Poly(N-isopropylacrylamide)/mesoporous silica thermosensitive composite hydrogels for drug loading and release

Temperature-sensitive hydrogels are attracting increasing attention for controlled drug delivery. However, achieving high drug loadings and sustained drug release remains challenging. Herein, we describe the successful synthesis of a series of novel temperature-sensitive poly(N-isopropylacrylamide) (PNIPA)/mesoporous silica nanoparticles (MSN) hydrogels by physical crosslinking of NIPA with MSN. The external and internal structures, temperature sensitivity, drug-loading capacity, and blood compatibility of the PNIPA/MSN composite hydrogels are studied. Results show that MSN addition improved the network structure and adjusted the size of the hole, MSN could also act as drug carrier, thereby enhancing the drug loading capacity. The composite hydrogels underwent a phase transition at 33.7 °C (at the lower critical solution temperature). The hemolysis rate of the composite hydrogels was less than 1%, thus they can be classified as a nonhemolytic materials with good biocompatibility. The composite hydrogels reported here thus have great potential in drug transport and temperature-activated drug release. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48391.     

星点设计-效应面法优化盐酸川芎嗪眼用温度敏感型原位凝胶的处方

探讨星点设计-效应面法优化盐酸川芎嗪眼用温度敏感型原位凝胶的处方。采用泊洛沙姆407和泊洛沙姆188为温敏材料,以模拟泪液稀释前后的溶液-凝胶相转变温度为考察指标,采用星点设计-效应面法对处方进行优化并进行验证。经过优化的处方组成为22.5%泊洛沙姆407和5%泊洛沙姆188;优化处方制备的凝胶在26.9℃为自由流动的液体,经模拟泪液稀释后在32.5℃转变为凝胶。星点设计-效应面法适用于盐酸川芎嗪眼用温度敏感型原位凝胶的处方优化,所建立的模型预测性良好,该眼用温敏凝胶符合眼部应用要求。     

β‐Cyclodextrin inclusive interaction driven separation of organic compounds

A novel selective separation method for organic compounds, especially thermosensitive substances, has been proposed using unsubstituted β‐cyclodextrin (β‐CD) as a host and some alcohols and aldehydes as model guests in aqueous solution. The separation factors were evaluated from the extraction of an equimolar mixture of alcohol and aldehyde compounds. The inclusion equilibrium constants for several alcohols and aldehydes over β‐CD have been calculated through their UV‐vis spectra. The Gibbs free energy changes of β‐CD/substrates complexes (ΔG) have been calculated combined B3LYP/6‐31G(d)//ONIOM2(B3LYP/6‐31G(d):PM3) with semicontinuum solvation model. The difference of Gibbs free energy changes (ΔΔG) for the inclusion complexes formed via the intermolecular weak interactions e.g., hydrogen bond and electrostatic interaction was the reason why alcohol and aldehyde compounds could be selectively separated. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Thermosensitive bioadhesive gels for the vaginal delivery of sildenafil citrate: in vitro characterization and clinical evaluation in women using clomiphene citrate for induction of ovulation

Objective: The objective of this study is to develop and characterize in situ thermosensitive gels for the vaginal administration of sildenafil as a potential treatment of endometrial thinning occurring as a result of using clomiphene citrate for ovulation induction in women with type II eugonadotrophic anovulation. While sildenafil has shown promising results in the treatment of infertility in women, the lack of vaginal pharmaceutical preparation and the side effects associated with oral sildenafil limit its clinical effectiveness.

Methods: Sildenafil citrate in situ forming gels were prepared using different grades of Pluronic^® (PF-68 and PF-127). Mucoadhesive polymers as sodium alginate and hydroxyethyl cellulose were added to the gels in different concentrations and the effect on gel properties was studied. The formulations were evaluated in terms of viscosity, gelation temperature (T_sol-gel), mucoadhesion properties, and in vitro drug release characteristics. Selected formulations were evaluated in women with clomiphene citrate failure due to thin endometrium (Clinicaltrial.gov identifier NCT02766725).

Results: The T_sol-gel decreased with increasing PF-127 concentration and it was modulated by addition of PF-68 to be within the acceptable range of 28–37?°C. Increasing Pluronic® concentration increased gel viscosity and mucoadhesive force but decreased drug release rate. Clinical results showed that the in situ sildenafil vaginal gel significantly increased endometrial thickness and uterine blood flow with no reported side effects. Further, these results were achieved at lower frequency and duration of drug administration.

Conclusion: Sildenafil thermosensitive vaginal gels might result in improved potential of pregnancy in anovulatory patients with clomiphene citrate failure due to thin endometrium.     

