以叶酸受体为靶向的阳离子脂质体的制备与性质考察

为了研制一种能通过叶酸受体途径靶向肿瘤细胞的叶酸受体靶向脂质体，将叶酸(folate，folic acid，F)、 聚乙二醇二胺(polyoxyethylene-bis-amine，NH₂-PEG-NH₂)、 琥珀酸酐(succinic anhydride，SUC)和二硬脂酰磷脂酰乙醇胺(distearoylphosphatidylethanolamine，DSPE)按序共价连接， 并使用薄层色谱和飞行时间质谱确证合成产物为叶酸-聚乙二醇-二硬脂酰磷脂酰乙醇胺(folate-polyethyleneglycol-distearoylphosphatidylethanolamine，F-PEG-DSPE)。膜材选用二棕榈酰磷脂酰胆碱(dipalmitoylphosphatidylcholine，DPPC)， 3β-［N-(N′,N′-二甲基胺乙基)胺基甲酰基］胆固醇(3β-［N(N′,N′-dimethylaminoethane) carbamoyl］ cholesterol，DC-Chol)和F-PEG-DSPE，以10∶10∶0.75(摩尔比)的配比，以荧光素标记的阴离子葡聚糖(dextran fluorescein anionic，DFA)为模型，用薄膜分散法制备含DFA的叶酸受体靶向脂质体，其包封率较高(>55%)、稳定性好，平均粒径为144 nm，体外释放慢。MTT法考察其对细胞的毒性结果表明该阳离子脂质体具有一定的细胞毒性，在低浓度时(0.012 5～0.1 μmol·L^{-1)脂质体的细胞毒性与DC-chol浓度成正比。流式细胞技术检测KB细胞和HepG2细胞对DFA脂质体的摄取，结果表明叶酸受体靶向的长循环阳离子脂质体能提高细胞对脂质体的摄取。该研究为进一步研究叶酸受体靶向阳离子脂质体在肿瘤基因治疗中的应用提供了理论基础。}     

钾通道阻断剂部分抑制三氧化二砷诱导的HeLa细胞死亡

目的研究钾通道阻滞剂对三氧化二砷诱导的HeLa细胞死亡的作用。方法采用MTT法评价HeLa细胞的存活情况，采用膜片钳技术记录HeLa细胞的电压依赖性钾电流。结果As₂O₃(5 μmol·L^-1)孵育24 h引起显著的HeLa细胞死亡，As₂O₃(5 μmol·L^-1)孵育24 h后存活的细胞表现明显的电压依赖性钾电流密度增加。+80 mV电压下，As₂O₃(5 μmol·L^-1)孵育组电流密度(61±18) pA/10 pF(n=8)明显高于对照组(38±10) pA/10 pF(n=8,P<005)。As₂O₃诱导的HeLa细胞死亡可被共同孵育钾通道阻滞剂四氨基吡啶(3 mmol·L^-1)或四乙基铵(5 mmol·L^-1)所部分抑制。3 mmol·L^-1四氨基吡啶或5 mmol·L^-1四乙基铵对HeLa细胞无明显细胞毒作用。结论As₂O₃长期处理增加HeLa细胞的电压依赖性钾电流。As₂O₃诱导的HeLa细胞死亡可被钾通道阻滞剂四氨基吡啶或四乙基铵部分抑制。     

