Surface modification of nanoparticles involves numerous types of active molecules such as DNA, antibodies, enzymes, or carbohydrates. These modifications usually require reactive handles like amines, carboxylic acids, azides, etc. on the nanoparticles. In this work, utilizing poly-benzyl methacrylate based nanoparticles as a model nanoparticle system, the number of functional groups was tuned with functional comonomers, amino ethyl methacrylate for the amino groups or methyl methacrylate for the carboxylic groups. Herein a systematic study is presented where the functional groups in the nanoparticles are differentiated between total, visible and accessible functional groups. The concentration of each type of functional group is compared using various methods. Polymers synthesized using free radical polymerization were analyzed using ¹H-NMR spectroscopy to obtain the total number of functional groups. Via a miniemulsion–solvent evaporation technique, these polymers were used to synthesize the nanoparticles. Zeta potential, pH value and particle charge detection measurements were used to determine the number of visible functional groups. The number of accessible functional groups was quantified by conjugating small dyes and fluorescence measurements were directly executed on the system under investigation, hence eliminating errors associated with indirect measurements and detecting very low concentrations (e.g. 80 nM). Lastly, human serum albumin was conjugated to investigate the effect of a bulky molecule on the accessibility of these reactive handles.

中文翻译：

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在纳米颗粒表面定制反应性手柄，用于生物分子的共价偶联


纳米颗粒的表面改性涉及多种类型的活性分子，例如 DNA、抗体、酶或碳水化合物。这些修饰通常需要反应性处理，如胺、羧酸、叠氮化物等。在纳米颗粒上。在这项工作中，利用基于聚甲基丙烯酸苄酯的纳米颗粒作为模型纳米颗粒系统，用功能共聚单体、甲基丙烯酸氨基乙酯作为氨基或甲基丙烯酸甲酯作为羧基来调整官能团的数量。本文提出了一项系统的研究，其中纳米颗粒中的官能团分为总官能团、可见官能团和可访问官能团。使用各种方法比较每种官能团的浓度。使用 ¹H-NMR 波谱分析使用自由基聚合合成的聚合物，以获得官能团的总数。通过微乳液-溶剂蒸发技术，这些聚合物用于合成纳米颗粒。使用 Zeta 电位、pH 值和粒子电荷检测测量来确定可见官能团的数量。通过偶联小染料定量可接近的官能团数量，并直接在所研究的系统上进行荧光测量，从而消除了与间接测量相关的误差，并检测出非常低的浓度（例如 80 nM）。最后，偶联人血清白蛋白以研究大体积分子对这些反应性手柄可及性的影响。