Thermosensitive fibres of lyocell/poly(N‐isopropylacrylamide): multiparametric analysis for studying the graft copolymerization

The thermosensitive properties of the hydrogel poly(N‐isopropylacrylamide) (pNIPAAm) together with the good mechanical properties of lyocell fibres make a combination of the two to be thought of as a smart textile. In the present study the optimal values of various parameters that control the grafting process of pNIPAAm onto lyocell fibres were determined considering the influence of the interaction between them. The copolymerization of pNIPAAm hydrogel onto lyocell fibres was performed in aqueous acidic medium using cerium(IV) as initiator. An experimental design was planned in order to study the effect of the interactions between some variables that affect the kinetics of the graft copolymerization: the cerium(IV) initiator concentration, the N‐isopropylacrylamide (NIPAAm) monomer concentration and the liquor fibre‐to‐bath ratio. The results show that the interaction between the concentrations of NIPAAm and the initiator significantly affects the degree of grafting (DG), the optimum values being 1250 and 12.25 mmol L^?1, respectively. In contrast, the liquor ratio parameter shows no significant interaction with the other two variables studied, meaning that it acts independently but showing a proportional relationship with respect to the DG obtained. In addition, the presence of pNIPAAm in the copolymer obtained was confirmed by Fourier transform infrared spectral analysis. Moreover, the water sorption capacity, depending on the temperature, of the lyocell/pNIPAAm copolymer was studied, with an increase being observed when the DG is higher than 60% and also increasing with the temperature.© 2012 Society of Chemical Industry     

BaTiO3系PTC热敏电阻用施主加入物的研究

阐述了常用的施主加入物、施主加入量、影响施主加入量的主要因素及各施主加入物的特点。研究了常用的施主加入物的理化指标对ＰＴＣ热敏电阻性能的影响，并据此提出了其技术标准。     

亲水型温敏凝胶聚合物的制备与性能分析

温敏高分子材料因其对温度具有敏感性而被应用于温控开关及药物控温释放等领域.本文以N-异丙基丙烯酰胺(NIPAm)、甲基丙烯酰胺(MAm)作为单体,过硫酸钾作为引发剂,采用N,N’-亚甲基双丙烯酰胺(BIS)作为交联剂,制备了亲水型温敏凝胶聚合物,并研究了两种单体组分的质量分数比及交联剂的用量对所制备的凝胶聚合物的低临界溶液温度(LCST)、溶胀率和保水率的影响.研究结果表明:合成的N-异丙基丙烯酰胺与甲基丙烯酰胺的凝胶聚合物(简写为P(NI-PAm-co-MAm))的低临界溶液温度(LCST)随着凝胶聚合物体系中亲水单体比例的增加而升高;交联剂含量越多,则凝胶聚合物的溶胀率越小,而保水率增大;凝胶聚合物的亲水单体比例增加,则凝胶聚合物的溶胀率和保水率均增大.     

赴日考察热敏纸增感剂—四甲基二苯乙烷及国内动态

围绕热敏纸增感剂--四甲基二苯乙烷产品状况,结合赴日考察日本旭电化株式会社的情况,简单介绍该产品性能、用途及市场前景等.     

坚持科技创新发展特种涂布纸

本文介绍了冠豪高新技术股份有限公司坚持科技创新,发展特种涂布纸的作法,对无碳复写纸、热敏纸、彩色喷墨打印纸、特种标签纸的技术和市场发展作了评述.     

PLA表面温敏性互穿网络水凝胶的UV接枝及其透湿性

为制备一种温度响应型智能调湿织物,采用丙烯酸间苯二酚二缩水甘油酯在聚乳酸(PLA)非织造布表面通过热处理引入不饱和双键,在紫外光照射下引发聚丙烯酰胺/聚(N-异丙基丙烯酰胺)(PAAM/PNIPAAM)互穿网络水凝胶体系接枝于PLA非织造布表面。分析接枝后织物的化学结构、形貌,探究PNIPAAM用量在不同温度下对织物透湿性的影响。结果表明,PLA非织造布表面不饱和双键预处理-紫外光接枝两步法可以成功实现温敏性互穿网络水凝胶与PLA非织造布的接枝,所构建的织物表面具有丰富的孔隙结构,互穿网络中PNIPAAM质量分数为4.5%、AAM质量分数为10%时,接枝织物在24℃下的透湿量为1731 g/(m²·d),在38℃下的透湿量高达3601 g/(m²·d),赋予PLA非织造布温度可控的智能透湿性能,将其应用于伤口敷料领域可在低温低透湿性时保持伤口湿润、高温高透湿性时降低创面温度。