Synthesis Methods of Bimetallic Nanomaterials: Comparison
View Latest Version
Please note this is a comparison between Version 2 by Guiming Niu and Version 1 by Guiming Niu.

由两种不同金属元素组成的双金属纳米材料（Bimetallic nanomaterials (BMNs) are one kind of innovative nanomaterials, referring to nano-bimetallic alloy, intermetallic compounds, or the combination of two kinds of metallic nanoparticles. Compared with monometallic nanomaterials, BMNs perform similar or even better physical and chemical properties in the medical field. BMNs possess excellent physical and chemical properties, such as easy surface modification, superior photothermal properties, multiple catalytic properties, delicate sensitivity, and good stability. 

Synthesis methods of bimetallic nanomaterials. The preparation methods of BMNs commonly used for cancer therapy, s）具有一定的混合模式和几何结构，它们通常比单金属纳米材料具有优越的性能。双金属基纳米材料因其独特的形貌和结构、特殊的理化性质、优异的生物相容性和协同效应，在生物医学领域得到了广泛的研究和广泛的应用，特别是在癌症治疗领域。uch as co-reduction method, hydrothermal method, seed-mediated growth method, and electrodeposition method.

 

  • bimetallic nanomaterials
  • synthesis methods
  • physicochemical properties
  • application in tumor therapy

1. 简介Introduction

近年来，金属纳米材料（MNs）因其独特的光学性质、纳米尺寸效应和良好的生物相容性而在生物医学领域取得了令人瞩目的成就[1，2，3，4]。其中，MNs介导的纳米技术在肿瘤治疗方面的成就引起了很多关注，解决了传统癌症治疗中的副作用、创伤和不完全治疗，如光热疗法（PTT）[5，6]、光动力疗法（PDT）[7]、基因疗法（GT）[8]等。有趣的是，已经创建了传统合金以获得比单金属更好的稳定性和机械性能，以及当缩小到纳米级时。研究表明，与单金属纳米材料（MMNs）相比，双金属纳米材料（BMNs）具有相似甚至更好的物理和化学性能，其优异的光热和光催化性能以及类酶活性使其更适合肿瘤治疗[9]。因此，BMN在医疗领域引起了广泛的关注。
具有表面等离子体共振（SPR）效应的BMN由于其优异的光学特性而被用于癌症治疗。一个典型的例子是Pt纳米颗粒，一种良好的光热剂和酶样催化剂[10]，当与另一种催化金属纳米颗粒（NP）结合使用时，它具有级联催化活性和更有效的治疗效果[11，12]。如前人研究所示，与MMNs相比，BMNs在加热/冷却循环中具有良好的可重用性，可以通过调整形貌更准确地实现光热转换效率的调整，解决了PTTs与MMNs光热效率低的问题[13]。同时，BMNs由于其独特的理化性质，尤其是表面化学性质，具有更好的生物相容性、载药能力和放射增敏能力，为解决MMNs介导的癌症治疗的局限性提供了很大的帮助[14，15]。此外，如何实现BMNs在肿瘤治疗中的优势至关重要。

Generally, doping with the second metal is considered to possess superior performance than monometallic nanomaterials (MMNs), due to the addition of more active sites by the formation of metal polar bonds and irregular arrangement.[1][2] At the same time, the combination of the two metals is more likely to form complex structures with enhanced SPR effects such as hollow structures, porous structures, and core-shell structures.[3] Therefore, regulating the optical, electrical, chemical, and biological properties by controlling their size, shape, and composition during synthesis is particularly important in the study of monometallic nanomaterials (BMNs).[4] In order to achieve the design and effects, many methods have been extensively tested in the past decades. Among them, there is an important problem that the ratio of the two metals and the shape of BMNs are difficult to control.[5] BMNs with controlled composition can be synthesized by co-reduction method and hydrothermal method, and their shapes are mostly spherical and massive. BMNs synthesized by seed-mediated method usually perform complex shapes, while the BMNs obtained by electrodeposition are mostly nanowires and nanofilms. In order to obtain suitable BMNs for cancer therapy, a systematic understanding of the synthesis methods is required.

