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The wide range of pressure detection and the exceptional linearity are essential performance parameters for flexible pressure sensors, enabling them to adapt to diverse scenarios and acquire information accurately. However, currently available "ultra‐wide range" piezoresistive sensors lack an optimal solution that effectively balances sensing properties, device thickness, and process cost. This study proposes a distinctive approach by introducing a Janus conductive structure assembled with dual resistive sensitive layers. The design allows for a pressure‐induced staged transformation of the current transport path, effectively mitigating variations and saturation in sensor resistance over a wide pressure range. The resulting piezoresistive sensor demonstrates an unprecedented detection range of 0–3800 kPa, showcasing remarkable sensitivity of 4.11 kPa−1 and outstanding linearity of 99.9% within the range of 0–1000 kPa. Additionally, the sensor boasts a thickness of only ≈200 µm, made possible through the utilization of a cellulose nanofibers material matrix. These performance achievements stand at the forefront when compared to existing reports. This research explores the potential applications of these sensors and extended arrays in the domains of human health and motion monitoring. It investigates their utility in gait analysis for assisted posture correction, as well as in the assessment and rehabilitation of gait instability. [ABSTRACT FROM AUTHOR]

In this study, we aimed at transforming naturally superhydrophilic Hanji, a traditional Korean Han paper into its superhydrophobic version. This change is crucial for applications requiring water damage resistance, such as mold growth, abrasion, and degradation. The resulting superhydrophobic Hanji shows potential for diverse applications, including fabricating wallpaper, traditional window covers, and high-end wrapping paper. To achieve this, ZnO nanoparticles (NPs) were deposited on the surface of Hanji via supersonic spraying, resulting in morphological curvatures capable of accommodating nanoscale air pockets. Additionally, supersonic spraying facilitated the robust adhesion of ZnO NPs to the Hanji cellulose fibers. Notably, the hydroxyl groups from both ZnO and Hanji were removed through subsequent annealing, resulting in superhydrophobic ZnO-Hanji. The annealing-induced shrinkage and densification of Hanji enhanced its superhydrophobicity, a property not achieved using regular A4 paper. This substantiated the unique benefits of using Hanji to realize superhydrophobicity. The superhydrophobicity reverted to superhydrophilicity upon exposure to ultra-violet irradiation, initiating reactions of the –OH group from atmospheric moisture with electron–hole pairs on the ZnO surfaces. Consequently, tunable/reversible wettability of ZnO-decorated Hanji was achieved via simple supersonic spraying and annealing, without any chemical modifications. [ABSTRACT FROM AUTHOR]

Cellulose paper has been studied for its application as an antibacterial filter, due to its robust porous structure, minimal ecological footprint, biocompatibility, and inherent antibacterial properties. Moreover, its properties can be further enhanced via surface functionalization with metallic nanoparticles (NPs) such as silver, zinc, etc. However, the synthesis of metallic NPs is challenging, costly, and environmentally harmful. On the other hand, carbon nanotubes (CNTs) are highly suitable as an additive to cellulose paper due to their high electrical conductivity, excellent mechanical strength, ease of fabrication, and antibacterial properties. In this study, we coated multi-walled carbon nanotubes (MWCNTs) on Hanji, a traditional Korean paper, using a simple dipping method and investigated its antibacterial activity against Escherichia coli (E. coli). The MWCNT-coated Hanji exhibited an inhibition efficiency of ~ 93% against E. coli cells. Moreover, the MWCNT coating resulted in improved mechanical strength, enhanced electrical conductivity, and increased hydrophobicity of the Hanji. Furthermore, it was observed that MWCNTs exhibited exceptionally stable adhesion to the Hanji surface. Our finding shows that MWCNT-coated Hanji could be utilized as an antibacterial material that is used as masks, air pollution filters, and wallpapers in hospitals and residential complexes, and an efficient platform for antiviral studies. [ABSTRACT FROM AUTHOR]

Green and sustainable power sources for next-generation electronics are being developed. A cellulose paper-based triboelectric nanogenerator (TENG) was fabricated to harness mechanical energy and convert it into electricity. This work proposes a novel approach to modify cellulose paper with natural dyes, including chlorophyll from spinach, anthocyanin from red cabbage, and curcumin from turmeric, to enhance the power output of a TENG. All the natural dyes are found to effectively improve the energy conversion performance of a cellulose paper-based TENG due to their photogenerated charges. The highest power density of 3.3 W/m2 is achieved from the cellulose paper-based TENG modified with chlorophyll, which is higher than those modified with anthocyanin and curcumin, respectively. The superior performance is attributed not only to the photosensitizer properties but also the molecular structure of the dye that promotes the electron-donating properties of cellulose. [ABSTRACT FROM AUTHOR]

A simple, environmentally friendly and efficient montmorillonite (MMT)‐metal ion (Me: Mg2+, Ca2+, Fe3+ and Zn2+)‐carboxymethyl cellulose (CMC) organic–inorganic hybrid film is successfully applied to flame retardant cellulose paper through layer‐by‐layer self‐assembly (LbL) technology. Using SEM, TGA, XPS, air permeability test and horizontal flammability test to characterize its surface morphology, thermal stability, air permeability and flame retardancy. The results show that MMT‐Me‐CMC system can endow cellulose paper with high flame retardancy properties, and different metal ions have different contributions to the flame retardancy. MMT with multi‐layer structure and high specific surface area is beneficial to reduce the air permeability of paper, thereby effectively reducing the flammability of flammable pyrolysis gas and the transfer of heat. The XPS analysis shows that the Zn2+ flame retardant system promotes the formation of graphitized char in the condensed phase. Meanwhile, the possible flame‐retardant mechanism of the system is clarified. Zn2+ replaces Al3+ in MMT, thus increasing the active acidic catalytic sites on MMT. This promotes the carbonization of degradation products and forms graphitized clay‐rich char. This work provides a simple and efficient LbL preparation strategy and provides a reference for the catalytic role of metal ions in the flame retardancy of cellulose paper. [ABSTRACT FROM AUTHOR]

Graphene is a promising reinforcement for fiber composite materials in flexible wearable applications because of its exceptional conductivity. Researchers have focused on bridging the gap between the intrinsic conductivity of graphene and the macroscopic performance of composite materials. The anisotropy of 2D nanomaterials indicates that their orientation and distribution are crucial factors in determining the macroscopic performance of thin films and bulk materials. Various technologies developed to control the formation of microstructures include electric and magnetic field methods, hot pressing, centrifugation, and freeze-drying. In this study, we prepared flexible graphene/cellulose composite film materials and used magnetic fields to regulate the orientation and distribution of graphene within cellulose paper. Results show that the grid structure of graphene arranged on the composite material produced interconnected conductive paths and reduced the graphene permeation threshold. By giving the conductive layer a higher dielectric constant, we prevented its breakdown as a conductive film. Electroluminescent devices were constructed using graphene/cellulose flexible composite materials and achieved an effective improvement in luminescence performance. Furthermore, directional luminescence was obtained through a microstructure design. This study provides a feasible path for using 2D nanomaterials in high-performance, flexible wearable devices. [ABSTRACT FROM AUTHOR]

