We report the development of molecularly imprinted polyacrylamide nanoparticles that bind to and neutralize the activity of cytotoxins present in the venom of the Mozambique Spitting Cobra (Naja mossambica mossambica). The binding activity of these nanoparticles is avid and specific. These findings hold promise for the development of a synthetic antivenom.
A chemical research program at a public high school has been developed. The full-year Advanced Chemical Research class (ACR) in the high school enrolls 20 to 30 seniors each year, engaging them in long-term experimental projects. Through partnerships involving university scientists, ACR high school students have had the opportunity to explore a number of highly sophisticated original research projects. As an example of the quality of experimental work made possible through these high school–university partnerships, this article describes the development of a novel method for the oxidation of ethidium bromide, a mutagen commonly used in molecular biology. Data collected from ACR alumni show that the ACR program is instrumental in encouraging students to pursue careers in scientific fields and in creating life-long problem-solvers.
Although many laboratory investigations and demonstrations use United States pennies (1-5), relatively little chemistry has been done with the penny's big brother, the "nickel". A United States 5-cent coin is made of an alloy that is 25% nickel and 75% copper (6). In this experiment, students isolate copper from a 5-cent coin using electrolysis (an example of the process of electrorefining). The isolation of pure copper metal from a coin that, at first glance, appears to be devoid of copper is a transformation that is both entertaining and highly educational for students ( Figure 1).
Electrolysis in a Chloride SolutionRefining of metals through electrolysis can be performed either through a process of selective oxidation or selective reduction (7). In this experiment, pure copper is obtained through a process of selective reduction. The 5-cent coin is used as the anode and a graphite rod is used as the cathode. 6 M HCl is used as the electrolyte. HCl is chosen as the electrolyte for two reasons: the acidity promotes the solubility of the transition metal ions produced during electrolysis, and the chloride ions form coordination complexes that also enhance the solubility of the transition metal ions. A schematic diagram of the experimental setup is shown in Figure 2.When electrolyzed in typical aqueous solutions, the metals that make up the 5-cent coin are oxidized according to the half-reactions:However, when a significant concentration of chloride ion is present in the electrolytic bath, the following oxidation halfreaction for copper is favored (8,9):CuCl is almost insoluble in water, but in a bath of 6 M HCl, the CuCl will react with additional Cl − ions to form soluble complexes such as CuCl 2 − and CuCl 3 2− (9). This solubility allows the copper ions to migrate through solution to eventually become reduced at the cathode.
Experimental ObservationsDuring the experiment, the 5-cent coin is gradually dissolved, resulting in an intensely green-colored electrolyte bath. The green color of the bath results from aqueous Ni 2+ ions (which may react with excess chloride ions to form complex ions such as NiCl 4 2− ). The copper(I) chloride complexes are nearly colorless, but may slowly (over a period of hours) be air oxidized to form green copper(II) chloride complexes (10).In a bath containing aqueous H + ions, Cu + complex ions, and Ni 2+ ions, the important reduction potentials are:CuCl + e − → Cu(s) + Cl − E Њ = +0.14 V 2H + + 2e − → H 2 (g) E Њ = +0.00 V Ni 2+ + 2e − → Ni(s) E Њ = ᎑0.25 V During the first few minutes of this electrolysis experiment, only hydrogen gas is formed at the cathode, but soon, as the
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