Förster Resonance Energy Transfer between Fluorescent Organic Semiconductors: Poly(9,9-dioctylfluorene-alt-benzothiadiazole) and 6,13-Bis(triisopropylsilylethynyl)pentacene.

In the present study, an investigation of the electronic excitation energy transfer between two p-type fluorescent semiconductors, F8BT [poly(9,9-dioctylfluorene-alcohol-benzothiadiazole] and TIPS-P [6,13-bis(triisopropylsilylethynyl)pentacene], has been carried out in a chloroform solution using steady-state and time-domain fluorescence techniques. The spectral overlap integral between donor (F8BT) emission and acceptor (TIPS-P) absorption is 2.04 × 1015 nm4/(M cm), and the corresponding critical transfer distance is 53.12 Å. In donor decay dynamics, at the lower acceptor concentrations, the observed results deviate from the Förster theory due to the combined effect of diffusion and energy migration. However, it does not exhibit energy migration and distribution for higher acceptor concentrations, and the system follows the Förster model of resonance excitation energy transfer (FRET). The higher value of the donor-acceptor interaction strength than self-interaction (donor-donor interaction) appears to be responsible for this behavior. Further, in acceptor decay, the appearance of the rise time and its decrease with the acceptor concentration confirms FRET from F8BT to TIPS-P.

CuO Nanoparticles Decorated ZnO Nanorods Based Extended-Gate Field-Effect-Transistor (EGFET) for Enzyme-Free Glucose Sensing Application.

In this work, CuO nanoparticles (NPs) decorated zinc oxide nanorods (ZnO NRs) on fluorine-doped tin oxide (FTO) substrate has been used as a working electrode. This working electrode has been used as an extended gate for field-effect transistor. The main objective is to use the EGFET (extended gate field effect transistor) as a glucose sensor. The proposed glucose sensor has good sensitivity of 6.643 mV/mM with a wide range of linearity (1mM-8mM) which covers the glucose level of human blood ranging from 4.4 mM to 6.6 mM. This novel concept of the glucose sensing using CuO NPs decorated ZnO nanorods based EGFET may be explored for sensing other saccharides such as mannose, fructose, and sucrose. This vertically grown ZnO nanorods decorated with CuO NPs based electrode gives reliable selectivity, good repeatability, and more stability. The performance of proposed sensor is also compared with commercially available glucose sensors. The sensitivity performance of the glucose sensor also confirms the capability to detect the glucose level from human blood and serum.

Aluminium Oxide Thin-Film Based In Vitro Cell-Substrate Sensing Device for Monitoring Proliferation of Myoblast Cells.

We demonstrate cell-substrate interaction on aluminium oxide thin-film in metal-insulator-metal structure followed by the change in dielectric characteristics of Al2O3 as a function of progression of cellular growth. The theoretical calculation of the fabricated biosensor reveals that the changes in the intrinsic elemental parameters are mainly attributed to the cell-induced behavioural changes.

Functional Behavior of the Primary Cortical Neuronal Cells on the Large Surface of TiO2 and SnO2 Based Biosensing Device.

In this study, we report the fabrication of poly-L-lysine (PLL) coated large surface TiO2 and SnO2 based biosensing devices to analyze the influence of the functional behaviour of primary cortical neuronal cells. Through frequency-dependent impedance study, we observed an increase in the impedance values initially most likely due to cell adhesion, proliferation and differentiation processes leading to an increase in both the single-cell mass as well as overall cellular mass; however, it got decreased eventually with the progression of various other cellular functions including neural activity, synapse formation and neuron-neuron communication. Typically, formation and regulation of the neuronal junction i.e., synapses noticeably affected the functional behaviour of the fabricated biosensing device by increasing the neuronal communication and thereby improving the flow of current by altering the thin film resistance and capacitance. Further, the neuro-electrical phenomenon is validated by fitting the experimental impedance data to an equivalent electrical circuit model. A significant shift in the Nyquist plot was also observed visually, which indicates that this alternation is primarily due to change in characteristic behaviour of the fabricated biosensing device. Hence, we anticipate that the fabricated PLL coated large surface TiO2 and SnO2 based biosensing device can serve as a promising tool to monitor the influence of the functional behaviour of neuronal cells.

Author Correction: Au nanoparticles modified CuO nanowire electrode based non-enzymatic glucose detection with improved linearity.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Synergistic effect of CdSe quantum dots (QDs) and PC61BM on ambient-air processed ZnO QDs/PCDTBT: PC61BM:CdSe QDs/MoO3 based ternary organic solar cells.

This paper reports the synergistic effect of colloidal CdSe quantum dots (QDs) and PC61BM on the performance of ITO/ZnO QDs/PCDTBT:PC61BM:CdSe QDs/MoO3/Ag based ternary organic solar cells (OSCs). The MoO3 and ZnO QDs (∼2.87 nm) layers work as the transparent hole transport layer (HTL) and electron transport layer (ETL), respectively. The CdSe QDs (∼4.58 nm) are blended with PC61BM:PCDTBT binary solution to improve the optical properties and charge transportation. Significant photoluminescence (PL) quenching is observed when part of the PC61BM is replaced by CdSe QDs with equivalent weight in the PCDTBT. The proposed ternary OSC gives an open-circuit voltage of 854 mV, a short circuit current density of 14 mA cm-2, fill factor of 42% and power conversion efficiency (PCE) of 5.02%. The PCE of the ternary OSC is increased by more than 38% compared to the binary OSC. This significant improvement in the performance parameters is attributed to the enhanced absorption and higher transportation of photo-generated charge carriers, as well as the increased charge dissociation due to the synergistic effect of CdSe QDs and PC61BM. The external quantum efficiency is also enhanced significantly in the ternary OSC due to the better conversion of solar energy into electrical energy.