9-硝基喜树碱在Caco-2细胞模型中的体外摄取、转运及外排动力学

目的研究9-硝基喜树碱(9-NC)的细胞摄取、转运及外排特性。方法一种体外培养的人小肠上皮细胞模型Caco-2应用于9-NC的小肠上皮细胞的摄取、跨膜转运及外排动力学研究。评价了时间、温度、pH,P-糖蛋白(P-glycoprotein, P-gp)抑制剂对细胞摄取的影响。采用HPLC测定药物含量。结果9-硝基喜树碱以被动扩散为主要方式被细胞摄取和转运。药物的摄取与时间呈正相关，与温度、pH呈负相关。P-gp抑制剂环孢菌素和维拉帕米增加9-NC细胞摄取(P<0.05)。药物从Basolateral(B,基底面)到Apical(A,肠腔面)的渗透系数P_app大于A到B(2.6-6.9倍)。9-NC外排符合二级外排动力学过程，A侧m₀［(148.0±2.2) pmol·cm^-2］和外排速率(41.1 pmol·cm²·min^-1)高于B侧的m₀［(121±7) pmol·cm^-2(P<0.05)和外排速率(29.2 pmol·cm²·min^-1)(P<0.01)。结论 9-NC是以被动扩散方式为主要方式被小肠上皮细胞摄取和转运，并受到P-糖蛋白强烈的外排作用。     

叶酸偶联的青霉素G酰化酶对叶酸受体阳性肿瘤细胞的靶向作用

目的 研究叶酸偶联的青霉素G酰化酶(F-PGA)对叶酸受体阳性肿瘤细胞的靶向作用.方法 用激光共聚焦显微镜观察宫颈癌HeLa、卵巢癌SKOV3和肺癌A549细胞对F-PGA以及游离叶酸(F-A)的摄取,并进一步用同位素示踪法加以验证和定量检测.结果 F-PGA与F-A相似,均能被叶酸受体阳性的HeLa和SKOV3肿瘤细胞选择性摄取,且有饱和性、可逆性、温度依赖性和高亲和性的特点,但不能被叶酸受体阴性的A549细胞摄取.结论 F-PGA与F-A都是通过叶酸受体介导,从而特异性地靶向于叶酸受体阳性肿瘤细胞的.     

藏红花素联合顺铂对人宫颈癌HeLa细胞协同抑制作用的研究

目的 探索藏红花素联合顺铂对人宫颈癌HeLa细胞的协同抑制作用及相关调控机制。方法 取对数生长期人宫颈癌HeLa细胞,设置空白对照组（DMSO）、藏红花素组（400 μg·mL^-1）、顺铂组（5 μg·mL^-1）、联合组（藏红花素400 μg·mL^-1+顺铂5 μg·mL^-1）。干预48 h后,CCK-8检测HeLa细胞增殖抑制率,采用CompuSyn软件计算藏红花素与顺铂的联合指数（CI）,Annexin V-FITC染色法检测细胞凋亡,流式细胞术检测细胞周期分布,Western blotting检测激活型半胱氨酸天冬氨酸蛋白酶-3（Cleaved Caspase-3）、B细胞淋巴瘤/白血病-2（Bcl-2）、Bcl-2相关X蛋白（Bax）、细胞周期素D1（Cyclin D1）、周期蛋白依赖激酶2（CDK2）的表达。结果 与顺铂组比较,联合组细胞增殖抑制率显著升高（P<0.05）,CI为0.68,具有中度协同效应;细胞凋亡率显著升高（P<0.01）,G₀/G₁期细胞比例显著升高（P<0.05）,而G₂/M期比例显著降低（P<0.01）,Cleaved Caspase-3、Bax蛋白表达水平及Bax/Bcl-2比值均显著升高（P<0.05）,Cyclin D1、CDK2蛋白表达水平显著降低（P<0.01）。与空白对照组比较,藏红花素组G₀/G₁期细胞比例显著升高而G₂/M期比例显著降低（P<0.01）,Cleaved Caspase-3、Bax表达水平及Bax/Bcl-2比值均显著升高（P<0.01）,Cyclin D1、CDK2表达水平显著降低（P<0.05）。结论 藏红花素联合顺铂可协同抑制人宫颈癌HeLa细胞的增殖和生长,其作用机制可能与调控凋亡相关蛋白的表达从而促进细胞凋亡、阻滞细胞周期进程有关。     

