In vitro corrosion behavior and cytotoxicity property of magnesium matrix composite with chitosan coating

Mg-6%Zn-10%β-Ca3(PO4)2 composite was prepared through powder metallurgy methods with different chitosan coatings on its surface. The properties of the chitosan coatings on the surface of Mg-6%Zn-10%β-Ca3(PO4)2 composite, such as the adhesion ability, the corrosion behavior and the cytotoxicity properties, were investigated, and the microstructure of the chitosan coating was observed by scanning electron microscope(SEM). The results show that chitosan coating improves the corrosion resistance of the magnesium composite specimens significantly. Mg-6%Zn-10%β-Ca3(PO4)2 composite specimens exhibit good corrosion resistance and low p H values in simulated body fluid(SBF) at 37 °C in the immersion test with 7-layer chitosan coating whose relative molecular mass is 30×104 Da. The cytotoxicity tests indicate that Mg-6%Zn-10%β-Ca3(PO4)2 with chitosan coating is nontoxic with a cytotoxicity grade of zero against L-929 cells, which is better than that of uncoated composites.

Impact of scandium and terbium on the mechanical properties,corrosion behavior,and biocompatibility of biodegradable Mg-Zn-Zr-Mn alloys

Magnesium(Mg)-based bone implants degrade rapidly in the physiological environment of the human body which affects their structural integrity and biocompatibility before adequate bone repair.Rare earth elements(REEs)have demonstrated their effectiveness in tailoring the corrosion and mechanical behavior of Mg alloys.This study methodically investigated the impacts of scandium(Sc)and terbium(Tb)in tailoring the corrosion resistance,mechanical properties,and biocompatibility of Mg–0.5Zn–0.35Zr–0.15Mn(MZZM)alloys fabricated via casting and hot extrusion.Results indicate that addition of Sc and Tb improved the strength of MZZM alloys via grain size reduction and solid solution strengthening mechanisms.The extruded MZZM–(1–2)Sc–(1–2)Tb(wt.%)alloys exhibit compressive strengths within the range of 336–405 MPa,surpassing the minimum required strength of 200 MPa for bone implants by a significant margin.Potentiodynamic polarization tests revealed low corrosion rates of as–cast MZZM(0.25 mm/y),MZZM–2Tb(0.45 mm/y),MZZM–1Sc–1Tb(0.18 mm/y),and MZZM–1Sc–2Tb(0.64 mm/y),and extruded MZZM(0.17 mm/y),MZZM–1Sc(0.15 mm/y),MZZM-2Sc(0.45 mm/y),MZZM-1Tb(0.17 mm/y),MZZM-2Tb(0.10 mm/y),MZZM–1Sc-1Tb(0.14 mm/y),MZZM-1Sc-2Tb(0.40 mm/y),and MZZM–2Sc–2Tb(0.51 mm/y)alloys,which were found lower compared to corrosion rate of high-purity Mg(~1.0 mm/y)reported in the literature.Furthermore,addition of Sc,or Tb,or Sc and Tb to MZZM alloys did not adversely affect the viability of SaOS2 cells,but enhanced their initial cell attachment,proliferation,and spreading shown via polygonal shapes and filipodia.This study emphasizes the benefits of incorporating Sc and Tb elements in MZZM alloys,as they effectively enhance corrosion resistance,mechanical properties,and biocompatibility simultaneously.

Graphene nanoplatelets-reinforced magnesium metal matrix nanocomposites with superior mechanical and corrosion performance for biomedical applications

Magnesium(Mg)metal matrix composites(MMCs)reinforced with graphene nanoplatelets(GNPs)have been developed by powder metallurgy(PM).GNPs with different concentrations(0.1,0.2,and 0.3 wt.%),layer thicknesses(5 nm and 9 nm),and particle sizes(15μm and 5μm)were dispersed into Mg powder by high-energy ball-milling processes.The microstructure and mechanical properties of the fabricated composites were characterized using transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDX),X-ray diffraction(XRD),Raman spectroscopy(RS),and compression tests.The corrosion resistance was evaluated by electrochemical tests and hydrogen evolution measurements.The cytotoxicity of Mg-GNPs composites was assessed using osteoblast-like SaOS2 cells.The results indicate that GNPs are excellent candidates as reinforcements in Mg matrices for the manufacture of biodegradable Mg-based composite implants.GNP addition improved the mechanical properties of Mg via synergetic strengthening modes.Moreover,retaining the structural integrity of GNPs during processing improved the ductility,compressive strength,and corrosion resistance of the Mg-GNP composites.Cytotoxicity assessments did not reveal any significant toxicity with the addition of GNPs to Mg matrices.This study demonstrates that Mg-xGNPs with x<0.3 wt.%,may constitute novel biodegradable implant materials for load-bearing applications.

