摘要
为提高顺铂的治疗效果并减少副作用,构建了一种具有化学-光热联合疗效的靶向铂药递送体系。以聚乙二醇-聚乳酸共聚物为载体,采用超声乳化法制备负载顺铂和光敏剂吲哚菁绿的纳米微球,再由西妥昔单抗进行表面修饰,从而制备西妥昔单抗修饰的近红外活化的载药纳米微球(CPINPs)。通过表征平均粒径、Zeta 电位、单抗偶联率、光热效应等考察其理化性质;通过激光共聚焦显微镜测定体外细胞摄取情况;通过CCK8实验评价体外抗肿瘤活性。结果表明,所制备的CPINPs纳米微球平均粒径为(263.9 ± 3.73) nm,多分散指数为0.18 ± 0.03,Zeta电位为-(23.43 ± 0.42) mV,单抗偶联率为(44.0 ± 1.72)%;体外光热实验显示,经近红外光照射后的CPINPs会产生导致肿瘤细胞死亡的光热效应;体外细胞摄取实验结果表明,近红外光对细胞摄取有促进作用,A549细胞会选择性地摄取更多受近红外照射过的CPINPs;体外细胞毒性实验表明,近红外光照射处理的CPINPs具有化学-光热联合治疗效果,其抑制A549细胞增殖的能力高过游离顺铂和无光照处理组,给药24 h的IC50为(8.67 ± 0.04) μmol/L。实验结果表明,本研究构建的多功能给药系统有望成为一种更为高效的肺癌靶向治疗方法。
化疗因其较高的治疗效率被公认为是肿瘤治疗的主要手段,但传统的化疗药物因选择性差、副作用大,无法满足临床需求。靶向纳米给药系统克服了传统治疗方法的局限性,在给药灵活性、低毒性和药物控释等方面显示出高于游离药物的临床优势。通过在纳米粒(NPs)的表面偶联抗体、核酸适配体、多肽等靶向因子,纳米粒的特异性能得到显著增强,能实现主动靶向给药目的,使肿瘤治疗进入精准靶向治疗时
光热疗法(PTT)是一种新型的非侵袭性肿瘤治疗方法。其利用光热剂在肿瘤中聚集的特性,通过激光照射刺激造影剂引起肿瘤细胞热损伤,进而导致肿瘤细胞变性坏死,具有时空选择性好、副作用小、侵袭性小等优
顺铂(cisplatin,CDDP)是1978年被FDA批准上市的第1个铂类抗肿瘤药物,广泛用于卵巢癌、乳腺癌、肺癌、头颈癌等实体瘤的治
顺铂(99%,山东铂源药业有限公司);西妥昔单抗(5 mg/mL,大连美仑生物技术有限公司);马来酰亚胺-聚乙二醇3400-聚乳酸34000(Mal-PEG3400-PLA34000)和甲氧基-聚乙二醇2000-聚乳酸8000(MPEG2000-PLA8000)(上海芃硕生物科技有限公司);CCK8试剂盒和DAPI染色液(碧云天生物技术研究所);annexin V-FITC细胞凋亡检测试剂盒(美国BD公司);其他试剂均为市售分析纯。
HT7700型透射电子显微镜(日本Hitachi公司);Nano ZS90型纳米粒度电位仪(英国Malvern Zetasizer公司);Ultrospec 7000型紫外可见分光光度计(美国GE公司);Optima 8000电感耦合等离子光谱质谱仪(美国PE公司);SP8激光共聚焦显微镜(德国Leica公司);FACSVerse流式细胞仪(美国BD公司);XthermT3红外热成像仪(合肥英睿系统技术有限公司)。
首先制备巯基化西妥昔单抗(Cetuximab-SH):向西妥昔单抗溶液(100 μL,5 mg/mL)中加入20倍过量的14 mmol/L 2-亚氨基噻吩(Traut′s试剂)室温反应1 h,加适量EDTA缓冲液(pH 8)透析、离心,用Ellmann′s试剂测定巯基数目。然后,参考文献[
超滤后的微球用磷钨酸溶液负染,自然晾干,用透射电子显微镜(TEM)观察其表观形态。用纳米粒度电位仪(DLS)测定25 ℃时微球的粒径、粒径分布、Zeta电位。用紫外-可见分光光度计测定微球中ICG的含量:取上述CPINPs溶液100 μL加入二甲亚砜(DMSO)3 mL超声,直至其结构被完全破坏为均一溶液,用紫外-可见分光光度计测定779 nm处的吸收度。用电感耦合等离子光谱质谱仪(ICP-MS)测定微球溶液中的铂元素含量,核算顺铂含量。包封率(EE)=(包裹的药物质量/最初加入的药物质量) × 100%,载药量(LE)=(包裹的药物质量/微球的质量) × 100%。
用BCA试剂盒测定CPINPs中西妥昔单抗的偶联
分别将CPINPs溶液(ICG质量浓度为40 μg/mL)1 mL、游离ICG溶液(40 μg/mL)、PBS溶液(pH 7.4)置1.5 mL离心管中,用近红外光(808 nm,1.6 W/c
选用EGFR抗原高表达的人非小细胞肺癌细胞株A549以及EGFR抗原阴性表达的人乳腺癌细胞株MCF-7进行细胞实
采用激光共聚焦显微镜(CLSM)观测靶向载药微球的细胞内在化过程及细胞内的分布情况。具体操作如下:将A549和MCF-7细胞按每孔5 × 1
采用CCK8实验测定靶向载药纳米微球CPINPs的细胞毒性,以顺铂和游离ICG为阳性对照,用GraphPad Prism软件计算IC50。具体操作如下:将A549细胞株按每孔5 × 1
采用自组装超声乳化法制备了基于西妥昔单抗的靶向载药微球CPINPs:超声下MPEG-PLA和Mal-PEG-PLA能很快在DCM溶液中混为均一透明溶液,当滴加进ICG和顺铂水溶液时,顺铂和ICG被包裹进入微球中,反应液逐渐变为均一、清澈的墨绿色。后经室温搅拌挥发除去DCM后,溶液仍为墨绿色。加入巯基化单抗与之反应,部分微球发生了团聚,但溶液颜色不变。如

