Tetracosanuclear nickel complexes as effective catalysts for cycloaddition of carbon dioxide with epoxides.

A series of well-defined tetracosanuclear nickel complexes 3-7 facilely produced by one-pot synthesis were active catalysts for cycloaddition of CO2 and cyclohexene oxide (CHO). These nickel complexes were doughnut-like supramolecular coordination complexes involving eight repeating units, and each of them contains one Schiff base ligand and three nickel(II) ions. Notably, the 24-nuclear nickel cluster complex 3 in combination with nucleophilic additives was the most efficient catalyst to mediate CO2 coupling with CHO to generate CO2-based cis-cyclohexene carbonates. In addition to CO2/CHO cycloaddition, complex 3 was also found to effectively couple CO2 with other alicyclic epoxides, generating the corresponding cyclic carbonates. Additionally, kinetic investigations for CO2 cycloaddition of CHO using 3 were reported.

Bimetallic nickel complexes containing imidazole-based phenolate ligands as efficient catalysts for the copolymerization of carbon dioxide with epoxides.

The utilization of hexadentate imidazole-derived diamine-bisphenolate ligands to construct structurally well-defined bimetallic nickel catalysts that enable the mediation of the copolymerization of carbon dioxide with alicyclic epoxides was reported for the first time. A series of dinickel carboxylate/nitrophenolate complexes were facilely prepared through a one-pot procedure and their structures were fully determined by single crystal X-ray structural analysis. Dinickel complexes 1-10 were used as single-component catalysts, and were evaluated for the copolymerization of CO2 and cyclohexene oxide (CHO), for which acetato-incorporated complex 1 was proved to exhibit the best activity. Not only has the controllability of binickel catalyst 1 for CO2/CHO copolymerization been demonstrated, but also an "immortal" character for the same polymerization has been realized. Furthermore, detailed kinetic studies of polymerization catalysis of this type were undertaken, and the kinetics results revealed a first-order dependence on both Ni complex 1 and CHO concentrations. This is a successful example of the introduction of the easily accessible nitrogen-heterocycle group, the imidazole moiety, into phenolate ligands for the development of high-performance homogeneous catalysts towards the bimetallic complex-catalyzed copolymerization of CO2 and epoxides.

Creation of Chitosan-Based Nanocapsule-in-Nanofiber Structures for Hydrophobic/Hydrophilic Drug Co-Delivery and Their Dressing Applications in Diabetic Wounds.

Nanofiber meshes (NFMs) loaded with therapeutic agents are very often employed to treat hard-to-heal wounds such as diabetic wounds. However, most of the NFMs have limited capability to load multiple or hydrophilicity distinctive-therapeutic agents. The therapy strategy is therefore significantly hampered. To tackle the innate drawback associated with the drug loading versatility, a chitosan-based nanocapsule-in-nanofiber (NC-in-NF) structural NFM system is developed for simultaneous loading of hydrophobic and hydrophilic drugs. Oleic acid-modified chitosan is first converted into NCs by the developed mini-emulsion interfacial cross-linking procedure, followed by loading a hydrophobic anti-inflammatory agent Curcumin (Cur) into the NCs. Sequentially, the Cur-loaded NCs are successfully introduced into reductant-responsive maleoyl functional chitosan/polyvinyl alcohol NFMs containing a hydrophilic antibiotic Tetracycline hydrochloride. Having a co-loading capability for hydrophilicity distinctive agents, biocompatibility, and a controlled release property, the resulting NFMs have demonstrated the efficacy on promoting wound healing either in normal or diabetic rats.

Bimetallic Nickel Complexes as Effective and Versatile Catalysts for Copolymerization of Epoxides with Carbon Dioxide or Phthalic Anhydride: Catalysis and Kinetics.

