Interfacial chemicals for metal surface functionalization were developed for applications of high water dispersibility and environmental stability. Metal nanomaterials, i.e., gold nanoparticles (AuNPs), were synthesized by introducing various interfacial chemicals, to improve the hydrophilicity of biosensors, such as those used in fluorescence resonance energy transfer (FRET) and lateral flow assay (LFA), respectively. Previously, thiolated AuNPs (SH-AuNPs) exhibited colloidal instability by forming irreversible aggregates in extreme environmental conditions; this phenomenon led to limitations such as poor sensitivity and reproducibility, in terms of biosensor application fields. Therefore, the development of novel interfacial chemicals remained a challenge for AuNP-based biosensor applications. Here, we first synthesized and demonstrated an ultra-stable AuNP functionalization by introducing N-heterocyclic carbene (NHC) compounds with a polyethylene glycol chain and azide terminal groups (NHC-AuNPs). The high binding energy of NHC-AuNPs compared with SH-AuNPs was demonstrated by density functional theory simulation, with NHC-AuNPs showing an unprecedented stability in extreme environmental conditions with varying ranges of pH, salts, and temperature; in particular, ultra-stability was observed in condition by freezing/thawing over 120 times. NHC-AuNPs were applied FRET and LFA biosensors and showed excellent sensing performances. Based on the results, NHC-AuNPs can be introduced for performance improvement in the development of diagnostic platforms to utilize in extreme environmental conditions.

中文翻译：

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基于N-杂环卡宾界面化合物的超稳定金纳米颗粒


用于金属表面功能化的界面化学品是针对高水分散性和环境稳定性的应用而开发的。通过引入各种界面化学物质合成金属纳米材料，即金纳米颗粒（AuNP），以提高生物传感器的亲水性，例如分别用于荧光共振能量转移（FRET）和侧流测定（LFA）的生物传感器。此前，硫醇化金纳米粒子（SH-AuNPs）在极端环境条件下形成不可逆的聚集体，表现出胶体不稳定性。这种现象导致了生物传感器应用领域的局限性，例如灵敏度差和重现性差。因此，新型界面化学品的开发仍然是基于金纳米粒子的生物传感器应用的一个挑战。在这里，我们首先通过引入具有聚乙二醇链和叠氮端基的N-杂环卡宾（NHC）化合物（NHC-AuNPs）来合成并展示了超稳定的AuNP功能化。通过密度泛函理论模拟证明了NHC-AuNPs与SH-AuNPs相比具有较高的结合能，NHC-AuNPs在不同pH、盐和温度范围的极端环境条件下表现出前所未有的稳定性；特别是在冷冻/解冻超过120次的条件下观察到超稳定性。 NHC-AuNPs应用于FRET和LFA生物传感器并表现出优异的传感性能。根据结果​​，可以引入 NHC-AuNP 以提高诊断平台开发的性能，以便在极端环境条件下使用。