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The use of natural nanocomponents for increasing the mechanical strength of paper in the aerodynamic method has been investigated. Milled bacterial cellulose and a fine fraction of sulphate bleached softwood cellulose formed during grinding (secondary fines) were used as nanocomponents. The treatment with nanocomponents was carried out while moistening the fibrous layer with the use of an anti-adhesive material providing uniform one sided application of substances in the form of a suspension on the paper surface. The growth of the indicators of the mechanical strength of paper occurred due to the formation of additional hydrogen bonds and an increase in the interfacial interaction between the fibrous layer of plant cellulose and the nanocomponent. It was found that the use of a suspension of bacterial cellulose is more promising due to the low consumption of the binder with a significant increase in the mechanical strength of the paper. The application of a bacterial cellulose coating layer on aerodynamically molded eucalyptus cellulose makes it possible to increase the mechanical strength of the paper to consumer requirements with the consumption of bacterial cellulose in an amount of 0.9% to 1.5% by weight of absolutely dry eucalyptus cellulose., Исследовано применение природных нанокомпонентов для повышения механической прочности бумаги при аэродинамическом способе формования. В качестве нанокомпонентов использовали измельченную бактериальную целлюлозу и мелкую фракцию сульфатной беленой хвойной целлюлозы, образующуюся в процессе размола (вторичную мелочь). Введение нанокомпонентов проводили при увлажнении волокнистого слоя с применением антиадгезионного материала, обеспечивающего равномерное одностороннее нанесение веществ в виде суспензии на поверхность бумаги. Рост показателей механической прочности бумаги происходил за счет образования дополнительных водородных связей и возрастания межфазного взаимодействия между волокнистым слоем из растительной целлюлозы и нанокомпонентами. Установлено, что использование суспензии бактериальной целлюлозы более перспективно из-за малого расхода при значительном повышении показателей механической прочности бумаги. Нанесение покровного слоя бактериальной целлюлозы на бумагу аэродинамического формования из сульфатной беленой эвкалиптовой целлюлозы позволяет повысить значение механической прочности бумаги до потребительских требований при расходе бактериальной целлюлозы в количестве от 0.9 до 1.5% к массе абсолютно сухой целлюлозы.

The current work describes the development of a "nanopaper-based analytical device (NAD)", through the embedding of curcumin in transparent bacterial cellulose (BC) nanopaper, as a colorimetric assay kit for monitoring of iron and deferoxamine (DFO) as iron-chelating drug in biological fluids such as serum blood, urine and saliva. The iron sensing strategy using the developed assay kit is based on the decrease of the absorbance/color intensity of curcumin-embedded in BC nanopaper (CEBC) in the presence of Fe(III), due to the formation of Fe(III)-curcumin complex. On the other hand, releasing of Fe(III) from Fe(III)-CEBC upon addition of DFO as an iron-chelating drug, due to the high affinity of this drug to Fe(III) in competition with curcumin, which leads to recovery of the decreased absorption/color intensity of Fe(III)-CEBC, is utilized for selective colorimetric monitoring of this drug. The absorption/color changes of the fabricated assay kit as output signal can be monitored by smartphone camera or by using a spectrophotometer. The results of our developed sensor agreed well with the results from a clinical reference method for determination of Fe(III) concentration in human serum blood samples, which revealed the clinical applicability of our developed assay kit. Taken together, regarding the advantageous features of the developed sensor as an easy-to-use, non-toxic, disposable, cost-effective and portable assay kit, along with those of smartphone-based sensing, it is anticipated that this sensing bioplatform, which we name lab-on-nanopaper, will find utility for sensitive, selective and easy diagnosis of iron-related diseases (iron deficiency and iron overload) and therapeutic drug monitoring (TDM) of iron-chelating drugs in clinical analysis as well.

