Antimicrobial resistance (AMR) is one of the greatest threats to human health that, by 2050, will lead to more deaths from bacterial infections than cancer. New antimicrobial agents, both broad-spectrum and selective, that do not induce AMR are urgently required. Antimicrobial peptides (AMPs) are a novel class of alternatives that possess potent activity against a wide range of Gram-negative and positive bacteria with little or no capacity to induce AMR. This has stimulated substantial chemical development of novel peptide-based antibiotics possessing improved therapeutic index. This review summarises recent synthetic efforts and their impact on analogue design as well as their various applications in AMP development. It includes modifications that have been reported to enhance antimicrobial activity including lipidation, glycosylation and multimerization through to the broad application of novel bio-orthogonal chemistry, as well as perspectives on the direction of future research. The subject area is primarily the development of next-generation antimicrobial agents through selective, rational chemical modification of AMPs. The review further serves as a guide toward the most promising directions in this field to stimulate broad scientific attention, and will lead to new, effective and selective solutions for the several biomedical challenges to which antimicrobial peptidomimetics are being applied.

Chemically modified and conjugated antimicrobial peptides against superbugs.

Guanidinium-functionalized poly(arylene ether sulfone) anion exchange polymer electrolytes were synthesized via activated fluorophnyl-amine reaction, followed by the methylation with dimethyl sulfate. The activated fluorine-amine reaction gives precise control of cation functionality without the deleterious side reactions and allows the direct connection of guanidinium into stable phenyl rings.

Guanidinium-FunctionalizedAnionExchangePolymerElectrolytesvia Activated Fluorophenyl-Amine Reaction

Biofouling, as one of the membrane foulings, is the major obstacle limiting the application of polyamide (PA) thin-film composite (TFC) nanofiltration (NF) membranes in reclamation of wastewaters and treatment of industrial fluids. Herein, we introduced a facile and effective strategy for the modification of traditional PA-TFC NF membranes to improve water permeability and biofouling resistance. Specifically, three reactive guanidine molecules were successfully bonded onto the surface of PA-TFC membranes using chemical reactions between the amine groups of guanidine and the residual acyl chloride groups on the nascent PA-TFC membrane. The covalent attachment of guanidines can significantly enhance water permeability without compromising salt rejection. For instance, for 2 g L−1 Na2SO4 aqueous solution, the water flux of NFM2 increased from 25.2 L m−2 h−1 to 68.4 L m−2 h−1 at 25 °C and 0.6 MPa compared to the traditional piperazine (PIP)–trimesoyl chloride (TMC) membrane, while around 98.3%. Na2SO4 rejection was maintained. Moreover, the membranes were endowed with easy-cleaning properties, which can remarkably prevent foulant adhesion, with the water flux recovery ratio being as high as 98.9%. The developed TFC membranes also showed excellent anti-adhesive and antimicrobial activities against Gram-negative Escherichia coli K12 (E. coli), Gram-positive Bacillus pumilus LDS33 (B. pumilus) and Aspergillus parasiticus JFS (A. parasiticus). Therefore, the resultant guanidinium-functionalized NF membranes which have integrated high permselectivity and superior fouling resistance properties are promising materials for fabricating a new generation of anti-fouling/antimicrobial surfaces that are applicable to many applications such as water desalination and softening and wastewater treatment.

Guanidinium-functionalized nanofiltration membranes integrating anti-fouling and antimicrobial effects

A flexible poly(vinylidene difluoride) (PVDF) composite film embedding LiNbO3 ceramics decorated with silver nanoparticles (Ag NPs) has been synthesized using the solvent casting method. The polar β-phase, Ag NPs, and LiNbO3 phases were confirmed in the composite film using various characterization methods. The composite film showed promising degradation of cationic and anionic dyes using piezocatalysis under ultrasonication. Moreover, this composite film also effectively degraded two model pharmaceutical pollutants named tetracycline and ciprofloxacin using piezocatalysis under ultrasonication. In addition to this, this composite film piezocatalytically removed more than 99.999% of Escherichia coli and 96.65% of Staphylococcus aureus bacteria within 180 min of sonication. The piezocatalytic performance of the PVDF composite film embedding Ag-loaded LiNbO3 in all three applications was superior to that obtained in the case of the PVDF film embedding LiNbO3 and the bare PVDF film. This demonstrates the pronounced effect of Ag NPs in the increase of piezocatalytic activity in the composite film.

