Adhesive cryogel particles for bridging confined and irregular tissue defects.

BACKGROUND: Reconstruction of damaged tissues requires both surface hemostasis and tissue bridging. Tissues with damage resulting from physical trauma or surgical treatments may have arbitrary surface topographies, making tissue bridging challenging. METHODS: This study proposes a tissue adhesive in the form of adhesive cryogel particles (ACPs) made from chitosan, acrylic acid, 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The adhesion performance was examined by the 180-degree peel test to a collection of tissues including porcine heart, intestine, liver, muscle, and stomach. Cytotoxicity of ACPs was evaluated by cell proliferation of human normal liver cells (LO2) and human intestinal epithelial cells (Caco-2). The degree of inflammation and biodegradability were examined in dorsal subcutaneous rat models. The ability of ACPs to bridge irregular tissue defects was assessed using porcine heart, liver, and kidney as the ex vivo models. Furthermore, a model of repairing liver rupture in rats and an intestinal anastomosis in rabbits were established to verify the effectiveness, biocompatibility, and applicability in clinical surgery. RESULTS: ACPs are applicable to confined and irregular tissue defects, such as deep herringbone grooves in the parenchyma organs and annular sections in the cavernous organs. ACPs formed tough adhesion between tissues [(670.9 ± 50.1) J/m2 for the heart, (607.6 ± 30.0) J/m2 for the intestine, (473.7 ± 37.0) J/m2 for the liver, (186.1 ± 13.3) J/m2 for muscle, and (579.3 ± 32.3) J/m2 for the stomach]. ACPs showed considerable cytocompatibility in vitro study, with a high level of cell viability for 3 d [(98.8 ± 1.2) % for LO2 and (98.3 ± 1.6) % for Caco-2]. It has comparable inflammation repair in a ruptured rat liver (P = 0.58 compared with suture closure), the same with intestinal anastomosis in rabbits (P = 0.40 compared with suture anastomosis). Additionally, ACPs-based intestinal anastomosis (less than 30 s) was remarkably faster than the conventional suturing process (more than 10 min). When ACPs degrade after surgery, the tissues heal across the adhesion interface. CONCLUSIONS: ACPs are promising as the adhesive for clinical operations and battlefield rescue, with the capability to bridge irregular tissue defects rapidly.

[Effects of simulated precipitation changes on plant community characteristics of wetland in the Yellow River Delta, China]. / 模拟降雨量变化对黄河三角洲湿地植物群落特征的影响.

Under the changing climate scenario, changes in precipitation regimes are expected to alter soil water and salinity conditions, with consequences on the characteristics of plant community in estuarine wetland. Here, we used a six-year (2015-2020) precipitation manipulation experiment to examine how plant community characteristics responded to precipitation changes in the Yellow River Delta. The results showed that soil electrical conductivity significantly decreased, while soil moisture significantly increased with increasing precipitation. Precipitation changes altered plant community composition. Increased precipitation reduced the absolute dominance of Suaeda glauca and Suaeda salsa, but increased that of Triarrhena sacchariflora and Imperata cylindrica. Shannon index and Margalef richness index of plant community significantly increased with increasing precipitation. Compared with the control, both decreased and increased precipitation decreased the plant community abundance, frequency and coverage. The treatment of 60% increased precipitation significantly decreased plant community frequency by 54.9%, while the 60% decreased precipitation, 40% decreased precipitation, 40% increased precipitation and 60% increased precipitation treatment significantly decreased plant abundance by 38.9%, 33.8%, 35.8% and 45.7%, respectively. The aboveground biomass significantly increased with increasing precipitation, but aboveground plant biomass under 60% increased precipitation treatment being lower than that reducing under 40% increased precipitation treatment, probably due to the negative effects of flooding stress. In addition, Margalef richness index had a significantly positive relationship with aboveground biomass. Aboveground biomass, Shannon diversity index, Margalef richness index, and Simpson diversity index were negatively related to soil electrical conductivity, and aboveground plant biomass was positively related to soil moisture. Our results revealed that precipitation changes regulate growth characteristics, species composition, and diversity of plant community by altering soil water and salinity conditions in a coastal wetland.

Time-resolved fluorescence and chemometrics-assisted excitation-emission fluorescence for qualitative and quantitative analysis of scopoletin and scopolin in Erycibe obtusifolia Benth.

