Targeted Drug Delivery Systems towards Cancer Therapy

Advances in nanotechnology, biotechnology, materials science and pharmaceutical engineering have contributed a lot to novel targeted drug delivery systems that may bring new hope to cancer patients. Here, we propose some strategies of targeting for the delivery of anti-cancer drug and gene. First, we developed a novel thermal targeting anti-cancer drug carrier: thermosensitive copolymers conjugated albumin nanospheres. Biodegradable albumin nanospheres with Rose Bengal (model drug) inside were prepared by ultrasonic emulsification combined with chemical cross-linking by glutaraldehyde. Then, the novel thermal targeting anti-cancer drug carrier was developed by conjugating the thermosensitive copolymers onto the surface of albumin nanospheres.[1] Furthermore, we also prepared hydrophilic albumin nanospheres by desolvation technique and entrapped adriamycin (anti-cancer drug) into albumin nanospheres for in vitro release studies. Albumin nanospheres were found to show autofluorescent property. Thermosensitive copolymers were conjugated onto albumin nanospheres with different conjugation amounts (hairy density) and molecular weights of copolymers (hairy length), and the effect of hairy density and hairy length on drug release was studied. The thermal targeting property of the nanoparticles was tested in cancer cells.[2] In addition, for improved drug targeting of ovarian cancer, brain cancer, kidney cancer, breast cancer, lung cancer, cervical cancer and nasopharyngeal cancer, we designed and developed an actively targetable drug delivery system: folic acid-conjugated albumin nanospheres (FA-AN). The nanospheres were prepared by conjugating folic acid onto the surface of albumin nanospheres using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as a catalyst. The obtained results indicated that FA-AN may be used as a promising actively targetable drug delivery system to improve drug targeting to the above cancer cells.[3] Moreover, for the treatment of liver cancer, we developed another novel actively targetable drug delivery system: galactosamine-conjugated albumin nanoparticles (GAL-AN), which were prepared by conjugating galactosamine onto the surface of albumin nanoparticles. The obtained results reflected that GAL-AN can be used as a promising actively targetable drug delivery system for the treatment of liver cancer.[4] Finally, we developed a series of synthetic gene delivery vectors, which can rapidly and efficiently transfect cells with low or no toxic effect. For example, we synthesized and characterized a series of thermosensitive cationic polymers with low positive charge, and applied them as gene delivery vectors. The concept of using low-positively-charged thermosensitive polymers as gene delivery vectors is innovative and original without any corresponding report.[5] We developed a novel ampholytical chitosan derivative Nimidazolyl-O-carboxymethyl chitosan and used for high performance gene delivery. The cell transfection results with HEK293T cells demonstrate the high transfection efficiency, which is dependent on the degree of imidazolyl substitution.[6] We also explored a chitosan supported imidazole Schiff-base (CISB) as the vector for high performance gene delivery. Introducing the imidazole Schiff-base to the branch of chitosan could improve its water solubility and gene binding ability under physiological conditions, and thus significantly enhance gene delivery capability due to the formation of Schiff-bases (azomethines) and the substitution of imidazole functional groups along chitosan backbones. A transfection efficiency of 70% can be reached after systematically optimizing cell transfection conditions

