Enhancing lignin dissolution and extraction: the effect of surfactants

The dissolution and extraction of lignin from biomass represents a great challenge due to the complex structure of this natural phenolic biopolymer. In this work, several surfactants (i.e., non-ionic, anionic, and cationic) were used as additives to enhance the dissolution efficiency of model lignin (kraft) and to boost lignin extraction from pine sawdust residues. To the best of our knowledge, cationic surfactants have never been systematically used for lignin dissolution. It was found that ca. 20 wt.% of kraft lignin is completely solubilized using 1 mol L-1 octyltrimethylammonium bromide aqueous solution. A remarkable dissolution efficiency was also obtained using 0.5 mol L-1 polysorbate 20. Furthermore, all surfactants used increased the lignin extraction with formic acid, even at low concentrations, such as 0.01 and 0.1 mol L-1. Higher concentrations of cationic surfactants improve the extraction yield but the purity of extracted lignin decreases.FCT: UID/QUI/00313/2020, PTDC/AGR-TEC/4814/2014, PTDC/ASP-SIL/30619/2017, UIDB/05183/2020, CEECIND/01014/2018, SFRH/BD/132835/2017, COMPETEinfo:eu-repo/semantics/publishedVersio

Antimicrobial performance of lignin embedded in bacterial nanocellulose membranes

The development of bio-based antimicrobial polymeric composites has never been so urgent. Novel antimi- crobial fibrous-based biocomposites will certainly allow the development of important solutions to fight the present and future Pandemics, while reducing the dependence of petrochemical based polymers and fibers. Lignin has a pivotal function in preventing the invasion of phytopathogens, thus, this work explores the anti- microbial potential of lignin when embedded in a biosynthesized fibrous nanomatrix with superior mechanical properties: bacterial nanocellulose (BNC). Lignin was subjected to alkali treatment to promote the inclusion of lignin within BNC which comprises pores ranging from 20 to 300 nm. Both alkali treatment efficiency, bac- tericidal and antiviral activities were investigatedThe authors would like to acknowledge the project PLASMAMED - PTDC/CTM-TEX/28295/2017 fnanced by FCT, FEDER and POCI in the frame of the Portugal 2020 program, the project UID/CTM/00264/2019 of 2C2T under the COMPETE and FCT/MCTES (PIDDAC) co-fnanced by FEDER through the PT2020 program. Liliana Melro acknowledges her Doctoral grant awarded by FCT (2020.04919.BD)

Bio-synthesised fibrous-based meshes for abdominal hernia with enhanced mechanical and antimicrobial properties

Abdominal hernia (AH) encompasses the most prevalent types of hernia: inguinal, umbilical and incisional. Notwithstanding current hernia complications represent a low death toll (nearly 0.001 % in developed countries), non-reducible hernias are the most severe cases, which require urgent surgical intervention due to their life-threatening nature. In a single year, at the United States of America, more than 800 thousand surgeries are performed to repair inguinal hernias. Abdominal hernia ubiquitous symptoms include pain, which may represent a mild discomfort or even an impairing morbidity. Nevertheless, some patients suffer from morbidity in the post-operative period. Recurrence was reduced when the application of a propylene mesh replaced primary suture repair more than 60 years ago. Surprisingly, currently the most prevalent hernia mesh materials are based on petrochemical plastics such as polypropylene, polyester, polystyrene and expanded polytetrafluoroethylene. Unfortunately, despite the plethora of commercial hernia meshes, an improvement of the hernia meshes is still warranted, since petrochemical materials exhibit a deterioration over time which generate complications and recurrence. This project envisages the complete replacement of the conventional plastic-based material of hernia meshes by a fully bio- based material with superior mechanical properties: bacterial nanocellulose (BNC). BNC is synthesized by bacteria and is composed of a 3D matrix of 100 % nanofibrils of cellulose, each with a diameter ranging between 20 to 100 nm. When BNC producing bacterium are cultured in static culture, the BNC is formed as membrane (nanoporous mesh comprising pores of 100 to 300 nm in diameter) at the surface of the culture medium and adopts the shape of the available surface. Therefore, it is easy to control the membrane surface shape, as well as its thickness, which can be controlled by the incubation time (longer incubation time will result in a larger thickness). The selection of the most adequate bacterium for the production of the hernia mesh will be performed Nevertheless, for a hernia mesh to be viable it requires pores with a specific diameter to allow the permeability of leukocytes, fibroblasts, and permit the arrangement of collagen and blood vessels. Per se, the BNC mesh does not possess such large specific pores with the required diameter (> 75 μm), thus it is proposed the design and development of a template to achieve a AH mesh that meets the necessary requirements. Furthermore, due to the high complexity of hernia mesh infection, which is extremely difficult to adequately treat without removing the mesh, this project envisages the functionalization of BNC AH mesh with antimicrobial properties. Two approaches will be considered for the BNC AH mesh functionalization, namely: in situ synthesis and adsorption through filtration. NPs optimal concentration and functionalization process will be examined and tailored to obtain a BNC AH mesh with effective antimicrobial activity and negligible cytotoxicity. According the AH implantation site, three different hernia meshes classes are usually applied: low, medium and high weight, thus the optimal antimicrobial BNC meshes of each class will be patented to represent a viable commercial alternative, by displaying superior mechanical properties, biocompatibility and low infection propensity, to considerably improve AH patience overall wellbeing.FEDER funds under the COMPETE program and by National Funds through Fundação para a Ciência e Tecnologia (FCT) under the project POCI-01- 0145-FEDER-007136 and UID/CTM/00264/2013. PLASMAMED project PTDC/CTMTEX/28295/2017 funded by FCT, FEDER e POCI through the program Portugal 202

