Design and performance of an ultrahigh vacuum spectroscopic-imaging scanning tunneling microscope with a hybrid vibration isolation system.

A spectroscopic imaging-scanning tunneling microscope (SI-STM) allows for the atomic scale visualization of the surface electronic and magnetic structure of novel quantum materials with a high energy resolution. To achieve the optimal performance, a low vibration facility is required. Here, we describe the design and performance of an ultrahigh vacuum STM system supported by a hybrid vibration isolation system that consists of a pneumatic passive and a piezoelectric active vibration isolation stage. We present the detailed vibrational noise analysis of the hybrid vibration isolation system, which shows that the vibration level can be suppressed below 10-8 m/sec/√Hz for most frequencies up to 100 Hz. Combined with a rigid STM design, vibrational noise can be successfully removed from the tunneling current. We demonstrate the performance of our STM system by taking high resolution spectroscopic maps and topographic images on several quantum materials. Our results establish a new strategy to achieve an effective vibration isolation system for high-resolution STM and other scanning probe microscopies to investigate the nanoscale quantum phenomena.

Interplay between surface chemistry and osteogenic behaviour of sulphate substituted nano-hydroxyapatite.

Surface potential and chemical compositions of the bioceramics are the core of therapeutic effect and are key factors to trigger the interfacial interactions with surrounding hard and soft tissues to repair and regeneration. Ionic substitution in hydroxyapatite (Hap) lattice significantly influences the zeta potential from -16.46 ± 0.66 mV to -6.01 ± 0.68 mV as well as an average nano-rod length from ~40 nm to ~26 nm with respect to SO42- ion content. Moreover, the surface chemistry of Hap is mainly inter-related to SO42- substitution rate at PO42- site. Specifically, nano-sized feature with lowered negative surface potential influences the protein adsorption via their weak repulsive or attractive forces. Bovine serum albumin (BSA) and lysozyme (LSZ) adsorption studies confirmed the increased affinity to active binding sites of Hap's surface. Further, SO42- ion substituted Hap (SNHA) showed improved in vitro biomineralization activity and alkaline phosphatase activity. Expression of osteogenic biomarkers such as collagen I, V, osteopontin and osteocalcin were evaluated in Saos-2 and MC3T3-E1 cells. Gene expression of these markers was influenced by SO42- ion content in Hap (maximum with 10SNHA). Altogether, these data emphasizes that chemical composition and surface properties are dominant aspect in bioceramic development towards bone regeneration.

A novel nano-hydroxyapatite - PMMA hybrid scaffolds adopted by conjugated thermal induced phase separation (TIPS) and wet-chemical approach: Analysis of its mechanical and biological properties.

In this study, we report the preparation of nano-hydroxyapatite (nHAp) incorporated poly(methyl methacrylate) (PMMA) scaffolds by conjugated thermal induced phase separation (TIPS) and wet-chemical approach, which essentially facilitates the enhancement of both mechanical as well as biological properties of the scaffolds. The dissolution of PMMA was accomplished by acetone (Ace scaffold), ethanol-water (E-W scaffold) and isopropanol-water (I-W scaffold) mixtures as solvents. The existence of nHAp in PMMA matrix was investigated systematically. The higher degree of porous architecture was achieved from Ace scaffolds compared to both I-W and E-W scaffolds. On the other hand, the dense porous architecture of the I-W scaffold exhibited superior hardness and compressive strength than that of the Ace and E-W scaffolds. All the fabricated samples demonstrated enhanced in vitro bioactivity with respect to increasing immersion period as a result of flower-like in vitro apatite layer formation. The MTT assay was carried out for 1day and 3day culture using Saos-2 osteoblast-like cells, which showed better cell proliferation with increasing culture period owing to the interconnected pore architecture of scaffolds and the rational hemocompatibility as per the ASTM standard F756-00.