3,5-O-二咖啡酰基奎宁酸的制备及其对HeLa细胞的抗增殖活性研究

目的 制备高纯度3，5-O-二咖啡酰基奎宁酸，并评价其对人宫颈癌HeLa细胞的抗增殖活性。方法 采用柱色谱提取法和中压液相色谱法从奇蒿花中分离、纯化得到高纯度的3，5-O-二咖啡酰基奎宁酸。采用MTT法评价该化合物对人宫颈癌HeLa细胞的体外抗增殖活性。结果 柱色谱提取的提取率和中压液相色谱法的回收率分别为99.0%，61.2%，总回收率为54.0%。随着3，5-O-二咖啡酰基奎宁酸浓度升高，HeLa细胞存活率下降，细胞形态损伤增加，受试药物的IC₅₀值为26.5µg·mL^-1。结论 本研究提供了一种简单、高效、节能的3，5-O-二咖啡酰基奎宁酸制备方法。3，5-O-二咖啡酰基奎宁酸对HeLa细胞具有一定的体外抗增殖活性。     

pH响应纳米载药系统DOX@MIL-101(Fe)-NH2/HA的制备及靶向抗肿瘤作用研究

目的 制备透明质酸(hyaluronan acid，HA)修饰的纳米金属有机框架MIL-101(Fe)-NH₂载药系统，并进行体外抗肿瘤活性评价。方法 采用溶剂热法制备MIL-101(Fe)-NH₂，通过物理吸附法制备HA修饰载阿霉素的DOX@MIL-101(Fe)- NH₂/HA(DMNH)。并利用扫描电子显微镜、X射线衍射仪、氮气吸附-脱附法等对所合成材料及载药系统进行表征。采用透析法考察了载药系统的体外释药行为，并利用激光共聚焦显微镜观察HepG2细胞对其摄取情况。结果 MIL-101(Fe)-NH₂形貌为规则的正八面体，比表面积和粒径分别为1 061.45 m²·g^-1和200 nm。载药后DMNH的尺寸均一，比表面积为205.84 m²·g^-1，粒径为300 nm。MIL-101(Fe)-NH₂的最佳载药率为65.3%，根据药物释放曲线，从装有阿霉素的MIL-101(Fe)-NH₂载药体系(DMN)、DMNH中释放阿霉素显示出时间和pH依赖性。细胞摄取试验结果显示DMNH较其他组别可以运输更多的阿霉素进入HepG2细胞。细胞毒性的结果证实在相同的药物浓度下，DMNH表现出更高的肿瘤细胞杀伤效率。结论 本研究制备的DMNH载药系统结构稳定、载药量和释药效率高，同时具有优异的肿瘤细胞靶向性及pH响应释放特性，在抗肿瘤药物靶向传输方面具有应用前景。     

外泌体携载阿霉素递送体系构建及体外抗肿瘤活性评价

目的 制备肝癌细胞Hep1-6外泌体并对化疗药物阿霉素（DOX）进行包载,以期实现对肿瘤细胞更高的靶向活性与杀伤作用。方法 采用梯度离心法对肿瘤细胞Hep1-6来源的外泌体进行制备分离;采用透射电镜技术、表面标记蛋白表征以及纳米颗粒追踪分析技术对外泌体的形态、特征蛋白、粒径分布和浓度进行表征;采用电穿孔方法实现外泌体对DOX的有效包载,制备包载阿霉素外泌体（EXO_DOX）。采用CCK-8法检测EXO_DOX与DOX（0.5、1、2、3、5、10 μg·mL^-1）体外对 Hep1-6细胞增殖的影响,采用激光共聚焦显微镜观察体外 Hep1-6细胞对 EXO_DOX与 DOX（1 μg·mL^-1）的靶向摄取作用。结果 所制备的外泌体具有形态良好 、 粒度均一的特性且具备外泌体特征膜蛋白 CD63、 CD81、 肿瘤易感基因101（TSG101）的表达;在电穿孔条件为150 V和75 μF下外泌体对DOX具备良好的包载特性;相比于单独给药DOX,在同等质量浓度下 EXO_DOX对 Hep1-6细胞增殖抑制作用显著增强（P＜0.05、0.01）,同时肿瘤细胞对 EXO_DOX的摄取更具靶向性。结论 制备的EXO_DOX较DOX具有更强的体外细胞毒活性,EXO_DOX表现出对肿瘤细胞更高的靶向特性。     

