Host-guest interaction of β-cyclodextrin with isomeric ursolic acid and oleanolic acid:physicochemical characterization and molecular modeling study

Ursolic acid(UA) and oleanolic acid(OA) are insoluble drugs. The objective of this study was to encapsulate them into β-cyclodextrin(β-CD) and compare the solubility and intermolecular force of β-CD with the two isomeric triterpenic acids. The host-guest interaction was explored in liquid and solid state by ultraviolet-visible absorption,1H NMR, phase solubility analysis, and differential scanning calorimetry, X-ray powder diffractometry, and molecular modeling studies. Both experimental and theoretical studies revealed that β-CD formed 1: 1 water soluble inclusion complexes and the complexation process was naturally favorable. In addition, the overall results suggested that ring E with a carboxyl group of the drug was encapsulated into the hydrophobic CD nanocavity. Therefore, a clear different inclusion behavior was observed, and UA exhibited better affinity to β-CD compared with OA in various media due to little steric interference, which was beneficial to form stable inclusion complex with β-CD and increase its water solubility effectively.

Interaction between Hosts and Guests of Rural Tourism in Northeast China Based on Symbolic Interaction Theory

With constant economic development and continuous improvement of living standards in Northeast China,rural tourism,as a new type of tourism,is increasingly favored. From the perspective of symbolic interaction theory,taking the current situation of rural tourism in Northeast China as an example,this paper explained the semiotic significance between hosts and guests in rural tourism. It established the evaluation indicators for authentic symbolic perception of rural tourism. Also,combined with the theories of sociology and anthropology,it studied the interaction between hosts and tourists of rural tourism in Northeast China.

Quantitative prediction of the bitterness of atomoxetine hydrochloride and taste-masked using hydroxypropyl-β-cyclodextrin:A biosensor evaluation and interaction study

The bitterness of a drug is a major challenge for patient acceptability and compliance,especially for children.Due to the toxicity of medication,a human taste panel test has certain limitations.Atomoxetine hydrochloride(HCl),which is used for the treatment of attention deficit/hyperactivity disorder(ADHD),has an extremely bitter taste.The aim of this work is to quantitatively predict the bitterness of atomoxetine HCl by a biosensor system.Based on the mechanism of detection of the electronic tongue(Etongue),the bitterness of atomoxetine HCl was evaluated,and it was found that its bitterness was similar to that of quinine HCl.The bitterness threshold of atomoxetine HCl was 8.61μg/ml based on the Change of membrane Potential caused by Adsorption(CPA)value of the BT0 sensor.In this study,the taste-masking efficiency of 2-hydroxypropyl-β-cyclodextrin(HP-β-CyD)was assessed by Euclidean distances on a principle component analysis(PCA)map with the SA402B Taste Sensing System,and the host–guest interactions were investigated by differential scanning calorimetry(DSC),powder X-ray diffraction(XRD),nuclear magnetic resonance(NMR)spectroscopy and scanning electron microscopy(SEM).Biosensor evaluation and characterization of the inclusion complex indicated that atomoxetine HCl could actively react with 2-hydroxypropyl-β-cyclodextrin.

Interaction of host-guest complexes of cucurbit[n]urils with double probe guests

Three guests with two moiety probes for different Cucurbit[n = 6—8]urils have been synthesized. They are N-(2-methylenethiophen)-adamataneamine, N-(2-methylene pyrrole)- adamataneamine and N-(2-methylenefurfuran)-adamataneamine. The probes are methyle-nepyridyl typically for Q[6] and adamataneamine typically for Q[7]. The host-guest complexes of Cucurbit[n = 6—8]urils with these guests have been investigated by using NMR techniques and ESMS method. Also, thermoanalysis has been used for exploring relationship of enthalpy and stability of the host-guest complexes.

