Hydrophobically Modified Poly(acrylic acid) Using 3‐Pentadecylcyclohexylamine: Synthesis and Rheology

Summary: Hydrophobically modified poly(acrylic acid) was synthesized using 3‐pentadecylcyclohexylamine (3‐PDCA), which was in turn synthesized from 3‐pentadecylphenol, one of the components of cashew‐nut shell liquid (CNSL), a renewable resource material. ¹H NMR spectra confirmed the incorporation of 3‐PDCA onto PAA and a series of HMPs with three different molar concentrations, viz ? 3, 5 and 7 mol‐% of 3‐PDCA, were synthesized. An increase in viscosity with increasing hydrophobic content was observed by rheological measurements. The critical association concentrations were determined using an Ubbelohde viscometer and a controlled stress rheometer. The stability of HMPs towards temperature and shear was studied. Rheological measurements showed that there was a steady increase in viscosity with increase in hydrophobe content due to the formation of reversible networks. These polymers exhibited gel‐like behavior at low concentrations (≥2 wt.‐%) with an apparent yield stress (ca. 10 Pa) and showed shear thinning properties (non‐Newtonian). However, below a critical concentration, c [η], they showed Newtonian behavior.

η_sp of unmodified and modified PAA‐Na at various polymer concentrations.     

Development and in Vitro Evaluation of Systems to Protect Peptide Drugs from Aminopeptidase N

Purpose. Develop and evaluate systems to prevent aminopeptidase N caused enzymatic degradation of perorally administrated peptide drugs. Methods. Bacitracin was covalently bound to the unabsorbable carrier matrix poly(acrylic acid) (paa) in order to avoid any dilution effects of the inhibitor in the intestine as well as systemic toxic side effects. The inhibitory effect of this conjugate, of neutralized paa and N-acetylcysteine was evaluated using a brush border membrane model. Results. Whereas within 6 h of incubation 65.3 ± 3.7 mol/1 of the substrate (L-leucine p-nitroanilide) was hydrolyzed under our assay conditions, this metabolism was reduced to 44.5 ± 6.3 mol/1 and 49.0 ± 8.8 mol/1 (n = 3–5; ± S.D.) using 1.5% bacitracin-polymer conjugate and 0.5% N-acetylcysteine, respectively. The same amount of bacitracin as immobilized to the polymer exhibited a comparably weaker inhibitory effect. Neutralized paa did not inhibit membrane bound aminopeptidase N. Covering the membrane with a thin mucus layer led to a significantly lowered inhibitory effect of all tested agents. Conclusions. The immobilization of enzyme inhibitors to a carrier matrix and the use of N-acetylcysteine as a novel inhibitor are promising strategies in order to overcome the enzymatic barrier caused by membrane bound peptidases. However the use of effective mucolytic agents seems to be a prerequisite.     

醋酸乙烯—二乙烯基苯共聚反应动力学

根据文献查得的Ｑ,ｅ值,计算了醋酸乙烯－二乙烯基二元共聚的竞聚率,预测其共聚的可能性。以甲苯为汽油为致孔剂,采用悬浮聚合方法合成该二元大孔共聚物。红外光谱分析跟踪共聚反应过程中乙酰氧基和苯环相对比例的变化,并测定共聚反应过程中比表面积,孔率和平均孔径的变化。     

原子转移自由基聚合法合成含羟基星状共聚物

以２－溴异丁酸季戊四醇四酯为引发剂在ＣｕＢｒ／ｂｐｙ催化下实施苯乙烯和丙烯酸β－羟丙酯原子转移自由基共聚合,结果表明聚合物的分子量与理论分子量接近,聚合反应具有活性聚合的特征。进一步对聚合产物进行ＧＰＣ,Ｈ－ＮＭＲ,ＩＲ和羟值滴定分析,表明合成的星状共聚合物中同时具有苯乙烯和丙烯酸β－羟丙酯结构单元,而且羟基在聚合物中近似均匀分布。     

Surgically Controlled, Transpedicular Methyl Methacrylate Vertebroplasty with Fluoroscopic Guidance

Summary  The authors report a series of 13 patients with osteoporotic vertebral fractures treated by transpedicular vertebroplasty. Because of a neurological complication due to posterior leakage of acrylic cement the classical percutaneous approach was converted to an open surgical procedure. The latter allows direct visual control of neural structures and immediate removal of spilled cement, thus eliminating the danger of compressive, chemical and thermal effects of methyl methacrylate on neural elements.  By use of this elegant technique primary stability of fractured vertebras is obtained leading to prompt pain relief in all patients. Surgically controlled vertebroplasty can be used in conjunction with internal fixation. By having studied the different ways of cement escape in their patients, the authors are convinced that surgically controlled vertebroplasty is safer than percutaneous vertebroplasty.     

卡托普利控释微丸的研制

目的：制备卡托普利控释微丸，并对其释药情况进行研究。方法：在流化床内，用丙烯酸树脂RL30D和丙烯酸树脂RS30D的混合物作为包衣材料制备卡托普利控释微丸，对包衣材料配比及包衣材料用量进行选择，对微丸体外释药方程进行研究，采用加速试验法考察微丸释药稳定性。结果：包衣材料最佳配比丙烯酸树脂RL30D-丙烯酸树脂RS30D为1：5，包衣材料最佳用量为包衣增重20％，微丸的体外释药方程为Q＝0．09614t-0．008379(r＝0．9980)，释药稳定性好。结论：卡托普利控释微丸具有良好的零级释药特征。     

温敏性高分子材料对药物释放的研究

 目的合成一系列温度敏感性(温敏性)凝胶，测定其低临界溶液温度(相变温度)。筛选出具有与人体体温相近的相变温度的凝胶，并使其可以作为药物的载体。方法采用自由基水溶液聚合的方法合成共聚物，然后用聚合物承载药物并用高效液相色谱法测其不同温度下药物的释放情况。结果温敏性凝胶可以作为自控式或缓释药用辅料，但如果相变温度低于人体体温，则无实际应用意义。采用共聚合的方法，确可提高凝胶的相变温度。不同条件下合成的共聚物有着不同的相变温度，药物释放情况也不同。结论调整不同组成比例及交联剂的浓度，可使此类凝胶作为自控式或缓释药用辅料成为可能。     

嵌段共聚物在给药系统中的应用

嵌段共聚物作为一类重要的高分子材料在药学中应用广泛。本文结合近几年的研究报道，对嵌段共聚物在给药系统中作为水凝胶、微球、纳米球等的应用以及部分嵌段共聚物的生物降解性和生物相容性作出简要综述。