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Carboxymethylation of dextran for surface modification of magnetite nanoparticles.

机译：葡聚糖的羧甲基化用于磁铁矿纳米粒子的表面改性。

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Magnetite nanoparticles are currently studied for biomedical applications such as MRI, drug delivery, and magnetic fluid hyperthermia (MHF). These applications require nanoparticles with a suitable coating which provides colloidal stability and improves the nanoparticle's transport and interaction with biological tissues. Polysaccharides such as dextran have been used for this purpose due to their biocompatibility, low toxicity, and versatility for nanoparticle suspension in cell culture media. Functionalization of magnetite nanoparticles with dextran was performed by carbodiimide chemistry in which amine groups previously grafted onto the nanoparticle's surface are reacted with carboxylic groups (--COOH) present in the dextran chain. These --COOH groups were introduced in the dextran chains by a carboxymethylation reaction, obtaining a carboxymethyl-dextran molecule (CMDx). The amount of --COOH groups per chain was controlled by different parameters such as reaction time, temperature, and sodium hydroxide and monochloroacetic acid (ClCH2COOH) concentrations. CMDx with different degrees of substitution were prepared and the nanoparticle's surface charge and stability were studied using zeta potential measurements and dynamic light scattering. Results showed that decreasing the number of --COOH groups per dextran chain decrease the nanoparticle's surface charge without affecting their colloidal stability. The nanoparticles coated with CMDx with 5, 23 and 38 --COOH groups per dextran chain were stable over the entire range of pH and NaCl concentration studied.
机译：目前正在研究将磁铁矿纳米颗粒用于生物医学应用，例如MRI，药物输送和磁流体热疗（MHF）。这些应用需要具有合适涂层的纳米颗粒，该涂层提供胶体稳定性并改善纳米颗粒的运输以及与生物组织的相互作用。诸如右旋糖酐之类的多糖由于其生物相容性，低毒性和纳米粒子在细胞培养基中悬浮的多功能性而已用于该目的。用碳二亚胺化学法对磁铁矿纳米颗粒进行右旋糖酐官能化，其中先前接枝到纳米颗粒表面的胺基与右旋糖酐链中存在的羧基（-COOH）反应。通过羧甲基化反应将这些-COOH基团引入葡聚糖链中，从而获得羧甲基-葡聚糖分子（CMDx）。每条链上的--COOH基团的数量由不同的参数控制，例如反应时间，温度以及氢氧化钠和一氯乙酸（ClCH2COOH）的浓度。制备了不同取代度的CMDx，并使用zeta电势测量和动态光散射研究了纳米粒子的表面电荷和稳定性。结果表明，减少每条葡聚糖链上--COOH基团的数量会降低纳米颗粒的表面电荷，而不影响其胶体稳定性。在每个研究的pH和NaCl浓度的整个范围内，涂覆有CMDx的纳米颗粒每个葡聚糖链具有5、23和38个-COOH基团的纳米颗粒是稳定的。

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