一般来说，与第二种金属的掺杂被认为比MMNs具有优越的性能，因为通过形成金属极性键和不规则排列增加了更多的活性位点[16，17]。同时，两种金属的组合更有可能形成具有增强SPR效应的复杂结构，例如中空结构，多孔结构和核壳结构[18]。因此，在合成过程中通过控制其大小、形状和组成来调节光学、电学、化学和生物学特性在BMN的研究中尤为重要[19]。为了达到设计和效果，在过去的几十年中，许多方法都经过了广泛的测试。其中，存在一个重要问题，即两种金属的比例和BMN的形状难以控制[20]。可采用共还原法和水热法合成成分受控的BMNs，其形状多为球形和块状。通过种子介导的方法合成的BMN通常具有复杂的形状，而通过电沉积获得的BMN大多是纳米线和纳米薄膜。为了获得适合癌症治疗的BMN，需要对合成方法有系统的了解。

2. BMN的合成方法Classification of synthetic methods

2.1. 协同还原法 Co-reduction method

Co-reduction is one of the most straightforward and convenient methods to prepare BMNs due to its simple operation, low cost, and short reaction time. Co-reduction, also known as the one-pot method, is usually used when two precursors containing metal elements are mixed, and the metal ions are reduced to form alloys or intermetallic compounds.[6][7] In addition, the BMNs’ morphology and structure can be tailored by the reaction temperature, the addition of surfactants, the reducing agent, and the nature of coordination ligand. Many common BMNs such as gold/silver core-shell structures, gold/silver nanowires, and gold/platinum NPs are synthesized by this method. More sophisticated nanomaterials with special shapes and structures can be synthesized by co-reduction in combination with other methods.[8] 

共还原是制备BMN最直接、最方便的方法之一，因为它操作简单、成本低、反应时间短。共还原法，也称为一锅法，通常在两种含有金属元素的前体混合，金属离子还原形成合金或金属间化合物时使用[24，25]。此外，BMN的形貌和结构可以通过反应温度，表面活性剂的添加，还原剂和配位配体的性质来定制。许多常见的BMN，如金/银核壳结构，金/银纳米线和金/铂NPs都是通过这种方法合成的。例如，聚乙烯吡咯烷酮-铂-铜纳米颗粒簇（PVP-PtCuNCs）是由Liu等人通过简便的方法开发的[26]。在他们的研究中，PVP-PtCuNCs从H2氯化铂6·6H2O 溶液和氯化铜4·5H2O溶液由抗坏血酸溶液再用PVP改性。合成的PVP-PtCuNCs表现出优异的多种酶模拟活性，如过氧化物酶（POD）样、过氧化氢酶（CAT）样和超氧化物歧化酶（SOD）样活性和高·哦-清除能力。 具有特殊形状和结构的更复杂的纳米材料可以通过共还原与其他方法相结合来合成。Joo等人使用共还原和模板辅助合成制备了嵌入Au纳米颗粒（AgCM / AuNPs）的单分散银立方体到网状纳米结构[27]。AgCM/AuNPs由6个具有相似纳米结构的等效面板组成，由于基于网状纳米结构的大表面积，具有很高的等离子体光催化剂。Takeuchi等人提出了电偶置换反应与共还原剂的组合，以合成具有空心颗粒壳结构的金核（Au@Ag@Pt core@multishell）上Ag-Pt双壳的金属NPs[28]。

2.2. 水热法Hydrothermal method

Hydrothermal method is another widely used method, which is similar to the co-reduction method. The metal precursors are promoted to decompose and reduce after heating. The hydrothermal method is generally applicable to reactions with lower reduction potentials that are not easily reduced directly. Up to date, some BMNs synthesized from metal precursors with lower reduction potentials have been prepared with this method, such as CuNi,[9][10] Ni-Fe,[11] CoNi,[12] and NiRe.[13] Besides, the hydrothermal method is not only suitable for metal precursors with low reducibility but also widely used in the synthesis of many BMNs (PtCu, PtPd, et al., for instance).[14][15] In a word, the hydrothermal method is simple to operate and easy to synthesize large quantities of BMNs.

