A protocol for synthesizing ~12 nm diameter gold nanoparticles (Au nanoparticles) in an organic solvent is presented. The gold nanoparticles are capped with oleylamine ligands to prevent agglomeration. The gold nanoparticles are soluble in organic solvents such as toluene.
Gold nanoparticles (Au nanoparticles) that are ~12 nm in diameter were synthesized by rapidly injecting a solution of 150 mg (0.15 mmol) of tetrachloroauric acid in 3.0 g (3.7 mmol, 3.6 mL) of oleylamine (technical grade) and 3.0 mL of toluene into a boiling solution of 5.1 g (6.4 mmol, 8.7 mL) of oleylamine in 147 mL of toluene. While boiling and mixing the reaction solution for 2 hours, the color of the reaction mixture changed from clear, to light yellow, to light pink, and then slowly to dark red. The heat was then turned off, and the solution was allowed to gradually cool down to room temperature for 1 hour. The gold nanoparticles were then collected and separated from the solution using a centrifuge and washed three times; by vortexing and dispersing the gold nanoparticles in 10 mL portions of toluene, and then precipitating the gold nanoparticles by adding 40 mL portions of methanol and spinning them in a centrifuge. The solution was then decanted to remove any remaining byproducts and unreacted starting materials. Drying the gold nanoparticles in a vacuum environment produced a solid black pellet; which could be stored for long periods of time (up to one year) for later use, and then redissolved in organic solvents such as toluene.
Gold nanoparticles are an interesting and useful class of nanomaterials that are the subject of many research studies and applications; such as biology1, medicine2, nanotechnology3, and electronic devices4. Scientific research on gold nanoparticles dates back to as early as 1857, when Michael Faraday performed foundational studies on the synthesis and properties of gold nanoparticles5. The two primary “bottom up” techniques for synthesizing gold nanoparticles are the citrate reduction method6,7,8 and the organic two-phase synthesis method9,10. The “Turkevich” citrate reduction method produces fairly monodisperse gold nanoparticles under 20 nm in diameter, but the polydispersity increases for gold nanoparticles above 20 nm in diameter; whereas the “Brust-Schiffrin” two-phase method uses sulfur/thiol ligand-stabilization to produce gold nanoparticles up to ~10 nm in diameter11. Gold nanoparticle solutions that are pre-synthesized using these methods are commercially available. For applications where large volumes, high monodispersity, and large diameters of gold nanoparticles are not necessary, it may be sufficient to purchase and use these pre-synthesized gold nanoparticles from suppliers. However, gold nanoparticles that are stored in solution, such as many of those that are commercially available, may degrade over time as nanoparticles begin to agglomerate and form clusters. Alternatively, for large-scale applications, long-term projects in which gold nanoparticles need to be used frequently or over a long period of time, or in which there are more stringent requirements for the monodispersity and size of the gold nanoparticles, it may be desirable to perform the gold nanoparticle synthesis oneself. By performing the gold nanoparticle synthesis process, one has the opportunity to potentially control various synthesis parameters such as the amount of gold nanoparticles that are produced, the diameter of the gold nanoparticles, the monodispersity of the gold nanoparticles, and the molecules used as the capping ligands. Furthermore, such gold nanoparticles can be stored as solid pellets in a dry environment, helping to preserve the gold nanoparticles so that they can be used at a later time, up to a year later, with minimal degradation in quality. There is also the potential for cost savings and the reduction of waste by fabricating gold nanoparticles in larger volumes and then storing them in a dry state so that they last longer. Overall, synthesizing gold nanoparticles oneself provides compelling advantages that may not be feasible with commercially available gold nanoparticles.