This paper presents a new strategy for qualitative identification of scopoletin and scopolin in Erycibe obtusifolia Benth using time-resolved (lifetimes) fluorescence and quantitative analysis with chemometrics-assisted excitation-emission matrix (EEM) fluorescence. Due to the significant spectral overlapping among analytes and interference, the use of the more selective time-resolved fluorescence is proposed for qualitative identification in quality control of traditional Chinese medicine (TCM) for the first time. Using the strategy of combining EEM fluorescence with second-order calibration method, i.e. parallel factor analysis (PARAFAC), the simultaneous quantification of scopoletin and scopolin in the complex system of Erycibe obtusifolia Benth was achieved successfully. The predicted concentrations were compared with the values obtained using high performance liquid chromatography-coupled to fluorimetric detector (HPLC-FLD), and no significant differences between them were observed. Therefore, the proposed methods using time-resolved fluorescence for qualitative analysis and EEMs coupled with second-order calibration for quantitative analysis in TCM are comparable and provide a suitable alternative to the chromatography-based method.

A facile water-stable MOF-based "off-on" fluorescent switch for label-free detection of dopamine in biological fluid.

As an emerging class of fluorescent probes, metal-organic frameworks (MOFs) have recently received great interest owing to their fascinating functional properties, intriguing tunable structures, high selectivity and good sensitivity. Herein, we present a novel strategy based on the application of a facile water-stable MOF {[Cd(µ3-abtz)·2I]}n (Abtz-CdI2-MOF, abtz = 1-(4-aminobenzyl)-1,2,4-triazole) using powerful solvo-thermal synthetic techniques, which can serve as an "off-on" fluorescent switch for the label-free detection of dopamine (DA) without any additional surface modification and functionalization. The fluorescence signal of Abtz-CdI2-MOF can be efficiently quenched by KMnO4, and then restored by DA in an "off-on" mode. The possible quenching mechanism should be static quenching resulting from the ground state recombination between Abtz-CdI2-MOF and MnO4 -. Further when DA is added, MnO4 - can be gradually released from the hybrid system, and bring about ground state complex decomposition, which is triggered by competitive interactions between Abtz-CdI2-MOF and the reduced iodine ions. Therefore, the fluorescence signal can be gradually turned "on". The relative intensity of restored fluorescence is proportional to the concentration of DA in the wide linear range of 0.25-50 µM with a low detection limit of 57 nM (S/N = 3). Additionally, some potentially foreign interfering substances, such as ascorbic acid (AA) and uric acid (UA), glucide, amino acids and metal ions did not affect DA determination significantly. The proposed strategy was also successfully applied for DA determination in biological samples with satisfactory recoveries from 94.5% to 102%.

Facile synthesis of red emitting 3-aminophenylboronic acid functionalized copper nanoclusters for rapid, selective and highly sensitive detection of glycoproteins.

As an emerging class of fluorescent probes, copper nanoclusters (Cu NCs) have been considered as an intriguing candidate for detecting biomoleculars due to their outstanding fluorescent properties, excellent biocompatibility and low cost. Herein, we fabricated bovine serum albumin (BSA) protected Cu NCs (BSA-Cu NCs) and further functionalized them with 3-aminophenylboronic acid (APBA) for selectively discerning glycoproteins. In aqueous solution, Cu(2+) ions were directly reduced into BSA-Cu NCs by hydrazine hydrate (N2H4·H2O) at room-temperature using BSA as the capping agent. The synthetic process was very rapid, simple and easy for controlling due to the lack of any other complicated procedure such as heating and adjusting the pH value of the reactive mixture. The APBA-Cu NCs showed strong fluorescent emission at 630nm in the red range. So it can effectively avoid the disturbance of auto-fluorescence in biosamples. The fluorescence of the APBA-Cu NCs was obviously quenched by glycoprotein samples. Then, the APBA-Cu NCs were employed as a probe for selective capture and sensitive detection of glycoproteins with a wide linear range of 5-220nM and a low detection limit of 2.60nM owing to the covalent reaction between the boric acid group of APBA and the cis-glycol groups of the glycoproteins. The developed method was also successfully applied to determine glycoproteins in egg white of chickens and human urine samples with quantitative spike recoveries from 95% to 104%.