Many in vivo and in vitro applications using gold nanoparticles (AuNPs) require (i) their PEGylation, as it increases their stability and prevents nonspecific protein adsorption, and (ii) their conjugation to biomolecules, that provides them with specific recognition properties. Currently, the functionalization of AuNPs is based on thiol chemistry that suffers from two major drawbacks: (i) the Au–S bond is labile and confers limited chemical robustness to the organic layer, and (ii) control over the bioconjugation density is highly challenging. We report here a novel functionalization strategy based on calix[4]arene-tetradiazonium platforms for the coating of AuNPs with a robust PEG layer and their controlled bioconjugation. AuNPs were first modified with a functional calix[4]arene-diazonium salt bearing three PEG chains ended by a methoxy group and one by a carboxyl group. The resulting particles showed excellent chemical and colloidal stabilities, compared to similar systems obtained via a classical thiol chemistry, and could even be dispersed in human serum without degrading or aggregating. In addition to that, the carboxyl groups protruding from the PEG layer allowed their conjugation via amide bond formation with amine-containing biomolecules such as peptides. The control of the bioconjugation was obtained by grafting mixed layers of functional and nonfunctional PEGylated calix[4]arenes, that allowed varying the number of functional groups carried by the AuNPs and subsequently their bioconjugation capacity while preserving their dense protective PEG shell. Finally, we used these nanomaterials, modified with peptide aptamers, for the in vitro biosensing of a cancer biomarker, Mdm2.

中文翻译：

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用于生物传感应用的具有可调生物共轭密度的超稳定聚乙二醇化杯芳烃涂层金纳米颗粒

许多体内和体外使用金纳米粒子 (AuNPs) 的应用需要 (i) 它们的聚乙二醇化，因为它增加了它们的稳定性并防止了非特异性蛋白质吸附，以及 (ii) 它们与生物分子的结合，为它们提供了特定的识别特性。目前，AuNPs 的功能化基于硫醇化学，其存在两个主要缺点：（i）Au-S 键不稳定，对有机层的化学稳定性有限，（ii）控制生物共轭密度极具挑战性. 我们在此报告了一种基于杯 [4] 芳烃-四重氮平台的新型功能化策略，用于用坚固的 PEG 层涂覆 AuNP 及其受控的生物共轭。AuNPs首先用功能性杯[4]芳烃-重氮盐修饰，该盐带有三个以甲氧基和一个以羧基结尾的PEG链。与通过经典硫醇化学获得的类似系统相比，所得颗粒显示出优异的化学和胶体稳定性，甚至可以分散在人血清中而不会降解或聚集。除此之外，从 PEG 层突出的羧基允许它们通过酰胺键与含胺的生物分子（如肽）形成共轭。通过接枝功能性和非功能性聚乙二醇化杯[4]芳烃的混合层来控制生物偶联，这允许改变 AuNP 携带的官能团数量和随后的生物偶联能力，同时保留其致密的保护性 PEG 壳。癌症生物标志物 Mdm2 的体外生物传感。