DNA is a promising material for high density and long‐term archival data storage. In addition to algorithms for encoding digital information into DNA sequences, the DNA writing (chemical synthesis) and reading (DNA sequencing), the preservation of DNA mixtures with high sequence diversity is another critical issue for sustainable, long‐term, and large‐scale DNA data storage. Here, this work demonstrates a method for low‐cost, convenient and sustainable DNA data storage on cellulose paper. A DNA pool comprising thousands of sequences, in which archival data are encoded, is conveniently stored on a cellulose paper with a calculated density as high as 15 TB per mm3 through electrostatic adsorption. This work demonstrates that these digitally encoded DNA pools can be stable for years on the cellulose paper after drying even when directly exposed to air. Furthermore, the reversible electrostatic adsorption enables repeated loading/retrieval of DNA on/off cellulose paper. Therefore, this sustainable DNA preservation on cellulose paper through the convenient electrostatic adsorption exhibits a great advantage in terms of storage capacity and cost that is crucial for practical systems to achieve large‐scale and long‐time data storage. [ABSTRACT FROM AUTHOR]

Magnesium hydroxide (MH) has attracted considerable attention as a green flame-retardant for cellulose paper. However, conventional MH-based flame-retardant paper exhibits relatively low flame retardancy due to the low loading amount and easy agglomeration of MH. Herein, a facile method was developed to prepare MH-based flame-retardant paper with a high level of flame retardancy based on the simple and simultaneous dispersion of MgCl2 and CaO into water followed by mixing with cellulose fiber suspension before papermaking. By changing the reaction time, MH, basic magnesium chloride (BMC) or a mixture of the two can be uniformly loaded in situ onto cellulose fibers. The loaded MH, BMC or their mixture endows the cellulose paper with excellent thermal stability, flame retardancy and fire safety, especially paper loaded with a MH/BMC mixture. The excellent flame retardancy is attributed to the formation of a uniformly distributed protection layer composed of MH and BMC that acts as an endothermic flame-retardant before and after burning, which effectively blocks heat transfer and limits the release of combustible gas. This study provides a new approach for the preparation of paper with a high level of flame retardancy. [ABSTRACT FROM AUTHOR]

Green and sustainable power sources for next-generation electronics are being developed. A cellulose paper-based triboelectric nanogenerator (TENG) was fabricated to harness mechanical energy and convert it into electricity. This work proposes a novel approach to modify cellulose paper with natural dyes, including chlorophyll from spinach, anthocyanin from red cabbage, and curcumin from turmeric, to enhance the power output of a TENG. All the natural dyes are found to effectively improve the energy conversion performance of a cellulose paper-based TENG due to their photogenerated charges. The highest power density of 3.3 W/m2 is achieved from the cellulose paper-based TENG modified with chlorophyll, which is higher than those modified with anthocyanin and curcumin, respectively. The superior performance is attributed not only to the photosensitizer properties but also the molecular structure of the dye that promotes the electron-donating properties of cellulose.

The objective of this work was to develop a cellulose paper film containing a nanocomposite charge (TiO2/5%-curcumin) that allows the elimination by photocatalysis of methylene blue (MB), an organic dye, from the textile industry. The TiO2/5%-curcumin nanocomposite material was deposited on the cellulose paper by dip-coating. A continuous tubular reactor was designed and used for testing the photocatalytic degradation of aqueous MB solutions under UV irradiation. The effect of three main operational parameters on the MB photocatalytic degradation was studied: mass of TiO2/5%Curcumin material deposited on the cellulose paper, intensity of the irradiation light and initial pollutant concentration (MB). We found that by working under optimum operating conditions of material deposited mass (14 mg), initial pollutant concentration (10 ppm) and intensity of UV irradiation light (3.76 W/cm2), approximately 85% MB was eliminated after 220 min of irradiation. The kinetic study indicates that the MB photocatalytic degradation followed first-order kinetics model. The rate constant and the half-life time were (344 ± 5) × 10–4 min−1 and 20 min, respectively. Photocatalytic degradation of MB in the film containing TiO2/5%-curcumin material was improved by 12% compared to the blank film. [ABSTRACT FROM AUTHOR]

Insulation cellulose paper is a basic measure for a power transformer's remaining useful life, and its advantageous low cost, electrical, and mechanical properties have made it an extensive insulation system when impregnated in a dielectric liquid. Cellulose paper deteriorates as a result of ageing due to some chemical reactions like pyrolysis (heat), hydrolysis (moisture), and oxidation (oxygen) that affects its degree of polymerization. The condition analysis of cellulose paper has been a major concern since the collection of paper samples from an operational power transformer is almost impossible. However, some chemicals generated during cellulose paper deterioration, which were dissolved in dielectric liquid, have been used alternatively for this purpose as they show a direct correlation with the paper's degree of polymerization. Furthermore, online and non-destructive measurement of the degree of polymerization by optical sensors has been proposed recently but is yet to be available in the market and is yet generally acceptable. In mitigating the magnitude of paper deterioration, some ageing assessments have been proposed. Furthermore, researchers have successfully enhanced the insulating performance of oil-impregnated insulation paper by the addition of various types of nanoparticles. This study reviews the ageing assessment of oil-paper composite insulation and the effect of nanoparticles on tensile strength and electrical properties of oil-impregnated paper insulation. It includes not only significant tutorial elements but also some analyses, which open the door for further research on the topic. [ABSTRACT FROM AUTHOR]

Cellulose-based materials have recently drawn much interest due to their sustainability, biodegradability, biocompatibility, and low cost. In this present work, cellulose fiber paper (CFP) was fabricated from sugarcane leaves and used as a friction material for a triboelectric nanogenerator (TENG). Fe3O4 was incorporated to CFP triboelectric material to increase the dielectric constant of CFP for boosting power generation of TENG. The Fe3O4 filled CFP was synthesized using a facile one-pot co-precipitation technique. The effect of Fe3O4 content in CFP on dielectric property and TENG performance was investigated and optimized. The CFP filled with Fe3O4 nanoparticles exhibited the improved dielectric constant and possessed a superior TENG performance than pristine CF. The highest power density of 1.9 W/m2 was achieved, which was able to charge commercial capacitors serving as a power source for small electronic devices. [ABSTRACT FROM AUTHOR]

