Sineenat Siri

Magnetic and Cytotoxicity Properties of La1−xSrxMnO3(0 ≤ x ≤ 0.5) Nanoparticles Prepared by a Simple Thermal Hydro-Decomposition

This study reports the magnetic and cytotoxicity properties of magnetic nanoparticles of La1−xSrxMnO3(LSMO) withx = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 by a simple thermal decomposition method by using acetate salts of La, Sr, and Mn as starting materials in aqueous solution. To obtain the LSMO nanoparticles, thermal decomposition of the precursor was carried out at the temperatures of 600, 700, 800, and 900 °C for 6 h. The synthesized LSMO nanoparticles were characterized by XRD, FT-IR, TEM, and SEM. Structural characterization shows that the prepared particles consist of two phases of LaMnO3(LMO) and LSMO with crystallite sizes ranging from 20 nm to 87 nm. All the prepared samples have a perovskite structure with transformation from cubic to rhombohedral at thermal decomposition temperature higher than 900 °C in LSMO samples ofx ≤ 0.3. Basic magnetic characteristics such as saturated magnetization (MS) and coercive field (HC) were evaluated by vibrating sample magnetometry at room temperature (20 °C). The samples show paramagnetic behavior for all the samples withx = 0 or LMO, and a superparamagnetic behavior for the other samples havingMSvalues of ~20–47 emu/g and theHCvalues of ~10–40 Oe, depending on the crystallite size and thermal decomposition temperature. Cytotoxicity of the synthesized LSMO nanoparticles was also evaluated with NIH 3T3 cells and the result shows that the synthesized nanoparticles were not toxic to the cells as determined from cell viability in response to the liquid extract of LSMO nanoparticles.

Different properties of electrospun fibrous scaffolds of separated heavy-chain and light-chain fibroins of Bombyx mori

This study is the first to report on the fabrication and properties of electrospun scaffolds derived from separated light-chain fibroin and heavy-chain fibroin, two major proteins of silk fibroin. Among seven different extraction conditions, which were commonly used to extract fibroin from cocoons of Bombyx mori, only Ajisawas reagent and 9 M lithium thiocyanate could extract both heavy-chain fibroin and light-chain fibroin, while the other conditions could yield only the light-chain fibroin. Mixed fibroin, light-chain fibroin, and heavy-chain fibroin were fabricated using electrospinning methods. Average diameters of the fibers were 658+/-208, 517+/-162, and 518+/-171 nm, respectively and their sizes after treatment with 50% methanol for 60 min were slightly increased to 747+/-244, 556+/-164 and 521+/-201 nm, respectively. FTIR spectra showed similar predominant beta-sheet conformation of mixed fibroin and heavy-chain fibroin scaffolds after treated with methanol, whereas the predominant structure of light-chain fibroin was random coil conformation. Although, scaffolds derived from mixed fibroin and heavy-chain fibroin showed similar properties, the light-chain fibroin scaffold clearly exhibited different properties, including more hydrophilic character, water uptake ability, degradation rate, and cell adhesion capability.

Surface modification of electrospun PCL scaffolds by plasma treatment and addition of adhesive protein to promote fibroblast cell adhesion

Abstract Nanofibres fabricated from synthetic polymers via electrospinnning may be uniform and possess consistent quality; however, due to the nature of polymers, these nanofibres may not serve as suitable substrates for cell adhesion. Thus, the present work is aimed to enhance cell adherence onto the as spun poly(ϵ-caprolactone) (PCL) scaffolds via simple protein absorption, air plasma treatment and protein immobilisation methods. The as spun PCL fibres had average fibre diameter of 475·99 ± 194·52 nm with average porosity of 72·29 ± 1·90%. The laminin absorbed scaffold exhibited 20% increase in cell adhesion compared to the original scaffold. With the plasma treatment, the scaffolds increased their fibre sizes, but no significant change occurred in their porosities. The as spun PCL scaffold treated with air plasma was less hydrophobic and exhibited 66% increase in cell adherence compared to the original scaffold. When laminin protein was also included, a greater increase in cell adhesion was observed (84%). Comparing all methods, a laminin immobilised scaffold, with argon/oxygen plasma treatment followed by protein grafting with acrylic acid, showed the highest result of cell adhesion (96%). The results of the present work demonstrate the comparison of various means of using plasma treatment and laminin protein to enhance cell adherence onto the as spun PCL scaffolds, making it more suitable for tissue engineering and wound dressing applications.

