Nanocrystalline cellulose applied simultaneously as the gate dielectric and the substrate in flexible field effect transistors

The Improved Redispersibility of Cellulose Nanocrystals Using Hydroxypropyl Cellulose and Structure Color from Redispersed Cellulose Nanocrystals

Cellulose nanocrystals (CNC) have been significantly developed as a building block material for the design of novel functional materials in many fields such as biomedicine, nanotechnology, and materials science due to their excellent optical properties, biocompatibility, and sustainability. Improving the redispersibility of CNC in the sustainable processing of nanocellulose has been a challenge because intense hydrogen bond interaction leads to irreversible aggregation, making CNC difficult to redisperse and increasing the cost of storage and transportation of CNC. Hydroxypropyl cellulose (HPC) is an important hydroxy propylated cellulose ether. As a water-soluble cellulose derivative, HPC has a polyhydroxy structure similar to that of CNC, which leads to good compatibility and high affinity between HPC and CNC. In this work, HPC of different molecular weights was comixed with CNC of different contents, which was then dried using different methods, and the dried samples were redispersed in water. The addition of HPC improved the redispersibility of the CNC. Finally, the redispersed suspension was also redried to form a film, which was found to retain its structure color. These results provide an important avenue for the redispersion of dried CNC and for the development of functional materials from redispersed CNC.

How Far Is the Nanocellulose Chip and Its Production in Reach? A Literature Survey

The slowdown of Moore's Law necessitates an exploration of novel computing methodologies, new materials, and advantages in chip design. Thus, carbon-based materials have promise for more energy-efficient computing systems in the future. Moreover, sustainability emerges as a new concern for the semiconductor industry. The production and recycling processes associated with current chips present huge environmental challenges. Electronic waste is a major problem, and sustainable solutions in computing must be found. In this review, we examine an alternative chip design based on nanocellulose, which also features semiconductor properties and transistors. Our review highlights that nanocellulose (NC) is a versatile material and a high-potential composite, as it can be fabricated to gain suitable electronic and semiconducting properties. NC provides ideal support for ink-printed transistors and electronics, including green paper electronics. Here, we summarise various processing procedures for nanocellulose and describe the structure of exclusively nanocellulose-based transistors. Furthermore, we survey the recent scientific efforts in organic chip design and show how fully automated production of such a full NC chip could be achieved, including a Process Design Kit (PDK), expected variation models, and a standard cell library at the logic-gate level, where multiple transistors are connected to perform basic logic operations-for instance, the NOT-AND (NAND) gate. Taking all these attractive nanocellulose features into account, we envision how chips based on nanocellulose can be fabricated using Electronic Design Automation (EDA) tool chains.

Enhancing the High-Solid Anaerobic Digestion of Horticultural Waste by Adding Surfactants

The influence of adding surfactants on the performance of high-solid anaerobic digestion of horticultural waste was extensively investigated in batch systems. Adding Tween series and polyethylene glycol series non-ionic surfactants had positive effects on biogas production, resulting in 370.1 mL/g VS and 256.6 mL/g VS with Tween 60 and polyethylene glycol 300 at a surfactant-to-grass mass ratio of 0.20, while the biogas production of anaerobic digestion without surfactants was 107.54 mL/g VS. The optimal and economically feasible choice was adding Tween 20 at a ratio of 0.08 g/g grass in high-solid anaerobic digestion. A kinetics model reliably represented the relationship between surfactant concentration and biogas production. The mechanism of surfactants working on lignocellulose was investigated. The improvement in high-solid anaerobic digestion by adding surfactants was attributed to the interaction between lignocelluloses and surfactants and the extraction of biodegradable fractions from the porous structure. An economic analysis showed that adding Tween 20 was likely to make a profit and be more feasible than adding Tween 60 and polyethylene glycol 300. This study confirms the enhancement in biogas production from horticultural waste by adding non-ionic surfactants.