Due to the combined advantages of cellulose and nanoscale (diameter 20–60 nm), bacterial cellulose possesses a series of attractive features including its natural origin, moderate biosynthesis process, good biocompatibility, and cost-effectiveness. Moreover, bacterial cellulose nanofibers can be conveniently processed into three-dimensional (3D) intertwined structures and form stable paper devices after simple drying. These advantages make it suitable as the material for construction of organ-on-a-chip devices using matrix-assisted sacrificial 3D printing. We successfully fabricated various microchannel structures embedded in the bulk bacterial cellulose hydrogels and retained their integrity after the drying process. Interestingly, these paper-based devices containing hollow microchannels could be rehydrated and populated with relevant cells to form vascularized tissue models. As a proof-of-concept demonstration, we seeded human umbilical vein endothelial cells (HUVECs) into the microchannels to obtain the vasculature and inoculated the MCF-7 cells onto the surrounding matrix of the paper device to build a 3D paper-based vascularized breast tumor model. The results showed that the microchannels were perfusable, and both HUVECs and MCF-7 cells exhibited favorable proliferation behaviors. This study may provide a new strategy for constructing simple and low-cost in vitro tissue models, which may find potential applications in drug screening and personalized medicine.

Funding Information: KSK and AB acknowledge funding by the UK Engineering and Physical Sciences Research Council (EPSRC) (EP/K014676/1). KSK also acknowledges Academy of Finland (Project number 310943). EK is grateful for the support by the FinnCERES Materials Bioeconomy Ecosystem. Funding Information: Open access funding provided by Aalto University. KSK and AB acknowledge funding by the UK Engineering and Physical Sciences Research Council (EPSRC) (EP/K014676/1). KSK also acknowledges Academy of Finland (Project number 310943). Publisher Copyright: © 2021, The Author(s). Copyright: Copyright 2021 Elsevier B.V., All rights reserved. Cellulose nanopapers provide diverse, strong and lightweight templates prepared entirely from sustainable raw materials, cellulose nanofibers (CNFs). Yet the strength of CNFs has not been fully capitalized in the resulting nanopapers and the relative influence of CNF strength, their bonding, and biological origin to nanopaper strength are unknown. Here, we show that basic principles from paper physics can be applied to CNF nanopapers to illuminate those relationships. Importantly, it appeared that ~ 200 MPa was the theoretical maximum for nanopapers with random fibril orientation. Furthermore, we demonstrate the contrast in tensile strength for nanopapers prepared from bacterial cellulose (BC) and wood-based nanofibrillated cellulose (NFC). Endemic amorphous polysaccharides (hemicelluloses) in NFC act as matrix in NFC nanopapers, strengthening the bonding between CNFs just like it improves the bonding between CNFs in the primary cell wall of plants. The conclusions apply to all composites containing non-wovenfiber mats as reinforcement.

This paper addresses two key challenges toward an integrated forward error-correcting biosensor based on our previously reported self-assembled quick-response (QR) code. The first challenge involves the choice of the paper substrate for printing and self-assembling the QR code. We have compared four different substrates that includes regular printing paper, Whatman filter paper, nitrocellulose membrane and lab synthesized bacterial cellulose. We report that out of the four substrates bacterial cellulose outperforms the others in terms of probe (gold nanorods) and ink retention capability. The second challenge involves remote activation of the analyte sampling and the QR code self-assembly process. In this paper, we use light as a trigger signal and a graphite layer as a light-absorbing material. The resulting change in temperature due to infrared absorption leads to a temperature gradient that then exerts a diffusive force driving the analyte toward the regions of self-assembly. The working principle has been verified in this paper using assembled biosensor prototypes where we demonstrate higher sample flow rate due to light induced thermal gradients.

Luminescent quantum dot (QD) ink is currently a powerful tool for generating hidden information on paper substrates. Herein, we fabricated a nanohybrid ink of bacterial cellulose nanocrystal (BCNC) and UV-responsive ZnO QD via electrostatic self-assembly for improving solvent resistance and message encryption process. Under investigations on the printed areas, the nanohybrid can slightly infiltrate into the paper fibers and form a thin layer on the top of paper substrates, conferring an enhanced print permanence against wetting conditions while maintaining the daylight unobservability and its luminescent stability. The water resistance of the proposed nanohybrid ink enables developing a higher security level that the prints can be submerged in CuCl2 aqueous solutions to quench the luminescent message. The concealed message can eventually be revealed under UV light again after submerging in EDTA solution. Our ZnO QD/BCNC nanohybrid with eco-friendly nature therefore exhibits great potential as security marking ink for counterfeit protection with sustainable uses.

