Replica of Bionic Nepenthes Peristome-like and Anti-Fouling Structures for Self-Driving Water and Raman-Enhancing Detection.

The flexible, anti-fouling, and bionic surface-enhanced Raman scattering (SERS) biochip, which has a Nepenthes peristome-like structure, was fabricated by photolithography, replicated technology, and thermal evaporation. The pattern of the bionic Nepenthes peristome-like structure was fabricated by two layers of photolithography with SU-8 photoresist. The bionic structure was then replicated by polydimethylsiloxane (PDMS) and grafting the zwitterion polymers (2-methacryloyloxyethyl phosphorylcholine, MPC) by atmospheric plasma polymerization (PDMS-PMPC). The phospholipid monomer of MPC immobilization plays an important role; it can not only improve hydrophilicity, anti-fouling and anti-bacterial properties, and biocompatibility, but it also allows for self-driving and unidirectional water delivery. Ag nanofilms (5 nm) were deposited on a PDMS (PDMS-Ag) substrate by thermal evaporation for SERS detection. Characterizations of the bionic SERS chips were measured by a scanning electron microscope (SEM), optical microscope (OM), X-ray photoelectron spectrometer (XPS), Fourier-transform infrared spectroscopy (FTIR), and contact angle (CA) testing. The results show that the superior anti-fouling capability of proteins and bacteria (E. coli) was found on the PDMS-PMPC substrate. Furthermore, the one-way liquid transfer capability of the bionic SERS chip was successfully demonstrated, which provides for the ability to separate samples during the flow channel, and which was detected by Raman spectroscopy. The SERS intensity (adenine, 10-4 M) of PDMS-Ag with a bionic structure is ~4 times higher than PDMS-Ag without a bionic structure, due to the multi-reflection of the 3D bionic structure. The high-sensitivity bionic SERS substrate, with its self-driving water capability, has potential for biomolecule separation and detection.

Selective oxygen-plasma-etching technique for the formation of ZnO-FTO heterostructure nanotubes and their rectified photocatalytic properties.

A novel ZnO-FTO heterostructure nanotube array was produced by combining a chemical solution process with oxygen-plasma etching. In this approach, presynthesized ZnO nanorod arrays act as templates, and FTO nanoparticles are deposited onto the ZnO nanorods by a simple spray pyrolysis method. X-ray photoelectron spectroscopy analysis demonstrated that the oxygen-plasma treatment decreased the O(2-)/OH(-) concentration ratio, resulting in dissociation of the Zn-O bonds and the outward diffusion of Zn cations to form an interior hollow, which is related to the formation of the hydroxyl functional group, Sn-OH, at the FTO surface. An etching evolution mechanism of the ZnO-FTO nanotubes via oxygen plasma was tentatively proposed in this study. Time-dependent photocurrent (I-T) measurements under ON-OFF cycles of UV illumination confirm that the 20-min etched sample exhibits a rectified photoresponse characteristic and a dark current increased by about 3 orders of magnitude over that of the unetched sample, which is attributed to the increased carrier concentration created at the surface conductive layer. This investigation offers an alternative selective etching method to lay the framework for nanoscale three-dimensional electrodes for solar-cell applications.

Fabrication and characterization of Mg-doped ZnO nanorod arrays.

Photoelectronic characteristics are investigated in well-aligned MgO-coated ZnO nanorods (MgO/ZnO nanocables) grown on Si substrates buffered with ZnO film at a low temperature by solution techniques. Transmission electron microscopy shows that a rough surface was observed for the MgO-coated ZnO nanorods due to deposition of MgO nanoparticles on the surface of the ZnO nanorods. However, after annealed at high temperatures, the surface of the MgO-coated ZnO nanorods was flattened to form Mg-doped ZnO nanorods. Photoluminescence spectra of Mg-doped ZnO nanorods displayed a blue shift of the near-band-edge emission with increasing annealing temperature indicative of an increase in the band gap of the MgZnO alloy due to diffusion of the Mg atoms into the ZnO nanorods. In contrast, no blue shift was detected for the samples annealed in H2/N2 (5%/95%) reduction atmosphere but a blue emission was detected at 800 degrees C, indicating that MgO diffusion process may produce a new luminescent center to emit the blue emission in H2/N2 reduction atmosphere.

Enhanced UV photoresponse in nitrogen plasma ZnO nanotubes.

The photoresponse behavior of one-dimensional ZnO nanowires (NWs) and nanotubes (NTs) grown on ITO-coated glass substrates via a wet-chemical route was investigated. The photoluminescence spectra exhibited a decrease in the deep-level intensity, indicating that the oxygen defects and impurities are occupied by the presence of N ions in the ZnO NT matrix after a nitrogen plasma treatment. I-V tests demonstrate an enhanced dark current (4.83 x 10(-7) A) after an extended plasma treatment of up to 900 s for ZnO NTs compared to that (0.571 x 10(-7) A) of NWs. Furthermore, the ZnO NTs show the highest reliable photoresponse, 20 times that of NWs under UV irradiation (325 nm) in air at room temperature. It is believed that nitrogen plasma ZnO nanotubes can potentially be useful in the designs of 1D ZnO-based solar cells and optoelectronic devices.

Electron transport behavior of individual zinc oxide coated single-walled carbon nanotubes.

