Micro and Nanosystems - Volume 7, Issue 2, 2015
Volume 7, Issue 2, 2015
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Research Highlight: Deoxyribonucleic Acid Based Nanotechnology
More LessDeoxyribonucleic acid (DNA) is the coding material in living organisms. Complementary pairs of nucleobases contribute to the Watson-Crick helical shape of DNA. The nucleobases are connected through hydrogen bonding. This unique feature not only allows for genetic information to be stored but also the assembly of complex nanostructures. DNA-based nanotechnology utilizes DNA as the engineering materials. DNA nanodevices can be designed to work as a drug carrier with programmable selectivity, sensor and computer. Since DNA is a natural material, the application of DNA nanodevices in a biological environment ranging from the relatively simple cell to a complex living organism is a complex, risky but rewarding task.
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Photochromic Effect of Copper Doped Nano Silver Chloride Impregnated Polyvinyl Alcohol thin Film
This report describes the photo chromic activity of nano silver chloride particles impregnated polyvinyl alcohol thin film fabricated by solvent casting method. The nano size silver chloride particles have been prepared by wet chemical route in the presence of polyvinyl pyrrolidone as a capping agent. Evaluation of the structural features of silver chloride and their polymer composites was performed by employing FTIR, SEM, AFM, UV-Vis. analysis and XRD data. AFM analysis reveals the size of silver chloride particles in the range of 80 nm. From the SEM image, the morphology of the nano particles used in this study has been explored. The XRD pattern of the prepared AgCl nano particles exhibits characteristic peaks in the X-ray diffraction corresponding to FCC geometry. The photochromic ability of the polymer matrix towards visible light has been examined through UV- visible spectrophotometer. The opaque state of the materials is observed when the polymer matrix was exposed to sunlight and turns transparent on keeping the substrate in the dark. The percentage of transmittance of the film during the exposure to sunlight and in the dark was measured and reported.
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Bioaffinity Mass Spectrometry Screening using Droplet-Based Microfluidics
Authors: Hoan Vu, Ronald J. Quinn and Nam-Trung NguyenBioaffinity mass spectrometry screening is a novel approach using non-denaturing electrospray ionization (ESI) mass spectrometry (MS) in identifying drug leads. This screening technique can detect and preserve noncovalent protein-active drug ligand complexes under different physiological conditions. Although there are many successful screening campaigns employing this technique, the big challenge of the screening is the reduction of sample volume needed. We demonstrate in this paper that analysis of samples can be performed using droplet-based microfluidics. Droplets of samples to be screened are formed and delivered directly into the electrospray emitter of a Fourier Transform mass spectrometer. The results show that a MS instrument with a conventional ESI source can clearly detect the samples and distinguish it with the separating oil phase. The proposed technique opens the possibility of bioaffinity mass spectrometry screening of small samples with a simple microfluidic device.
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Effect of TiO2 Loading Content on Properties of TiO2/HZSM-5 Photocatalyst
Authors: Wenjie Zhang, Chuanguo Li, Zheng Ma, Xijuan Chen and Hongbo HeTiO2 was supported on HZSM-5 using a sol-gel method. Anatase TiO2 phase is found in both pure TiO2 and the supported x%TiO2/HZSM-5 samples. The well distribution of TiO2 on the surface of HZSM-5 leads to shrinking crystallite size of anatase TiO2. After loading TiO2 on HZSM-5, surface area of the composite x%TiO2/HZSM-5 becomes much larger than that of pure TiO2. The 50%TiO2/HZSM-5 sample contains comparatively small pores in a narrow pore size range between 5-14 nm. The supported x%TiO2/HZSM-5 has enhanced photocatalytic activity as compared to pure TiO2. Full oxidation state of titanium does not change after loading TiO2 on HZSM-5, while electron binding energies of Ti2p1/2 and Ti2p3/2 shift to higher energy end. Photocatalytic degradation efficiency is 92.8% on 50%TiO2/HZSM-5 after 100 min of irradiation, which is much larger than the degradation efficiency of 66.1% on pure TiO2.
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The Significance of the Percentage Differences of Young’s Modulus in the AFM Nanoindentation Procedure
The application of the AFM nanoindentation procedure in order to determine the Young’s modulus values of specific nanoregions, results in many uncertainties, especially when biological samples are tested. This fact is due mainly to significant errors concerning the Young’s modulus calculation because physical parameters such as the spring constant of the cantilever and the exact shape and size of the tip provide uncertainties. Thus, the objective of this paper was to introduce a more accurate and simple approach of the nanoindentation technique by introducing the relative differences of Young’s modulus values. The new approach can be applied in measurements where the influence of a controlled external factor on a specific nanoregion is tested or variations in the mechanical properties of heterogeneous materials are investigated. The analysis was based on the general mathematical analysis which is used in the indentation procedure for the characterization of biological samples. The major advantage of the new technique is that it depends only on the cantilever’s deflection – displacement curves which can be obtained with great accuracy. In addition, in order to provide full insight in the new technique, the mechanical heterogeneity of collagen was examined. As a conclusion, when a sample is tested under the influence of a controlled external factor, or when inhomogeneous samples are tested, the determination of the percentage variations of the Young’s modulus is the most accurate parameter.
