Issue 2

Deoxyribonucleic Acid Imprinted Biosensor Technology

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 85-85
DOI: 10.5185/amlett.2010.8111

In recent years, molecularly imprinted polymers (MIPs) have attracted much attention due to many of its potential applications including sensors, separation, catalysis, drug delivery and waste management. To prepare MIPs, functional monomers initially self-assemble around the template molecule via interaction between functional groups on both the template and the monomers. The self-assembled functional monomers are subsequently cross-linked in the presence of cross-linkers. Thereafter, the template molecules are removed from the MIPs, thereby leaving behind cavities/imprinted-structures that can specifically recognize and rebind with the template molecules, an analogy to the “key to lock” model. Hence, have the ability to mimic biological functions through their three-dimensional cavities of specific size, shape, and functionality for mimetic recognition of target molecules and have already shown valuable applications in the separation and recognition of glucose, cholesterol, hemoglobin, peptides, proteins, antibody, and double-stranded deoxyribonucleic acid (DNA).

Solid State Thermochromic Materials

Pragna Kiria; Geoff Hyett; Russell Binions

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 86-105
DOI: 10.5185/amlett.2010.8147

Solid-state thermochromic materials undergo semiconductor to metal transitions at a ‘critical temperature’, Tc. This review begins by describing the phenomenon of thermochromism, whereby the optical properties of a material change reversibly as a result of a change in temperature. The various different types of thermochromism will be introduced with a focus on the thermochromism exhibited by solid-state materials. The fundamental chemical principles that describe the electronic structure and properties of solids, and the chronological developments in the theory behind the thermochromic transitions (such as, the effects of electron-electron interactions and structural phase changes due to lattice distortions) that led to the discovery of the semiconductor-to-metal transition, are presented. An extensive discussion of vanadium and titanium oxides is presented with a particular focus on vanadium (IV) oxide since its transition temperature is closest to room temperature. Observations and current understanding of the nature of the semiconductor-to-metal transition exhibited by these materials is detailed. The possibility of fine-tuning the transition temperature by introducing various dopants into the vanadium (IV) oxide lattice is examined and the effects of dopant charge and size is examined. Solid-state thermochromic materials may be exploited in areas such as microelectronics, data storage, or intelligent architectural glazing, thus are required to be synthesised as thin films for use in such applications. The numerous synthetic techniques (PVD, sol-gel method, PLD, CVD, APCVD and AACVD), for making metal oxide thermochromic thin films are described in reference to the production of vanadium (IV) oxide and compared. Finally rare earth nickelates exhibiting thermochromism are described.

A Facile Fabrication Of Hydroxyapatite In Vitro Using Polymer Fasciculus As Biotemplate Carrier

Tao Yan; Dong Wei; Xianpeng Zheng; Xiaodong Xin; Nuo Zhang; Dan Wu; Liangguo Yan; He Li; Bin Du; Qin Wei

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 106-113
DOI: 10.5185/amlett.2010.4111

For biomimetic synthesis of hydroxyapatite by simulating biomineralization, the polyamide 66 (PA 66) was used as biotemplate carrier, and the biotemplate was prepared by the adsorption of AOT surfactants at interfaces of polymer fasciculus. Simulating biomineralization was carried out at physiological condition (pH = 7.4, T = 37 o C). The phase components, morphologies and possible growth mechanism of calcium phosphate were studied by fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results indicated that the course of crystal growth, as well as the morphology and composition of product was markedly dependent on biotemplate; the crystals size were within nanometer scope, with a sphere and short rod-like shape extraordinary close to natural bone. The possible mechanism of crystal growth was discussed.