DNA Interaction and Cytotoxic Activity of a Chiral Amino-alcohol Schiff Base Derived Cu(Ⅱ) Complex

A novel copper（Ⅱ） complex based on chiral amino-alcohol derived Schiff base ligand,[Cu_4（R-L）_4（H_2O）_2]·（CH_3COOH）_2·（H_2O）（1,（R）-H_2 L =（R）-3-phenyl-2-（2-hydroxy-3-methoxybenzylideneamino） propane-1-ol）,was synthesized and characterized by EA,IR,UV-Vis,ESI-MS,circular dichroism spectra and single-crystal X-ray diffraction.Complex 1 crystallizes in orthorhombic,space group Ρ2_12_12 with a = 15.7660（14）,b = 49.526（3）,c = 10.4213（9） A,V = 8137.2（12） A^3,Ζ = 4,C_（72）H_（81）Cu_4N_4O_（19）,Mr = 1560.57,μ = 1.096 mm^-1,F（000） = 3244,Flack = 0.06（3）,the final R = 0.0924 and w R = 0.2451（I 〉 2σ（I）） for 41108 observed reflections.The interactions of the complex with calf thymus DNA（CT-DNA） were investigated by some spectroscopic technique methods.The results show the complex exhibits strong binding with CT-DNA.In addition,in vitro cytotoxicity test of 1 towards four kinds of human cancerous cell lines（He La,HL-60,Caco-2 and A549） showed substantial cytotoxic activity.The experimental investigations indicated that the chirality of complex 1 play an important role in cytotoxicity and interactions with DNA.

Therapeutic Activity of Partially Purified Fractions of Emblica officinalis （Syn, Phyllanthus embfica） Dried Fruits against Trypanosoma evansi

Emblica officinalis （E. oJficinalis） dried fruits were evaluated for its antitrypanosomal activity and cytotoxic effects. Vero cell line maintained in DMEM （Dubecco＇s Modified Eagle Medium） and incubated with Trypanosoma evansi for more than 12 h. MPE was added to the Vero cell culture medium at different concentrations （250-1,000 μg/mL） with trypanosomes concentration （1 × 106 trypanosomes/mL in each ELISA plate well） and incubated at appropriate conditions for 72 h. In-vitro cytotoxieity of MPE of E. officinalis was determined on Vero cells at concentrations （（1.56-100 ~tg/mL）. Acute toxicity and in-vivo infectivity tests were done in mice. Obtained MPE ofE. officinalis underwent process of purification via column chromatography, preparative chromatography and HPLC （higher performance liquid chromatography） with bioassay at different strata on Alsever＇s medium. In-vivo assay for trypanocidal activity, MPE and PPFs （partially purified fractions） of E. officinalis with two sets of mice, each mouse was inoculated with 1 × 104/mL oftrypanosomes and treated （48 h post inoculation） at concentrations （12.5, 25, 50, 100 and 200 mg/kg body weight） were administered at dose rate of 100 [tL per mouse via intraperitoneal route （in treating parassitemic mice） to different groups of mice, 6 mice per concentration. HPLC of partially purified fractions ofE. officinalis was carried out with mobile phase ofacetonitdle： water （40：60） in gradient mode. In vitro, MPE induced immobilization and killing of the parasites in concentration-time dependent manner. Significant reduction of trypanosomes counts from concentration of 250μg/mL and complete killing of trypanosomes at 5th hour of observation, which was statistically equivalent to 4th hour of Diminazine Aceturate （Berenil）, standard reference drug used. HPLC of the partially purified fractions revealed two major prominent peaks at retention time of 1-4 min. In vivo, both MPE and PPFs of test material did prolong lives of mice by 6-9 days but could not cure them. At concentration of 2,000 kg/kg body weight of MPE in acute test, all mice survived. For in-vivo infectivity test, mice injected with immobilized trypanosomes developed parasitemia and died while, the other group survived. MPE, PPFs and Diminazine Aceturate were toxic to Vero cells at all concentrations exception of 1.56, 1.56-3.13 and 1.56-6.25 μg/mL, respectively. From this report, PPFs ofE. officinalis dried fruits demonstrated potential pathway for a new development oftrypanocide in near future if additional investigations are put in place.