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A novel strategy is proposed to enhance the electrochemical performance of polypyrrole (PPy)‐coated cellulose paper (PCP)‐based supercapacitor by increasing the reaction interface between hydrophobic pyrrole and hydrophilic FeCl3 solution. Paper is pretreated with regenerated cellulose (RC) to increase its specific surface area, which lays the foundation for increasing the reaction interface between pyrrole and FeCl3 in the following in situ polymerization while providing more adsorption sites for PPy. The RC‐pretreated paper is first impregnated with pyrrole, followed by removing surplus pyrrole occupied by the internal pores of paper prior to the impregnation of FeCl3 solution, aiming to increase the reaction interface between pyrrole and FeCl3 solution. Consequently, the as‐prepared PCP electrode exhibits a PPy loading of 4.2 mg cm−2, which is twofold higher than unpretreated PCP electrodes (2 mg cm−2). Moreover, a solid‐state supercapacitor assembled with PCP electrodes presents a 58 mF cm−2 areal capacitance at 2 mA cm−2 (equivalent to 140.5 F g−1 at 0.5 A g−1), a 33.1 µWh cm−2 energy density at a power density of 0.60 mW cm−2, and excellent cycling stability with a capacitance retention of 91.6% after 10 000 CV cycles. This work offers a new insight toward improving the electrochemical performance of PCP‐based supercapacitor. [ABSTRACT FROM AUTHOR]

A great paradigm for foremost food packaging is to use renewable and biodegradable lignocellulose−based materials instead of plastic. Novel packages were successfully prepared from the cellulose paper by coating a mixture of polylactic acid (PLA) with cinnamaldehyde (CIN) as a barrier screen and nano silica−modified stearic acid (SA/SiO2) as a superhydrophobic layer. As comprehensively investigated by various tests, results showed that the as−prepared packages possessed excellent thermal stability attributed to inorganic SiO2 incorporation. The excellent film−forming characteristics of PLA improved the tensile strength of the manufactured papers (104.3 MPa) as compared to the original cellulose papers (70.50 MPa), enhanced by 47.94%. Benefiting from the rough nanostructure which was surface−modified by low surface energy SA, the contact angle of the composite papers attained 156.3°, owning superhydrophobic performance for various liquids. Moreover, the composite papers showed excellent gas, moisture, and oil bacteria barrier property as a result of the reinforcement by the functional coatings. The Cobb300s and WVP of the composite papers were reduced by 100% and 88.56%, respectively, and their antibacterial efficiency was about 100%. As the novel composite papers have remarkable thermal stability, tensile strength, and barrier property, they can be exploited as a potential candidate for eco−friendly, renewable, and biodegradable cellulose paper−based composites for the substitute of petroleum−derived packages. [ABSTRACT FROM AUTHOR]

• An innovative disposable in-tip cellulose paper (DICP) device has been developed. • Pristine Cellulose Paper was used as bio-based sorbent for adsorption of pesticides. • Simple design, no need for energy-consuming equipment, portable, time-efficient, and compliant with White and Green Analytical Chemistry principles. • Optimized parameters ensured robust performance, impressive detection limits, and high accuracy. • Applicability was demonstrated through successful analysis of real postmortem blood samples. Accurately identifying and quantifying toxicants is crucial for medico-legal investigations in forensic toxicology; however, low analyte concentrations and the complex samples matrix make this work difficult. Therefore, a simplified sample preparation procedure is crucial to streamline the analysis to minimize sample handling errors, reduce cost and improve the overall efficiency of analysis of toxicants. To address these challenges, an innovative disposable in-tip cellulose paper (DICP) device has been developed for the extraction of three pesticides viz. Chlorpyrifos, Quinalphos and Carbofuran from postmortem blood samples. The DICP device leverages cellulose paper strips housed within a pipette tip to streamline the extraction process, significantly reducing solvent usage, time, and labor while maintaining high analytical accuracy. The extraction of pesticides from postmortem blood using the DICP device involves a streamlined process characterized by adsorption and desorption. The diluted blood samples were processed through the DICP device via repeated aspirating and dispensing calyces to adsorb the pesticides onto the cellulose paper. The adsorbed pesticides are then eluted using acetone, which is collected for GC–MS analysis. The method was meticulously optimized, achieving a limit of quantification in the range of 0.009–0.01 µg mL−1. The intra-day and inter-day precisions were consistently less than 5 % and 10 %, respectively, with accuracy ranging from 94–106 %. Relative recoveries for the analytes were observed to be between 60 % and 93.3 %, and matrix effects were determined to be less than 10 %. The method's sustainability was validated with a whiteness score of 98.8, an AGREE score of 0.64, a BAGI score of 70 and ComplexMoGAPI score of 77. Applicability was demonstrated through successful analysis of real postmortem blood samples and proficiency testing samples, highlighting its potential utility in forensic toxicology. [ABSTRACT FROM AUTHOR]

Paper-based ion-selective optodes (ISOs) allow for low-cost ion measurements using widely accessible optical detectors such as smartphones, representing an attractive analytical platform for medical testing and environmental monitoring. Previously reported paper-based ISOs rely on plasticized PVC membranes or PVC/plasticizer-free adsorption layers containing hydrophobic sensing chemicals. In this paper, we studied a new format of paper-based ISOs, in which a plasticizer phase containing sensing chemicals is deposited onto cellulose paper without using a hydrophobic polymer like PVC. Compared to ISOs without plasticizers and polymers, the plasticizer-based ISOs show much higher pH sensitivity when using chromoionophore I and tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as the sensing chemicals. When the sensing layer further contains a solid ionophore with high molecular rigidity, the plasticizer-based ISOs for cations also exhibit enhanced sensitivity than the plasticizer-free ISOs. However, when the ionophore is a liquid at room temperature or has a long alkyl chain, the plasticizer-based and plasticizer-free ISOs have comparable responses because the ionophore behaves as a pseudo-plasticizer. Compared to ISOs with both plasticizers and polymers, the elimination of hydrophobic polymers like PVC makes inkjet printing more efficient and preserves the capillary action of the porous paper. By using the newly launched Samba cartridge with smaller nozzles, the plasticizer-based and polymer-free optodes for sodium, potassium, and calcium ions are prepared by inkjet printing for the first time. In an example application, the inkjet-printed plasticizer-based and polymer-free ISOs are used for colorimetric measurements of urine calcium. • Plasticizer-based and polymer-free ion-selective optodes are fabricated on cellulose paper. • The use of plasticizers enhances the optode performance compared to plasticizer-free optodes. • Inkjet printing of the plasticizer-based optode ink is realized using the newly launched Samba cartridge. • The inkjet-printed optodes are used for colorimetric calcium measurements in urine. [ABSTRACT FROM AUTHOR]

Novel high-performance biosensing devices, based on a microporous cellulose matrix, have been of great interest due to their high sensitivity, low cost, and simple operation. Herein, we report on the design and testing of portable paper-based immunostrips (IMS) for in-field blood typing in emergencies requiring blood transfusion. Cellulose fibrils of a paper membrane were functionalized with antibodies via supramolecular interactions. The formation of hydrogen bonds between IgM pentamer and cellulose fibers was corroborated using quantum mechanical calculations with a model cellulose chain and a representative amino acid sequence. In the proposed immunostrips, paper with a pore size of 3 µm dia. was used to enable functionalization of its channels with antibody molecules while blocking the red blood cells (RBC) from channel entering. Under the optimized test conditions, all blood types of AB0 and Rh system could be determined by naked eye examination, requiring only a small blood sample (3.5 µL). The durability of IgM immunostrips against storing has been tested. A new method of statistical evaluation of digitized blood agglutination images, compatible with a clinical five-level system, has been proposed. Critical parameters of the agglutination process have been established to enable future development of automatic blood typing with machine vision and digital data processing. [ABSTRACT FROM AUTHOR]