Transparent Structures for ZnO Thin Film Paper Transistors Fabricated by Pulsed Electron Beam Deposition

Thin film transistors on paper are increasingly in demand for emerging applications, such as flexible displays and sensors for wearable and disposable devices, making paper a promising substrate for green electronics and the circular economy. ZnO self-assembled thin film transistors on a paper substrate, also using paper as a gate dielectric, were fabricated by pulsed electron beam deposition (PED) at room temperature. These self-assembled ZnO thin film transistor source-channel-drain structures were obtained in a single deposition process using 200 and 300 µm metal wires as obstacles in the path of the ablation plasma. These transistors exhibited a memory effect, with two distinct states, "on" and "off", and with a field-effect mobility of about 25 cm2/Vs in both states. For the "on" state, a threshold voltage (Vth on = -1.75 V) and subthreshold swing (S = 1.1 V/decade) were determined, while, in the "off" state, Vth off = +1.8 V and S = 1.34 V/decade were obtained. A 1.6 μA maximum drain current was obtained in the "off" state, and 11.5 μA was obtained in the "on" state of the transistor. Due to ZnO's non-toxicity, such self-assembled transistors are promising as components for flexible, disposable smart labels and other various green paper-based electronics.

CaCu3Ti4O12 nanoparticle-loaded cotton fabric for dual photocatalytic antibacterial and dye degradation applications

CaCu3Ti4O12 (CCTO) nanoparticles (NPs) were screen printed on pristine cotton fabric. The CCTO-coated fabric was characterized using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), Raman, X-ray diffraction (XRD), x-ray photoelectron spectrometer (XPS), and field emission-scanning electron microscopy (FE-SEM). The modified fabric photocatalytic antibacterial and dye-degradation abilities were assessed. After 2 h of bacterial contact, unwashed CCTO-embedded cotton reduced E. coli and S. aureus by 95.1% and 94.3%, respectively. After 20 washing cycles, the modified fabric was able to eliminate S. aureus and E. coli by more than 85%. The cloth coated with CCTO-NPs degraded the methylene blue (MB) dye by 82% in 4 h, as opposed to the pure cotton's 11% degradation rate. The embedding of CCTO-NPs onto the cotton surface had minimal effect on fabric intrinsic properties like tensile strength, abrasion resistance, and water-vapor permeability.

Preparation of cellulose nanocrystal (CNCs) reinforced polylactic acid (PLA) bionanocomposites filaments using biobased additives for 3D printing applications

This work presents the experimental steps taken towards the preparation of 3D printable bionanocomposites using polylactic acid (PLA) biopolymer containing 0.1, 0.5 and 1 wt% CNCs. Optimized amounts of bio-based additives were added to improve the processability and flexibility of the bionanocomposites. The 3D printable bionanocomposite filaments were drawn using a single screw extruder. The bionanocomposites filament was used to 3D print prototypes and test specimens for dynamic mechanical analysis (DMA). Characterization of the CNCs and bionanocomposites was performed using Fourier Transform Infrared Spectroscopy (FTIR) analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The nucleating effect of CNCs enhanced the crystallization behaviour of bionanocomposites by 5%, 15% and 11%, for the different CNCs loadings. The TGA analysis revealed a ∼20 °C improvement in the thermal stability of the bionanocomposites. Meanwhile, the tensile analysis showed a ≥48% increase in the tensile strength of the bionanocomposites filaments which was attributed to the reinforcing effects of CNC. The addition of CNCs significantly increased the melt viscosity, storage and loss modulus of PLA. In summary, the bionanocomposite filaments produced in this study exhibited excellent processibility and superior mechanical and thermal properties.

Sodium Alginate-Aldehyde Cellulose Nanocrystal Composite Hydrogel for Doxycycline and Other Tetracycline Removal

