两种pH敏感的羟丙甲纤维素衍生物的合成及性质比较

 目的制备两种pH敏感的羟丙甲纤维素(HPMC)衍生物,并研究其相关特性,以筛选适宜的十二指肠定位释药包衣材料。方法用偏苯三酸酐和顺丁烯二酸酐对HPMC进行化学修饰,对羟丙甲纤维素偏苯三酸酯(HPMCT)和醋酸羟丙基甲基纤维素顺丁烯二酸酯(HPMCAM)的性质如酸值、pH敏感值、膜透湿性、抗拉强度、玻璃化转变温度进行了初步探讨。并选用盐酸黄连素为模型药物进行包衣片剂的体外释放试验。结果两类pH敏感的高分子材料成膜性良好,并符合药剂学薄膜衣材料的有关要求。HPMCAM的pH敏感值为3.0～3.7,而HPMCT的pH敏感值为3.8～4.2。包衣片的体外释放试验表明,以HPM- CAM及HPMCT为膜材料制备的包衣片在人工胃液中2 h均未见药物释放,HPMCAM包衣片在pH 3.5左右可迅速释药,而HPMCT包衣片则在pH 4.2左右可迅速释药。结论HPMCAM可作为十二指肠溃疡时药物定位释放包衣材料,HPMCT可用于正常生理情况下十二指肠定位释药包衣材料。     

Pluronic-g-poly(acrylic acid) copolymers as novel excipients for site specific, sustained release tablets

Potential utility of copolymers comprising Pluronic^® (PEO–PPO–PEO) surfactants covalently conjugated with poly(acrylic acid) (PAA) as excipients for sustained-release tablets was explored. Apparent particle density, particle size distribution, Carr index, thermal stability, and compression behavior of the Pluronic–PAA copolymers were characterized. Tablets prepared by direct compression of blends of Pluronic–PAA copolymers were evaluated on the basis of their thermomechanical profile, crushing strength, friability, and drug release properties. Small molecular weight drugs of aqueous solubility decreasing in the order theophylline > hydrochlorothiazide > nitrofurantoin were incorporated to the tablets. For comparison purposes, tablets were also prepared from PAA of Carbopol^® 71G (C71G), and mixtures of C71G and Pluronic^® F127, with each of the above three drugs. The Pluronic–PAA aggregates are stabilized by hydrophobic associations between poly(propylene oxide) (PPO) segments in aqueous solutions, and thus require higher ionization of the carboxylic groups to overcome the associations and swell. The swelling pattern of the Pluronic–PAA copolymers is more dramatically pH-dependent than that of Carbopol lacking any hydrophobic associations. The drug retention in and release from the Pluronic–PAA based tablets is profoundly pH-dependent and hence specific to the pH exceeding that of the pK_a > 5 of these copolymers. Theophylline- and hydrochlorotiazide-containing tablets made with Pluronic–PAA copolymers showed a reduced release rate under acidic conditions compared to the neutral or alkaline conditions, while the opposite pattern was observed with the Carbopol-based tablets due to the different pH-dependent swelling behavior of the polymers. Nitrofurantoin-containing tablets showed a remarkably low drug release rate owing to the strong hydrophobic character of nitrofurantoin and of its complexes with the copolymers. Integrity of the nitrofurantoin-containing tablets was maintained during the 24 h release test. Zero-order kinetics of the cumulative release profile of all drugs under study was observed with the Pluronic–PAA as a tablet excipient. Adequate mechanical properties, the self-assembling behavior, and the pH-sensitiveness of the Pluronic–PAA copolymers make them promising excipients for tablets with preferential delivery into a neutral to alkaline pH environment.     

Photodynamic therapy of human bladder carcinoma cells in vitro with pH-sensitive liposomes as carriers for 9-acetoxy-tetra-n-propylporphycene

In vitro experiments were performed on human bladder carcinoma cells to evaluate the efficiency of the recently synthesized photosensitizer 9-acetoxy-tetra-n-propylporphycene (ATPPn) for photodynamic therapy. To improve cytoplasmic delivery of this hydrophobic compound, we prepared pH-sensitive liposomes composed of phosphatidylethanolamine (PE) and cholesteryl hemisuccinate (CHEMS) in comparison with pH-insensitive liposomes consisting of phosphatidylcholine (PC) and CHEMS. Dynamic light scattering measurements were used to monitor the acid-induced liposome destabilization. After incubation with liposome-bound ATPPn, bladder carcinoma cells were irradiated by a dye laser with increasing light fluence rates from 1 to 48 J/cm². The photodynamic effects were then assessed from cell survival curves. No dark or phospholipid toxicity was measured for 2 g ATPPn/1.5 ml medium. Qualitative cellular uptake of ATPPn was determined by fluorescence microscopy, while photodamage was elucidated by transmission and scanning electron microscopy. Absorption spectra performed up to 42 days revealed changes in shape for the pH-sensitive liposomes after storage at room temperature. ATPPn was proved to be an encouraging photosensitizer, capable of reducing cell survival to 0.1% after short-term incubation of 60 min with a drug dose of 2 g ATPPn/1.5 ml medium. Although pH-sensitive PE/CHEMS liposomes showed significantly (P<0.05) more photokilling effects at 24 J/cm² and 48 J/cm², no further advantages over non-pH-sensitive PC/CHEMS liposomes were found.     