The main goal of this work was to reinforce softwood pulp (SP) with bacterial cellulose (BC) to generate a sustainable biocomposite. BC is a nanocellulose, which was anticipated to increase interfacial adhesion between the cellulosic fibers and BC. The organism used was Gluconacetobacter xylinus, which was incubated in a static Hestrin-Schramm culture at 28°C for 14days. The specimens of BC, SP and the reinforced SP with BC were characterized using X-ray diffraction (XRD), FT-IR, FESEM, and physico-mechanical testing. The crystallinity index was found to be 83 and 54% for BC and SP, respectively. FT-IR spectra showed that the composition of BC was fully different from that of SP fibers. Based on FESEM images, one can conclude that BC and softwood fibers do form a good combination with a nonporous structure. BC fibers fill in among the softwood fibers in the sheet. The physical and mechanical properties showed that as the dosage of BC increased, the properties of tensile index, tear index, and burst index greatly improved, while the porosity and the elongation decreased. The reason for the improved mechanical properties can be attributed to the increase of interfibrillar bonding which reduced porosity. This would be due to the high aspect ratio of BC that is capable of connecting between the cellulosic fibers and BC nanofibers, enhancing a large contact surface and therefore producing excellent coherence. This study suggests that BC could be a promising material for reinforcing composites at low loading.

Herein, we introduce a nanopaper-based analytical device (NAD) or “lab-on-nanopaper” device for visual sensing of human serum albumin (HSA) in human blood serums, which relies on embedding of curcumin within transparent bacterial cellulose (BC) nanopaper. BC nanopaper is an appropriate candidate to be an excellent platform for the development of optical (bio)sensors due to having exceptional properties such as optical transparency, high flexibility, porosity, biodegradability, and printability. The hydrophilic test zones were created on the fabricated bioplatform through creating the hydrophobic walls via laser printing technology. The color changes of curcumin embedded in BC nanopaper (CEBC) due to the inhibitory effect of HSA on the curcumin degradation in alkaline solutions, which can be monitored visually (naked eye/Smartphone camera) or spectroscopically using a spectrophotometer, were linearly proportional to the HSA concentration in the range of 10–300 μM and 25–400 μM, respectively. The developed NAD/CEBC as a novel albumin assay kit was successfully utilized to the determination of HSA in human blood serum samples with satisfactory results. Building upon the fascinating features of BC nanopaper as a very promising bioplatform in optical (bio)sensing applications we are confident “lab-on-nanopaper” devices/NADs, which take the advantages of the nanopaper and also meet the ASSURED criteria, could be considered as a new generation of optical (bio)sensing platforms that are currently based on paper, glass or plastic substrates.

Bacterial cellulose (BC) samples were obtained using two culture media (glucose and glucose+fructose) and two bacteria (Komagataeibacter rhaeticus and Komagataeibacter hansenii). Nanopaper was obtained from the BC through oxidation and both were studied to determine the impact of culture media and bacteria strain on nanofiber structure and mechanical properties. AFM and SEM were used to investigate fibre dimensions and network morphology; FTIR and XRD to determine cellulose purity and crystallinity; carboxyl content, degree of polymerisation and zeta potential were used to characterise nanofibers. Tensile testing showed that nanopaper has up to 24 times higher Young's modulus (7.39GPa) than BC (0.3GPa). BC displayed high water retention values (86-95%) and a degree of polymerisation up to 2540. Nanofibers obtained were 80-120nm wide and 600-1200nm long with up to 15% higher crystallinity than the original BC. It was concluded that BC is an excellent source for easily obtainable, highly crystalline and strong nanofibers.

