Preparation of a specific monoclonal antibody to asiaticoside for the development of an enzyme-linked immunosorbent assay

Asiaticoside (AS), the major active component of Centella asiatica (L.) Urban, is used as a memory enhancer and for wound healing. We have successfully prepared monoclonal antibodies (MAbs) against AS, and developed an enzyme-linked immunosorbent assay (ELISA) system for its determination. AS was conjugated to the carrier protein bovine serum albumin (BSA), which acted as an immunogen. In order to confirm its immunogenicity, the ratio of hapten in the AS-BSA conjugate was determined by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). After immunization, hybridomas secreting MAbs against AS were produced by fusing splenocytes with the mouse myeloma cell line, SP2/0-Ag14. After the screening, anti-asiaticoside MAb 2B4 was obtained. Weak cross-reactivities occurred with madecassoside (7.08%), but no cross-reactivities were observed with other related triterpenoid glycosides (<0.01%). The assay was suitable for quantitating AS in the range of 0.78 to 50 μg mL(-1). A good correlation of AS concentrations in crude extracts of C. asiatica between ELISA and HPLC methods was obtained (r(2) = 0.999). The contents of AS in various cultivated C. asiatica samples were assayed by the newly established ELISA. The recovery rates of AS in the samples were in the range of 95-103% with coefficients of variation of <10%. The intra- and inter-assay variations were 3.9 and 4.5%, respectively. The ELISA method described should prove useful as an analytical tool for quality control and standardization of medicinal plants and pharmaceutical products containing AS.     

Nanofibers of barium strontium titanate (BST) by sol-gel processing and electrospinning

This paper describes the fabrication of barium strontium titanate (Ba0.6Sr0.4TiO3 or BST) nanofibers by electrospinning method using a solution that contained poly(vinylpyrrolidone) and a sol-gel solution of BST. The as-spun and calcined BST/PVP composite nanofibers were characterized by TG-DTA, X-ray diffraction, FT-IR, SEM and TEM, respectively. After calcination of the as-spun BST/PVP composite nanofibers at above 700 degrees C in air for 2 h, BST nanofibers of 188+/-25 nm in diameter having well-developed cubic-perovskite structure were successfully obtained. The crystal structure and morphology of the nanofibers were influenced by the calcination temperature. Calcination at below 700 degrees C resulted in amorphous phase whereas BST with second phase such as barium titanate were formed at above 700 degrees C. Diameters of the nanofibers decreased from 208+/-35 to 161+/-18 nm with increasing calcination temperature between 600 and 800 degrees C.     

Investigation of structural,morphological, optical,and magnetic properties of Sm-doped LaFeO3 nanopowders prepared by sol–gel method

Journal of Sol-Gel Science and Technology - Pure orthorhombic phase of La1?xSmxFeO3 (x?=?0, 0.1, 0.2, and 0.3) nanoparticles can be obtained by sol–gel method after...     

Structure,optical and magnetic properties of LaFeO3 nanoparticles prepared by polymerized complex method

This work reports the study the structure, optical and magnetic properties of LaFeO₃ nanoparticles synthesized by the polymerized complex method. The LaFeO₃ nanoparticles were successfully obtained from calcination of the precursor at different temperatures from 750 to 1,050 °C in air for 2 h. The calcined LaFeO₃ nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–Visible spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge spectroscopy (XANES) and vibrating sample magnetometry. The XRD and TEM results showed that all LaFeO₃ samples had a single phase nature with the orthorhombic structure. The estimated crystallite sizes were in the range of 44.5 ± 2.4–74.1 ± 4.9 nm. UV–Vis spectra showed strong UV and Vis absorption with small band gap energy. The valence states of Fe ions were in the Fe³⁺ and Fe⁴⁺ state, as confirmed by XPS and XANES results. The weak ferromagnetic behavior with specific saturation magnetization of 0.1 emu/g at 10 kOe was obtained for the small particle of 44.5 ± 2.4 nm. The uncompensated spins at the surface was proposed as playing a part in the magnetic properties of small sized LaFeO₃.     

Structure and magnetic properties of Zn<Subscript>0.9</Subscript>Co<Subscript>0.1</Subscript>O nanorods synthesized by a simple sol–gel method using metal acetylacetonate and poly(vinyl alcohol)

Room-temperature ferromagnetism was observed in Zn_0.9Co_0.1O nanorods with diameters and lengths of ∼100–200 nm and ∼200–1000 nm, respectively. Nanorods were synthesized by a simple sol–gel method using metal acetylacetonate powders of Zn and Co and poly(vinyl alcohol) gel. The XRD, FT-IR and SAED analyses indicated that the nanorods calcined at 873–1073 K have the pure ZnO wurtzite structure without any significant change in the structure affected by Co substitution. Optical absorption measurements showed absorption bands indicating the presence of Co²⁺ in substitution of Zn²⁺. The specific magnetization of the nanorods appeared to increase with a decrease in the lattice constant c of the wurtzite unit cell with the highest value being at 873 K calcination temperature. This magnetic behavior is similar to that of Zn_0.9Co_0.1O nanoparticles prepared by polymerizable precursor method. We suggest that this behavior might be related to hexagonal c-axis being favorable direction of magnetization in Co-doped ZnO and the 873 K (energy of 75 meV) being close to the exciton/donor binding energy of ZnO.     

A simple synthesis and magnetic behavior of nanocrystalline Zn0.9Co0.1O powders by using Zn and Co acetates and polyvinyl pyrrolidone as precursors

This paper reports the synthesis of nanocrystalline powders of Co-doped ZnO (i.e. Zn_0.9Co_0.1O (ZCO)) diluted magnetic semiconductor by a simple method using acetate salts of Zn and Co, and polyvinyl pyrrolidone as precursors. The morphology and crystalline size of the synthesized powders were evaluated by scanning electron microscopy and transmission electron microscopy (TEM). The ZCO powders consist of both nanoparticles with particle sizes of ∼50–100 nm and nanorods with diameters of ∼100–200 and ∼200–500 nm in length. The X-ray diffraction and TEM results indicated that the synthesized ZCO powders had the pure wurtzite structure without any significant change in the structure affected by Co substitution. Optical absorption measurements showed absorption bands indicating the presence of Co ions in substitution of Zn ions. Room-temperature magnetization results revealed a paramagnetic behavior for the ZCO precursor (as grown sample) and a ferromagnetic behavior for the ZCO powders calcined in air at 873 K for 1 h.     

Synthesis of ACAT inhibitors through substitution using allylic picolinate and copper reagent

Amide of an octanoic acid possessing an aryl group at C3 position is a highly potent ACAT inhibitor. In this paper, we describe a synthetic access to this class of compounds as optically active forms. The key reaction is substitution of the allylic picolinate of (S,Z)-8-(benzyloxy)oct-5-en-4-ol with a copper reagent derived from (benzo[d][1,3]dioxol-4-yl)MgBr and CuBr·Me₂S to produce anti S_N2′ product regio- and stereo-selectively. The product was hydrogenated to afford (S)-3-benzo[d][1,3]dioxol-4-yloctan-1-ol, which upon oxidation furnished the octanoic acid. Finally, the acid was converted with 2,6-(i-Pr)₂C₆H₃NH₂ to the target amide via acid chloride. In a similar way, the one-carbon long homolog was synthesized.