Hypocalcemia is caused by a sharp decline in blood calcium concentration after dairy cow calving, which can lead to various diseases or even death. It is necessary to develop an inexpensive, easy-to-operate, reliable sensor to diagnose hypocalcemia. The cellulose-paper-based microfluidic field-effect biosensor is promising for point-of-care, but it has poor mechanical strength and a short service life after exposure to an aqueous solution. Octadecyltrichlorosilane (OTS), as a popular organosilane derivative, can improve the hydrophobicity of cellulose paper to overcome the shortage of cellulose paper. In this work, OTS was used to produce the superhydrophobic cellulose paper that enhances the mechanical strength and short service life of MFB, and a microfluidic field-effect biosensor (MFB) with semiconducting single-walled carbon nanotubes (SWNTs) and DNAzyme was then developed for the Ca2+ determination. Pyrene carboxylic acid (PCA) attached to SWNTs through a non-covalent π-π stacking interaction provided a carboxyl group that can bond with an amino group of DNAzyme. Two DNAzymes with different sensitivities were designed by changing the sequence length and cleavage site, which were functionalized with SPFET/SWNTs-PCA to form Dual-MFB, decreasing the interference of impurities in cow blood. After optimizing the detecting parameters, Dual-MFB could determine the Ca2+ concentration in the range of 25 μM to 5 mM, with a detection limit of 10.7 μM. The proposed Dual-MFB was applied to measure Ca2+ concentration in cow blood, which provided a new method to diagnose hypocalcemia after dairy cow calving. [ABSTRACT FROM AUTHOR]

Cellulose paper, a material that is naturally derived, low cost, lightweight, eco-friendly, and mechanically deformable, plays important roles in producing next-generation flexible electronics. Following the booms in the development of functional electronics, the soft actuators built from cellulose paper have attracted great attention. In this focused review, the milestones and recent achievements of cellulose paper-based actuators are summarized. Electro-, thermal, moisture and magnetic actuation mechanisms are utilized to acquire energy from external stimuli. Corresponding functional materials and available fabrication techniques like film assembly and layer deposition are described. Programmable actions for the emerging applications in bionics, paper grippers and robots are realized by pursuing different strategies to control the responding deformation. Along with a conclusion, the existing challenges and possible solutions in evaluating and improving the performance of cellulose paper are summarized in the final section.

The life expectancy of power transformers is primarily determined by the integrity of the insulating oil and cellulose paper between the conductor turns, phases and phase to earth. During the course of their in-service lifetime, the solid insulating system of windings is contingent on long-standing ageing and decomposition. The decomposition of the cellulose paper insulation is strikingly grievous, as it reduces the tensile strength of the cellulose paper and can trigger premature failure. The latter can trigger premature failure, and to realize at which point during the operational life this may occur is a daunting task. Various methods of estimating the DP have been proposed in the literature; however, these methods yield different results, making it difficult to accurately estimate a reliable DP. In this work, a novel approach based on the Feedforward Backpropagation Artificial Neural Network has been proposed to predict the amount of DP in transformer cellulose insulation. Presently, no ANN model has been proposed to predict the remaining DP using 2FAL concentration. A databank comprising 100 data sets—70 for training and 30 for testing—is used to develop the proposed ANN using 2-furaldehyde (2FAL) as an input and DP as an output. The proposed model yields a correlation coefficient of 0.958 for training, 0.915 for validation, 0.996 for testing and an overall correlation of 0.958 for the model. [ABSTRACT FROM AUTHOR]

Paper is a popular platform material in all areas of sensor research due to its porosity, large surface area, and biodegradability, to name but a few. Many paper-based nanocomposites have been reported in the last decade as novel substrates for surface-enhanced Raman spectroscopy (SERS). However, there are still limiting factors, like the low density of hot spots or loss of wettability. Herein, we designed a process to fabricate a silver–chitosan nanocomposite layer on paper celluloses by a layer-by-layer method and pH-triggered chitosan assembly. Under microscopic observation, the resulting material showed a nanoporous structure, and silver nanoparticles were anchored evenly over the nanocomposite layer. In SERS measurement, the detection limit of 4-aminothiophenol was 5.13 ppb. Furthermore, its mechanical property and a strategy toward further biosensing approaches were investigated. [ABSTRACT FROM AUTHOR]

Due to intrinsic defect of fire hazard security, improving the flame retardant capacity of paper is still insufficient in case of precombustion. Herein, we integrate the flame retardant with flame detection performance on the surface of paper, the restricts of graphene oxide (GO) are overcome between high thermoelectric performance and flexibility. A flexible lamellar thermoelectric composite (GO-LA-HP) is constructed through the co-assembly of GO, ascorbic acid (LA), and phenoxycycloposphazene (HP), lamellar GO-LA-HP avoid GO's toughness decline after modification, but also enhance fire sensitivity and flame resistance. The composite could significantly decrease the temperature rise stage (<150 °C), and trigger the fire-warning within 2 s. The hybrid coating composed of phytic acid/phosphoric acid (PyA/PA) and modified thermoelectric GO-LA-HP becomes excellent compatibility on the surface of the modified paper (GPP). GPP is able to extinguish itself immediately after leaving the fire in the vertical combustion, and display the excellent flame resistance. Furthermore, GPP's alarm signal could be timely generated as little as 3 s of contacting the flame, and the response time can exceed 600 s. According to the structure observation and analysis, the related synergistic fire detection reinforcing and flame-retardant mechanisms are also proposed and clarified. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile deposition method is developed to coat cellulose paper (CP) with photocatalytic Ag-AgCl/TiO 2. • Ag-AgCl/TiO 2 /CP efficiently degrades alcoholic compounds in gas phase under sunlight. • The number of carbon atoms in VOCs significantly influences their photodegradation. • The existence of heteroatoms in VOCs hinders their mineralization process. Photocatalyst immobilization on biopolymers presents a promising avenue for air purification, yet achieving efficient immobilization and purification methods remains a challenge. In this study, we develop a novel, straightforward sequential coating technique to fabricate cellulose film embedded with uniformly dispersed TiO 2 submicrospheres and Ag-AgCl nanoparticles (NPs), tailored for effective indoor air purification under sunlight exposure. The obtained Ag-AgCl/TiO 2 /cellulose film exhibit remarkable photocatalytic prowess in degrading various volatile organic compounds (VOCs, including ethanol, 1-propanol, 1-butanol, propylamine, and propanethiol) under simulated sunlight, owing to the enhanced separation of charge carriers facilitated by the presence of plasmonic Ag-AgCl NPs. Notably, the nature of the functional groups and the carbon atom count within the VOCs molecular structures exert significant influence on the overall photocatalytic performance. Furthermore, our investigation into the reusability of this biocomposite film confirms its durability, particularly in mineralizing alcoholic compounds during VOC oxidization, and the deactivation primarily occurs with VOCs containing heteroatoms that can be residual on biocomposite surface. This study represents a significant step towards practical applications of biocomposite films with efficient photocatalytic activities for real-world air purification and environmental remediation. [ABSTRACT FROM AUTHOR]

