Synergistic Approaches in the Design and Applications of UCST Polymers

This review summarizes recent progress in the synergistic design strategy for thermoresponsive polymers possessing an upper critical solution temperature (UCST) in aqueous systems. To achieve precise control of the responsive behavior of the UCST polymers, their molecular design can benefit from a synergistic effect of hydrogen bonding with other interactions or modification of the chemical structures. The combination of UCST behavior with other stimuli-responsive properties of the polymers may yield new functional materials with potential applications such as sensors, actuators, and controlled release devices. The advances in this area provide insight or inspiration into the understanding and design of functional UCST polymers for a wide range of applications.

Human cytomegalovirus UL36 inhibits IRF3-dependent immune signaling to counterbalance its immunoenhancement as apoptotic inhibitor

Apoptotic inhibition and immune evasion have particular importance to efficient viral infection, while a dilemma often faced by viruses is that inhibiting apoptosis can up-regulate antiviral immune signaling. Herein, we uncovered that in addition to inhibiting caspase-8/extrinsic apoptosis, human cytomegalovirus (HCMV)-encoded UL36 suppresses interferon regulatory factor 3 (IRF3)-dependent immune signaling by directly targeting IRF3 to abrogate IRF3 interaction with stimulator of interferon genes or TANK-binding kinase 1 and inhibit IRF3 phosphorylation/activation. Although UL36-mediated caspase-8/extrinsic apoptosis inhibition enhances immune signaling, the immunosuppressing activity of UL36 counterbalances this immunoenhancing "side effect" undesirable for virus. Furthermore, we used mutational analyses to show that only the wild-type, but not the UL36 mutant losing either inhibitory activity, is sufficient to support effective HCMV replication in cells, showing the functional importance of the dual inhibition by UL36 for the HCMV life cycle. Together, our findings demonstrate a sophisticated mechanism by which HCMV tightly controls innate immune signaling and extrinsic apoptosis for efficient infection.

Renin-angiotensin system inhibitors improve the survival of cholangiocarcinoma: a propensity score-matched cohort study

BACKGROUND

Hypertension is a risk factor for cholangiocarcinoma (CCA). The effect of anti-hypertensive drugs on the prognosis of CCA is not clear.

METHODS

This is a retrospective study of 102 patients (56.9% males, median age 66 years) diagnosed with CCA and hypertension concurrently and received radical surgery (R0), with a median follow-up of 36.7 months. Kaplan-Meier analysis, Cox regressions, and propensity score (PS) matching were applied for statistical analysis.

RESULTS

Results of multivariable cox analysis showed that renin-angiotensin system inhibitors (RASis) usage was a protective factor for progression-free survival (PFS) (hazard ratio [HR] = 0.55, 95% confidence interval [95% CI]: 0.32-0.96) and overall survival (OS) (HR = 0.40, 95% CI: 0.20-0.79), respectively. Calcium channel blockers, diuretics, and β-blockers didn't show significant associations. The association of RASis usage and PFS and OS was derived by PS matching, with a cohort of 28 RASis users and 56 RASis non-users. The median PFS and OS of RASis users (PFS, 17.6 months (9.2-34.4); OS, 24.8 months (16.5-42.3)) were longer than RASis non-users (PFS, 10.5 months (4.1-24.1); OS, 14.6 months (10.6-28.4)). The 1 year, 2 years, and 3 years' survival rates of RASis users (89.1%, 77.0%, and 65.5%) were higher than RASis non-users (70.9%, 54.0%, and 40.0%).

CONCLUSIONS

RASis usage improves the survival of patients with CCA and hypertension concurrently.

[Recommendations for the diagnosis and treatment of gout in China]

Gout is a metabolic disease resulting from the accumulation of monosodium urate (MSU) in joints, leading to crystal-induced arthritis. In China, gout is common, but there is insufficient knowledge regarding standardized criteria for the diagnosis and treatment of this condition. Based on evidence and guidelines from China and other countries, the Chinese Rheumatology Association developed standardized criteria for the diagnosis and treatment of gout in China. The purpose was to standardize gout diagnosis methods as well as treatment opportunities and strategies in order to reduce misdiagnosis, missed diagnosis, and irreversible damage.

Lipase-catalyzed ring-opening polymerization of natural compound-based cyclic monomers

The need for sustainable and environment-friendly materials has led to growing interest in the development of biodegradable polymers based on natural compounds. However, metal-based catalysts used in the polymerization process may cause concerns about the toxicity of the resultant polymers. Therefore, polymers derived from natural compounds and synthesized through the use of green catalysts are highly desirable. Lipase-catalyzed ring-opening polymerization (ROP) of biocompound-based cyclic monomers has emerged as a promising and green strategy for the design and synthesis of such polymers. In this review, we summarize reports on the use of ROP catalyzed by lipase for cyclic monomers derived from natural compounds, including bile acid- and porphyrin-based macrocycles, carbonate-based macrocycles, lactones, and cyclic anhydrides, with an emphasis on ring-closure reactions for the synthesis of cyclic monomers, the types of lipases for the ROP and the choice of reaction conditions (temperature, solvent, reaction time, etc.). Moreover, the current challenges and perspectives for the choice and reusability of lipases, ring-closure versus ring-opening reactions, monomer design, and potential applications are discussed.

SUMO specific peptidase 3 halts pancreatic ductal adenocarcinoma metastasis via deSUMOylating DKC1

In the past few decades, advances in the outcomes of patients suffering from pancreatic ductal adenocarcinoma (PDAC) have lagged behind these gained in the treatment of many other malignancies. Although the pivotal role of the SUMO pathway in PDAC has been illustrated, the underlying molecule drivers have yet to be fully elucidated. In the present study, we identified SENP3 as a potential suppressor of PDAC progression through an in vivo metastatic model. Further studies revealed that SENP3 inhibited PDAC invasion in a SUMO system dependent fashion. Mechanistically, SENP3 interacted with DKC1 and, as such, catalyzed the deSUMOylation of DKC1, which accepted SUMO3 modifiers at three lysine residues. SENP3-mediated deSUMOylation caused DKC1 instability and disruption of the interaction between snoRNP proteins, which contributed to the impaired migration ability of PDAC. Indeed, overexpression of DKC1 abated the anti-metastasis effect of SENP3, and DKC1 was elevated in PDAC specimens and associated with a poor prognosis in PDAC patients. Collectively, our findings shed light on the essential role of SENP3/DKC1 axis in the progression of PDAC.

[Artificial intelligence technology enables ultrasonography in precision diagnosisand treatment of liver diseases]

Liver disease is one of the major problems affecting human health. Ultrasound plays an important role in diagnosis and treatment of diffuse and focal liver diseases. However, conventional ultrasound evaluation is subjective and provides limited information. Artificial intelligence (AI) technology may supplement the disadvantages of conventional ultrasound and has been widely used in the field of ultrasound in liver diseases. To date, remarkable progress has been achieved for the use of AI technology in the diagnosis, assessment of therapeutic efficacy and prognosis prediction of liver diseases. This paper reviews the research progress of ultrasound image-based AI technology in the diagnosis and treatment of diffuse and focal liver diseases.