Carboxy-eosin As A Marker For Correlative Light - Electron Microscopic Imaging Of Newly Synthesized In Vivo DNA

Alexandre Loukanov; Anatoli Angelov;Kuniaki Nagayama; Saim Emin; Surya P. Singh

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 114-117
DOI: 10.5185/amlett.2010.5127

Here we report carboxy-eosin as a fluorescent marker for in vivo visualization of DNA in the correlative (fluorescence and electron) biological microscope. For that purpose a fluorescent thymidine analog 2’,4’,5’,7’-tetrabromofluorescein-aminoallyl-dUTP (eosin-aminoallyl-dUTP) was synthesized and incorporated into the genome of Escherichia coli. The fluorescent dye eosin contains four bromine atoms, which enable electron spectroscopic imaging in the transmission electron microscope. Labeled cells were prepared and directly observed by fluorescence and electron microscope without any preliminary fixation step. We demonstrated that eosin-aminoallyl-dUTP is a suitable marker for imaging of cell’s ultrastructures by correlative biological microscopy.

Surface Patterning On Indium Phosphide With Low Energy Ar Atoms Bombardment: An Evolution From Nanodots To Nanoripples

Indra Sulania; Ambuj Tripathi; D. Kabiraj; Matthieu Lequeux; Devesh Avasthi

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 118-122
DOI: 10.5185/amlett.2010.5128

In the present study, Indium Phosphide (InP) (100) samples with a thickness of ~ 0.5 mm have been bombarded with 1.5 keV Argon atoms for a fixed fluence of 8 × 10 16 atoms/cm 2 . The angle of incidence of the atom beam has been varied from normal incidence to 76° with respect to surface normal. The bombarded surface shows the nanostructures as analysed by Atomic Force Microscopy (AFM). For normal and near normal incident angles of the beam, nanodots pattern have been observed and after a critical angle of incidence, the dots begin to align and with further increase of angle, nanostructures elongate along the beam direction. At 63° incidence, a well ordered ripple pattern has been reported. The evolution of nanostructures from nanodots to nanoripples has been analysed in terms of their size, shape and roughness by means of AFM imaging.

Synthesis, Characterization And Salt Resistance Swelling Behavior Of Psy-g-poly(AA) Hydrogel

Anjna Kumari; ;Susheel Kalia; Balbir Singh Kaith; Amar Singh Singha; and Susheel Kalia

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 123-128
DOI: 10.5185/amlett.2010.6129

Psyllium, a medicinally important natural polymer was functionalized with acrylic acid using FAS-H2O2 as redox initiator and glutaraldehyde as a crosslinker. Synthesized hydrogel was characterized with FTIR spectroscopy, SEM and TGA/DTA techniques to know their surface morphology and thermal stability. Salt resistant swelling behavior of synthesized hydrogel was studied in different salt solutions as a function of concentration of salt, temperature and pH. It was found that synthesized hydrogel showed maximum swelling (514.0 %) in NaCl solution followed by NH4Cl, MgCl2, CaCl2 and BaCl2 solution. Psy-g-poly(AA) hydrogel showed maximum swelling (863.49%) at 30 ºC in distilled water.

Synthesis And Characterization Of Highly Crystalline Polyaniline Film Promising For Humid Sensor

S.K. Shukla; Anand Bharadvaja; Ashutosh Tiwari; G.K. Parashar; G.C. Dubey

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 129-134
DOI: 10.5185/amlett.2010.3105

Polyaniline (PANI) was prepared in emeraldine via chemical oxidation method using CuSO4 as initiating agent. The chemical characterizations were made using UV-vis (ultraviolet-visible spectrophotometry), FT-IR (Fourier transform spectroscopy), TG-DTA (thermo-gravimetric/differential thermal analysis), ESI-MS (electrospray ionization mass spectrometry), XRD (X-ray diffraction), SEM (scanning electron microscopy) techniques. The results revealed the formation of homogeneous, crystalline PANI with sub-micron size particles. The PANI thin film of 0.5 µm thickness has been fabricated using spin coating technique. The resulting PANI film was exposed to controlled humid condition and change in resistance has been recorded. The resistance was continuously decreased from 13.5 to 3.75 MΩ with a linear change in humidity ranging from 3 to 95%. The result was reproducible and checked by repeating observation.