A novel composite hydrogel bead composed of sodium alginate (SA) and aldehyde cellulose nanocrystal (DCNC) was developed for antibiotic remediation through a one-step cross-linking process in a calcium chloride bath. Structural and physical properties of the hydrogel bead, with varying composition ratios, were analyzed using techniques such as BET analysis, SEM imaging, tensile testing, and rheology measurement. The optimal composition ratio was found to be 40% (SA) and 60% (DCNC) by weight. The performance of the SA-DCNC hydrogel bead for antibiotic remediation was evaluated using doxycycline (DOXY) and three other tetracyclines in both single- and multidrug systems, yielding a maximum adsorption capacity of 421.5 mg g^-1 at pH 7 and 649.9 mg g^-1 at pH 11 for DOXY. The adsorption mechanisms were investigated through adsorption studies focusing on the effects of contact time, pH, concentration, and competitive contaminants, along with X-ray photoelectron spectroscopy analysis of samples. The adsorption of DOXY was confirmed to be the synergetic effects of chemical reaction, electrostatic interaction, hydrogen bonding, and pore diffusion/surface deposition. The SA-DCNC composite hydrogel demonstrated high reusability, with more than 80% of its adsorption efficiency remaining after five cycles of the adsorption-desorption test. The SA-DCNC composite hydrogel bead could be a promising biomaterial for future antibiotic remediation applications in both pilot and industrial scales because of its high adsorption efficiency and ease of recycling.

A mini-review on the dielectric properties of cellulose and nanocellulose-based materials as electronic components

Cellulose-based materials have the advantages of renewable, non-toxic, flexible, and strong mechanical properties, so it of is great significance to study the dielectric properties of cellulose-based materials. In this paper, we summarized the factors influencing the dielectric properties of cellulose and nanocellulose-based dielectric and the ways to change the dielectric properties, mainly exploring the methods to improve the dielectric constant of cellulose-based dielectric materials. Cellulose and nanocellulose-based dielectric need to improve the hygroscopic property, increase the flexibility and reduce dielectric loss of the composite materials. This review summarizes the current state-of-art progress of new dielectric materials for green energy storage and flexible electronic devices.

Simultaneous removal of aqueous same ionic type heavy metals and dyes by a magnetic chitosan/polyethyleneimine embedded hydrophobic sodium alginate composite: Performance, interaction and mechanism

Heavy metals and azo dyes caused huge harm to the aqueous system and human health. A magnetic chitosan/polyethyleneimine embedded hydrophobic sodium alginate composite (MCPS) was designed and prepared to simultaneously remove aqueous same ionic type heavy metals and azo dyes. In mono-polluted system, the optimal pH for Cr(VI), MO (methyl orange), Cu(Ⅱ) and MB (methylene blue) were 3, 2, 6 and 12 with a saturated adsorption capacity of 87.53, 66.41, 351.03 and 286.54 mg/g, respectively. Pseudo-second-order was suitable to describe the adsorption kinetics of them and the adsorption isotherms were more consistent with the Langmuir isotherm model being a spontaneous, endothermic, and entropy-increasing process. In binary-polluted system, MCPS possessed simultaneous adsorption for Cr (Ⅵ)-MO and Cu(Ⅱ)-MB pollutants at their optimal pH, in addition, whether in anionic or cationic solution, the removal of heavy metals were promoted with the add of azo dyes but the removal of azo dyes were suppressed with the add of heavy metals. Both Cr (Ⅵ)-MO and Cu(Ⅱ)-MB pollutants could be effectively adsorbed and desorbed from MCPS by changing the pH of the aqueous solution to realize recyclability. Lastly, removal mechanism was revealed in detail by FT-IR, EDS and XPS.

Highly stable, antiviral, antibacterial cotton textiles via molecular engineering

Cotton textiles are ubiquitous in daily life and are also one of the primary mediums for transmitting viruses and bacteria. Conventional approaches to fabricating antiviral and antibacterial textiles generally load functional additives onto the surface of the fabric and/or their microfibres. However, such modifications are susceptible to deterioration after long-term use due to leaching of the additives. Here we show a different method to impregnate copper ions into the cellulose matrix to form a copper ion-textile (Cu-IT), in which the copper ions strongly coordinate with the oxygen-containing polar functional groups (for example, hydroxyl) of the cellulose chains. The Cu-IT displays high antiviral and antibacterial performance against tobacco mosaic virus and influenza A virus, and Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa and Bacillus subtilis bacteria due to the antimicrobial properties of copper. Furthermore, the strong coordination bonding of copper ions with the hydroxyl functionalities endows the Cu-IT with excellent air/water retainability and superior mechanical stability, which can meet daily use and resist repeated washing. This method to fabricate Cu-IT is cost-effective, ecofriendly and highly scalable, and this textile appears very promising for use in household products, public facilities and medical settings.