银杏叶提取物对低氧复氧、H2O2和谷氨酸损伤时谷氨酸引起的大鼠星形胶质细胞［Ca2+］i变化的影响

目的研究银杏叶提取物对低氧复氧、H₂O₂和L-谷氨酸损伤时谷氨酸升高大鼠星形胶质细胞［Ca²⁺］_i的影响。方法钙荧光探针Fluo-3/AM标记胞浆内游离钙离子，激光扫描共聚焦显微镜测定［Ca²⁺］_i的变化。结果 在低氧复氧、H₂O₂以及高浓度的L-谷氨酸损伤后，外源性谷氨酸（27 μmol·L^-1）均不能引起培养乳大鼠星形胶质细胞正常的［Ca²⁺］_i升高，反而使［Ca²⁺］_i分别降低(3.3±1.6)%，(81±11)%和(81±7)%；损伤前预先给予GbE（10 mg·L^-1）不能明显改善星形胶质细胞的谷氨酸反应，但预先给予GbE（100 mg·L^-1）后，27 μmol·L^-1谷氨酸可使损伤的星形胶质细胞［Ca²⁺］_i分别升高(135±98)%，(117±93)%和(89±36)%。结论低氧复氧、H₂O₂以及高浓度的L-谷氨酸均能损伤星形胶质细胞的谷氨酸反应，影响神经细胞与胶质细胞的双向交流。GbE能明显逆转不同损伤后谷氨酸诱导星形胶质细胞［Ca²⁺］_i的异常变化，使星形胶质细胞在不同损伤时能维持正常功能，该作用可能与GbE的脑保护作用有关。     

松果菊苷抑制卵巢癌SKOV3细胞的增殖、侵袭和干细胞样特性

目的 探讨松果菊苷对卵巢癌SKOV3细胞的作用。方法 选择不同浓度的松果菊苷处理卵巢癌SKOV3细胞,24 h后CCK8检测细胞存活率;选择不同浓度松果菊苷浓度(0,20,40,80μmol·L^-1)进行后续实验,EdU染色检测细胞增殖;Transwell检测细胞侵袭;免疫印迹法检测VEGF、E-cadherin、Vimentin的表达及p38 MAPK的磷酸化;显微观察细胞肿瘤球形态;流式细胞仪检测CD133和CD44的含量。结果 SKOV3细胞的存活率与松果菊苷呈浓度依赖性降低,松果菊苷浓度≥40μmol·L^-1时,SKOV3细胞的存活率较松果菊苷0μmol·L^-1时均明显降低(P<0.05)。与松果菊苷0μmol·L^-1组比较,松果菊苷40μmol·L^-1组和80μmol·L^-1组EdU阳性细胞数和侵袭细胞数均减少(P<0.05);VEGF和Vimentin蛋白表达水平及p38 MAPK磷酸化水平均降低(P<0.05);E-cadherin蛋白表达水平升高(P<0.05);肿瘤干细胞成球直径减小(P<0.05),成球数减少(P<0.05);CD133和CD44表达均降低(P<0.05)。结论 松果菊苷可以抑制卵巢癌SKOV3细胞的增殖、侵袭、干细胞样特性及p38 MAPK的磷酸化。     