ACLP promotes activation of cancer-associated fibroblasts and tumor metastasis via ACLP-PPARγ-ACLP feedback loop in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with poor prognosis. Its fibrotic tumor microenvironment (TME) plays a crucial role in promoting tumor invasion and metastasis, which eventually leads to a dismal 5-year survival rate in PDAC patients. Aortic carboxypeptidase-like protein (ACLP) promotes tissue fibrosis in benign diseases. However, its role in cancer-associated fibrosis remains unelucidated. Here, we show that ACLP was mainly expressed in cancer-associated fibroblasts (CAFs) but not in cancer cells and highly expressed in PDAC tissues. High ACLP expression was correlated with poor overall survival. Moreover, ACLP expression in PDAC patients with liver metastases was higher than that in PDAC patients without liver metastases. By detecting activation marker expression and CAF contractility and motility, we found that ACLP promoted CAF activation in PDAC, leading to TME fibrosis. Furthermore, ACLP-activated CAFs could promote cancer cell invasion in vitro and tumor metastasis in vivo. Mechanistically, ACLP promotes the expressions of MMP1 and MMP3 in CAFs, thus promoting PDAC invasion and metastasis. Intriguingly, we identified an ACLP-PPARγ-ACLP feedback loop in PDAC CAFs. Abatement of this feedback loop might be a promising approach in CAF-targeting PDAC treatment.

Pancreatic ductal adenocarcinoma cells regulated the gemcitabine-resistance function of CAFs by LINC00460

Pancreatic ductal adenocarcinoma (PDAC) is a highly fatal malignancy with extremely poor prognosis. Gemcitabine resistance is a major challenge in the treatment of PDAC. Here, we showed that LINC00460 was associated with the response to gemcitabine both in PDAC patients and PDAC‐PDX. After knocking down LINC00460 in PDAC tumor cells, results of RNA sequencing followed by gene ontology analysis indicated that LINC00460 influenced the activity of growth factors and modified the extracellular matrix. FISH showed that LINC00460 is mostly located in the cytoplasm. Results of RNA pull‐down, LC–MS/MS, RIP, and immunoblotting confirmed that LINC00460 could directly bind to PDAP1. Furthermore, we demonstrated that LINC00460 mediated the cellular communication of PDAC tumor cells and CAFs by PDAP1/PDGFA/PDGFR signaling pathway and regulated the gemcitabine‐resistance function of CAFs, which could be reversed by treatment with a PDGFR inhibitor (crenolanib). PDAC‐PDX tumors with lower expression of LINC00460 showed a better response to gemcitabine plus crenolanib treatment. Our finding supported the application of LINC00460 in precision medicine that uses gemcitabine plus crenolanib to treat PDAC with low expression of LINC00460.

[Recommendations for diagnosis and treatment of systemic sclerosis in China]

Systemic sclerosis (SSc) is an autoimmune rheumatic disease that is characterized by skin fibrosis with multi-organ involvement. In China, the standardized diagnosis and treatment for SSc is still lacking. Based on the diagnosis criteria and guidelines from China and abroad, Chinese Rheumatology Association developed the current standardization of diagnosis and treatment for SSc. The purposes of this guideline are to standardize clinical management for SSc in China, to interpret the key evaluation tools for SSc, and to recommend therapeutic principle and strategies.

Xiaoyaosan Exerts Antidepressant-Like Effect by Regulating Autophagy Involves the Expression of GLUT4 in the Mice Hypothalamic Neurons

Many studies have proven that autophagy plays a pivotal role in the development of depression and it also affects the expression of GLUT4 in the hypothalamus. Xiaoyaosan has been shown to exert antidepressant effects in a variety of ways, but its underlying mechanism by which Xiaoyaosan regulates autophagy as well as GLUT4 in the hypothalamus remains unclear. Thus, in this study, we established a mouse model of depression induced by chronic unpredictable mild stress (CUMS), and set up autophagy blockade as a control to explore whether Xiaoyaosan exerts antidepressant effect by affecting autophagy. We examined the effects of Xiaoyaosan on behaviors exhibited during the open field test, tail suspension test and sucrose preference test, and the changes in autophagy in hypothalamic neurons as well as changes in GLUT4 and the related indicators of glucose metabolism in CUMS-induced depressive mouse model. We found that CUMS- and 3-MA-induced mice exhibited depressive-like behavioral changes, with decreased LC3 expression and increased p62 expression, suggesting decreased levels of autophagy in the mouse hypothalamus. The expression of GLUT4 was also decreased, and it was closely related to the level of autophagy through Rab8 and Rab10. Nevertheless, after the intervention of Xiaoyaosan, the above changes were effectively reversed. These results show that Xiaoyaosan can regulate the autophagy in hypothalamic neurons and the expression of GLUT4 in depressed mice.

Using Nuclear Magnetic Resonance Spectroscopy to Probe Hydrogels Formed by Sodium Deoxycholate

Hydrogels of bile acids and their salts are promising materials for drug delivery, cellular immobilization, and other applications. However, these hydrogels are poorly understood at the molecular level, and further study is needed to allow improved materials to be created by design. We have used NMR spectroscopy to probe hydrogels formed from mixtures of formic acid and sodium deoxycholate (NaDC), a common bile acid salt. By assaying the ratio of deoxycholate molecules that are immobilized as part of the fibrillar network of the hydrogels and those that can diffuse, we have found that 65% remain free under typical conditions. The network appears to be composed of both the acid and salt forms of deoxycholate, possibly because a degree of charge inhibits excessive aggregation and precipitation of the fibrils. Spin-spin relaxation times provided a molecular-level estimate of the temperature of gel-sol transition (42 °C), which is virtually the same as the value determined by analyzing macroscopic parameters. Saturation transfer difference (STD) NMR spectroscopy established that formic acid, which is present mainly as formate, is not immobilized as part of the gelating network. In contrast, HDO interacts with the network, which presumably has a surface with exposed hydrophilic groups that form hydrogen bonds with water. Moreover, the STD NMR experiments revealed that the network is a dynamic entity, with molecules of deoxycholate associating and dissociating reversibly. This exchange appears to occur preferentially by contact of the hydrophobic edges or faces of free molecules of deoxycholate with those of molecules immobilized as components of the network. In addition, DOSY experiments revealed that gelation has little effect on the diffusion of free NaDC and HDO.

[Recommendations of diagnosis and treatment of adult-onset Still's disease in China]

Adult-onset Still's disease (AOSD) is a rare systemic autoinflammatory disorder. In China, standardized diagnosis and treatment for AOSD is insufficient. Based on the evidence from China and other countries, Chinese Rheumatology Association developed standardization of diagnosis and treatment of AOSD in China. The purpose is to standardize the methods for diagnosis of AOSD, treatment strategies, and reduce misdiagnosis, missed diagnosis and irreversible damage.