Suppression of growth and cancer‐induced angiogenesis of aggressive human breast cancer cells (MDA‐MB‐231) on the chorioallantoic membrane of developing chicken embryos by E‐peptide of pro‐IGF‐I

E‐peptide of the pro‐Insulin‐like growth factor‐I (pro‐IGF‐I) is produced from pre‐pro‐IGF‐I by proteolytic cleavage in the post‐translational processing. Previous in vitro studies conducted in our laboratory showed that Ea4‐peptide of rainbow trout (rt) pro‐IGF‐I or Eb‐peptide of human (h) pro‐IGF‐I exhibited activities including induction of morphological differentiation, inhibition of anchorage‐independent cell growth and suppression of invasion of several well established human cancer cell lines such as MDA‐MB‐231, HT‐29, SK‐N‐F1, and HepG‐2 (Chen et al. [2002] Gen Comp Endocrinol 126:342–351; Kuo and Chen [2002] Exp Cell Res 280:75–89). Seeding of aggressive human breast cancer cells, MDA‐MB‐231, on the chorioallantoic membrane (CAM) of 5 days old chicken embryos resulted in rapid growth and invasion of the cells and induction of blood vessel formation around the MDA‐MB‐231 cell mass in the chicken embryos. The invasion of MDA‐MB‐231 cells in the chicken embryos was further confirmed by immunocytochemistry. The rapid growth and invasion of MDA‐MB‐231 cells and the induction of blood vessel formation by MDA‐MB‐231 cells on chicken CAM are inhibited by treatment with a single or multiple doses of rtEa4‐ or hEb‐peptide. Furthermore, a dose‐dependent inhibition of angiogenesis by rtEa4‐ or hEb‐peptide was also demonstrated by the chicken CAM assay. Results of microarray analysis of human gene chips (containing 9,500 unique cDNA clones) and confirmation by comparative real‐time RT‐PCR analysis showed that a group of genes related to cancer cell activities are up‐ or down‐regulated in MDA‐MB‐231 cells transfected with a rtEa4‐peptide gene. Together these results confirm the anti‐tumor activity of rtEa4‐ and hEb‐peptides, and further suggest that these peptides could be developed as therapeutics for treating human cancers. J. Cell. Biochem. 101:1316–1327, 2007.

Alternative biomaterials: natural, non-woven, fibroin-based silk nanofibers of weaver ants (Oecophylla smaragdina).

Silks of silkworms and spiders have been widely studied as biomaterials, however, none has been reported on silks produced by weaver ants (Oecophylla smaragdina). This study is the first to report on some properties of natural silk fibers of weaver ants and their potential application as a cell matrix. Weaver ant fibrous mat contained non-woven mesh of fibers with diameters ranging from 266 to 3056 nm. The average diameter of fibers was 766+/-326 nm. The thickness, mass, and apparent density of the fibrous mats were 39.0+/-9.8 microm, 0.8+/-0.1 mg/cm2, and 0.22+/-0.03 g/cm3, respectively. Freshly made fibrous mats by weaver ants were highly hydrophilic as determined by water contact angle analysis, whereas older ones were quite hydrophobic. TG-DTA analysis revealed a major weight loss peak from 260 up to about 330 degrees C, similar to the decomposition peak of Bombyx mori fibroin. FT-IR spectrum showed amide I, amide II, amide III, C-H and C-O peaks, which were attributed to random coil and beta-sheet conformation in the protein structure of the weaver ant fibers. The fibrous mat was slight toxic to the fibroblast NIH 3T3 cells (37.8% cell death), probably due to some toxic particles deposited on the fibers. Nevertheless, weaver ant fibrous mat served as a good matrix for cell adhesion. Results of this work provided evidence for the properties and a potential application of natural weaver ant fibers as an alternative, natural, fibroin-based matrix.