Effect Of Ultrasonic On The Properties Of Silicone/ Montmorillonite Nanocomposites By In-situ Intercalative Polymerization

Xinhua Yuan; Zhiwei Tian

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 135-142
DOI: 10.5185/amlett.2010.4119

Using ultrasonic technology, phenylmethylsilicone/organic montmorillonite (OMMT) nanocomposites were prepared by in-situ intercalative polymerization. The internal structure and morphology of nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. The basal spacing of OMMT increases with the increasing of ultrasonic time. Intercalated and exfoliated phenylmethylsilicone/OMMT nanocomposites were successfully prepared by convenient process of changing ultrasonic time for 15 min and 30 min, respectively. The barrier property for water was obviously improved by adding OMMT into silicone. The water absorption rate of intercalated nanocomposite containing 4wt% OMMT is 0.7687%, which is 10 times less than that of pure silicone. However, the water absorption rate of exfoliated nanocomposite is 2.802%, which is 3 times less than that of pure silicone. The nanocomposite containing 6wt% OMMT has the best mechanical performance. The impact strength of intercalated nanocomposite is 1.593 2 kJ/m 2 , which is enhanced 7.45% more than that of pure silicone, and the impact strength of exfoliated nanocomposite is improved 14.4% to 1.695 7 kJ/m 2 . The tensile strength of intercalated nanocomposite was markedly enhanced from 1.247 MPa of pure silicone to 7.021 MPa and to 6.264 MPa for exfoliated nanocomposite. When nanocomposite contains 4wt% OMMT, the compressive strength of pure silicone is also evidently improved from 2.834 MPa to 10.232 MPa of intercalated nanocomposite and to 11.503 MPa of exfoliated nanocomposite, respectively. The hardness of exfoliated and intercalated PLS nanocomposites are both firstly increased with the increasing of OMMT content, and then decreased, and finally increased again.

Polyphenylene Sulphide/graphite Composites For EMI Shielding Applications

Rajendra Kumar Goyal;Amol Kadam

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 143-147
DOI: 10.5185/amlett.2010.7136

Electrical properties of graphite flake (GF) filled polyphenylene sulphide (PPS) composites prepared by hot pressing was investigated to be used for electromagnetic interference (EMI) shielding applications. Composites exhibited an electrical conductivity percolation threshold of 5 wt%. The electrical conductivity of composites was increased fourteen orders of magnitude higher than that of pure PPS. The dielectric constants and dissipation factor of composites were measured in a frequency range of 100 KHz to 15 MHz. The dielectric constant of the composites increased several orders of magnitude and showed a strong dependence on frequencies. For example, dielectric constant of 8 wt% composite measured at 1 MHz was increased by five orders of magnitude compared to pure PPS. Similarly, dissipation factor was increased significantly. Scanning electron microscopy showed 3-dimensional conducting network of GF across the PPS matrix. Significant improvement in electrical properties shows that these composites may be useful for EMI shielding particularly at high temperature applications.

Synthesis Of Highly Soluble Phthalocyanine From A New Phthalonitrile Under Mild Conditions

Surya Prakash Singha; Saim Emin;Alexandre Loukanov

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 148-150
DOI: 10.5185/amlett.2010.5126

Novel syntheses of zinc phthalocyanine (ZnPc) are achieved by exploring our hexamethyldisilazane (HMDS) method. Reactions are clean and efficient by replacing harmful and strongly smelling triethylamine with HMDS. The compound is highly soluble in organic solvents and can be used as a donor material for organic thin film photovoltaic solar cells.

Tailoring The Size Of Gold Nanoparticles By Electron Beam Inside Transmission Electron Microscope

Y. K. Mishra; S. Mohapatra; D. K. Avasthi; N. P. Lalla; Ajay Gupta

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 151-155
DOI: 10.5185/amlett.2010.4116

Au nanoparticles (NPs) embedded in silica matrix were synthesized by atom beam co-sputtering and investigated in detail by transmission electron microscopy (TEM). A study on electron beam induced tailoring of size of Au nanoparticles has been performed in an in-situ TEM experiment as a function of electron irradiation time. This study concludes that electron beam irradiation can result in a controlled growth of NPs in proportion to irradiation fluence. Analytical calculations for electron energy loss in Au NPs and fused silica have been performed, which indicate that the observed growth of Au NPs in present case is due to rise in temperature of Au NPs and surrounding silica.