叶酸受体阳性肿瘤细胞对Folate-PGA偶联酶的特异性结合

目的考察叶酸受体阳性肿瘤细胞对叶酸偶联的青霉素G酰化酶(Folate-PGA)的特异性结合。方法采用Iodo-gen法标记的125I-Folate-PGA测定叶酸受体表达阳性FR(+)HeLa与SKOV3细胞以及叶酸受体表达阴性FR(-)A549细胞于4℃对Folate-PGA偶联酶的结合。结果125I-Folate-PGA对FR(-)A549无特异性结合;与HeLa和SK-OV3细胞的特异性结合的Kd分别为0.11nmol·L-1和0.25nmol·L-1。结论叶酸偶联的PGA酶对FR(+)肿瘤细胞具有较好的亲和力和靶向性,可用于叶酸导向的酶前体药物疗法的进一步研究。     

Increase of doxorubicin sensitivity for folate receptor positive cells when given as the prodrug N-(phenylacetyl) doxorubicin in combination with folate-conjugated PGA

Folate receptor (FR) has been proposed as a promising target for tumor drug targeting. The aim of this study was to increase the chemo-sensitivity of FR-positive cells to doxorubicin by folate-directed enzyme prodrug therapy (FDEPT). Folate conjugated penicillin-G amidase was prepared and its ability to hydrolyze N-(phenylacetyl) doxorubicin was measured by HPLC. Fluorescence and confocal image analysis revealed that Folate-PGA can be specifically delivered into FR-positive HeLa and SKOV3 tumor cells. In vitro cytotoxity assays, IC50 was reduced with N-(phenylacetyl) doxorubicin versus doxorubicin for HeLa (3.1-fold reduction; p<0.001) and SKOV3 (3.3-fold reduction; p<0.001) when Folate-PGA was specifically bound to the cells. Complete activation was confirmed in HeLa and SKOV3 cells pretreated with free folic acid (1 mM), where the combination of N-(phenylacetyl) doxorubicin with Folate-PGA did not show any significant cell toxicity to the IC50 of doxorubicin. Pharmacokinetic clearance and biodistribution studies in vivo showed that 125I-Folate-PGA was cleared from blood within 24 h and had significantly higher tumor uptake compared to 125I-PGA (p<0.05). These results demonstrate that the FDEPT approach may be a potential promising strategy to improve chemotherapy-resistant cancers therapeutic ratio and warranted future studies.     

A Folate Receptor–Targeted Lipid Nanoparticle Formulation for a Lipophilic Paclitaxel Prodrug

No HeadingPurpose. The anticancer drug paclitaxel has poor aqueous solubility and is difficult to formulate in a lipid-based formulation due to its limited lipid solubility. Paclitaxel-7-carbonyl-cholesterol (Tax-Chol), a prodrug of paclitaxel with increased lipophilicity, was therefore synthesized and evaluated for incorporation into a lipid nanoparticle (LN) formulation, which also contained folate-polyethylene glycol-cholesterol (f-PEG-Chol) as a ligand that targets the tumor marker folate receptor (FR). This novel formulation was designed for prolonged systemic circulation and selective targeting of tumor cells with amplified FR expression.Methods. Tax-Chol was synthesized. FR-targeted LNs, composed of distearoyl phosphatidylcholine (DSPC)/triolein/Chol oleate/PEG-Chol/f-PEG-Chol (40:40:18:2.0:0.5, mole/mole), were then prepared by solvent dilution followed by diafiltration. FR-targeted LNs containing Tax-Chol were then evaluated for cytotoxicity in KB, a human oral carcinoma cell line, and M109, a murine lung carcinoma cell line, both of which are FR(+) and in FR(–) Chinese hamster ovary (CHO) cells. Furthermore, tumor growth inhibition and animal survival in response to treatment with FR-targeted LNs and control formulations were evaluated in BALB/c mice bearing subcutaneously engrafted M109 tumors.Results. The LNs had a mean diameter of 130 nm and Tax-Chol incoporation efficiency of greater than 90% and exhibited excellent colloidal stability. FR-targeted LNs showed greater uptake and cytotoxicity in FR(+) KB and M109 cells than nontargeted LNs. Furthermore, treatment of mice bearing M109 tumors with FR-targeted LNs resulted in significantly greater tumor growth inhibition and animal survival compared to treatment with nontargeted LNs or paclitaxel formulated in Cremophor EL.Conclusions. FR-targeted LNs containing Tax-Chol are a promising novel formulation for the treatment of FR(+) tumors and further preclinical studies are warranted.     

