Search

The authors would like to acknowledge the Academy of Finland funding; No. 327248 (ValueBiomat) and 327865 (Bioeconomy). This work was a part of the Academy of Finland's Flagship Programme under Projects No. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES). The authors would also like to thank the Biohybrid Materials Research Group (Aalto University) for providing the HepG2 cells. The current study provides a comprehensive rheology study and a survey on direct ink writing of xanthan gum/cellulose nanocrystal (XG/CNC) bio-inks for developing 3D geometries that mimic soft tissue engineering scaffolds' physical and mechanical properties. The presence of CNC was found to be a critical prerequisite for the printability of XG bio-inks; accordingly, the hybrid XG/CNC bio-inks revealed the excellent viscoelastic properties that enabled precise control of hydrogel shaping and printing of lattice structures composed of up to eleven layers with high fidelity and fair resolution without any deformation after printing. The lyophilized 3D scaffolds presented a porous structure with open and interconnected pores and a porosity higher than 70%, vital features for tissue engineering scaffolds. Moreover, they showed a relatively high swelling of approximately 11 g/g, facilitating oxygen and nutrient exchange. Furthermore, the elastic and compressive moduli of the scaffolds that enhanced significantly upon increasing CNC content were in the range of a few kPa, similar to soft tissues. Finally, no significant cell cytotoxicity was observed against human liver cancer cells (HepG2), highlighting the potential of these developed 3D printed scaffolds for soft tissue engineering applications.

Antibiotic resistance development in bacteria is a serious threat to human health all over the world. One of the common ways of transmission of bacteria is contact with contaminated surfaces. Antimicrobial surfaces are promising solution for containment of spread of infection. Use of bio- based and biodegradable materials for antimicrobial coatings of disposable products are of great interest due to their lower environmental impact in comparison with synthetic compounds. In this study filter paper samples were uniformly coated with different amounts of softwood Kraft lignin nanoparticles using spraying or immersion methods. Presence of the particles on the samples’ surfaces were confirmed by Scanning Electron microscopy (SEM). Surface density of the particles on the surface were determined by weighing and by X-ray Photoelectron Spectroscopy (XPS). The Minimum Inhibitory Concentration (MIC) of LNPs dispersions for Staphylococcus aureus was 0.16 wt.-% in 24h contact time. The LNPs’ coatings demonstrated antimicrobial properties against methicillin-resistant Staphylococcus aureus (MRSA) which makes LNPs promising bio- based antimicrobial agent for development of antimicrobial surfaces.

The authors would like to acknowledge the Academy of Finland funding; No. 327248 (ValueBiomat) and 327865 (Bioeconomy). This work was a part of the Academy of Finland's Flagship Programme under Projects No. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES). The authors would also like to thank Ms. Marja Kärkkäinen for providing TEMPO-CNF and the Biohybrid Materials Research Group (Aalto University) for providing the HepG2 cells. Plant-based hydrogels have attracted great attention in biomedical fields since they are biocompatible and based on natural, sustainable, cost-effective, and widely accessible sources. Here, we introduced new viscoelastic bio-inks composed of quince seed mucilage and cellulose nanofibrils (QSM/CNF) easily extruded into 3D lattice structures through direct ink writing in ambient conditions. The QSM/CNF inks enabled precise control on printing fidelity where CNF endowed objects with shape stability after freeze-drying and with suitable porosity, water uptake capacity, and mechanical strength. The compressive and elastic moduli of samples produced at the highest CNF content were both increased by ~100% (from 5.1 ± 0.2 kPa and 32 ± 1 kPa to 10.7 ± 0.5 and 64 ± 2 kPa, respectively). These values ideally matched those reported for soft tissues; accordingly, the cell compatibility of the printed samples was evaluated against HepG2 cells (human liver cancer). The results confirmed the 3D hydrogels as being non-cytotoxic and suitable to support attachment, survival, and proliferation of the cells. All in all, the newly developed inks allowed sustainable 3D bio-hydrogels fitting the requirements as scaffolds for soft tissue engineering.

The increased awareness about environmental issues has resulted in developing novel materials and sustainable solutions to reduce the dependence on fossil-based products. Herein, cellulose from sisal was derivatized into carboxylic esters (acetate, Ac; butyrate, Bu; and hexanoate, Hx); the produced materials were “shaped” into mats composed of nano- and ultrathin fibers. Our objective was to assess the effects of cellulose ester degree of substitution (DS), low- and high DS, ca. 0.2 and 2.6; the length of the acyl group and the electrospinning flow rate, 45.5 and 65.5 μL/min on the morphology of the fibrous material obtained therefrom. Cellulose was converted into its carboxylic esters under homogeneous conditions using LiCl/N,N-dimethylacetamide solvent, and acid anhydrides as acylating agents. The obtained cellulose- acetate, Cel-Ac, butyrate, Cel-Bu, and hexanoate, Cel-Hx were dissolved in trifluoracetic acid. The solutions of esters were subjected to electrospinning, under positive voltage of 25 kV, and needle-collector distance of 4 cm. Scanning Electron Microscopy of the electrospun mats showed the formation of ultrathin- (100 nm > diameter

