The heterologous expression of CmBBX22 delays leaf senescence and improves drought tolerance in Arabidopsis.

KEY MESSAGE: CmBBX22, a transcription factor of chrysanthemum, was verified to confer drought tolerance in Arabidopsis thaliana. The BBX proteins are known to operate as regulators of plant growth and development, but as yet their contribution to the abiotic stress response has not been well defined. Here, the chrysanthemum BBX family member CmBBX22, an ortholog of AtBBX22, was found to be transcribed throughout the plant, although at varying intensity, and was induced by imposing moisture deficiency via exposure to polyethylene glycol. The heterologous, constitutive expression of this gene in Arabidopsis thaliana compromised germination and seedling growth, but enhanced the plants' ability to tolerate drought stress. In transgenic plants challenged with abscisic acid, leaf senescence was delayed and the senescence-associated genes and chlorophyll catabolic genes SAG29, NYE1, NYE2 and NYC1 were down-regulated. We speculated that CmBBX22 may serves as a regulator in mediating drought stress tolerance and delaying leaf senescence.

A Biodegradable Trilayered Barrier Membrane Composed of Sponge and Electrospun Layers: Hemostasis and Antiadhesion.

Placing a physical barrier between the injured site and the adjacent tissues is a very common and highly effective approach to prevent abdominal adhesions in these days. A biodegradable trilayered barrier was fabricated to prevent formation of abdominal adhesions, in which a poly(lactide-co-glycolide)/poly(lactide)-b-poly(ethylene glycol) (PLGA/PLA-b-PEG) electrospun layer was sandwiched between layers of carboxymethyl chitosan (CMCS) sponge. The hydrophilic CMCS sponge layers with glycerin (GL) could adhere to the surface of wound easily, and present great hemostatic capability. The mechanism of the formation of adhesion related to blood clots acting with fibroblast cells was evaluated in detail. The blood clot acted as a "medium" inducing the fibroblast cells growth and proliferation, but had no special attraction on epithelial cells. CMCS sponge layer took away the blood clots during the swelling and dissolution stages. The electrospun layer promoted the growth of epithelial cells, but exhibited inhibition on the adhesion and spread of fibroblast cells, which ensured excellent effect of adhesion prevention. Evaluated by a rat model of sidewall defect-bowel abrasion, significant reductions of postoperative adhesion in its level and occurrence were observed in animals treated by the trilayered barrier.

A Novel Polyurethane-Based Polyion Complex Material with Tunable Selectivity against Interferents for Selective Dopamine Determination.

Polyion complex (PIC) materials have been widely used in biosensors due to their molecular selectivity. However, achieving both widely controllable molecular selectivity and long-term solution stability with traditional PIC materials has been challenging due to the different molecular structures of polycations (poly-C) and polyanions (poly-A). To address this issue, we propose a novel polyurethane (PU)-based PIC material in which the main chains of both poly-A and poly-C are composed of PU structures. In this study, we electrochemically detect dopamine (DA) as the analyte and L-ascorbic acid (AA) and uric acid (UA) as the interferents to evaluate the selective property of our material. The results show that AA and UA are significantly eliminated, while DA can be detected with a high sensitivity and selectivity. Moreover, we successfully tune the sensitivity and selectivity by changing the poly-A and poly-C ratios and adding nonionic polyurethane. These excellent results were employed in the development of a highly selective DA biosensor with a detection range from 500 nM to 100 µM and a 3.4 µM detection limit. Overall, our novel PIC-modified electrode has the potential to advance biosensing technologies for molecular detection.

Mechanism of a long-term controlled drug release system based on simple blended electrospun fibers.

BACKGROUND: Drug delivery systems based on electrospun fibers have been under development for many years. However, studies of controllable long-term drug release from electrospun membrane systems and the underlying release mechanisms have seldom been reported. METHODS: In this study, electrospun membrane drug delivery systems consisting of the antibiotic ciprofloxacin hydrochloride and FDA-approved polymers are fabricated. Different second-component polymers are introduced to change the properties of a poly(d,l-lactide-co-glycolide) (PLGA) matrix, thereby altering the drug release behavior. On the basis of observations of morphology, cumulative release profiles, and determinations of release duration, the drug release kinetics and critical characteristics influencing drug release behavior are discussed. RESULTS: It is found that the drug release profiles can be divided into three stages according to the rate of drug release. Stage I is controlled by fiber swelling and diffusion according to Fick's second law. Stage II is controlled by diffusion through a fused membrane structure, which results in very slow drug release. Stage III is controlled by polymer degradation and involves release of the remaining drug. CONCLUSIONS: The results of this study of release mechanisms should provide a basis for adjustments of drug release dosage and duration, thereby contributing to the development of drug delivery systems satisfying clinical requirements.

Jacket-free stir bar sorptive extraction with bio-inspired polydopamine-functionalized immobilization of cross-linked polymer on stainless steel wire.