In order to realize the many advantages that are possible with gold nanoparticle synthesis, a process is presented herein for synthesizing gold nanoparticles. The gold nanoparticle synthesis process that is described is a modified version of a process that was developed by Hiramatsu and Osterloh12. Gold nanoparticles are typically synthesized with a diameter of ~12 nm using this synthesis process. The primary chemical reagents that are used to perform the gold nanoparticle synthesis process are tetrachloroauric acid (HAuCl4), oleylamine, and toluene. A nitrogen glovebox is used to provide an inert dry environment for the gold nanoparticle synthesis process, because tetrachloroauric acid is sensitive to water/humidity. The gold nanoparticles are encapsulated with oleylamine ligand molecules to prevent the gold nanoparticles from agglomerating in solution. At the end of the synthesis process, the gold nanoparticles are dried out in a vacuum environment so that they can be stored and preserved in a dry state for later use, up to one year later. When the gold nanoparticles are ready to be used, they can be resuspended into solution in organic solvents such as toluene.
Chemical Amounts:
NOTE: To obtain the appropriate chemical amounts for the nanoparticle synthesis, take the initial amounts found on the "Nanoparticle Synthesis" sheet (on the 2nd page of the supporting information from the Osterloh research article12), and multiply the amount of all doses by 3, with some slight modifications. Table 1 shows the chemical amounts that are needed for the injection solution, boiling solution, washing/purification solutions, and gold etchant solution.
Cleaning and Preparation for Gold Nanoparticle Synthesis Process (Day 1)
NOTE: The following steps can be completed on the first day of the synthesis process.
1. Things to Check and Ensure Before Preparing for the Gold Nanoparticle Synthesis
CAUTION: Ensure that the pre-synthesis cleaning and preparation are performed in the fume hood and acid wet bench while wearing personal protective equipment (PPE) such as nitrile gloves, safety glasses/goggles, and a lab coat while using the fume hood; and while additionally wearing chemical gloves, a chemical gown, a face shield, and goggles while using the acid wet bench.
2. Clean the Chemical Reaction Glassware (Before Gold Nanoparticle Synthesis)
CAUTION: Gold etchant TFA and aqua regia are corrosive. Wear the necessary personal protective equipment (PPE) such as chemical gloves, chemical gown, goggles, and face shield. Only handle the corrosive solution in an acid wet bench while wearing the necessary PPE.
3. Clean the Other Glassware and Synthesis Supplies
4. Transfer the Chemicals, Glassware and Supplies into the Nitrogen Glove Box
Gold Nanoparticle Synthesis Process (Day 2)
NOTE: The following steps can be completed on the second day of the synthesis process.
5. Set Up and Clean the Chemical Reaction Glassware & Supplies in the Nitrogen Glove Box
6. Toluene & Oleylamine Boiling Solution Preparation
CAUTION: Oleylamine is toxic and corrosive, so handle it carefully. If handling oleylamine outside the nitrogen glove box, wear the necessary personal protective equipment (PPE) such as chemical gloves, chemical gown, goggles, and face shield. If handling oleylamine inside the nitrogen glove box, make sure to cover the glove box gloves with new/clean XL nitrile gloves. Be careful to not accidentally spill the oleylamine. Some cleanroom wipes can be put down on the lab bench surface inside the glove box to help absorb any small spills.
7. Tetrachloroauric Acid, Oleylamine & Toluene Injection Solution Preparation
8. Injection of the Tetrachloroauric Acid, Oleylamine & Toluene Solution into the Vessel
9. Quenching the Reaction with Methanol After Cooling the Gold Nanoparticle Solution
10. Washing and Purifying the Gold Nanoparticles with Toluene and Methanol
NOTE: Each 50 mL centrifuge tube with gold nanoparticles will be washed and purified with 10 mL of toluene and 40 mL of methanol 3 times, cleaning the gold nanoparticles in batches of 6 centrifuge tubes at a time. The centrifuge tubes should have an equal amount of gold nanoparticle solution and should be equally weighted and balanced.
