User:Maria Briscione/Notebook/Chem 571/2011/08/31

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The purpose of the present subset of experiments was to monitor the change in concentration of AuNPs.


Bovine serum albumin (BSA, 0.0015-0.015 mM), a weak reducing agent, was mixed at room temperature with HAuCl4 (0.25-1mM) in aqueous phase. For 6 hours the mixture was maintained in a thermostat at 40, 60, or 80 °C. A color change of colorless to pink then purple was observed and indicative of the reduction. After 6 hours, the samples were first cooled, kept overnight, and purified twice to remove excess BSA. Specifically, AuNPs were collected at 10000-14000 rpms for 5 minutes after washing with distilled water.

UV spectrophotometer recorded UV- visible spectra of the prepared gold colloidal suspensions and a time dependent factor was determined by performing time dependent scans of choice reactions. Additionally, temperature monitoring over 20-70 °C range determined whether temperature was a significant factor. The pH of the samples was also determined. The various reaction solutions were contained in glass flasks that contained a double walled jacket. The temperature was maintained by use of externally circulating water while pH measurements were taken from a pH meter at regular increments for 6 hours.

The following procedure was taken from Bakshi and colleagues (2011) and utilized for use by the Biomaterial Design Lab to determine a proper pH to synthesize AuNPs.

10 mL of Au3+ (0.25 mM) and BSA (0.0015 mM) were added to 10 mL of 50 mM of Tris Buffer (pH 7.55). Small portions of distilled water were used to aid in mixing the solutions. A UV-vis spectrum was analyzed at 0 seconds (t0) and after every thirty minutes was completed. The samples were placed in an 80 degree Celsius oven while the reaction proceeded. A spectrum of a blank solution of pH buffer was also analyzed.

  • (.00084 g/mL) .0007 measured of chloroauric acid
  • (.001g/mL) .0013 measured of BSA


Uvis graphs 8 31.jpg


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