Antitumor Activity of Folate Receptor-Targeted Liposomal Doxorubicin in a KB Oral Carcinoma Murine Xenograft Model

Purpose. The expression of folate receptor (FR) is amplified in many types of human cancers. Previously, FR-targeted liposomal doxorubicin (f-L-DOX) has been shown to exhibit superior and selective cytotoxicity against FR(+) tumor cells in vitro compared to nontargeted liposomal doxorubicin (L-DOX). This study further investigates f-L-DOX for its antitumor efficacy in vivo using a murine tumor xenograft model. Methods. F-L-DOX composed of DSPC/cholesterol/PEG-DSPE/folate-PEG-DSPE (65:31:3.5:0.5, mole/mole) was prepared by polycarbonate membrane extrusion followed by remote loading of DOX. Athymic mice on a folate-free diet were engrafted with FR(+) KB cells. Two weeks later, these mice were treated with f-L-DOX, L-DOX, or free DOX in a series of six injections (given intraperitoneally on every fourth day at 10 mg/kg DOX) and monitored for tumor growth and animal survival. The plasma clearance profiles of the DOX formulations and the effect of dietary folate on plasma folate concentration were also analyzed. Results. Plasma folate level remained in the physiologic range relative to that in humans. F-L-DOX exhibited an extended systemic circulation time similar to that of L-DOX. Mice that received f-L-DOX showed greater tumor growth inhibition and a 31% higher (p < 0.01) increase in lifespan compared to those that received L-DOX. Meanwhile, free DOX given at the same dose resulted in significant toxicity and was less effective in prolonging animal survival. Conclusions. FR-targeted liposomes are a highly efficacious vehicle for in vivo delivery of anticancer agents and have potential application in the treatment of FR(+) solid tumors.     

Folate-modified poly(2-ethyl-2-oxazoline) as hydrophilic corona in polymeric micelles for enhanced intracellular doxorubicin delivery

The transmembrane transport of drug loaded micelles to intracellular compartment is quite crucial for efficient drug delivery. In the current study, we investigated the cellular internalization and anticancer activity of doxorubicin loaded micelles with folate modified stealthy PEOz corona. Folate-decorated micelles incorporating doxorubicin were characterized for particle size, degree of folate decoration, drug loading content and encapsulation efficiency, morphology, and surface charge. The targeting capability and cell viability were assessed using HeLa, KB, A549 and MCF-7/ADR cell lines. In vitro study clearly illustrated the folate receptor (FR) mediated targeting of FA modified micelles to FR-positive human HeLa, KB and MCF-7/ADR cells, while specific delivery to FR-negative A549 cells was not apparently increased at the same experimental conditions. Cytotoxicity assay showed 60% and 58% decrease in IC₅₀ values for HeLa and KB cells, while only a slight decrease for A549 cells, following treatment with folate modified formulations. The enhanced intracellular delivery of FA modified micelles in MCF-7/ADR cells was also observed. In vivo antitumor tests revealed DOX entrapped FA-PEOz-PCL micelles effectively inhibited the tumor growth and reduced the toxicity to mice compared with free DOX. The current study showed that the targeted nano-vector improved cytotoxicity of DOX and suggested that this novel PEOz endowed stealthy micelle system held great promise in tumor targeted therapy.     

