User:Monika Gasiorek/Notebook/CHEM-571 2014F/2014/09/16

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September 16, 2014 Stock Solution Preparation A 500 mL stock solution of 50 mM NaCl was made. 1.461 g of solid NaCl was dissolved in a 500 mL volumetric flask NOTE: The purpose of this solution was to serve as a dialyzing agent A 1 L stock buffer solution of 50 mM glycine with a pH of approx. 3.5 (pKa in glycine buffer range) was made. 3.7576 g of glycine was dissolved in a 1 L volumetric flask with the addition of 4.00 mL of 1 M HCl NOTE: The purpose of this solution was also to serve as a dialyzing agent. A buffer solution was necessary in order to change the ionic strength of the solution without altering its pH. Pure water results in the precipitation of the AuNP colloid; an acidic buffer solution is conducive to maintaining the desired structure in a desired pH range while allowing for changes in ionic strength/conductivity and the movement of ions across the dialysis tubing A 25 mL solution of 1 g/L lysozyme was made. 0.025 g of lysozyme was dissolved in 25.0 mL of water NOTE: The purpose of this solution was to serve as a baseline for the measurement of the equilibria/movement of free protein and/or ions across the dialysis tubing. A 10.0 mL sample of approximately 30:1 (rather 36.5:1) gold:protein colloid solution was obtained from previous experiments. The sample came from the addition of 1 mL of 70.96μm lysozyme and 1 mL of 2.53 mM gold, and 8 mL of water in day one of lab - not included in lab notebook. Dialysis 5 dialysis experiments were set up: I - 4.0 mL of the prepared lysozyme solution was dialyzed in about 3 in of 3500 g/mol MWCO tubing in a 150 mL beaker filled with approx. 120 mL of the 50 mM NaCl stock solution. II - 4.0 mL of the prepared lysozyme solution was dialyzed in about 3 in of 3500 g/mol MWCO tubing in a 150 mL beaker filled with approx. 120 mL of the 50 mM glycine stock solution. III - 4.0 mL of the prepared lysozyme solution was dialyzed in about 3 in of 3500 g/mol MWCO tubing in a 150 mL beaker filled with approx. 120 mL of pure water. IV - 4.0 mL of the prepared lysozyme solution was dialyzed in about 3 in of 25k g/mol MWCO tubing in a 150 mL beaker filled with approx. 120 mL of the 50 mM glycine stock solution. V - 4.0 mL of the 35.6:1 [Au]:[lys] solution wad dialyzed in about 3 in of 3500 g/mol MWCO tubing in a 150 mL beaker filled with approx. 120 mL of the 50 mM glycine stock solution. NOTE: A sixth dialysis using 15k g/mol MWCO tubing was intended (4.0 mL of lysozyme solution against 50 mM glycine soln), but the specific tubing was not available. Calibration Curves: pH and Conductivity pH and conductivity measurements were obtained for the baseline, as well as 4 serial dilutions (2x, 5x, 10x, 20x) of the 50 mM NaCl solution. Concentration (mM) pH Conductivity (μS/cm) 50 8.827 5.56 (mS/cm) 25 8.357 2924 10 8.199 1173 5 8.075 638 2.5 7.873 315 NOTE: To be continued...