Zwitterionic ammonium-sulfonato grafted cellulose for efficient thallium removal and adsorption mechanism study

Thallium (Tl) has posed serious impacts on human being concerning increasingly serious pollution in aqueous environments. However, little information on removal method than conventional heavy metals have been available. In the present work, zwitterionic N-(3-sulfonato-1-propyl)-N,N-dimethylammonium grafted cellulose fibre (DMAE-PS) has been fabricated. The chemical component, thermal stability and surface properties of as-prepared materials are identified by FT-IR, elemental analysis, TGA, XRD, BET and SEM. DMAE-PS is shown to be very efficient for removing Tl(I) from water samples with a loading capacity of 274.7 mg (Tl(I))·g^-1 (DMAE-PS)_, representing one of the best performances among bio-mass derived materials. The adsorption is consistent with the Freundlich model following a pseudo-second order (K₂ = 4.36 × 10^-4 g·mg^-1·min^-1, R² = 0.999) and two-step intra-particle diffusion kinetics. The selectivity towards Tl(I) is also remarkably, 1-2 orders (distribution ratio K_Tl/M = 14.85-289.29) of magnitude larger than competing metals (Zn²⁺, Cr³⁺, Mn²⁺, Cu²⁺ and Cd²⁺). The SEM, XPS and UV-visible spectrum collectively reveal that -SO₃^--Tl(I) ionic interaction is probably the main driving force for specific adsorption, which shows a high stability against pH variation. The fabricated DMAE-PS is a sustainable bio-adsorbent with synthetic availability, high removing capacity and strong selectivity, therefore, potentially feasible in treatment of Tl(I) polluted environmental samples.

Ion-Incorporative, Degradable Nanocellulose Crystal Substrate for Sustainable Carbon-Based Electronics

Electronic wastes from transient electronics accumulate biologically harmful materials with global concern. Recycling these wastes could prevent the deposition of hazardous chemicals and toxic materials to the environment while saving scarce natural compounds and valuable resources. Here, we report a sustainable electronic device, taking advantage of carbon resources and a biodegradable cellulose composite. The device consists of an ambient-stable carbon nanotube as a semiconductor, graphene as electrodes, and a free-standing cellulose filter paper/nanocellulose composite as a dielectric layer. The dual-functional cellulose composite acting simultaneously as a robust substrate and a dielectric is demonstrated, which is compatible with solution device fabrication processes. An optimized channel dimension of 5 mm × 3 mm with the addition of ions that facilitates a charge transport realized a device with an on-current per width of 9.6 μA mm^-1, an on/off ratio >10², a field-effect mobility of 2.03 cm² V^-1 s^-1, and long-term stability over 30 days under ambient conditions. Successful separation of the carbonaceous components via an eco-friendly solution sorting protocol allowed the recycled device to display excellent electronic performance, with a recapture efficiency of 90%. This effort demonstrates a processable, low-cost, and sustainable electronic system that can be applied in the current realm of the semiconducting and sensing industry.

Cellulose Nanocrystal Aqueous Colloidal Suspensions: Evidence of Density Inversion at the Isotropic-Liquid Crystal Phase Transition

The colloidal suspensions of aqueous cellulose nanocrystals (CNCs) are known to form liquid crystalline (LC) systems above certain critical concentrations. From an isotropic phase, tactoid formation, growth, and sedimentation have been determined as the genesis of a high-density cholesteric phase, which, after drying, originates solid iridescent films. Herein, the coexistence of a liquid crystal upper phase and an isotropic bottom phase in CNC aqueous suspensions at the isotropic-nematic phase separation is reported. Furthermore, isotropic spindle-like domains are observed in the low-density LC phase and high-density LC phases are also prepared. The CNCs isolated from the low- and high-density LC phases are found to have similar average lengths, diameters, and surface charges. The existence of an LC low-density phase is explained by the presence of air dissolved in the water present within the CNCs. The air dissolves out when the water solidifies into ice and remains within the CNCs. The self-adjustment of the cellulose chain conformation enables the entrapment of air within the CNCs and CNC buoyancy in aqueous suspensions.