• Modification of cellulose paper by in situ synthesis of metal-organic framework-5. • Bonding between functional groups on cellulose paper with organic ligand. • Cellulose/MOF-5 was used in the thin film solid-phase microextraction method. • Thin film showed a good ability to extraction of selective drugs in urine samples. • The method is effective, sensitive, cost-effective and have wide LDRs and low LODs. This work, reports the successful preparation a thin film by a simple and inexpensive process for quantification of a model analytes in the urine sample using HPLC-UV. To this end, cellulose paper was employed as a substrate for the in-situ synthesis of MOF-5, to increase the resistance of the prepared film. The prepared film can be reused 26 times with no reduction in its performance. The thin film prepared by MOF-5 modified cellulose substrate was utilized in thin film microextraction (TFME) method for the extraction and preconcentration of naproxen, aspirin, tolmetin, and celecoxib. Under optimal conditions, the linear dynamic range of the target analytes was 2–500 µg L −1 with correlation coefficients (R2) ranging from 0.9961 to 0.9990. Also, the limits of detection (LODs), the limits of quantification (LOQs) and relative standard deviation (RSD%) of the proposed method for selected analytes ranged between 0.57 and 0.77 µg L −1, 1.7 to 2.3 and 3.5 % to 6.2 %, respectively. Moreover, relative recoveries varied from of 94 % to 108 %, indicating the absence of matrices effect in the proposed method. Eventually, the TFME was successfully used for the extraction of selected analytes from urine samples. [ABSTRACT FROM AUTHOR]

The demand for paper-based packaging materials as an alternative to incumbent disposable petroleum-derived polymers for food packaging applications is ever-growing. However, typical paper-based formats are not suitable for use in unconventional applications due to inherent limitations (e.g., excessive hydrophilicity, lack antimicrobial ability), and accordingly, enabling new capabilities is necessity. Herein, a simple and environmentally friendly strategy was proposed to introduce antimicrobial and hydrophobic functions to cellulose paper through successive chemical grafting of 3-aminopropyltriethoxysilane (APS) and cinnamaldehyde (CA). The results revealed that cellulose paper not only showed long-term antibacterial effect on different bacteria, but also inhibited a wide range of fungi. Encouragingly, the modified paper, which is fluorine-free, displays a high contact angle of 119.7°. Thus, even in the wet state, the modified paper can still maintain good mechanical strength. Meanwhile, the multifunctional composite papers have excellent biocompatibility and biodegradability. Compared with ordinary cellulose paper, multifunctional composite paper can effectively prolong the shelf life of strawberries. Therefore, the multifunctional composite paper represents good application potential as a fruit packaging material. [ABSTRACT FROM AUTHOR]

• A novel reactive m-xylylenediamine phytate ammonium (MPAP) flame retardant was synthesized and grafted to cellulose materials. • Cellulose paper with superior flame-retardant and hydrophobic properties was successfully prepared by surface spraying technology and impregnation process, through the reaction of flame retardant and PMHS with cellulose fibers. • The modified cellulose paper also exhibited excellent performance for oil/water-separation. • This effective and simple strategy can also be applied to other cellulose-contained substrates for the application in construction, textiles, furniture and other fields. Paper-based materials have become increasingly prevalent in the packaging and daily life. However, paper is flammable and hydrophilic, hindering its widespread application. Here, a novel reactive flame retardant of m-xylylenediamine phytate ammonium (MPAP) was prepared. Cellulose paper with superior flame-retardant and hydrophobic properties was successfully prepared by surface spraying technology and impregnation process, through the reaction of flame retardant and poly(methylhydrosiloxane) (PMHS) with cellulose fibers. The water contact angle (WCA) of the modified paper was 122.6°, while the limit oxygen index (LOI) value reached 41 %, which had significant self-extinguishing performance. The total heat release rate of the modified paper was reduced from 12.8 kJ/g to 0.6 kJ/g. The modified paper also exhibited excellent performance for oil/water separation. Furthermore, this effective and simple strategy can also be applied to other cellulose-contained substrates for the application in construction, textiles, furniture and other fields. [ABSTRACT FROM AUTHOR]

The use of non-degradable plastic mulch film causes significant environmental pollution and poses a threat to human and ecological safety. To address this issue, a viable solution is to develop bio-based and biodegradable paper mulch films to replace non-biodegradable ones in agricultural soils. In this study, a green and straightforward process was used to synthesize lignin-based polyurethane (LPU), which was then coated on cellulose paper (CP) of low basis weight of 30 g/m2 to fabricate a composite LPU/CP mulch film. An ultra-thin and lightweight LPU/CP mulch film was successfully fabricated with basis weight, thickness, and specific density of 40 g/m2, 80 µm, and 0.5 g/cm3, respectively. It was observed that surface coating was very effective in improving the physical strength of composite film as indicated by the improvement of tensile index from 19.3 N·m/g of CP to 65.0 N·m/g of LPU/CP mulch film. Moreover, LPU/CP mulch film presented excellent water resistance properties as suggested by the water contact angle of 107° and the water vapor transmission rate of 639.3 g/m2·day. LPU/CP mulch film also shows a balance between degradability and durability that it starts to break down into fractions after being buried for 28 days as a result of microbiological degradation. This work provides a feasible technology for fabricating eco-friendly, cost-effective, and biodegradable paper mulch film. [Display omitted] • Lignin-based polyurethane was successfully synthesized. • LPU/CP mulch film was fabricated through LPU coating on cellulose paper. • LPU/CP mulch films showed excellent water resistance, water vapor barrier and thermal insulation performance. • Degradability and mechanical strength of LPU/CP is beneficial to agricultural application. [ABSTRACT FROM AUTHOR]

Insulation cellulose paper is a basic measure for a power transformer’s remaining useful life, and its advantageous low cost, electrical, and mechanical properties have made it an extensive insulation system when impregnated in a dielectric liquid. Cellulose paper deteriorates as a result of ageing due to some chemical reactions like pyrolysis (heat), hydrolysis (moisture), and oxidation (oxygen) that affects its degree of polymerization. The condition analysis of cellulose paper has been a major concern since the collection of paper samples from an operational power transformer is almost impossible. However, some chemicals generated during cellulose paper deterioration, which were dissolved in dielectric liquid, have been used alternatively for this purpose as they show a direct correlation with the paper’s degree of polymerization. Furthermore, online and non-destructive measurement of the degree of polymerization by optical sensors has been proposed recently but is yet to be available in the market and is yet generally acceptable. In mitigating the magnitude of paper deterioration, some ageing assessments have been proposed. Furthermore, researchers have successfully enhanced the insulating performance of oil-impregnated insulation paper by the addition of various types of nanoparticles. This study reviews the ageing assessment of oil-paper composite insulation and the effect of nanoparticles on tensile strength and electrical properties of oil-impregnated paper insulation. It includes not only significant tutorial elements but also some analyses, which open the door for further research on the topic.