Bacterial cellulose is a biological macromolecule synthesized by bacteria of high purity and crystallinity. Bacterial cellulose nanofibers (BCNF) have been produced by soft homogenization and added to a recycled pulp to improve its quality. The benefits of BCNF on mechanical, physical and optical paper properties have been quantified and the retention mechanism of the BCNF in the paper network has been proposed. The use of BC to improve paper strength is usually limited by the decrease of tear index. The novelty of this work is that these two effects are decoupled by the addition of BCNF of low fibrillation (35.2%). In this way, some BCNF clusters are produced together with the individual nanofibers. Thus, with the addition of 3% BCNF, tensile and tear indexes as well as strain at break were improved by 11.1, 7.6, and 66.8%, respectively. Furthermore, the clusters were retained in the fiber network not only by hydrogen bonding, but also by physical retention within the gaps. Therefore, the addition of BCNF not only increases the mechanical properties of paper but also makes the handsheets more flexible and facilitates filler retention.

Cellulose nanopapers have gained significant attention in recent years as large-scale reinforcement for high-loading cellulose nanocomposites, substrates for printed electronics and filter nanopapers for water treatment. The mechanical properties of nanopapers are of fundamental importance for all these applications. Cellulose nanopapers can simply be prepared by filtering a suspension of nanocellulose, followed by heat consolidation. It was already demonstrated that the mechanical properties of cellulose nanopapers can be tailored by the fineness of the fibrils used or by modifying nanocellulose fibrils for instance by polymer adsorption, but nanocellulose blends remain underexplored. In this work, we show that the mechanical and physical properties of cellulose nanopapers can be tuned by creating nanopapers from blends of various grades of nanocellulose, i.e. (mechanically refined) bacterial cellulose or cellulose nanofibrils extracted from never-dried bleached softwood pulp by chemical and mechanical pre-treatments. We found that nanopapers made from blends of two or three nanocellulose grades show synergistic effects resulting in improved stiffness, strength, ductility, toughness and physical properties. This article is part of a discussion meeting issue ‘New horizons for cellulose nanotechnology’.

Current conservation practice is to replace the water in cell structures of waterlogged wood with a synthetic polymer. Because cellulose is an integral component of wood, they are likely to show higher compatibility than synthetic polymers. Bacterial cellulose (BC) can be relatively easily grown from Acetobacter xylinum in liquid medium at 25°C–30°C using fructose as nutrition. The purpose of this original research was to determine the potential of growing cellulose directly onto waterlogged wood. Bonding between BC and paper substrates, used to model the cellulose component of wood, was strengthened by using autoclaved media and by optimising access to oxygen. Pre-treating paper with acetone increased bonding strength between BC and Munktell filter paper. Despite the presence of potentially competing bacteria, BC grew at surfaces and within the pores of heavily degraded waterlogged archaeological wood. Initial investigations into conserving waterlogged wood with BC show promise, but require further development.

Bacterial cellulose is an ideal material that is sustainable, biodegradable and inherently capable of functionalization. Hence this has been functionalized with a single component, Ni to exhibit multiple functionalities such as electrical conductivity, magnetic sensitivity as well as catalytic activity in both dried and hydrogel forms. A novel, simple ‘inverse chemical reduction’ technique has been developed to incorporate this component and make bacterial cellulose multifunctional. This technique mercerizes and opens the interfibrillar spaces which results in the formation of nanoparticles that lead to percolating paths for conduction. The flexible sheet becomes electrically conducting with just 20 vol% of nanoparticles in the composite as determined by thermogravimetry. The room temperature electrical conductance increases by about 7 orders of magnitude, 10−6–10 S on changing the Ni-precursor solution concentration from 0.015 to 0.02 M, indicating this to be the critical concentration for conduction percolation. The composites are highly magnetic at room temperature with a maximum energy product of 140 J m−3, comparable to some of the commercially available bonded oxide magnets. The hydrogel form of the nanocomposite is found to be catalytically active. The catalytic activity is retained even after leaving the nanocomposite hydrogel in water for 12 h in water.

