The interaction between individual amino acids and the surface of carboxylate-modified polystyrene nanoparticles in solution was studied using Saturation-Transfer Difference (STD)–Nuclear Magnetic Resonance (NMR). Individual amino acids were screened for nanoparticle binding using an STD-NMR experiment at a fixed saturation time, and STD buildup curves were measured for those amino acids that exhibited significant STD difference signals in the initial screening. The strongest STD effects were measured for protons of aromatic side chains, with relatively weaker effects observed for protons in long-chain aliphatic and positively charged side chains. This indicates that there are several modes of binding to these polystyrene nanoparticles: electrostatic attraction between the negatively charged surface of the carboxylate-modified polystyrene nanoparticle and positively charged amino acids, hydrophobic effects between long aliphatic side chains and the nanoparticle surface, and π–π interactions between aromatic amino acids and aromatic groups in styrene. This information can be used in future studies to predict and understand interactions between nanoparticle surfaces and specific amino acid residues in small peptides and proteins.

中文翻译：

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使用饱和转移差（STD）-NMR探测与聚苯乙烯纳米颗粒表面的氨基酸相互作用

使用饱和转移差（STD）-核磁共振（NMR）研究了溶液中单个氨基酸与羧酸盐改性的聚苯乙烯纳米颗粒表面之间的相互作用。使用STD-NMR实验在固定的饱和时间筛选单个氨基酸的纳米粒子结合，并测量那些在初始筛选中显示出明显STD差异信号的氨基酸的STD积累曲线。对芳族侧链的质子测量出最强的STD效应，而在长链脂族和带正电的侧链中，观察到的质子效应相对较弱。这表明与这些聚苯乙烯纳米颗粒的结合方式有几种：羧酸盐修饰的聚苯乙烯纳米颗粒的带负电荷的表面与带正电荷的氨基酸之间的静电吸引，长脂肪族侧链与纳米颗粒表面之间的疏水作用以及苯乙烯中芳族氨基酸和芳族基团之间的π-π相互作用。该信息可用于将来的研究中，以预测和了解纳米粒子表面与小肽和蛋白质中特定氨基酸残基之间的相互作用。