Journal of Colloid and Interface Science ( IF 9.4 ) Pub Date : 2020-06-27 , DOI: 10.1016/j.jcis.2020.06.093 Surojit Ranoo 1 , B B Lahiri 1 , Manali Nandy 1 , John Philip 1
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Hypothesis
Magnetic fluid hyperthermia has attracted considerable attention for cancer therapeutics. Magnetic nanoemulsions are potential candidates for multi-modal hyperthermia due to the possibility of volumetric loading with suitable chemo/photo-therapy agents. Often, the nanocarriers are stabilized using organic molecules that behave differently under varying pH and hence, an understanding of their interfacial behaviour is important for practical applications.
Experiments
We probe the magnetic heating efficiency of poly acrylic acid (PAA) stabilized oil-in-water magnetic nanoemulsions, as a function of pH, where the conformational changes of the PAA molecules are studied using dynamic light scattering and inter-droplet force measurements.
Findings
A ~50% enhanced heating efficiency is observed when solution pH is reduced from ~9 to 3, which is attributed to the coil-to-globule conformational changes of the PAA molecules. The increased ionization of the carboxylic acid groups, at higher pH, leads to reduced hydrophobicity that results in an increase in the interfacial thermal resistance causing a lower magneto-thermal heating efficiency at higher pH. The proposed interfacial heat transfer hypothesis is experimentally verified using thermal imaging, where a lower rate of heat transfer is obtained at higher pH. The observed enhanced hyperthermia efficiency at low pH is beneficial for designing efficient pH-responsive nano-carriers for multi-modal hyperthermia.
中文翻译：
酸性pH值提高了用弱聚电解质稳定的磁性纳米乳剂的磁性加热效率。
假设
磁流体热疗已引起癌症治疗的广泛关注。磁性纳米乳液是多峰热疗的潜在候选者，因为可能会使用合适的化学/光疗剂进行容量加载。通常，使用在变化的pH下行为不同的有机分子来稳定纳米载体，因此，了解它们的界面行为对于实际应用很重要。
实验
我们探讨了聚丙烯酸（PAA）稳定的水包油磁性纳米乳剂的磁加热效率与pH的关系，其中使用动态光散射和液滴间力测量研究了PAA分子的构象变化。
发现
当溶液的pH从约9降低到3时，加热效率提高了约50％，这归因于PAA分子的盘绕-球状构象变化。在较高的pH下，羧酸基团的电离增加导致疏水性降低，从而导致界面热阻增加，从而在较高的pH下产生较低的磁热加热效率。提出的界面传热假设已通过热成像实验验证，其中在较高的pH值下传热速率较低。在低pH下观察到的提高的高温效率对设计用于多模式高温的有效pH响应纳米载体是有益的。
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