Preparation and Characterization of Paclitaxel/Chitosan Nanosuspensions for Drug Delivery System and Cytotoxicity Evaluation In Vitro

In this study,we prepared paclitaxel/chitosan(PTX/CS)nanosuspensions(NSs)with different mass ratios of PTX and CS(1.5:2,2:2,and 2.5:2),for controlled drug delivery purposes.For attachment and dispersion in water medium,a simple ultrasonic disruption technique was employed.The water-dispersed PTX/CS NSs exhibited a rod-shape morphology with an average diameter of 170-210 nm and average length of about 1-10μm.Transmission electron microscopy,differential scan-ning calorimetry and X-ray diffraction indicated that the obtained PTX/CS NSs contain a nanocrystalline PTX phase.It was also inferred that presence of CS can promotes the crystalline nature of PTX up to 80%.In addition,efficiency of PTX loading reached over 85%in freeze-dried PTX/CS NSs,showing a slow rate of drug release in vitro for 8 days.The MTT and LDH assessments revealed that PTX/CS NSs significantly inhibit the growth of tumor cells(HeLa),while it is slightly toxic for the normal cells(NIH/3T3).Therefore,PTX/CS NSs is suggested as a potential nanodrug delivery system for cancer therapy.

In vitro evaluation of inorganic and methyl mercury mediated cytotoxic effect on neural cells derived from different animal species

To extend the current understanding of the mercury-mediated cytotoxic effect,five neural cell lines established from different animal species were comparatively analyzed using three different endpoint bioassays：thiazolyl blue tetrazolium bromide,3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl tetrazolium bromide assay（MTT）,neutral red uptake assay（NRU）,and Coomassie blue assay（CB）.Following a 24-hr exposure to selected concentrations of mercury chloride（HgCl_2） and methylmercury（Ⅱ） chloride（MeHgCl）,the cytotoxic effect on test cells was characterized by comparing their 50%inhibition concentration（IC_（50）） values.Experimental results indicated that both these forms of mercury were toxic to all the neural cells,but at very different degrees.The IC_（50）values of MeHgCl among these cell lines ranged from 1.15±0.22 to 10.31 ± 0.70 μmol/L while the IC_（50） values for HgCl_2 were much higher,ranging from 6.44 ± 0.36 to 160.97±19.63 μmol/L,indicating the more toxic nature of MeHgCl.The IC_（50） ratio between HgCl_2and MeHgCl ranged from 1.75 to 96.0,which confirms that organic mercury is much more toxic to these neural cells than inorganic mercury.Among these cell lines,HGST-BR and TriG44 derived from marine sea turtles showed a significantly high tolerance to HgCl_2 as compared to the three mammalian neural cells.Among these neural cells,SK-N-SH represented the most sensitive cells to both chemical forms of mercury.

Synthesis and antimycobacterial screening of new N-(4-(5-aryl-3-(5-methyl-1,3,4-oxadiazol-2-yl)-1H-pyrazol-1-yl)phenyl)-4-amide derivatives

This article demonstrates the synthesis, characterization and the study of in vitro antitubercular activities of twenty four new N-（4-（5-aryl-3-（5-methyl-1,3,4-oxadiazol-2-yl）-1H-pyrazol-1-yl）phenyl）-4-amide derivatives（8a–x）. The antitubercular activity of the compounds against Mycobacterium tuberculosis H37Rv（MTB） revealed that 2-chloro-N-（4-（5-（4-chlorophenyl）-3-（5-methyl-1,3,4-oxadiazol-2-yl）-1H-pyrazol-1-yl）phenyl）benzamide（8n） is the most promising lead molecule with a MIC of1.56 mg/m L, while the corresponding unsubstituted benzamide derivative（8o） is the next most active molecule with a MIC of 3.13 mg/m L. Interestingly, the pyrazole intermediate 5b containing chlorophenyl and N-acylcarbohydrazide substituents also showed significant activity（MIC = 3.13 mg/m L）. Further, the active molecules did not show toxicity against a normal NIH 3T3 cell line, signifying their suitability for further drug development.