This study reported three novel structurally well-characterized dihalide dinuclear nickel complexes containing benzotriazole-based 1,3-diamine-linked bisphenolate ligands, which were high-performance catalysts for ring-opening copolymerization (ROCOP) of cyclohexene oxide (CHO) and carbon dioxide (CO2). The dinickel diiodo 3 was shown to catalyze CO2 copolymerization of CHO with high activity (turnover frequency up to 2250 h-1), excellent selectivity (>99% polycarbonates, >99% carbonate repeated units), and good molecular weight controllability. Apart from CO2/CHO copolymerization, the most active complex 3 was found to effectively catalyze ROCOP of CHO with phthalic anhydride (PA). Not only has the controllable manner of 3 for PA/CHO copolymerization been proven but also a broad substrate scope for PA copolymerization of epoxides by the same complex has been achieved. Diverse terminal or internal epoxides were demonstrated to copolymerize PA by 3, producing the corresponding semiaromatic polyesters with good activity and excellent product selectivity. Kinetic studies for CHO copolymerization of CO2 or PA mediated by 3 were systematically investigated. For kinetics of PA/CHO copolymerization, it allowed us to propose the rate equation of -d[CHO]/dt = kp[3]1[PA]0[CHO]1, and such catalysis displayed a first-order dependence on both dinickel complex and CHO concentrations as well as a zero order for PA. This work offers a bimetallic dihalide nickel complex as an efficient and versatile catalyst for two different types of copolymerization catalysis.

Biodegradable Carbon Dioxide-Derived Non-Viral Gene Vectors for Osteosarcoma Gene Therapy.

Osteosarcoma often occurs in children and adolescents with high invasiveness and high mortality. Polo-like kinase 1 (PLK1) overexpressed in most tumors promotes cancer cell proliferation and transformation. PLK1 is considered as a therapeutic target for osteosarcoma. RNA interference-based therapies are employed to combat osteosarcoma through silencing PLK1 gene expression. However, the treatment results remain unsatisfactory due to the lack of a safe and efficient nonviral gene vector. To tackle this hurdle, biodegradable and CO2 -derivative cationic poly(vinylcyclohexene carbonates) (CPCHCs) are used as gene vectors to perform a siPLK1 therapeutic strategy for osteosarcoma treatment. Of those CPCHCs, CPCHC60 demonstrates the most excellent performance in gene transfection efficiency, endo-lysosome escaping, biodegradability, and biosafety. With the treatment of CPCHCs/siRNA nanoparticles, the expression level of PLK1 gene in osteosarcoma cells is significantly down-regulated. Subsequently, cells are arrested in the G2 /M phase and subsequently dead in the form of apoptosis, resulting in significant tumor regression both in vitro and in vivo. This study brings a new insight into the development of superior nonviral gene vectors for practical cancer treatment. Based on the results, the resulting nanoparticle-based gene drug formation is considered to have a highly successful chance in further translational nanomedicine applications.

Dinuclear Nickel Complexes Using Hexadentate Benzothiazole-Based Diamine-Bisphenolate Ligands: Highly Active Catalysts for Copolymerization of Carbon Dioxide with Epoxides.

We reported for the first time the utilization of hexadentate benzothiazole-based diamine-bisphenolate ligands to synthesize structurally well-characterized dinickel dicarboxylate complexes and studied their catalysis for copolymerization of carbon dioxide with epoxides. Dinickel carboxylate complexes having a 1,3-diamine-bridged backbone were demonstrated to be high-performance catalysts for alternating copolymerization of CO2 and cyclohexene oxide (CHO) with high product selectivity. Particularly, acetate-supported nickel complex 2 enabled us to promote such CO2-copolymerization of this kind with a maximum turnover frequency of up to 2600 h-1 and gave good molecular weight controllability under high-pressure conditions. It is worth noting that bimetallic Ni catalyst 2 was also capable of mediating the catalytic CO2-polymerization of alicyclic epoxides at atmospheric pressure. Kinetic investigations of CO2/CHO copolymerization by 2 allowed us to determine the rate equation of -d[CHO]/dt = kp[2]1[CHO]1, and such catalysis exhibited a first-order dependence on both dinickel complex and CHO concentrations.

Preparation of CO2 -Based Cationic Polycarbonate/Polyacrylonitrile Nanofibers with an Optimal Fibrous Microstructure for Antibacterial Applications.

