User:Keyun Wang/Notebook/Experimental Biological Chemistry I/2012/09/11

Experimental Biological Chemistry I

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Purpose Check if newly made sample on 2012/09/05 has reacted after 4 hours in the incubator at 85°C Measure UV absorbance on samples that were diluted in Tris buffer in different concentration and pH Procedure Two samples, one at 120 Au/BSA and another at 60 Au/BSA were made with stock solutions at concentrations used for 2012/09/04. The two samples were placed in incubator for an hour to check for possible reaction. UV absorbance were taken from samples that were mixed with Tris buffer from 2012/09/05. Sample at the ratio 134, 136, 138, 140, 160, 170 Au to BSA were centrifuged at 4000rpm, 7°C, for 5 minutes to ensure separation of supernatant and pallet. 500uL of each supernatant were used in each quartz cuvette. Each sample were run from 800nm to 200nm. The graph Absorbance versus Wavelength were plotted and shown in Melissa's Notebook. After an hour in the incubator, the 120 Au/BSA ratio solution turned to transparent, and the purple fibers formed in 60 Au/BSA ratio solutions. New sets of HAuCl4 and BSA solutions at different ratios were made with below amounts: HAuCl4/BSA ratio'' BSA[uL]'' HAuCl4[uL]'' H2O[mL]'' 60 165 32.2 3.803 80 165 43.0 3.792 100 165 53.7 3.781 120 165 64.5 3.771 128 165 68.7 3.766 130 165 69.8 3.765 132 165 70.9 3.764 133 165 71.4 3.764 134 165 72.0 3.763 136 165 73.0 3.762 138 165 74.1 3.761 140 165 75.2 3.760 160 165 85.9 3.749 170 165 91.3 3.744 Notes Sets of sample of Au/BSA with different ratios appeared gold in color after four hours in incubation. This indicates HAuCl4 has failed to react with BSA in solution. Au/BSA solutions mixed in tris buffer had a pellet at the bottom of the 50mL falcon tube, supernatent were carefully taken. For some samples the pellets were disturbed when transferring. To obtain pure supernatent, the falcon tubes were centrifuged. From the absorbance measurements, we concluded that all Au/BSA ratios worked successfully, results appeared identical to the results obtained from past experiments. All ratios for Au/BSA were concluded to be correct.