Repetitive Arg‐Gly‐Asp peptide as a cell‐stimulating agent on electrospun poly(ϵ‐caprolactone) scaffold for tissue engineering

Electrospun scaffolds derived from poly(ϵ-caprolactone) (PCL), a well known biodegradable material, have an architecture that is suitable for hosting cells. However, their biomedical applications are restricted because these scaffolds lack the bioactivity necessary to stimulate cell responses. In this work, a repetitive Arg-Gly-Asp (rRGD) peptide was produced as a cell-stimulating agent to provide the PCL scaffold with bioactivity. DNA encoding rRGD was amplified by polymerase chain reaction using overlap primers without a DNA template, and cloned into a protein expression vector to produce a His-tag fusion peptide. In an in vitro cell adhesion assay, the purified rRGD peptide, comprising 30 RGD repeats, promoted a 1.5-fold greater cell adhesion than the commercial tripeptide RGD. The rRGD peptide was immobilized onto an electrospun PCL scaffold that had been pretreated with argon plasma and graft-polymerized with acrylic acid. Fourier transform infrared (FTIR) analysis indicated that covalently linked rRGD peptide was present on the scaffold. The PCL scaffold with immobilized rRGD showed significantly changed hydrophilic properties and an enhanced adhesion and proliferation of mouse fibroblast cells by 2.3- and 2.9-fold, respectively, compared to the PCL scaffold alone. Through its ability to promote cell adhesion and proliferation, the rRGD peptide has great potential as a stimulant for improving the suboptimal cell-matrix interaction of polymeric scaffolds for tissue engineering applications.

Inhibition of human breast cancer cell (MBA-MD-231) invasion by the Ea4-peptide of rainbow trout pro-IGF-I

It was shown previously that Ea4‐peptide of trout pro‐IGF‐I exerted mitogenic activity in non‐transformed cells and inhibited colony formation in a soft agar medium of established human cancer cells. Here we report that the same peptide inhibits the invasion of human breast cancer cells (MDA‐MB‐231) through a matrigel membrane in a dose‐dependent manner. The expression of urokinase‐type plasminogen activator (uPA), tissue‐type plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI1) genes in MDA‐MB‐231 cells were downregulated by treatment with rtEa4‐peptide. The inhibition of expression of these genes in response to rtEa4‐peptide treatment was reduced to the control level when inhibitors for c‐Jun N‐terminal kinase 1/2 (JNK1/2), mitogen activated protein kinase kinase 1/2 (Mek1/2), p38 mitogen activated protein kinase (p38 MAPK), phosphatidylinositol 3‐kinase (PI3K), and phosphokinase C (PKC) were used. These results suggest that inhibition of invasion of MDA‐MB‐231 cells by rtEa4‐peptide may be mediated via the suppression of uPA, tPA, and PAI1 gene activities through signal transduction pathways. J. Cell. Biochem. 99: 1363–1373, 2006.

Fluorescent light mediated a green synthesis of silver nanoparticles using the protein extract of weaver ant larvae.

