Beijing Key Laboratory of Polymorphic Drugs,Institute of Materia Medica,Chinese Academy of Medical Sciences,Beijing 100050,China 通信作者 张丽(1981-),女,河北石家庄人,副研究员,硕士生导师,博士,研究方向:晶型药物与药物质量控制及检测分析方法研究。电话:010-63165310,E-mail: [email protected] 。吕扬(1959-),女,北京人,研究员,博士生导师,学士,研究方向:晶型药物与药物质量控制及检测分析方法研究。电话:010-63165212, E-mail: [email protected] 。

作者简介 王若楠(1995-),女,河北石家庄人,硕士,研究方向:药物多晶型与共晶研究。ORCID:0000-0003-3885-221X。电话:010-63165310,E-mail: [email protected] 。

Nanocrystalline drugs,based on the combination of nanotechnology and crystal technology, are expected to improve the solubility and the druggability, and reduce side reactions. The stability control and the combination of nanocrystalline drugs and polymers have great application values in the field of sustained and controlled release preparations and targeted drug delivery. This paper introduces the related concepts, preparation methods, influencing factors of nanocrystalline drugs, and discusses the current research progress and the prospects by consulting relative domestic and foreign literatures.

目前合成获得的新化合物中70%~90%存在溶解度差的问题 ^{[ 1 ]} ,成为阻碍新药研发的一个重要因素。科学工作者想尽一切办法来提高具有活性化合物的溶解度,其中一种受欢迎的方法是减小药物粒径,纳米药物应运而生。另一种解决办法与药物晶型研究相关,药物间的多晶型现象不仅会影响药物理化性质,如熔点和密度,同样也会使药物的成药性有所差异,如稳定性、溶解性和生物利用度。通过对药物晶型的研究,可以筛选出安全性、稳定性和有效性高的优势药物晶型,成为解决药物溶解度问题的一个有效方法。纳米技术指在1~100 nm的尺度里研究电子、原子、分子内的运动规律和特性,其与药物多晶型成因之一分子排列规律有着一定的交叉,两者的结合,不仅可以改善化合物的溶解度问题,对影响药物成药性的很多因素也具有一定的改善作用。因此,纳米晶药物应运而生,药物在纳米尺度和晶型技术上的共同开发在制药行业有着广阔的应用前景,该技术的出现吸引了更多研究者的关注。

1.1 纳米晶药物

纳米晶药物,是指尺寸小于1 μm、无载体、含少量稳定剂,溶解速度和饱和溶解度提高,能够稳定存在的晶态或无定型态药物 ^{[ 2 ]} 。纳米晶药物常以结晶态分散粒子形式存在,当以液态形式存在时,称为纳米晶混悬液,其包括了纳米晶、稳定剂和液体分散介质。在纳米晶药物的机制研究中,根据Noyes-Whitney和Freundlich-Ostwald方程 ^{[ 3 ]} ,当药物粒径减小到纳米级别时,其表面积大大增加,而溶出速率和饱和溶解度会随着表面积增加而增大,生物利用度也随着药物与肠壁接触面积增大和药物黏附性增加而显著提高。

在解决难溶性药物溶解度问题上,涌现了许多方法,如混合溶剂系统的选择、制成分子水平的前药、成盐、环糊精包合、载体类纳米递送系统应用、药物微粉化等 ^{[ 4 ]} 。传统方法中由于混合溶剂系统的使用、微粉化、成盐技术应用范围狭窄等的不足,前药的开发常存在生物利用度低、不稳定的问题,环糊精的包合及载体类纳米递送系统应用载药量低、患者存在服药风险等问题。而纳米晶药物不含任何基质材料,仅含少量稳定剂,几乎为纯固体药物微粒。具有载药量高、易于产业化,粒径小的优势,并可选择多种给药方式,如口服、注射、透皮给药、肺部及眼部给药等 ^{[ 5 ]} ,见 表1。纳米晶药物因减少了配方开发中可能出现的副作用和不良反应,降低了服药者面临的风险而受到了更多关注。但纳米晶药物作为新兴研究方向,仍有大量研究工作亟待开展,在控速和靶向研究方向均可向目前研究相对成熟的纳米递送系统借鉴。

生物药剂学分类系统中二类药物又可细分为两类 ^{[ 7 ]} :一是溶出率限制类,即砖尘分子,不仅难溶于水,在脂质和有机溶剂中溶解性也很差;二是溶解度限制类,即油脂球分子,可溶于部分脂质中。所以,砖尘分子类药物是纳米技术的主要应用对象之一。纳米技术的应用可以为低溶解性药物商业化开发独辟蹊径 ^{[ 4 ]} 。

纳米技术的应用使得溶解度提高,从而改善吸收速度,使得具有优势晶型药物的快速吸收成为可能。在某些药物需要进食后服用来达到较高吸收程度的情况下,纳米晶药物有望消除空腹和饱腹后服用药物对药物吸收的影响 ^{[ 2 ]} 。另外,纳米晶技术的应用有助于实现使用更少剂量的药物来达到相同的治疗效果,从而降低副反应发生的可能性。

2 纳米晶药物的制备方法 2.1 粉碎技术

粉碎技术又称为Top-down法,是指利用外力将大颗粒的药物粉碎得到纳米晶。主要包括湿法介质研磨和高压均质2种技术 ^{[ 5 ]} 。

湿法介质研磨,是将药物分散于含有稳定剂的水中形成药物的大颗粒混悬液,然后将其加入到研磨机中,靠研磨珠降低药物粒径。该法具有低能量的优势,且当前已有利用湿法介质研磨的纳米晶药物上市。但也存在着一些问题,如研磨过程漫长,批量制备受限于设备容量,研磨过程中研磨珠的碎屑可能掉落,污染产品。其中碎屑掉落问题可通过高度交联的聚苯乙烯树脂对研磨珠进行包衣来解决 ^{[ 8 ]} 。MERISKO-LIVERSIDGE等 ^{[ 9 ]} 利用湿法介质研磨技术制备水不溶性抗肿瘤药物的纳米晶混悬液,其选用了4种不同的化疗药物:吡泊磺、依托泊苷、喜树碱和紫杉醇。采用低能量球磨机,加入了含1%表面活性剂和2%稳定剂的固体悬浮液进行湿法研磨,3~4 d后对纳米晶悬浮液的粒径、物理稳定性和性能进行了评价。结果表明将难溶性抗癌药物制备成物理稳定的水纳米晶悬浮液是可行的,静脉注射后通过血浆检测证实悬浮液仍能保持物理稳定性和有效性。

高压均质,即通过高压使得药物大颗粒混悬液进入细的管腔,达到减小粒径的目的。该法不使用有机溶剂,快速,可大批量生产,易于工业化,批间差异小,使用广泛。但需要高能量,需要有经验的技术人员专门操作,操作要求严格。杜俊峰等 ^{[ 10 ]} 采用高压均质法成功制备了葛根素纳米晶,解决了葛根素溶解性差、生物利用度低的问题。目前许多上市的纳米晶药物制备均涉及了高压均质技术。