A Fluorescent Supramolecular Crosslinked Polymer Gel Formed by Crown Ether Based Host-Guest Interactions and Aggregation Induced Emission

Based on the combination of B21C7/dialkylammonium salt host-guest interactions and tetraphenylethylene （TPE）-based aggregation-induced emission （AIE） effect, a fluorescent supramolecular crosslinked polymer gel was successfully prepared. Compared with the solution of TPE-containing small molecules, this gel exhibited remarkable fluorescence enhancement due to the AIE effect of TPE units. The ＂gelation induced fluorescence emission＂ phenomenon can be explained by the hindered intramolecular rotation of phenyl rings of TPE. Because of the reversibility and stimuli-responsiveness of the B21C7/dialkylammonium salt host-guest interactions, the transition between the fluorescent supramolecular crosslinked polymer gel and the disassembled sol with very weak fluorescence can be realized by adding pH and thermal stimuli. This novel material contributes to the development of supramolecular chemistry, polymer science and fluorescent materials and offers a new method to construct functional supramolecular materials.

Water-soluble supramolecular polymers constructed by macrocycle-based host-guest interactions

Supramolecular polymers, which combined of the supramolecular chemistry and polymer science, are constructed from monomers together by reversible noncovalent interactions. Supramolecular polymers in aqueous solution are especially important due to their superior biocompatibility and environmental adaptation, which determined they have wide applications in various areas, such as drug delivery, selfhealing, shape memory. Macrocyclic compounds, such as cyclodextrins, calixarenes, cucurbiturils and pillar[n]arenes, are the most used building blocks in the preparation of supramolecular polymers.Macrocycle-based supramolecular polymers, which introduce the host-guest interaction in the system,endow these polymers with interesting and smart physical-chemical properties. In this review, we summarized recent studies about supramolecular polymers in aqueous solution based on macrocyclic compounds.

Recent progress on pure organic room temperature phosphorescence materials based on host-guest interactions

Pure organic room temperature phosphorescence(RTP) has been attracting a lot interest recently. So far,many strategies have succeeded in achieving efficient organic RTP materials by increasing the rate of intersystem crossing(ISC) and suppressing non-radiative transitions. In supramolecular chemistry, the control and regulation of molecular recognition based on the role of the host and guest in supramolecular polymers matrix, has attracted much attention. Recently, researchers have successfully achieved room temperature phosphorescence of pure organic complexes through host-guest interactions. The host molecule specifically includes the phosphorescent guest to reduce non-radiative transitions and enhance room temperature phosphorescence emission. This review aims to describe the developments and achievements of pure organic room temperature phosphorescence systems through the mechanism of host-guest interactions in recent years, and demonstrates the exploration and pursuit of phosphorescent materials of researchers in different fields.

A selective and stepwise aggregation of a new fluorescent probe for dinitrate explosive differentiation by self-adaptive host-guest interaction

Nitrate explosive is hard to detect due to lack of aromatic ring and weak interaction with fluorescence probe.More challenging is even to differentiate the dinitrates with multiple nitrate explosives based on photo induced electron transfer or aggregation caused fluorescence change mechanism.A highly selective dinitrate explosive probe was designed based on a new strategy-stepwise aggregation of multiple anchored fluorene dimer 8Py-2 F.Compared with its monomer counterpart 2Py-F,8Py-2 F showed a selective and stepwise fluorescence quenching to dinitrate explosives-ethylene glycol(EGDN)and triethylene glycol dinitrate(TEGDN).The limits of detection(LODs)are 2.72μM for TEGDN and 0.46μM for EGDN,which is three orders of magnitude lower than those of 2Py-F.The stepwise quenching process is well matched with the stepwise aggregation process as evidence by scanning electron microscopy(SEM).Nuclear magnetic resonance(NMR)and quantum chemical calculation proved the interaction force between the dinitrate and 8Py-2 F is hydron bonding interaction,and interaction distance is far less than that of the multiple nitrates coming from the flexibility of the chain and steric hinderance,which resulted in a self-adaptive interaction and higher selectivity.The new strategy is beneficial for the differentiation of the chemicals with similar energy level which is difficult to realize via other method,and the new method provides fluorometric probe for dinitrate explosive detection and makes it an ideal candidate for chemical detection and analysis in public safety and environmental monitoring.