Utilizing CO2 as one of the monomer resources, poly(vinylcyclohexene carbonates) (PVCHCs) are used as the precursor for preparing cationic PVCHCs (CPVCHCs) via thiol-ene click functionalization. Through the functionalization, CPVCHC-43 with a tertiary amine density of 43% relative to the backbone is able to display a significantly antibacterial ability against Staphylococcus aureus (S. aureus). Blending CPVCHC-43 with polyacrylonitrile (PAN), CPVCHC/PAN nanofiber meshes (NFMs) have been successfully prepared by electrospinning. More importantly, two crucial fibrous structural factors including CPVCHC/PAN weight ratio and fiber diameter have been systematically investigated for the effects on the antibacterial performance of the NFMs. Sequentially, a quaternization treatment has been employed on the NFMs with an optimal fibrous structure to enhance the antibacterial ability. The resulting quaternized NFMs have demonstrated the great biocidal effects against Gram-positive and Gram-negative bacteria. Moreover, the excellent biocompatibility of the quaternized NFMs have also been thoroughly evaluated and verified.

Recent advances and applications to cultural heritage using ATR-FTIR spectroscopy and ATR-FTIR spectroscopic imaging.

Scientific investigation of cultural heritage objects plays a vital role in a responsible modern approach to conservation and archaeology. Recent advances in spectroscopy, such as the development of Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy and ATR-FTIR spectroscopic imaging, have opened up a window of opportunities for characterisation of materials in artefacts and collections from museums. This review summarises some of the recent advances and applications of these ATR-FTIR spectroscopic analytical techniques in the area of cultural heritage studies, including examples of cross-sections of oil paintings, paper, textiles, plastic objects, potteries, glasses and mineral artefacts. Two of the major advantages of ATR mode measurements are minimal or no requirements for sample preparation and its provision for high lateral spatial resolution. In addition to conventional single point detection, two-dimensional mapping and imaging is especially beneficial for chemical visualisation of multi-layered structure cultural objects. This review also explores the implications of these advantages as well as some limitations and provides a brief outlook for the possible future developments in this area.

Carbon Dioxide-Derived Biodegradable and Cationic Polycarbonates as a New siRNA Carrier for Gene Therapy in Pancreatic Cancer.

Pancreatic cancer is an aggressive malignancy associated with poor prognosis and a high tendency in developing infiltration and metastasis. K-ras mutation is a major genetic disorder in pancreatic cancer patient. RNAi-based therapies can be employed for combating pancreatic cancer by silencing K-ras gene expression. However, the clinical application of RNAi technology is appreciably limited by the lack of a proper siRNA delivery system. To tackle this hurdle, cationic poly (cyclohexene carbonate) s (CPCHCs) using widely sourced CO2 as the monomer are subtly synthesized via ring-opening copolymerization (ROCOP) and thiol-ene functionalization. The developed CPCHCs could effectively encapsulate therapeutic siRNA to form CPCHC/siRNA nanoplexes (NPs). Serving as a siRNA carrier, CPCHC possesses biodegradability, negligible cytotoxicity, and high transfection efficiency. In vitro study shows that CPCHCs are capable of effectively protecting siRNA from being degraded by RNase and promoting a sustained endosomal escape of siRNA. After treatment with CPCHC/siRNA NPs, the K-ras gene expression in both pancreatic cancer cell line (PANC-1 and MiaPaCa-2) are significantly down-regulated. Subsequently, the cell growth and migration are considerably inhibited, and the treated cells are induced into cell apoptotic program. These results demonstrate the promising potential of CPCHC-mediated siRNA therapies in pancreatic cancer treatment.

Reversible Underwater Adhesion: The Unique C-shaped Suckers of Net-winged Midge Larvae (Blepharicera sp.).