Dental root canal treatment is required when dental caries progress to infection of the dental pulp. A major goal of this treatment is to provide complete decontamination of the dental root canal system. However, the morphology of dental root canal systems is complex, and many human dental roots have inaccessible areas. In addition, dental reinfection is fairly common. In conventional treatment, a cotton pellet and paper point made from plant cellulose is used to dry and sterilize the dental root canal. Such sterilization requires a treatment material with high absorbency to remove any residue, the ability to improve the efficacy of intracanal medication and high biocompatibility. Bacterial cellulose (BC) is produced by certain strains of bacteria. In this study, we developed BC in a pointed form and evaluated its applicability as a novel material for dental canal treatment with regard to solution absorption, expansion, tensile strength, drug release and biocompatibility. We found that BC has excellent material and biological characteristics compared with conventional materials, such as paper points (plant cellulose). BC showed noticeably higher absorption and expansion than paper points, and maintained a high tensile strength even when wet. The cumulative release of a model drug was significantly greater from BC than from paper points, and BC showed greater compatibility than paper points. Taken together, BC has great potential for use in dental root canal treatment.

5 páginas, 4 figuras, 1 tabla.-- et al., Nanostructured biological materials inspire the creation of materials with tunable mechanical properties. Strong cellulose nanofibrils derived from bacteria or wood, can form ductile or tough networks, that are suitable as functional materials. Here, we show that freeze-dried bacterial cellulose nanofibril aerogels can be used as templates for making lightweight porous magnetic aerogels, which can be compacted into a stiff magnetic nanopaper. The 20–70-nm-thick cellulose nanofibrils act as templates for the non-agglomerated growth of ferromagnetic cobalt ferrite nanoparticles (diameter, 40–120 nm). Unlike solvent-swollen gels and ferrogels our magnetic aerogel is dry, lightweight, porous (98%), flexible, and can be actuated by a small household magnet. Moreover, it can absorb water and release it upon compression. Owing to their flexibility, high porosity and surface area, these aerogels are expected to be useful in microfluidics devices and as electronic actuators., This work was supported by the Stiftelsen för Strategisk Forskning Center BIOMIME at KTH (Royal Institute of Technology), the Swedish Research Council, the Swedish Foundation for Strategic Research, the Wallenberg Wood Science Center, the Knut and Alice Wallenberg Foundation (Mikro/Nanovetenskap), the Swedish Defence Research Agency, the Spanish Ministerio de Ciencia e Innovación (MAT2007-66309-C02 and CSD2006-00012 Consolider-Ingenio 2010), the Catalan Direcció General de Recerca (2009-DGR-1292) and the Academy of Finland.

Herein, we introduce a new strategy for green, in-situ generation of silver nanoparticles using flexible and transparent bacterial cellulose nanopapers. In this method, adsorbed silver ions on bacterial cellulose nanopaper are reduced by the hydroxyl groups of cellulose nanofibers, acting as the reducing agent producing a bionanocomposite "embedded silver nanoparticles in transparent nanopaper" (ESNPs). The fabricated ESNPs were investigated and characterized by field emission scanning electron microscopy (FE-SEM), UV-visible spectroscopy (UV-vis), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and energy-dispersive X-ray spectroscopy (EDX). The important parameters affecting the ESNPs were optimized during the fabrication of specimens. The resulting ESNPs were used as a novel and sensitive probe for the optical sensing of cyanide ion (CN(-)) and 2-mercaptobenzothiazole (MBT) in water samples with satisfactory results. The change in surface plasmon resonance absorption intensity of ESNPs was linearly proportional to the concentration in the range of 0.2-2.5 µg mL(-1) and 2-110 µg mL(-1) with a detection limit of 0.012 µg mL(-1) and 1.37 µg mL(-1) for CN(-) and MBT, respectively.