Host-Guest Interactions between N,N＇-Bis（ferrocenylmethyl- ene）-Diaminobutane and Benzenetetracarboxylic Dianhydride Bridged Bis（β-cyclodextrin）s

A novel water soluble ditopic guest, the quaternary ammonium salt of N,N＇-bis（ferrocenylmethylene）-diaminobutane （1）, and a known water soluble ditopic host, benzenetetracarboxylic dianhydride bridged bis（β-cyclodextrin）s （2）, have been synthesized and characterized. ^1H NMR spectra and cyclic voltammogram （CV） studies revealed the host-guest interactions between them in aqueous solution. The supramolecular interaction also exists in solid state as confirmed by the studies of the solid samples, which were obtained by frozen-drying the solution sampies, using FTIR spectroscopy and differential scanning calorimetry （DSC） techniques. TEM measurement demonstrated that wire-shaped supramolecular aggregates exist in the aqueous solution of the two compounds. The lengths of the aggregates could reach micrometers.

A simple and sensitive assay for apurinic/apyrimidinic endonuclease 1activity based on host-guest interaction of β-cyclodextrin polymer and pyrene

Apurinic/apyrimidinic endonuclease 1（APE1） plays an important role in protecting the fidelity of genetic material and is also a promising biomarker of cancers. Herein, a simple and sensitive fluorescent method for APE1 activity detection was designed based on host-guest interaction between β-cyclodextrin polymer（β-CDP） and pyrene. In this method, pyrene-labelled DNA probes（AP-S1 S2） and β-CDP functioned as fluorescent signal producer and enhancer, respectively. When APE1 was absent, pyrene on the AP-S1 S2 could not enter the cavity of β-CDP because of steric hindrance, leading to a weak fluorescence intensity/anisotropy. When APE1 was present, it would recognize and cleave AP site in APS1 S2, thus producing a dissociated pyrene-labelled oligonucleotide segment. Pyrene labelled at the 50 end of oligonucleotide segment could be easily trapped into the cavity of β-CDP via host-guest interaction, leading to a significant enhancement of fluorescence intensity/anisotropy. This assay offered a dynamic range of 0.05 U/m L–5 U/m L and an estimated detection limit of 0.05 U/m L. Furthermore,assessment of APE1 activity in He La cell extracts was successfully implemented, which hold the potential for APE1-related cancer diagnosis and biological researches.

A facile approach toward multicolor polymers:Supramolecular self-assembly via host-guest interaction

A one-step and facile strategy toward the construction of multicolor polymers via supramolecular selfassembly was proposed.Multicolor polymers were simply prepared by the self-assembly of adamantane-labeled fluorescein,adamantane-labeled rhodamine B and β-cyclodextrin polymers via host-guest interaction between β-cyclodextrin and adamantane.Multicolor polymers showed several interesting properties：multiple emission signatures by a single wavelength excitation,easy tunability,intense fluorescence,high photostablility.In addition,the self-assembly approach implied a facile and flexible strategy for constructing functionalized materials,such as multicolor materials for biological labeling and imaging,and sensing materials for the detection of physiological parameters.

民宿促进各民族交往交流交融的价值协同路径研究——以新疆伊宁市六星街和喀赞其民宿为例

民宿是旅游促进各民族交往交流交融(简称旅游促“三交”)的重要载体,民宿主客互动过程也是各民族交往交流交融过程。研究以价值协同论与符号互动论为理论基础,选择伊宁市六星街和喀赞其历史街区周边民宿为研究对象,通过网络文本分析与扎根理论方法,探究民宿主客互动促进各民族交往交流交融的价值协同路径。研究表明:(1)民宿主与游客之间除传统的信息、物质、情感等互动形式外,学习互动是推进旅游促“三交”的重要基础;(2)民宿主客互动受到非言语、言语、技术、情境、政策制度、公平感知及过往经历等因素的综合影响;(3)民宿主客互动促进了主客价值协同,强化了文化和国家认同,夯实了中华民族共同体构建的心理基础。研究有助于厘清民宿场域旅游促“三交”的机理,也可为民族地区民宿业高质量发展提供参考。