Aquatic insects living in fast-flowing streams have developed various types of attachment systems to resist being carried away by strong currents. Combinations of various attachment devices offer aquatic insects advantages in underwater adhesion on substrates with different surface properties. In this study, the net-winged midge (Blepharicera sp.) larvae were investigated to understand micro-/nano-structural attachment mechanisms. The hierarchical structure of insect adhesive surfaces was characterized using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Centrifugal measurements were also conducted to measure the critical rotational velocity at which the larvae of Blepharicera sp. can adhere to substrates with varying roughness. Commercial suckers require smooth substrate surface to maintain a pressure that is lower than the surrounding pressure for adhesion under the sucker cup while the suckers of net-winged midge larvae possess hierarchical micro-/nano-structures, which attach closely to rough surfaces underwater. Furthermore, the functions of microstructures observed on the sucker, including wrinkled surface, inward setae, outer fibers, and nick were explored and may contribute to underwater adhesion. The aligned C-shaped suckers can attach and detach effectively by closing or opening the gap. The unique microstructure and adhesion capability of such suckers could shed light on the design and synthesis of novel bio-inspired devices for reversible underwater adhesion.

Guide sheath-assisted ureteroscope lithotripsy for upper ureteral calculi: An observational study on 81 cases.

The present study assessed the clinical efficacy of guide sheath-assisted ureteroscope lithotripsy in the treatment of upper ureteral calculi. A total of 81 patients with upper ureteral calculi underwent ureteroscope lithotripsy assisted by a guide sheath between January 2012 and June 2014; of these, 63 patients were successfully treated with simple rigid ureteroscope lithotripsy assisted by a ureteral access sheath, and 18 patients were successfully treated with rigid and flexible ureteroscope lithotripsy assisted by a guide sheath. At 1 day after the surgery, ultrasound examination of kidneys, ureters and bladder, and urinary system computed tomography were used to re-check for residual stones, and 69 patients had stones with a diameter of <2 mm in the renal pelvis, while 12 had stones of 2-4 mm in diameter. The operation time was 30-115 min (average, 56.0±4.8 min); all patients underwent a successful surgical procedure. A total of 7 patients had an elevated temperature 37.4-39.1°C (mean temperature, 37.7±0.3°C) after the surgery, but no other major complications were noted. After 1 month, the residual stones were completely discharged, so that the stone clearance rate was 100%. All patients were followed up for 3-12 months and no associated complications occurred. Overall, ureteroscope lithotripsy assisted by a guide sheath for the treatment of upper ureteral calculi had the benefit of water injection and reflux functions, as well as enhanced vision, reduced pressure within the renal pelvis, good discharge of stones as well as an improved efficiency and success rate compared with simple ureteroscopic lithotripsy.

[Penoplasty with T-shaped incision and three-point fixation for concealed penis].

OBJECTIVE: To search for a safe and effective method of penoplasty with low incidence of complications for concealed penis by evaluating penoplasty with T-shaped incision and three-point fixation in comparison with modified Devine's technique. METHODS: We retrospectively analyzed 169 cases of concealed penis treated in our center by penoplasty with T-shaped incision and three-point fixation (group A, n = 110) or modified Devine's surgery (group B, n = 59). We compared the operation time, postoperative complications, and recurrence rate between the two groups of patients. RESULTS: Operations were successfully completed in all the cases, the urinary catheters removed at 3 days and the elastic bandages applied for 2 to 4 weeks. The patients were followed up for 4 to 12 months. The penis was satisfactorily exposed. The operative time was significantly shorter in group A than in B (ï¼»52.8 ± 6.9ï¼½ vs ï¼»61.5 ± 10.6ï¼½ min, P < 0.001), the postoperative complication rate was obviously lower in the former than in the latter (prepuce edema: 17.27% ï¼»19/110ï¼½ vs 33.89% ï¼»20/59ï¼½, P = 0.021; bleeding: 0.90% ï¼»1/110ï¼½ vs 3.38% ï¼»2/59ï¼½, P = 0.552; skin necrosis: 0.90% ï¼»1/110ï¼½ vs 5.08% ï¼»3/59ï¼½, P = 0.123; skin infection: 0.90% ï¼»1/110ï¼½ vs 5.08% ï¼»3/59ï¼½, P = 0.123), and so was the recurrence rate (0.90% ï¼»1/110ï¼½ vs 6.77% ï¼»4/59ï¼½, P = 0.032). CONCLUSIONS: Penoplasty with T-shaped incision and three-point fixation deserves to be popularized clinically for its advantages of minor invasion, clear exposure, reliable penile fixation, low incidence of postoperative complications and recurrence, and satisfactory outcomes.