Antimicrobial activity of bacterial nanocellulose modified with chestnut extract

Chestnut wood extracts are rich in tannins that exhibit numerous health-promoting properties. The incorporation of 5% (w/v) chestnut extract within the nanofibrous structure of bacterial nanocellulose (BNC) produced by Gluconacetobacter hansenii ATCC 53582 was obtained through exhaustion. This simple processing methodology resulted in a flexible (upon addition of 2% (w/v) glycerol), biodegradable, biocompatible nanocomposite for potential application in medical appliances.Portuguese Foundation for Science and Technology (FCT), FEDER funds through Portugal 2020 Competitive Factors Operational Program (POCI), and thePortuguese Government (PG) for the projects: UID/CTM/00264/2021 of Centre for Textil e Science and Technology (2C2T) and PTDC/CTM-TEX/1213/2020;FCT, the Ministry of Science, Technology and Higher Education (MCTES), the European Social Fund (FSE) and the European Union (UE)for her Ph.D. funding via scholarship 2020.04919.BD;FCT, FEDER, POCI, and PG for her research grant POCI-01-0247-ERDF-047124

Antimicrobial activity of a bacterial nanocellulose film functionalized with nisin Z for prospective burn wounds treatment

Supplementary Materials: The following are available online at https://www.mdpi.com/article/10 .3390/eca2022-12708/s1Burn wounds can lead to numerous severe complications including bacterial infections causing patient morbidity and mortality, mostly in low- and middle-income countries. The considerable increase in microbial resistance against traditional antibiotics is leading towards alternative strategies to treat bacterial infections. Nisin Z is an antimicrobial peptide which exhibits a significant antibacterial activity against Gram-positive bacteria. Its efficacy against Gram-negative bacteria is limited, nonetheless it can be improved with the addition of surfactants, such as ethylenediaminetetraacetic acid (EDTA). The incorporation of peptide and other biomolecules within a biopolymer matrix provides protection maintaining their antimicrobial potential. Bacterial nanocellulose (BNC) has been widely used as wound dressings. Its impressive water retention capacity (>99%) and porosity are beneficial to manage wounds due to its potential to absorb exudates, providing a breathable and humid environment. In this work, the functionalization of BNC with Nisin Z (BNC-NZ) via vacuum filtration is reported. The entrapment of the peptide inside the BNC films was confirmed through morphological characterization using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometry. Typical absorbance peaks of Nisin Z are easily identifiable at 1647 cm−1 (amide group) and 1520 cm−1 (bending of primary amines). Thermal gravimetric analysis (TGA) suggested that Nisin Z did not interfere with the BNC matrix. The antimicrobial activity of Nisin Z against five of the most common bacteria found in burn wounds was verified by minimum bactericidal concentration (MBC) ranging 8.0–256.0 µg/mL. Agar diffusion and shake flask methods revealed the potential of BNC-NZ for prospective applications in burn wound dressings.This research was funded by FEDER funds through COMPETE and by national funds through FCT via the projects POCI-01-0145-FEDER-028074 and UID/CTM/00264/2020. L.M. and T.D.T. also acknowledge FCT for their Ph.D. scholarships with references 2020.04919.BD and 2020.06046.BD.info:eu-repo/semantics/publishedVersio