含环糊精丙烯酸酯共聚物智能抗菌涂层的制备及应用

研制先进智能抗菌涂层对于防治医疗器械、公共环境的细菌污染具有重要意义。将丙烯酸烷基酯与甲基丙烯酸酯基团功能化的β-环糊精(β-CD)和膦酸酯与作为共聚单体,通过自由基聚合制备具有主客体相互作用和较强黏附性的丙烯酸酯共聚物涂层。小分子抗菌剂百里香酚(THY)可作为客体分子被包合至共聚物中β-CD结构单元的空腔中。由于主客体作用的可逆性,共聚物涂层在弱酸性(pH=5)条件下发挥智能缓释作用,实现小分子抗菌剂逐步释放。结果表明:智能抗菌涂层对大肠杆菌(E.coli)和金黄色葡萄球菌(S.aureus)的生长有明显抑制作用。特别当β-CD在共聚物中的质量分数达到45%时,涂层对S.aureus的抑菌率接近100%。此外涂层对多种基材均有优异的附着力,拉开法附着力可达10 MPa以上。这类共聚物涂层的制备为开发智能抗菌涂层提供了有效策略。

“主客交”“主客浑受”理论内涵探析

“主客交”理论出自吴又可《温疫论》,后世医家薛生白在其启发下提出了“主客浑受”理论,在形成上皆因正气亏虚、气血困顿,正气与客邪胶锢于血脉,用药上运用灵动攻走之物消除血脉之痼疾。但二者各有不同,吴氏认为“主客交”病机为邪火独存,胶锢客邪于十二经之血脉,病位在表,用药在消瘀剔邪的基础上,更注重补益人体气血偏虚;而薛氏继承了吴氏对于“主客交”理论内涵的认识,将“主客交”由疫病扩大到湿热性质疾病,认为“主客浑受”为脾虚复感湿热之邪,继而邪气深入厥阴血脉,病位在里,用药注重化瘀通络,更针对厥阴血脉瘀结之证。

多维距离对民宿游客行为意向的影响:兼论主客互动的调节效应

地理距离一直被视为理解旅游需求和游客行为的重要因素。基于阳朔民宿旅游者的问卷调查数据,综合运用结构方程建模技术,分析了多维距离对民宿游客行为意向的影响机理,检验主客互动的调节作用。研究结果表明:①空间距离、经济距离和区位距离是提升民宿形象的重要因素,而区位距离对民宿依恋具有负向作用。②民宿形象和依恋在多维距离与游客行为意向的关系中发挥了中介效应,民宿依恋在民宿形象与游客行为意向的关系中发挥了中介作用。③不同维度的主客互动在民宿游客行为意向机理中发挥着差异化的调节效果。信息互动和人际互动分别在民宿形象与依恋、经济距离与民宿形象的关系中发挥了正向和负向的调节作用。服务互动正向调节空间距离对民宿形象的影响,并负向调节民宿依恋对行为意向的作用。多维距离对游客行为意向的影响分析,不仅揭示了一种新型人地关系,丰富了社会互动理论和距离的引力机制,还扩展了旅游者行为意向的研究成果,为旅游行为决策机理提供新的解释视角。

乡村旅游场域非对称权力关系下的东道主凝视

凝视理论自其诞生之初便伴随着权力的审视与规训,旅游凝视也同样如此。在旅游主客之间的权力关系中,游客通常被视为优势权力者,然而在现实中所表现出来的是东道主同样具有凝视游客的权力。文章从东道主凝视的角度出发,选取雄安新区W村作为案例地,揭示游客与东道主之间权力关系及其转变过程,发现东道主为制衡游客权力、保护自身利益而采取的4种方案:隐晦抵抗、公开抵抗、合作和消极一致。研究发现,通常被认为处于权力低位的东道主也具有使游客按照其预期方式行事的手段,从而促进主客平衡和良性互动的实现,还创造性地提出游客凝视与东道主凝视相互影响的理论框架。为最大限度保护主客双方利益,应自上而下调整乡村旅游场域中的权力分配,以促进乡村旅游可持续发展。

