of naphthalene diimides through core expansion

An amperometric sensor whose active layer is derived from a tetra core-substituted organic semiconductor, naphthalene diimide (NDI-CN4), has been evaluated for ammonia sensing at room temperature against the NDI devoid of core-substitution effects.</jats:p

Naphthalene diimide-based electron transport materials for perovskite solar cells

The development of perovskite solar cells (PSCs) as an efficient and cost-effective alternative to traditional approaches to solar energy transduction has received much recent attention, and there has been considerable progress made with reported power conversion efficiencies now surpassing 25%. This development is encouraging and is a result of intensive research on device design, factors affecting long-term stability of PSCs, and systematic material development in which electron transport layer (ETL) materials play a crucial role to afford high-performance PSC devices. ETL materials, including (6-(1,10-phenanthrolin-3-yl)naphthalen-2-yl)diphenylphosphine oxide (Phen-NaDPO), and n-type materials based on the naphthalene diimide (NDI) structure, appear to be amongst the most promising materials to date. This article provides an up-to-date review on organic n-type ETL materials, both polymeric and small molecules, based on NDI format, detailing reports of structures with key relevant parameters, such as the efficiency and stability of PSCs. The review is written from a perspective of organic chemistry and we believe this will provide fundamental advice on the future design of new ETL materials based on NDIs that will afford more efficient and stable PSCs

Functionalization of spiro[fluorene-9,9′-xanthene] with diketopyrrolopyrrole to generate a promising, three-dimensional non-fullerene acceptor

A spiro[fluorene-9,9′-xanthene], often described as a "low-cost spiro,"has been functionalized with terminal diketopyrrolopyrrole units to generate a promising, three-dimensional non-fullerene acceptor. The new acceptor, coded as SFX1, was readily synthesized using the Suzuki cross-coupling reaction and was sufficiently soluble in a variety of commonly used, film-processing solvents such as chlorobenzene and o-dichlorobenzene. SFX1 displayed promising optoelectronic properties and the HOMO/LUMO energy levels complementary to the commercially available and commonly used donor polymers P3HT and PTB7. The joining of two high-potential building blocks-the spiro[fluorene-9,9′-xanthene] and diketopyrrolopyrrole-demonstrates a new strategy where the device performance [D : A 1 : 1.2 = 9.42% (D = PTB7)] validates its use as a potential, three-dimensional non-fullerene acceptor