Carabin Deficiency Aggravates Hepatic Ischemia-Reperfusion Injury Through Promoting Neutrophil Trafficking via Ras and Calcineurin Signaling

Neutrophil infiltration plays an important role in the initial phase of hepatic ischemia and reperfusion injury (HIRI). Despite many different key molecules that have been reported to meditate neutrophil trafficking in HIRI, the mechanism of this process has not been fully elucidated. In this study, we found that Carabin deficiency in myeloid cells (LysMCre : Carabinfl/fl) aggravated IRI-induced hepatic injury and apoptosis through increasing the infiltration of CD11b⁺Ly6G⁺ neutrophils. ImmGen Datasets further revealed that Carabin was expressed in bone marrow neutrophils (GM.BM) but was significantly downregulated in thio-induced peripheral neutrophils (GN.Thio.PC), which was consistently verified by comparing GM.BM and liver-infiltrating neutrophils induced by IRI. Mechanistically, up-regulation of Carabin in GM.BM in vitro reduced the expression levels of P-selectin, E-selectin, and αvβ3 integrin through inhibiting Ras-ERK and Calcineurin-NFAT signaling. Furthermore, blocking P-selectin, E-selectin, and αvβ3 integrin in LysMCre : Carabinfl/fl mice decreased the frequency and number of CD11b⁺Ly6G⁺ neutrophils and reversed hepatic ischemia−reperfusion damage. In conclusion, our results provide a new understanding of Carabin, such that it is expressed and functions not only in adaptive immune cells (T and B cells) but also in innate immune cells (neutrophils), contributing to the migration of neutrophils. These findings provide novel and promising therapeutic targets for the prevention of HIRI during liver transplantation or hepatic surgery.

Nitric Oxide Synthase Regulates Gut Microbiota Homeostasis by ERK-NF-κB Pathway in Shrimp

The gut microbiota is a complex group of microorganisms that is not only closely related to intestinal immunity but also affects the whole immune system of the body. Antimicrobial peptides and reactive oxygen species participate in the regulation of gut microbiota homeostasis in invertebrates. However, it is unclear whether nitric oxide, as a key mediator of immunity that plays important roles in antipathogen activity and immune regulation, participates in the regulation of gut microbiota homeostasis. In this study, we identified a nitric oxide synthase responsible for NO production in the shrimp Marsupenaeus japonicus. The expression of Nos and the NO concentration in the gastrointestinal tract were increased significantly in shrimp orally infected with Vibrio anguillarum. After RNA interference of Nos or treatment with an inhibitor of NOS, L-NMMA, NO production decreased and the gut bacterial load increased significantly in shrimp. Treatment with the NO donor, sodium nitroprusside, increased the NO level and reduced the bacterial load significantly in the shrimp gastrointestinal tract. Mechanistically, V. anguillarum infection increased NO level via upregulation of NOS and induced phosphorylation of ERK. The activated ERK phosphorylated the NF-κB-like transcription factor, dorsal, and caused nuclear translocation of dorsal to increase expression of antimicrobial peptides (AMPs) responsible for bacterial clearance. In summary, as a signaling molecule, NOS-produced NO regulates intestinal microbiota homeostasis by promoting AMP expression against infected pathogens via the ERK-dorsal pathway in shrimp.

HNRNPC impedes m6A-dependent anti-metastatic alternative splicing events in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a malignancy with poor prognosis due to early metastasis. The aberrant N6-methyladenosine (m6A) RNA modification has emerged as an important mechanism in cancer progression and metastasis, but its role in PDAC remained largely unknown. Here, we demonstrated that an m6A regulator, heterogeneous nuclear ribonucleoprotein C (HNRNPC), modulated alternative splicing events to promote PDAC metastasis. In clinical PDAC tissues, high expression of HNRNPC was correlated with metastasis, resulting in poor prognosis in PDAC patients. Knockdown of HNRNPC significantly reduced PDAC cell invasion in vitro and metastasis in vivo. In contrast, overexpression of HNRNPC provoked malignant phenotypes of PDAC cells. Mechanistically, HNRNPC antagonized the anti-metastatic isoform of TAF8 (TAF8L) but increased the pro-metastatic alternative splicing isoform of TAF8 (TAF8S). Mutation of the m6A-site of TAF8 attenuated the interaction between HNRNPC and TAF8 transcript, leading to the decrease of TAF8S. Furthermore, experimental manipulation of the anti-metastasis splicing isoform TAF8L revealed that splice isoform switching of TAF8 is crucial for PDAC metastasis. In conclusion, our findings demonstrate the essentiality of HNRNPC-mediated alternative splicing events that impinges on metastatic PDAC.

Smart microneedle patches for rapid, and painless transdermal insulin delivery

Insulin administration at mealtimes for the control of postprandial glucose is a major part of basal-bolus insulin therapy; however, painful subcutaneous (SC) injections lead to poor patient compliance. The microneedle (MN) patch, which allows painless transdermal drug delivery, is a promising substitute; however, it remains a big challenge to deliver insulin as rapidly as by SC injection. Here a novel MN patch is designed in which the MNs are coated with insulin/poly-l-glutamic acid (PGA) layer-by-layer (LBL) films at pH 3.0. This coating is pH-sensitive because the net charge of insulin turns from positive to negative when the pH increases from 3.0 to 7.4. As a result, when transferred to pH 7.4 media, e.g., when inserted into skin, the coating dissociates instantly and releases insulin rapidly. A brief epidermal application (<1 min) of the coated MNs is enough for complete film dissociation. More importantly, the coated MN patch exhibits a pharmacokinetic and a pharmacodynamic profile comparable to that of insulin administrated by SC injection, suggesting the coated MN patch can deliver insulin as rapidly as the SC injection. In addition, the patch exhibits excellent biocompatibility and storage stability. The new MN patch is expected to become a painless, convenient method for the control of postprandial glucose.

Functional fillers for dental resin composites

Dental resin composites (DRCs) are popular materials to repair caries. Although various types of DRCs with different characteristics have been developed, restoration failures still exist. Bulk fracture and secondary caries have been considered as main causes for the failure of composites restoration. To address these problems, various fillers with specific functions have been introduced and studied. Some fillers with specific morphologies such as whisker, fiber, and nanotube, have been used to increase the mechanical properties of DRCs, and other fillers releasing ions such as Ag⁺, Ca²⁺, and F^-, have been used to inhibit the secondary caries. These functional fillers are helpful to improve the performances and lifespan of DRCs. In this article, we firstly introduce the composition and development of DRCs, then review and discuss the functional fillers classified according to their roles in the DRCs, finally give a summary on the current research and predict the trend of future development.

[Recommendations of diagnosis and treatment of gout in China]

Gout is a crystal associated arthritis caused by monosodium urate (MSU) accumulating in joint, and it belongs to metabolic rheumatic disease. In China, gout is common but it is insufficient for education of standardized diagnosis and treatment for gout. Based on the evidence and guidelines from China and other countries, Chinese gout Collaborative Research Group developed standardization of diagnosis and treatment of gout in China. The purpose is to standardize the methods for diagnosis of gout, treatment opportunity and strategies in order to reduce misdiagnosis, missed diagnosis and irreversible damage.