Recycled Paper Sludge (RPS)-Derived Nanocellulose: Production, Detection and Water Treatment Application

Paper production and recycling result in large amounts of recycled paper sludge (RPS) that is currently being disposed of in very costly and unsustainable practices, raising the importance of developing green solutions for waste management. The use of nanocellulose (NC) as the next generation of materials has gained much attention due to its economic potential. However, there are substantial challenges in NC extraction, detection, and quantification methods. In this study, NC was produced from RPS as a means of converting waste into a resource. The process included a short, 30 min ozonation (21 mg O3/g RPS), which allowed a sufficient delignification and facilitated the following hydrolysis step. Among all tested durations, a 4-h hydrolysis with 64% w/w sulfuric acid resulted in the highest NC production. Fluorescent staining by calcofluor white was used for simple and low-cost detection of NC in-situ. Crude NC showed a significant 63% dye uptake of 0.1 ppm acid red 131 within 30 min. Compared to the standard disposal methods of RPS, its utilization for NC production supports the circular economy concept and significantly contributes to the development of cellulose bio-based nanomaterials for water treatment applications.

Spin-Induced Organization of Cellulose Nanocrystals

Cellulose nanocrystals (CNCs) are composed of chiral cellulose units, which form chiral nematic liquid crystals in water that, upon drying, self-assemble to more complex spiral chiral sheets. This secondary structure arrangement is found to change with an external magnetic or electric field. Here, we show that one of the basic organization driving forces is electron spin, which is produced as the charge redistributes in the organization process of the chiral building blocks. It is important to stress that the electron spin-exchange interactions supply the original driving force and not the magnetic field per se. The results present the first utilization of the chiral-induced spin selectivity (CISS) effect in sugars, enabling one to regulate the CNC bottom-up fabrication process. Control is demonstrated on the organization order of the CNC by utilizing different magnetization directions of the ferromagnetic surface. The produced spin is probed using a simple Hall device. The measured Hall resistance shows that the CNC sheets' arrangement is affected during the first four hours as long as the CNC is in its wet phase. On introducing the 1,2,3,4-butanetetracarboxylic acid cross-linker into the CNC sheet, the packing density of the CNC helical structure is enhanced, presenting an increase in the Hall resistance and the chiral state.

Removal of both anionic and cationic dyes from wastewater using pH-responsive adsorbents of L-lysine molecular-grafted cellulose porous foams

High adsorption efficiency, active to both anionic and cationic dyes and simple desorption are three main challenges of the existed adsorbents for decolorization of the dye-contained wastewaters. Porous foams based on L-lysine (Lys) molecular-grafted cellulose were firstly designed and fabricated to overcome those challenges. Cellulose were grafted with Lys in 1-butyl-3-methylimidazolium chloride (BMIMCl) via a chemical connection resulted from glycidyl methacrylate (GMA). The synthesized cellulose derivative (Cell-g-PGMA-Lys) was regenerated in the morphology of foam by non-solvent induced phase inversion from the BMIMCl-based solutions. The presence of Lys moieties and porous structure of Cell-g-PGMA-Lys were confirmed with a series of instrumental analysis. Both anionic reactive brilliant red X-3B (RBR X-3B) and cationic methylene blue (MB) were effectively adsorbed on and desorbed from Cell-g-PGMA-Lys by adjusting the solution pH value. Cell-g-PGMA-Lys had higher adsorption capacities than most of the reported adsorbents and was easy to separate from the decolorized water. It could be reused many times with little reduction of the adsorption capacity, which remained 86.9% and 92.5% for RBR X-3B and MB respectively after six adsorption-desorption cycles. The isothermal and kinetic adsorption proved that dyes were adsorbed single-layered on Cell-g-PGMA-Lys depending upon the electrostatic interaction between adsorbent and adsorbate.

