CO2 Fixation and PCHC Depolymerization by a Dinuclear ß-Diketiminato Zinc Complex.

The production of cyclic carbonates and (or) polycarbonates from the coupling of carbon dioxide (CO2 ) with epoxides is a practical strategy for CO2 fixation. Chemically recycling of the polycarbonates is also urgently needed for sustainable development of plastics. Here a dinuclear ß-diketiminato (BDI) methyl zinc complex((BDI-ZnMe)2 , 1) is reported to achieve not only selective cyclic carbonates from cycloaddition of CO2 to meso-CHO in the presence of cocatalyst, but also effective depolymerization of PCHC into trans-CHC. The trans-CHC can be further transformed into cis-CHC, thus demonstrating great application potentials of this strategy in CO2 fixation and chemical recycling of plastics.

Ultrasound-Responsive Peptide Nanogels to Balance Conflicting Requirements for Deep Tumor Penetration and Prolonged Blood Circulation.

A series of biological barriers need to be overcome for therapeutic nanocarriers accumulating at the tumor site and uptaken by cancer cells. One strategy is to construct switchable nanocarriers to meet the conflicting requirements for various physiology environments. In this work, besides widely studied endogenous stimuli-responsiveness, an exogenous ultrasound responsiveness was additionally embedded into nanocarriers to balance the conflicting needs of prolonged blood circulation and deep tumor penetration. Polylysine and Pluronic F127 were first coassembled and then cross-linked by genipin to form stable nanogel structure. Subsequently, ICAM-1 antibody was grafted onto the nanogel (designated as GenPLPFT) for active tumor targeting. Upon external sonication, the F127 was shed from GenPLPFT to induce swelling of nanogel with reduced stability and accelerated drug release. In detail, sonication leads to GenPLPF swelling from 329 to 516 nm, while its Young's modulus significantly decreased from 336.78 to 3.93 kPa. Through intravenous injection, relatively rigid GenPLPFT was able to achieve a high level of accumulation at tumor site by active targeting and long-term blood circulation. Moreover, under sonication at the tumor site, GenPLPFT became softer with enhanced deformability to achieve deep tumor penetration. In addition, in vivo studies revealed that GenPLPFT was able to penetrate into the deep area of xenografted tumor with enhanced antitumor efficacy and reduced toxicity. Overall, this peptide nanogel with ultrasound-responsive stiffness demonstrates an effective approach to overcome a series of biological barriers for enhanced deep tumor therapy.

Ångstrom-scale silver particle-embedded carbomer gel promotes wound healing by inhibiting bacterial colonization and inflammation.

Poor wound healing after diabetes or extensive burn remains a challenging problem. Recently, we presented a physical approach to fabricate ultrasmall silver particles from Ångstrom scale to nanoscale and determined the antitumor efficacy of Ångstrom-scale silver particles (AgÅPs) in the smallest size range. Here we used the medium-sized AgÅPs (65.9 ± 31.6 Å) to prepare carbomer gel incorporated with these larger AgÅPs (L-AgÅPs-gel) and demonstrated the potent broad-spectrum antibacterial activity of L-AgÅPs-gel without obvious toxicity on wound healing-related cells. Induction of reactive oxygen species contributed to L-AgÅPs-gel-induced bacterial death. Topical application of L-AgÅPs-gel to mouse skin triggered much stronger effects than the commercial silver nanoparticles (AgNPs)-gel to prevent bacterial colonization, reduce inflammation, and accelerate diabetic and burn wound healing. L-AgÅPs were distributed locally in skin without inducing systemic toxicities. This study suggests that L-AgÅPs-gel represents an effective and safe antibacterial and anti-inflammatory material for wound therapy.

The comparison between force volume and peakforce quantitative nanomechanical mode of atomic force microscope in detecting cell's mechanical properties.