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Physicochemical Characterization and Clinical Evaluation of a Microemulsion System for Topical Delivery of Tazarotene in Psoriasis
Authors: Krutika K. Sawant, Piyush Mundada and Dhaval SodaniThe purpose of the present study was to evaluate the potential application of microemulsion as a dermal drug delivery system for a poorly water soluble drug-tazarotene and enhance its topical bioavailability. Various oils were screened based on solubility studies and isopropyl myristate was selected as the oil phase. Pseudo-ternary phase diagrams were developed for various microemulsion formulations composed of isopropyl myristate (oil phase), Tween 80 (surfactant), propylene glycol (cosurfactant) and water. The physicochemical properties and the permeability of tazarotene were investigated for the optimized microemulsion. This developed microemulsion was incorporated into Carbopol 934 based gel to facilitate its topical application. In-vitro drug diffusion of optimized formulation was studied using Franz diffusion cells. In-vitro drug diffusion after 8 h from the microemulsion incorporated gel was 72.01± 2.50%, while that from Tazret® (marketed product) was 61.59± 2.03%. Ex-vivo study using rat skin indicated that microemulsion incorporated gel had better skin deposition capacity (18.23± 1.00%) as compared to marketed formulation (7.23± 0.66%). The clinical efficacy of the test formulation was evaluated in psoriasis patients. Percent change in Psoriasis status after 6 weeks was 4.80± 1.74% and 17.36± 0.98% in treatment with ME incorporated gel and Tazret® respectively (p value < 0.05). The higher efficacy of the developed microemulsion system was attributed to the combined effect of increased solubility and reduced droplet size of microemulsion systems leading to increased deposition in the skin. The results suggest that microemulsions are potential vehicles for improved topical delivery of tazarotene to treat psoriasis.
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Monitoring of Sequentially Loaded Reagents to a Detection Area in a Microfluidic Chip
This paper presents a new scheme for monitoring the sequential loading of reagents to a detection site to conduct biological assays. The automation of the sequential loading of biological reagents to a detection site is monitored by a lens-less charged couple device (CCD). The fluid handling system employs a custom edge detection algorithm to determine the location of the channel edges. This custom edge detection method outperformed the built in Matlab edge detection functions. A parametric study was performed to determine the effects wavelength, height above a detection site, and voltage of a light emitting diode (LED), would have on the systems performance. A white light emitting diode, a voltage of 2.6V and a height of at least 20mm above the detection produced the best results. The fluid handling system was also able to work with channels that had different geometric designs and with different types of fluid. This research focuses for the first time on the monitoring of sequentially loading reagents to a detection site using a CCD imager that is also used for detection.
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Synthesis and Characterisation of Aminoplast Microcapsules for Controlled Release of Bioactives. Influence of the Resin:Oil Ratio
In this study a series of melamine-formaldehyde (MF) microcapsules containing Melaleuca alternifolia oil as natural biocide with different polymer to oil ratio was prepared by the in situ polymerization (O/W) method. The characterization of the microcapsules properties was undertaken by different experimental techniques in order to establish a correlation between the polymer to oil ratio and the oil encapsulation efficiency and properties for further applications. The average size distribution was determined by Laser Diffraction Scattering (DLS) and the chemical structure by Fourier Transformed Infrared Spectroscopy (FTIR). The morphology was characterized by Scanning Electron Microscopy (SEM). Finally, the thermal stability of microcapsules and the permeability of the shell to the diffusion of the core material were analyzed by Thermogravimetric Analysis (TGA). The obtained results showed that the resin:oil ratio was critical in the microcapsule formation and properties. For lower values than the critical one there was no microcapsule formation. For values over the critical resin:oil ratio value microcapsules were formed with spherical morphologies of varying wall thickness and oil encapsulation.
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First Principle Study of Oxygen Diffusion on Uranium Nitride UN (001) Surface with Uranium or Nitrogen Vacancies
Authors: T. Zergoug, S. E.H. Abaidia and A. NedjarMolecular and atomic oxygen diffusion on uranium mononitride UN(001) surface was studied. The more favorable bridge site corresponding to the oxygen diffusion on UN(001) clean surface was then checked under several surface states such as UN(001) surfaces including uranium or nitrogen vacancies. First principle calculation based on density functional theory (DFT) was used with the generalized gradient approximation (GGA) to describe the exchangecorrelation and the projector-augmented wave (PAW) as pseudo potential. Molecular and atomic potential energy surfaces (PES) corresponding to the interaction between respective molecular (O2) or atomic oxygen (O) and UN(001) surface states at several positions of the surface were used to study and identify the more favorable adsorption sites. The dissociation of molecular oxygen approaching UN(001) surfaces both clean or defected was proved for different orientation of the molecule with both atoms adsorbed on the surfaces. The more ability of oxygen adsorption on UN(001) nitrogen vacancy surface compared to other UN(001) surfaces states was confirmed. Considering more N vacancies on UN(001) surface and more O atoms diffusion, our results show that adsorption energies per O atom decrease with the rise in N vacancies and increase with increasing O atoms diffusion.
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