Redox phospholipid polymer microparticles as doubly functional polymer support for immobilization of enzyme oxidase

Recent Advances in Glucose Responsive Insulin Delivery Systems: Novel Hydrogels and Future Applications

Over the past several decades, there have been major advancements in the field of glucose sensing and insulin delivery for the treatment of type I diabetes mellitus. The introduction of closed-loop insulin delivery systems that deliver insulin in response to specific levels of glucose in the blood has shifted significantly the research in this field. These systems consist of encapsulated glucose-sensitive components such as glucose oxidase or phenylboronic acid in hydrogels, microgels or nanoparticles. Since our previous evaluation of these systems in a contribution in 2004, new systems have been developed. Important improvements in key issues, such as consistent insulin delivery over an extended period of time have been addressed. In this contribution, we discuss recent advancements over the last 5 years and present persisting issues in these technologies that must be overcome in order for these systems to be applicable in patients.

A review on phytoremediation of mercury contaminated soils

Mercury (Hg) and its compounds are one of the most dangerous environmental pollutants and Hg pollution exists in soils in different degrees over the world. Phytoremediation of Hg-contaminated soils has attracted increasing attention for the advantages of low investment, in-situ remediation, potential economic benefits and so on. Searching for the hyperaccumulator of Hg and its application in practice become a research hotspot. In this context, we review the current literatures that introduce various experimental plant species for accumulating Hg and aided techniques improving the phytoremediation of Hg-contaminated soils. Experimental plant species for accumulating Hg and accumulation or translocation factor of Hg are listed in detail. The translocation factor (TF) is greater than 1.0 for some plant species, however, the bioaccumulation factor (BAF) is greater than 1.0 for Axonopus compressus only. Plant species, soil properties, weather condition, and the bioavailability and heterogeneity of Hg in soils are the main factors affecting the phytoremediation of Hg-contaminated soils. Chemical accelerator kinds and promoting effect of chemical accelerators for accumulating and transferring Hg by various plant species are also discussed. Potassium iodide, compost, ammonium sulphate, ammonium thiosulfate, sodium sulfite, sodium thiosulfate, hydrochloric acid and sulfur fertilizer may be selected to promote the absorption of Hg by plants. The review introduces transgenic gene kinds and promoting effect of transgenic plants for accumulating and transferring Hg in detail. Some transgenic plants can accumulate more Hg than non-transgenic plants. The composition of rhizosphere microorganisms of remediation plants and the effect of rhizosphere microorganisms on the phytoremediation of Hg-contaminated soils are also introduced. Some rhizosphere microorganisms can increase the mobility of Hg in soils and are beneficial for the phytoremediation.

A review on control factors of pyrolysis technology for plants containing heavy metals

The treatment of plants with heavy metals, whether they grow naturally in heavy metal contaminated soil or are used for remediation of heavy metal contaminated soil has attracted increasing attention. Pyrolysis is often used for the disposal of plants with heavy metals because it stabilizes heavy metals effectively and produces biochar. The resulting products of pyrolysis are in the form of solid components (char and ash), liquid components (bio-oil and tar), together with gas components (condensable and non-condensable vapor gas). The metal amount in the char or liquid and gaseous phases can be maximized or minimized via treating a plant feedstock containing heavy metals under different conditions. In addition, the potential risk of biochar produced from plants after pyrolysis becomes a research hotspot in the field of pyrolysis technology of plants containing heavy metals. Herein, we review current literatures that emphasize the influencing factors on the metal content in the biochar, liquid and gaseous phases, as well as the potential risk of biochar.

Effect of the pyrolysis duration and the addition of zeolite powder on the leaching toxicity of copper and cadmium in biochar produced from four different aquatic plants

The study aimed to determine the biochar yield of four aquatic plants, the leaching toxicity of copper (Cu) and cadmium (Cd) in the biochar, and the stabilization characteristics of the biochar produced under different pyrolysis conditions (at 350 °C for 1, 2, and 3 h and absence/presence of zeolite powder). The results showed that different plant species required a different pyrolysis duration and the presence or absence of zeolite powder. The stabilization of Cu and Cd was significantly affected by the pyrolysis duration and the external materials for different plant species and different types of admixtures. Pyrolysis temperatures over 350 °C for 1 h without zeolite powder generated stable Cu and Cd in goldfish algae (Ceratophyllum demersum L.), foxtail algae (Myriophyllum verticillatum L.), and penny grass (Hydrocotyle vulgaris). Pyrolysis temperatures over 350 °C for 1 h with zeolite powder made Cu and Cd stable in water celery (Oenanthe javanica (Bl.) DC). The addition of zeolite powder during pyrolysis was possible due to the weight reduction efficiency in plants with Cu and Cd. Furthermore, the surface of the biochar with the zeolite powder showed honeycombs and a spongy porous structure. The duration of the pyrolysis had little effect on the honeycomb pore structure.