Folate-targeted enzyme prodrug cancer therapy utilizing penicillin-V amidase and a doxorubicin prodrug

In antibody-targeted enzyme prodrug therapy, a monoclonal antibody (mAb) covalently linked to an enzyme is commonly exploited to concentrate the enzyme on the tumor cell surface prior to administration of a relatively nontoxic prodrug. The tumor-localized enzyme then converts the prodrug into a cytotoxic agent, which in turn diffuses into the tumor causing localized cell death. In this paper, we have substituted folic acid for the mAb as a mean of delivering an attached enzyme, penicillin-V amidase (PVA), to folate receptor (FR)-positive tumor cells. The enzyme PVA is capable of converting a doxorubicin-N-p-hydroxyphenoxyacetamide prodrug (DPO) into its potent parent drug, doxorubicin. For PVA targeting, each PVA molecule was covalently labeled with three molecules of folic acid via the formation of amide bonds. In vitro binding assays showed that folate-PVA-125I conjugates bind specifically to KB cells (FR-positive tumor cells) but not to A549 cells (FR-negative tumor cells). Moreover, in a series of in vitro cytotoxicity tests, folate-PVA conjugates were found to kill folate receptor positive but not receptor negative cells, and when bound to FR-positive cells, folate-PVA conjugates rendered the DPO prodrug as toxic as free doxorubicin (IC50, approximately 0.6 microM). Finally, preliminary in vivo plasma clearance studies in normal mice revealed that i.v. administered folate-PVA-125I and PVA-125I are both cleared from the blood within a 24 h time period, removing concern that nonspecifically trapped folate-PVA might activate prodrug in nontargeted tissues. In view of the fact that only a small number of folate-PVA molecules are required to mediate killing of target cells in vitro, these data argue that folate-targeted enzyme prodrug therapy should be considered for tumor eradication in vivo.     

Targeted Sialic Acid–Doxorubicin Prodrugs for Intracellular Delivery and Cancer Treatment

Purpose To evaluate a novel targeted anticancer prodrug consisting of several copies of sialic acid (SA, targeting moiety), doxorubicin (DOX), citric acid (multifunctional spacer) and poly(ethylene glycol) (PEG, carrier). Methods α, ω bis carboxyl PEG was covalently conjugated with multiple copies of SA and DOX through a citric acid spacer and characterized by proton nuclear magnetic resonance (¹HNMR), matrix-assisted laser desorption/ionization-time of flight (MALDI/TOF), and high-performance liquid chromatography (HPLC). The molecular models of conjugates were established using ChemDraw software. Stability, spontaneous and esterase-stimulated drug release was analyzed by HPLC. Cellular internalization (fluorescence microscopy) and cytotoxicity [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay] of free DOX and prodrugs were evaluated. Results ¹HNMR, MALDI/TOF, and HPLC showed the formation of the PEG prodrug conjugates. More than 40% of the drug was released from its conjugate in the presence of esterase enzyme, whereas the conjugate was stable at pH 7.4 in the absence of enzyme. Molecular modeling studies showed stable conformations of conjugates. The targeted prodrug conjugates with two copies of SA and DOX showed enhanced cytotoxicity when compared with non-targeted prodrugs and free DOX. Conclusions Targeting of the conjugate to cancer cells by SA with increased copies of targeting moiety and anticancer drug enhanced prodrug uptake by cancer cells and cytotoxicity of the prodrug.     

Doxorubicin-conjugated D-glucosamine- and folate- bi-functionalised InP/ZnS quantum dots for cancer cells imaging and therapy