[Study on fibrosis changes in the lungs of mice caused by repeated inhalation of polyhexamethyleneguaidine disinfectant]

Objective: To explore the lung damage caused by repeated inhalation of polyhexamethyleneguanidine (PHMG) disinfectant aerosol and the corresponding toxicological characteristics. Methods: Thirty four-week-old mice of C57BL/6N strain were randomly divided into three groups, the control group, low-dose group, and high-dose group. Each group had 5 male mice and 5 female mice. Lab II-level purified water was used in the control group. The PHMG disinfectant aerosol was generated by using the ultrasonic atomization of the aqueous solution containing PHMG. The PHMG concentrations in the low-and high-dose groups were 0.1 mg/ml (0.01%) and 1 mg/ml (0.1%), respectively. The concentration of PHMG in the post-chemical exposure room was 1.03 mg/m(3) and 9.09 mg/m(3) according to the air sampler analysis. The experimental mice were exposed to the PHMG in dynamic respiratory exposure mode for 4 hours every day in 21 days. After 21-day exposure, bronchia alveolus lung fluids (BALFs) were used to evaluate the inflammatory cells in the lungs, and pathological evaluation, special staining and immunohistochemical methods were further performed to evaluate the key indicators of pulmonary fibrosis. Results: Compared to the control group, the body weight of mice in the high-dose group was significantly decreased (P<0.05), while that of mice in the low-dose group did not significantly differ (P>0.05). The number of inflammatory cells in BALFs of low-dose exposed mice was slightly reduced, and the lung tissue pathology began to show lung damage with early fibrosis symptoms (P<0.05). The pathological examination of mice in the high-dose group showed changes in pulmonary fibrosis. Immunohistochemical staining showed that pulmonary fibrosis marker, α-SMA, was significantly increased in low-dose group and high-dose group (P<0.05). Conclusion: The repeated inhalation of PHMG disinfectant could cause lung damage such as pulmonary fibrosis in mice. It could suggest that special warnings should be given to this common disinfectant and respiratory protection measures should be adopted during industrial production and daily use.

MFAP5 facilitates the aggressiveness of intrahepatic Cholangiocarcinoma by activating the Notch1 signaling pathway

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver cancer. The dismal outcome of ICC patients is due to lack of early diagnosis, the aggressive biological behavior of ICC and the lack of effective therapeutic options. Early diagnosis and prognosis of ICC by non-invasive methods would be helpful in providing valuable information and developing effective treatment strategies.

METHODS

Expression of microfibrillar-associated protein 5 (MFAP5) in the serum of ICC patients was detected by ELISA. Human ICC specimens were immunostained by MFAP5 antibodies. The growth rate of human ICC cell lines treated with MFAP5 or MFAP5 shRNAs was examined by CCK8 and colony formation assays. Cell cycle analysis was performed with PI staining. The effect of MFAP5 inhibition was assessed by xenograft models in nude mice. RNA-seq and ATAC-seq analyses were used to dissect the molecular mechanism by which MFAP5 promoted ICC aggressiveness.

RESULTS

We identified MFAP5 as a biomarker for the diagnosis and prognosis of ICC. Upregulated MFAP5 is a common feature in aggressive ICC patients' tissues. Importantly, MFAP5 level in the serum of ICC patients and healthy individuals showed significant differential expression profiles. Furthermore, we showed that MFAP5 promoted ICC cell growth and G1 to S-phase transition. Using RNA-seq expression and ATAC-seq chromatin accessibility profiling of ICC cells with suppressed MFAP5 secretion, we showed that MFAP5 regulated the expression of genes involved in the Notch1 signaling pathway. Furthermore, FLI-06, a Notch signaling inhibitor, completely abolished the MFAP5-dependent transcriptional programs.

CONCLUSIONS

Raised MFAP5 serum level is useful for differentiating ICC patients from healthy individuals, and could be helpful in ICC diagnosis, prognosis and therapies.

EYA4 inhibits hepatocellular carcinoma by repressing MYCBP by dephosphorylating β-catenin at Ser552

Hepatocellular carcinoma (HCC) is one of the most common malignancies and the fourth leading cause of cancer-related death worldwide. Our previous study showed that EYA4 functioned by suppressing growth of HCC tumor cells, but its molecular mechanism is still not elucidated. Based on the results of gene microassay, EYA4 was inversely correlated with MYCBP and was verified in human HCC tissues by immunohistochemistry and western blot. Overexpressed and KO EYA4 in human HCC cell lines confirmed the negative correlation between EYA4 and MYCBP by qRT-PCR and western blot. Transfected siRNA of MYCBP in EYA4 overexpressed cells and overexpressed MYCBP in EYA4 KO cells could efficiently rescue the proliferation and G2/M arrest effects of EYA4 on HCC cells. Mechanistically, armed with serine/threonine-specific protein phosphatase activity, EYA4 reduced nuclear translocation of β-catenin by dephosphorylating β-catenin at Ser552, thereby suppressing the transcription of MYCBP which was induced by β-catenin/LEF1 binding to the promoter of MYCBP. Clinically, HCC patients with highly expressed EYA4 and poorly expressed MYCBP had significantly longer disease-free survival and overall survival than HCC patients with poorly expressed EYA4 and highly expressed MYCBP. In conclusion, EYA4 suppressed HCC tumor cell growth by repressing MYCBP by dephosphorylating β-catenin S552. EYA4 combined with MYCBP could be potential prognostic biomarkers in HCC.

[Clinical applications of intelligent pressure control flexible ureteroscope for the treatment of renal calculi ≤2 cm]

Objective: To evaluate the effectiveness and safety of intelligent pressure control flexible ureteroscope for management of renal stones ≤2 cm. Methods: The clinical data of 267 cases of renal calculi treated with flexible ureteroscope lithotripsy at Department of Urology, Ganzhou People's Hospital from June 2015 to December 2017 were analyzed retrospectively. There were 129 male and 138 female patients, with a mean age of 51.2 years (ranging from 19 to 76 years). Among them, 145 patients underwent intelligent pressure control flexible ureteroscope (intelligent control group) and 122 patients underwent flexible ureteroscope ordinary (ordinary group). The t test, χ² test or Fisher exact test were used for statistical analysis. The success rate of stone seeking, the stone free rates, the incidence of complications, the average operation time, the average hospital stay after operation were compared between the two groups. Results: The average mean operative time of the patients with intelligent control group was (26.17 ± 8.64) minutes, significantly shorter than (47.23±18.35) minutes of the ordinary group (t=1.968, P=0.000). The stone free rate of the patients with intelligent control group was 97.2%, it was higher than 86.0% of ordinary group (χ²=0.069, P=0.004). The complication rate of the patients with intelligent control group was 2.7%, which was significantly shorter than 18.0% of the ordinary group (χ²=17.586, P=0.000). However, there was no significant difference between the two groups in the success rate of stone seeking and postoperative hospital stay (P>0.05). Conclusion: Intelligent controlled pressure ureteral flexible ureteroscope has the advantages of short operation time, high stone free rate and less complications in the treatment of renal calculi ≤2 cm compared with flexible ureteroscope ordinary.