11. Drying the Gold Nanoparticles
NOTE: After the gold nanoparticles in the 50 mL centrifuge tubes have been washed 3 separate times, and the toluene and methanol has been poured out for the last time, the gold nanoparticles need to be dried to evaporate the remaining solvent. There are two ways to dry the gold nanoparticles and evaporate the solvent:
12. Clean the Chemical Reaction Glassware (After Gold Nanoparticle Synthesis)
CAUTION: Gold etchant TFA and aqua regia are corrosive. Wear the necessary personal protective equipment (PPE) such as chemical gloves, chemical gown, goggles, and face shield. Only handle the corrosive solution in an acid wet bench while wearing the necessary PPE.
Figure 1 shows how the gold nanoparticle synthesis chemical reaction mixture solution (tetrachloroauric acid, oleylamine, and toluene) should gradually change color over the course of several minutes as it initially boils in the reaction vessel; from clear, to light yellow (left image), to light pink (center image), to light red (right image). The changing color of the solution is an indication of the changing size of the gold nanoparticles as they begin to nucleate and grow larger over time. In general, the gold nanoparticle solution should become darker and more red/purple over time as the gold nanoparticles nucleate and grow. Figure 2 shows the final dark red/purple color of the gold nanoparticle synthesis chemical reaction mixture solution after 2 hours of boiling. The dark red/purple color of the gold nanoparticle solution is characteristic of a concentrated solution of gold nanoparticles that are ~12 nm in diameter. Figure 3 shows a scanning electron microscope (SEM) image of a gold nanoparticle monolayer (after being deposited onto a silicon substrate) which is used to characterize the size and monodispersity of the gold nanoparticles. The gold nanoparticles should all appear to have roughly the same size/diameter if they are highly monodisperse. If the gold nanoparticles are polydisperse, they will have large variations in their size/diameter. For most applications, monodispersity is usually preferred rather than polydispersity. Figure 4 shows a scanning electron microscope (SEM) image of gold nanoparticles and their diameter measurements, which indicates a diameter of ~12 nm ± 2 nm for the gold nanoparticles. These gold nanoparticles appear to be fairly monodisperse.
Solution Type | Item Number | Amount and Type of Chemical | Comments/Description |
Injection | 1 | 150 mg of tetrachloroauric acid (HAuCl4) (0.15 mmol) | for injecting into reaction vessel |
2 | 3.0 g (3.7 mmol, 3.6 mL) of oleylamine | ||
3 | 3.0 mL of toluene | ||
Boiling | 1 | 5.1 g (6.4 mmol, 8.7 mL) of oleylamine | for boiling in reaction vessel |
2 | 147 mL of toluene | ||
Washing/Purification | 1 | 10 mL of toluene (x3 washes) (x12 tubes) = 360 mL of toluene | for washing/purifying gold nanoparticles |
2 | 40 mL of methanol (x3 washes) (x12 tubes) = 1.44 L of methanol | ||
Gold Etchant | 1 | 150 mL of gold etchant TFA [or aqua regia] | for cleaning chemical reaction glassware/supplies |
2 | 150 mL of deionized (DI) water |
Table 1: Chemical Amounts This table shows the amount and type of chemicals that are needed for preparing the injection solution, boiling solution, washing/purification solution, and gold etchant solution.
Supplementary Figure 1: Cleaning Chemical Reaction Glassware with Gold Etchant TFA Solution. This figure shows the chemical reaction glassware (condenser tube, reaction vessel, glass pipette) and magnetic stir bar being cleaned with a ~300 mL mixture of ~150 mL of the gold etchant TFA solution and ~150 mL of DI water (1:1 mixture) in the condenser tube and reaction vessel glassware. The magnetic stir bar and long glass graduated pipette are placed into the condenser tube, and the gold etchant TFA bath is left to sit and clean the glassware for 30 minutes in the acid wet bench. Please click here to download this File.
Supplementary Figure 2: Clean Glassware and Supplies Before Being Transferred into Nitrogen Glove Box. This figure shows the glassware and supplies after being cleaned and dried. The glassware and supplies are wrapped/covered with aluminum foil to protect them from dirt/debris before they are transferred into the nitrogen glove box. Please click here to download this File.