Flexible Ag@LiNbO3/PVDF Composite Film for Piezocatalytic Dye/Pharmaceutical Degradation and Bacterial Disinfection.

Reverse osmosis membranes with guanidine and amine enriched surface for biofouling and organic fouling control

A self-assembled aza-BODIPY linked dicyanostilbenzene with a large Stokes shift, AIE, mechanochromism and singlet oxygen yield

The invention belongs to the technical field of organic materials and discloses a dihydroxy fluorescence chain extender based on a carbazole derivative and preparation and application thereof. The method comprises the following steps: (1) under alkaline condition, an organic solvent is used as a reaction medium, carbazole and propargyl bromide react and subsequent processing is carried out to obtain an intermediate 9-propynyl carbazole; the molar ratio of carbazole to propargyl bromide is 1: 1.1-2; and (2) in the atmosphere of inert gas and in the presence of a catalyst and a reducing agent, the intermediate 9-propynyl carbazole and dihydroxy azide react in a solvent, and subsequent processing is carried out to obtain the dihydroxy fluorescence chain extender based on the carbazole derivative. The chain extender has high yield, has high fluorescence intensity and good anti-ultraviolet stability, and is used in manufacturing of a fluorescence WPU emulsion.

Dihydroxy fluorescence chain extender based on carbazole derivative and preparation and application thereof

Purpose




The purpose of this paper is to develop non-leaching and eco-friendly antimicrobial waterborne polyacrylates with excellent antibacterial properties by grafting antibacterial vinyl monomer, glycidyl methacrylate (GMA) modified polyhexamethylene guanidine hydrochloride (PHMG).




Design/methodology/approach




PHMG of different molecular weights were modified by GMA to synthesize antibacterial vinyl monomer, GMA-modified PHMG (GPHMG). Different content and molecular weights of GPHMG were used to synthesize antimicrobial waterborne polyacrylates through emulsion polymerization.




Findings




The addition of GPHMG gained by modifying PHMG showed little influence on thermal stability of the films, but decreased the glass transition temperature(Tg). Meanwhile, the tensile strength decreased, while the breaking elongation increased. The antibacterial properties of the antibacterial films with different GPHMG contents were studied, when GPHMG content was around 0.9 Wt.%, antibacterial films showed excellent antibacterial activity (antibacterial rate >= 99.99 per cent). When weight content of GPHMG in the films remained constant, antibacterial property of films increased first and then decreased with the increase of molecular weight of GPHMG. The structural antibacterial polymer film had more perdurable antibacterial activity than the blended one.




Research limitations/implications




The grafting efficiency of GPHMG to antimicrobial waterborne polyacrylates could be further improved.




Practical implications




Antimicrobial waterborne polyacrylates with excellent antibacterial properties can be used to antibacterial coating and adhesive.




Originality/value




The antibacterial properties of films with different molecular weight of GPHMG were studied, and the durability and stability of antibacterial properties between structural antimicrobial films and blended antimicrobial films were also investigated by ring-diffusion method.

Development of non-leaching and eco-friendly polyhexamethylene guanidine hydrochloride based antimicrobial waterborne polyacrylates

In one aspect, the present disclosure relates to click-functional antimicrobial molecules (including small molecules or, in some cases, macromolecules) and the construction of antimicrobial polymers such as polyurethanes, polyesters, and polyacrylates, including through the use of such molecules. In some cases, the antimicrobial click-functional molecules are based on 1,2-benzisothiazolin-3-one (BIT), trimethylguanidine or tetramethylguanidine (TMG), polyhexamethylene guanidine (PHMG), fluorine-containing molecules, or a combination thereof. For example, 1,2-benzisothiazolin-3-one (BIT) functionalized with an alkyne (BIT-Al), trimethylguanidine or tetramethylguanidine (TMG) functioned with an alkyne (TMG-Al) or dual alkynes (TMG-dAl), and/or polyhexamethylene guanidine (PHMG) functionalized with an alkyne (PHMG-Al) are described herein. Clickable antimicrobial polymers can be used to form coatings or films.

Clickable antimicrobial molecules and polymers

Construction of Guanidinium-rich Polymers and Their Applications

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