The radical proliferation of pathogenic bacteria and their infections causes significant issues for human health and the environment. Today, biopolymers are used to produce different nanoparticles. In the present investigation, the fabricated chitosan/agar-silver nanoparticles (Cht/Ar-AgNPs)-coated papers were tested for antibacterial applications. Agar was used as a reducing agent for the synthesis of AgNPs. Synthesized Ar-AgNPs were examined through optical, phase crystallinity and topological analysis. Cht and Ar-AgNPs solution was mixed with various ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 by weight. In addition to that, the conformity of Cht/Ar-AgNPs-coated papers was characterized by structural, spectral, and morphological analysis. However, Cht/Ar-AgNPs-coated papers were subjected to antibacterial properties. The ratio of (6:4) Cht/Ar-AgNPs-coated paper showed excellent antibacterial agent, and it can be used as extending the food product shelf life.

Natural cellulose paper is flame retarded using ammonium polyphosphate/montmorillonite (APP/MMT) nanocompound through coating method. Their morphologies are assessed by scanning electron microscopy, chemical components by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, chemical structure by Fourier transform infrared, thermal stability by thermo-gravimetric analysis and fire retardancy by 45° horizontal burning test. The results show that the thermal stability and flame retardancy of coated paper samples are enhanced obviously, and all samples are self-extinguishing during the tests due to the char formation reaction between APP/MMT and cellulose. Then the treated paper, AM-18.3, as surface flame retardant treatment for low specific surface area (SSA) polypropylene (PP) specimens (PP@AM-18.3) also is investigated using cone calorimeter. Compared with two controlled samples, PP@AM-18.3 shows significantly increased time to ignition, the lowest fire growth index and highest fire performance index. This may give a new flame retarded approach for low SSA polymer materials with little amount flame retardants. [ABSTRACT FROM AUTHOR]

Abstract It has been a research goal to develop macroscopic materials with an optimized surface structure to affix silver nanoparticles which could contaminate water and maximize their practical functions. Cellulose paper is a versatile biomass material valued for its abundance, low cost, biocompatibility, and natural composition. Until now, its potential application in water purification has not been adequately explored. In this study, gallic acid-modified silver nanoparticles (GA@AgNPs) were loaded onto commercial cellulose filter paper using a simple lipoic acid modification process (GA@AgNPs-LA-CP). Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were used to characterize the GA@AgNPs-LA-CP. The catalytic activity of the GA@AgNPs-LA-CP was evaluated by the reduction reaction of methylene blue (MB), Rhodamine B (RhB), and 4-nitrophenol (4-NP) with sodium borohydride (NaBH4). The GA@AgNPs-LA-CP exhibited excellent catalytic activity toward MB, RhB, and 4-NP, taking advantage of its high specific surface area generated by the cellulose fiber network structure. Interestingly, due to the electrostatic interactions between the cationic dyes and the GA@AgNPs, the as-prepared catalytic composite material serves as a better catalyst for MB and RhB, suggesting dual applications of the composite materials for organic wastewater treatment and the removal of harmful dyes. This implies that the immobilization of AgNPs on cellulose papers is an effective method and can be applied to efficient wastewater treatment applications. Graphical abstract

Paper-based microfluidic devices based on electrowetting principle, more specifically electrowetting on dielectric (EWOD), have attracted increasing attention due to their powerful liquid handling capability as compared to continuous-flow paper-based analytical devices (μPAD) that use capillary effects to control liquids. Here, we demonstrate fabrication of paper-based EWOD devices using cellulose paper as substrate and paraffin wax as dielectric hydrophobic layer by a simple pressing treatment for the cellulose paper and melting or spray-coating of paraffin wax. We optimized the key fabrication parameters according to the surface morphology and hydrophobicity of the obtained wax film, including the pressing pressure, thermal annealing temperature and amount of paraffin wax. Moreover, the EWOD devices fabricated by the spray-coating method demonstrate larger contact angle changes but with smaller contact angle hysteresis under DC electric field when compared with the devices fabricated by the melting method. Our study opens up potential fabrication of hybrid paper-based microfluidic device combining advantages of continuous-flow and electrowetting using cellulose paper and paraffin wax.

Cellulose-based materials have recently drawn much interest due to their sustainability, biodegradability, biocompatibility, and low cost. In this present work, cellulose fiber paper (CFP) was fabricated from sugarcane leaves and used as a friction material for a triboelectric nanogenerator (TENG). Fe3O4 was incorporated to CFP triboelectric material to increase the dielectric constant of CFP for boosting power generation of TENG. The Fe3O4 filled CFP was synthesized using a facile one-pot co-precipitation technique. The effect of Fe3O4 content in CFP on dielectric property and TENG performance was investigated and optimized. The CFP filled with Fe3O4 nanoparticles exhibited the improved dielectric constant and possessed a superior TENG performance than pristine CF. The highest power density of 1.9 W/m2 was achieved, which was able to charge commercial capacitors serving as a power source for small electronic devices.

Developing highly efficient electromagnetic interference (EMI) shielding materials with outstanding mechanical properties are urgently desirable for portable device hardware and flexible electronic devices. Herein, a highly conductive and flexible silver nanowires/graphene nanosheets/cellulose (AgNWs/GNSs/cellulose) composite paper with particular three‐layered structures is fabricated via vacuum assisted filtered and coating method. The prepared composites exhibit excellent EMI shielding property due to the unique layered structure. By changing the order of the conductive layers, the overall shielding performance can be further improved. An outstanding EMI shielding effectiveness (SE) of 53.3 dB is achieved with a thickness of only 0.17 mm. The composites show prominent bending resistance, which is proved by 1000 times of repeated bending leading to no obvious changes in structure. Moreover, the prepared composites exhibit excellent mechanical properties. Therefore, it is expected that this work will open up a facile strategy for exploiting materials with excellent EMI shielding properties and mechanical performance. [ABSTRACT FROM AUTHOR]

Magnetic carbon fiber sheet (MCP) has been successfully prepared by novel one-step flash carbonization and magnetization method using cellulose paper as carbon source and iron(III) chloride and manganese chloride as magnetic source. The as-prepared MCP is systematically characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, nitrogen physical adsorption (BET) and thermal gravimetric analysis. Congo red (CR) and methylene blue (MB) are employed as the typical anionic and cationic probe pollutant to assess the adsorption performance of the as-prepared MCP, respectively. The adsorption results from aqueous media using a batch technique show that the adsorption can be well described by the pseudo-second-order kinetic and Langmuir isotherm models for anionic CR and cationic MB. The estimated thermodynamic constants indicated that the adsorption is a spontaneous, endothermic process. The maximum adsorption capacity values reach 245 and 140 mg g-1 for CR and MB, respectively. The flash carbonization and synchronous magnetization with cellulose paper can be anticipated to be a good route for resource utilization of wastepaper. [ABSTRACT FROM AUTHOR]