湿法介质研磨和高压均质研磨技术在纳米晶药物生产上应用广泛,且均已有上市药品。这两种技术的发展较为成熟,将来或许可以提高生产效率、改善经济效益。

2.2 自组装技术

自组装技术又称为Bottom-up法,是通过控制药物分子的结晶过程,得到粒径处于纳米级别的药物晶体。主要是通过沉淀形式从过饱和溶液中结晶,也称反溶剂法。首先将药物溶解于溶剂中,通常是与水互溶的有机溶剂,之后加入反溶剂,通常是水,来达到药物结晶析出的目的。此过程中需要加入合适的稳定剂,利用超声或者搅拌使晶粒分散不聚集,以控制成核粒径 ^{[ 11 ]} 。该法可以使药物得到很好的分散,对粒径有着更好的控制效果。崔福德等 ^{[ 12 ]} 通过控制药物浓度和稳定剂含量,利用沉淀法制备了不同粒径的尼群地平纳米晶,经表征其晶型未改变。研究结果显示,纳米晶的平衡溶解度随着粒径的减小而略有增加,生物利用度在粒径<2.7 μm范围内随着粒径减小而显著增加。

但是应用纳米技术的药物本身存在溶解度问题,在反溶剂法中寻找合适的溶解溶剂和难溶溶剂的组合对新药开发无疑又产生了新问题。另外,反溶剂法使用了有机溶剂,残留溶剂也使其应用受到了限制。目前多应用于材料和稀土资源研究中,与高压均质法联合使用也较多,在药物实际生产中独立应用较少。

应用超临界流体技术可弥补反溶剂法的不足。超临界流体基于溶剂去除或液体雾化技术 ^{[ 13 , 14 ]} ,先将药物溶解在超临界液体(如CO ₂ )中,当液体通过微小孔径的喷嘴雾化时,随着超临界液体气化而析出纳米晶粒子 ^{[ 15 ]} 。该技术使用无害溶剂,可制备出高纯度的无任何有机溶剂残留的纳米晶,但也存在超临界流体消耗大,且不适用于在超临界流体中不溶解的药物。其中液体雾化技术由于溶剂的快速去除可能产生无定型态,而影响稳定性。

2.3 组合技术的应用

Top-down法和Bottom-up法各有所长,虽然Bottom-up法中沉淀法单独使用较少,但由于成本相对较低,与Top-down中的高压均质技术联合使用受到了药物生产企业的关注。组合技术增加了整个生产过程的复杂性,只有在能够改善产品成药性时才有应用价值 ^{[ 16 ]} 。百特公司的Nanoedge技术首先使用反溶剂法进行沉淀预处理,之后使用高压均质技术制备纳米晶产品。在该专利技术中,高压均质使热力学不稳定形式转化为稳定形式 ^{[ 17 ]} 。雅培公司开发的SmartCrystal是一系列组合技术,考虑到每种药物物理性质不同,量身定制了纳米晶生产工艺。高压均质法结合了不同的预处理,如喷雾干燥、沉淀、冻干等,使得粉末更容易破裂纳米化 ^{[ 18 ]} 。Top-down和Bottom-up组合技术规避了研磨和均质法中制备时间长的特点,避免了沉淀法晶体熟化问题,成本相对较低,在实际应用中有着独有的优势。

3 纳米晶药物制备的影响因素 3.1 稳定剂

纳米晶生产过程中为了避免在固化过程中纳米晶粒重新聚集降低溶出速率和生物利用度,通常会加入稳定剂来保持其粒径。典型的稳定剂包含不同种类的聚合物,如纤维素衍生物、聚乙烯吡咯烷酮(PVP)、泊洛沙姆或两亲性表面活性剂,如聚吸附剂、十二烷基硫酸钠 ^{[ 19 , 20 ]} 。好的稳定剂应满足两个条件:一要能够紧密吸附于纳米晶表面,需要稳定剂和药物之间有较强的分子间相互作用,其中疏水作用为主,如果存在氢键等强相互作用,稳定效果更好;二要具有适宜的亲水亲油平衡值,因为疏水性太强,尽管可以紧密吸附在纳米晶表面,但较差的亲水性会导致较高表面能,稳定效果不理想,因此要有适中的亲水亲油平衡值。

稳定剂的选择不仅要考虑在制备纳米晶药物后应保持一定粒径,还要考虑后续制剂生产过程中附加的作用,例如冻干过程中可以充当保护剂的角色 ^{[ 21 ]} 。另一方面稳定剂的选择应考虑到对生物利用度的影响,许多聚合物和表面活性剂被用作稳定剂是因为其可以影响细胞活性。如打开细胞间通道,使细胞层更易渗透。许多稳定剂对递送系统也有影响,例如P-gp抑制剂具有黏附性,可以延长在身体某部位的停留时间。这一定程度上提高了生物利用度 ^{[ 22 ]} 。针对紫杉醇药物溶解度低、代谢快、吸收效果差的不足,SHARMA等 ^{[ 23 ]} 使用普朗尼克与壳聚糖的共聚物作为紫杉醇纳米晶的稳定剂,使生物利用度显著提高。稳定剂对于药物的针对性应用以提高生物利用度将成为后续研究的一个方向。

3.2 Top-down中工艺参数的影响

湿法介质研磨的影响因素有研磨时间、速度、研磨球材质、粒径、球料比及介质浓度 ^{[ 24 ]} 。搅拌速度和球料比增加通过更高的比能和研磨强度因子会导致更快的破碎,而药物负载量的增加具有相反效果。高压均质法的影响因素主要有压力、循环次数、温度、药物自身性质等 ^{[ 25 ]} 。XIONG等 ^{[ 26 ]} 采用高压均质法制备尼莫地平纳米晶混悬液,研究了压力、循环次数、破碎原理(微射流技术和活塞-裂隙均质技术)等生产参数对纳米混悬液的平均粒径、99%直径、破碎速度和分散性的影响。结果显示,微射流技术对具有延展性的药物具有更好的均质效应,对硬性材料效果则较差;均质压力在(5×10 ⁷ ~15×10 ⁷ )Pa随着压力增大粒径在减小,但当压力再次升高时,粒径变化不再明显;随着循环次数增加,99%直径在减小,而平均粒径的降低则趋于一致。

3.3 Bottom-up中工艺参数的影响

应用Bottom-up需要注意制备过程中工艺参数,包括药物在溶剂中的浓度、溶剂与反溶剂体积比、搅拌时间、超声时间、结晶温度等。XIA等 ^{[ 27 ]} 对影响尼群地平纳米晶药物生产的因素进行了考察,结果显示,药物和聚乙烯醇(PVA)的浓度与粒径大小并不单纯呈反比,存在一个浓度区域可获得最小的粒径。在超声影响考察中,发现超声输入功率越大越有助于降低粒径,但增大到一定功率时粒径减小的效果不再显著。而超声时间以15 min为宜,过短使得分散不均匀,过长则造成能源浪费。沉淀温度在3 ℃时所形成的粒径远远小于35 ℃时,温度降低限制了分子热运动,减少了分子团聚。