新型热靶向型纳米药物输送系统的制备及其应用研究

针对现有肿瘤靶向型纳米药物输送系统存在载体不稳定、或聚集于癌组织和细胞后药物释放慢等问题，本论文设计了一种新型热靶向型纳米药物输送系统，即用亲水性白蛋白纳米球包埋抗癌药物、并在其表面共价偶联热敏型高分子。该新型热靶向型纳米药物输送系统聚集于温度较高的癌组织和细胞后，热敏型高分子会收缩，使高分子链间的间隙增大，从而使可生物降解的白蛋白纳米球更容易被蛋白酶攻击并降解，加快药物在癌组织处的释放速度。 本论文分为五个部分。第一部分是热敏型高分子的合成与表征。通过改变异丙基丙烯酰胺（NIPAM）的体积分数γ，采用自由基聚合法合成了聚N-异丙基丙烯酰胺-甲基丙烯酸（2-羟基乙基）酯共聚物（PNIPAM-HEMA）、聚N-异丙基丙烯酰胺-丙烯酸共聚物（PNIPAM-AAc）、聚N-异丙基丙烯酰胺-丙烯酰胺共聚物（PNIPAM-AAm）和聚N-异丙基丙烯酰胺-N,N-二甲基丙稀酰胺共聚物（PNIPAM-DMAA），发现PNIPAM-AAm和PNIPAM-DMAA的浊点温度（Tcp）随着（1-γ）的升高而升高、PNIPAM-HEMA反之、PNIPAM-AAc的Tcp则基本不随（1-γ）的改变而改变，并且这四种共聚物的倒数浊点温度（=1/kBTcp）与（1-γ）线性相关，从而找到了一种控制该类热敏型高分子Tcp的方法。 第二部分是超声乳化法制备白蛋白纳米球（AN），得到了粒径小于200nm、且粒径分布较窄的AN；采用模型药物玫瑰红（RB）初步研究了AN在有酶或无酶情况下的药物释放行为，发现了AN在无酶时的药物释放很慢、而在有酶时的药物释放明显变快。然而，存在着AN在水溶液中分散性不够好的问题。 第三部分是热敏型高分子与白蛋白纳米球的偶联。通过自由基聚合法合成了聚N-异丙基丙烯酰胺-丙烯酰胺-丙烯胺共聚物（PNIPAM-AAm-AA），依靠AA的氨基与AN上的羧基反应，实现了热敏型高分子与AN的偶联，得到了热敏型白蛋白纳米球（PAN）。水力学粒径测量结果表明所制PAN具有较好的热敏性能。然而，由于PNIPAM-AAm-AA末端氨基含量较低，AN表面热敏型高分子的偶联密度较低。 第四部分采用脱溶剂技术解决了AN在水溶液中的分散性不好的问题（第二部分存在的问题）；发现了AN的粒径与牛血清白蛋白（BSA）的浓度成线性关系，找到了控制AN粒径的方法；还发现AN具有自发荧光现象，为白蛋白纳米球的体内示踪提供了一条捷径。 第五部分通过提高PNIPAM-AAm-AA末端氨基含量，提高了AN表面热敏型高分子的偶联密度，制备了不同偶联密度和偶联长度的PAN，并采用抗癌药物阿霉素（ADR）研究了其药物释放行为，解决了第三部分存在的问题；在胰蛋白酶水溶液中，PAN的药物释放速率随着偶联密度或偶联长度的增加而变慢，这是由于空间位阻导致PAN的降解变慢的缘故；温度高于PNIPAM-AAm-AA的Tcp时，PAN的药物释放变快，这是由于高温时PAN表面的热敏型高分子的收缩导致了高分子链间的间隙变大，可克服现有肿瘤靶向型纳米药物输送系统聚集于癌组织和细胞后药物释放慢的缺点；PAN在温度高于PNIPAM-AAm-AA的Tcp时能够靶向作用于癌细胞，而在温度低于Tcp时却不能，这确认了PAN的热靶向性能。 因此，本论文所制新型热靶向型纳米药物输送系统能够靶向经过局部温热疗法加热过的肿瘤组织和细胞，并且在聚集于癌组织和细胞后的药物释放变快，同时，由于其在体温时为亲水性，可较长时间地在血液内循环

Gadolinium oxide nanocrystal-based autofluorescent composite nanoparticles as T1-weighted contrast agents for early diagnosis of cancer

Early diagnosis of cancer greatly increases the chances of a radical resection. The sensitivity of magnetic resonance imaging (MRI) techniques for detecting early tumor can be increased with the assistance of a positive MRI contrast agent. However, the traditional positive MRI contrast agents, such as Gd-chelates and Gd-based inorganic nanoparticles, are often limited by the cytotoxicity and low specificity. Here, we propose a new design of MRI contrast agent based on gadolinium oxide nanocrystals (GON) for targeted imaging and cancer early diagnosis with good biocompatibility. The GON was prepared using a polyol method and then encapsulated into albumin nanoparticles (AN), which are cross-linked with glutaraldehyde and found to exhibit bright and stable autofluorescence without conjugation to any fluorescent agent. After that, the targeted molecule folic acid (FA) was conjugated onto the surface of GON-loaded AN (GON-AN) to construct GON-AN-FA composite. As-prepared nanoparticles are biocompatible and well stable in serum. The results of MRI relaxation studies show that the longitudinal relaxivity (r1) of GON-AN (11.6 mM-1 s-1) and GON-AN-FA (10.8 mM-1 s-1) is much larger than that of traditional positive MRI contrast agents, such as Magnevist (4.7 mM-1 s-1). The results of cell viability assays indicate that GON-AN and GON-AN-FA are almost non-cytotoxic. Furthermore, the specificity of GON-AN and GON-AN-FA were evaluated with two kinds of cancer cells which overexpress folate receptor alpha (FRα). The results reinforce that the autofluorescent GON-AN-FA is targetable to cancer cells via recognition of ligand FA and receptor FRα. Therefore, our autofluorescent GON-AN-FA possessing large longitudinal relaxivity and good biocompatibility represents a significant advance for the targeted imaging and early diagnosis of cancer

Biocompatible composite nanoparticles with large longitudinal relaxivity for targeted imaging and early diagnosis of cancer