Alternative to crude plant extracts, a crude protein extract derived from animal cells is one of the potential sources of biomolecules for mediating a reduction of silver ions and a formation of silver nanoparticles (AgNPs) under a mild condition, which very few works have been reported. This work demonstrated a use of the protein extract of weaver ant larvae as a bio-facilitator for a simple, green synthesis of AgNPs under fluorescent light at room temperature. The protein extract of weaver ant larvae exhibited the reducing and antioxidant activities, which assisted a formation of AgNPs in the reaction containing only silver nitrate under light exposure. Transmission electron microscopy images revealed the dispersed, spherical AgNPs with an average size of 7.87±2.54nm. The maximum surface plasmon resonance (SPR) band of the synthesized AgNPs was at 435nm. The energy-dispersive X-ray analysis revealed that silver was a major element of the particles. The identity of AgNPs was confirmed by X-ray diffraction pattern, selected area electron diffraction and high resolution transmission electron microscopy analyses, which demonstrated the planes of face centered cubic silver. The synthesized AgNPs showed antibacterial activity against both Escherichia coli and Staphylococcus aureus with the minimum bactericidal concentration (MBC) values equally at 250μg/ml, suggesting their potential application as an effective antibacterial agent.

Biological activity of rainbow trout Ea4-peptide of the pro-insulin-like growth factor (pro-IGF)-I on promoting attachment of breast cancer cells (MDA-MB-231) via α2- and β1-integrin

E‐peptide of pro‐IGF‐I was considered as biologically inactive. We have demonstrated that rainbow trout (rt) Ea4‐peptide exerted biological activities in several established tumor cell lines [Chen et al., 2002 ; Kuo and Chen, 2002 ]. Here we report the activity of rtEa4‐peptide in promoting attachment of human breast cancer cells (MDA‐MB‐231). While rtEa2‐, rtEa3‐, and rtEa4‐peptides enhanced the attachment of MDA‐MB‐231 cells in a dose dependent manner, rtEa4‐peptide possessed the highest activity. Antibodies specific to α2 and β1 integrins significantly inhibited the attachment of cells to rtEa4‐peptide coated‐plates by 40%. In addition, rtEa4‐peptide induced the expression of fibronectin 1 and laminin receptor genes in MDA‐MB‐231 cells. Blocking new protein synthesis by cycloheximide significantly reduced the attachment of MDA‐MB‐231 cells to rtEa4‐peptide coated wells by 50%. These results suggest that rtEa4‐peptide may promote cell attachment by interacting with α2/β1 integrin receptors at the cell surface and by inducing the expression of fibronectin 1 and laminin receptor genes. Expression of fibronectin 1 gene induced by rtEa4‐peptide in MDA‐MB‐231 cells was abolished by inhibitors of PI3K, PKC, Mek1/2, JNK1/2, and p38 MAPK signaling transduction molecules. These results suggested that induction of fibronectin 1 gene expression in MDA‐MB‐231 cells by rtEa4‐peptide may be mediated via PI3K, PKC, Mek1/2, JNK1/2, and p38 MAPK signal transduction molecules. J. Cell. Biochem. 99: 1524–1535, 2006.

Egg extract of apple snail for eco-friendly synthesis of silver nanoparticles and their antibacterial activity

Abstract Green synthesis of silver nanoparticles (AgNPs) provides the alternative method with cost effectiveness and the eco-friendly process by using natural biomolecules as reducing and stabilizing agents. Alternative to the most studies of plant extracts, this work demonstrated a use of egg extract of apple snail (Pomacea canaliculata) for an eco-friendly production of AgNPs. The extract contained at least six proteins with the molecular weight in a range of 24–65 kDa that exhibited the reducing activity. The dispersive AgNPs were produced in the reaction containing only the extract and silver nitrate, as determined by the characteristic surface plasmon resonance peak of silver at 412 nm. The synthesized AgNPs were spherical with the average diameter of 9.0 ± 5.9 nm. The X-ray diffraction pattern and selected area electron diffraction (SAED) analyses confirmed the face-cubic centre (fcc) unit cell structure of AgNPs. The synthesized AgNPs exhibited the antibacterial activity against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Results of this work clearly showed the potential use of the egg extract of apple snail for a green synthesis of small size AgNPs exhibiting the antibacterial activity.