Molecularly imprinted polymers are efficient and selective adsorbents which act as artificial receptors for desired compounds with the ability to recognize the size, shape, and functional groups of the compounds simultaneously. A molecularly imprinted polymer is prepared by the polymerization of functional monomers around a template (analyte) molecule. Afterward, the removal of the template from the polymer matrix leaves a selective cavity behind. The fabrication and development of molecularly imprinted polymers grew rapidly, due to their low cost, simple preparation, selectivity, sensitivity, and stable physicochemical properties. Traditionally, molecularly imprinted polymers can be synthesized using two main methods, namely bulk and surface imprinting. For more efficient use of the latter method, researchers have developed molecularly imprinted polymers grafted on the solid-phase matrix (substrate). This grafting technique would be particularly useful for surface imprinting of macromolecules, such as proteins. Cellulose fibers of papers with unique properties such as being abundant, retaining a porous structure, having good adsorption properties, and possessing hydroxyl groups naturally have gained much attention as substrate. The goal of this review is to introduce molecularly imprinted polymer-grafted or molecularly imprinted polymer-coated paper, as an interesting, simple, and efficient method in the detection and separation of small and large molecules. Therefore, in the present paper, several recent preparation techniques and applications of molecularly imprinted polymer-grafted paper are reviewed and discussed in detail. [ABSTRACT FROM AUTHOR]

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A simple and an available method is proposed for the determination of quinolone antibiotics using solid-phase fluorescence digital colorimetry. The intrinsic fluorescence of 17 quinolones and the quinolone-sensitizedfluorescence of europium on cellulose paper (CP) and a thin silica layer are studied. Upon the irradiation of quinolone solutions applied to a matrix with ultraviolet light (365 nm), blue (CP, high-performance thin-layer chromatography (HPTLC)) and pink (CP–Eu, HPTLC–Eu) fluorescence is observed. Measurement of the fluorescence intensity on the surface of matrices is carried out using a smartphone. The values of colorimetric parameters in the RGB system are used as the analytical signal (Ar): Ar = The limits of detection and determination are 0.2–4 and 0.6–12 µg/mL, respectively, for all analyzed analytes. The analytical ranges are 0.6–500 µg/mL. A procedure for the determination of fluoroquinolones in medicinal preparations is proposed. The relative standard deviation of the results of analysis does not exceed 5%. [ABSTRACT FROM AUTHOR]

The microstructure plays an important role in improving the sensing performance of pressure sensor. However, the design of microstructural active layer of pressure sensor usually involves complex process and expensive raw materials. Herein, the common polyester conductive electrodes and cellulose paper that both have inherent microstructure surface are combined to form two-sided microstructure interfaces for low-cost, eco-friendly and high-performance flexible piezoresistive pressure sensor. In order to obtain conductive and low-cost active layer paper, daily carbon ink, which is usually used for writing, is preferred as a conductive material. Meanwhile, we experimentally confirm that the proposed structure is also suitable for other conductive materials, such as carbon nanotubes. The results show that as-fabricated piezoresistive sensor has high pressure sensitivities of 5.54 and 1.61 kPa−1 in the wide linear ranges of 0.5 − 5 and 5 − 60 kPa, respectively, and good durability (5000 cycles under 2 kPa). The sensing mechanism of the piezoresistive sensor is analyzed by combining the characterization results and finite element simulation. Benefitting from the high sensing performance and good flexibility, the piezoresistive sensor is demonstrated for multiple wearable applications (e.g., wrist pulse, speech recognition, finger bending, abdominal respiration, counting steps, and pressure distribution). This work provides a simple and effective strategy for the design of piezoresistive sensor from the microstructure interfaces between electrodes and active layer. [ABSTRACT FROM AUTHOR]

A great paradigm for foremost food packaging is to use renewable and biodegradable lignocellulose−based materials instead of plastic. Novel packages were successfully prepared from the cellulose paper by coating a mixture of polylactic acid (PLA) with cinnamaldehyde (CIN) as a barrier screen and nano silica−modified stearic acid (SA/SiO2) as a superhydrophobic layer. As comprehensively investigated by various tests, results showed that the as−prepared packages possessed excellent thermal stability attributed to inorganic SiO2 incorporation. The excellent film−forming characteristics of PLA improved the tensile strength of the manufactured papers (104.3 MPa) as compared to the original cellulose papers (70.50 MPa), enhanced by 47.94%. Benefiting from the rough nanostructure which was surface−modified by low surface energy SA, the contact angle of the composite papers attained 156.3°, owning superhydrophobic performance for various liquids. Moreover, the composite papers showed excellent gas, moisture, and oil bacteria barrier property as a result of the reinforcement by the functional coatings. The Cobb300s and WVP of the composite papers were reduced by 100% and 88.56%, respectively, and their antibacterial efficiency was about 100%. As the novel composite papers have remarkable thermal stability, tensile strength, and barrier property, they can be exploited as a potential candidate for eco−friendly, renewable, and biodegradable cellulose paper−based composites for the substitute of petroleum−derived packages.

Novel high-performance biosensing devices, based on a microporous cellulose matrix, have been of great interest due to their high sensitivity, low cost, and simple operation. Herein, we report on the design and testing of portable paper-based immunostrips (IMS) for in-field blood typing in emergencies requiring blood transfusion. Cellulose fibrils of a paper membrane were functionalized with antibodies via supramolecular interactions. The formation of hydrogen bonds between IgM pentamer and cellulose fibers was corroborated using quantum mechanical calculations with a model cellulose chain and a representative amino acid sequence. In the proposed immunostrips, paper with a pore size of 3 µm dia. was used to enable functionalization of its channels with antibody molecules while blocking the red blood cells (RBC) from channel entering. Under the optimized test conditions, all blood types of AB0 and Rh system could be determined by naked eye examination, requiring only a small blood sample (3.5 µL). The durability of IgM immunostrips against storing has been tested. A new method of statistical evaluation of digitized blood agglutination images, compatible with a clinical five-level system, has been proposed. Critical parameters of the agglutination process have been established to enable future development of automatic blood typing with machine vision and digital data processing.

