Gold Nanoparticle Synthesis

The objective of this gold nanoparticle synthesis process is to create gold nanoparticles that are about 12 nm.in diameter and are very monodisperse.This gold nanoparticle synthesis process is a modified version of a process described in the research article by Hiroki Hiramatsu and Frank E.Osterloh.Chemicals needed for synthesis and purification, tetrachloroauric acid, oleylamine, toluene and methanol.Begin setting up and cleaning the chemical reaction glassware and supplies in the nitrogen glove box.Ensure that the magnetic stir bar is inside the glass reaction vessel.Pour about 200 ml.of toluene into the glass reaction vessel.Place the glass reaction vessel with toluene onto the stirring heating mantle and deliver the condenser tube into the reaction vessel.Slowly turn on and monitor the water to ensure it is gently flowing into the condenser tube.Adjust the water flow as necessary by slightly opening or closing the water valve.Allow water to flow through the inlet port on the bottom of the condenser tube, up the condenser tube, and out the outlet port on top of the condenser tube.Continuously flow fresh nitrogen into the glove box to purge the glove box.Continuously ventilate the glove box by pulling a slight vacuum on the glove box.Start heating and stirring the toluene with a magnetic stirrer on the stirring and heating mantle.Allow the toluene to approach a gentle boil.Do not approach or exceed the flash points of toluene.Reduce the heat when it starts to boil.Allow the toluene to boil and evaporate for 30 minutes to clean the reaction glassware.The evaporated toluene will cool and condense in the condenser tube and drip back down into the reaction vessel.After 30 minutes, turn off the heater and allow the toluene to cool down for several minutes, until the toluene stops evaporating.After the toluene cools down, lift up the condenser tube and suspend it above the reaction vessel using the standard with clamps.Pour the toluene from the reaction vessel into the 400 ml.beaker.Be careful to not accidentally pour out the magnetic stir bar.Place the reaction vessel back on the heating and stirring mantle.Swirl the toluene around in the 400 ml.glass beaker to clean the beaker.Pour out the dirty/used toluene into the flammable waste bottle.Clean the beaker again with some fresh toluene and then, discard the used toluene into the vulnerable waste bottle.Make a boiling solution of 147 ml.or about 150 ml.of toluene at 8.7 ml, or about 9 ml.of oleylamine.Use the 400 ml.glass beaker to measure 147 ml.of toluene.Pour the 147 ml.of toluene from the glass beaker into the reaction vessel.Caution:Oleylamine is toxic and corrosive, so handle it with care.Do not spill the oleylamine Use the 5 ml.small glass graduated cylinder to carefully measure and pour 8.7 ml.of oleylamine.For example, first 4 ml.onto then 4.7 ml.Carefully pour the oleylamine from the glass graduated cylinder into the reaction vessel.Lower the glass condenser tube down into the glass reaction vessel again.Ensure that water is flowing through the outer chamber of the condenser tube to cool, condense, and collect the toluene and oleylamine vapor.Heat and stir the solution and allow the solution to approach a gentle boil.Begin preparing the injection solution:150 mg.of tetrachloroauric acid, 3.6 ml.of oleylamine, and a 3 ml.of toluene.Remove the laboratory film or a seal that is protecting the tetrachloroauric acid from air and moisture.The tetrachloroauric acid is very sensitive to water, moisture and humidity.Every effort should be made to prevent exposing the tetrachloroauric acid powder to air and water.The tetrachloroauric acid container should only be opened and stored in the nitrogen glove box.Use the metal spatula to deposit tetrachloroauric acid powder from the container into the glass vial on the microbalance, to a measured weight of 150 mg.of tetrachloroauric acid powder.Caution:Handle the oleylamine carefully as it is toxic and corrosive.Use the 5 ml.small glass graduated cylinder to measure 3.6 ml.of oleylamine.Carefully pour the 3.6 ml.of oleylamine from the 5 ml.small glass graduated cylinder into the 20 ml.glass vial without the tetrachloroauric acid.Carefully pour and measure 3 ml.of toluene into the 5 ml.small glass graduated cylinder.Carefully pour the 3 ml.of toluene from the 5 ml.small glass graduated cylinder into the 20 ml.glass vial with the oleylamine.Screw the PTFE-lined cap back onto the 20 ml.glass vial with the oleylamine and toluene inside.Shake and swirl the closed glass vial to mix the oleylammine and toluene solution together.Carefully pour the 150 mg.of tetrachloroauric acid powder into the glass vial with the oleylamine and toluene solution.Screw the PTFE-lined caps back onto the glass vials.Shake and swirl the closed glass vial with the tetrachloroauric acid, oleylamine and toluene to mix the solution together.Keep shaking the solution and ensure that it is mixed thoroughly.The tetrachloroauric acid, oleylamine and toluene solution should turn dark red.Ensure that water is slowly flowing into the bottom of the condenser tube and up out the top of the condenser tube.Adjust the water flow as necessary by carefully opening or closing the water valve.Ensure that the oleylamine and toluene solution in the reaction vessel is at a gentle boil, with some toluene and oleylamine evaporating into the condenser tube.Ensure that the magnetic stirrer is on.Raise the condenser tube above the reaction vessel using the stand with clamps to support the glassware.Make sure that you know how to operate the rubber bulb with valves and a glass pipe hats before using it.Press on the upper valve while squeezing the rubber bulb to deflate the rubber bulb.Carefully place the tip of the long graduated glass pipette into the 20 ml.glass vial with a tetrachloroauric acid, oleylamine, and toluene injection solution.Gently press the lower