The C/EBPβ-LINC01133 axis promotes cell proliferation in pancreatic ductal adenocarcinoma through upregulation of CCNG1

Long non-coding RNAs (lncRNAs) are emerging as important regulators and prognostic markers of multiple cancers. Our aim was to determine functional involvement of lncRNAs in pancreatic ductal adenocarcinoma (PDAC). In this study, we report that LINC01133 expression is higher in PDAC tissues compared to adjacent non-cancerous tissues, and this overexpression is associated with poorer prognosis among the patients. In vitro, a knockdown of LINC01133 substantially decreased PDAC cell proliferation. Tumorigenicity of PDAC cells with the LINC01133 knockdown was significantly impaired in a xenograft model assay. Moreover, we determined that CCAAT/enhancer-binding protein β (C/EBPβ) positively regulates LINC01133 expression by binding to the response elements within the LINC01133 promoter. Higher expression of C/EBPβ was observed in PDAC tissues, and this overexpression was also associated with the poorer prognosis. Furthermore, the LINC01133 knockdown decreased cyclin G1 (CCNG1) expression. Overexpression of CCNG1 attenuated the LINC01133 silencing-induced impairment of proliferation in PDAC cells. In summary, our findings revealed that the C/EBPβ-LINC01133 axis performs an oncogenic function in PDAC by activating CCNG1, which may serve as a prognostic biomarker or a therapeutic target in PDAC.

Bile Acid-Based Drug Delivery Systems for Enhanced Doxorubicin Encapsulation: Comparing Hydrophobic and Ionic Interactions in Drug Loading and Release

Doxorubicin (Dox) is a drug of choice in the design of drug delivery systems directed toward breast cancers, but is often limited by loading and control over its release from polymer micelles. Bile acid-based block copolymers present certain advantages over traditional polymer-based systems for drug delivery purposes, since they can enable a higher drug loading via the formation of a reservoir through their aggregation process. In this study, hydrophobic and electrostatic interactions are compared for their influence on Dox loading inside cholic acid based block copolymers. Poly(allyl glycidyl ether) (PAGE) and poly(ethylene glycol) (PEG) were grafted from the cholic acid (CA) core yielding a star-shaped block copolymer with 4 arms (CA-(PAGE- b-PEG)₄) and then loaded with Dox via a nanoprecipitation technique. A high Dox loading of 14 wt % was achieved via electrostatic as opposed to hydrophobic interactions with or without oleic acid as a cosurfactant. The electrostatic interactions confer a pH responsiveness to the system. 50% of the loaded Dox was released at pH 5 in comparison to 12% at pH 7.4. The nanoparticles with Dox loaded via hydrophobic interactions did not show such a pH responsiveness. The systems with Dox loaded via electrostatic interactions showed the lowest IC₅₀ and highest cellular internalization, indicating the pre-eminence of this interaction in Dox loading. The blank formulations are biocompatible and did not show cytotoxicity up to 0.17 mg/mL. The new functionalized star block copolymers based on cholic acid show great potential as drug delivery carriers.

BTG2 Is Down-Regulated and Inhibits Cancer Stem Cell-Like Features of Side Population Cells in Hepatocellular Carcinoma

BACKGROUND

Our previous study found that B cell translocation gene 2 (BTG2) was hyper-methylated and down-regulated in side population (SP) cells of hepatocellular carcinoma (HCC) cell line. However, its clinical significances and biological impacts on HCC SP cells remained unclear.

AIMS

To investigate the prognostic value of BTG2 gene in HCC and its influences on cancer stem cells (CSCs)-like traits of HCC cell line SP cells.

METHODS

BTG2 expression in human HCC and adjacent non-cancerous tissues was detected by immunohistochemical staining and quantitative real-time PCR, and also obtained from GEO and TCGA data. Its prognostic values were assessed. Its biological influences on HCC cell line SP cells were evaluated using cell viability, cell cycle, plate clone-forming assay, and chemoresistance in vitro and tumorigenicity in vivo.

RESULTS

BTG2 expression was significantly suppressed in human HCC compared to adjacent non-cancerous tissues. BTG2 expression was correlated with TNM stage, tumor size and vascular invasion. Lower expression of BTG2 was associated with poorer overall survival and disease-free survival. In vitro, overexpression of BTG2 substantially suppressed cell proliferation and accumulation of HCC cell line SP cells in G0/G1 phase. Colony formation ability was markedly suppressed by BTG2 overexpression. Moreover, sensitivity of HCC cell line SP cells to 5-fluorouracil was substantially increased by overexpression of BTG2. Furthermore, tumorigenicity of HCC cell line SP cells transfected with BTG2 plasmids was significantly reduced in vivo.

CONCLUSIONS

BTG2 gene could regulate the CSC-like traits of HCC cell line SP cells, and it represented as a molecular prognostic marker for HCC.

[DNT cell inhibits the growth of pancreatic carcinoma via NKG2D and MICA pathway in vivo]

Objective: To investigate the effects of natural killer group 2 member D (NKG2D) and its ligands major histocompatibility complex class Ⅰ chain-related molecules A(MICA) on DNT cell killing pancreatic carcinoma. Methods: Antibodies adsorption was used to separate DNT cell from human peripheral blood. Human pancreatic tumor models were established via implanting BXPC-3 cells into nude mice, and then mice were randomly divided mice into 3 groups, blank group, gemcitabine group and DNT group. Mice weights and mice tumor volumes were measured every 5 days. After 40 days mice were euthanized at cervical dislocation method. Tumor weights were measured. Relative tumor volume and tumor inhibition rate were calculated. Western blot and qPCR were used to detect the expressions of NKG2D and MICA in the transplanted tumors of the three groups. Results: The blank group tumor volume and weight of blank group were significantly larger than those of gemcitabine group and DNT group (858.7±35.7 mg, 251.1±19.7 mg, 278.5±17.3 mg, P<0.001), but there were no significantly difference between DNT group and gemcitabine group. The tumor inhibition rate of gemcitabine and DNT cell were 40.4% and 35.5%. Western blot and qPCR showed that MICA mRNA and protein levels in blank group were significantly higher than those in DNT group (P=0.001, P=0.003). NKG2D mRNA and protein levels in blank group were significantly lower than those in DNT cells group (P<0.001, P=0.001). Conclusion: DNT cell can significantly inhibit the growth of pancreatic carcinoma in vivo, and the mechanism may be involved in abnormal expressions of MICA and NKG2D.

