Nanofibrillated cellulose originated from Rhododendron ponticum to produce scaffolds using 3D printing for biomedical applications.

Rhododendron ponticum is an invasive species that spreads rapidly and is described as one of the biggest threats to peatlands in Ireland. This study offers an innovative approach to utilizing Rhododendron waste. Initially, sawdust was submitted to a bleaching treatment and the nanofibrillated cellulose (NFC) was obtained using two different methods: ultra-fine friction grinding and twin-screw extrusion with the assistance of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) pre-treatment. The samples processed through twin-screw extrusion exhibited the presence of NFC at five intervals, as confirmed by TEM analysis. However, these samples displayed a higher diameter deviation compared to those processed through grinding alone. Notably, after 20 extrusion steps, the NFC diameter became more uniform, reaching approximately 35 nm. Sedimentation tests showed that extrusion produced more homogeneous cellulose size than the grinder method. However, FTIR characterization for the samples showed a unique band related to C-O-C glycosidic linkage. The results showed that grinding breaks these groups resulting in crystallinity values lower than extrusion, 50 % compared 60 %. Therefore, NFC with 20 steps by grinding was blended with polycaprolactone to produce a 3D scaffold using a 3D printer at different ratios of 1-5 % addition. The effect of 1 % of NFC was unique showing significant enhanced mechanical properties compared to pure polycaprolactone (PCL), additionally, the NFC does not exhibit toxicity so these materials show promise for biomedical applications.

Supraparticles as slow-release fertiliser in seedling potential growth of Eucalyptus urograndis and greenhouse gas flux impacts.

Slow-release urea fertilisers have been shown to present acceptable values for plant yield and mitigate the harmful effect of soil emission gases. This study synthesises a slow-release fertiliser containing fumed-nanosilica, nanofibrillated cellulose as well as sodium alginate as a urea carrier to analyse the growth parameters of Eucalyptus urograndis seedlings and potential emission of soil gases, N2O, CH4, CO2 and ammonia volatilisation. The developed supraparticles, arranged layered nanoparticle structure, presented a decrease in the normal nitrogen content of urea of 19%, which is attributed to the binding of this element. A good electrostatic interaction between the elements was confirmed by the FTIR with 20% of nitrogen content from its chemical composition and an increase in thermal degradation of the main components when synthesised. The profile of urea release presented to be as first-order with 85% of this compound was released only after 60 days. These characteristics led to statistically increased growth of Eucalyptus seedlings compared to the controls, which improves with higher dosages of urea. Values of biomass and characteristics of the plant were used for principal component analysis which resulted in good cluster formation based on the upward concentration of urea added to the plant. Nevertheless, flux gases were statistically higher for certain time periods on lower urea particle concentration, while increased concentration presented N2O emissions within standard rates with no significant variation in the other measured gases, which was attributed to the soil microbial targeted consumption. Therefore, this material can be beneficial in the agriculture industry.

The potential use of kraft lignins as natural ingredients for cosmetics: Evaluating their photoprotective activity and skin irritation potential.

The cosmetics market has recently undergone changes as consumers increasingly seek sustainable products. In this context, agro-derived lignins have the potential for cosmetics applications. Thus, this study investigated the photoprotective activity and skin irritation potential (OECD TG 439 with SkinVitro-RHE, an in-house reconstructed human epidermis (RHE) model) of a kraft lignin (LE) and two LE-derived lignins modified by enzymatic reactions to achieve higher molecular weight (Mw) (R1: intermediate Mw and E60: highest Mw). Results showed that LE and R1 lignins present adequate photoprotective activity with averages Sun Protection Factor (SPF) of 33.8 ± 0.02 and 22.7 ± 0.04, respectively. The E60 also present adequate SPF (22.4 ± 0.2); however, due to its poor solubility, this lignin has potential application as a physical filter. In terms of safety, these lignins did not cause skin irritation or cellular and structural damage to the epidermis. Additionally, using an analysis based on the autofluorescence feature of lignin, no sign of the tested lignins was found in exposed RHE models, indicating that these three lignins did not penetrate the skin. Altogether, the results indicate a promising application of kraft lignins for sunscreen products regarding safer alternatives and product sustainability. Also, the SkinVitro-RHE showed to be a good model for evaluating the skin irritation potential of substances, including natural cosmetic ingredients.