valve on the rubber bulb to slowly draw the tetrachloroauric acid, oleylamine, and toluene injection solution into the glass pipette.Carefully place the tip of the glass pipette into the opening of the reaction vessel and quickly inject the tetrachloroauric acid, oleylamine and toluene solution into the reaction vessel.The color should change from red to yellow to white within about a minute, as a gold nanoparticles begin to nucleate and grow.Lower the condenser tube back down into the reaction vessel.Heat the solution at a gentle boil for two hours.Over several minutes, the color should change from white to yellow to pink to red as the gold nanoparticles grow larger.After several minutes, the solution turns pink or light red.A couple of minutes later, the solution is even more red.The solution will continue to get darker red as it boils for two hours.After two hours of heating the solution, turn off the heater.Allow the gold nanoparticle solution to cool down naturally for one hour.Ensure that the heater has been turned off and the solution has cooled down.Stop flowing water through the condenser tube.Methanol will be used to clean the gold nanoparticles and remove the unreacted chemical reagent and byproducts.Pour 35 ml.of methanol into each of the 50 ml.conical centrifuge tubes.Then pour 12 ml.of gold nanoparticle solution into each of the 50 ml.conical centrifuge tubes with methanol.Be careful to not accidentally pour out the magnetic stir bar while pouring the gold nanoparticle solution into each centrifuge tube.After pouring 12 ml.of gold nanoparticle solution into each of the 50 ml.conical centrifuge tubes with 35 ml.of methanol, each centrifuge tube should have about 47 ml.of solution.Distribute any remaining gold nanoparticle solution evenly between the centrifuge tubes.Screw the caps onto the 50 ml.centrifuge tubes to close them and tighten the caps.Remove the 50 ml.conical centrifuge tubes with golden nanoparticle solution and a methanol from the nitrogen glove box.The centrifuge tube should have an equal amount of gold nanoparticle solution and should be equally weighted and balanced.Place six of the 50 ml.centrifuge tubes with gold nanoparticles into the centrifuge.Close the lid of the centrifuge and enter the settings for spinning the gold nanoparticles.RCF:1000.Timer:5 mins.Start spinning the centrifuge.After the first six centrifuge tubes with gold nanoparticles are done spinning, gently remove them from the centrifuge.Be careful to not disturb the gold nanoparticle pellets and place the tubes in the rack.The centrifugal force will pull down the gold nanoparticles in solution and separate them from the methanol and toluene.The gold nanoparticles will precipitate into pellets at the bottom of each centrifuge tube.Place the last six centrifuge tubes with gold nanoparticles into the centrifuge.Close the lid of a centrifuge and enter the settings for spinning the gold nanoparticles.RCF:1000.Timer:5 mins.Start spinning.After the centrifuge tubes are done spinning, gently remove them from the centrifuge and place them in the tube racks.Carefully carry all the centrifuge tubes over to the fume hood.Slowly and gently dump the solution from each centrifuge tube into the flammable waste to beaker.Be careful to not disturb and not pour out the gold nanoparticle pellets on the bottom of the tubes.The first methanol rinse cycle is now complete.Begin the second methanol rinse cycle by pouring 10 ml.of toluene into each centrifuge tube.Vortex each centrifuge tube to resuspend and disperse the gold nanoparticles throughout the 10 ml.toluene solution.Check the bottom of your centrifuge tube to ensure that the black residue has been resuspended.Pour 14 ml.of methanol into each centrifuge tube.With the 10 ml.of toluene already in each centrifuge tube, there will be 50 ml.of solution per tube.Screw the caps back onto their 50 ml.centrifuge tubes and ensure that the caps are on tight.Spin the centrifuge tubes in the centrifuge to collect the gold nanoparticles into a pellet at the bottom of each tube.Use the same centrifuge settings as before.Carefully pour out the methanol and toluene into the flammable waste to beaker like before.The second methanol rinse cycle is now complete.For the third and final rinse cycle, follow the same process as before for vortexing in toluene, cleaning in methanol, centrifugation and carefully pouring out the solvent.After pouring out the last toluene and the methanol rinse solution, the gold nanoparticles need to be dried.The recommended procedure is to vacuum dry the gold nanoparticles.Loosen the caps on the 50 ml.centrifuge tubes, so that the tubes are still covered, but solvent can evaporate and escape from inside the tubes.Place the rack of tubes with gold nanoparticles inside the vacuum load lock.Close and seal the outer load lock door and open the valve to the vacuum pump to start pulling vacuum on the load lock.Pump vacuum until a moderate vacuum pressure has reached, about the middle of the vacuum pressure gauge indicator.Leave the golden nanoparticles in the load lock at a moderate vacuum pressure about half gauge for a few minutes.Do not pump down to a lower pressure and do not leave in vacuum for too long, or the ligands may get detached.After the gold nanoparticles have been under vacuum for a few minutes to dry the gold nanoparticles and evaporate the remaining solvent, purge the load lock with nitrogen until the load loack reaches atmospheric pressure.Remove the 50 ml.centrifuge tubes with gold nanoparticles from the load lock, and inspect the dryness of the golden nanoparticles inside the fume hood.After the gold nanoparticle pellets are dry, screw the caps back onto the centrifuge tubes.Wrap laboratory film around the tightly closed caps to seal the centrifuge tubes with the golden nanoparticle pellets inside.Label the centrifuge tubes with gold nanoparticles and to place them inside a 2