Conjugation of curcumin with PVP capped gold nanoparticles for improving bioavailability

Curcumin, a natural polyphenolic compound, has astounding therapeutic applications but lacks in bioavailability mainly due to its poor solubility in water. Polyvinyl pyrrolidone (PVP) which is a proven drug carrier has been used to facilitate the conjugation of curcumin with gold nanoparticles and to improve the solubility of curcumin in water. In this conjugate diaryl heptanoid chromophore group of curcumin which is a much needed group in biomedical applications remains intact as observed from FTIR and UV–vis spectroscopy analysis. The work shows good promise for such conjugates as therapeutic-cum-imaging materials in biomedical field.     

Molecular dynamics study on growth of carbon dioxide and methane hydrate from a seed crystal

In the current work, molecular dynamics simulation is employed to understand the intrinsic growth of carbon dioxide and methane hydrate starting from a seed crystal of methane and carbon dioxide respectively. This comparison was carried out because it has relevance to the recovery of methane gas from natural gas hydrate reservoirs by simultaneously sequestering a greenhouse gas like CO₂. The seed crystal of carbon dioxide and methane hydrate was allowed to grow from a super-saturated mixture of carbon dioxide or methane molecules in water respectively. Two different concentrations (1:6 and 1:8.5) of CO₂/CH₄ molecules per water molecule were chosen based on gas–water composition in hydrate phase. The molecular level growth as a function of time was investigated by all atomistic molecular dynamics simulation under suitable temperature and pressure range which was well above the hydrate stability zone to ensure significantly faster growth kinetics. The concentration of CO₂ molecules in water played a significant role in growth kinetics, and it was observed that maximizing the CO₂ concentration in the aqueous phase may not result in faster growth of CO₂ hydrate. On the contrary, methane hydrate growth was independent of methane molecule concentration in the aqueous phase. We have validated our results by performing experimental work on carbon dioxide hydrate where it was seen that under conditions appropriate for liquid CO₂, the growth for carbon dioxide hydrate was very slow in the beginning.     

Log-Space Algorithms for Paths and Matchings in k-Trees

Reachability and shortest path problems are NL-complete for general graphs. They are known to be in L for graphs of tree-width 2 (Jakoby and Tantau in Proceedings of FSTTCS’07: The 27th Annual Conference on Foundations of Software Technology and Theoretical Computer Science, pp. 216–227, 2007). In this paper, we improve these bounds for k-trees, where k is a constant. In particular, the main results of our paper are log-space algorithms for reachability in directed k-trees, and for computation of shortest and longest paths in directed acyclic k-trees. Besides the path problems mentioned above, we also consider the problem of deciding whether a k-tree has a perfect matching (decision version), and if so, finding a perfect matching (search version), and prove that these two problems are L-complete. These problems are known to be in P and in RNC for general graphs, and in SPL for planar bipartite graphs, as shown in Datta et al. (Theory Comput. Syst. 47:737–757, 2010). Our results settle the complexity of these problems for the class of k-trees. The results are also applicable for bounded tree-width graphs, when a tree-decomposition is given as input. The technique central to our algorithms is a careful implementation of the divide-and-conquer approach in log-space, along with some ideas from Jakoby and Tantau (Proceedings of FSTTCS’07: The 27th Annual Conference on Foundations of Software Technology and Theoretical Computer Science, pp. 216–227, 2007) and Limaye et al. (Theory Comput. Syst. 46(3):499–522, 2010).     

Effect of silicone dioxide and poly(ethylene glycol) on the conductivity and relaxation dynamics of poly(ethylene oxide)–silver triflate solid polymer electrolyte

The conducting and relaxation dynamics of Ag⁺ ions in poly(ethylene oxide) (PEO)–silver triflate (AgCF₃SO₃) solid polymer electrolytes (SPEs) containing nanosize SiO₂ filler and poly(ethylene glycol) (PEG) as a plasticizer were studied in the frequency range 10 Hz to 10 MHz and in the temperature range 303–328 K. The comparatively lower conductivity of the plasticized (PEG) PEO–AgCF₃SO₃–SiO₂ nanocomposite electrolyte system was examined by analysis of the Fourier transform infrared (FTIR) spectroscopy and conductivity data. The electric modulus (M″) properties of the SPE systems were investigated. A shift of the M″ peak spectra with frequency was found to depend on the translation ion dynamics and the conductivity relaxation of the mobile ions. The value of the conductivity relaxation time was observed to be lower for the PEO–AgCF₃SO₃ system only with nanofiller SiO₂. The scaling behavior of the M″ spectra showed that the dynamical relaxation processes was temperature-independent in the PEO–AgCF₃SO₃ and PEO–AgCF₃SO₃–SiO₂–PEG polymer systems, whereas they were temperature-dependent for the PEO–AgCF₃SO₃–SiO₂ system. However, the relaxation processes of all of theses systems were found to be dependent on their respective compositions. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Ag-polyaniline nanocomposite cladded planar optical waveguide based humidity sensor

The paper reports synthesis of Ag-polyaniline nanocomposite and its evaluation as an active optical cladding on a planar optical waveguide (POW) as a humidity sensor with variable concentration of the composite. The nanocomposite is dispersed in acetonitrile, and spin coated on the planar waveguide to form a clad. The system shows response to humidity, when tested in the range of 20–92% relative humidity (RH). A prism film coupling is used to characterize the cladded waveguide. The maximum sensitivity is seen for 47% concentration of the nanocomposite in acetonitrile. The response and recovery of the sensor are 8 and 55 s respectively. The low hysteresis is exhibited by the sensor. The sensor has repeatability and reproducibility. Material characterization is done using Scanning Electron Micrograph (SEM), X-Ray Diffraction (XRD), Ultraviolet Spectroscopy (UV) and Fourier Transform Infrared Spectroscopy (FTIR).     

