文献：A Dual pH-Responsive DOX-Encapsulated Liposome Combined with Glucose Administration Enhanced Therapeutic Efficacy of Chemotherapy for Cancer.

文献链接：https://xueshu.baidu.com/usercenter/paper/show?paperid=13180v605p1n0mf01t640tq06c662337&site=xueshu_se

作者：Luoping Zhai,Chuangwei Luo ,Hannan Gao,Shuaifan Du,Jiyun Shi ,Fan Wang

相关产品：DSPE-PEG2000-MAL 磷脂-聚乙二醇2000-马来酰亚胺

原文摘要：Background: The acidic microenvironment of cancer can promote tumor metastasis and drug resistance. Acidic tumor microenvironment-targeted therapy is currently an important means for treating tumors, inhibiting metastasis, and overcoming drug resistance. In this study, a dual pH-responsive DOX-encapsulated liposome (DOPE-DVar7-lip@DOX) was designed and fabricated for targeting the acidic tumor microenvironment. On the one hand, the response of acid-sensitive peptide (DVar7) to the acidic tumor microenvironment increased the uptake of liposomes in tumors and prolonged the retention time; on the other hand, the response of acid-sensitive phospholipid (DOPE) to the acidic tumor microenvironment improved the controlled release of DOX in tumors.

Methods: The acid-sensitive peptide DVar7 modified liposomes can be obtained by simple incubation of DSPE-DVar7 with DOX-loaded DOPE liposomes (DOPE-lip@DOX). The tumor targeting of the dual pH-responsive liposome was investigated in vitro and in vivo by near-infrared fluorescence imaging. The tumor therapeutic efficacy of DOPE-DVar7- lip@DOX was evaluated in breast cancer mouse model using the traditional liposome as a control. Moreover, we regulated the tumor microenvironment acidity by injecting glucose to further enhance the therapeutic efficacy of cancer.

Results: DVar7 can allosterically insert into the tumor cell membrane in the acidic tumor

microenvironment to enhance the tumor uptake of liposomes and prolong the retention time of liposomes in tumor. In addition, the therapeutic efficacy of pH-responsive liposomes can be further enhanced by glucose injection regulating the acidity of tumor microenvironment. Discussion: DVar7 modified acid-sensitive nanocarriers combined with acidity regulation have great potential to improve drug resistance in clinical practice, thus improving the response rate and therapeutic effect of chemotherapy.

DSPE-PEG2000-MAL从化学组成来看，它是由1,2-二硬脂酰-sn-甘油-3-磷酸乙醇胺（DSPE）、聚乙二醇（PEG，分子量为2000）和马来酰亚胺（MAL）组成。DSPE作为一种磷脂成分，赋予了该分子良好的脂质体形成能力和与细胞膜的亲和性。PEG2000链具有高度的亲水性，一方面能够增加分子在水性环境中的溶解性和稳定性，另一方面可有效减少非特异性蛋白吸附。而MAL基团则为其提供了特异性的化学反应活性位点，能够与含有巯基的生物分子，如蛋白质、多肽等通过迈克尔加成反应进行高效偶联。可用于构建靶向载体、生物传感器等。基于此该文献设计制备双ph响应dox封装脂质体（DOPE-DVar7-lip@DOX）。过程如下：

图：DOPE-DVar7-lip@DOX的制备及其作用机制。

DSPE-PEG2000-DVar7的合成

通过将DSPE-PEG2000-马来酰亚胺与DVar7的n端单个半胱氨酸残基共价结合，合成了DSPE-PEG2000-DVar7。简单地说，将DSPE-PEG2000-MAL溶解在氯仿中，并在圆瓶中蒸发形成薄膜。用HBS溶液（pH 7.0）水合膜，并超声。将DVar7 加入混合物中，并振荡至完全溶解后，用反相高效液相色谱（HPLC）体系分离混合物。

DSPE-DVar7-DVar7-lip@Cy5.5脂质体的制备

采用薄膜水化法制备了ph响应p乙二醇化脂质体（pSPL）和非ph响应脂质体（nSPL）。首先，制备荧光脂质体DOPE-DVar7-lip@Cy5.5。将不含DSPE-PEG2000- DVar7的所需脂质混合物氯仿溶液涡旋蒸发，在配备旋转蒸发器的圆瓶中形成薄膜，继续蒸发以去除残留的有机溶剂。然后，用 HBS溶液水合膜，形成多细胞囊泡（MLVs）。MLVs用微型超声探头进行超声形成小的单层囊泡，将DSPE-PEG2000-DVar7与荧光脂质体DOPE-lip@Cy5.5混合，制备DSPE-DVar7-DVar7-lip@Cy5.5。脂质体通过滤器过滤保存。

图：MDA-MB-435S细胞与游离DOX和装载DOX的脂质体孵育1小时的 CLSM图像

结论：DSPE-PEG2000-MAL 参与制备的双ph响应dox封装脂质体（DOPE-DVar7-lip@DOX），比传统脂质体和单ph响应脂质体提高。此外，通过应用于临床可实施的葡萄糖来调节TME的pH值，可以进一步提高双ph响应脂质体的效果。