Sustainable Strategies for Synthesizing Lignin-Incorporated Bio-Based Waterborne Polyurethane with Tunable Characteristics.

In this study, we introduce a novel approach for synthesizing lignin-incorporated castor-oil-based cationic waterborne polyurethane (CWPU-LX), diverging significantly from conventional waterborne polyurethane dispersion synthesis methods. Our innovative method efficiently reduces the required solvent quantity for CWPU-LX synthesis to approximately 50% of that employed in traditional WBPU experimental procedures. By incorporating lignin into the polyurethane matrix using this efficient and reduced-solvent method, CWPU-LX demonstrates enhanced properties, rendering it a promising material for diverse applications. Dynamic interactions between lignin and polyurethane molecules contribute to improved mechanical properties, enhanced thermal stability, and increased solvent resistance. Dynamic interactions between lignin and polyurethane molecules contribute to improved tensile strength, up to 250% compared to CWPU samples. Furthermore, the inclusion of lignin enhanced thermal stability, showcasing a 4.6% increase in thermal decomposition temperature compared to conventional samples and increased solvent resistance to ethanol. Moreover, CWPU-LX exhibits desirable characteristics such as protection against ultraviolet light and antibacterial properties. These unique properties can be attributed to the presence of the polyphenolic group and the three-dimensional structure of lignin, further highlighting the versatility and potential of this material in various application domains. The integration of lignin, a renewable and abundant resource, into CWPU-LX exemplifies the commitment to environmentally conscious practices and underscores the significance of greener materials in achieving a more sustainable future.

Enhanced antimicrobial and antifungal property of two-dimensional fibrous material assembled by N-halamine polymeric electrolytes.

Microbial contamination and biofilm formation cause serious issues in medical, household, industrial and environmental applications. In this study, a series of cationic and anionic N-halamine polymeric precursors, poly (N,N-dimethyl-N-decyl ammonium ethyl methacrylate-co-methacrylamide) (PQDM) and poly (acrylic acid-co-methacrylamide) (PAM), were synthesized and coated onto cotton fabrics through the layer-by-layer (LBL) assembly technique. The coated LBL cotton swatches were characterized by Scanning Electron Microscopy, Fourier transform infrared spectroscopy, and contact angle evaluation. The stability of the LBL samples towards artificial sweat and home laundering was evaluated. The LBL treated fabrics demonstrated effective antimicrobial efficacy and biofilm-controlling against Gram-positive bacteria, Gram-negative bacteria, and Fungi. In vitro cytocompatibility test towards mouse fibroblast cell indicated that the LBL coated cotton fabrics are cytocompatible, pointing to great potentialities of the LBL assembled fabrics for future biomedical applications.

Structural insights into conformation of amphiphilic quaternary ammonium chitosans to control fungicidal and anti-biofilm functions.

Fungal biofilm formation is an emerging problem in a wide range of health-related applications. This study aims to design and synthesize amphiphilic quaternary ammonium chitosans (AQACs) that could bind onto fungal biofilms to kill adherent fungal cells, and establish their structural/fungicidal activity relationships. AQACs with different hydrophobic alkyl chain length (C4, C8, and C12) were synthesized by quaternization of 3-bromopropionic acid with the corresponding tertiary amines, followed by reacting with chitosan using the EDC/NHS chemistry. The new AQACs were soluble in water, yet formed self-aggregates in the solution with different sizes. In antifungal tests against free-floating Candida albicans, shorter alkyl chains (C4) in the AQACs resulted in the most potent fungicidal effect. However, in the treatment of Candida biofilms formed on solid surfaces, AQACs with longer alkyl chains (C8 and C12) were much more effective than their shorter chain counterpart (C4). The effects of alkyl chain self-aggregation on the opposite trend in fungicidal and anti-biofilm activities were discussed. All the AQACs showed excellent cytocompatibility with mammalian cells.

Amphiphilic quaternary ammonium chitosans self-assemble onto bacterial and fungal biofilms and kill adherent microorganisms.

