Progress in Solvent-Based Recycling of Polymers from Multilayer Packaging.

Conversion of chemical feedstocks derived from fossil fuels to virgin polymer, manufacturing of plastics in coal-dependent economies, and increasing consumption of virgin polymers for plastics packaging contribute significantly to environmental issues and the challenges we face. Nowadays, promoting sustainable development has become the consensus of more and more countries. Among them, the recycling of multilayer packaging is a huge challenge. Due to the complexity of its structure and materials, as well as the limitations of existing recycling frameworks, currently, multilayer packaging cannot be commercially recycled thus resulting in a series of circular economy challenges. It is undeniable that multilayer packaging offers many positive effects on products and consumers, so banning the use of such packaging would be unwise and unrealistic. Developing the appropriate processes to recycle multilayer packaging is the most feasible strategy. In recent years, there have been some studies devoted to the recycling process of multilayer packaging. Many of the processes being developed involve the use of solvents. Based on the recycled products, we categorised these recycling processes as solvent-based recycling, including physical dissolution and chemical depolymerisation. In physical dissolution, there are mainly two approaches named delamination and selective dissolution-precipitation. Focusing on these processes, this paper reviews the solvents developed and used in the last 20 years for the recycling of polymers from multilayer packaging waste and gives a summary of their advantages and disadvantages in terms of cost, product quality, ease of processing, and environmental impact. Based on existing research, one could conclude that solvent-based recycling methods have the potential to be commercialised and become part of a standard recycling process for polymer-based multilayer packaging. The combined use of multiple solvent-based recycling processes could be a breakthrough in achieving unified recycling of multilayer packaging with different components.

Carbon nanosol promotes plant growth and broad-spectrum resistance.

Carbon nanosol (CNS) is a carbon-based nanomaterial capable of promoting plant growth while the underlying mechanism involved in this process remains unknown. This study demonstrates that CNS promotes rice seedling growth under restricted concentrations. Macroelement transporter mutants were investigated to further investigate the CNS-mediated promotion of rice seedling growth. The genetic and physiological findings revealed that nitrate transporter 1.1B (NRT1.1B) and ammonium transporter 1 (AMT1) mutants inhibited the CNS-induced growth development of rice seedlings, whereas potassium transporter (AKT1) and phosphate transporter 8 (PT8) did not exhibit any inhibitory effects. Further investigations demonstrated the inhibition of CNS-mediated growth promotion via glutamine synthetase 1;1 (gs1;1) mutants. Additionally, the administration of CNS resulted in enhanced accumulation of chlorophyll in plants, and the promotion of CNS-induced growth was inhibited by yellow-green leaf 8 (YGL8) mutants and the chlorophyll biosynthetic gene divinyl reductase (DVR) mutants. According to these findings, the CNS promotes plant growth by stimulating chlorophyll biosynthesis. Furthermore, the presence of CNS enhanced the ability of rice to withstand blast, sheath blight (ShB), and bacterial blight. The nrt1.1b, amt1, dvr, and ygl8 mutants did not exhibit a broad spectrum effect. The positive regulation of broad-spectrum resistance in rice by GS1;1 suggests the requirement of N assimilation for CNS-mediated broad-spectrum resistance. In addition, an in vitro assay demonstrated that CNS inhibits the growth of pathogens responsible for blast, ShB, and bacterial blight, namely Magnaporthe oryzae, Rhizoctonia solani AG1-IA, and Xanthomonas oryzae pv. Oryzae, respectively. CNS application may also induce broad-spectrum resistance against bacterial and fungal pathogens, indicating that in addition to its antifungal and antibacterial properties, CNS application may also stimulate N assimilation. Collectively, the results indicate that CNS may be a potential nano-therapeutic agent for improved plant growth promotion while also providing broad-spectrum resistance.

Rational Design of Potent α-Conotoxin PeIA Analogues with Non-Natural Amino Acids for the Inhibition of Human α9α10 Nicotinic Acetylcholine Receptors.

α-Conotoxins (α-CTxs) are structurally related peptides that antagonize nicotinic acetylcholine receptors (nAChRs), which may serve as new alternatives to opioid-based treatment for pain-related conditions. The non-natural amino acid analogues of α-CTxs have been demonstrated with improved potency compared to the native peptide. In this study, we chemically synthesized Dab/Dap-substituted analogues of α-CTx PeIA and evaluated their activity at heterologously expressed human α9α10 nAChRs. PeIA[S4Dap, S9Dap] had the most potent half-maximal inhibitory concentration (IC50) of 0.93 nM. Molecular dynamic simulations suggested that the side chain amino group of Dap4 formed additional hydrogen bonds with S168 and D169 of the receptor and Dap9 formed an extra hydrogen bond interaction with Q34, which is distinctive to PeIA. Overall, our findings provide new insights into further development of more potent analogues of α-CTxs, and PeIA[S4Dap, S9Dap] has potential as a drug candidate for the treatment of chronic neuropathic pain.

Structure-based design and structure-activity relationships of 1,2,3,4-tetrahydroisoquinoline derivatives as potential PDE4 inhibitors.

This paper describes our medicinal chemistry efforts on 7-(cyclopentyloxy)-6-methoxy1,2,3,4-tetrahydroisoquinoline scaffold: design, synthesis and biological evaluation using conformational restriction approach and bioisosteric replacement strategy. Biological data revealed that the majority of the synthesized compounds of this series displayed moderate to potent inhibitory activity against PDE4B and strong inhibition of LPS-induced TNFα release. Among them, compound 19 exhibited the strongest inhibition against PDE4B with an IC50 of 0.88 µM and 21 times more potent selectivity toward PDE4B over PDE4D when compared to rolipram. A primary structure-activity relationship study showed that the attachment of CH3O group or CF3O group to the phenyl ring at the para-position was helpful to enhance the inhibitory activity against PDE4B. Moreover, sulfonamide group played a key role in improving the inhibitory activity against PDE4B and subtype selectivity. In addition, the attachment of the additional rigid substituents at the C-3 position of 1,2,3,4-tetrahydroisoquinoline ring was favored to subtype selectivity, which was consistent well with the observed docking simulation.