Combination prostate cancer therapy: Prostate-specific membranes antigen targeted,pH-sensitive nanoparticles loaded with doxorubicin and tanshinone

Prostate cancer is the second most frequently diagnosed cancer in the men population. Combination anticancer therapy using doxorubicin (DOX) and another extract of traditional Chinese medicine is one nano-sized drug delivery system promising to generate synergistic anticancer effects, maximize the treatment effect, and overcome multi-drug resistance. The purpose of this study is to construct a drug delivery system for the co-delivery of DOX and tanshinones (TAN). Lipid nanoparticles loaded with DOX and TAN (N-DOX/TAN) were prepared by emulsification and solvent-diffusion method. PSMA targeted nanoparticles loaded with DOX and TAN (P-N-DOX/TAN) were synthesized by conjugating a PSMA targeted ligand to N-DOX/TAN. We evaluate the performance of this system in vitro and in vivo. P-N-DOX/TAN has a size of 139.7 ± 4.1 nm and a zeta potential of 11.2 ± 1.6 mV. The drug release of DOX and TAN from P-N-DOX/TAN was much faster than that of N-DOX/TAN. N-DOX/TAN presented more inhibition effect on tumor growth than N-DOX and N-TAN, which is consistent with the synergistic results and successfully highlighting the advantages of combing the DOX and TAN in one system. P-N-DOX/TAN achieved higher uptake by LNCaP cells (58.9 ± 1.9%), highest tumor tissue distribution, and the most significant tumor inhibition efficiency. The novel nanomedicine offers great promise for the dual drug delivery to prostate cancer cells, showing the potential of synergistic combination therapy for prostate cancer.     

Nebulized anionic guanidinylated O-carboxymethyl chitosan/N-2-hydroxypropyltimehyl ammonium chloride chitosan nanoparticles for siRNA pulmonary delivery: preparation,characterization and in vitro evaluation

This study developed a pH-sensitive anionic system composed of guanidinylated O-carboxymethyl chitosan (GOCMCS) and N-2-hydroxypropyltimehyl ammonium chloride chitosan (N-2-HACC) for efficient siRNA delivery to the lungs following nebulization. About 16.8% of guanidine groups were incorporated into O-carboxymethyl chitosan (OCMCS) with the aid of O-methylisourea. Gel electrophoresis images demonstrated that siRNA was successfully encapsulated in nanoparticles ranging from 150 to 180?nm with zeta potential of about ?17?mV. The nanoparticles containing GOCMCS existed superior transfection performance compared with their amino-based analogs. The evaluation in vitro revealed that nanoparticles were internalized into A549 cells by energy-dependent endocytosis, then achieved endosomal escape by direct transmembrane penetration of guanidine moieties as well as swelling behavior of nanoparticles due to the pH sensitivity of GOCMCS. The mRNA level of survivin gene was down-regulated to 6.9% using GOCMCS/N-2-HACC/siSurvivin NPs. The survivin siRNA mediated by nanoparticles caused 30% of cell growth inhibition and induced 19.45% of cell apoptosis, which was comparable to Lipofectamin2000. After nebulization of siRNA-loaded nanoparticles, the stability of siRNA was maintained and fine particle fractions were detected by two-stage impinger that accounted for more than 60%. These results suggested that GOCMCS/N-2-HACC nanoparticles possessed potential as safe and efficient carrier for siRNA pulmonary delivery.     

斑蝥素载药胶束的制备及其体外释药性能考察

目的:制备pH敏感斑蝥素聚合物胶束纳米制剂,以提高斑蝥素在水中的溶解度,并考察该制剂在弱酸性条件下的体外释药特性。方法:以聚乙二醇-聚乳酸共聚物[poly(ethylene glycol)-b-polylactide,PELA]和聚乙二醇-聚乳酸-聚(β-氨基酯)[poly(ethylene glycol)-b-polylactide-b-poly(β-amino ester),PELA-PBAE]为载体,采用薄膜水化法制备斑蝥素胶束。通过透射电子显微镜观察胶束的微观形态,采用粒度分析仪测定粒径,HPLC测定其载药量和包封率,透析袋透析法测定纳米胶束在不同p H条件下的释放特性。结果:斑蝥素胶束呈明显的球状结构,PELA载药(PELA-C)胶束和PELA-PBAE载药(PELAPBAE-C)胶束的粒度分别为21.6,21.2 nm,且至少在5 d内稳定;载药量分别为1.68%和1.72%,包封率分别为92.0%和88.8%;在p H 5.5下的8 h累计释放率分别为24.7%和79.1%,在p H 6.5下的8 h累计释放率分别为13.6%和50.0%,在p H 7.4下的8 h累计释放率分别为10.2%和13.9%。结论:PELA-PBAE作为纳米载体能明显提高斑蝥素的水溶性,体外释药具有显著的p H响应性能,在抗肿瘤药物的开发方面具有较好的应用前景。     

