A miniature tyrosinase-based electrochemical sensing platform for label-free detection of protein tyrosine kinase activity was developed in this study. The developed miniature sensing platform can detect the substrate peptides for tyrosine kinases, such as c-Src, Hck and Her2, in a low sample volume (1-2 μL). The developed sensing platform exhibited a high reproducibility for repetitive measurement with an RSD (relative standard deviation) of 6.6%. The developed sensing platform can detect the Hck and Her2 in a linear range of 1-200 U/mL with the detection limit of 1 U/mL. The sensing platform was also effective in assessing the specificity and efficacies of the inhibitors for protein tyrosine kinases. This is demonstrated by the detection of significant inhibition of Hck (~88.1%, but not Her2) by the Src inhibitor 1, an inhibitor for Src family kinases, as well as the significant inhibition of Her2 (~91%, but not Hck) by CP-724714 through the platform. These results suggest the potential of the developed miniature sensing platform as an effective tool for detecting different protein tyrosine kinase activity and for accessing the inhibitory effect of various inhibitors to these kinases.
In this paper, we report our attempt to elaborate on cellulose-based materials and their potential application in membrane science, especially in separation applications. Furthermore, the cellulosic membrane has received attention for potential use as biomaterials such as novel wound-dressings and hemodialysis materials. In this mini-review, we mainly focus on the separation and antimicrobial properties of cellulosic membranes and the advanced synthesis/processing methods for superior functional quality for various potential applications. Finally, we conclude with the market and the impact of developments of future expectations.
Multiple studies have examined the direct cellular toxicity of silver nanoparticles (AgNPs). However, the lung is a complex biological system with multiple cell types and a lipid-rich surface fluid; therefore, organ level responses may not depend on direct cellular toxicity. We hypothesized that interaction with the lung lining is a critical determinant of organ level responses. Here, we have examined the effects of low dose intratracheal instillation of AgNPs (0.05 μg/g body weight) 20 and 110 nm diameter in size, and functionalized with citrate or polyvinylpyrrolidone. Both size and functionalization were significant factors in particle aggregation and lipid interaction in vitro. One day post-intratracheal instillation lung function was assessed, and bronchoalveolar lavage (BAL) and lung tissue collected. There were no signs of overt inflammation. There was no change in surfactant protein-B content in the BAL but there was loss of surfactant protein-D with polyvinylpyrrolidone (PVP)-stabilized particles. Mechanical impedance data demonstrated a significant increase in pulmonary elastance as compared to control, greatest with 110 nm PVP-stabilized particles. Seven days post-instillation of PVP-stabilized particles increased BAL cell counts, and reduced lung function was observed. These changes resolved by 21 days. Hence, AgNP-mediated alterations in the lung lining and mechanical function resolve by 21 days. Larger particles and PVP stabilization produce the largest disruptions. These studies demonstrate that low dose AgNPs elicit deficits in both mechanical and innate immune defense function, suggesting that organ level toxicity should be considered.
Understanding the electrochemical stability or corrosion behavior of metallic nanoparticles in aqueous environments is of central importance in the fields of catalysis, sensing, nanoelectronics and photonics [1]. The advantages of nanoparticles, such as increased solubility of nanosuspensions and their low production costs have resulted in their rapid commercialisation for medical applications ( e.g . drug delivery) [2]. In addition, metal ion release is a major pathway underlying their potential toxicity, and the cellular environment can be considered as an electrochemical cell. Therefore, stability against oxidation or loss of effective surface area is necessary for metallic nanoparticles (NPs) to retain their useful properties in long-term applications and also important for understanding the safety of NPs. The objective of this study was to investigate the electrochemical stability of silver nanoparticles (AgNPs) as a function of applied potential, pH and particle size. AgNPs with controlled size and size distribution were deposited on to boron-doped diamond electrodes via magnetron sputtering, with size-filtering capability. The anodic behavior of AgNPs in perchlorate buffer pH solutions (ranging from pH 2-12) were examined by linear sweep voltammetry. The surface chemistry and oxidation state of Ag after each treatment were characterized using X-ray photoelectron spectroscopy (XPS). The size distribution of AgNPs in response to electrochemical polarization was examined using atomic force microscopy (AFM). Pourbaix diagrams for bulk Ag suggest that the equilibrium condition is not pH-dependent in acidic conditions. However, we observe that, for nanoparticles with the average size of 4.4 ± 2.1 nm, the oxidation potential deviates from expectation in acidic conditions by approximately 0.015V / pH . By contrast, the relationship between potential and pH follows that of bulk Ag for alkaline solutions. XPS confirmed the expected electrochemical changes in surface chemistry, with binding energy (BE) of Ag3d 5/2 photoelectron signal and O1s/C1s ratio correlating with the observed changes in the silver oxidation state. These direct voltammetric measurements of the Ag oxidation potential, as a function of size and pH, indicate the electrochemical stability of NPs is different from their bulk metal. This study supports the findings of Tang et.al ., [3] suggesting that theoretically derived energy diagrams for a bulk material might not always accurate to NPs, especially AgNPs which has been shown in our studies. References: [1] Y.G. Sun, Y.D. Yin, B.T.Mayers, T. Herricks & Y.N.Xia. (2002). Uniform Silver Nanowires Synthesis by Reducing AgNO3 with Ethylene Glycol in the presence of Seeds and Poly(Vinyl Pyrrolidone). Chem. Mater. 14 (11). pp 4736 – 4745. [2] P. Couvreur. (2013). Nanoparticles in Drug Develiry: Past, Present and Future. Adv. Drug Delivery Reviews. 65 . pp 21-23. [3] L.Tang, X.Q. Li, R.C. Cammarata, C. Friesen & K. Sieradzki. (2010). Electrochemical Stability of Elemental metal Nanoparticles. J. Am. Chem. Soc. 132 . pp 11722-11726.
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