纳米晶药物制备的影响因素考察不仅有助于纳米晶药物制备工艺的完善,而且对提高纳米晶药物生产效率有着积极的指导意义。

4 纳米晶药物研究现状 4.1 纳米晶药物的分析技术

在生产纳米晶的过程中,由于表面积增大,使得体系形成热力学不稳定体系,容易发生晶粒聚集以降低体系自由能的现象,直接表现为粒径增大。纳米晶的粒径检测对评估体系的物理稳定性具有重要意义 ^{[ 28 ]} ,目前可通过动态光散射技术、扫描电镜、透射电镜等对纳米晶粒径进行表征。

某些药物因为具有较弱的弹性指数,在制备纳米晶过程中极可能发生转晶,影响后续制剂产品的质量。因此,在纳米晶药物的生产过程中对晶型的分析必不可少。常用分析技术有粉末X射线衍射技术(PXRD)、单晶X射线衍射技术、热分析技术、红外技术、拉曼技术等。其中X射线衍射技术是判断纳米晶药物晶型是否发生改变的权威技术手段。

纳米晶药物-聚合物的组合在药物递送中具有重要的应用价值,组合物的检测技术也在与时俱进。VOGT等 ^{[ 29 ]} 基于二维和多核固态磁共振(SSNMR)方法对新型纳米晶药物分散体依布硒啉与聚乙烯吡咯烷酮-醋酸乙烯酯的适用性进行研究,并采用其他技术进一步分析。PXRD分析表明,在35~60 nm范围内分散体中含有纳米晶依布硒啉。共焦拉曼显微镜和光谱映射能够检测出依布硒啉与聚乙烯吡咯烷酮-醋酸乙烯酯之间可能发生短程相互作用的区域。利用二维SSNMR实验分析了自旋扩散效应,直接检测依布硒啉与周围聚乙烯吡咯烷酮-醋酸乙烯酯的相互作用。在该研究中,基于自旋扩散的二维SSNMR方法提供了关于依布硒啉纳米晶聚合物分散体的详细结构信息。这也提示该技术可用于检测更长距离的介于药物和聚合物之间的自旋扩散和相互作用。

随着纳米晶药物的发展和新技术新方法的应用,相信纳米晶药物的分析技术会得到进一步的拓展和完善。

4.2 无定型药物的转晶研究

目前采用纳米技术制备获得了许多无定型药物,由于其在稳定性上的不足,使得其转晶过程研究成为了科学问题。

研究发现以甘露醇和薄荷醇作为添加剂,分别经过冻干和超临界CO ₂ 法,可以实现无定型药物的转晶 ^{[ 30 , 31 ]} 。但冻干和超临界法能耗大、成本高,寻找更加经济有效的方法至关重要。张智亮等 ^{[ 32 ]} 研究了伊曲康唑纳米晶药物制备过程中的无定型转晶过程。在该实验中,其以泊洛沙姆407为添加剂,转晶时间10 min,高压均质压力100 MPa,均质次数15的条件下将无定型转为结晶颗粒。经喷雾干燥得到的超细晶体颗粒晶型与原料药保持一致,溶出度远优于原料药。该方法简单、无毒副作用,有望在实际生产中应用。张智亮等 ^{[ 33 ]} 在对厄贝沙坦无定型转晶过程研究中,采用3种表面活性剂泊洛沙姆、PVP和羟丙甲纤维素作为转晶剂。结果显示,只有泊洛沙姆可使无定型药物转晶。

以上研究表明,通过控制添加剂、转晶时间、温度、高压均质过程等条件可以实现无定型药物的转晶,而是否存在标准化操作及条件使得转晶过程顺利实现还需要进行大量的转晶条件研究实验。

5 纳米晶药物的展望 5.1 稳定性的改善

纳米晶药物大多呈现无定型态,而无定型态溶解度一般优于晶态,如果能解决无定型态的稳定性问题,将有助于提高成药性。

VUDDANDA等 ^{[ 34 ]} 采用高压均质法制备了他达拉非纳米晶混悬液,将其负载于口服用聚合物薄膜上,并研究了表面活性剂和载药量对薄膜物理性能和药物溶解性的影响。结果表明,他达拉非在薄膜上可保持在纳米范围内,表面活性剂的使用有利于纳米晶的分布、稳定、再分散。提示了在他达拉非无定型分散体中,与聚合物薄膜结合可能是一种有效方法,既能保持纳米晶药物的良好溶解性又能解决稳定性问题。

这也启示我们对无定型纳米晶药物不一定非要找到转晶办法,可以借助聚合物等载体技术使无定型药物能够在有效期内保持稳定。目前对无定型药物的稳定性改善研究尚显不足,需要更多的关注和深入研究。

5.2 制备控速的实现

纳米晶药物由于粒径减小,其溶出速率会明显加快。但影响药物在体内发挥作用的因素很多,快速溶出并不意味着高效吸收。当药物溶出速度过快可能出现药物还未吸收并发挥作用即被代谢出体内,因此纳米晶药物溶出速率的控制具有极大的研究价值。

CIPOLLA等 ^{[ 35 ]} 通过调整脂质体包裹纳米晶药物环丙沙星来实现药物释放速度的控制。通过冻融前加入表面活性剂以控制脂质体囊泡内包封纳米晶药物含量,冻融后转化为脂质体囊泡内包含单个纳米晶药物的形式。从而实现对药物释放速率的控制。

纳米晶纤维素是可从自然界中获取的纳米材料,具有绿色环保、良好的生物相容性和降解性、较高生物利用度和渗透率的特点。对于易溶药物,可以控制对药物的释放,对难溶药物也可以达到增溶的目的 ^{[ 36 , 37 , 38 , 39 , 40 ]} 。在解决控制药物释放问题上,纳米晶药物和纳米晶纤维素有望成为高效结合方式。

同时,纳米晶药物溶出速率的控制可通过与其他聚合物的结合实现。而通过控制纳米晶药物的粒径使得其溶出速率得到控制也是一个研究方向,其是否具有普适性及条件的控制还需要实验加以确证。

5.3 靶向性的提高

PANDEY等 ^{[ 41 ]} 合成了一种硫酸软骨素A-聚乙二醇共轭物,并将其作为制备多西紫杉醇纳米晶的稳定剂。其中硫酸盐又作为靶向配体 ^{[ 42 , 43 , 44 ]} ,与治疗肿瘤中具有稳定性、隐蔽性、肿瘤靶向性的跨膜糖蛋白CD44受体联合作用。纳米晶药物、靶向配体、跨膜糖蛋白三者合一,形成了多西紫杉醇纳米晶体系。其渗透性强、稳定性好,能够深层次地穿透肿瘤细胞,有望成为更好的化疗方案。LIU等 ^{[ 45 ]} 将生物降解陶瓷/聚合物纳米复合材料作为新型的药物载体用于骨科治疗,延长了局部药物释放时间从而提高了骨病部位的药物疗效。这提示了利用复合材料与纳米晶药物结合,可实现药物在有效部位持续释放,避免正常组织受到影响。