Enhancement Of Hydrophobic Character Of Lignocellulosic Fibers Through Graftcopolymerization

Amar Singh Singha;Raj K. Rana

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 156-163
DOI: 10.5185/amlett.2010.6134

Owing to hydrophilic behavior lignocellulosic fibers, e.g. Agave is unacceptable in various fields of applications. In the present communication attempts have been made to enhance hyrdrophobicity of these fibers through surface modification using methyl methacrylate as vinyl monomer. The grafting reaction initiated by ceric ion was carried out in vacuum. The various reaction parameters such as reaction time, temperature, monomer concentration, initiator concentration and vacuum were optimized to obtain the maximum percent graft yield. The grafted samples were evaluated for the hydrophobic character and other physico- chemical properties such as swelling behavior in different polar and nonpolar solvents alongwith chemical resistance behavior. The grafted products were further characterized by different techniques such as FT-IR, SEM, X-RD and thermogravimetric studies.

A High Throughput Chemiluminescence Method Based On Molecularly Imprinted Sol-gel Films For Determination Of Sibutramine

Fuwei Wan; Jinghua Yu; Shenguang Ge; Mei Yan; Kexiao Yu; Meng Zhang

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 164-169
DOI: 10.5185/amlett.2010.7138

A novel and high throughput chemiluminescence (CL) method for determination of sibutramine was originally developed based on potassium permanganate-hydrochloric acid-(tween-80) CL system. Molecularly imprinted sol-gel film (MIF) was synthesized and used as selective material to improve the selectivity of CL. In the proposed procedure, sibutramine molecule was adsorbed into the MIF, and then potassium permanganate, hydrochloric acid and tween-80 were added in wells of a 96-well plate, Based on which, sibutramine was oxidized and CL was produced and detected by a photomultiplier tube (PMT). The CL intensity was correlated linear with the concentration of sibutramine over the range of 5.0 × 10-8-1.0 × 10 -6 g ×mL -1   and the detection limit was 1.8 × 10 -8 g ×mL -1  . The relative standard deviation (RSD) was 3.1% for determination of 1.0 × 10 -7 g ×mL -1  sibutramine (n = 11). The fabricated molecularly imprinted sol-gel film possessed good selectivity and could be regenerated. This method was successfully applied to the determination of sibutramine in weight-reducing tonic.

ERRATUM To "Microwave Assisted Synthesis Of Chitosan-graft-styrene For Effecient Cr(VI) removal": [Adv. Mat. Lett. 2010, 1(1) 59-66]

Ajit Kumar Sharma;Ajay Kumar Mishra

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 170-177
DOI: 10.5185/amlett.2010.4120E

In this study, we have synthesized chitosan-grafted-styrene (Ch-g-sty) without any radical initiator or catalyst using microwave (MW) irradiation. Ch-g-sty was synthesized with 187% grafting using 80 % MW power in 40 second at (styrene) 0.13 M, (Chitosan) 0.1 g/25 mL. On the other hand, under similar condition of concentration of styrene and chitosan, 148% grafting was observed with potassium persulphate (K2S2O8)/ascorbic acid as redox initiator and atmospheric oxygen as co-catalyst in 1 h using conventional method at 35 o C. Microwave synthesized Ch-g-sty copolymer was characterized by Fourier transform-Infrared (FTIR) spectroscopy, thermo gravimetric analysis (TGA), X-ray diffraction (XRD) measurement and scanning electron microscopy (SEM). Maximum grafting was optimized by varying the microwave power, exposure time and styrene/chitosan concentration. Ch-g-sty copolymer was found to be more efficient for Cr(VI) removal as compare to conventionally and parent chitosan in aqueous solution. Sorption of Cr(VI) was depending upon pH and concentration, with pH=3 being the optimum value. The equilibrium data followed the Langmuir isotherm model with maximum capacities of 526.3 mg/g, 312.5 mg/g and 166.7 mg/g for Ch-g-sty copolymer, conventional (thermostatic water bath) method and parent chitosan respectively.