Early diagnosis of cancer greatly increases the chances of a radical resection. The sensitivity of magnetic resonance imaging (MRI) techniques for detecting early tumor can be increased with the assistance of a positive MRI contrast agent. However, the traditional positive MRI contrast agents, such as Gd-chelates and Gd-based inorganic nanoparticles, are often limited by the cytotoxicity and low specificity. Here, a new design of MRI contrast agent based on gadolinium oxide nanocrystals (GON) for cancer early diagnosis with biocompatible and targeted imaging is proposed. The GON was prepared using a polyol method and then encapsulated into albumin nanoparticles (AN), which are cross-linked with glutaraldehyde and found to exhibit bright and stable autofluorescence without conjugation to any fluorescent agent. After that, the targeted molecule folic acid (FA) was conjugated onto the surface of GON-loaded AN (GON-AN) to construct GON-AN-FA composite. As-prepared nanoparticles are biocompatible and well stable in serum. The results of MRI relaxation studies show that the longitudinal relaxivity (r1) of GON-AN (11.6 mM-1 s-1) and GON-AN-FA (10.8 mM-1 s-1) is much larger than that of traditional positive MRI contrast agents, such as Magnevist (4.7 mM-1 s-1). The results of cell viability assays indicate that GON-AN and GON-AN-FA are almost non-cytotoxic. Furthermore, the specificity of GON-AN and GON-AN-FA were evaluated with two kinds of cancer cells which overexpress folate receptor alpha (FRα). The results reinforce that the autofluorescent GON-AN-FA is specifically-targetable to cancer cells via recognition of ligand FA and receptor FRα. Therefore, this autofluorescent GON-AN-FA possessing large longitudinal relaxivity, biocompatible and selective targeting capability represents a significant advance for the early diagnosis of cancer

Biocompatible composite nanoparticles with large longitudinal relaxivity for targeted imaging and early diagnosis of cancer

Early diagnosis of cancer greatly increases the chances of successful treatment by radical resection. The sensitivity of magnetic resonance imaging (MRI) techniques for detecting early stage tumors can be increased with the assistance of a positive MRI contrast agent. However, the traditional positive MRI contrast agents, such as Gd-chelates and Gd-based inorganic nanoparticles, are often limited by their cytotoxicity and low specificity. Here, we propose a new design of MRI contrast agent based on gadolinium oxide nanocrystals (GON) for targeted imaging and cancer early diagnosis with good biocompatibility. The GON were prepared using a polyol method and then encapsulated into albumin nanoparticles (AN), which were cross-linked with glutaraldehyde and found to exhibit bright and stable autofluorescence without conjugation to any fluorescent agent. After that, a target molecule, folic acid (FA), was conjugated onto the surface of the GON-loaded AN (GON-AN) to construct a GON-AN–FA composite. The as-prepared nanoparticles are biocompatible and stable in serum. The results of MRI relaxation studies show that the longitudinal relaxivities (r1) of GON-AN (11.6 mM 1 s 1) and GON-AN–FA (10.8 mM 1 s 1) are much larger than those of traditional positive MRI contrast agents, such as Magnevist (3.8 mM 1 s 1). The results of cell viability assays indicate that GON-AN and GON-AN–FA are almost noncytotoxic. Furthermore, the specificities of GON-AN and GON-AN–FA were evaluated with two kinds of cancer cells which overexpress folate receptor alpha (FRa). The results reinforce that the autofluorescent GON-AN–FA is able to target cancer cells via recognition of the ligand FA and the receptor FRa. Therefore, our autofluorescent GON-AN–FA possessing a large longitudinal relaxivity and good biocompatibility represents a significant advance for the targeted imaging and early diagnosis of cancer

肿瘤早期诊断用隐形造影材料及其制备方法

本发明公开了一种肿瘤早期诊断用隐形造影材料及其制备方法，采用可生物降解纳米球包埋医学造影剂、在纳米球的表面偶联与肿瘤细胞有特异性相互作用的靶分子、并接枝pH敏感型高分子。纳米球表面的靶分子在正常生理条件下隐藏在pH敏感型高分子之中，不能与正常细胞的非特异性抗原或受体发生相互作用，故该隐形造影材料不能被正常细胞非特异性摄取；而纳米球表面的靶分子在肿瘤组织环境下由于高分子收缩而暴露出来，与肿瘤细胞表面的抗原或受体发生特异性相互作用，从而实现将隐形造影材料高精准地靶向输送至肿瘤部位，降低医学造影剂的用药剂量、毒副作用和成本

一种检测二价镍离子的方法

本发明公开了一种检测二价镍离子的方法。本发明提供的通过含二肟类化合物修饰吐温保护的银纳米粒子测定水溶液中二价镍离子的方法，包括以下步骤：(a)提供一种含二肟类化合物修饰吐温保护的银纳米粒子检测液；(b)向所述检测液中加入待测样本，形成检测混合液；(c)观察或测量所述检测混合液的颜色和/或紫外可见光光谱，并与对照相比或与标准图谱进行比较，从而得出待测样本是否存在二价镍离子和/或二价镍离子的浓度的测定结果。本发明方法特异性强，灵敏度高，且操作简便、适用对象范围广