Nanocomposites comprising hydrogels and plasmonic nanoparticles are attractive materials for tissue engineering, bioimaging, and biosensing. These materials are usually fabricated by adding colloidal nanoparticles to the uncured polymer mixture and thus require time-consuming presynthesis, purification, and ligand-exchange steps. Herein, we introduce approaches for rapid synthesis of gold nanostars (AuNSt) in situ on hydrogel substrates, including those with complex three-dimensional (3D) features. These methods enable selective AuNSt growth at the surface of the substrate, and the growth conditions can be tuned to tailor the nanoparticle size and density (coverage). We additionally demonstrate proof-of-concept applications of these nanocomposites for SERS sensing and imaging. High surface coverage with AuNSt enabled 1–2 orders of magnitude higher SERS signals compared to plasmonic hydrogels loaded with premade colloids. Importantly, AuNSt can be prepared without the addition of any potentially cytotoxic surfactants, thereby ensuring a high biocompatibility. Overall, in situ growth becomes a versatile and straightforward approach for the fabrication of plasmonic biomaterials.

中文翻译：

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在 3D 水凝胶表面生长金纳米星


包含水凝胶和等离子体纳米粒子的纳米复合材料是组织工程、生物成像和生物传感的有吸引力的材料。这些材料通常是通过将胶体纳米粒子添加到未固化的聚合物混合物中来制造的，因此需要耗时的预合成、纯化和配体交换步骤。在此，我们介绍了在水凝胶基底（包括具有复杂三维（3D）特征的基底）上原位快速合成金纳米星（AuNSt）的方法。这些方法能够在基底表面选择性生长 AuNSt，并且可以调整生长条件以定制纳米颗粒尺寸和密度（覆盖率）。我们还展示了这些纳米复合材料在 SERS 传感和成像方面的概念验证应用。与负载预制胶体的等离子体水凝胶相比，AuNSt 的高表面覆盖率使 SERS 信号高出 1-2 个数量级。重要的是，AuNSt 的制备无需添加任何潜在的细胞毒性表面活性剂，从而确保了高生物相容性。总体而言，原位生长成为制造等离激元生物材料的一种通用且简单的方法。