Antibacterial properties of bacterial nanocellulose functionalized with metal nanoparticles via in situ synthesis

[Excerpt] Wound infections are generally caused by pathogens and multidrug-resistant (MDR) strains that render the administration of antibiotics ineffective. An alternative is to treat infected wounds at the initial stage using a fibrous bionanopolymer, bacterial nanocellulose (BNC), functionalized with antimicrobial metal nanoparticles (MNPs). BNC is a highly promising wound dressing due to its very high-water retention capacity (> 99 %) and high porosity. Such properties enable the absorbance of exudates, whilst maintaining the environment moist allowing the exchange of air. However, BNC is absent of antibacterial properties, thus gold (Au), copper (Cu), and copper oxide (Cu2O) NPs were incorporated within the nanofibrous structure of the biopolymer via in situ synthesis

Antiviral properties of flame retardant bacterial nanocellulose modified with mordenite

[Excerpt] Bacterial nanocellulose (BNC) is a 100 % cellulose nano-nonwoven textile synthesized by bacteria, comprising impressive mechanical properties. Cellulosic materials require flame retardant finishing, thus to reduce flammability of BNC a zeolite mordenite (MOR) was incorporated in its nano structure, without any additives.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI) and the project UID/CTM/00264/2021 of Centre for Textile Science and Technology (2C2T). PTDC/CTM-TEX/28295/2017, PTDC/CTM-TEX/1213/2020, and ARCHKNIT POCI-01-0247- FEDER-039733, funded by FCT, FEDER, COMPETE, and MCTES. Liliana Melro and Rui D. V. Fernandes acknowledge their PhD grants 2020.04919.BD and SFRH/BD/145269/2019

Bacterial nanocellulose films loaded with nisin Z -antibacterial efficacy against Staphylococcus aureus strains

Burn wounds can lead to numerous severe complications including bacterial infections causing patient morbidity and mortality, mostly in low- and middle-income countries. The Grampositive bacteria Staphylococcus aureus is one of the major causes of nosocomial infections in burn patients. Furthermore, the considerable increase of the microbial resistance against traditional antibiotics is leading towards alternative strategies to treat bacterial infections. Nisin Z is an antimicrobial peptide which exhibits a significant antibacterial activity against Gram-positive bacteria. The incorporation of peptide and other biomolecules within a biopolymer matrix provides protection maintaining their antimicrobial potential. Bacterial nanocellulose (BNC) has been widely used as wound dressings. Its impressive water retention capacity (>99%) and porosity are beneficial to manage wounds due to its potential to absorb exudates, providing a breathable and humid environment. In this work, the functionalization of BNC with nisin Z (BNC-NZ) via vacuum filtration is reported. The entrapment of the peptide inside the BNC films was confirmed through morphological characterization using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectrometry. Typical absorbance peaks of nisin Z are easily identifiable at 1647 cm−1 (amide group) and 1520 cm-1 (bending of primary amines). Thermal Gravimetric Analysis (TGA) suggested that nisin Z did not interfere with the BNC matrix. The antimicrobial activity of nisin Z against S. aureus strains including a multiple drug-resistant, was verified by Minimum Bactericidal Concentration (MBC). Agar Diffusion and Shake Flask methods revealed the potential of BNC-NZ for prospective applications in burn wound dressings

Antiviral properties of flame retardant bacterial nanocellulose modified with mordenite

Current COVID-19 pandemic has underscored the requirement of antiviral properties in a plethora of textile applications. These include textiles used in home areas prone to fire such as kitchens, windows and electronic panel areas, but also in the automotive industry such interior textiles and hood insulation pad covers. Therefore, this work describes the characterization of a fully sustainable textile: bacterial nanocellulose, functionalized to achieve an impressive flame retardancy