Osteoporosis is an illness which appears when the osteoblast/osteoclast activities are unbalanced taking place bone resorption (caused by osteoclasts) in higher extension than bone formation (induced by osteoblasts). Alendronate is one of the most used drugs for osteoporosis treatment despite its scarce bioavailability. Here we present the synthesis and characterization of mesoporous gated nanoparticles (two sets) for the controlled release of alendronate. The first set of nanoparticles (S1) were loaded with sulforhodamine B and capped with a peptide that could be selectively hydrolyzed by cathepsin K enzyme (overexpressed in osteoclasts). The second set (S2) was functionalized with aminopropyl moieties, loaded with nitrobenzofurazan labelled alendronate and capped with the same peptide. Both nanoparticles were internalized by RAW 264.7 macrophages (which could differentiate in osteoclasts) and were able to release its entrapped cargo in the presence of cathepsin K added in the macrophage lysates. Using S2 nanoparticles 4.2% of the total alendronate amount in contact with the cells is liberated inside them and could produce its therapeutic effect.

中文翻译：

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肽封端的中孔纳米颗粒：旨在提高阿仑膦酸盐的内在化

骨质疏松症是一种疾病，当成骨细胞/破骨细胞的活动发生失衡，而发生的骨吸收（由破骨细胞引起）的扩展性高于骨骼形成（由成骨细胞引起）的扩展时。阿仑膦酸盐尽管生物利用度不足，但它是治疗骨质疏松症最常用的药物之一。在这里，我们介绍了阿仑膦酸盐控释的介孔门控纳米颗粒（两组）的合成和表征。第一组纳米颗粒（S1）装有磺基罗丹明B，并用可被组织蛋白酶K酶（在破骨细胞中过表达）选择性水解的肽封端。第二套（S2）用氨基丙基部分官能化，负载了硝基苯并呋喃山标记的阿仑膦酸盐并用相同的肽封端。两种纳米颗粒均被RAW 264.7巨噬细胞（可能在破骨细胞中分化）内化，并且能够在巨噬细胞裂解物中添加的组织蛋白酶K的存在下释放其包裹的货物。使用S2纳米颗粒，与细胞接触的总阿仑膦酸盐量的4.2％在细胞内部释放，并可以产生治疗效果。