目前纳米晶药物靶向性是通过与配体结合实现的,对配体的发现及靶向作用的评价仍然是一个重要研究方向。纳米粒径不同使药物富集在不同部位可实现不同治疗效果。在制备方法上通过控制粒径使得药物在有效部位聚集,不仅可以使治疗效果增强,而且减少了非靶向部位的吸收,减少了副作用。关于纳米晶药物粒径控制与靶向作用的研究还有待进一步深入,实现药物的缓控释也是纳米晶药物今后研发的重要方向。

综上,纳米晶药物的稳定性、控速及靶向性研究还需要结合辅料、聚合物、复合材料、靶向配体等技术加以改善,而辅助技术的选择仍需要后期大量实验进行深入研究。

6 结束语

纳米晶药物的出现从药物粒径尺度解决了难溶性药物的部分后续开发问题,对于新药的研究具有较好的促进作用。纳米晶药物不含基质材料的特点,使得降低剂量和毒副作用成为可能。目前,对于纳米晶药物的研究集中在了制备方法和转晶条件的探索上,制备方法渐趋完善,但制备效率的提高还需要继续研究。纳米晶药物结合其他技术实现更好疗效——如缓控释、靶向控制等在未来是值得密切关注的一个方向。纳米晶药物在体内的生物学性质研究相对缺乏,有待后续拓展、完善。我国对于纳米晶药物的研究刚刚起步,国产纳米晶原研药物还没有上市品种,在该研究领域我们还有很长的路要走。

