Facile Construction of Carboxyl-Functionalized Ionic Polymer towards Synergistic Catalytic Cycloaddition of Carbon Dioxide into Cyclic Carbonates.

The development of bifunctional ionic polymers as heterogeneous catalysts for effective, cocatalyst- and metal-free cycloaddition of carbon dioxide into cyclic carbonates has attracted increasing attention. However, facile fabrication of such polymers having high numbers of ionic active sites, suitable types of hydrogen bond donors (HBDs), and controlled spatial positions of dual active sites remains a challenging task. Herein, imidazolium-based ionic polymers with hydroxyl/carboxyl groups and high ionic density were facilely prepared by a one-pot quaternization reaction. Catalytic evaluation demonstrated that the presence of HBDs (hydroxyl or carboxyl) could enhance the catalytic activities of ionic polymers significantly toward the CO2 cycloaddition reaction. Among the prepared catalysts, carboxyl-functionalized ionic polymer (PIMBr-COOH) displayed the highest catalytic activity (94% yield) in the benchmark cycloaddition reaction of CO2 and epichlorohydrin, which was higher than hydroxyl-functionalized ionic polymer (PIMBr-OH, 76% yield), and far exceeded ionic polymer without HBDs groups (PIMBr, 54% yield). Furthermore, PIMBr-COOH demonstrated good recyclability and wide substrate tolerance. Under ambient CO2 pressure, a number of epoxides were smoothly cycloadded into cyclic carbonates. Additionally, density functional theory (DFT) calculation verified the formation of strong hydrogen bonds between epoxide and the HBDs of ionic polymers. Furthermore, a possible mechanism was proposed based on the synergistic effect between carboxyl and Br- functionalities. Thus, a facile, one-pot synthetic strategy for the construction of bifunctional ionic polymers was developed for CO2 fixation.

Adhesive polyethylene glycol-based hydrogel patch for tissue repair.

Polyethylene glycol (PEG)-based tissue glue has been widely used in surgery, but the sealants were weak in strength and could not be in place of sutures. This paper prepared a PEG-based tissue patch made of F127-DA hydrogel and PEG-DA as adhesive. For the patch adhesion on tissues, photoinitiator of lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP, 0.1 % w/v) and UV flashlight at 395 nm for 30 s irradiation was used. The adhesion energy on pig skin, lung, heart, liver, kidney and stomach was 85.33, 56.40, 75.56, 70.22, 66.67 and 36.89 N/m, indicating the well stitching to different tissues. The hydrogel patch could also seal the punched tissues to prevent the leakage of liquid or air. Finally, the patch showed good tissue compatibility after 2 days adhesion on pig skin. In this regard, the hydrogel patch is expected to repair the wounded tissues without suture, being a biocompatible adhesive for wound healing of various tissues.

SERS-based boronate affinity biosensor with biomimetic specificity and versatility: Surface-imprinted magnetic polymers as recognition elements to detect glycoproteins.

Glycoproteins are a class of proteins with significant biological functions and clinical implications. Due to glycoproteins' reliability for the quantitative analysis, they have been used as biomarkers and therapeutic targets for disease diagnosis. We propose a sandwich structure-based boronate affinity biosensor that can separate and detect target glycoproteins by magnetic separation and Surface-enhanced Raman scattering (SERS) probes. The biosensor relies on boronic acid affinity magnetic molecularly imprinted polymer (MMIPs) with pH response as "capturing probe" for glycoproteins, and Au-MPBA@Ag modified with 4-mercaptophenylboronic acid (MPBA) as SERS probes, among which, MPBA has both strong SERS activity and can specifically recognize and bind to glycoproteins. MMIPs ensured specific and rapid analysis, and SERS detection provided high sensitivity. The proposed boronate affinity SERS strategy exhibited universal applicability and provided high sensitivity with limit of detection of 0.053 ng/mL and 0.078 ng/mL for horseradish peroxidase and acid phosphatase, respectively. Ultimately, the boronate affinity SERS strategy was successfully applied in detection of glycoprotein in spiked serum sample with recovery between 90.6% and 103.4%, respectively. In addition, this study used a portable Raman meter, which can meet the requirements of point-of-care testing. The biosensor presented here also has advantages in terms of cost-effectiveness, stability, and detection speed.

Non-swelling hydrogel-based microfluidic chips.

Hydrogel-based microfluidic chips are more biologically relevant than conventional polydimethylsiloxane (PDMS) chips, but the inherent swelling of hydrogels leads to a decrease in mechanical performance and deformation of the as-prepared structure in their manufacture and application processing. Non-swelling hydrogel has, for the first time, been utilized to construct microfluidic chips in this study. It was fabricated by covalently cross-linking the biocompatible copolymer of di-acrylated Pluronic F127 (F127-DA). Thanks to their non-swelling property, the hydrogel-based microfluidic chips maintain their as-prepared mechanical strength and channel morphology when equilibrated in aqueous solution at 37 °C. Moreover, the microfluidic chips are autoclavable and show an appropriately slow degradation rate by remaining stable within 21 days of incubation. Based on these properties, a vessel-on-a-chip was established by seeding human umbilical vein endothelial cells (HUVECs) onto the microchannel surfaces inside the microfluidic chip. Under 6 days of perfusion culture with a physiologically relevant shear stress of 5 dyne per cm2, the HUVECs in the chip show responsivity to fluid shear stress and express higher endothelial functions than the corresponding static culture. Therefore, non-swelling hydrogel-based microfluidic chips could potentially be applicable for cell/tissue-related applications, performing much better than conventional PDMS or existing hydrogel based microfluidic chips.

Effects of exogenous protein-like precursors on humification process during lignocellulose-like biomass composting: Amino acids as the key linker to promote humification process.

The aim of this study is to assess the effectiveness of protein-like precursors addition on promoting humification process during lignocellulose-like biomass composting through adding amino acids to compost. The humification indexes of R1 and R2 was significantly higher than that of CK (P < 0.05). The decreasing ratio of Maillard precursor concentration of R2 and R1 was higher than CK. Amino acids addition affected the bacteria community and environmental factors during composting. Variance partitioning analysis showed that humification process was strengthened with environmental factors, bacteria community, Maillard precursors. Structural equation model (SEM) analysis showed that amino acids had substantial impact on promoting humic acid (HA) formation. The combined application of protein-like wastes and lignocellulose-like wastes was suggested to improve carbon sequestration. This study lays a foundation for economically and effectively managing different types of straws by composting.