Hypocalcemia is caused by a sharp decline in blood calcium concentration after dairy cow calving, which can lead to various diseases or even death. It is necessary to develop an inexpensive, easy-to-operate, reliable sensor to diagnose hypocalcemia. The cellulose-paper-based microfluidic field-effect biosensor is promising for point-of-care, but it has poor mechanical strength and a short service life after exposure to an aqueous solution. Octadecyltrichlorosilane (OTS), as a popular organosilane derivative, can improve the hydrophobicity of cellulose paper to overcome the shortage of cellulose paper. In this work, OTS was used to produce the superhydrophobic cellulose paper that enhances the mechanical strength and short service life of MFB, and a microfluidic field-effect biosensor (MFB) with semiconducting single-walled carbon nanotubes (SWNTs) and DNAzyme was then developed for the Ca2+ determination. Pyrene carboxylic acid (PCA) attached to SWNTs through a non-covalent π-π stacking interaction provided a carboxyl group that can bond with an amino group of DNAzyme. Two DNAzymes with different sensitivities were designed by changing the sequence length and cleavage site, which were functionalized with SPFET/SWNTs-PCA to form Dual-MFB, decreasing the interference of impurities in cow blood. After optimizing the detecting parameters, Dual-MFB could determine the Ca2+ concentration in the range of 25 μM to 5 mM, with a detection limit of 10.7 μM. The proposed Dual-MFB was applied to measure Ca2+ concentration in cow blood, which provided a new method to diagnose hypocalcemia after dairy cow calving.

Developing new energy technology is a significant challenge in the context of the energy crisis. As a novel energy conversion device to convert mechanical energy into electricity, the triboelectric nanogenerator (TENG) has attracted significant attention in the past few years. The choice of component materials directly affects the cost, environmental performance, output performance, and preparation process of a TENG. In recent years, cellulose paper has become an ideal material for fabricating a TENG due to its lightweight, biodegradability, low‐cost, high flexibility, environmental friendliness, porosity, and easy modification. Cellulose paper‐based TENG has become a hot topic in the field of green energy. This paper systematically summarizes the research progress of the cellulose paper‐based TENG. The advantages of cellulose paper as raw material to fabricate a TENG, followed by introducing the different roles of cellulose paper in paper‐based TENGs, are first discussed. Then the recent progress in energy storage, performance optimization methods, hybridization, and applications of cellulose paper‐based TENGs is successively elaborated. Finally, some perspectives and challenges for the future development of cellulose paper‐based TENG are discussed to provide guidance. [ABSTRACT FROM AUTHOR]

Heavy metal cations are important in our daily life and may cause serious disorders and diseases. Colorimetric portable cellulosic sensors with high selectivity and sensitivity toward metal cations are preferred relative to those based on small molecules which operate mostly in organic media and difficult test methods. Here, dual-chromic stimuli-responsive cellulose paper (TPL@T-Cell) was produced by modification of the paper with the designed and prepared epoxy-functionalized polyacrylic nanocapsules via dip-coating and subsequent heat treatment processes. The capsules contained thermochromic leuco-dye derivative and photochromic hydroxyl-functionalized spiropyran and were prepared through semi-continuous miniemulsion polymerization. Chemical structure of the synthesized dyes, nanocapsules and modified cellulose fibers were identified by FTIR and UV-Vis analyses. Spherical morphology of the prepared nanocapsules with average particles size of 121 nm were observed by SEM and DLS analyses. The effective wetting of the cellulose fibers by nanocapsules with proper diffusion and deposition through the establishment of physical and chemical interactions were evaluated by SEM and ATR-FTIR analyses, respectively. The prepared TPL@T-Cell sensor revealed distinct color changes toward Fe2+, Pb2+ and Sn2+ ions. Opto-chemical results indicated that detection limit of TPL@T-Cell for Sn2+ (0.0028 µM, 0.326 ppb), Fe2+ (0.0013 µM, 0.15 ppb), and Pb2+ (0.0023 µM, 0.268 ppb) are lower than their critical permitted levels announced by WHO. These exhibited applicability of TPL@T-Cell sensor for determining trace amount of some heavy metal ions with instant responsivity, wide linear detection range, high sensitivity, and low detection limit via colorimetric and spectroscopic responses. [Display omitted] • Modification of stimuli-responsive cellulose paper via dip-coating technique. • Preparation of dual-chromic nanocapsules containing leuco dye and spiropyan. • Opto-chemical and spectroscopic features of the fabricated chemosensor. • Application of the cellulose-based sensor for colorimetric detection of heavy metal cations. • Responsivity, sensitivity and LOD assessment of the prepared cellulosic sensor. [ABSTRACT FROM AUTHOR]

Cellulose material is a dielectric with intricate microscopic relaxation processes due to its complex structure. However, conventional models and curve fitting methods used for tracing and analyzing these processes often fail to capture crucial dielectric information. This paper aimed to extract the Distribution of Relaxation Time (DRT), the most fundamental and effective dielectric information providing the time scale and relative contribution of all microscopic relaxation processes. First, a distributed extended Debye model with infinite branches was constructed based on the microscopic nature of dielectric relaxation. Then, an implicit equation of the DRT function was established, inspired by the mathematical principles of infinite subdivision and summation. To obtain the numeral solution of the DRT function, a regularization method was proposed and validated. Finally, the approach was applied to cellulose insulating paper with varying degradation degrees. The relaxation process with a long time constant played a significant role, and variations during the degradation process were attributed to reduced activation energy. With clear physical interpretation and robust mathematical foundation, our method sheds light on the intricate dielectric relaxation processes in cellulose. This not only enhances the theoretical understanding and practical application of cellulose materials but also provides valuable insights for the analysis and application of other materials. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Paper-based modification for a CA15-3 self-indicated test-strip. • Paper modified with a molecularly imprinted polymer (MIP) for CA15-3. • Paper with MIP concentrates (selectively) CA15-3 on its surface. • Coloured signal generated by reaction of TMB substrate with a peroxidase. • Peroxidase enzyme action upon substrate controls the colour intensity. The combination of molecularly-imprinted polymers (MIPs) on paper substrates for capturing a cancer antigen 15–3 (CA15-3) with the traditional coloured transduction scheme of enzyme-linked immunosorbent assay (ELISA) using 3,3′,5,5′-tetramethylbenzidine (TMB), horseradish peroxidase (HRP) and H 2 O 2 is presented here for the first time. Here, the paper surface was modified with a silane derivative containing an amine function that allows subsequent binding of 3-aminophenylboronic acid (3-APBA). The target protein, CA15-3, was then bound via the boronic groups of APBA. The empty space around CA15-3 was filled by polymerization of dopamine. Finally, the CA15-3 template was removed by breaking the imine function to create vacant sites for which CA15-3 has a high affinity. Binding of CA15-3 was detected by oxidation of TMB substrate by HRP in the presence of H 2 O 2. The results showed that the MIP was able to selectively recognize CA15-3 within 3–500 U mL−1, even in complex samples. Quantitative data were extracted by analysing the colour coordinates of images captured with a smartphone using ImageJ. This selective behaviour was confirmed by comparison with a control material (non– polymer, NIP). Overall, the described approach has advantages over conventional ELISA, namely low cost and high stability, which is due to the use of MIP as a trapping element acting as a selective pre-concentration point of CA15-3. To our knowledge, this is the first biomimetic ELISA (B-ELISA) on paper substrate used for macromolecules such as proteins. We believe that this approach has the potential to be applied to other protein disease biomarkers, making it a suitable tool for screening glycoproteins at the point-of-care. [ABSTRACT FROM AUTHOR]