Supplementary Figure 3: Gold Nanoparticle Synthesis Experimental Setup in Nitrogen Glove Box. This figure shows the gold nanoparticle synthesis experimental setup in the nitrogen glove box. The glass reaction vessel is resting on top of the fiberglass mesh receptacle on top of the heater/stirrer, and the condenser tube is connected on top of the glass reaction vessel. The condenser tube is mechanically supported by the stand with the clamp. There are two hoses connected to the water inlet and outlet ports of the condenser tube (with the inlet port on the bottom of the tube, and the outlet port on the top of the tube) so that water flows from the bottom of the condenser tube to the top of the condenser tube, cooling the tube off and condensing the vapor inside. Please click here to download this File.
Supplementary Figure 4: Mixing Tetrachloroauric Acid, Oleylamine, and Toluene Solution Before Injection. This figure shows the tetrachloroauric acid, oleylamine, and toluene injection solution after being mixed in a non-aqueous solution 20 mL glass vial with a PTFE-lined cap. The injection solution should look dark red or purple after shaking and mixing it. Please click here to download this File.
Supplementary Figure 5: Preparing to Inject Solution into Reaction Vessel Using Glass Pipette. This figure shows the tetrachloroauric acid, oleylamine, and toluene injection solution being drawn into the long graduated glass pipette with the rubber bulb with valves, just before quickly injecting the solution with one fast squirt into the boiling solution of oleylamine and toluene in the glass reaction vessel. Please click here to download this File.
Supplementary Figure 6: Pouring ~12 mL of Gold Nanoparticle Solution into Each 50 mL Conical Centrifuge Tube. This figure shows ~12 mL of gold nanoparticle solution being poured evenly into each of the 50 mL conical centrifuge tubes with ~35 mL of methanol in each tube. Methanol is used to remove unreacted starting materials and byproducts, in order to clean and wash the gold nanoparticles. Please click here to download this File.
Supplementary Figure 7: 50 mL Centrifuge Tubes after Centrifugation, with Gold Nanoparticle Pellets at the Bottom. This figure shows how the gold nanoparticle solution should appear in the 50 mL conical centrifuge tubes after centrifugation, with the gold nanoparticles collected into dark gold nanoparticle pellets at the bottom of each centrifuge tube. Above the dark gold nanoparticle pellets, the supernatant methanol/toluene solution appears to be clear/transparent, indicating that centrifugation has precipitated the gold nanoparticles from solution. Please click here to download this File.
Supplementary Figure 8: Vortexing 50 mL Centrifuge Tubes with Au NPs After Filling with ~10 mL of Toluene. This figure shows the centrifuge tubes with gold nanoparticle solution and toluene being vortexed and resuspended. Vortexing is much better and gentler on the gold nanoparticles than sonicating the gold nanoparticles. The gold nanoparticles should not be sonicated, as sonication could strip off the oleylamine ligands from the gold nanoparticles and cause aggregation and sedimentation of the gold nanoparticles. Please click here to download this File.
Supplementary Figure 9: Vortex Until Gold Nanoparticle Pellet/Residue is Almost Completely Resuspended. This figure shows how the gold nanoparticle solution should appear when the gold nanoparticles are resuspended into solution by vortexing each gold nanoparticle pellet with ~10 mL of toluene. The 50 mL centrifuge tubes should be vortexed until the black liquid/precipitate/gold nanoparticles are resuspended and dispersed in the toluene, and the solution looks cloudy/dark. The bottom of the centrifuge tube should be checked to ensure that virtually all or most of the black nanoparticle residue has been resuspended into solution. Please click here to download this File.
Supplementary Figure 10: Dried Gold Nanoparticle Pellet in 50 mL Conical Centrifuge Tube. This figure shows how a dried gold nanoparticle pellet at the bottom of a 50 mL conical centrifuge tube should look, after vacuum drying it. After the gold nanoparticles in the 50 mL centrifuge tube have been washed 3 separate times, and the toluene and methanol has been poured out for the last time, the gold nanoparticles need to be dried to evaporate the remaining solvent. Vacuum drying is the preferred method for drying because it is less likely to damage or lose the gold nanoparticle pellet, compared to more aggressive methods such as nitrogen gun drying. Please click here to download this File.
