The Effect of Silver Nanoparticle Solutions in Varying Molarities on the Growth of Escherichia coli

Gram-negative bacteria, such as Escherichia coli, have gained the ability to become highly resistant to conventional antibiotic treatment. Using silver nanoparticles is an alternative to antibiotics and can be created in different molarities. The purpose of this experiment was to determine what molarity solution of silver nanoparticles had the most success inhibiting the growth of Escherichia coli. A solution of silver nitrate (AgNO3) and a solution of sodium alginate [(C6H7O6)n] were mixed in specific amounts together to create the different molarities of silver nanoparticles: 1 millimolar (mM), 2 mM, and 3 mM. Then, these silver nanoparticle solutions were applied to the nutrient agar and a certain dilution of E. coli was applied to the agar one, two, and three times, and directly streaked from the bacteria slant. There were also positive and negative controls. The constant throughout the experiment were the temperature that the bacteria were grown in and the amount of silver nanoparticles that were added to the agar. After the experiment was conducted and the data was analyzed, it was concluded that the 3 mM silver nanoparticle solution was the most effective in inhibiting the growth of the E. coli. This was because the 3 mM solution had the highest amount of silver nitrate. Silver nitrate contains silver ions, and silver ions are quite effective in disrupting bacteria growth, ending in the death of the cell.

Research Conducted By:

Jacob Arche
Sterling Heights High School

Cathleen Saraza
Sterling Heights High School