Bacterial cellulose (BC) synthesized by Gluconacetobacter sucrofermentans CECT 7291 seems to be a good option for the restoration of degraded paper. In this work BC layers are cultivated and purified by two different methods an alkaline treatment when the culture media contains ethanol and a thermal treatment if the media is free from ethanol. The main goal of these tests was the characterization of BC layers measured in terms of tear and burst indexes, optical properties, SEM, X-ray diffraction, FTIR, degree of polymerization, static and dynamic contact angles, and mercury intrusion porosimetry. The BC layers were also evaluated in the same terms after an aging treatment. Results showed that BC has got high crystallinity index, low internal porosity, good mechanical properties and high stability over time, especially when purified by the alkaline treatment. These features make BC an adequate candidate for degraded paper reinforcement. © 2014 Elsevier Ltd.

Aim: The purpose of this work was to study the feasibility of producing economic flame retardant bacterial cellulose (BC) and evaluating its behaviour in paper production. Methods and Results: This type of BC was prepared by Gluconacetobacter subsp. xylinus and substituting the glucose in the cultivation medium by glucose phosphate as a carbon source; as well as using corn steep liquor as a nitrogen source. The investigated processing technique did not dispose any toxic chemicals that pollute the surroundings or cause unacceptable effluents, making the process environmentally safe. The fire retardant behaviour of the investigated BC has been studied by non-isothermal thermogravimetric analysis (TGA & DTGA). The activation energy of each degradation stage and the order of degradation were estimated using the Coats–Redfern equation and the least square method. Strength, optical properties, and thermogravimetric analysis of BC-phosphate added paper sheets were also tested. Conclusions: The study confirmed that the use of glucose phosphate along with glucose was significant in the high yield production of phosphate containing bacterial cellulose (PCBC1); more so than the use of glucose phosphate alone (PCBC2). Incorporating 5% of the PCBC with wood pulp during paper sheet formation was found to significantly improve kaolin retention, strength, and fire resistance properties as compared to paper sheets produced from incorporating bacterial cellulose (BC). Significance and Impact of the Study: This modified BC is a valuable product for the preparation of specialized paper, in addition to its function as a fillers aid.

Cellulose (in the form of printed paper) has always been the prime medium for displaying information in our society and is far better than the various existing display technologies. This is because of its high reflectivity, contrast, low cost and flexibility. There is a major initiative to push for a dynamic display technology that emulates paper (popularly known as "electronic paper"). We have successfully demonstrated the proof of the concept of developing a dynamic display on cellulose. To the best of our knowledge, this is the first significant effort to achieve an electronic display using bacterial cellulose. First, bacterial cellulose is synthesized in a culture of Acetobacter xylinum in standard glucose-rich medium. The bacterial cellulose membrane thus formed (not pulp) is dimensionally stable, has a paper-like appearance and has a unique microfibrillar nanostructure. The technique then involves first making the cellulose an electrically conducting (or semi-conducting) sheet by depositing ions around the microfibrils to provide conducting pathways and then immobilizing electrochromic dyes within the microstructure. The whole system is then cased between transparent electrodes, and upon application of switching potentials (2-5 V) a reversible color change can be demonstrated down to a standard pixel-sized area (ca. 100 microm2). Using a standard back-plane or in-plane drive circuit, a high-resolution dynamic display device using cellulose as substrate can be constructed. The major advantages of such a device are its high paper-like reflectivity, flexibility, contrast and biodegradability. The device has the potential to be extended to various applications, such as e-book tablets, e-newspapers, dynamic wall papers, rewritable maps and learning tools.

Suspended solids in the nutrient medium for Acetobacter xylinium in a rotating disk bioreactor become incorporated into the gelatinous mat of bacterial cellulose as it forms. Embedding fibers of ordinary cellulose creates composites with enhanced strength and the toughness of bacterial cellulose. Purified cellulose and elongated fibers from paper are incorporated differently than are spherical particles such as silica gel. About 90% of the final cellulose can come from scrap paper, and dried composite sheets were much stronger than plain bacterial cellulose per unit area.

In this report, hierarchical ZnO nano- and microstructures were directly grown for the first time on a bacterial cellulose substrate and on two additional different papers by hydrothermal synthesis without any surface modification layer. Compactness and smoothness of the substrates are two important parameters that allow the growth of oriented structures.