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Developing an experimental design to investigate gold nanoparticle synthesis

  • Page ID
    241914
  • Purpose: The purpose of this exercise is to read literature describing the synthesis of gold nanoparticles using the citrate reduction method in order to identify experimental conditions that yield gold nanoparticles of different sizes.

    Learning Outcomes:

    At the end of this assignment you will be able to

    1. Adapt experimental procedures from scholarly articles pertaining to the synthesis of gold nanoparticles by the citrate reduction method.
    2. Understand how different experimental parameters affect gold nanoparticle size.

    Assignment:

    Q9. What are some experimental parameters you think may affect the growth of nanoparticles?

    There are a number of literature articles that describe how to synthesize gold nanoparticles.  The following articles may be a good start but many others are available:

    • Size Control of Gold Nanocrystals in Citrate Reduction: The Third Role of Citrate. Am. Chem. Soc. 2007, 129, 13939-13948.
    • Turkevich in New Robes: Key Questions Answered for the Most Common Gold Nanoparticle Synthesis. ACS Nano, 2015, 9 (7), pp 7052–7071.

    Read the literature and generate a list of experimental parameters that can be varied in the course of the reaction.

    Some variables that you may want to consider are:

    • Ratio of reactants
    • pH
    • Rate of citrate addition
    • Temperature
    • Stir rate

    In designing the experiment, remember it is best to change only one variable at any given time.  Let’s, for example, focus on ratio of reactants and pH.  You could design an experiment in which you vary the ratio of tetrachloroauric acid to citrate at a controlled pH value.  Or you could choose a set ratio of reagents and examine the effect that pH has on the products.

    A possible experimental grid is presented in Figure 4. This experiment would allow to explore nine possible combinations of reagent ratios and pH conditions.  Consult your instructor on the number of combinations to use.

    Initial pH

    Citrate to Auric Acid Ratio

     

    2.0:1

    4.0:1

    7.0:1

    4.2

     

     

     

    5.4

     

     

     

    7.0

     

     

     

    Figure 4. Example of experimental grid.

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