另一种广泛使用的方法是水热法，它类似于共还原法。金属前驱体在加热后被促进分解和还原。水热法一般适用于还原电位较低、不易直接还原的反应。迄今为止，已经用这种方法制备了一些由还原电位较低的金属前驱体合成的BMN，例如CuNi [29，30]，Ni-Fe [31]，CoNi [32]和NiRe[33]。例如，Gai等人仅使用水合物、硝酸镍（II）九水合物和硝酸铁（III）九水合物设计和制备NiFe合金NPs。合成的NiFe NP具有可调节的形貌尺寸和催化性能。此外，水热法不仅适用于还原性低的金属前驱体，而且广泛用于合成许多BMN（例如PtCu，PtPd等）[34，35]。王和尹的小组研究了双金属CuAux（x = 0.01–0.04）NP催化剂[36]。铜金的NPx大约 13 和 5 nm。Liu等人通过简单的水热方法开发了一种双金属PdCu NP修饰的三维石墨烯水凝胶（PdCu / GE）[37]。总之，水热法操作简单，易于合成大量BMN。

2.3. Seed-mediated 种子介导的生长方法growth method

种子介导的生长已被证明是合成等离子体贵金属纳米晶体的有效方法[38]。该方法已应用于BMN的合成，因为制备的纳米晶体具有明确的形态，尺寸和表面组成。通常，种子介导的方法在制备各向异性金属结构和分层外延核/壳结构中起着重要作用[39，40，41，42]。Xia等人报道了在水溶液中合成Au@Ag核壳纳米立方体的简单途径[43]。首先，通过还原HAuCl合成非常小（2-3 nm）的Au纳米微晶4与纳布4在十六烷基三甲基溴化铵（CTAB）的溶液中。然后，HAuCl4、十六烷基三甲基氯化铵（CTAC）和L-抗坏血酸水溶液（AA）溶于超纯水中，然后加入3 nm Au NPs。混合物从无色变成红色，表明形成了更大的金种子。然后，将CTAC-Au种子和CTAC水溶液混合并在磁力搅拌下加热。最后，特定体积的AgNO水溶液3同时注入AA和CTAC的溶液和水溶液以形成Au@Ag纳米立方体。在这项工作中，可以精确调整银壳的厚度和Au@Ag的大小，该方法应该比其他方法更环保。 除了Au-Ag BMNs，这种方法也可以轻松合成其他一些具有高活性的新型金属BMN。Cargnello的小组开发了一种种子介导的方法来合成单分散Pt。x铜100-x具有受控Pt/Cu比率的纳米晶体合金[44]。他们证明了单个纳米晶体中的Pt和Cu以及Pt成功地合金化了x铜100-x具有受控的成分。种子介导生长法在合成BMNs领域因操作简单、重复性强、产量高而出现。特别是，BMN的形状和成分可以通过种子介导的方法精确调控，这是其他方法难以获得的。相信这种方法将来会得到更广泛的应用。

Seed-mediated growth has been proven an effective method for synthesizing plasmonic noble metal nanocrystals.[16] This method has been applied in the synthesis of BMNs because the prepared nanocrystals have well-defined morphology, size, and surface composition. Typically, seed-mediated methods play an important role in the preparation of anisotropic metal structures and hierarchical epitaxial core/shell structures.[17][18][19][20] Seed-mediated growth method has emerged in the field of synthesizing BMNs due to simple operation, strong repeatability, and high yield. In particular, the shapes and components of BMNs can be accurately regulated by the seed-mediated method, which is difficult to obtain by other methods. It is believed that this method will be more extensively used in the future.