O presente estudo teve como uma das metas a esterificação da celulose de linter de algodão em meio homogêneo, usando como sistema de solvente N,N- dimetilacetamida/cloreto de lítio (DMAc/LiCl), e anidrido hexanóico ou cloreto de benzoíla como agentes esterificantes. A celulose de linter de algodão foi utilizada por ser uma fonte de rápido crescimento e considerada a celulose de maior pureza isolada de fontes vegetais. Na síntese de ésteres de celulose (hexanoato, benzoato, bem com ésteres mistos, hexanoato-benzoato de celulose) visou-se obter diferentes graus de substituição (GS = 1, 2 e 3) por meio do ajuste da razão Molag. esterificante/MolUAG. Os ésteres de celulose obtidos (caracterizados por FTIR, 1H RMN e TGA) foram utilizados como materiais de partida na preparação de mantas (mats) e esferas, o que correspondeu a uma segunda meta do estudo. As mantas de hexanoato de celulose foram obtidas por meio da técnica de eletrofiação a partir de soluções de N,N- dimetilacetamida/tetraidrofurano (DMAc/THF), e mantas de benzoato de celulose e hexanoato-benzoato foram preparadas a partir de soluções de ácido trifluoroacético (TFA). A eletrofiação resultou em redes de fibras ultrafinas (> 100 nm) em um amplo intervalo de diâmetro, por meio da variação das condições experimentais como taxa de fluxo (5,5, 15,5 e 45,5 μL.min-1), distância (5, 10, 15 e 25 cm), tensão (10, 15, 20 e 25 kV) e concentração (7, 9, 11, 13 e 15%). As micrografias(Microscopia Eletrônica de Varredura), indicaram que um menor fluxo de injeção favoreceu a formação de fibras ultrafinas de até 150 nm. As esferas foram obtidas por meio de gotejamento de uma solução de éster de celulose e acetona em contra solvente (água ou metanol). As esferas obtidas em água apresentaram diâmetros ligeiramente maiores e superfície menos rugosa, quando comparadas as esferas obtidas em metanol. Mantas e esferas de ésteres de celulose, selecionadas a partir dos resultados das respectivas caracterizações, foram utilizados como suporte para imobilização de lipases de Pseudomonas fluorescens (LPF) por encapsulamento, e posteriormente, aplicados na resolução cinética enzimática de cloridrinas racêmicas por meio de reação com acetato de vinila catalisada por lipase imobilizada, sendo esta etapa correspondente à terceira meta deste estudo. A resolução cinética foi analisada por Cromatógrafo a Gás acoplado a um detector de ionização de chama (CG-DIC) para a determinação dos parâmetros da reação. A lipase referência, não imobilizada, apresentou conversão moderada (c = 34%), excelente pureza enantiomérica (eep = 98%) e excelente razão enantiomérica (E = 212). Lipase imobilizada em mantas não apresentou atividade catalítica, provavelmente devido à tensão aplicada durante a eletrofiação, o que pode ter inativados as enzimas, e/ou devido à aplicação das mantas sobre suporte, o que pode ter prejudicado o acesso às enzimas. Para esferas de Hex 12 (15% LPF) obtidas usando água como contra solvente, os resultados se mostraram promissores, a conversão superior após 120h de reação (c = 40%) e pureza enantiomérica do produto 94%. Reutilizando as esferas em um segundo ciclo, observou-se uma redução de 24% da taxa de conversão de reação. A partir do conhecimento que se tem, este estudo pode ser considerado inédito, e pavimenta o caminho para aprofundamento de investigações sobre o assunto endereçado nele. The aim of the present study was the esterification of cotton linter cellulose in homogeneous medium, using as solvent system N, N-dimethylacetamide/lithium chloride (DMAc/LiCl), and hexanoic anhydride or benzoyl chloride as esterifying agents. Cotton linter cellulose was used because it is a fast-growing source and is considered the highest purity cellulose isolated from plant sources. The synthesis of cellulose esters (hexanoate, benzoate, as well as mixed esters, cellulose hexanoate- benzoate) aimed to obtain different degrees of substitution (GS = 1, 2 and 3) by adjusting the Molesterifying agent/ MolAGU ratio. The obtained cellulose esters (characterized by FTIR, 1H NMR, and TGA) were used as starting materials in the preparation of mats and spheres, which corresponded to a second goal of the study. Cellulose hexanoate mats were obtained by electrospinning technique from N,N- dimethylacetamide/tetrahydrofuran (DMAc/THF) solutions, and cellulose benzoate and hexanoate benzoate mats were prepared from trifluoroacetic acid (TFA) solutions. Electrospinning resulted in ultrathin fiber networks (> 100 nm) over a wide diameter range by varying the experimental conditions such as flow rate (5.5, 15.5 and 45.5 μL.min-1), distance (5, 10, 15 and 25 cm), voltage (10, 15, 20 and 25 kV) and concentration (7, 9, 11, 13 and 15%). SEM micrographs indicated that a smaller injection flow favored the formation of ultrathin fibers up to 150 nm. The spheres were prepared by dripping a solution of cellulose ester and acetone in counter solvent (water or methanol). The spheres obtained in water had slightly larger diameters and less rough surface when compared to spheres obtained in methanol. Mats and spheres of cellulose esters, selected from the results of the respective characterizations, were used as supports for immobilization of Pseudomonas fluorescens lipases (PFL) by encapsulation and subsequently applied to the enzymatic kinetic resolution of racemic hydrochlorins by reaction with vinyl acetate catalyzed by immobilized lipase, this step is the third goal of this study. The kinetic resolution was analyzed by Gas Chromatography coupled to a flame ionization detector (GC-FID) to determine the reaction parameters. The non-immobilized reference lipase showed moderate conversion (c = 34%), excellent enantiomeric purity (eep = 98%), and excellent enantiomeric ratio (E = 212). Lipase immobilized in mats did not show catalytic activity, probably due to the voltage applied during electroporation, which may have inactivated the enzymes, and/or the application of the blankets on support, which may have impaired enzyme access. For Hex 12 beads (15% LPF) obtained using water as a counter solvent, the results were promising, superior conversion after 120h reaction (c = 40%) and 94% enantiomeric purity. By reusing the spheres in a second cycle, a 24% reduction in the reaction conversion rate was observed. To our knowledge, this study is unprecedented and paves the way for further investigations on the subject addressed in it.&nbsp