Characterization of Gels and Films Produced from Pinhão Seed Coat Nanocellulose as a Potential Use for Wound Healing Dressings and Screening of Its Compounds towards Antitumour Effects.

The reuse of agro-industrial waste assumes great importance today. Pinhão is the seed of Araucaria angustifolia, which is native to the mountains of southern Brazil, Paraguay, and Argentina. The coat is a by-product of this seed and is rich in phenolic compounds. The present study aimed to use the residue as a precursor material for the production of nanocellulose through the mechanical defibrillation process and perform the characterization of the films and the gel to investigate the effect on the physical and regenerative properties when incorporated with polyvinyl alcohol (PVA). The modulus of elasticity was higher when the MFC of pinhão was added to the PVA. Film and gel had their cytotoxicity tested by MTT assay using 3T3 fibroblast and Schwann cancer cells, and a migration assay was also performed using the scratch test on HaCat keratinocyte cells. For the scratch test, film and gel samples with low concentration presented a complete scratch closure in 72 h. Molecular docking was performed and quercetin had the ideal interaction score values, so it was used with the PACAP protein which presented a slightly moderate interaction with the protein synthesis of Schwann cells, presenting compactness of the compound after 14 ns.

Nanocellulose for peripheral nerve regeneration in rabbits using citric acid as crosslinker with chitosan and freeze/thawed PVA.

This work investigates peripheral nerve regeneration using membranes consisting of pure chitosan (CHI), which was further blended with nanofibrillated cellulose, with citric acid as crosslinker, with posterior addition of polyvinyl alcohol, with subsequent freeze thawing. Nanocellulose improves the mechanical and thermal resistance, as well as flexibility of the film, which is ideal for the surgical procedure. The hydrogel presented a slow rate of swelling, which is adequate for cell and drug delivery. A series ofin vitrotests revealed to be non-toxic for neuronal Schwann cell from the peripheral nervous system of Rattus norvegicus, while there was a slight increase in toxicity if crosslink is performed-freeze-thaw. Thein vivoresults, using rabbits with a 5 mm gap nerve defect, revealed that even though pure CHI was able to regenerate the nerve, it did not present functional recovery with only the deep pain attribute being regenerated. When autologous implant was used jointly with the biomaterial membrane, as a covering agent, it revealed a functional recovery within 15 d when cellulose and the hydrogel were introduced, which was attributed to the film charge interaction that may help influence the neuronal axons growth into correct locations. Thus, indicating that this system presents ideal regeneration as nerve conduits.

Microfibrillated cellulose films containing chitosan and tannic acid for wound healing applications.

The effectiveness of tannic acid as antimicrobial and wound healing for burns have been shown for a century; however, uncontrolled target dosage may result in undesirable side-effects. Remarkably, tannic acid polyphenols compounds crosslinked with polymeric materials produce a strong composite containing the beneficial properties of this tannin. However, investigation of the crosslink structure and its antibacterial and regenerative properties are still unknown when using nanocellulose by mechanical defibrillation; additionally, due to the potential crosslink structure with chitosan, its structure can be complex. Therefore, this work uses bleach kraft nanocellulose in order to investigate the effect on the physical and regenerative properties when incorporated with chitosan and tannic acid. This film results in increased rigidity with a lamellar structure when incorporated with tannic acid due to its strong hydrogen bonding. The release of tannic acid varied depending on the structure it was synthesised with, whereas with chitosan it presented good release model compared to pure cellulose. In addition, exhibiting similar thermal stability as pure cellulose films with antibacterial properties tested against S. aureus and E. coli with good metabolic cellular viability while also inhibiting NF-κB activity, a characteristic of tannic acid.