Au nanoparticles modified CuO nanowireelectrode based non-enzymatic glucose detection with improved linearity.

This paper explores gold nanoparticle (GNP) modified copper oxide nanowires(CuO NWs)based electrode grown on copper foil for non-enzymatic glucose detection in a wide linear ranging up to 31.06 mM, and 44.36 mM at 0.5 M NaOH and 1 M NaOH concentrations. The proposed electrode can be used to detect a very low glucose concentration of 0.3 µM with a high linearity range of 44.36mM and sensitivity of 1591.44 µA mM-1 cm-2. The electrode is fabricated by first synthesizing Cu (OH)2 NWs on a copper foil by chemical etching method and then heat treatment is performed to convert Cu (OH)2 NWs into CuO NWs. The GNPs are deposited on CuO NWs to enhance the effective surface-to-volume ratio of the electrode with improved catalytic activity. The surface morphology has been investigated by XRD, XPS, FE-SEM and HR-TEM analysis. The proposed sensor is expected to detect low-level of glucose in urine, and saliva. At the same time, it can also be used to measure extremely high sugar levels (i.e. hyperglycemia) of ~ 806.5454 mg/dl. The proposed sensor is also capable of detecting glucose after multiple bending of the GNP modified CuO NWs electrode. The proposed device is also used to detect the blood sugar level in human being and it is found that this sensor's result is highly accurate and reliable.

Excited-State Dynamics of Quinine Sulfate and Its Di-Cation Doped in Polyvinyl Alcohol Thin Films Near Silver Nanostructure Islands.

The present study demonstrates the near-field effect of silver nanostructure island films (SNIFs) on the photophysics and exited-state dynamics of quinine sulphate (QS) and its di-cation (QSD), doped in polyvinyl alcohol (PVA) films. The results indicate a nearly 3.8-fold enhancement in absorption and 4000-fold enhancement in fluorescence in SNIF-coated QS-doped PVA films, whereas only twofold enhancement in absorption and sevenfold enhancement in fluorescence intensity are found in SNIF-coated QSD-doped PVA films. However, an increase in photostability and a decrease in decay time have been observed in both the SNIF-coated films as compared to their uncoated forms. Further, a decrease in the magnitude of the edge excitation red shift in emission spectra along with a red shift in the La band and a rise in the intensity of the Lb band of excitation is observed in SNIF-coated QSD films because of strong coupling of the Lb band with the surface plasmons of silver nanoparticles. Moreover, X-ray photoelectron spectroscopic measurement of silver nanoparticle-coated QS-PVA films shows no change in 3d3/2 and 3d5/2 transitions of silver, whereas the decrease in energy in these silver transitions in the QSD-PVA system is observed as compared to silver nanoparticle-coated PVA films. These results indicate the formation of a field-governed radiating plasmon and plasmon-coupled unified fluorophore system, respectively. This affects the photophysics of both of the molecules by plasmonic coupling of the Frank-Condon state, solvent relaxation state, and charge-transfer state by different orders of magnitude.

Fabrication and characterization of a ZnO quantum dots-based metal-semiconductor-metal sensor for hydrogen gas.

This paper reports an interdigitated metal-semiconductor-metal (MSM) based hydrogen gas (H2) sensor using colloidal zinc oxide (ZnO) quantum dots (QDs) as the sensing material. The active layer is obtained by spin coating of as-synthesized colloidal ZnO QDs on a SiO2/Si substrate in which the SiO2 layer is grown by oxidation of the Si substrate. The surface morphology of a ZnO QDs -based active film is measured using scanning electron microscopy (SEM) and atomic force microscopy (AFM) support for enhanced gas response. The change in current is measured for different concentrations of H2 gas at 175 °C in an ambient air atmosphere. Reasonably good gas responses of ∼41% for 1% H2 gas and 83.2% for 4% H2 gas have been obtained in ambient air condition. A high selectivity of the proposed sensor with respect to ammonia, sulfur dioxide and organic vapours such as acetone, methanol, chlorobenzene, and chloroform has also been achieved due to nanostructure ZnO films.

Superficial fabrication of gold nanoparticles modified CuO nanowires electrode for non-enzymatic glucose detection.

This paper describes a low-cost facile method to construct gold (Au) nanoparticles (NPs) modified copper oxide (CuO) nanowires (NWs) electrode on copper foil for the detection of glucose. Copper foil has been converted to aligned CuO NWs arrays by sequential formation of Cu(OH)2 followed by heat treatment induced phase transformation to CuO. Au NPs are deposited on CuO NWs via simple reductive solution chemistry to impart high surface to volume ratio and enhanced catalytic activity of the resulting electrode. Structure, microstructure and morphology of Cu, Cu(OH)2 NWs, CuO NWs, and Au NPs modified CuO NWs are investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The homogeneous distribution of Au NPs (average diameter ∼12 nm) on CuO NWs (average diameter 100 nm and aspect ratio ∼20) is confirmed by high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) and elemental mapping. This CuO based glucose detection method gives the highest sensitivity along with the maximum linearity range. This non-enzymatic glucose sensor based on Au modified CuO NWs electrode gives broad linearity range from 0.5 µM to 5.9 mM. The sensor exhibits sensitivity of 4398.8 µA mM-1 cm-2, lower detection limit of 0.5 µM, and very fast response time of ∼5 s. Properties of the proposed glucose sensor are also investigated in human blood and it is found that the sensor is highly accurate and reliable. In addition, higher sensitivity and lower detection limit confirm that this device is suitable for invasive detection in saliva and urine.