There has been little research on the dispersion of carbon nanotubes in dispersions of standard microbiological media. We report that tryptic soy broth (TSB) containing casein digest disperses single-walled carbon nanotubes (SWNT) at concentrations similar to those achieved in lysozyme (LSZ), one of the best known biomolecular SWNT dispersants. Similar to LSZ, the proposed mechanism for SWNT dispersion in TSB is favorable π–π stacking interactions with l-tryptophan. This is supported by similar SWNT concentrations in both LSZ and TSB supernatants, and the absence of appreciable dispersion in TSB that does not contain a source of l-tryptophan. Since l-tryptophan alone is insufficient to enable dispersion, it was previously hypothesized that LSZ’s macromolecular structure created steric hindrance that was critical for SWNT dispersion. These new results show that intermediately sized l-tryptophan containing species can also enable dispersion. In addition, since TSB is a commonly used growth medium for microbiological research, its dispersive ability presents new research avenues for studying the effect of SWNT on prokaryotic cells without the need to oxidize SWNT or add dispersants that may induce microbial stress.

中文翻译：

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胰蛋白酶大豆肉汤中的单壁碳纳米管分散体

关于碳纳米管在标准微生物介质分散体中的分散研究很少。我们报告含有酪蛋白消化物的胰蛋白酶大豆肉汤 (TSB) 分散单壁碳纳米管 (SWNT) 的浓度与溶菌酶 (LSZ) 中所达到的浓度相似，溶菌酶 (LSZ) 是最著名的生物分子 SWNT 分散剂之一。与 LSZ 类似，所提出的 SWNT 在 TSB 中分散的机制是有利的 π-π 堆积相互作用与l-色氨酸。这得到了 LSZ 和 TSB 上清液中相似的 SWNT 浓度的支持，并且在不含 L-色氨酸来源的TSB中不存在明显的分散。由于l-单独的色氨酸不足以实现分散，之前假设 LSZ 的大分子结构产生了对 SWNT 分散至关重要的空间位阻。这些新结果表明，中等大小的含有l-色氨酸的物质也可以分散。此外，由于 TSB 是微生物研究常用的生长培养基，其分散能力为研究 SWNT 对原核细胞的影响提供了新的研究途径，而无需氧化 SWNT 或添加可能诱导微生物应激的分散剂。