Antioxidant, antibacterial and antitumoural activities of kraft lignin from hardwood fractionated by acid precipitation.

Kraft lignin, so far useful for energy generation, has been gathering considerable attention as an alternative material to replace fossil-based resources mainly due to its high phenolic content. However, the wide molecular weight distribution and chemical composition heterogeneity led to the development of fractionation methods. Herein, to narrow such characteristics we used eucalypt kraft lignin fractionated at pH's 9, 7, 5 and 3 by sequential acid precipitation. These lignin fractions were first characterised by simultaneous pyrolysis and trimethylsilylation (SPyT) with N-Methyl-N-(trimethylsilyl) trifluoroacetamide with posterior tests of antioxidant, antibacterial, and antitumour activities. We observed higher ratio of syringyl/guaiacyl groups and increase in antioxidant activity in those fractions with lower molecular weight (precipitated at lower pH's). Fractions precipitated at pH's 9 and 7 have shown an outstanding antibacterial activity against five bacteria. Moreover, fractions 7 and 5 presented at cytotoxicity tests higher ability to inhibit the growth of U87MG and T98G glioma cells, while only a slight inhibition of adult human fibroblasts (non-tumour cells) was detected.

Yerba Mate Extract in Microfibrillated Cellulose and Corn Starch Films as a Potential Wound Healing Bandage.

Microfibrillated cellulose films have been gathering considerable attention due to their high mechanical properties and cheap cost. Additionally, it is possible to include compounds within the fibrillated structure in order to confer desirable properties. Ilex paraguariensis A. St.-Hil, yerba mate leaf extract has been reported to possess a high quantity of caffeoylquinic acids that may be beneficial for other applications instead of its conventional use as a hot beverage. Therefore, we investigate the effect of blending yerba mate extract during and after defibrillation of Eucalyptus sp. bleached kraft paper by ultrafine grinding. Blending the extract during defibrillation increased the mechanical and thermal properties, besides being able to use the whole extract. Afterwards, this material was also investigated with high content loadings of starch and glycerine. The results present that yerba mate extract increases film resistance, and the defibrillated cellulose is able to protect the bioactive compounds from the extract. Additionally, the films present antibacterial activity against two known pathogens S. aureus and E. coli, with high antioxidant activity and increased cell proliferation. This was attributed to the bioactive compounds that presented faster in vitro wound healing, suggesting that microfibrillated cellulose (MFC) films containing extract of yerba mate can be a potential alternative as wound healing bandages.

Thermal and chemical characterization of Dicksonia sellowiana extract by means of thermal analysis

Abstract Dicksonia sellowiana Hook., Dicksoniaceae, is a tree-fern which is being recently used in medicine mainly for its phytotherapic activities. While several other studies have focused on D. sellowiana extract characterization in terms of its biological and antioxidant activity, the novelty of this work aims to understand the fate of this extract during thermal disposal through thermogravimetry/differential thermal analysis, thermogravimetry/mass spectrometry, Fourier transform infrared spectroscopy and elemental analysis, to further characterize this plant's extract. Thermal analysis revealed mass loss within three well-defined steps, with the respective mass signals represented generated during heating. Light-volatiles were released during the first step, with release of NO2, CO2, and ethanol in the following, as a result of extract pyrolytic decomposition. Furthermore, mass signals variation during heating indicated the release of harmless by products in contrast to other pharmaceutical and personal care products. Finally, chemical characterization confirmed the observed under thermal analysis suggesting a highly polar structure within extract's composition.

Green Formation of Robust Supraparticles for Cargo Protection and Hazards Control in Natural Environments.

