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A hybrid poly(N-isopropylacrylamide) (PNIPAm)/cellulose nanofibrils (CNFs) hydrogel composite was fabricated by inverted stereolithography 3D printing to provide a new platform for regulating lower critical solution temperature (LCST) properties and thus tuning optical and bioadhesive properties. The phenomena of interest in the as-printed PNIPAm/CNF hydrogels may be attributed to the fiber-reinforced composite system between crosslinked PNIPAm and CNFs. The optical tunability was found to be correlated to the micro/nano structures of the PNIPAm/CNF hydrogel films. It was found that PNIPAm/CNF hydrogels exhibit switchable bioadhesivity to bacteria in response to CNF distribution in the hydrogels. After 2.0 wt% CNF was incorporated, it was found that a remarkable 8°C reduction of the LCST was achieved relative to PNIPAm hydrogel crosslinked by TEGDMA without CNF. The prepared PNIPAm/CNF hydrogels possessed highly reversible optical, bioadhesion, and thermal performance, making them suitable to be used as durable temperature-sensitive sensors and functional biomedical devices., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

A heightened need to control the spread of infectious diseases prompted the current work in which functionalized and innovative antimicrobial tissue paper was developed with a hydrophobic spray-coating of chitosan (Ch) and cellulose nanocrystals (CNCs) composite. It was hypothesized that the hydrophobic nature of chitosan could be counterbalanced by the addition of CNC to maintain fiber formation and water absorbency. Light-weight tissue handsheets were prepared, spray-coated with Ch, CNC, and their composite coating (ChCNC), and tested for antimicrobial activity against Gram-negative bacteria Escherichia coli and a microbial sample from a human hand after using the rest room. Water absorption and strength properties were also analyzed. To activate the surface of cationized tissue paper, an oxygen/helium gas atmospheric plasma treatment was employed on the best performing antimicrobial tissue papers. The highest bactericidal activity was observed with ChCNC-coated tissue paper, inhibiting up to 98% microbial growth. Plasma treatment further improved the antimicrobial activity of the coatings. Water absorption properties were reduced with Ch but increased with CNC. This "self-disinfecting" bactericidal tissue has the potential to be one of the most innovative products for the hygiene industry because it can dry, clean, and resist the infection of surfaces simultaneously, providing significant societal benefits.

Antimicrobial activity is one of the most well-studied properties of hemp, with numerous contradictions and anecdotal information. However, most of the studies on antimicrobial activity of hemp have been focused on extractives, obtained by use of polar or nonpolar solvents such as petroleum ether, acetone, methanol, and ethanol, etc. This work compared the antimicrobial activity of unprocessed hemp hurds powder, processed hemp hurds-lignin containing nano-fibrillated cellulose (LNFC), and their ethanol extractives. The hemp hurd shives were pulped (defibrillated) to obtain fibers by employing a hydrothermal, carbonate and kraft pulping process. The obtained cellulose fibers were further processed into LNFC using intensive mechanical processing. LNFC films were prepared using a solvent casting method. The extractives of hemp hurd powder and differently treated pulps were obtained using ethanol and benzene. The obtained extractives were used to treat selected sterilized paper discs and hydrothermal pulped LNFC films. Extractives from the hemp hurds were characterized for the presence of antimicrobial active compounds using GC–MS. The LNFC films and extractives-treated paper substrate were tested against E. coli for their antimicrobial activity. The extractives-treated paper showed a significant reduction in bacterial growth and resulted in a zone of bacterial inhibition up to 1.85 mm in disk diffusion assays. The antimicrobial activity of extractives was confirmed by doing a colony-forming assay, which showed a bacterial inhibition by 98% colony forming units (CFU). However, no significant antimicrobial activity of unprocessed hemp hurd powder or LNFC films was observed. On the contrary, treating LNFC films with obtained extractives led to a reduction of CFU by 99.7%. These results of using hemp extractives and LNFC as antimicrobial coatings creates great potential for valorizing the industrial hemp residues for sustainable antimicrobial applications. [ABSTRACT FROM AUTHOR]

This review article was prompted by a remarkable growth in the number of scientific publications dealing with the use of nanocellulose (especially nanofibrillated cellulose (NFC), cellulose nanocrystals (CNC), and bacterial cellulose (BC)) to enhance the barrier properties and other performance attributes of new generations of packaging products. Recent research has confirmed and extended what is known about oxygen barrier and water vapor transmission performance, strength properties, and the susceptibility of nanocellulose-based films and coatings to the presence of humidity or moisture. Recent research also points to various promising strategies to prepare ecologically-friendly packaging materials, taking advantage of nanocellulose-based layers, to compete in an arena that has long been dominated by synthetic plastics. Some promising approaches entail usage of multiple layers of different materials or additives such as waxes, high-aspect ratio nano-clays, and surface-active compounds in addition to the nanocellulose material. While various high-end applications may be achieved by chemical derivatization or grafting of the nanocellulose, the current trends in research suggest that high-volume implementation will likely incorporate water-based formulations, which may include water-based dispersions or emulsions, depending on the enduses. [ABSTRACT FROM AUTHOR]