Novel design of bandages using cotton pads, doped with chitosan, glycogen and ZnO nanoparticles, having enhanced antimicrobial and wounds healing effects

In this present work, a new design for antimicrobial wound bandages is presented. The wound dressings were prepared using cotton fibers reinforced with elastic compression straps and secured with a polyester fabric of tight mesh size. The cotton pads were doped with a wound healing biocomposite, composed of chitosan, glycogen, and ZnO nanoparticles (CG@ZnONPs) previously formulated through a green process. The size of ZnONPs in the prepared CG@ZnONPs was 30-80 nm. The cotton pads impregnated with the CG@ZnONPs nanocomposite were characterized using FTIR, SEM, EDX, TGA, and DTGA methods. Moreover, the prepared dressings were tested on a number of intentionally injured rats. In this experiment, the % contraction of the treated wounds was monitored and compared to that of a control group of wounded rats, to which only sterile gauzes were applied. The results showed a much faster and an almost complete healing of rats treated with the synthesized dressings and the results were further confirmed by histopathological examination. The dressings were also found to exert a significant antimicrobial activity against a number of pathogenic microorganisms, generally encountered in common wounds, and could therefore be recommended to be a novel biomedical application for a fast, successful, and flawless wounds healing process.

Populus alba L., an Autochthonous Species of Spain: A Source for Cellulose Nanofibers by Chemical Pretreatment

In order to identify new sustainable sources for producing cellulose nanofibers (CNFs), fast-growing poplar (Populus alba L.) wood was evaluated herein. For that purpose, bleached poplar kraft pulp was produced and submitted to TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) mediated oxidation (TEMPO-ox) chemical pretreatment followed by microfluidization. The resulting CNFs were thoroughly characterized, including a rheological study at different pH values. Poplar CNFs showed properties comparable to eucalypt CNFs (reference material for CNFs production), showing high carboxylate content (1048 ± 128 µmol g⁻¹), fibrillation yield (87.3% ± 8.1%), optical transmittance (83% at 700 nm) and thermal stability (up to more than 200 °C). Regarding the rheological study, whereas pH from 4 to 10 did not produce significant changes in rheological behavior, a reduction of pH down to 1 led to an order-of-magnitude increase on the viscoelastic functions. Therefore, poplar CNF shows potential in the pH-sensitive hydrogels application field. Finally, the possible ecotoxicity of poplar CNF was assessed. The decrease in cell viability was very low so that only concentrations causing a 10% cytotoxicity could be calculated for the assay detecting alterations in cell metabolism (10 µg mL⁻¹) and plasma membrane integrity (60 µg mL⁻¹).

Paper-based field-effect transistor sensors

The present scenario in the world largely demands affordable, fast, recyclable, and flexible electronic devices for bio sensing. Varieties of paper-based devices such as microfluidics paper electrodes, paper diodes, and paper-based transistors etc. have been developed and validated. Most of the fabrication techniques published so far have focused on economic, environment-friendly straightforward methods to develop paper-based field-effect transistors (PFET) sensors, additionally, explored their applications. The synthetic-free, mechanically flexible, biocompatible, and signal amplification capability render PFET based sensors for wearable device makers. Modified organic/inorganic PFETs identify target analytes based on the electrical signal and endow them as perfect transducers. In the field of PFET bio sensing technology, numerous challenges are needed to be discussed to proceed forward in biomedical and other analytical applications. Realizing biologically or chemically modified PFET having an exceptional signal to noise ratio, specificity, with rapid detection ability is challenging. This review recapitulates the fabrication techniques, performances of various PFET sensors, and summarizes the report by concluding remarks including the limitations of the existing PFET based sensors and the future holds in regards to the sustainable nature of PFET.

Exploration on Structural and Optical Properties of Nanocrystalline Cellulose/Poly(3,4-Ethylenedioxythiophene) Thin Film for Potential Plasmonic Sensing Application

There are extensive studies on the development of composite solutions involving various types of materials. Therefore, this works aims to incorporate two polymers of nanocrystalline cellulose (NCC) and poly(3,4-ethylenethiophene) (PEDOT) to develop a composite thin film via the spin-coating method. Then, Fourier transform infrared (FTIR) spectroscopy is employed to confirm the functional groups of the NCC/PEDOT thin film. The atomic force microscopy (AFM) results revealed a relatively homogeneous surface with the roughness of the NCC/PEDOT thin film being slightly higher compared with individual thin films. Meanwhile, the ultraviolet/visible (UV/vis) spectrometer evaluated the optical properties of synthesized thin films, where the absorbance peaks can be observed around a wavelength of 220 to 700 nm. An optical band gap of 4.082 eV was obtained for the composite thin film, which is slightly lower as compared with a single material thin film. The NCC/PEDOT thin film was also incorporated into a plasmonic sensor based on the surface plasmon resonance principle to evaluate the potential for sensing mercury ions in an aqueous medium. Resultantly, the NCC/PEDOT thin film shows a positive response in detecting the various concentrations of mercury ions. In conclusion, this work has successfully developed a new sensing layer in fabricating an effective and potential heavy metal ions sensor.

