Bipyridinium salts, commonly known as viologens, are π-acceptor molecules that strongly interact with π-donor compounds, such as porphyrins or amino acids, leading their self-assembling. These properties have promoted us to functionalize polysilicon microparticles with bipyridinium salts for the encapsulation and release of π-donor compounds such as catecholamines and indolamines. In this work, the synthesis and characterization of four gemini-type amphiphilic bipyridinium salts (1·4PF₆–4·4PF₆), and their immobilization either non-covalently or covalently on polysilicon surfaces and microparticles have been achieved. More importantly, they act as hosts for the subsequent incorporation of π-donor neurotransmitters such as dopamine, serotonin, adrenaline or noradrenaline. Ultraviolet-visible absorption and fluorescence spectroscopies and high-performance liquid chromatography were used to detect the formation of the complex in solution. The immobilization of bipyridinium salts and neurotransmitter incorporation on polysilicon surfaces was corroborated by contact angle measurements. The reduction in the bipyridinium moiety and the subsequent release of the neurotransmitter was achieved using ascorbic acid, or Vitamin C, as a triggering agent. Quantification of neurotransmitter encapsulated and released from the microparticles was performed using high-performance liquid chromatography. The cytotoxicity and genotoxicity studies of the bipyridinium salt 1·4PF₆, which was selected for the non-covalent functionalization of the microparticles, demonstrated its low toxicity in the mouse fibroblast cell line (3T3/NIH), the human liver carcinoma cell line (HepG2) and the human epithelial colorectal adenocarcinoma cell line (Caco-2).

中文翻译：

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π-供体/π-受体相互作用在功能化的基于多晶硅的微粒上封装神经递质。

联吡啶鎓盐（通常称为紫精）是与卟啉或氨基酸等π供体化合物强烈相互作用的π受体分子，导致其自组装。这些性质促使我们用联吡啶鎓盐将多晶硅微粒功能化，以封装和释放诸如儿茶酚胺和吲哚胺的π供体化合物。在这项工作中，合成和表征了四种双子座型两亲联吡啶鎓盐（1·4PF ₆ – 4·4PF ₆），并将它们非共价或共价固定在多晶硅表面和微粒上。更重要的是，它们充当随后掺入诸如多巴胺，5-羟色胺，肾上腺素或去甲肾上腺素之类的π供体神经递质的宿主。紫外可见吸收和荧光光谱法以及高效液相色谱法用于检测溶液中络合物的形成。通过接触角测量证实了联吡啶鎓盐的固定化和在神经元表面掺入的神经递质。使用抗坏血酸或维生素C作为触发剂可实现联吡啶部分的减少以及随后神经递质的释放。使用高效液相色谱对从微粒中包裹和释放的神经递质进行定量。联吡啶鎓盐的细胞毒性和遗传毒性研究被选择用于微粒的非共价功能化的1·4PF ₆在小鼠成纤维细胞系（3T3 / NIH），人肝癌细胞系（HepG2）和人上皮结直肠腺癌细胞中显示出低毒性线（Caco-2）。