[Etiological factors for calculus-associated seminal vesiculitis: Analysis of calculus composition in 6 cases].

OBJECTIVE: To explore the etiological factors for calculus-associated seminal vesiculitis by analyzing the composition of seminal vesicle calculus samples. METHODS: This retrospective study included 6 cases of recurrent hematospermia diagnosed with seminal vesicle calculus by non-contrast pelvic CT. The patients were aged 28 to 69 years, with persistent or recurrent hematospermia for 3 months to 6 years, and 5 of them with a history of acute urethritis. All the patients underwent seminal vesiculoscopy, which confirmed calculus-associated seminal vesiculitis. The calculus samples were obtained with a spiral dislodge and their composition was determined with a second-generation infrared calculus composition analyzer. The patients were followed up for 2 to 12 weeks postoperatively, during which non-contrast pelvic CT was employed for observation of recurrent calculus in the reproductive tract. RESULTS: Pelvic CT scanning indicated recurrence of seminal vesicle calculus in 3 cases at 12 weeks postoperatively, of which, 2 were accompanied with recurrent hematospermia, both observed at 4 weeks after operation. As for the composition of the calculus, the infrared calculus composition analyzer revealed struvite (magnesium ammonium phosphate hexahydrate) in 5 cases and a mixture of calcium oxalate dihydrate, calcium oxalate monohydrate, and carbonate apatite in the other one. CONCLUSIONS: Seminal vesicle calculi are most commonly composed of struvite, and infection is the main etiological factor for calculus-associated seminal vesiculitis.

Climbing upstream: Multi-scale structural characterization and underwater adhesion of the Pulin river loach (Sinogastromyzon puliensis).

Hillstream fishes live in the current with high flow velocity and strong water impact. To survive in such environments, they evolved various adhesive apparatus and attachment mechanisms. In this study, we investigated the Pulin river loach (Sinogatromyzon puliensis) known for its ability to climb vertically against rapid torrent. The whole body forms a suction system, consisting of lips, overlapped pectoral and fused pelvic fins. The hierarchical structure of lips and fins was characterized by Scanning Electron Microscopy. Polygonal pad-like protrusions, called unculi, were found on the lips and micro-sized, needle-like unculi (setae) covered both pectoral and pelvic fin rays. Pull-off stress was measured to evaluate the adhesion capability of dead river loach to substrates with varying surface roughness and compared with commercial suction cups. Results showed that river loaches can adhere equally well to surfaces with varying roughness while suction cups fail to adhere to rough surfaces. Underwater adhesion was accomplished by three possible mechanisms: (1) unculi enhance friction force on substrates, (2) setae interlock with irregularities, and (3) setae seal the edge and prevent leakage. The specialized adhesion apparatus and capability of Pulin river loach could provide inspirations and design strategies for novel underwater adhesives and devices.

[Application value of Toshiba 320-row dynamic volumetric CT angiography in the diagnosis of venous erectile dysfunction].

