NOPR Collection:

Graphene oxide-supported gold nanocomposites for highly sensitive sandwich immunosensor for α-fetoprotein detection

2017-04-01T00:00:00Z

Title: Graphene oxide-supported gold nanocomposites for highly sensitive sandwich immunosensor for α-fetoprotein detection Authors: Li, Pengjun; Lai, Juanhua; Qiu, Ping Abstract: A graphene oxide-Au NPs sensor platform combined with a multiple-enzyme labeled detection antibody-carbon sphere bioconjugate has been used as the basis for an ultrasensitive electrochemical immunosensor to detect the cancer biomarker, α-fetoprotein (AFP). Greatly enhanced sensitivity has been achieved by using the bioconjugates featuring horseradish peroxidase (HRP) and Ab2 linked to carbon nanospheres (Ab2-HRP-Au-PDA-carbon sphere) at a high ratio of HRP/Ab2. After a sandwich immunoreaction, the Ab2-HRP-Au-PDA-carbon sphere captured onto the electrode surface produces an amplified electrocatalytic response due to the reduction of enzymatically oxidized thionine in the presence of hydrogen peroxide. The increase of response current is proportional to the AFP concentration in the range of 0.01-20 ng/mL, with the detection limit of 3 pg/mL. This amplification strategy is a promising platform for detection of other proteins and clinical applications. Page(s): 365-372

Microwave assisted transesterification of waste cooking oil over modified forms of zirconia coated on honeycomb monolith

2017-04-01T00:00:00Z

Title: Microwave assisted transesterification of waste cooking oil over modified forms of zirconia coated on honeycomb monolith Authors: Vasantha, V T; Shamshuddin, S Z Mohamed; Serrao, Reena Saritha; D’Souza, Joyce Queeny Abstract: Microwave assisted transesterification of waste cooking oil over honeycomb monoliths coated with zirconia based catalysts such as MgO/ZrO₂ and CaO/ZrO₂ to synthesize biodiesel is reported. For comparison, biodiesel synthesis via transesterification using conventional heating method has also been carried out. The solid acid Al₂O₃/ZrO₂ coated on a honeycomb has also been used as a catalyst to reduce the percentage of free fatty acid in waste cooking oil via esterification using conventional heating. The honeycomb monoliths have been coated with solid bases and characterized for their physico-chemical properties such as surface acidity, surface basicity, crystalinity and morphology using suitable techniques. The honeycomb monoliths coated with solid catalysts are found to be highly efficient and reusable in the process of synthesizing biodiesel from waste cooking oil. A maximum yield of biodiesel (98%) is obtained at 60 °C in 10 min by keeping the molar ratio of oil:methanol ratio at 1:6 under microwave irradiation. Page(s): 373-378

Catalytic activity of niobia supported graphene oxide for esterification of oleic acid

2017-04-01T00:00:00Z

Title: Catalytic activity of niobia supported graphene oxide for esterification of oleic acid Authors: Kanimozhi, S; Pandurangan, A; Hemalatha, P Abstract: Biodiesel has been obtained from esterification of oleic acid with methanol using niobia loaded graphene oxide (GO). Different weight percentages of niobia (1, 3, 5 and 7 wt.%) have been loaded on GO by the wet impregnation method. The synthesized materials have been characterized by XRD, FT-IR, Raman spectroscopy, TGA, BET surface area, NH₃-TPD, ICP-OES, SEM and HR-TEM studies. The catalytic activity of niobia supported on GO has been tested for esterification of oleic acid with methanol for biodiesel production. The maximum yield of methyl oleate (96.4%) is obtained at the reaction conditions of 150 °C, 0.5 g of 5 wt% of niobia on GO catalyst, 1:9 molar ratio of oleic acid:methanol and time 4 h. Influence of solvents (ethanol, propanol, butanol) has been tested for comparative study with same reaction conditions. Based on the catalytic studies, niobia supported GO has good catalytic activity for esterification of oleic acid reaction with good reusability. Page(s): 379-386

On the syntheses and structures of two calcium coordination polymers containing terminal amide ligands

2017-04-01T00:00:00Z

Title: On the syntheses and structures of two calcium coordination polymers containing terminal amide ligands Authors: Srinivasan, Bikshandarkoil R; Dhavskar, Kiran T Abstract: The syntheses and crystal structure of the calcium coordination polymers [Ca(NMF)₂(4-nba)₂] 1 (4-nba = 4-nitrobenzoate; NMF=N-methylformamide) and [Ca(BA)₂(4-nba)₂] 2 (BA= benzamide) is reported. A unique μ₂-η¹: η¹bridging bidentate 4-nba ligand links the hexacoordinated Ca(II) ions situated on a special position in both compounds into a one-dimensional (1-D) chain with Ca···Ca separations of 5.561 and 5.482 respectively. Each Ca(II) in the chain is bonded to a pair of symmetry related terminal amide ligands (NMF in 1; BA in 2) which are disposed trans to each other. A comparative study of several 4-nitrobenzoates of calcium is described. Page(s): 387-393