Figure 1 Preparation scheme of cetuximab-decorated and near-infrared (NIR)-activated nanoparticles (CPINPs)MPEG-PLA: MPEG2000-PLA8000; Mal-PEG-PLA: Mal-PEG3400-PLA34000; CDDP: cisplatin; ICG: Indocyanine Green
微球的表观形态、粒径分布和Zeta电位如

Figure 2 Characterization of CPINPs
A: TEM images (bars represent 100 nm); B: Particle size distribution determined by DLS; C: Zeta potential distribution
采用电感耦合等离子光谱质谱仪测定了微球CPINPs中的铂元素含量,采用紫外-可见分光光度计测定了微球中的ICG含量,经计算:药物(以Pt计)包封率为(2.95 ± 0.21)%,载药率为(0.34 ± 0.08)%;ICG包封率为(61.5 ± 1.41)%,载药率为(7.70 ± 0.41)%。采用BCA试剂盒测得CPINPs微球表面西妥昔单抗的偶联率为(44.0 ± 1.72)%。
以PBS缓冲液(pH 7.4)和ICG溶液为对照,用红外热成像仪记录近红外光(808 nm,1.6 W/c

Figure 3 Photothermal effect of PBS, free ICG and CPINPs (NIR: 808 nm, 1.6 W/c
A: Time-dependent temperature increase profiles; B: Infrared thermographic images
西妥昔单抗能够通过抗体-抗原的特异性亲和作用有效地识别EGFR抗原高表达的肿瘤细胞,故本研究选择EGFR高表达的A549细胞和低表达的MCF-7细胞作对照实验,用CLSM检测微球CPINPs中西妥昔单抗的靶向能力及微球在近红外光激发下产生的光热效应。当向培养皿里的A549和MCF-7细胞中分别加入含相同ICG浓度的ICG或CPINPs溶液孵育3 h后,用DAPI对细胞核进行染色,用CLSM观测细胞形态和荧光。如

Figure 4 Cellular uptake of A549 cells and MCF-7 cells treated with free ICG, CPINPs (with or without NIR laser irradiation) observed by CLSM (Scale bars = 10 μm)
以CDDP和ICG为阳性对照,采用CCK8实验考察靶向纳米载药微球CPINPs抑制A549细胞增殖的能力。如

Figure 5 In vitro cellular viability of A549 cells after 24 h incubation with CDDP, Free ICG and CPINPs (with or without NIR laser irradiation) (
靶向给药是降低抗肿瘤药物的副作用的有效手段,化学-光疗联合治疗是提高药物抗肿瘤活性的重要策略。本研究设计合成了一种新型的既能靶向EGFR高表达肿瘤细胞,又具有化学-光热疗效的抗肿瘤药物微球CPINPs,并进行了体外评价。该微球是以MPEG-PLA和Mal-PEG-PLA为基材成核,核内包裹了小分子抗肿瘤药顺铂以及光敏剂吲哚菁绿,表面经西妥昔单抗修饰后而得。TEM显示微球为规则的球形,DLS测得平均粒径为(263.9 ± 3.73) nm。在西妥昔单抗的作用下,CPINPs能主动靶向EGFR抗原高表达的A549细胞并被其摄取进入细胞质;受808 nm近红外光激发核内ICG后,CPINPs升温效应明显,能产生光热效应,并具有化学-光热联合治疗效果;A549细胞给药24 h后IC50为(8.67 ± 0.04)μmol/L,优于游离顺铂。本研究可为其他高活性靶向抗肿瘤药物运输体系研发提供新思路。
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