In parallel with important technological advances, nanoparticles have brought numerous environmental and toxicological challenges due to their high mobility and nonspecific surface activity. The hazards associated with nanoparticles can be significantly reduced while simultaneously keeping their inherent benefits by superstructuring. In this study, a low-temperature and versatile methodology is employed to structure nanoparticles into controlled morphologies from biogenic silica, used as a main building block, together with cellulose nanofibrils, which promote cohesion. The resultant superstructures are evaluated for cargo loading/unloading of a model, green biomolecule (thymol), and for photo-accessibility and mobility in soil. The bio-based superstructures resist extremely high mechanical loading without catastrophic failure, even after severe chemical and heat treatments. Additionally, the process allows pre and in situ loading, and reutilization, achieving remarkable dynamic payloads as high as 90 mg g-1 . The proposed new and facile methodology is expected to offer a wide range of opportunities for the application of superstructures in sensitive and natural environments.

Controlled biocide release from hierarchically-structured biogenic silica: surface chemistry to tune release rate and responsiveness.

Biocides are essential for crop protection, packaging and several other biosystem applications. Therein, properties such as tailored and controlled release are paramount in the development of sustainable biocide delivery systems. We explore the self-similar nano-organized architecture of biogenic silica particles to achieve high biocide payload. The high surface area accessibility of the carrier allowed us to develop an efficient, low energy loading strategy, reaching significant dynamic loadings of up to 100 mg·g-1. The release rate and responsiveness were tuned by manipulating the interfaces, using either the native hydroxyl surfaces of the carrier or systems modified with amines or carboxylic acids in high density. We thoroughly evaluated the impact of the carrier-biocide interactions on the release rate as a function of pH, ionic strength and temperature. The amine and carboxyl functionalization strategy led to three-fold decrease in the release rate, while higher responsiveness against important agro-industrial variables. Key to our discoveries, nanostructuring thymol in the biogenic silica endowed systems with controlled, responsive release promoting remarkable, high and localized biocidal activity. The interfacial factors affecting related delivery were elucidated for an increased and localized biocidal activity, bringing a new light for the development of controlled release systems from porous materials.

Controlled release for crop and wood protection: Recent progress toward sustainable and safe nanostructured biocidal systems.

We review biocide delivery systems (BDS), which are designed to deter or control harmful organisms that damage agricultural crops, forests and forest products. This is a timely topic, given the growing socio-economical concerns that have motivated major developments in sustainable BDS. Associated designs aim at improving or replacing traditional systems, which often consist of biocides with extreme behavior as far as their solubility in water. This includes those that compromise or pollute soil and water (highly soluble or volatile biocides) or those that present low bioavailability (poorly soluble biocides). Major breakthroughs are sought to mitigate or eliminate consequential environmental and health impacts in agriculture and silviculture. Here, we consider the most important BDS vehicles or carriers, their synthesis, the environmental impact of their constituents and interactions with the active components together with the factors that affect their rates of release such as environmental factors and interaction of BDS with the crops or forest products. We put in perspective the state-of-the-art nanostructured carriers for controlled release, which need to address many of the challenges that exist in the application of BDS.

Assessment of Nano Cellulose from Peach Palm Residue as Potential Food Additive: Part II: Preliminary Studies.

High consumption of dietary fibers in the diet is related to the reduction of the risk of non-transmitting of chronic diseases, prevention of the constipation etc. Rich diets in dietary fibers promote beneficial effects for the metabolism. Considering the above and recognizing the multifaceted advantages of nano materials, there have been many attempts in recent times to use the nano materials in the food sector including as food additive. However, whenever new product for human and animal consumption is developed, it has to be tested for their effectiveness regarding improvement in the health of consumers, safety aspects and side effects. However, before it is tried with human beings, normally such materials would be assessed through biological tests on a living organism to understand its effect on health condition of the consumer. Accordingly, based on the authors' finding reported in a previous paper, this paper presents body weight, biochemical (glucose, cholesterol and lipid profile in blood, analysis of feces) and histological tests carried out with biomass based cellulose nano fibrils prepared by the authors for its possible use as food additive. Preliminary results of the study with mice have clearly brought out potential of these fibers for the said purpose.