MU LLER RH , KECK CM . Twenty years of drug nanocrystals:where are we, and where do we go [J]. Eur J Pharm Biopharm, 2012 , 80 ( 1 ): 1 - 3 . DOI: 10.1016/j.ejpb.2011.09.012 PMID: 21971369 [本文引用:1] JUNGHANNS J U , MU LLER R H . Nanocrystal techno-logy, drug delivery and clinical applications [J]. Int J Nanomed, 2008 , 3 ( 3 ): 295 - 309 . [本文引用:2] 王廉卿 , 戎欣玉 , 刘魁 , 等 . 纳米药物晶体的制备技术及其应用 [J]. 河北科技大学学报, 2014 , 35 ( 4 ): 339 - 347 . [本文引用:1] PELTONEN L , HIRVONEN J . Drug nanocrystals-Versatile option for formulation of poorly soluble materials [J]. Int J Pharm, 2018 , 537 ( 1/2 ): 73 - 83 . [本文引用:2] 周小圆 , 林华庆 , 雷伟 . 难溶性药物纳米晶体的研究进展 [J]. 中南药学, 2013 , 11 ( 5 ): 353 - 358 . [本文引用:2] BOBO D , ROBINSON KJ , ISLAM J , et al . Nanoparticle-based medicines:a review of FDA-approved materials and clinical trials to date [J]. Pharm Res, 2016 , 33 ( 10 ): 2373 - 2387 . In this review we provide an up to date snapshot of nanomedicines either currently approved by the US FDA, or in the FDA clinical trials process. We define nanomedicines as therapeutic or imaging agents which comprise a nanoparticle in order to control the biodistribution, enhance the efficacy, or otherwise reduce toxicity of a drug or biologic. We identified 51 FDA-approved nanomedicines that met this definition and 77 products in clinical trials, with ~40% of trials listed in clinicaltrials.gov started in 2014 or 2015. While FDA approved materials are heavily weighted to polymeric, liposomal, and nanocrystal formulations, there is a trend towards the development of more complex materials comprising micelles, protein-based NPs, and also the emergence of a variety of inorganic and metallic particles in clinical trials. We then provide an overview of the different material categories represented in our search, highlighting nanomedicines that have either been recently approved, or are already in clinical trials. We conclude with some comments on future perspectives for nanomedicines, which we expect to include more actively-targeted materials, multi-functional materials ( DOI: 10.1007/s11095-016-1958-5 PMID: 27299311 [本文引用:1] BUTLER J M , DRESSMAN J B . The developability classi-fication system:application of biopharmaceutics concepts to formulation development [J]. J Pharm Sci, 2010 , 99 ( 12 ): 4940 - 4954 . A revised classification system for oral drugs was developed using the biopharmaceutics classification system (BCS) as a starting point. The revised system is designed to have a greater focus on drug developability. Intestinal solubility, the compensatory nature of solubility and permeability in the small intestine and an estimate of the particle size needed to overcome dissolution rate limited absorption were all considered in the revised system. The system was then validated by comparison with literature on the in vivo performance of a number of test compounds. Observations on the test compounds were consistent with the revised classification, termed the developability classification system (DCS), showing it to be of greater value in predicting what factors are critical to in vivo performance than the widely used BCS. DOI: 10.1002/jps.22217 PMID: 20821390 [本文引用:1] BRUNO J A , DOTY B D , GUSTOW E , et al . Method of grinding pharmaceutical substances:US,5518187 [P]. 1996 -02-21. [本文引用:1] MERISKO-LIVERSIDGE E , SARPOTDAR P . Formulation and antitumor activity evaluation of nanocrystalline suspensions of poorly soluble anticancer drugs [J]. Pharm Res, 1996 , 13 ( 2 ): 272 - 278 . PURPOSE: Determine if wet milling technology could be used to formulate water insoluble antitumor agents as stabilized nanocrystalline drug suspensions that retain biological effectiveness following intravenous injection. METHODS: The versatility of the approach is demonstrated by evaluation of four poorly water soluble chemotherapeutic agents that exhibit diverse chemistries and mechanisms of action. The compounds selected were: piposulfan (alkylating agent), etoposide (topoisomerase II inhibitor), camptothecin (topoisomerase I inhibitor) and paclitaxel (antimitotic agent). The agents were wet milled as a 2% w/v solids suspension containing 1% w/v surfactant stabilizer using a low energy ball mill. The size, physical stability and efficacy of the nanocrystalline suspensions were evaluated. RESULTS: The data show the feasibility of formulating poorly water soluble anticancer agents as physically stable aqueous nanocrystalline suspensions. The suspensions are physically stable and efficacious following intravenous injection. CONCLUSIONS: Wet milling technology is a feasible approach for formulating poorly water soluble chemotherapeutic agents that may offer a number of advantages over a more classical approach. DOI: 10.1023/a:1016051316815 PMID: 8932448 [本文引用:1] 杜俊锋 , 涂亮星 , 胡凯莉 , 等 . 葛根素纳米晶的制备工艺及其表征 [J]. 湖南中医药大学学报, 2017 , 48 ( 4 ): 369 - 372 . [本文引用:1] GUO Z , ZHANG M , LI H , et al . Effect of ultrasound on anti-solvent crystallization process [J]. J Crystal Growth, 2005 , 273 ( 3/4 ): 555 - 563 . DOI: 10.1016/j.jcrysgro.2004.09.049 [本文引用:1] 崔福德 , 夏登宁 , 朴洪泽 , 等 . 尼群地平药物结晶的尺寸对生物利用度的影响 [C]. 威海,颗粒学前沿问题研讨会暨全国颗粒制备与处理研讨会, 2009 . [本文引用:1] SAHU B P , DAS M K . Preparation and in vitro/ in vivo evaluation of felodipine nanosuspension [J]. Drug Metab Pharmacokinet, 2014 , 39 ( 3 ): 183 - 193 . [本文引用:1] VALO H , AROLA S , LAAKSONEN P , et al . Drug release from nanoparticles embedded in four different nanofibrillar cellulose aerogels [J]. Eur J Pharm Sci, 2013 , 50 ( 1 ): 69 - 77 . Highly porous nanocellulose aerogels prepared by freeze-drying from Various nanofibrillar cellulose (NFC) hydrogels are introduced as nanoparticle reservoirs for oral drug delivery systems. Here we show that beclomethasone dipropionate (BDP) nanoparticles coated with amphiphilic hydrophobin proteins can be well integrated into the NFC aerogels. NFCs from four different origins are introduced and compared to microcrystalline cellulose (MCC). The nanocellulose aerogel scaffolds made from red pepper (RC) and MCC release the drug immediately, while bacterial cellulose (BC), quince seed (QC) and TEMPO-oxidized birch cellulose-based (TC) aerogels show sustained drug release. Since the release of the drug is controlled by the structure and interactions between the nanoparticles and the cellulose matrix, modulation of the matrix formers enable a control of the drug release rate. These nanocomposite structures can be very useful in many pharmaceutical nanoparticle applications and open up new possibilities as carriers for controlled drug delivery. (C) 2013 Elsevier B.V. DOI: 10.1016/j.ejps.2013.02.023 [本文引用:1] ZHANG J , HUANG Y , LIU D , et al . Preparation of apig-enin nanocrystals using supercritical antisolvent process for dissolution and bioavailability enhancement [J]. Eur J Pharm Sci, 2013 , 48 ( 4/5 ): 740 - 747 . DOI: 10.1016/j.ejps.2012.12.026 [本文引用:1] PELTONEN L , HIRVONEN J . Drug nanocrystals-Versatile option for formulation of poorly soluble materials [J]. Int J Pharm, 2018 , 537 ( 1/2 ): 73 - 83 . DOI: 10.1016/j.ijpharm.2017.12.005 [本文引用:1] MÖSCHWITZER J . Drug nanocrystals in the commercial pharmaceutical development process [J]. Int J Pharm, 2013 , 453 ( 1 ): 142 - 156 . Nanosizing is one of the most important drug delivery platform approaches for the commercial development of poorly soluble drug molecules. The research efforts of many industrial and academic groups have resulted in various particle size reduction techniques. From an industrial point of view, the two most advanced top-down processes used at the commercial scale are wet ball milling and high pressure homogenization. Initial issues such as abrasion, long milling times and other downstream-processing challenges have been solved. With the better understanding of the biopharmaceutical aspects of poorly water-soluble drugs, the in vivo success rate for drug nanocrystals has become more apparent. The clinical effectiveness of nanocrystals is proven by the fact that there are currently six FDA approved nanocrystal products on the market. Alternative