2.4. Electrodeposition 电沉积法method

Electrodeposition is a simple and inexpensive synthesis method, which is widely used in the synthesis of nanotube, nanoporosity, and nanofilm [45,46,47].[21][22][23] For example, an innovative technology of striped gold–silver alloy nanowires (Au–Ag alloy NWs) was presented by Karn-orachai et al. [48]. In this work, the NWs were prepared by electrodeposition of Au–Ag alloy into the pores of etched ion-track membranes. The Au–Ag alloy NWs with a high surface-to-volume ratio is obtained by electrodeposition, which combines the advantages of porous Au and 1D nanostructure and has broad application prospects. In addition, Jia et al. synthesized Au-Pt nanostructures containing nanoporous Au and Pt nanoparticles by electrodeposition [49]. Briefls method is rarely, nanoporous Au (NPG) was first deposited on an electrode by dealloying of commercial alloy film, and then Pt nanoparticles were decorated on NPG by electrodeposition. In this work, the Au–Pt nanostructures were constructed to be a label-free immunosensor by directly immobilizing the antibody of NMP22 on the surface. Meanwhile, the BMNs showed electrocatalytic activity in the reduction of H2O2. The electrodepositiused to produce BMNs fon method also can synthesize other MNs. Downard et al. used copper foil as a carrier to form Cu and Au NPs by electrodeposition to modify graphene [50]. Th disease tre hierarchical nanostructure of various metals can also be synthesized by electrodeposition. Kim and coworkers presented a vertical growth of Ni-Cu-Se nanoflakes via the co-electrodeposition technique [51]. This method is rarely used to produce BMNs for disease treatmenttment, because of its limitations including harsh reaction conditions, low yield, and difficulty to control.

3. Application

BMNs exhibit various and complex morphologies based on spatial arrangements, which are related to abundant physicochemical properties. Common nanomaterials used in disease treatment are mainly manifested as nanospheres, nanorods, nanoclusters, nanostars, and nanoflowers, which have large surface areas and unique optical properties. BMNs with specific morphology and structure can be obtained by different synthesis methods for the treatment of tumor. 

In summary, many complex and diverse morphologies can be exhibited in BMNs that indicate the suitable characteristics for tumor therapy, such as good biocompatibility, drug-loading capacity, photothermal and catalytic properties. BMNs have a broad development prospect in tumor therapy by virtue of these abundant morphologies. BMNs have been widely used in biomedical fields, especially in biosensing and imaging, due to their unique catalytic and optical properties. In addition, many studies have shown that BMNs are also promising nanotechnology in cancer therapy.

4. Influence and new progress

In conclusion, the co-reduction method, hydrothermal method, and seed-mediated method have been widely used for the preparation of BMNs suitable for cancer therapy. Especially the seed-mediated method can precisely control the morphology of BMNs to obtain unparalleled properties. Although precise porous BMNs can also be obtained by the electrodeposition method and seed-mediated method, which are difficult to be obtained by other methods. It is exciting that BMNs with delicate structures can be synthesized more conveniently with the assistance of two synthesis methods, such as seed-mediated method and co-reduction [52], template synthesis and co-reduction [27].[24] Therefore, it is very important to choose the appropriate method according to the properties and morphology of BMNs.

However, it is still challenging to find suitable synthetic methods from many methods that can be used to produce BMNs for cancer therapy. It has been found that BMNs with zero dimension, such as spheres, rods, stars, and flowers, are usually used in cancer treatment. These structures are usually synthesized by seed-mediated and hydrothermal methods, where the regulation of BMNs' morphology has been well studied. In addition, we suggest that the growth pattern and mechanisms of all BMNs can be thoroughly explored by molecular simulation to establish a material library so that nanostructures with specific properties and shapes can be designed more clearly to reply to complex environments and various therapeutic applications.