跨地方民族演艺者的社会接触与角色变迁——以佤族艺人为例

旅游演艺在特定时空条件下加剧多元主客文化交往和跨文化互动。我国民族演艺人才逐渐成为旅游劳工移民、少数民族多元社会角色交织的跨地方旅游演艺从业者,其多重的社会接触将有助于阐释旅游情境中的关系复杂性,进一步跳出传统在地性民族旅游演艺研究的范畴。文章选取佤族艺人为案例,以质性研究方法深入探讨旅游情境下跨地方民族演艺者的社会接触特点及其角色变迁。研究发现:跨地方民族演艺者进入旅游情境中,经历了文化交往向职业交往导向叠加的社会接触,加快推进了现代角色多元化进程;同时,旅游情境构建了一个多重社会接触空间,为他们角色管理适应整体社会结构变化提供了缓冲,彰显出从业者主体性视角下旅游情境的社会结构特征。该研究从旅游从业者的视角,为民族文化繁荣如何赋能新时代旅游高质量发展提供有益见解。

基于“主客交”理论探析艾滋病发热病机及辨治思路

“主客交”理论出自吴有性《温疫论》,原用于指导温疫病的治疗,经后世医家补充发展,现多用于指导临床正虚邪恋之痼疾的治疗。艾滋病发热是人体感染人类免疫缺陷病毒(HIV)后,免疫功能被破坏,出现的各种机会性感染及肿瘤引起的一种常见临床症状。艾滋病发热的发生发展与“主客交”理论中正虚邪恋、外邪胶结于血脉、主客交浑的病机特点相似,故从“主客交”理论切入,探讨艾滋病发热的病机和辨治思路。认为肺卫不固,不能抵御外邪;脾气虚弱、气血津液耗伤、艾毒稽留、内生病理产物郁积,正气无力透邪为艾滋病发热的主要病机。在吴有性所创三甲散和“扶正祛邪,分离主客”治疗原则启示下,提出辨治艾滋病发热的思路,即透邪外出,引客离主;抓住本质,勿忘扶正;补托并用,分离主客。

基于主客交理论辨治新冠后症状

主客交理论为明代医家吴又可所创,指瘟疫后期正邪相争、胶固缠绵的病理特征。后世医家相继对其发挥,指导瘟疫、内伤杂病等治疗。疫疠毒邪致病深重,引发脏器损伤,恢复期常遗留长期症状,影响患者生活质量。新冠后症状的病机特点以正气损伤(伤气、伤阴、伤形、伤神)和余邪未尽(夹湿、夹痰、夹瘀)为主,病机与主客交相符,因正气虚损,无力托邪外出,邪与血交浑,出现多系统症状,并有形成痼疾的风险。治疗上,注重扶正,及时溃散血中伏藏之毒邪,并随其所得而攻之,兼以祛湿、化痰、利水、清热、散瘀,重视肺间质纤维化防治,临床可仿三甲散化裁治疗。梳理主客交理论源流及内涵,基于主客交理论探讨新冠后症状的病因病机与诊治思路,以期对新冠后症状的中医诊疗提供参考与借鉴。

“主客交”理论在子宫颈癌前病变中的应用

基于“主客交”理论结合现代医学研究,探讨子宫颈癌前病变的发病机制及中医药应用策略。子宫颈癌前病变的主要病因病机为肝脾肾之“主”失调,加之痰湿热毒之“客”邪内聚、蕴结,终成癥瘕,渐成痼疾,发为宫颈癌前病变并趋向恶性发展。治以“扶正达邪,分离主客”,在疏肝健脾固肾的同时厘清主客强弱,精准辨证。分阶段灵活选用清热、祛湿、解毒、理气、活血、化瘀等“通”法以祛邪通络。