approaches such as bottom-up processes or combination technologies have also gained considerable interest. Due to the versatility of nanosizing technology at the milligram scale up to production scale, nanosuspensions are currently used at all stages of commercial drug development, Today, all major pharmaceutical companies have realized the potential of drug nanocrystals and included this universal formulation approach into their decision trees. DOI: 10.1016/j.ijpharm.2012.09.034 PMID: 23000841 [本文引用:1] SHEGOKAR R , MULLER R H . Nanocrystals:industrially feasible multifunctional formulation technology for poorly soluble actives [J]. Int J Pharm, 2010 , 399 ( 1/2 ): 129 - 139 . DOI: 10.1016/j.ijpharm.2010.07.044 [本文引用:1] TUOMELA A , LIU P , PURANEN J , et al . Brinzolamide nanocrystal formulations for ophthalmic delivery:reduction of elevated intraocular pressure in vivo [J]. Int J Pharm, 2014 , 467 ( 1/2 ): 34 - 41 . DOI: 10.1016/j.ijpharm.2014.03.048 [本文引用:1] RAHIM H , SADIQ A , KHAN S , et al . Aceclofenac nanocrystals with enhanced in vitro , in vivo performance:formulation optimization, characterization, analgesic and acute toxicitystudies [J]. Durg Des Dev Ther, 2017 , 11 : 2443 - 2452 . [本文引用:1] BEIROWSKI J , INGHELBRECHT S , ARIEN A , et al . Freeze-drying of nanosuspensions, 1:freezing rate versus formulation design as critical factors to preserve the original particle size distribution [J]. J Pharm Sci, 2011 , 100 ( 5 ): 1958 - 1968 . It has been recently reported in the literature that using a fast freezing rate during freeze-drying of drug nanosuspensions is beneficial to preserve the original particle size distribution. All freezing rates studied were obtained by utilizing a custom-made apparatus and were then indirectly related to conventional vial freeze-drying. However, a standard freeze-dryer is only capable of achieving moderate freezing rates in the shelf fluid circulation system. Therefore, it was the purpose of the present study to evaluate the possibility to establish a typical freezing protocol applicable to a standard freeze-drying unit in combination with an adequate choice of cryoprotective excipients and steric stabilizers to preserve the original particle size distribution. Six different drug nanosuspensions containing itraconazole as a drug model were studied using freeze-thaw experiments and a full factorial design to reveal major factors for the stabilization of drug nanosuspensions and the corresponding interactions. In contrast to previous reports, the freezing regime showed no significant influence on preserving the original particle size distribution, suggesting that the concentrations of both the steric stabilizer and the cryoprotective agent are optimized. Moreover, it could be pinpointed that the combined effect of steric stabilizer and cryoprotectant clearly contribute to nanoparticle stability. DOI: 10.1002/jps.22425 PMID: 21374626 [本文引用:1] ANNIKA T , JOUNI H , LEENA P . Stabilizing agents for drug nanocrystals:effect on bioavailability [J]. Pharmaceutics, 2016 , 8 ( 2 ): 16 - 34 . DOI: 10.3390/pharmaceutics8020016 [本文引用:1] SHARMA S , VERMA A , PANDEY G , et al . Investigating the role of pluronic-g-cationic polyelectrolyte as functional stabilizer for nanocrystals:Impact on paclitaxel oral bioavailability and tumor growth [J]. Acta Biomater, 2015 , 26 : 169 - 183 . UNLABELLED: Paclitaxel (PTX) is a potent anticancer drug which suffers limitations of extremely low oral bioavailability due to low solubility, rapid metabolism and efflux by P-gp transporters. The main objective of this study was to overcome the limitation of PTX by designing delivery systems that can enhance the absorption using multiple pathways. A novel Pluronic-grafted chitosan (Pl-g-CH) copolymer was developed and employed as a functional stabilizer for nanocrystals (NCs) and hypothesized that it would improve PTX absorption by several mechanisms and pathways. Pl-g-CH was synthesized and characterized using (1)H NMR and then used as a stabilizer during nanocrystal development. To establish our proof of concept the optimized formulation having a particle size 192.7 +/- 9.2 nm and zeta potential (+) 38.8 +/- 3.12 mV was studied extensively on in vitro Caco-2 model. It was observed that nanocrystals rendered higher PTX accumulation inside the cell than Taxol. P-gp inhibitory potential of Pl-g-CH was proved by flow cytometry and fluorescence microscopy where the much enhanced fluorescence intensity of Rhodamine 123 (Rho-123, P-gp substrate) was observed in the presence of Pl-g-CH. In addition, a significant decrease in Trans Epithelial Electrical Resistance (TEER) of Caco-2 cell monolayers was observed with nanocrystals as well as with Taxol (in the presence of free Pl-g-CH compared to only Taxol). This supports the role of the stabilizer in reversible opening of tight junctions between cells which can allow paracellular transport of drug. The in vivo results were in complete corroboration with in vitro results. Nanocrystals resulted in much enhanced absorption with 12.6-fold improvement in relative bioavailability to that of Taxol. Concomitantly efficacy data in B16 F10 murine melanoma model also showed a significant reduction in tumor growth with nanocrystals compared to Taxol and control. Based on the results it can be suggested that nanocrystals with functional stabilizers can be a promising approach for the oral delivery of anticancer drugs which are P-gp substrates STATEMENT OF SIGNIFICANCE: Nanocrystals are currently one of the most explored novel drug delivery systems especially for oral delivery of drugs because of ease in synthesis and high drug loading. But their use is still limited for oral delivery of anticancer drugs which are P-gp substrates. This particular study aims at widening the scope of nanocrystals by using a functional stabilizer which participates in enhancing the oral absorption of anticancer drugs and controlling the tumor growth. DOI: 10.1016/j.actbio.2015.08.005 PMID: 26265061 [本文引用:1] 岳鹏飞 , 刘阳 , 谢锦 , 等 . 药物纳米晶体制备技术30年发展回顾与展望 [J]. 药学学报, 2018 , 53 ( 4 ): 529 - 537 . [本文引用:1] BITTERLICH A , LAABS C , KRAUTSTRUNK I , et al . Process parameter dependent growth phenomena of naproxen nanosuspension manufactured by wet media milling [J]. Eur J Pharm Biopharm, 2015 , 92 : 171 - 179 . The production of nanosuspensions has proved to be an effective method for overcoming bioavailability challenges of poorly water soluble drugs. Wet milling in stirred media mills and planetary ball mills has become an established top-down-method for producing such drug nanosuspensions. The quality of the resulting nanosuspension is determined by the stability against agglomeration on the one hand, and the process parameters of the mill on the other hand. In order to understand the occurring dependencies, a detailed screening study, not only on adequate stabilizers, but also on their optimum concentration was carried out for the active pharmaceutical ingredient (API) naproxen in a planetary ball mill. The type and concentration of the stabilizer had a pronounced influence on the minimum particle size obtained. With the best formulation the influence of the relevant process parameters on product quality was investigated to determine the grinding limit of naproxen. Besides the well known phenomenon of particle agglomeration, actual naproxen crystal growth and morphology alterations occurred during the process which has not been observed before. It was shown that, by adjusting the process parameters, those effects could be reduced or eliminated. Thus, besides real grinding and agglomeration a process parameter dependent ripening of the naproxen particles was identified to be a concurrent effect during the naproxen fine grinding process. DOI: 10.1016/j.ejpb.2015.02.031 PMID: 25766272 [本文引用:1] XIONG R L , LU W G , LI J , et al . Preparation and char-acterization of intravenously injectable nimodipinena nosuspension [J]. Int J Pharm, 2008 , 350 ( 1/2 ): 338 - 343 . DOI: 10.1016/j.ijpharm.2007.08.036 [本文引用:1] XIA D , QUAN P , PIAO H , et al . Preparation of stable nitrendinine nanosuspensions using the precipitation-ultrasonication method for enhancement of dissolution and oral bioavailability [J]. Eur J Pharm Sci, 2010 , 40 ( 4 ): 325 - 334 . The aim of this study was to prepare and characterize nitrendipine nanosuspensions to enhance the dissolution rate and oral bioavailability of this drug. Nanosuspensions were prepared by the precipitation–ultrasonication method. The effects of five important process parameters, i.e. the concentration of PVA in the anti-solvent, the concentration of nitrendipine in the organic phase, the precipitation temperature, the power input and the time length of ultrasonication on the particle size of nanosuspensions were investigated systematically, and the optimal values were 0.15%, 30 mg/ml, below 3 °C, 400 W and 15 min, respectively. The particle size and zeta potential of nanocrystals were 209 nm (±9 nm) and −13.9 mV (±1.9 mV), respectively. The morphology of nanocrystals was found to be flaky in shape by scanning electron microscopy (SEM) observation. The X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) analysis indicated that there was no substantial crystalline change in the nanocrystals compared with raw crystals. The in vitro dissolution rate of nitrendipine was significantly increased by reducing the particle size. The in vivo test demonstrated that the C _max and AUC _0→12 values of nanosuspension in rats were approximately 6.1-fold and 5.0-fold greater than that of commercial tablets, respectively. DOI: 10.1016/j.ejps.2010.04.006 [本文引用:1] PAWARV K , SINGH Y , MEHER J G , et al . Engineered nanocrystal technology: in-vivo fate, targeting and applications in drug delievery [J]. J Controlled Release, 2014 , 183 : 51 - 66 . DOI: 10.1016/j.jconrel.2014.03.030 [本文引用:1] VOGT F G , WILLIAMS G R . Analysis of a nanocrystalline polymer dispersion of ebselen using solid-state NMR, Raman microscopy,and powder X-ray diffraction [J]. Pharm Res, 2012 , 29 ( 7 ): 1866 - 1881 . PURPOSE: Nanocrystalline drug-polymer dispersions are of significant interest in pharmaceutical delivery. The purpose of this work is to demonstrate the applicability of methods based on two-dimensional (2D) and multinuclear solid-state NMR (SSNMR) to a novel nanocrystalline pharmaceutical dispersion of ebselen with polyvinylpyrrolidone-vinyl acetate (PVP-VA), after initial characterization with other techniques. METHODS: A nanocrystalline dispersion of ebselen with PVP-VA was prepared and characterized by powder X-ray diffraction (PXRD), confocal Raman microscopy and mapping, and differential scanning calorimetry (DSC), and then subjected to detailed 1D and 2D SSNMR analysis involving (1)H, (1)(3)C, and (7)(7)Se isotopes and (1)H spin diffusion. RESULTS: PXRD was used to show that dispersion contains nanocrystalline ebselen in the 35-60 nm size range. Confocal Raman microscopy and spectral mapping were able to detect regions where short-range interactions may occur between ebselen and PVP-VA. Spin diffusion effects were analyzed using 2D SSNMR experiments and are able to directly detect interactions between ebselen and the surrounding PVP-VA. CONCLUSIONS: The methods used here, particularly the 2D SSNMR methods based on spin diffusion, provided detailed structural information about a nanocrystalline polymer dispersion of ebselen, and should be useful in other studies of these types of materials. DOI: 10.1007/s11095-012-0713-9 PMID: 22367510 [本文引用:1] DE WAARD H , HINRICHS W L , FRIJLINK H W . A novel bottom-up process to produce drug nanocrystals:controlled crystallization during freeze-drying [J]. J Control Release, 2008 , 128 ( 2 ): 179 - 183 . To improve the dissolution behavior of lipophilic drugs, a novel bottom-up process based upon freeze drying which allows for the production of nanocrystalline particles was developed: DOI: 10.1016/j.jconrel.2008.03.002 PMID: 18423767 [本文引用:1] MUHAMMAD S A , LANGRISH T , TANG P , et al . A novel method for the production of crystalline micronised particles [J]. Int J Pharm, 2010 , 388 ( 1/2 ): 114 - 122 . DOI: 10.1016/j.ijpharm.2009.12.047 [本文引用:1] 张智亮 , 陈艳雅 , 乐园 , 等 . 超细药物晶体颗粒的制备及其溶出性能 [J]. 高校化学工程学报, 2011 , 25 ( 4 ): 656 - 661 . [本文引用:1] 张智亮 , 乐园 , 王洁欣 , 等 . 超细药物晶体颗粒的制备及其溶出性能的研究 [C]. 长沙,全国化学工程与生物化工年会, 2010 . [本文引用:1] VUDDANDA P R , MONTENEGRO-NICOLINI M , MORALES J O , et al . Effect of surfactants and drug load on physico-mechanical and dissolution properties of nanocrystalline tadalafil-loaded oral films [J]. Eur J Pharm Sci, 2017 , 109 : 372 - 380 . The aim of the present work was to prepare tadalafil (TDF) nanocrystals-loaded oral polymeric films (OFs) and investigate the effect of hydrophilic surfactants and drug loads on the physico-mechanical and dissolution properties. The nanosuspensions of TDF were prepared by high shear homogenization. HPMC based placebo casting film gel was prepared and mixed with TDF nanosuspensions. Films were casted using an automated film applicator and dried at 60 degrees C for 45min. Particle size (PS), polydispersity index (PDI), and zeta potential (ZP) of TDF nanosuspensions were measured in a Zetasizer. The films were characterized using SEM, AFM, DSC, TGA and PXRD. The mechanical properties and in vitro drug release were determined using standard methods. TDF existed in crystalline form and the particles remained in the nano-range in redispersed films. TDF nanocrystals were embedded in the polymeric matrix and the drug loaded films were rough on the surface. Mechanical properties of the films varied with changes in drug load and surfactant. Significant changes in the disintegration times were noticed in films containing surfactants compared to surfactant-free films. About 80% of the drug release was observed between 3 and 30min. TPGS showed better TDF release from the films at different drug loads. CHEMICAL COMPOUNDS: Hydroxy propyl methyl cellulose (PubChem CID: 57503849); Glycerol (PubChem CID: 753); Pluronic F-68 (PubChem CID: 24751); Vitamin E TPGS (PubChem CID: 71406). DOI: 10.1016/j.ejps.2017.08.019 PMID: 28823854 [本文引用:1] CIPOLLA D , WU H , EASTMAN S , et al . Tuning ciprofloxacin release profiles from liposomally encapsulated nanocrystalline drug [J]. Pharm Res, 2016 , 33 ( 11 ): 2748 - 2762 . PURPOSE: In order to attenuate the drug release rate, a single freeze-thaw step was previously shown to convert encapsulated drug into a single nanocrystal within each liposome vesicle. The goal of this study was to alter the nanocrystalline character, and thus the drug encapsulation state and release profile, by addition of surfactant prior to freeze-thaw. METHODS: A liposomal ciprofloxacin (CFI) formulation was modified by the addition of surfactant and frozen. After thawing, these formulations were characterized in terms of drug encapsulation by centrifugation-filtration, liposome structure by cryo-TEM imaging, vesicle size by dynamic light scattering, and in vitro release (IVR) performance. RESULTS: The addition of increasing levels of polysorbate 20 (0.05 to 0.4%) or Brij 30 (0.05 to 0.3%) to the CFI preparations followed by subsequent freeze-thaw, resulted in a greater proportion of vesicles without drug nanocrystals and reduced the extent of growth of the nanocrystals thus leading to modified release rates including an increase in the ratio of non-encapsulated to sustained release of drug. CONCLUSIONS: This study provides another lever to achieve the desired release rate profile from a liposomal formulation by addition of surfactant and subsequent freeze-thaw, and thus may provide a personalized approach to treating patients. DOI: 10.1007/s11095-016-2002-5 PMID: 27439506 [本文引用:1] JACKSON J K , LETCHFORD K , WASSERMAN B Z , et al . The use of nanocrystalline cellulose for the binding and controlled release of drugs [J]. Int J Nanomedicine, 2011 , 6 : 321 - 330 . The objective of this work was to investigate the use of nanocrystalline cellulose (NCC) as a drug delivery excipient. NCC crystallites, prepared