Formation of biofilms on solid surfaces is a long-standing challenge to multiple medical and health-related applications. Once formed, biofilms are very difficult to destroy, and microorganisms in biofilms are much more resistant to antimicrobial agents than their free-floating counterparts. The current antimicrobial agents/disinfectants often have low residence time on biofilms, leading to low antimicrobial effect on biofilm microorganisms. We designed and synthesized an amphiphilic quaternary ammonium chitosan (CS612) as biocompatible antimicrobial agents that bind onto preformed biofilms to kill adherent microorganisms. CS612 was synthesized through an external acid-free approach, and showed excellent concentration-dependent cytocompatibility toward mammalian cells. Antimicrobial functions of CS612 were confirmed by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests against Gram-positive bacteria, Gram-negative bacteria, and fungi. CS612 rapidly bound onto preformed bacterial and fungal biofilms, and killed adherent microorganisms living in the biofilms. The biofilm-binding kinetic parameters were determined, pointing to a new strategy to manage microorganisms in biofilms and their accompanying problems.

Amphiphilic quaternary ammonium chitosan/sodium alginate multilayer coatings kill fungal cells and inhibit fungal biofilm on dental biomaterials.

Formation of fungal biofilms on health care-related materials causes serious clinical consequences. This study reports a novel fungal repelling strategy to control fungal biofilm formation on denture biomaterials through layer-by-layer self-assembly (LBL). Amphiphilic quaternary ammonium chitosans (CS612) were synthesized and used as the antimicrobial positive layer, and sodium alginate (SA) was chosen as the negative layer to construct LBL multilayers on poly (methyl methacrylate) (PMMA)-based denture materials. The presence of LBL multilayers on denture disc was confirmed and characterized by surface zeta potential, water contact angle, AFM, and FT-IR analyses. The multilayer coatings, especially CS612 as the outmost layer, effectively prevented the fungal initial adhesion and biofilm formation. The Candida cells avoided the multilayer coatings and suspended in broth solution instead of forming biofilms, suggesting that the LBL multilayers had fungal repelling effects. The LBL multilayers were biocompatible toward mammalian cells. In stability tests, after immersion in PBS for 4 weeks under constant shaking and repeated brushing with a denture brush for up to 3000 times, the biofilm-controlling effects of the LBL multilayers were not affected, pointing to a novel long-term strategy in controlling fungal biofilms on denture and other related biomaterials.

PHB/PCL fibrous membranes modified with SiO2@TiO2-based core@shell composite nanoparticles for hydrophobic and antibacterial applications.

In order to prepare multifunctional fibrous membranes with hydrophobicity, antibacterial properties and UV resistance, we used silica and titanium dioxide for preparing SiO2@TiO2 nanoparticles (SiO2@TiO2 NPs) to create roughness on the fibrous membranes surfaces. The introduction of TiO2 was used for improving UV resistance. N-Halamine precursor and silane precursor were introduced to modify SiO2@TiO2 NPs to synthesize SiO2@TiO2-based core@shell composite nanoparticles. The hydrophobic antibacterial fibrous membranes were prepared by a dip-pad process of electrospun biodegradable polyhydroxybutyrate/poly-ε-caprolactone (PHB/PCL) with the synthesized SiO2@TiO2-based core@shell composite nanoparticles. TEM, SEM and FT-IR were used to characterize the synthesized SiO2@TiO2-based core@shell composite nanoparticles and the hydrophobic antibacterial fibrous membranes. The fibrous membranes not only showed excellent hydrophobicity with an average water contact angle of 144° ± 1°, but also appreciable air permeability. The chlorinated fibrous membranes could inactivate all S. aureus and E. coli O157:H7 after 5 min and 60 min of contact, respectively. In addition, the chlorinated fibrous membranes exhibited outstanding cell compatibility with 102.1% of cell viability. Therefore, the prepared hydrophobic antibacterial degradable fibrous membranes may have great potential application for packaging materials.