Ca^(2+)-亚氨二醋酸金属离子亲和色谱法吸附内毒素(英文)

Endotoxins(also known as lipopolysaccharides(LPS)) are undesirable by-products of recombinant proteins,purified from Escherichia coli.LPS can be considered stable under a wide range of temperature and pH,making their removal one of the most difficult tasks in downstream processes during protein purification.The inherent toxicity of LPS makes their removal an important step for the application of these proteins in several biological assays and for a safe parenteral administration.Immobilized metal affinity chromatography(IMAC) enables the affinity interactions between the metal ions(immobilized on the support through the chelating compound) and the target molecules,thus enabling high-efficiency separation of the target molecules from other components present in a mixture.Affinity chromatography is applied with Ca2+-iminodiacetic acid(IDA) to remove most of the LPS contaminants from the end product(more than90%).In this study,the adsorption of LPS on an IDA-Ca2+ was investigated.The adsorption Freundlich isotherm of LPS-IDA-Ca2+ provides a theoretical basis for LPS removal.It was found that LPS is bound mainly by interactions between the phosphate group in LPS and Ca2+ ligands on the beads.The factors such as pH(4.0 or 5.5) and ionic strength(1.0 mol/L) are essential to obtain effective removal of LPS for contaminant levels between endotoxin' concentration values less than100 EU/mL and 100 000 EU/mL.This new protocol represents a substantial advantage in time,effort,and production costs.

Nano-multilayered ZrN‒Ag/Mo‒S‒N film design for stable anti-frictional performance at a wide range of temperatures

A multilayer film,composed by ZrN‒Ag(20 nm)and Mo‒S‒N(10 nm)layers,combining the intrinsic lubricant characteristics of each layer was deposited using DC magnetron sputtering system,to promote lubrication in a wide-range of temperatures.The results showed that the ZrN‒Ag/Mo‒S‒N multilayer film exhibited a sharp interface between the different layers.A face-centered cubic(fcc)dual-phases of ZrN and Ag co-existed in the ZrN‒Ag layers,whilst the Mo‒S‒N layers displayed a mixture of hexagonal close-packed MoS_(2)(hcp-MoS_(2))nano-particles and an amorphous phase.The multilayer film exhibited excellent room temperature(RT)triblogical behavior,as compared to the individual monolayer film,due to the combination of a relative high hardness with the low friction properties of both layers.The reorientation of MoS_(2)parallel to the sliding direction also contributed to the enhanced anti-frictional performance at RT.At 400℃,the reorientation of MoS_(2)as well as the formation of MoO_(3)phase were responsible for the lubrication,whilst the hard t-ZrO_(2)phase promoted abrasion and,consequently,led to increasing wear rate.At 600℃,the Ag_(2)MoO_(4)double-metal oxide was the responsible for the low friction and wear-resistance;furthermore,the observed transformation from t-ZrO_(2)to m-ZrO_(2),could also have contributed to the better tribological performance.

Topical Calendula officinalis L.inhibits inflammatory pain through antioxidant,anti-inflammatory and peripheral opioid mechanisms

Objective The present study evaluated the antinociceptive activity of Calendula officinalis L.(Ca)cream on inflammatory hypernociception.Methods Creams with different Ca concentrations were tested for their ability to ameliorate pain-related behavior and edema in rats using formalin test,carrageenan(Cg)-induced acute inflammation model,bradykinin(BK)-induced acute inflammation model,and complete Freund’s adjuvant(CFA)-induced chronic inflammation model.Using the formalin test,we also examined the implication of peripheral opioid receptors in the antinociceptive mechanisms of Ca cream,by means of Q-naloxone,a peripherally acting nonselective opioid antagonist.Furthermore,the effects of Ca cream compared with diclofenac on BK-induced edema were examined when the kininase II in tissue was preserved or inhibited by captopril.The local production of redox biomarkers in formalin model,tumor necrosis factor-α(TNF-α)in Cg model and histopathological changes in CFA model were also evaluated.Results A single application of Ca cream at a dose of 10%or 30%(w/w)decreased the formalin-induced licking/biting behavior during both phases of this test in a Q-naloxone-sensitive manner.This effect was associated with the reduction of oxidative stress in the injured paw and the edema associated with the later phase of formalin-induced pain.A single application of Ca cream(10%or 30%)reduced paw edema and thermal hypernociception in Cg-induced acute inflammation,corresponding with a local decrease in TNF-α.Ca cream also inhibited BK-induced spontaneous nociceptive behavior and paw inflammation in both paradigms studied.Repeated applications of Ca cream also decreased CFA-induced chronic inflammation,mechanical hypernociception and histopathological changes in the paw.Conclusion These results reveal the topical antinociceptive and antiedematogenic effects of Ca cream.A modulatory action on peripheral opioid receptors associated with its antioxidant mechanism may be involved,at least in part,in its analgesic effects.These findings may have an impact on the clinical management of painful inflammatory diseases.