by an acid hydrolysis method, were shown to have nanoscopic dimensions and exhibit a high degree of crystallinity. These crystallites bound significant quantities of the water soluble, ionizable drugs tetratcycline and doxorubicin, which were released rapidly over a 1-day period. Cetyl trimethylammonium bromide (CTAB) was bound to the surface of NCC and increased the zeta potential in a concentration-dependent manner from -55 to 0 mV. NCC crystallites with CTAB-modified surfaces bound significant quantities of the hydrophobic anticancer drugs docetaxel, paclitaxel, and etoposide. These drugs were released in a controlled manner over a 2-day period. The NCC-CTAB complexes were found to bind to KU-7 cells, and evidence of cellular uptake was observed. DOI: 10.2147/IJN.S16749 PMID: 21383857 [本文引用:1] PODCZECK F , KNIGHT P E , NEWTON J M . The evaluation of modified microcrystalline cellulose for the preparation of pellets with high drug loading by extrusion/spheronization [J]. Int J Pharm, 2008 , 350 ( 1/2 ): 145 - 154 . DOI: 10.1016/j.ijpharm.2007.08.040 [本文引用:1] WATANABE Y , MUKAI B , KAWAMURA K , et al . Preparation and evaluation of press-coated aminophylline tablet using crystalline cellulose and polyethylene glycol in the outer shell for timed-release dosage forms [J]. Yakuga Zasshi, 2002 , 122 ( 2 ): 157 - 162 . DOI: 10.1248/yakushi.122.157 [本文引用:1] JAVADZADEH Y , SHARIATI H , MOVAHHED-DANESH E , et al . Effect of some commercial grades of microcrystalline cellulose on flowability, compressibility, and dissolution profile of piroxicamliquisolid compacts [J]. Drug Dev Ind Pharm, 2009 , 35 ( 2 ): 243 - 251 . The technique of liquisolid compacts is a promising method toward enhancing the dissolution of poorly soluble drugs. Lower flowability and compressibility is one of the limitations of this technique. The evaluation of effects of different grades of microcrystalline cellulose (MCC) on flowability, compressibility, and dissolution of liquisolid systems were the aims of this study. For this means, several formulations were prepared using various grades of MCC as carrier. Propylene glycol (PG), silica, and sodium starch glycolate were used as nonvolatile solvent, coating material, and disintegrant, respectively. Then flowability, friability hardness, and dissolution rate of prepared formulations were studied. The effect of tablet aging on mentioned properties was also investigated. The results showed that among the evaluated different grades of MCC, compacts containing MCC PH 101 and 102 showed better dissolution profiles. Harder compacts were obtained using MCC PH 101 and 200 as carriers. Better flowability was observed in compacts containing MCC PH 101. Also, these compacts demonstrated acceptable friability. Aging had no effect on hardness and dissolution profile of liquisolid tablets. It could be concluded that MCC PH 101 is a suitable carrier for preparing liquisolid systems for having acceptable flowability, friability, hardness, and dissolution profile. DOI: 10.1080/03639040802277672 PMID: 18785038 [本文引用:1] KNIGHT P E , PODCZECK F , NEWTON J M . The rheolo-gical properties of modified microcrystalline cellulose containing high levels of model drugs [J]. Pharm Sci, 2009 , 98 ( 6 ): 2160 - 2169 . DOI: 10.1002/jps.21587 [本文引用:1] PANDEY G , MITTAPELLY N , BANALA V T , et al . Multifunctional glycoconjugate assisted nanocrystalline drug delivery for tumor targeting and permeabilization of lysosomal-mitochondrial membrane [J]. ACS Appl Mater Interfaces, 2018 , 10 ( 20 ): 16964 - 16976 . Nanotechnology has emerged as the most successful strategy for targeting drug payloads to tumors with the potential to overcome the problems of low concentration at the target site, nonspecific distribution, and untoward toxicities. Here, we synthesized a novel polymeric conjugate comprising chondroitin sulfate A and polyethylene glycol using carbodiimide chemistry. We further employed this glycoconjugate possessing the propensity to provide stability, stealth effects, and tumor targeting via CD44 receptors, all in one, to develop a nanocrystalline system of docetaxel (DTX@CSA-NCs) with size < 200 nm, negative zeta potential, and 98% drug content. Taking advantage of the enhanced permeability and retention effect coupled with receptor mediated endocytosis, the DTX@CSA-NCs cross the peripheral tumor barrier and penetrate deeper into the cells of tumor mass. In MDA-MB-231 cells, this enhanced cellular uptake was observed to exhibit a higher degree of cytotoxicity and arrest in the G2 phase in a time dependent fashion. Acting via a mitochondrial-lysosomotropic pathway, DTX@CSA-NCs disrupted the membrane potential and integrity and outperformed the clinically used formulation. Upon intravenous administration, the DTX@CSA-NCs showed better pharmacokinetic profile and excellent 4T1 induced tumor inhibition with significantly less off target toxicity. Thus, this glycoconjugate stabilized nanocrystalline formulation has the potential to take nano-oncology a step forward. DOI: 10.1021/acsami.7b18699 PMID: 29726253 [本文引用:1] XU H , TIAN Y , YUAN X , et al . The role of CD44 in epithelial-mesenchymal transition and cancer development [J]. Once Tanets Therapy, 2015 , 8 : 3783 - 3792 . [本文引用:1] BASAKRAN N S . CD44 as a potential diagnostic tumor marker [J]. Saudi Med J, 2015 , 36 ( 3 ): 273 - 279 . CD44 is a cellular protein that has been intensively studied in relation to carcinogenesis over the last decade. It is altered during inflammatory responses and cellular malfunctioning during tumor progression. Tumors of epithelial origin express CD44 in multiple isoforms called variants; some isoforms are related to specific cancer cells. An increase of CD44 specific isoforms is detected in certain leukemic proliferations. Most published data indicates a partial involvement of CD44 in cancer cells, either in invasiveness or self-renewability. However, there is still uncertainty regarding the exact mechanism by which CD44 participates in growth of cancer or the inflammatory response. This review focuses on CD44 prevalence in cancer cell. It considers tumorigenic behavior of cells that highly express CD44 as an early marker for neoplastic stem cell proliferation. We will discuss multiple examples of tumor in this paper, with an emphasis of 2 solid tumors; namely, breast and colon cancer. DOI: 10.15537/smj.2015.3.9622 PMID: 25737167 [本文引用:1] HUANG W Y , LIN J N , HSIEH J T , et al . Nanoparticle targeting CD44-positive cancer cells for site-specific drug delivery in prostate cancer therapy [J]. ACS Applied Materials & Interfaces, 2016 , 8 ( 45 ): 30722 - 30734 . Prostate cancer is one of the leading causes of cancer death in adult men and is a multistage disease with therapeutic challenges of local recurrent advanced tumors and distant metastatic disease. CD44 is a multifunctional and multistructural cell surface glycoprotein that is involved in cell-cell interactions, cell proliferation, and cell migration. In the study, we produced negatively charged and biocompatible hyaluronic acid-based nanoparticles as a therapeutic system for targeting CD44-positive cancer cells. Subsequently, we confirmed the delivery of bioactive epigallocatechin-3-gallate and site-specific inhibition of prostate tumor growth. In this study, hyaluronic acid-based nanoparticles successfully encapsulated epigallocatechin-3-gallate and were efficiently internalized into cancer cells via CD44 ligand receptor recognition, induced cell cycle arrest at G2/M phase, and inhibited prostate cancer cell growth. Furthermore, in vivo assays indicated that these nanoparticles specifically bind CD44 receptors and increase apoptosis of cancer cells, leading to significant decreases in prostate tumor activity and tumor tissue inflammation. DOI: 10.1021/acsami.6b10029 PMID: 27786455 [本文引用:1] LIU H , WEBSTER T J . Ceramic/polymer nanocomposites with tunable drug delivery capability at specific disease sites [J]. J Biomed Mat Res Part A, 2010 , 93A ( 3 ): 1180 - 1192 . [本文引用:1]