"Bitter-Sweet" Polymeric Micelles Formed by Block Copolymers from Glucosamine and Cholic Acid

Natural compounds glucosamine and cholic acid have been used to make acrylic monomers which are subsequently used to prepare amphiphilic block copolymers by reversible addition-fragmentation chain transfer (RAFT) polymerization. Despite the striking difference in polarity and solubility, three diblock copolymers consisting of glucosamine and cholic acid pendants with different hydrophilic and hydrophobic chain lengths have been synthesized without the use of protecting groups. They are shown to self-assemble into polymeric micelles with a "bitter" bile acid core and "sweet" sugar shell in aqueous solutions, as evidenced by dynamic light scattering and transmission electron microscopy. The critical micelle concentration varies with the hydrophobic/hydrophilic ratio, ranging from 0.62 to 1.31 mg/L. Longer chains of polymers induced the formation of larger micelles in range of 50-70 nm. These micelles can solubilize hydrophobic compounds such as Nile Red in aqueous solutions. Their loading capacity mainly depends upon the hydrophobic/hydrophilic ratio of the polymers, and may be also related to the length of the hydrophilic block. These polymeric micelles allowed for a 10-fold increase in the aqueous solubility of paclitaxel and showed no cytotoxicity below the concentration of 500 mg/L. Such properties make these polymeric micelles interesting reservoirs for hydrophobic molecules and drugs for biomedical applications.

Self-Assembly of a Bile Acid Dimer in Aqueous Solutions: From Nanofibers to Nematic Hydrogels

A mixture of a cholic acid dimer with a secondary amine group and formic acid at a molar ratio of 1/1 is regarded as an organic salt, and it self-assembles in aqueous solutions to form monodisperse nanofibers. The nanofibers are separated at low concentrations of the mixture but entangle with each other at high concentrations to form well-dispersed and randomly arranged 3D fibrous networks. Above the minimum gelation concentration of the dimer, the fibrous network is strong enough to gelate the aqueous solutions to form a hydrogel. Hydrogels obtained from the dimer salt at a lower concentration are isotropic and show extinction between crossed polarizers in the polarizing microscope, whereas they become anisotropic (i.e., nematic hydrogels) upon increasing the dimer salt concentration or under physical stirring. The parallel arrangement of nanofibers from randomly directed fibrous networks may be responsible for the formation of such nematic hydrogels.

Oxygen Inhibition in Dental Resins

Oxygen inhibits free radical polymerization and yields polymers with uncured surfaces. This is a concern when thin layers of resin are being polymerized, or in circumstances where conventional means of eliminating inhibition are inappropriate. In this study, we tested the hypothesis that viscosity, filler content, and polymerization temperature modify oxygen diffusion in the resin or the reactivity of radical species, and affect the degree of conversion near the surface. Confocal Raman micro-spectroscopy was used to measure monomer conversion from the surface to the bulk of cured resins. Increased viscosity was shown to limit oxygen diffusion and increase conversion near the surface, without necessarily modifying the depth of inhibition. The filler material was shown to increase, simultaneously, oxygen diffusivity and the viscosity of the resin, which have opposite effects on conversion. Polymerization at a temperature above ~ 110°C was shown to eliminate oxygen inhibition.

Facile Assembly of Large-Area 2D Microgel Colloidal Crystals Using Charge-Reversible Substrates

2D colloidal crystals (CCs) have important applications; however, the fabrication of large-area, high-quality 2D CCs is still far from being trivial, and the fabrication of 2D microgel CCs is even harder. Here, we have demonstrated that they can be facilely fabricated using charge-reversible substrates. The charge-reversible substrates were prepared by modification with amino groups. The amino groups were then protected by amidation with 2,2-dimethylsuccinic anhydride. At acidic pH, the surface charge of the modified substrate will change from negative to positive as a result of the hydrolysis of the amide bonds and the regeneration of the amino groups. 2D microgel CCs can be simply fabricated by applying a concentrated microgel dispersion on the modified substrate. The negatively charged surface of the substrate allows the negatively charged microgel spheres, especially those close to the substrate, to self-assemble into 3D CCs. With the gradual hydrolysis of the amide bonds and the charge reversal of the substrate, the first 111 plane of the 3D assembly is fixed in situ on the substrate. The resulting 2D CC has a high degree of ordering because of the high quality of the parent 3D microgel CC. Because large-area 3D microgel CCs can be facilely fabricated, this method allows for the fabrication of 2D CCs of any size. Nonplanar substrates can also be used. In addition, the interparticle distance of the 2D array can be tuned by the concentration of the microgel dispersion. Besides rigid substrates (such as glass slides, quartz slides, and silicon wafers), flexible polymer films, including polyethylene terephthalate and poly(vinyl chloride) films, were also successfully used as substrates for the fabrication of 2D microgel CCs.

Self-Healing Supramolecular Hydrogels Based on Reversible Physical Interactions

Dynamic and reversible polymer networks capable of self-healing, i.e., restoring their mechanical properties after deformation and failure, are gaining increasing research interest, as there is a continuous need towards extending the lifetime and improving the safety and performance of materials particularly in biomedical applications. Hydrogels are versatile materials that may allow self-healing through a variety of covalent and non-covalent bonding strategies. The structural recovery of physical gels has long been a topic of interest in soft materials physics and various supramolecular interactions can induce this kind of recovery. This review highlights the non-covalent strategies of building self-repairing hydrogels and the characterization of their mechanical properties. Potential applications and future prospects of these materials are also discussed.

Thermo- and pH-Responsive Copolymers Bearing Cholic Acid and Oligo(ethylene glycol) Pendants: Self-Assembly and pH-Controlled Release

A family of block and random copolymers of norbornene derivatives bearing cholic acid and oligo(ethylene glycol) pendants were prepared in the presence of Grubbs' catalyst. The phase transition temperature of the copolymers in aqueous solutions may be tuned by the variation of comonomer ratios and pH values. Both types of copolymers formed micellar nanostructures with a hydrophilic poly(ethylene glycol) shell and a hydrophobic core containing cholic acid residues. The micellar size increased gradually with increasing pH due to the deprotonation of the carboxylic acid groups. These micelles were capable of encapsulating hydrophobic compounds such as Nile Red (NR). A higher hydrophobicity/hydrophilicity ratio in both copolymers resulted in a higher loading capacity for NR. With similar molecular weights and monomer compositions, the block copolymers showed a higher loading capacity for NR than the random copolymers. The NR-loaded micelles exhibited a pH-triggered release behavior. At pH 7.4 within 96 h, the micelles formed by the block and random of copolymers released 56 and 97% NR, respectively. Therefore, these micelles may have promise for use as therapeutic nanocarriers in drug delivery systems.

Glucosamine-Anchored Graphene Oxide Nanosheets: Fabrication, Ultraviolet Irradiation, and Electrochemical Properties

A biofunctionalized graphene oxide (GO) nanosheet with improved physicochemical properties is useful for electrocatalysis and sensor development. Herein, a new class of functionalized GO with a chemically anchored biomolecule glucosamine is developed. Structural and chemical analyses confirm the glucosamine anchoring. Ultraviolet irradiation transforms the surface chemistry of GO. Glucosamine-anchored GO nanosheets exhibit improved cyclic voltammetric and amperometric sensing activity toward the model redox probe, ruthenium(II) and N-acetylneuraminic acid, respectively. The biomolecular anchoring and ultraviolet irradiation helped to tune and enhance the properties of GO, which may find multiple applications in optimizing sensor platforms.