Stainless steel wire (SSW) is a good substrate for stir bar sorptive extraction (SBSE). However, it is still a challenge to immobilize commonly used cross-linked polymers onto SSW. In this work, we present a new approach for immobilization of the cross-linked organic polymer onto SSW for jacket-free SBSE. A dopamine derivative was firstly synthesized; by introducing a mussel-inspired polydopamine process, a stable coating layer was finally generated on the surface of SSW. Secondly, the cross-linked polymer was synthesized on the polydopamine-modified SSW by using acetonitrile as the porogen, acrylamide (AA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker and 2,2'-azobis (2-methylpropionitrile) as the initiator. A diluted pre-polymerization solution was carefully prepared to generate a thin layer of the polymer. The prepared poly(EGDMA-AA)-modified stir bar showed high stability and good tolerance toward stirring, ultrasonication, organic solvents, and strong acidic and basic conditions. Morphology and structure characterization of coatings were performed by scanning electron microscopy and Fourier transform infrared spectra, respectively. The prepared poly(EGDMA-AA)-modified stir bar showed great extraction efficiency toward protoberberines, with enrichment factors of 19-42. An SBSE-HPLC method was also developed for quantitative analysis of protoberberines. The method showed low limits of detection (0.06-0.15 ng mL(-1)), wide linear range (0.5-400 ng mL(-1)), good linearity (R≥0.9980) and good reproducibility (RSD≤3.60% for intra-day, RSD≤4.73% for inter-day). The developed method has been successfully applied to determine protoberberines in herb and rat plasma samples, with recoveries of 88.53-114.61%.

Controlled Antibiotics Release System through Simple Blended Electrospun Fibers for Sustained Antibacterial Effects.

Implantation of sustained antibacterial system after abdominal surgery could effectively prevent complicated intra-abdominal infection. In this study, a simple blended electrospun membrane made of poly(D,L-lactic-co-glycolide) (PLGA)/poly(dioxanone) (PDO)/Ciprofloxacin hydrochloride (CiH) could easily result in approximately linear drug release profile and sustained antibacterial activity against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The addition of PDO changed the stack structure of PLGA, which in turn influenced the fiber swelling and created drug diffusion channels. It could be a good candidate for reducing postoperative infection or be associated with other implant to resist biofilm formation.

[Methoxypolyethylene glycol-modified HLA-A2 antigen on lymphocytes].

OBJECTIVE: To modify the HLA-A2 antigen on the lymphocytes with methoxypolyethylene glycol (mPEG) so as to block the specific binding site for antibody. METHOD: Different types of mPEG (all with final concentration of 12 mmol/L) were used at different temperatures in PBS with varied pH values for the modification of the HLA-A2 antigen. RESULT: The modification of the antigen was not obviously affected when it was carried out at 4 degrees Celsius or room temperature, but higher temperatures of 30 and 37 degrees Celsius significantly hampered the modification. Better antigen modification was observed with high-concentration mPEG in basic PBS, depending also on the type of mPEGs used for this purpose. CONCLUSION: The specific HLA-A2 binding on the lymphocytes is completely blocked by benzotriazole carbonate-mPEG(mPEG-BTC), which is superior to N-hydroxysuccinimidyl ester of mPEG(mPEG-SPA). Maleimide-mPEG(mPEG-MAL) is incapable of blocking the HLA-A2 ligand-binding site with antibody.

Adsorptive behavior and solid-phase microextraction of bare stainless steel sample loop in high performance liquid chromatography.

In this work, we interestingly happened to observe the adsorption of stainless steel sample loop of HPLC. The adsorptive behaviors of the stainless steel loop toward different kinds of compounds were studied, including polycyclic aromatic hydrocarbons (PAHs), halogeno benzenes, aniline derivatives, benzoic acid derivatives, phenols, benzoic acid ethyl ester, benzaldehyde, 1-phenyl-ethanone and phenethyl alcohol. The adsorptive mechanism was probably related to hydrophobic interaction, electron-rich element-metal interaction and hydrogen bond. Universal adsorption of stainless steels was also testified. Inspired by its strong adsorptive capability, bare stainless steel loop was developed as a modification-free in-tube device for solid-phase microextraction (SPME), which served as both the substrate and sorbent and possessed ultra-high strength and stability. Great extraction efficiency toward PAHs was obtained by stainless steel loop without any modification, with enrichment factors of 651-834. By connecting the stainless steel loop onto a six-port valve, an online SPME-HPLC system was set up and an SPME-HPLC method has been validated for determination of PAHs. The method has exceptionally low limits of detection of 0.2-2pg/mL, which is significantly lower than that of reported methods with different kinds of sorbents. Wide linear range (0.5-500 and 2-1000pg/mL), good linearity (R(2)≥0.9987) and good reproducibility (RSD≤2.9%) were also obtained. The proposed method has been applied to determine PAHs in environmental samples. Good recoveries were obtained, ranging from 88.5% to 93.8%.