Nanoscaled quantum dots (QDs), with unique optical properties have been used for the development of theranostics. Here, InP/ZnS QDs were synthesised and functionalised with folate (QD-FA), D-glucosamine (QD-GA) or both (QD-FA-GA). The bi-functionalised QDs were further conjugated with doxorubicin (QD-FA-GA-DOX). Optimum Indium to fatty acid (In:MA) ratio was 1:3.5. Transmission electron microscopy (TEM) micrographs revealed spherical morphology for the QDs (11?nm). Energy-dispersive spectroscopy (EDS) spectrum confirmed the chemical composition of the QDs. MTT analysis in the OVCAR-3 cells treated with bare QDs, QD-FA, QD-GA, QD-FA-GA and QD-FA-GA-DOX (0.2?mg/mL of QDs) after 24?h indicated low toxicity for the bare QDs and functionalised QDs (about 80–90% cell viability). QD-FA-GA-DOX nanoparticles elicited toxicity in the cells. Cellular uptake of the engineered QDs were investigated in both folate receptor (FR)-positive OVCAR-3 cells and FR-negative A549 cells using fluorescence microscopy and FACS flow cytometry. The FA-functionalised QDs showed significantly higher uptake in the FR-positive OVCAR-3 cells, nonetheless the GA-functionalised QDs resulted in an indiscriminate uptake in both cell lines. In conclusion, our findings indicated that DOX-conjugated FA-armed QDs can be used as theranostics for simultaneous imaging and therapy of cancer.     

Selectivity of folate conjugated polymer micelles against different tumor cells

Folate or folic acid has been employed as a targeting moiety of various anticancer agents to increase their cellular uptake within target cells since folate receptors are vastly overexpressed in several human tumors. In this study, a biodegradable polymer poly(d,l-lactide-co-glycolide)-poly(ethylene glycol)-folate (PLGA-PEG-FOL) was used to form micelles for encapsulating anticancer drug doxorubicin (DOX). The drug loading content, encapsulation efficiency and in vitro release were characterized. To evaluate the targeting ability of the folate conjugated micelles, the cytotoxicity and cellular uptake of DOX-loaded micelles on three cancer cell lines with different amount of folate receptors (KB, MATB III, C6) and normal fibroblast cells (CCL-110) were compared. The cytotoxicity of PLGA-PEG-FOL micelles to cancer cells was found to be much higher than that of normal fibroblast cells, demonstrating that the folate conjugated micelles has the ability to selectively target to cancer cells. For normal cells, the cellular uptake of PLGA-PEG-FOL micelles was similar to PLGA-PEG micelles without folate conjugation, and was substantially lower than that of cancer cells. In addition, the cell cycle analysis showed that the apoptotic percentage of normal fibroblasts was substantially lower compared with the cancer cells after exposing to DOX-loaded PLGA-PEG-FOL micelles. An optimal folate amount of approximately 40-65% on the micelles was found to be able to kill cancer cells but, at the same time, to have very low effect to normal cells.     

Folate receptor–targeted quantum dot liposomes as fluorescence probes

In this study, the preparation of the novel imaging agents, folate receptor (FR)–targeted liposomes encapsulating hydrophilic CdTe quantum dots (QDs), and their use as luminescence probes for live cell imaging are reported. Hydrophilic CdTe QDs were directly synthesized in the water phase, and FR-targeted QD liposomes were prepared by hydrating the lipid thin film with CdTe suspension. Formulations were characterized by UV-visible and fluorescent measurements, liposomal particle size, and zeta potential. The targeting and imaging ability of FR-targeted liposomes were investigated against the human uterine cervix cancer cell line (HeLa). Furthermore, the cytotoxicity of QD liposomes was evaluated by HeLa cells incubated with FR-targeted QD liposomes, nontargeted QD liposomes, and free QDs. The results showed that FR-targeted QD liposomes were spherically shaped with high fluorescence yield, excellent photochemical stability, good cancer targeting, and minimal cytotoxicity. The average size of FR-targeted fluorescence liposomes was ~105?nm, and their size distribution was rather narrow. After storage at 4°C for 11 months, QD liposomes maintained similar size and did not show any leakage of QDs. FR-targeted CdTe QD liposomes, which can target tumor cells via FR-mediated endocytosis, would become an attractive probe for tumor cell or tissue imaging for a long-time monitoring.