Assessment of the drug loading,in vitro and in vivo release behavior of novel pH-sensitive hydrogel

Context: As a glucocorticoid drug, dexamethasone has good therapeutic effects for ulcerative colitis. pH-sensitive hydrogels could make conventional changes of volume in response with different pH values. Meanwhile, they could load drugs depending on its internal three-dimensional network structure.

Objective: Appropriate methods were used to improve the drug-loading capacity of hydrogel and exploring the colon-targeting character of dexamethasone hydrogel.

Materials and methods: Different solvents (ethanol and 1,2-propanediol) were employed to dissolve dexamethasone as well as hydrogel monomer materials (poly(ethylene glycol) methyl ether (MPEG)–poly(lactide acid)–acryloyl chloride macromonomer, itaconic acid (IA) and MPEG–methacrylate), then mixing them together to prepare hydrogel through the heat-initiated free radical polymerization method. Differential scanning calorimetry and X-ray diffraction methods were used to verify whether dexamethasone was loaded into hydrogels. In vitro drug release behavior and in vivo pharmacokinetic study were also investigated in detail.

Results: Dexamethasone was successfully loaded into hydrogel, and its loading capacity was improved (5?mg/g). Both the in vitro release study and the in vivo pharmacokinetic study showed the good colon-targeting character of the pH-sensitive P(LE–IA–MEG) hydrogel (T_max?=?1.0?h, C_max?=?2.16?µg/ml of dexamethasone; T_max?=?3.9?h, C_max?=?0.43?µg/ml of dexamethasone hydrogel).

Discussion: Dexamethasone could be targeted to the colon site by P(LE–IA–MEG) hydrogel, thereby improving its therapeutic effect and reduce its side effects.

Conclusion: P(LE–IA–MEG) hydrogel might have great potential application in colon-targeted drug delivery systems.     

兼具MRI显影增强及pH敏感释药性能的载药Fe3O4纳米颗粒

以聚丙烯酸(PAA)修饰的超顺磁性Fe₃O₄纳米颗粒(MNPs-PAA)为基础,利用pH敏感的腙键将抗肿瘤药物阿霉素(DOX)与磁性颗粒表面的PAA链偶联,制备了载药Fe₃O₄磁性纳米颗粒(MNPs-DOX)。通过透射电镜、X射线衍射、紫外、红外、热失重以及体外磁共振显影(MRI)等手段对MNPs-DOX的形貌、结构、MRI及载释药效果进行了表征。结果证实,MNPs-DOX具有超顺磁性,在MRI中具备良好的横向弛豫(T₂)显影增强效果。此外,其DOX负载率达15%(质量分数),且在pH=5.0的酸性环境中药物释放量明显高于pH=7.4的中性环境,具有对环境pH的敏感性。     

Effect of pH-sensitive nanoparticles on inhibiting oral biofilms

Dental caries is a biofilm-related preventable infectious disease caused by interactions between the oral bacteria and the host’s dietary sugars. As the microenvironments in cariogenic biofilms are often acidic, pH-sensitive drug delivery systems have become innovative materials for dental caries prevention in recent years. In the present study, poly(DMAEMA-co-HEMA) was used as a pH-sensitive carrier to synthesize a chlorhexidine (CHX)-loaded nanomaterial (p(DH)@CHX). In vitro, p(DH)@CHX exhibited good pH sensitivity and a sustained and high CHX release rate in the acidic environment. It also exhibited lower cytotoxicity against human oral keratinocytes (HOKs) compared to free CHX. Besides, compared with free CHX, p(DH)@CHX showed the same antibacterial effects on S. mutans biofilms. In addition, it had no effect on eradicating healthy saliva-derived biofilm, while free CHX exhibited an inhibitory effect. Furthermore, the 16s rDNA sequencing results showed that p(DH)@CHX had the potential to alter oral microbiota composition and possibly reduce caries risk. In conclusion, the present study presents an alternative option to design an intelligent material to prevent and treat dental caries.     

pH-敏感型水凝胶在多肽和蛋白质药物给药系统研究中的应用

目的 介绍和展望pH-敏感型水凝胶对拓展多肽和蛋白质药物给药（TPP-DS）途径的发展方向.方法 整理近10年的文献资料,归纳pH-敏感型水凝胶的制备方法及应用途径.结果 对pH-敏感型水凝胶用于TPP-DS的材料制备、应用研究进展作了系统阐述.结论 pH-敏感型水凝胶的特性对TPP-DS的实现具有重要价值,有待于进一步的研究.