Supplementary Figure 11: Cap Tubes, Wrap with Laboratory Film, Label Tubes, and Store in 2 °C – 8 °C Fridge. This figure shows the centrifuge tubes capped, wrapped with laboratory film, labeled, and stored in a 2 °C – 8 °C fridge. The 50 mL centrifuge tubes with gold nanoparticle precipitate pellets should be labeled with an appropriately descriptive label, such as the name, sample number and date. A tray or 50 mL conical centrifuge tube racks can be used to hold the tubes upright in the fridge. Please click here to download this File.
Figure 1: Gold Nanoparticle Solution Changing Colors Over Several Minutes After Injection. This figure shows how the gold nanoparticle synthesis chemical reaction mixture solution (tetrachloroauric acid, oleylamine, and toluene) should gradually change color over the course of several minutes as it initially boils in the reaction vessel; from clear, to light yellow (left image), to light pink (center image), to light red (right image). The changing color of the solution is an indication of the changing size of the gold nanoparticles as they begin to nucleate and grow larger over time. Please click here to view a larger version of this figure.
Figure 2: Gold Nanoparticle Solution is Dark Red/Purple After 2 Hours of Boiling. This figure shows the final dark red/purple color of the gold nanoparticle synthesis chemical reaction mixture solution after 2 hours of boiling in the reaction vessel. The dark red/purple color of the gold nanoparticle solution is characteristic of a concentrated solution of gold nanoparticles that are ~12 nm in diameter. Please click here to view a larger version of this figure.
Figure 3: Scanning Electron Microscope (SEM) Image of Gold Nanoparticle Monolayer. This figure shows a scanning electron microscope (SEM) image of a gold nanoparticle monolayer (after being deposited onto a silicon substrate) which is used to characterize the size and monodispersity of the gold nanoparticles. Please click here to view a larger version of this figure.
Figure 4: Scanning Electron Microscope (SEM) Image with Gold Nanoparticle Diameter Measurements. This figure shows a scanning electron microscope (SEM) image of gold nanoparticles and their diameter measurements, which indicates a diameter of ~12 nm +/- 2 nm for the gold nanoparticles. Please click here to view a larger version of this figure.
Performing the gold nanoparticle synthesis protocol as presented above should produce gold nanoparticles with ~12 nm diameter and fairly high monodispersity (± 2 nm). However, there are some critical steps and process parameters that can be adjusted to potentially change the size/diameter and monodispersity/polydispersity of the gold nanoparticles. For example, after injecting the precursor solution into the reaction vessel and allowing the tetrachloroauric acid, oleylamine, and toluene solution to boil for two hours, there is an option to either do immediate quenching of the reaction solution or to do delayed quenching and natural cooling. If immediate quenching is desired, just after the 2-hour heated reaction step is complete, 100 mL of methanol is added to the reaction vessel to precipitate the gold nanoparticles product. Immediate quenching may provide better dispersion relationships because the nucleation occurs at roughly the same time for all nanoparticles in the saturated solution; whereas the longer the solution remains unquenched, the larger but more randomized the size of the nanoparticles become. If delayed quenching and natural cooling is instead desired, then after the 2-hour heated reaction step is complete, the solution is allowed to cool down naturally to room temperature for 1 hour. Alternatively, the solution could be left to cool even longer, until the following day (e.g., wait overnight) before 100 mL of methanol is added to precipitate the gold nanoparticles product. Researchers may want to experiment with both immediate quenching and delayed quenching, and 1 hour delayed quenching vs. overnight delayed quenching to determine which method produces the best results for making large and highly monodisperse gold nanoparticles. One hour delayed quenching is the procedure that is currently recommended to produce gold nanoparticles that are highly monodisperse, but it has not yet been determined which procedure yields superior results, so some further experimental investigations may be beneficial.