References

  1. Sytwu, K.; Vadai, M.; Dionne, J.A. Bimetallic nanostructures: combining plasmonic and catalytic metals for photocatalysis. Adv. Phys.-X 2019, 4, 1619480. He, J.H.; Ichinose, I.; Kunitake, T.; Nakao, A.; Shiraishi, Y.; Toshima, N. Facile fabrication of Ag-Pd bimetallic nanoparticles in ultrathin TiO2-gel films: nanoparticle morphology and catalytic activity. J. Am. Chem. Soc. 2003, 125, 11034-11040.
  2. He, J.H.; Ichinose, I.; Kunitake, T.; Nakao, A.; Shiraishi, Y.; Toshima, N. Facile fabrication of Ag-Pd bimetallic nanoparticles in ultrathin TiO2-gel films: nanoparticle morphology and catalytic activity. J. Am. Chem. Soc. 2003, 125, 11034-11040.
  3. Zhang, H.; Jin, M.S.; Xia, Y.N. Enhancing the catalytic and electrocatalytic properties of Pt-based catalysts by forming bimetallic nanocrystals with Pd. Chem. Soc. Rev. 2012, 41, 8035-8049.
  4. Somu, P.; Paul, S. Protein assisted one pot controlled synthesis of monodispersed and multifunctional colloidal silver‑gold alloy nanoparticles. J. Mol. Liq. 2019, 291, 111303.
  5. Scaria, J.; Nidheesh, P.V.; Kumar, M.S. Synthesis and applications of various bimetallic nanomaterials in water and wastewater treatment. J. Environ. Manage. 2020, 259, 110011.
  6. Chiu, T.H.; Liao, J.H.; Gam, F.; Wu, Y.Y.; Wang, X.P.; Kahlal, S.; Saillard, J.Y.; Liu, C.W. Hydride-containing eight-electron Pt/Ag superatoms: structure, bonding, and multi-nmr studies. J. Am. Chem. Soc. 2022, 144, 10599-10607.
  7. Hu, Y.; Zhang, A.Q.; Li, H.J.; Qian, D.J.; Chen, M. Synthesis, study, and discrete dipole approximation simulation of Ag-Au bimetallic nanostructures. Nanoscale Res. Lett. 2016, 11, 1701751.
  8. Joo, J.H.; Kim, B.H.; Lee, J.S. Synthesis of gold nanoparticle-embedded silver cubic mesh nanostructures using AgCl nanocubes for plasmonic photocatalysis. Small 2017, 13, 1701751.
  9. Radwan, A.B.; Paramparambath, S.; Cabibihan, J.J.; Al-Ali, A.K.; Kasak, P.; Shakoor, R.A.; Malik, R.A.; Mansour, S.A.; Sadasivuni, K.K. Superior non-invasive glucose sensor using bimetallic CuNi nanospecies coated mesoporous carbon. Biosensors-Basel 2021, 11, 463.
  10. Motlak, M.; Barakat, N.; El-Deen, A.G.; Hamza, A.M.; Obaid, M.; Yang, O.B.; Akhtar, M.S.; Khalil, K.A. NiCu bimetallic nanoparticle-decorated graphene as novel and cost-effective counter electrode for dye-sensitized solar cells and electrocatalyst for methanol oxidation. Appl. Catal. A-Gen. 2015, 501, 41-47.
  11. Gai, C.; Zhang, F.; Yang, T.X.; Liu, Z.G.; Jiao, W.T.; Peng, N.N.; Liu, T.T.; Lang, Q.Q.; Xia, Y. Hydrochar supported bimetallic Ni-Fe nanocatalysts with tailored composition, size and shape for improved biomass steam reforming performance. Green Chem. 2018, 20, 2788-2800.
