A significant antibiofilm and antimicrobial activity of chitosan-polyacrylic acid nanoparticles against pathogenic bacteria

Chitosan is known to exert antimicrobial activity without the need for any chemical modification; however, new derivatives of chitosan can be created to target multi-drug resistant bacteria. In this study, chitosan (CS) was cross-linked with sodium tripolyphosphate to form nanoparticles, which were then coated with polyacrylic acid (PAA). The SEM images revealed that the CS-PAA nanoparticles had spherical shapes with smooth surfaces and the size of the dried nanoparticles was approximately 222 nm. Biofilm formation was significantly inhibited by 0.5 mg/mL of CS-PAA. In-situ optical microscopy showed that CS-PAA nanoparticles inhibited the bacterial biofilm formation in Campylobacter jejuni, Pseudomonas aeruginosa, and Escherichia coli after a single treatment with 40 μg. Additionally, 20 µg of CS-PAA nanoparticles demonstrated antibacterial activity against the growth of C. jejuni, P. aeruginosa, and E. coli with notable inhibitory zones of 9, 12, and 13 mm, respectively (P < 0.01). The development of a novel and ecofriendly method for the preparation of chitosan nanoparticles through an interaction of chitosan with PAA shows promise tool to combat bacterial infections and validates effective antibacterial and antibiofilm properties against antibiotic resistant pathogens.

Novel poly (N-methacryloyl-L-alanine acid) grafted chitosan microspheres based solid-phase extraction coupled with ICP-MS for simultaneous detection of trace metal elements in food

Poly (N-methacryloyl-L-alanine acid) grafted tartaric acid-crosslinked chitosan microspheres (PNMA-TACS) were successfully synthesized and employed as a novel adsorbent for the separation and enrichment of metal ions in the food system. PNMA-TACS microspheres-based solid phase extraction (SPE) was coupled with ICP-MS for accurate quantification of trace V(V), Cr(III), As(III), Pb(II), Cd(II) and Cu(II). The obtained PNMA-TACS microspheres were characterized, and parameters influencing the method were optimized. Under optimal conditions, the calibration curves for Cu(II) and V(V) were linear within 0.01-30 μg L-1, the linear ranges of Cr(III), As(III), Pb(II) and Cd(II) were 0.01-15 μg L-1, and the detection limit of the developed approach was 1.1-3.7 ng L-1. The results were consistent with the consensus values of method validation implemented by two standards. Moreover, standard addition recovery experiments were performed in rice and milk powder, which achieved satisfactory recovery of 86.1-103.5%.

Microfluidic-based functional materials: new prospects for wound healing and beyond

Microfluidics has been applied to fabricate high-performance functional materials contributing to all physiological stages of wound healing. The advances of microfluidic-based functional materials for wound healing have been summarized.

Immobilization of recombinant Escherichia coli cells expressing glucose isomerase using modified diatomite as a carrier for effective production of high fructose corn syrup in packed bed reactor

To improve the operational stability of glucose isomerase in E. coli TEGI-W139F/V186T, the immobilized cells were prepared with modified diatomite as a carrier and 74.1% activity of free cells was recovered after immobilization. Results showed that the immobilized cells still retained 86.2% of the initial transformational activity after intermittent reused 40 cycles and the yield of D-fructose reached above 42% yield at 60 °C. Moreover, the immobilized cells were employed in the continuous production of High Fructose Corn Syrup (HFCS) in a recirculating packed bed reactor for 603 h at a constant flow rate. It showed that the immobilized cells exhibited good operational stability and the yield of D-fructose retained above 42% within 603 h. The space-time yield of high fructose corn syrup reached 3.84 kg L^-1 day^-1. The investigation provided an efficient immobilization method for recombinant cells expressing glucose isomerase with higher stability, and the immobilized cells are a promising biocatalyst for HFCS production.

Recent advances in microfluidic-aided chitosan-based multifunctional materials for biomedical applications

Chitosan-based biomaterials has shown great advantages in a broad range of applications, including drug delivery, clinical diagnosis, cell culture and tissue engineering. However, due to the lack of control over the fabrication processes by conventional techniques, the wide application of chitosan-based biomaterials has been hampered. Recently, microfluidics has been demonstrated as one of the most promising platforms to fabricate high-performance chitosan-based multifunctional materials with monodisperse size distribution and accurately controlled morphology and microstructures, which show great promising for biomedical applications. Here, we review recent progress of the fabrication of chitosan-based biomaterials with different structures and integrated functions by microfluidic technology. A comprehensive and in-depth depiction of critical microfluidic formation mechanism and process of various chitosan-based materials are first interpreted, with particular descriptions about the microfluidic-mediated control over the morphology and microstructures. Afterwards, recently emerging representative applications of chitosan-based multifunctional materials in various fields, are systematically summarized. Finally, the conclusions and perspectives on further advancing the microfluidic-aided chitosan-based multifunctional materials toward potential and versatile development for fundamental researches and biomedicine are proposed.

Monodisperse erythrocyte-sized and acid-soluble chitosan microspheres prepared via electrospraying

Monodisperse erythrocyte-sized and acid-soluble chitosan microspheres are successfully prepared by an electrospraying method with terephthalaldehyde as the cross-linker.