Effect of mixed solutions of heavy metal eluents on soil fertility and microorganisms

This study analyzed the effect of heavy metal eluents (0.3 mol/L C₆H₈O₇, 5 × 10^-4 mol/L EDTA, and 0.01 mol/L Na₂S₂O₃) on the content of organic matter, hydrolytic nitrogen, available phosphorus and potassium, and species composition of bacteria and fungi in vegetable soils. The obtained results documented that the treatment of the soil, consisting of shaking the sample with a mixture of eluents, significantly increased the content of organic matter, hydrolytic nitrogen, and available phosphorus and potassium. The mixed solutions of eluents increase the maximum available P in the soil by 279.3%, and hydrolytic N by 30.7%. The eluents affected, to a certain extent, the dominant species of microorganisms in the soil, but did not increase species richness and evenness in all soil samples.

Toxicity assessment of artificially added zinc, selenium, and strontium in water

The present research was to study the toxicology of artificially added Zn, Se and Sr in water. Specifically, we investigated the mortality and liver toxicity in zebrafish (Danio rerio), caused by different water concentrations of zinc sulfate (ZnSO₄), sodium selenite (Na₂SeO₃), and strontium chloride hexahydrate (6H₂O·SrCl₂). Adult and embryo-larval zebrafish were used in the experiment. Analysis was performed of mortality, liver area and impermeability, delayed absorption area of the yolk sac, and liver tissue structure. The concentration change of sodium selenite exerted the most significant effect on the mortality of adult zebrafish, followed by that of strontium chloride hexahydrate, and zinc sulfate. Elevated strontium chloride hexahydrate concentration was associated with liver toxicity in zebrafish in the preliminary experiment. However, embryo-larval zebrafish were observed to die when the concentration of Zn²⁺ or Se⁴⁺ increased to a certain extent, without obvious liver toxicity. Our results indicated strontium chloride hexahydrate was hepatotoxic to embryo-larval zebrafish, which was manifested mainly as hepatomegaly and delayed absorption of the yolk sac. In addition, the artificially added strontium chloride hexahydrate destroyed liver tissue structure, resulting in hepatocyte enlargement, cell nucleus enlargement, blurred cytoplasmic boundaries, and formation of a vacuolar liver. These findings suggest the amount of strontium chloride hexahydrate added in soft drinks should be limited to certain levels.

Ultralow Fouling and Functionalizable Surface Chemistry Based on Zwitterionic Carboxybetaine Random Copolymers

Here, we report a simple yet effective surface-modification approach to imparting hydrophobic surfaces with superhydrophilicity using ultralow fouling/functionalizable carboxybetaine (CB) copolymers via a dip-coating technique. A new series of CB random copolymers with varying amphiphilicities were synthesized and coated on hydrophobic polypropylene (PP) and polystyrene (PS) surfaces. The nonfouling capability of each coating was screened by an enzyme-linked immunosorbent assay (ELISA) and further comprehensively assessed against 100% human serum by a Micro BCA protein assay kit. The random copolymer containing ∼30 mol % CB units showed superhydrophilicity with the highest air contact angle of more than 165° in DI water and the best nonfouling capability against 100% human blood serum. Surfaces of a 96-well plate coated with the optimal CB random copolymer had a significantly better nonfouling capability than those of a commercial 96-well plate with an ultralow attachment surface. The adhesion of mouse embryonic fibroblast cells (NIH3T3) was completely inhibited on surfaces coated with CB random copolymers. Furthermore, the optimal nonfouling CB copolymer surface was functionalized with an antigen via covalent bonding where its specific interactions with its antibody were verified. Thus, this CB random copolymer is capable of imparting both ultralow fouling and functionalizable capabilities to hydrophobic surfaces for blood-contacting devices.

Enhancer assisted-phytoremediation of mercury-contaminated soils by Oxalis corniculata L., and rhizosphere microorganism distribution of Oxalis corniculata L

The present study investigated remediation of mercury-contaminated soils using Oxalis corniculata L. combined with various enhancers (sodium thiosulfate, ammonium thiosulfate, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid). The experiment was conducted using Oxalis corniculata seedlings planted in pots containing mercury loaded soils. Investigations included analysis of soil properties, plant growth conditions, ability of the plants to accumulate and extract mercury, and rhizosphere microorganism distribution. The maximal mercury content of the aerial parts and the mercury-translocation ratio of Oxalis corniculata treated with enhancers increased compared to Oxalis corniculata without enhancers. Compared with no enhancers, the theoretical reduction in phytoremediation time was about 50%, 25%, 20% and 21% when Oxalis corniculata was treated with sodium thiosulfate (Na₂S₂O₃), ammonium thiosulfate ((NH₄)₂S₂O₃), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), respectively. The results indicated that the dominant species in rhizosphere soils varied with different enhancers. However, the evenness of background soils, rhizosphere soils of Oxalis corniculata, Oxalis corniculata treated with Na₂S₂O₃, (NH₄)₂S₂O₃, EDTA and DTPA was not largely different at 0.62, 0.61, 0.57, 0.64, 0.61 and 0.63, respectively. These findings demonstrate that Oxalis corniculata treated with Na₂S₂O₃ has the potential to recover and reclaim mercury-contaminated soils in pots.