  12. Wei, L.G.; Chen, W.; Jia, C.Y.; Wang, D.; Li, M.; Dong, Y.L.; Song, W.N.; Liu, L.L.; Yang, Y.L. Facile synthesis of CoNi bimetallic nanoparticle decorated reduced graphene oxide as efficient and low-cost counter electrode for dye-sensitized solar cells. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2019, 19, 7790-7798.
  13. Wei, Z.J.; Cheng, Y.R.; Chen, M.T.; Ye, Y.H.; Liu, Y.X. Design of low-loaded nire bimetallic catalyst on N-doped mesoporous carbon for highly selective deoxygenation of oleic acid to n-heptadecane. Korean J. Chem. Eng. 2022, 39, 1753-1761.
  14. Xu, B.; Zhang, Z.C.; Wang, X. Formamide: an efficient solvent to synthesize water-soluble and sub-ten-nanometer nanocrystals. Nanoscale 2013, 5, 4495-4505.
  15. Habibi, A.H.; Hayes, R.E.; Semagina, N. Evaluation of hydrothermal stability of encapsulated PdPt@SiO2 catalyst for lean CH4 combustion. Appl. Catal. A-Gen. 2018, 556, 129-136.
  16. Feng, J.; Xu, D.D.; Yang, F.; Chen, J.X.; Wu, C.; Yin, Y.D. Surface engineering and controlled ripening for seed-mediated growth of Au islands on Au nanocrystals. Angew. Chem.-Int. Edit. 2021, 60, 16958-16964.
  17. Scala, A.; Neri, G.; Micale, N.; Cordaro, M.; Piperno, A. State of the art on green route synthesis of gold/silver bimetallic nanoparticles. Molecules 2022, 27, 1134.
  18. Orouji, A.; Abbasi-Moayed, S.; Ghasemi, F.; Hormozi-Nezhad, M.R. A wide-range pH indicator based on colorimetric patterns of gold@silver nanorods. Sens. Actuator B-Chem. 2022, 358, 131479.
  19. Zhang, Q.F.; Jing, H.; Li, G.G.; Lin, Y.; Blom, D.A.; Wang, H. Intertwining roles of silver ions, surfactants, and reducing agents in gold nanorod overgrowth: pathway switch between silver underpotential deposition and gold-silver codeposition. Chem. Mat. 2016, 28, 2728-2741.
  20. Xue, C.; Millstone, J.E.; Li, S.Y.; Mirkin, C.A. Plasmon-driven synthesis of triangular core-shell nanoprisms from gold seeds. Angew. Chem.-Int. Edit. 2007, 46, 8436-8439.
  21. Wang, D.; Wu, Z.; Li, F.X.; Gan, X.P.; Tao, J.M.; Yi, J.H.; Liu, Y.C. A combination of enhanced mechanical and electromagnetic shielding properties of carbon nanotubes reinforced Cu-Ni composite foams. Nanomaterials 2021, 11, 1772.
  22. Simunkova, H.; Lednicky, T.; Whitehead, A.H.; Kalina, L.; Simunek, P.; Hubalek, J. Tantalum-based nanotube arrays via porous-alumina-assisted electrodeposition from ionic liquid: formation and electrical characterization. Appl. Surf. Sci. 2021, 548, 149264.
  23. Katarkar, A.S.; Pingale, A.D.; Belgamwar, S.U.; Bhaumik, S. Experimental study of pool boiling enhancement using a two-step electrodeposited Cu-GNPs nanocomposite porous surface with R-134a. J. Heat Transf.-Trans. Asme 2021, 143, 121601.
  24. Wang, C.Y.; Chen, D.P.; Sang, X.H.; Unocic, R.R.; Skrabalak, S.E. Size-dependent disorder-order transformation in the synthesis of monodisperse intermetallic PdCu nanocatalysts. Acs Nano 2016, 10, 6345-6353.
More
© Text is available under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)
Video Production Service
Feedback