Swelling-induced surface instability patterns guided by pre-introduced structures

Swelling-induced, spontaneously generated surface instability patterns in substrate-attached hydrogel films can be harnessed for advanced applications, however, methods to control their formation and morphology are missing. Here we propose that their generation may be guided by intentionally pre-introduced line structures. While uniform gel films produce irregular polygonal instability patterns, instability patterns generated in pre-patterned films with hexagonal line structures are regular hexagons with long-range order. The pre-introduced line structures act as defects in the generation of the surface instability patterns, which determine the position of the creases, regulate their rearrangement and determine their final morphology. The contrast between the pre-introduced structures and the surrounding area should be high enough for the pre-introduced structures to act as defects. Only when the characteristic wavelength of the pre-introduced pattern matches with the one of the gel film, perfect hexagonal patterns can be obtained. The gel films with uniform topographic features may find various advanced applications.

Thermoresponsiveness of copolymers bearing cholic acid pendants induced by complexation with β-cyclodextrin

Copolymers of N-alkylacrylamides and methacrylate bearing cholic acid pendant groups were synthesized via radical polymerization. The cholic acid pendant groups of such copolymers can form complexes with β-cyclodextrin, and the effect of complexation on their thermoresponsive properties was studied. The phase transition temperatures (transition from hydrophilic to hydrophobic state) of the copolymers gradually increase with the addition of β-cyclodextrin, due to the complexation of the cholic acid guest with the β-cyclodextrin host. The increase of the phase transition temperature may be reversed by the addition of a competing guest molecule, potassium 1-adamantylcarboxylate. The host-guest complexation provides a straightforward way to vary the thermoresponsive properties of such copolymers.

Invertible vesicles and micelles formed by dually-responsive diblock random copolymers in aqueous solutions

Dually responsive diblock random copolymers poly(nPA0.8-co-DEAEMA0.2)-block-poly(nPA0.8-co-EA0.2) were made from N-n-propylacrylamide (nPA), 2-(diethylamino)ethyl methacrylate (DEAEMA) and N-ethylacrylamide (EA) via reversible addition-fragmentation chain transfer (RAFT) polymerization. Copolymers of different block length ratios, poly(nPA28-co-DEAEMA7)-block-poly(nPA29-co-EA7) (P1) and poly(nPA28-co-DEAEMA7)-block-poly(nPA70-co-EA18) (P2), self-assemble into vesicles and micelles, responding to external stimuli in aqueous solutions, and both show "schizophrenic" inversion behavior when the pH and temperature are varied. The relative lengths of the two blocks are shown to affect the self-assembly of amphiphilic diblock copolymers. P1 has a similar length for both blocks and forms spherical vesicles with the first block poly(nPA29-co-EA7) as the membrane inner layer at pH 7 and 37 °C (above the cloud point of the more hydrophobic block, CP1), while spherical micelle-like aggregates are obtained at pH 10 and 25 °C (above CP1) with the second block poly(nPA28-co-DEAEMA7) as the core. In comparison, P2 has a different block length ratio (1 : 3, thus a much longer second block) and forms spherical micelles above CP1 at both pH 7 (the second block as the core) and pH 10 (the first block as the core). Further aggregation was observed by heating the polymer solution above the cloud point of the more hydrophilic block (CP2). The variation of the length and chemical composition of the blocks allows the tuning of the responsiveness of the block copolymers toward both pH and temperature and determines the formation of either micelles or vesicles during the aggregation.

Block and random copolymers bearing cholic acid and oligo(ethylene glycol) pendant groups: aggregation, thermosensitivity, and drug loading

A series of block and random copolymers consisting of oligo(ethylene glycol) and cholic acid pendant groups were synthesized via ring-opening metathesis polymerization of their norbornene derivatives. These block and random copolymers were designed to have similar molecular weights and comonomer ratios; both types of copolymers showed thermosensitivity in aqueous solutions with similar cloud points. The copolymers self-assembled into micelles in water as shown by dynamic light scattering and transmission electron microscopy. The hydrodynamic diameter of the micelles formed by the block copolymer is much larger and exhibited a broad and gradual shrinkage from 20 to 54 °C below its cloud point, while the micelles formed by the random copolymers are smaller in size but exhibited some swelling in the same temperature range. Based on in vitro drug release studies, 78% and 24% paclitaxel (PTX) were released in 24 h from micelles self-assembled by the block and random copolymers, respectively. PTX-loaded micelles formed by the block and random copolymers exhibited apparent antitumor efficacy toward the ovarian cancer cells with a particularly low half-maximal inhibitory concentration (IC50) of 27.4 and 40.2 ng/mL, respectively. Cholic acid-based micelles show promise as a versatile and potent platform for cancer chemotherapy.

Switchable vesicles formed by diblock random copolymers with tunable pH- and thermo-responsiveness

The thermo-responsiveness of polymers in aqueous media can be tuned by the choice of comonomers used in the synthesis of block copolymers made of random sequences of the same comonomers but of different molar ratios. The same synthetic approach may be applied to other stimuli and we have made diblock random copolymers with both pH- and thermo-responsiveness and studied the formation of vesicles whose membrane core and coronas may be inverted in aqueous media. Sequential reversible addition-fragmentation chain transfer (RAFT) polymerization was used to prepare well-defined block copolymers in the form of AnBm-b-ApCq, where A, B, and C are N-n-propylacrylamide (nPA), 2-(diethylamino)ethyl methacrylate (DEAEMA), and N-ethylacrylamide (EA), respectively. This polymer shows interesting "schizophrenic" behavior in aqueous solutions. Both blocks are thermo-responsive, and one block is pH-responsive in which the tertiary amine group of DEAEMA may be protonated at a lower pH. A molecularly dissolved polymer is obtained at neutral pH and ambient temperature. At pH 7 and 37 °C, the polymer self-assembles into vesicles with the poly(nPA0.8-co-EA0.2) block as the membrane core (mean hydrodynamic diameter of the vesicles Dh = 148 nm). In an alkaline medium (pH 10) at 25 °C, the membrane core and the coronas of the vesicles are inverted with poly(nPA0.8-co-DEAEMA0.2) block forming the core (Dh = 60 nm). In addition, two-step phase transitions are observed in both alkaline and neutral solutions corresponding to the cloud points of the individual blocks. Here, the random nature of the blocks allows fine-tuning the thermo-responsiveness based solely on lower critical solution temperatures and its combination with pH-sensitivity provides vesicles with switchable membrane core and corona in aqueous solution.

Aggregation behavior of pegylated bile acid derivatives

Bile acids are amphiphilic endogenous steroids that act as anionic surfactants in the digestive tract and aggregate in aqueous solutions. Nonionic surfactants were synthesized by grafting poly(ethylene glycol) chains of various lengths (pegylation) to three bile acids (lithocholic, deoxycholic, and cholic acid) using anionic polymerization. The aggregation properties of the derivatives were studied with viscosity measurements and light scattering as well as with steady-state and time-resolved fluorescence techniques, and the aggregates were visualized by transmission electron microscopy to elucidate the effect of pegylation on the aggregation process. The fluorescence results showed a good correlation with the capacity of the bile acid derivatives to solubilize a hydrophobic drug molecule. The solubilization of ibuprofen depends on the length and the number of grafted PEG chains, and the solubilization efficiency increases with fewer PEG chains on the bile acid. The results indicate their potential for use in the design of new bile acid-based drug-delivery systems.