Development of surface engineered mesoporous alumina nanoparticles: drug release aspects and cytotoxicity assessment

The present investigation deals with successful synthesis and surface functionalisation of mesoporous alumina (MeAl) nanoparticles by simplified sol–gel method using cetyl trimethyl ammonium bromide (CTAB) and pluronic as a template. Surface functionalisation of MeAl was performed to determine the selectivity of surface groups for coupling with model drug molecule. Repaglinide a BCS class II drug was loaded as a model drug on synthesised MeAl nanoparticle and studied for its sustained release capability. The synthesised and repaglinide loaded MeAl nanoparticles were characterised by Fourier transform infrared Spectroscopy, X‐ray diffraction, field emission scanning electron microscopy with EDAX, Transmission electron microscopy and differential scanning calorimetric. Results from the dissolution study confirmed the sustained release behaviour of the nanparticles which was up to 24 h. The cell viability assay demonstrated that 0.2 to 1 mg/ml concentration of MeAl was significantly less cytotoxic to the Chinese Hamster Ovary (CHO) cells. The authors’ experimental studies suggest that MeAl can be used as drug carrier and have a potential to increase the stability, loading efficiency and patient compliance for poorly water‐soluble drugs such as repaglinide.Inspec keywords: mesoporous materials, nanoparticles, nanomedicine, alumina, surface chemistry, cellular biophysics, toxicology, sol‐gel processing, Fourier transform infrared spectra, field emission electron microscopy, X‐ray chemical analysis, transmission electron microscopy, drug delivery systemsOther keywords: surface engineered mesoporous alumina nanoparticles, drug release aspects, cytotoxicity assessment, surface functionalisation, sol–gel method, cetyl trimethyl ammonium bromide, CTAB, pluronic, MeAl, model drug molecule, repaglinide, BCS class II drug, Fourier transform infrared spectroscopy, X‐ray diffraction, field emission scanning electron microscopy, EDAX, transmission electron microscopy, differential scanning calorimetry, cell viability assay, Chinese Hamster Ovary cells, drug carrier, poorly water‐soluble drugs, Al₂ O₃      

Effect of degree of deacetylation on solubility of low‐molecular‐weight chitosan produced via enzymatic breakdown of chitosan

Chitosan has emerged as a unique biomaterial, possessing scope in diverse applications in the biomedical, food and chemical industries. However, its high molecular weight is a concern when handling the polymer. Various techniques have been explored for depolymerization of this polymer, wherein enzymes have emerged as the most economic method having minimum degrading effect on the polymer and resulting in formation of side products. Chitosan can be depolymerized using a broad range of enzymes. In this study, various enzymes like α‐amylase, papain, pepsin and bromelain were employed to depolymerize chitosan and convert it into its lower molecular weight counterpart. Further, attempts were made to elucidate the process of depolymerization of chitosan, primarily by determining the change in its viscosity and hence its molecular weight. The process of depolymerization was optimized using a one‐factor‐at‐a‐time approach. The molecular weight of the resultant chitosan was estimated using gel permeation chromatography and infrared spectroscopy. These studies revealed a considerable decrease in molecular weights of chitosan depolymerized by pepsin, papain, bromelain and α‐amylase, resulting in recovery of the low‐molecular‐weight chitosan of 76.09 ± 5, 74.18 ± 5, 55.75 ± 5 and 49.18 ± 5%, respectively. Maximum yield and depolymerization were obtained using pepsin and papain due to their enzymatic recognition pattern, which was also validated using studies involving molecular dynamics. © 2019 Society of Chemical Industry     

Multifaceted Application of Silica Nanoparticles. A Review

Silicon - Nanoparticles have immense industrial, biotechnological, and biomedical/pharmaceutical applications due to their pliability in structure, size, biocompatibility, high surface area, and...     

An experimental and kinetic modeling study of 2-methyltetrahydrofuran flames

Clean combustion processes are of paramount importance in the transition of the energy system towards increased sustainability. In an attempt to partially replace conventional fossil fuels, bio-derived oxygenates attract rising attention as alternative transportation fuels. Among this class of fuels, cyclic structures that can be derived from cellulosic biomass are particularly interesting. Here we present a study of premixed, laminar low-pressure flames of 2-methyltetrahydrofuran (2-MTHF) with an equivalence ratio of ? = 1.7 at 40 mbar. Time-of-flight molecular-beam mass spectrometry (MBMS) with electron ionization (EI) was used to analyze and quantify mole fraction profiles of reactants, products, and most intermediate species including radicals involved in the combustion process. As a valuable complement, MBMS using single-photon ionization (PI) by vacuum ultraviolet radiation permitted isomer identification as well as independent concentration information under similar flame conditions. A detailed combustion model for 2-MTHF was developed, and the flame structure and species information were examined in conjunction with these experiments.     

Nano-bitter gourd like structured CuO for enhanced hydrogen gas sensor application

Hydrogen gas sensing were investigated using nano-bitter gourd like structured CuO material synthesized via a chemical route. Morphology of CuO was revealed using FE-SEM and TEM image analysis. CuO phase confirmation and molecular structural fingerprint were verified by XRD and Raman analysis respectively. Elemental composition and atomic states of elements were investigated by EDS and XPS techniques respectively. A remarkable high gas response of 175% was recorded by CuO sensor towards 100 ppm hydrogen (H₂) at the operating temperature 200 °C with response time 150 s. The lowest detection of H₂ was observed at 2 ppm concentration with the gas response of 5%. The gas response was studied as functions of different operating temperatures and concentrations. Transient gas response and stability were also confirmed for CuO sensor. Hydrogen sensing mechanism of CuO sensor was elucidated.