Uniform zinc oxide coated single-walled nanotubes (SWNTs) were fabricated by ultrasonic irradiation with acid-treated SWNTs, zinc acetate, and triethanolamine at low temperature in aqueous phase processing. The ZnO coating process did not decrease the dark current of the SWNTs, but a real decrease in the steady state negative photocurrent was observed after ZnO coating, suggesting a clear photosensitization effect. Transport measurements reveal that the negative photocurrent in s (semiconducting)-SWNTs@ZnO could be described by electron-hole compensation behavior attributed to the ZnO layer under ultraviolet excitation. This simple coating method for one-dimensional material can open up new possibilities for multifunctional nanodevices.

Application of wastewater from paper and food seasoning industries with green manure to increase soil organic carbon: a laboratory study.

This laboratory scale experiment was designed to study the suitability of organic wastes from paper and food seasoning industries to improve the soil organic carbon for rice cultivation. Lignin-rich wastewater from paper industry and nitrogen-rich effluent from a food industry at suitably lower concentrations were used at two levels of green manure to enhance the soil organic carbon fraction over time. Both the groups of soils with or without Sesbania were incubated under submerged condition at 25 degrees C for 15 days. Wastewaters from paper industry (WP), food industry (WS), and a combination of WP+WS were added separately to both the treatment groups in flasks. After 103 days of incubation, from all the three treatments and control, total organic carbon and alkali-soluble organic carbon fractions were analyzed. Results indicated that in all the three treatments containing green manure amended with industrial wastewaters, the organic carbon content increased significantly. The alkali-soluble organic carbon fraction was increased by 59% in the soil amended with green manure containing WS and by 31% in the treatment without green manure compared to control. The paper mill waste water namely, WP, increased the organic carbon only in the soil containing green manure by 63%. The combined treatment of WP+WS with green manure increased alkali-soluble organic carbon fraction by 90% compared to control, while in the treatment without green manure, the organic carbon increase was 71%. Overall, the combined treatment WP+WS with green manure could increase the alkali-soluble organic carbon fraction more than all other treatments. Hence, wastewater rich in organics from paper and food industries can be efficiently used to temporarily increase the soil organic carbon content.

Nanohybrid structure analysis and biomolecule release behavior of polysaccharide-CDHA drug carriers.

Nanoscaled polymer composites were prepared from polysaccharide chitosan (CS) and Ca-deficient hydroxyapatite (CDHA). CS-CDHA nanocomposites were synthesized by in situ precipitation at pH 9, and the CS-CDHA carriers were then fabricated by ionic cross-linking methods using tripolyphosphate and chemical cross-linking methods by glutaraldehyde and genipin. Certain biomolecules such as vitamin B12, cytochrome c, and bovine serum albumin were loaded into the CS-CDHA carriers, and their release behaviors were investigated. Furthermore, these CS-CDHA carriers were examined by transmission electron microscopy, electron spectroscopy for chemical analysis, and X-ray diffraction. The release behavior of the biomolecules was controlled by the CS/CDHA ratios and cross-linked agents. By increasing the concentration of CS and the concentration of the cross-linking agents, cross-linking within carriers increases, and the release rate of the biomolecules is decreased. Moreover, the release rate of the biomolecules from the CS-CDHA carriers at pH 4 was higher than that at pH 10, displaying a pH-sensitive behavior. Therefore, these CS-CDHA hydrogel beads may be useful for intelligent drug release and accelerate bone reconstruction.

Synthesis and optical properties of white-light-emitting alumina/ZnO nanotubes.

A simple chemical solution process was used to prepare alumina nanoparticle-coated ZnO nanotubes (ANZTs). Transmission electron microscope (TEM) images proved that the alumina nanoparticles were uniformly dispersed on the ZnO nanotubes. After thermal treatment at different temperatures under various atmospheres, photoluminescence (PL) measurements showed that the ANZTs emitted a variety of colors, including blue, green and white light. Gaussian curve fitting of the PL spectra revealed that the competition between the blue, blue-green, green and yellow band emissions and their relative emission intensities were strongly associated with various defects. Blue emission was attributed to large numbers of oxygen defects in alumina, while green and yellow emissions were related to oxygen and zinc defects in ZnO, respectively. Under specific conditions, white light, consisting of blue, blue-green, green and yellow band emissions, was obtained. Further TEM analysis indicated that the defect structure of ANZTs could be manipulated by the interface interaction between alumina and the ZnO nanotubes.

Biofunctional ZnO nanorod arrays grown on flexible substrates.

A square pattern of thioctic acid self-assembled ZnO nanorod arrays was grown on a large 4-in. thermoplastic polyurethane (TPU) flexible substrate via an in situ soluthermal process at low temperature (348 K). With the addition of dimercaptosuccinic acid (DMSA), the surface chemistry forms a disordered ZnO phase, and the morphology of the ZnO-DMSA nanorods changes with various DMSA addition times. As evidenced by the Zn2p3/2, C1s, O1s, S2p, and N-1s scans of X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), DMSA and proteins were conjugated on the single crystalline ZnO nanorods. The photoluminescence (PL) spectra indicated that the optical properties of ZnO nanorod arrays were changed while the DMSA was inserted, and proteins were conjugated. Furthermore, a control test found that the ZnO nanorods show a significant improvement in sensitive characterization over the ZnO film. As another proteins (e.g., human serum albumin, HSA) were bound onto the ZnO-bovine serum albumin (BSA) nanorod arrays, an enhanced ultraviolet emission intensity was detected. On the basis of these results, one might be expected to conjugate specific biomolecules on the biofunctional ZnO nanorod arrays to detect the complementary biomolecules by PL detecting.