WITHDRAWN: A novel nano-hydroxyapatite - PMMA hybrid scaffolds adopted by conjugated thermal induced phase separation (TIPS) and wet-chemical approach: Analysis of its mechanical and biological properties.

The Publisher regrets that this article is an accidental duplication of an article that has already been published in Mater. Sci. Eng.: C, 73 (2017) 164­172, 10.1016/http://dx.doi.org/j.msec.2016.12.133. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Data on synthesis and characterization of chitosan nanoparticles for in vivo delivery of siRNA-Npr3: Targeting NPR-C expression in the heart.

This data article contains the data related to the research article 'Transient silencing of Npr3 gene expression improved the circulatory levels of atrial natriuretic peptides and attenuated ß-adrenoceptor activation-induced cardiac hypertrophic growth in experimental rats' (Venkatesan et al., 2016 [1]). The siRNA-Npr3 loaded chitosan nanoparticles were synthesized using ionotropic gelation method, where the positive charge of the chitosan interacts with the negative charge of STPP and siRNA-Npr3. The physicochemical properties of the synthesized siRNA-Npr3 loaded chitosan nanoparticles were studied by dynamic light scattering, FE-SEM and HR-TEM analysis. In addition, the loading efficiency and stability of the nanoparticles were also studied. Further, the gene silencing efficacy, hemocompatibility and biocompatibility were studied using Wistar rats (in vivo), isolated red blood cells and H9c2 cardiomyoblast cells, respectively.

Transient silencing of Npr3 gene expression improved the circulatory levels of atrial natriuretic peptides and attenuated ß-adrenoceptor activation- induced cardiac hypertrophic growth in experimental rats.

Natriuretic peptide receptor-C (NPR-C) is considered as a clearance receptor that maintains the circulatory levels of natriuretic peptides. It has been suggested that augmented expression of NPR-C as a cause for the diminished anti-hypertrophic action of natriuretic peptides in the failing heart. Hence, we sought to determine the level of Npr3 gene (coding for NPR-C) expression in the Isoproterenol (ISO) treated Wistar rats. In addition, we studied the effect of Npr3 gene silencing on the hypertrophic growth. A significant increase in heart weight-to-body weight ratio (HW/BW-24%,P<0.01), an indicator of cardiac hypertrophic growth was observed in the ISO (10mg/kg BW/day,i.p for 7 days) treated rats. As expected, the cardiac NPR-C protein expression was significantly increased by 4 fold as compared to control rats. In parallel, the circulatory atrial natriuretic peptide (ANP) level was significantly decreased (2 fold) in ISO treated rats. Upon treatment with siRNA-Npr3, a significant decrease in the cardiac NPR-C protein expression (70%,P<0.01), HW/BW ratio (70%,P<0.01) and hypertrophic marker genes (α-Sk, ß-MHC, c-fos, P<0.01, respectively) mRNA expression were observed. Interestingly, the circulatory ANP level was increased by 1.5 fold in the siRNA-Npr3 treated rats as compared to ISO treated rats. Moreover, the cardiac collagen content, matrixmetalloprotinases-2 (MMP-2) and enzymatic antioxidant status (P<0.01, respectively) were found to be restored back to near normal upon siRNA-Npr3 treatment. Taken together, the results of this study indicates that specific down-regulation of Npr3 gene improves the circulatory levels of ANP and antioxidant system and there by attenuates the ß-adrenoceptor over-activation mediated cardiac hypertrophic growth in experimental rats.

Evaluation of hemocompatibility and in vitro immersion on microwave-assisted hydroxyapatite-alumina nanocomposites.

