异丙基丙烯酰胺水凝胶纳米微球粒径的控制及其对多肽吸附的影响

采用沉淀聚合法制备了一系列聚（N-异丙基丙烯酰胺-co-N-叔丁基丙烯酰胺-co-丙烯酸）（P-NIPAm-tBAm-AAc）水凝胶纳米微球（NPs），分散性好且粒径可控。通过调整配方，其水动力学直径可控制在71~304 nm之间，经动态光散射（DLS）表征，PDI值均小于0.1。由于电荷斥力的作用，亲电单体丙烯酸（AAc）的用量从5%增加到50%（摩尔分数），粒径从71 nm增大至219 nm；而疏水单体叔丁基丙烯酰胺（tBAm）的使用，使微球的粒径趋于变小；表面活性剂十二烷基磺酸钠（SDS）的量增大，NPs的粒径逐渐减小，最小可达71 nm。将所制备的NPs用于多肽（LEVLFQGP）的吸附，结果表明，吸附率随NPs粒径的减小而增大，并且与聚合物的配方有关，当AAc的摩尔分数为20%、粒径为128 nm时，吸附率为90%。经DLS表征，NPs的体积相变温度（LCST）为(20±2)℃，因此分别在35℃和5℃下对多肽进行吸附/解吸，5次循环实验后，吸附率降低小于7%。本研究探索了水凝胶纳米微球粒径的影响因素及粒径对目标多肽亲和性的影响，可作为制备尺寸均一、粒径可控水凝胶纳米微球的参考。

Influences on diameter of isopropylacrylamide hydrogel nanoparticles and its effect on peptide affinity

A library of poly(N-isopropylacrylamide-co-N-tert-butylacrylamide-co-acrylic acid) (P-NIPAm-tBAm-AAc) hydrogel nanoparticles with good dispersion and uniform size were prepared by precipitation polymerization method. Their hydrodynamic diameters were controlled from 71 nm to 304 nm proved by dynamic light scattering (DLS) with adjusting the polymerization formulation, while the PDI values are all below 0.1. Due to the charge repulsion, the particle size increased from 71 nm to 219 nm when the feeding of electrophilic monomer AAc increased from 5% to 50%(mol) in polymerization. Meanwhile, the inverse effect was also revealed on the hydrophobic monomer tBAm, that is, the nanoparticle size decreased along with increasing its feeding ratio. Besides, the increased usage of the surfactant SDS resulted in the microspheres being smaller to 71 nm. It is proved that the NPs size greatly affected their affinity to the target peptides (LEVLFQGP), and the results showed that the adsorption rate increased with decreasing the nanoparticle size. When the molar ratio of AAc was 20% and the diameter was 128 nm, the adsorption rate could reach 90%. Furthermore, the adsorption and desorption experiment was performed with changing the environmental temperature from 35℃ to 5℃ since the volume phase transition temperature (LCST) of NPs is (20±2)℃ proved by DLS. After five times adsorption/desorption circulation experiments, the reduction of NPs adsorption rate on target peptide was below 7%. Therefore, the prepared and screened NPs are size controlled and reusable.