University of Science and Technology of China ,No. 96, JinZhai Road, Baohe District, Hefei, Anhui 230026, P. R. China.
ACS Appl Mater Interfaces. 2017 Sep 13;9(36):30414-30425. doi: 10.1021/acsami.7b09124. Epub 2017 Aug 31.
Photoinduced reversible addition-fragmentation chain transfer (RAFT) polymerization generally adopts high-energy ultraviolet (UV) or blue light. In combination with photoredox catalyst, the excitation light wavelength was extended to the visible and even near-infrared (NIR) region for photoinduced electron transfer RAFT polymerization. In this report, we introduce for the first time a surface NIR-light-initiated RAFT polymerization on upconversion nanoparticles (UCNPs) without adding any photocatalyst and construct a functional inorganic core/polymer shell nanohybrid for application in cancer theranostics. The multilayer core-shell UCNPs (NaYF:Yb/Tm@NaYbF:Gd@NaNdF:Yb@NaYF), with surface anchorings of chain transfer agents, can serve as efficient NIR-to-UV light transducers for initiating the RAFT polymerization. A hierarchical double block copolymer brush, consisting of poly(acrylic acid) (PAA) and poly(oligo(ethylene oxide)methacrylate-co-2-(2-methoxy-ethoxy)ethyl methacrylate) (PEG for short), was grafted from the surface in sequence. The targeting arginine-glycine-aspartic (RGD) peptide was modified at the end of the copolymer through the trithiolcarbonate end group. After loading of doxorubicin, the UCNPs@PAA-b-PEG-RGD exhibited an enhanced U87MG cancer cell uptake efficiency and cytotoxicity. Besides, the unique upconversion luminescence of the nanohybrids was used for the autofluoresence-free cell imaging and labeling. Therefore, our strategy verified that UCNPs could efficiently activate RAFT polymerization by NIR photoirradiation and construct the complex nanohybrids, exhibiting prospective biomedical applications due to the low phototoxicity and deep penetration of NIR light.
光诱导可逆加成-断裂链转移（RAFT）聚合通常采用高能紫外（UV）或蓝光。结合光氧化还原催化剂，激发光波长扩展到可见光甚至近红外（NIR）区域，用于光诱导电子转移 RAFT 聚合。在本报告中，我们首次在没有添加任何光催化剂的情况下，在上转换纳米粒子（UCNP）上进行表面近红外光引发的 RAFT 聚合，并构建了一种功能性无机核/聚合物壳纳米杂化体，用于癌症治疗。具有链转移剂表面锚固的多层核壳 UCNP（NaYF:Yb/Tm@NaYbF:Gd@NaNdF:Yb@NaYF）可用作高效的 NIR 到 UV 光转换器，以引发 RAFT 聚合。依次从表面接枝了由聚（丙烯酸）（PAA）和聚（聚（氧化烯）甲基丙烯酸酯-co-2-（2-甲氧基乙氧基）乙基甲基丙烯酸酯）（简称 PEG）组成的分级双嵌段共聚物刷。通过三硫醇碳酸酯端基，将靶向精氨酸-甘氨酸-天冬氨酸（RGD）肽修饰在共聚物的末端。载药阿霉素后，UCNPs@PAA-b-PEG-RGD 表现出增强的 U87MG 癌细胞摄取效率和细胞毒性。此外，纳米杂化物的独特上转换发光可用于无自发荧光的细胞成像和标记。因此，我们的策略验证了 UCNP 可以通过近红外光辐照有效地激活 RAFT 聚合，并构建复杂的纳米杂化物，由于近红外光的低光毒性和深穿透性，具有潜在的生物医学应用前景。
