英国研究人员开发出一种有助治疗癌症的纳米微粒。在光动力疗法中，它可以携带大量光敏分子进入肿瘤，帮助杀灭癌细胞，其效果好于常规方法。
光动力疗法是指让一些对光敏感的分子进入到肿瘤中，然后用光照射，这些光敏分子就会产生有毒物质杀死癌细胞。现在常通过血液注射的方式来输送光敏分子，但注射液中多是彼此分散的单个分子，这样要使肿瘤部位出现较高的光敏分子含量就有难度。
英国赫尔大学的研究人员在美国期刊《分子药剂学》上报告说，他们开发出一种直径为几十个纳米大小的微粒，每个微粒可以携带上百个光敏分子，具有把光敏分子大量送达肿瘤部位的能力。在纳米微粒的内部和外部，还可以携带两种不同的光敏分子，进而增加光动力疗法的效果。
研究人员罗斯·博伊尔说，这种纳米微粒的形状经过精心设计，能进入肿瘤而不在健康组织中引起副作用。其原因是肿瘤中的血管与健康组织中的血管不太一样，其血管壁并不紧密，存在一些“漏洞”，纳米微粒可以在血压推送下穿过这些“漏洞”进入肿瘤。
研究人员已经用实验室培养的肿瘤组织进行了实验，结果显示这种纳米微粒可以增加光动力疗法对癌细胞的杀伤力。接下来研究人员将开展动物实验。（生物谷Bioon.com）
专题：MicroRNA 和 癌症
生物谷推荐原文出处：
Mol. Pharmaceutics DOI: 10.1021/mp200023y
Polyacrylamide Nanoparticles as a Delivery System in Photodynamic Therapy
Maheshika Kuruppuarachchi, Huguette Savoie, Ann Lowry, Cristina Alonso, and Ross W. Boyle
Nanoparticles can be targeted towards, and accumulate in, tumor tissue by the enhanced permeability and retention effect, if sequestration by the reticuloendothelial system (RES) is avoided. The application of nanoparticles in the field of drug delivery is thus an area of great interest, due to their potential for delivering high payloads of drugs site selectively. One area which may prove to be particularly attractive is photodynamic therapy, as the reactive oxygen species (ROS) which cause damage to the tumor tissue are not generated until the drug is activated with light, minimizing generalized toxicity and giving a high degree of spatial control over the clinical effect. In the present study, we have synthesized two types of nanoparticles loaded with photodynamic sensitizers: polylysine bound tetrasulfonato-aluminum phthalocyanine entrapped nanoparticles (PCNP) and polylysine bound tetrasulfonato-aluminum phthalocyanine entrapped nanoparticles coated with a second, porphyrin based, photosensitizer (PCNP-P) to enhance the capacity for ROS generation, and hence therapeutic potential. The mean sizes of these particles were 45 ± 10 nm and 95 ± 10 nm respectively. Uptake of the nanoparticles by human Caucasian colon adenocarcinoma cells (HT29) was determined by flow cytometry and confocal microscopy. Cell viability assays using PCNP-P and PCNP corresponding to the minimum uptake time (<5 min) and maximum uptake time (25 h) demonstrated that these cancer cells can be damaged by light activation of these photodynamic nanoparticles both in the external media and after internalization. The results suggest that, in order to induce photodynamic damage, the nanoparticles need only to be associated with the tumor cell closely enough to deliver singlet oxygen: their internalization within target cells may not be necessary. Clinically, this could be of great importance as it may help to combat the known ability of many cancer cells to actively expel conventional anticancer drugs.
Keywords: PDT; porphyrins; phthalocyanine; nanoparticles; drug delivery