Effects of growth agents and mercury on several herbs

The paper discussed the effects of growth agents and mercury on the growth of four herb species subjected to a pot experiment: Aloe vera, Setcreasea purpurea, Chlorophytum comosum, and Oxalis corniculata. We determined the height and biomass production of selected plants treated with different growth agents and different concentrations of mercury solutions. We evaluated the relative growth rate (RGR) of the experimental plants. The aim of the study was to explore potential novel solutions to the shortcoming of the low speed of phytoremediation. The results showed that the upper parts of Aloe vera and Chlorophytum comosum had the fastest growth in the treatment with water only. In contrast, the upper parts of Setcreasea purpurea grew most intensely after the treatment with Lvyebao Fertilizer, whereas the aboveground parts of Oxalis corniculata had the fastest growth after the application of water and the occasional use of Green Cake Fertilizer. In addition, the tolerance to mercury of Oxalis corniculata was the strongest, whereas that of Chlorophytum comosum was the lowest among the species investigated.

Photoreactive Polymers Bearing a Zwitterionic Phosphorylcholine Group for Surface Modification of Biomaterials

Photoreactive polymers bearing zwitterionic phosphorylcholine and benzophenone groups on the side chain were synthesized and used as surface modification reagents for biomaterials. A photoreactive methacrylate containing the benzophenone group, 3-methacryloyloxy-2-hydroxypropyl-4-oxybenzophenone (MHPBP), was synthesized via a ring-opening and addition reaction between glycidyl methacrylate and 4-hydroxybenzophenone. Then, water-soluble, amphiphilic polymers poly(2-methacryloyloxyethyl phosphorylcholine (MPC)-co-MHPBP) (PMH) and poly(MPC-co-n-butyl methacrylate-co-MHPBP), with different monomer unit compositions, were synthesized through radical polymerization. Ultraviolet-visible (UV/vis) absorption spectra of these polymer solutions showed that these polymers have maximum absorption peaks at 254 and 289 nm that can be attributed to the benzophenone unit. The intensity of UV adsorption at 289 nm was decreased with increased UV irradiation time, and it was saturated within a few minutes, indicating that the polymers are highly sensitive to UV irradiation. A commercial material (i.e., cyclic polyolefin) was simply modified by a UV irradiation for 1.0 min. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis results indicated that the stability of the polymer on the surface was dramatically enhanced because of the photochemical reaction of the benzophenone moiety. The air contact angles of PMH surfaces measured in water were up to 160°. Thus, highly hydrophilic surfaces were obtained. The critical surface tension of the PMH-modified surface was 45.7 mN/m. By evaluating the biological reactivity of the treated surface, protein adsorption and cell adhesion were completely inhibited on the surface, which was prepared using a photopatterning procedure using PMH. In conclusion, photoreactive MPC polymers with a benzophenone moiety could be used as a novel and effective surface modifier.

Cell-membrane-permeable and cytocompatible phospholipid polymer nanoprobes conjugated with molecular beacons

To enable the visualization of the distribution and dynamics of intracellular biomolecules and thereby understand the mechanisms of intracellular bioreactions, we developed a specific functional nanoprobe through the combination of a well-designed, cytocompatible phospholipid polymer and molecular beacons (MBs). A water-soluble, amphiphilic phospholipid polymer, poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)-co-N-succinimidyloxycarbonyl tetra(ethylene glycol) methacrylate] (PMBS), was synthesized and conjugated with MBs to form nanoprobes via a chemical reaction between the ester group of N-hydroxysuccinimide and the amine group of the MBs. Surface tension measurements indicated that the polymeric nanoprobes had different conformations in aqueous solution, specifically at a concentration of 1.0 mg/mL. The PMBS, containing the large, hydrophobic BMA, formed polymer aggregates. The carcinoma cells used to test the probes remained 100% viable after incubation with PMBS-MB probes. The polymeric nanoprobes demonstrated not only a high target specificity but also resistance to nonspecific adsorption of proteins compared with unconjugated MBs and were able to penetrate the cytoplasm of the cells, allowing the live imaging of mRNA. In summary, MPC polymer-MB nanoprobes have great potential for practical application for the noninvasive monitoring of intracellular biomolecules and bioreactions in real time.