Another critical step in the protocol that affects the monodispersity of the gold nanoparticles is rapid injection of the precursor, to allow the saturated solution to form as many nuclei as possible over a very short time interval. Shortly after the precursor injection, few new nuclei form, and gold atoms should only join existing nuclei. What is necessary for high monodispersity is a long, consistent growth period relative to the nucleation period. A high growth:nucleation time ratio should benefit monodispersity. On this account, injecting the precursor solution very quickly is important for high monodispersity, and waiting to quench the reaction (delayed quenching) may also be beneficial for increasing the monodispersity. However, the competing mechanism of Ostwald ripening13 is a driving factor for polydispersity. The surface energy of gold atoms on the surface of small nanoparticles is higher than the surface energy of gold atoms on the surface of large nanoparticles. Ostwald ripening is a thermodynamic driving force for the shrinking of small nanoparticles and the growing of large ones14. This is a phenomenon that can happen over time in solution.
Another variable to consider is the stability of the oleylamine ligand layer on the gold nanoparticles, and how well passivated the gold nanoparticle surfaces are by the oleylamine ligands. Although there is no indicator for the progression of the surface passivation at different points in the gold nanoparticle synthesis reaction, one can imagine how the surface passivation must evolve over time. At the beginning of the reaction, there are no gold nanoparticles, and oleylamine is actually acting as a reducing agent, to free the gold from its chlorine bonds. At the end of the reaction, the gold nanoparticle surfaces should be completely passivated. Ideally, the reaction should be allowed to continue long enough to allow the surfaces of the gold nanoparticles to become completely passivated, but not so long that Ostwald ripening begins to make the gold nanoparticles polydisperse rather than monodisperse.
Overall, the things to consider when performing the quenching of the reaction are the growth:nucleation time ratio, minimizing Ostwald ripening time, and allowing sufficient time for surface passivation. It has not yet been proven whether delayed quenching or instantaneous quenching produces superior results (i.e., large, highly passivated, and highly monodisperse gold nanoparticles). However, slightly delayed quenching (e.g., allowing the solution to cool down to room temperature for 1 hour after boiling) can produce highly monodisperse gold nanoparticles, so some finite delay before quenching the reaction is acceptable. To provide more clarity as to whether immediate quenching or delayed quenching is better for producing large and highly monodisperse gold nanoparticles, a useful experiment or modification for troubleshooting of the technique would be to separate the gold nanoparticle synthesis solution into two different batches after boiling and perform the immediate post-reaction quenching in parallel with delayed quenching. The outcome of this experiment/modification may determine whether the nucleation time window is so short that the extra time (either one hour or one night/day later) for cooling is unneeded for growth, and some combination of Ostwald ripening and surface passivation is actually decreasing the monodispersity (or increasing the polydispersity) of the gold nanoparticles during the cooldown/delay before quenching.
The final consideration for this gold nanoparticle synthesis method is how the gold nanoparticles are stored and used. After the synthesis process and the cleaning process, the gold nanoparticles are dried gently, either using a nitrogen gun or under vacuum. It is highly recommended that the gold nanoparticles are dried in a vacuum environment rather than using a nitrogen gun, as the nitrogen gun could dislodge the black pellet of gold nanoparticles and cause it to become lost/contaminated/damaged. Drying the gold nanoparticles in a vacuum environment is much gentler and prevents the gold nanoparticle pellet from getting dislodged or lost. After drying, the gold nanoparticles are then stored in a clean and dry environment (e.g., in laboratory film-sealed capped conical centrifuge tubes) in a 2 °C – 8 °C refrigerator until they are ready to be used. This clean, dry, and cool environment should give the gold nanoparticles a longer shelf-life of approximately one year with minimal degradation. In order to use the gold nanoparticles, they may be resuspended into solutions of organic solvents such as toluene by vortexing the gold nanoparticles in the presence of the organic solvent. The size and concentration of the gold nanoparticles in the toluene solution can then be verified using UV-vis spectra characterization15 and diluted further with toluene if necessary until the desired concentration of gold nanoparticles is achieved. One limitation is that the concentration will need to be analyzed for each solution.