This study reports the microwave-assisted synthesis and characterization of nHAp (nano-hydroxyapatite)-alumina composites. The crystalline phase and interaction of alumina with nHAp was analyzed using X-ray diffraction (XRD) and Raman microscopy analysis, respectively. High resolution transmission electron microscopy (HRTEM) micrographs exhibit morphological changes of nHAp composites with increasing alumina concentrations. Microhardness studies reveal the enhanced mechanical strength of nHAp10 and nHAp20 nanocomposites than pure nHAp. In vitro bioactivity of the nanocomposites was studied by immersing samples in simulated body fluid (Hank's solution) for 21 days. The surface of biomineralized samples were analyzed using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX). Hemolytic assay revealed acceptable compatibility for varying concentrations of all the samples. Cell proliferation assay was systematically investigated for 1 day and 3 days on Saos-2 osteoblast-like cell lines and it was found that nHAp nanocomposites improved the proliferation.

Rapid synthesis of biocompatible silver nanoparticles using aqueous extract of Rosa damascena petals and evaluation of their anticancer activity.

OBJECTIVE: To optimize the process parameters involved in the green synthesis of silver nanoparticles (G-SNPs) by aqueous extract of Rosa damascena petals and to evaluate the biocompatibility and anti cancer activity of the synthesized silver nanoparticles against human lung adenocarcinoma (A549). METHODS: The process variables that include concentration of extract, mixing ratio of reactants, silver salt concentration and interaction time were analyzed. The compatibility of the G-SNPs was verified by incubating with erythrocytes and the anticancer property of the G-SNPs against A549 cells was performed by MTT assay. RESULTS: Formation of G-SNPs was confirmed by the visual change in the colour of the reaction mixture from pale yellow to brown yellow. Surface plasmon resonance of synthesized G-SNPs was observed at 420 nm; the size of G-SNPs were analyzed by DLS and found to be in the range of (84.00±10.08) nm. Field emission scanning electron microscope and high resolution transmission electron microscopy analysis confirmed that the G-SNPs were fairly spherical. Fourier transform infrared spectroscopy spectroscopy and X-ray diffraction revealed the characteristic peaks of G-SNPs. Energy dispersive X-ray analysis showed a signal of silver around 3 keV. The synthesized G-SNPs exhibited anticancer activity as evidenced by the MTT assay. IC50 value of G-SNPs was found to be 80 µg/mL. CONCLUSION: The results of the present study suggest that G-SNPs can be synthesized rapidly within first minute of the reaction; they are biocompatible and possess anticancer activity against human lung adenocarcinoma.

Topical application of Gallic acid suppresses the 7,12-DMBA/Croton oil induced two-step skin carcinogenesis by modulating anti-oxidants and MMP-2/MMP-9 in Swiss albino mice.

Gallic acid (GA - 3,4,5-trihydroxybenzoic acid), a dietary anti-oxidant has been shown to inhibit cancer cell growth in in vitro. Herein, we investigated the in vivo chemo preventive activity of GA on 7,12-Dimethylbenz[a]anthracene (DMBA)/Croton oil induced two-step skin carcinogenesis in Swiss albino mice. Skin tumor incidence and tumor volume were recorded during the 16 weeks of experimental period. In addition, LDH-isozyme shift, skin collagen content, activities of matrix metalloproteinases (MMP-2/MMP-9) enzymes and enzymatic and non-enzymatic antioxidant were studied in the skin and serum of experimental mice. Tumor incidence was significantly increased in the DMBA/Croton oil induced mice (100%; p<0.001) when compared to GA co-treated mice (60%; p<0.01) and 5-FU treated mice (50%; p<0.01). Skin collagen content, MMPs activities, LDH-isoenzymes and MMP-2/-9 expressions were increased in DMBA/Croton oil induced skin while decreased levels of enzymatic (GST, SOD, CAT & GPx) and non-enzymatic anti-oxidant (GSH) were noticed. On the other hand, GA co-treatment exhibited a significant protection by reverting back the altered levels of LDH-isoenzymes, antioxidants, collagen and MMP-2/MMP-9 activities. The results of this study indicate that topical application of GA inhibits DMBA/Croton oil induced two-stage skin carcinogenic process by modulating the antioxidants and MMPs (-2 & -9) in the mouse skin.