Objective: To investigate the application value of Toshiba 320-row dynamic volumetric CT angiography in the diagnosis of venous erectile dysfunction (VED). METHODS: We enrolled in this study 33 patients diagnosed with ED by audiovisual sexual stimulation screening in the outpatient department. Penile erection was induced in the patients by injection of 2 mg phentolamine plus 30 mg papaverine into the corpus cavernosum, followed by that of contrast agent of iobitridol through the vein and corpus cavernosum successively. Then 320-row dynamic volumetric CT angiography was performed and the images of the corpus cavernosum in the arterial and venous phases were collected and processed. RESULTS: Different degrees of abnormal venous drainage were observed in 29 of the patients, including 7 cases (24.1%) of back deep venous leakage, 6 cases (20.7%) of foot venous leakage, 3 cases (10.3%) of dorsal superficial venous leakage, 1 case (3.5%) of intervertebral venous leakage, 2 cases (6.9%) of cavernous venous leakage, and 10 cases (34.5%) of mixed venous leakage. Ten of the patients underwent surgery, dorsal deep penile vein ligation in 2 cases, dorsal deep vein embedding plus foot vein ligation in 4, and foot vein ligation in the other 4. Eight of the patients were followed up for 3－12 months post-operatively, during which 2 achieved obvious erectile improvement, while the other 6 gained normal penile erection. CONCLUSIONS: Toshiba 320-row dynamic volumetric CT angiography is a reliable method for the diagnosis of VED, which displays the precise location of venous leakage for clinical treatment, with the advantages of clearer images, lower doses of contrast agent and radiation, and faster examination than X-ray penile angiography.

[Construction of oxalate-degrading intestinal stem cell population in mice].

OBJECTIVE: The oxalate-degradation genes of Oxalobacter formigenes (Ox.F)-frc gene and oxc gene-were cloned and transfected into intestinal stem cell population of the mouse to make the latter obtain oxalate-degradation function. METHODS: (1) The dicistronic eukaryotic expression vector, which could express oxc gene and frc gene in the same time, pIRES-oxc-frc was constructed. (2) The intestinal stem cell population of the mouse were isolated and cultured, and the function of the cell growth and differentiation was identified. (3) The cells were transfected with pIRES-oxc-frc. After selection by G418, the function of the cell growth and differentiation and the the expression of the objective genes were identified. (4) The concentration of the oxalate in the culture medium which was used to culture the transgenic cells was determined by ion chromatography to explore the oxalate-degradation function of the cells. RESULTS: Ox.F could be isolated and cultured from the feces of Chinese people. Compared with the foreign reports, a certain morphologic variation of the Ox.F existed. But the oxc gene and frc gene showed high homology with the sequence reported in GenBank. The recombinant plasmid containing oxc gene and frc gene could successfully be transfected into the intestinal stem cell population of the mouse. The expression of the objective genes was normal. The concentration of the oxalate in the culture fluid of the transgenic intestinal stem cell population [(2.48 +/- 0.03 g/L)] was lower than those of the normal group [(2.69 +/- 0.01) g/L] and the control group [(2.69 +/- 0.01) g/L, P < 0.01]. CONCLUSION: The oxc gene and the frc gene could be transfected into the intestinal stem cell population of the mouse, and the cells could be given oxalate-degrading function. The gene of prokaryocyte could be introduced into the eukaryocyte for a successful expression.

Stable expression of the oxc and frc genes from Oxalobacter formigenes in human embryo kidney 293 cells: implications for gene therapy of hyperoxaluria.

Hyperoxaluria can lead to multiple pathologic conditions such as recurrent urolithiasis, oxalosis, nephrocalcinosis and even renal failure, but there is no known oxalate-degrading pathway in the human body, and current therapeutic options for patients with hyperoxaluria are limited. Oxalyl-CoA decarboxylase and formyl-CoA transferase are the key enzymes in the oxalate catabolism of Oxalobacter formigenes which dwell in the intestine of vertebrates and have an important symbiotic relationship with their hosts. The aim of this study was to insert the oxalate-degrading enzyme genes into human embryo kidney (HEK) 293 cells and to evaluate if the oxalate-degrading enzymes could be expressed in these cells and keep their enzyme activity. We present here the cloning of the two genes from O. formigenes and their subsequent expression in HEK293 cells. The results showed that the expression of oxalyl-CoA decarboxylase and formyl-CoA transferase was confirmed by RT-PCR and Western blotting, and the proteins were located in the cytoplasm of transfected cells. Furthermore, the transfected cells were capable to a certain degree of degrading oxalate. These findings suggest that the transfer of oxalate-degrading enzyme genes into human cells is possibly a potential candidate for the gene therapy of hyperoxaluria.