The gold nanoparticle synthesis protocol that is presented here is intended to enable the synthesis of gold nanoparticles by non-chemistry experts. The significance of this protocol with respect to existing methods is that it provides the opportunity to control the quantity of nanoparticles that are produced, the size of the nanoparticles, the monodispersity of the nanoparticles, and the ligands that encapsulate the gold nanoparticles. The gold nanoparticles that are synthesized using this process have been used to create nanoelectronic devices for molecular electronics experiments, such as 2D molecule-nanoparticle arrays16. In this example, 2D molecule-nanoparticle arrays are formed by depositing 200 µL of the diluted gold nanoparticles in toluene solution into 15 mL conical centrifuge tubes that were partially filled with deionized water. The tubes were left undisturbed for 1 – 3 hours to allow the toluene to evaporate and the gold nanoparticles to form monolayers on the surface of the water. These gold nanoparticle monolayers were then transferred to substrates such as silicon microchips using PDMS stamps, in order to form nanoelectronic devices. The oleylamine ligands on the gold nanoparticles were then exchanged with other molecules in order to change the electronic and thermoelectric properties of the gold nanoparticle-molecule monolayers17,18. The gold nanoparticle synthesis protocol that is presented here produces high-quality gold nanoparticles that may be useful for many other gold nanoparticle applications within science, industry, and medicine.
The authors have nothing to disclose.
The authors would like to thank Frank Osterloh for assistance with nanoparticle synthesis methods. The authors would like to acknowledge financial support from the National Science Foundation (1807555 & 203665) and the Semiconductor Research Corporation (2836).
50 mL Conical Centrifuge Tubes with Plastic Caps (Quantity: 12) | Ted Pella, Inc. | 12942 | used for cleaning/storing gold nanoparticle solution/precipitate (it's best to use 12 tubes, to allow the gold nanoparticles from the synthesis process to last up to one year (e.g., 1 tube per month)) |
Acetone | Sigma-Aldrich | 270725-2L | solvent for cleaning glassware/tubes |
Acid Wet Bench | N/A | N/A | for cleaning chemical reaction glassware/supplies with gold etchant solution (part of wet chemical lab facilities) |
Aluminum Foil | Reynolds | B08K3S7NG1 | for covering glassware after cleaning it to keep it clean |
Burette Clamps | Fisher Scientific | 05-769-20 | for holding the condenser tube and reaction vessel during the synthesis process (located in the nitrogen glove box) |
Centrifuge (with 50 mL Conical Centrifuge Tube Rotor/Adapter) | ELMI | CM-7S | for spinning the gold nanoparticles in solution and precipitating/collecting them at the bottom of the 50 mL conical centrifuge tubes |
DI Water | Millipore | Milli-Q Direct | deionized water |
Fume Hood | N/A | N/A | for cleaning laboratory glassware and supplies with solvents (part of wet chemical lab facilities) |
Glass Beaker (600 mL) | Ted Pella, Inc. | 17327 | for holding reaction vessel, condenser tube, glass pipette, and magnetic stir bar during cleaning with gold etchant and then with water |
Glass Beakers (400 mL) (Quantity: 2) | Ted Pella, Inc. | 17309 | for measuring toluene and gold etchant |
Glass Graduated Cylinder (5 mL) | Fisher Scientific | 08-550A | for measuring toluene and oleylamine for injection |
Glass Graduated Pipette (10 mL) | Fisher Scientific | 13-690-126 | used with the rubber bulb with valves to inject the gold nanoparticle precursor solution into the reaction vessel |