Atomic force microscope (AFM) has been widely used in the biological field owing to its high sensitivity (subnanonewton), high spatial resolution (nanometer), and adaptability to physiological environments. Nowadays, force volume (FV) and peakforce quantitative nanomechanical (QNM) are two distinct modes of AFM used in biomechanical research. However, numerous studies have revealed an extremely confusing phenomenon that FV mode has a significant difference with QNM in determining the mechanical properties of the same samples. In this article, for the case of human benign prostatic hyperplasia cells (BPH) and two cancerous prostate cells with different grades of malignancy (PC3 and DU145), the differences were compared between FV and QNM modes in detecting mechanical properties. The results show measured Young's modulus of the same cells in FV mode was much lower than that obtained by QNM mode. Combining experimental results with working principles of two modes, it is indicated that surface adhesion is highly suspected to be a critical factor resulting in the measurement difference between two modes. To further confirm this conjecture, various weight ratios of polydimethylsiloxane (PDMS) were assessed by two modes, respectively. The results show that the difference of Young's modulus measured by two modes increases with the surface adhesion of PDMS, confirming that adhesion is one of the significant elements that lead to the measurement difference between FV and QNM modes.

Preparation of Molecularly Imprinted Composites Initiated by Hemin/Graphene Hybrid Nanosheets and Its Application in Detection of Sulfamethoxazole.

Molecularly imprinted polymers (MIPs) exhibit high selectivity resulting from imprinted cavities and superior performance from functional materials, which have attracted much attention in many fields. However, the combination of MIPs film and functional materials is a great challenge. In this study, hemin/graphene hybrid nanosheets (H-GNs) were used to initiate the imprinted polymerization by catalyzing the generation of free radicals. Thus, MIPs using sulfamethoxazole as the template was directly prepared on the surface of H-GNs without any film modification. Most importantly, the template could be absorbed on the H-GNs to enhance the number of imprinted sites per unit surface area, which could improve the selectivity of MIPs film. Thus, the composites could exhibit high adsorption capacity (29.4 mg/g), imprinting factor (4.2) and excellent conductivity, which were modified on the surface of electrode for rapid, selective and sensitive detection of sulfamethoxazole in food and serum samples. The linear range was changed from 5 µg/kg to 1 mg/g and the limit of detection was 1.2 µg/kg. This sensor was free from interference caused by analogues of sulfamethoxazole, which provides a novel insight for the preparation of MIPs-based sensor and its application in food safety monitoring and human exposure study.

In vitro mimicking the morphology of hepatic lobule tissue based on Ca-alginate cell sheets.

Artificial cell sheets are commonly utilized as buiding blocks for tissue engineering. We propose a novel approach in the fabrication of Ca-alginate gel sheets, embedded with liver cells (RLC-18) in order to mimic liver lobule tissue. Ca-alginate sheets with hepatic lobule-shaped patterns were deposited onto a micro-electrode device using electrodeposition. Viability of embedded cells was ensured to exceed 80%. Cell morphology and biofunctionality were monitored during the one-week culture period and results compared with those of traditional 2D culture. In addition, we detached cell sheets from the electrode substrate and stacked them into a 3D multi-layered structure to mimic the morphology of liver lobule tissue.

Low-grade myofibroblastic sarcoma of gastric cardia on 18F-FDG positron emission tomography/computed tomography: An extremely rare case report.

RATIONALE: Low-grade myofibroblastic sarcoma (LGMS) is a rare mesenchyme-derived tumor, which usually occurs in head, neck (especially tongue and mouth), and limbs. In this report, we described a case of gastric LGMS by F-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT), which has not been reported previously. PATIENT CONCERNS: A 51-year-old female patient was admitted to our hospital with upper abdominal discomfort for 1 year and gradually increased eating difficulties over the last 3 months. From gastroscopy, an ulcer of 1.0 cm × 1.2 cm at the entrance of cardia and stiffness of peripheral mucosa were found, leading to suspicion of cardia cancer. F-FDG PET/CT was performed for further diagnosis and staging. DIAGNOSES: According to pathological findings in combination with immunohistochemical features, diagnosis of gastric LGMS was made. INTERVENTIONS: To relieve symptoms of upper gastrointestinal obstruction in the patient, proximal gastrectomy was carried out 1 week after the F-FDG PET/CT scan. OUTCOMES: The patient died due to advanced tumor. LESSONS: F-FDG PET/CT scan showed local thickening of the gastric wall, invasion of adjacent soft tissue, diaphragmatic and peritoneal metastasis at early stage, absence of regional lymph node metastasis, and increased F-FDG metabolism in primary tumor and metastatic tumor.