Fractal structures of the hydrogels formed in situ from poly(N-isopropylacrylamide) microgel dispersions

Dispersions of poly(N-isopropylacrylamide) (PNIPAM) microgel thermally gel in the presence of inorganic salts. The in situ-formed hydrogels, with a network of soft particles, represent a new type of colloidal gels. Here, their fractal structures were determined by rheological measurements, using the models of both Shih et al. and Wu and Morbidelli. According to the definition of Shih et al., the colloidal PNIPAM gels fall into the strong-link regime. Yet the calculated fractal dimension of the floc backbone, x, yielded unrealistic negative values, suggesting this model is inapplicable for the present system. The Wu-Morbidelli model gives physically sounder results. According to this model, the strengths of the inter- and intrafloc links are comparable, and the in situ-formed gels are in the transition regime. The fractal dimension, d(f), of the hydrogel decreases from ∼2.5 to ∼1.8 when the heating temperature increases from 34 to 40 °C. The d(f) values suggest different aggregation mechanisms at different temperatures, that is, a reaction-limited one accompanied by rearrangement at low temperature, a typical reaction-limited one at the intermediate temperature, and a diffusion-limited one at high temperature. With increasing salt concentration, the d(f) of the hydrogel decreases from ∼2.1 to ∼1.7, suggesting the aggregation mechanism changes from reaction-limited to diffusion-limited. The effects of both temperature and salt concentration can be explained by the changes in the interactions among the microgel particles. The thermogellable PNIPAM microgel dispersions may serve as a model system for the study of heat-induced gelation of globular proteins.

Multi-responsive properties of a poly(ethylene glycol)-grafted alternating copolymers of distyrenic monomer with maleic anhydride

A series of amphiphilic copolymers were synthesized by reversible addition-fragmentation chain transfer cyclocopolymerization of a styrenic monomer with maleic anhydride followed by grafting methoxy poly(ethylene glycol) onto the anhydride groups of the polymer chain. These amphiphilic graft copolymers exhibit multiple responsiveness toward temperature, pH, and selected cations in aqueous solutions. The cloud points (CP) of the graft copolymers increase with increasing length of the side chains and with increasing pH value of the solution. The addition of KCl and LiCl to the solutions had a salting-out effect lowering the CPs of the graft copolymers. The addition of NaCl, however, first raised the CP due to the complexation of the crown ether with Na(+) and then lowered the CP. The light scattering results confirmed an increase in phase transition temperature at lower concentrations of NaCl (5 and 10 mM) and then a decrease at a higher concentration of the sodium salt (100 mM).

Aggregation and thermoresponsive properties of new star block copolymers with a cholic acid core

Poly(allyl glycidyl ether) (PAGE) and poly(ethylene glycol) (PEG) blocks were sequentially grown via anionic polymerization to form four block copolymer arms on a cholic acid (CA) core, yielding star block copolymers (CA(AGE(8)-b-EG(n))(4)) with low polydispersities (ca. 1.05). The introduction of PAGE segments into CA(PEG)(4) significantly reduced their crystallinity. The polymers can aggregate in water at room temperature above their critical aggregation concentration. The copolymers are thermoresponsive; their behavior in aqueous solutions was studied by the use of UV-visible spectroscopy, dynamic light scattering, and transmission electron microscopy. Their cloud points vary from 13 to 55 °C with increasing length of the PEG segments. Double thermoresponsive behavior was observed with short PEG segments because of a two-step transition process: small micelles are formed upon heating and then further aggregate into micellar clusters through the association of PEG chains.

NMR imaging of chitosan and carboxymethyl starch tablets: swelling and hydration of the polyelectrolyte complex

The hydration and swelling properties of the tablets made of chitosan, carboxymethyl starch, and a polyelectrolyte complex of these two polysaccharides have been studied by NMR imaging. We studied the effect of pH and ionic strength on the swelling of the tablets and on the diffusion of fluid into the tablets in water and simulated physiological fluids. The pH value of the fluids exerts a more significant effect than their ionic strengths on the swelling of the tablets. The tablets are compared also with those made of cross-linked high amylose starch. The formation of complex helps to keep the integrity of the tablets in various media and render a slow and restricted swelling similar to that of the tablets of the cross-linked high amylase starch, which is significantly lower than the swelling of chitosan and of carboxymethyl starch. The capacities to modulate the release rate of drugs in different media are discussed by comparing the matrices and evaluating the preparation process of the complex. A sustained release of less soluble drugs such as aspirin in gastrointestinal fluids can be provided by the complex, due to the ionic interaction and hydrogen bonding between the drug and the biopolymer complex.

Thermosensitivity of bile acid-based oligo(ethylene glycol) stars in aqueous solutions

Amphiphilic star-shaped oligo(ethylene glycol)s with a hydrophobic bile acid core and varying number of hydrophilic arms have been made. Their thermal behavior in aqueous solutions depends on the number rather than the length of the arms. The two-armed lithocholate derivative showed the strongest tendency for association and exhibited the lowest cloud point (79 °C) of the oligomers made, as well as another phase separation at a lower temperature (31 °C). The "double thermosensitivity" arising both from the salt-dependent LCST of the oligo(ethylene glycol) segments and the temperature-responsive self-assembly of amphiphilic bile acid derivative provides an interesting path in the design of bile acid-based smart materials.

1,2,3-Triazole-containing molecular pockets derived from cholic acid: the influence of structure on host-guest coordination properties

Two cholic acid-containing trimers with 1,2,3-triazole groups close to the connecting point ("top") and at the end of the cholic acid arms ("bottom") were synthesized. These molecules are able to form hydrophobic pockets and solubilize pyrene and other hydrophobic molecules in polar media due to the facial amphiphilicity of cholic acid. Heavy metal ions such as Cu(II) can also be coordinated by the 1,2,3-triazole groups, as shown by EPR spectroscopy. Due to the vicinity of metal ions and pyrene in the pockets, the fluorescence of pyrene is quenched. However, the position of the 1,2,3-triazole groups has a crucial influence on the metal ion complexation. The trimer with 1,2,3-triazole groups at the top is found to bind metal ions more effectively and gives rise to a significantly enhanced fluorescence quenching efficiency. Here, the metal ions act as one tridentate chelating agent, while the triazoles on the bottom rather behave as single entities without any cooperativity in binding to the metal. In the latter case, the quenching effect is reduced considerably despite the fact that both trimers are able to bind Cu(II). This indicates that the specific and strong binding of Cu(II) at the top leads to closer spatial proximity between metal ion and pyrene when compared to the Cu(II) bound on the bottom.