Gold Etchant TFA | Sigma-Aldrich | 651818-500ML | (with potassium iodide) for cleaning reaction vessel, condenser tube, magnetic stir bar, glass pipette [alternatively, use Aqua Regia] |
Isopropanol | Sigma-Aldrich | 34863-2L | solvent for cleaning glassware/tubes |
Liebig Condenser Tube (~500 mm) (24/40) | Fisher Scientific | 07-721C | condenser tube, attaches to glass reaction vessel |
Magnetic Stirring Bar | Fisher Scientific | 14-513-51 | for stirring reaction solution during the synthesis process |
Methanol (≥99.9%) | Sigma-Aldrich | 34860-2L-R | new, ≥99.9% purity (for washing gold nanoparticles after synthesis) |
Microbalance (mg resolution) | Accuris Instruments | W3200-120 | for weighing tetrachloroauric acid powder (located in the nitrogen glove box) |
Micropipette (1000 µL) | Fisher Scientific | FBE01000 | for measuring and dispensing liquid chemicals such as oleylamine and toluene (if using micropipette instead of graduated cylinder for measurement) |
Micropipette Tips (1000 µL) | USA Scientific | 1111-2831 | for measuring and dispensing liquid chemicals such as oleylamine and toluene (if using micropipette instead of graduated cylinder for measurement) |
Nitrile Gloves | Ted Pella, Inc. | 81853 | personal protective equipment (PPE), for protection, and for keeping nitrogren glove box gloves clean |
Nitrogen Glove Box | M. Braun | LABstar pro | for performing gold nanoparticle synthesis in a dry and inert environment |
Non-Aqueous 20 mL Glass Vials with PTFE-Lined Caps (Quantity: 2) | Fisher Scientific | 03-375-25 | for weighing tetrachloroauric acid powder and mixing with oleylamine and toluene to make injection solution |
Oleylamine (Technical Grade, 70%) | Sigma-Aldrich | O7805-100G | technical grade, 70%, preferably new, stored in the nitrogen glove box |
Parafilm M Sealing Film (2 in. x 250 ft) | Sigma-Aldrich | P7543 | for sealing the gold nanoparticles in the 50 mL centrifuge tubes after the synthesis process is over |
Round Bottom Flask (250 mL) (24/40) | Wilmad-LabGlass | LG-7291-234 | glass reaction vessel, attaches to condenser tube |
Rubber Bulb with Valves (Rubber Bulb-Type Safety Pipet Filler) | Fisher Scientific | 13-681-50 | used with the long graduated glass pipette to inject the gold nanoparticle precursor solution into the reaction vessel |
Rubber Hoses (PVC Tubes) (Quantity: 2) | Fisher Scientific | 14-169-7D | for connecting the condenser tube to water inlet/outlet ports |
Stainless Steel Spatula | Ted Pella, Inc. | 13590-1 | for scooping tetrachloroauric acid powder from small container |
Stand (Base with Rod) | Fisher Scientific | 12-000-102 | for holding the condenser tube and reaction vessel during the synthesis process (located in the nitrogen glove box) |
Stirring Heating Mantle (250 mL) | Fisher Scientific | NC1089133 | for holding and supporting reaction vessel sphere, while heating with magnetic stirrer rotating the magnetic stirrer bar |
Tetrachloroauric(III) Acid (HAuCl4) (≥99.9%) | Sigma-Aldrich | 520918-1G | preferably new or never opened, ≥99.9% purity, stored in fridge, then opened only in the nitrogen glove box, never exposed to air/water/humidity |
Texwipes / Kimwipes / Cleanroom Wipes | Texwipe | TX8939 | for miscellaneous cleaning and surface protection |
Toluene (≥99.8%) | Sigma-Aldrich | 244511-2L | new, anhydrous, ≥99.8% purity |
Tweezers | Ted Pella, Inc. | 5371-7TI | for poking small holes in aluminum foil, and for removing Parafilm |
Vortexer | Cole-Parmer | EW-04750-51 | for vortexing the gold nanoparticles in toluene in 50 mL conical centrifuge tubes to resuspend the gold nanoparticles into the toluene solution |