Fabrication and evaluation of tumor-targeted positive MRI contrast agent based on ultrasmall MnO nanoparticles.

Gd(III) chelate is currently used as positive magnetic resonance imaging (MRI) contrast agent in clinical diagnosis, but generally induces the risk of nephrogenic systemic fibrosis (NSF) due to the dissociated Gd(3+) from Gd(III) chelates. To develop a novel positive MRI contrast agent with low toxicity and high sensitivity, ultrasmall MnO nanoparticles were PEGylated via catechol-Mn chelation and conjugated with cRGD as active targeting function to tumor. Particularly, the MnO nanoparticles with a size of ca. 5nm were modified by α,ß-poly(aspartic acid)-based graft polymer containing PEG and DOPA moieties and, meanwhile, conjugated with cRGD to produce the contrast agent with a size of ca. 100nm and a longitudinal relaxivity (r1) of 10.2mM(-1)S(-1). Such nanoscaled contrast agent integrated passive- and active-targeting function to tumor, and its efficient accumulation behavior in tumor was verified by in vivo distribution study. At the same time, the PEG moiety played a role of hydrophilic coating to improve the biocompatibility and stability under storing and physiological conditions, and especially might guarantee enough circulation time in blood. Moreover, in vivo MRI revealed a good and long-term effect of enhancing MRI signal for as-fabricated contrast agent while cell viability assay proved its acceptable cytotoxicity for MRI application. On the whole, the as-fabricated PEGylated and cRGD-functionalized contrast agent based on ultrasmall MnO nanoparticles showed a great potential to the T1-weighted MRI diagnosis of tumor.

Preliminary enrichment and separation of chlorogenic acid from Helianthus tuberosus L. leaves extract by macroporous resins.

In the present study, a simple and efficient method for the preparative separation of 3-CQA from the extract of Helianthus tuberosus leaves with macroporous resins was studied. ADS-21 showed much higher adsorption capacity and better adsorption/desorption properties for 3-CQA among the tested resins. The adsorption of 3-CQA on ADS-21 resin at 25°C was fitted best to the Langmuir isotherm model and pseudo-second-order kinetic model. Dynamic adsorption/desorption experiments were carried out in a glass column packed with ADS-21 to optimise the separation process of 3-CQA from H. tuberosus leaves extract. After one treatment with ADS-21, the content of 3-CQA in the product was increased 5.42-fold, from 12.0% to 65.2%, with a recovery yield of 89.4%. The results demonstrated that the method was suitable for large-scale separation and manufacture of 3-CQA from H. tuberosus leaves.

On-chip self-assembly of cell embedded microstructures to vascular-like microtubes.

Currently, research on the construction of vascular-like tubular structures is a hot area of tissue engineering, since it has potential applications in the building of artificial blood vessels. In this paper, we report a fluidic self-assembly method using cell embedded microstructures to construct vascular-like microtubes. A novel 4-layer microfluidic device was fabricated using polydimethylsiloxane (PDMS), which contains fabrication, self-assembly and extraction areas inside one channel. Cell embedded microstructures were directly fabricated using poly(ethylene glycol) diacrylate (PEGDA) in the fabrication area, namely on-chip fabrication. Self-assembly of the fabricated microstructures was performed in the assembly area which has a micro well. Assembled tubular structures (microtubes) were extracted outside the channel into culture dishes using a normally closed (NC) micro valve in the extraction area. The self-assembly mechanism was experimentally demonstrated. The performance of the NC micro valve and embedded cell concentration were both evaluated. Fibroblast (NIH/3T3) embedded vascular-like microtubes were constructed inside this reusable microfluidic device.

[A case report of giant cemento-ossifying fibroma].

Cemento-ossifying fibroma is a rare benign tumor from periodontium, which usually occurs in mandible body and mandible ramus. It consists of collagen fibrils, fibroblast, and cementoblast. This article reported a case of giant cemento-ossifying fibroma and discussed the clinical features and treatment.