金纳米粒子合成
Summary
提出了在有机溶剂中合成直径约12纳米的金纳米粒子（Au纳米粒子）的协议。金纳米粒子用油胺脂蛋白封顶，以防止聚集。金纳米粒子可溶于甲苯等有机溶剂中。
Abstract
直径约12纳米的金纳米粒子（Au纳米粒子）通过在3.0克（3.7 mmol）中快速注入150毫克（0.15 mmol）的四氯酸溶液进行合成， 3.6 mL）的油胺（技术等级）和3.0 mL的甲苯在147 mL的甲苯中放入5.1克（6.4毫米醇，8.7毫升）的沸腾溶液中。在煮沸和混合反应溶液2小时时，反应混合物的颜色从透明变为浅黄色，变为浅粉色，然后慢慢变为深红色。然后关闭热量，并允许溶液逐渐冷却到室温1小时。然后，用离心机收集金纳米粒子并与溶液分离，洗三次：通过在10mL的甲苯部分旋转和分散金纳米粒子，然后通过加入40mL的甲醇部分并在离心机中旋转它们来沉淀金纳米粒子。然后，解决方案被拆除，以删除任何剩余的副产品和未经反应的起始材料。在真空环境中干燥金纳米粒子产生固体黑颗粒：可长期储存（最多一年）供以后使用，然后重新溶解在有机溶剂中，如甲苯。
Introduction
金纳米粒子是一种有趣而有用的纳米材料，是许多研究和应用的主题：如生物学1、医学2、纳米技术3和电子设备4。对金纳米粒子的科学研究可追溯到1857年，当时迈克尔·法拉第对金纳米粒子5的合成和特性进行了基础研究。合成金纳米粒子的两种主要”自下而上”技术是柠檬酸盐还原法6、7、8和有机双相合成法9、10。“Turkevich”柠檬酸盐还原法在直径在20纳米以下产生相当单分散的金纳米粒子，但直径在20纳米以上的金纳米粒子的多散率增加：而”布鲁斯特-希夫林”两相法使用硫/硫磺配体稳定生产直径达11纳米的金纳米粒子。使用这些方法预合成的金纳米粒子解决方案可在商业上获得。对于不需要大批量、高单分散度和大直径金纳米粒子的应用，从供应商那里购买和使用这些预合成的金纳米粒子可能就足够了。然而，储存在溶液中的金纳米粒子，如许多市售的纳米粒子，随着纳米粒子开始聚集并形成聚类，可能会随着时间的推移而降解。或者，对于大型应用，需要频繁或长期使用金纳米粒子的长期项目，或对金纳米粒子的单一性和尺寸有更严格的要求的项目，最好自己进行金纳米粒子合成。通过执行金纳米粒子合成过程，我们有机会控制各种合成参数，如所生产的金纳米粒子的数量、金纳米粒子的直径、金纳米粒子的单分性以及用作封盖配体的分子。此外，这种金纳米粒子可以作为固体颗粒储存在干燥的环境中，有助于保存金纳米粒子，以便它们可以在以后的时间，长达一年后，在质量上降解最小。此外，通过大量制造金纳米粒子，然后将其储存在干燥状态，使其持续更长时间，也有可能节省成本和减少浪费。总的来说，合成金纳米粒子本身提供了令人信服的优势，可能不可行与市售的金纳米粒子。
为了实现金纳米粒子合成的诸多优势，本文提出了金纳米粒子合成工艺。所描述的金纳米粒子合成过程是由平松和奥斯特洛12开发的过程的修改版本。黄金纳米粒子通常使用这种合成过程合成，直径约12纳米。用于执行金纳米粒子合成过程的主要化学试剂是四氯酸（HAuCl4）、油胺和甲苯。氮手套箱用于为金纳米粒子合成过程提供惰性干燥环境，因为四氯酸对水/湿度敏感。金纳米粒子用油胺脂蛋白分子封装，以防止金纳米粒子在溶液中聚集。在合成过程结束时，金纳米粒子在真空环境中干燥，以便它们可以储存和保存在干燥状态下供以后使用，最晚一年后使用。当金纳米粒子准备使用时，它们可以再注入溶液中的有机溶剂，如甲苯。
Protocol
化学量：注：为了获得纳米粒子合成的适当化学量，请将”纳米粒子合成”表（Osterloh 研究第12条支持信息的第 2 页）上的初始量乘以 3，并稍作修改。 表1 显示了注射液、沸腾溶液、洗涤/净化溶液和金等溶液所需的化学量。 金纳米粒子合成过程的清洁和准备（第1天）注：以下步骤可在合成过程的第一天完成。 <p…
Representative Results
图1显示金纳米粒子合成化学反应混合物溶液（四氯酸、油胺和甲苯）在反应容器中最初沸腾时，应在几分钟内逐渐改变颜色：从透明到浅黄色（左图），到浅粉色（中心图像），到浅红色（右图）。溶液颜色的变化表明，随着金纳米粒子开始核化并随着时间的推移而变大，其大小也在不断变化。一般来说，随着金纳米粒子的核化和生长，金纳米粒子溶液应随着时间的推移变…
Discussion
执行上述的金纳米粒子合成协议应产生直径约 12 nm 且单极性相当高（± 2 nm）的金纳米粒子。然而，有一些关键的步骤和过程参数，可以调整，以潜在地改变金纳米粒子的大小/直径和单分散/多散。例如，将前体溶液注入反应容器并允许四氯酸、油胺和甲苯溶液煮沸两小时后，可以选择立即淬火反应溶液或延迟淬火和自然冷却。如果需要立即淬火，在2小时加热反应步骤完成后，在反应容器中加入10…
Declarações
The authors have nothing to disclose.
Acknowledgements
作者要感谢弗兰克·奥斯特洛对纳米粒子合成方法的帮助。作者希望感谢国家科学基金会（1807555和203665）和半导体研究公司（2836）的财政支持。
Materials
| 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 |
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Citar este artigo
Marrs, J., Ghomian, T., Domulevicz, L., McCold, C., Hihath, J. Gold Nanoparticle Synthesis. J. Vis. Exp. (173), e62176, doi:10.3791/62176 (2021).