Nanocelluloses Reinforced Bio-Waterborne Polyurethane

The aim of this work was to evaluate the influence of two kinds of bio- nano-reinforcements, cellulose nanocrystals (CNCs) and bacterial cellulose (BC), on the properties of castor oil-based waterborne polyurethane (WBPU) films. CNCs were obtained by the acidolysis of microcrystalline cellulose, while BC was produced from Komagataeibacter medellinensis. A WBPU/BC composite was prepared by the impregnation of a wet BC membrane and further drying, while the WBPU/CNC composite was obtained by casting. The nanoreinforcement was adequately dispersed in the polymer using any of the preparation methods, obtaining optically transparent compounds. Thermal gravimetric analysis, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, dynamical mechanical analysis, differential scanning calorimetry, contact angle, and water absorption tests were carried out to analyze the chemical, physical, and thermal properties, as well as the morphology of nanocelluloses and composites. The incorporation of nanoreinforcements into the formulation increased the storage modulus above the glass transition temperature of the polymer. The thermal stability of the BC-reinforced composites was slightly higher than that of the CNC composites. In addition, BC allowed maintaining the structural integrity of the composites films, when they were immersed in water. The results were related to the relatively high thermal stability and the particular three-dimensional interconnected reticular morphology of BC.

Cellulose-Based Flexible Functional Materials for Emerging Intelligent Electronics

There is currently enormous and growing demand for flexible electronics for personalized mobile equipment, human-machine interface units, wearable medical-healthcare systems, and bionic intelligent robots. Cellulose is a well-known natural biopolymer that has multiple advantages including low cost, renewability, easy processability, and biodegradability, as well as appealing mechanical performance, dielectricity, piezoelectricity, and convertibility. Because of its multiple merits, cellulose is frequently used as a substrate, binder, dielectric layer, gel electrolyte, and derived carbon material for flexible electronic devices. Leveraging the advantages of cellulose to design advanced functional materials will have a significant impact on portable intelligent electronics. Herein, the unique molecular structure and nanostructures (nanocrystals, nanofibers, nanosheets, etc.) of cellulose are briefly introduced, the structure-property-application relationships of cellulosic materials summarized, and the processing technologies for fabricating cellulose-based flexible electronics considered. The focus then turns to the recent advances of cellulose-based functional materials toward emerging intelligent electronic devices including flexible sensors, optoelectronic devices, field-effect transistors, nanogenerators, electrochemical energy storage devices, biomimetic electronic skins, and biological detection devices. Finally, an outlook of the potential challenges and future prospects for developing cellulose-based wearable devices and bioelectronic systems is presented.

Removal of Methylene Blue Dye from Wastewater Using Periodiated Modified Nanocellulose

The study was focused on the preparation and characterizations of sodium periodate-modified nanocellulose (NaIO4-NC) prepared from Eichhornia crassipes for the removal of cationic methylene blue (MB) dye from wastewater (WW). A chemical method was used for the preparation of NaIO4-NC. The prepared NaIO4-NC adsorbent was characterized by using X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM), energy-dispersive X-ray (EDX), and Brunauer–Emmett–Teller (BET) instruments. Next, it was tested to the adsorption of MB dye from WW using batch experiments. The adsorption process was performed using Langmuir and Freundlich isotherm models with maximum adsorption efficiency (qmax) of 90.91 mg·g−1 and percent color removal of 78.1% at optimum 30 mg·L−1, 60 min., 1 g, and 8 values of initial concentration, contact time, adsorbent dose, and solution pH, respectively. Pseudo-second-order (PSO) kinetic model was well fitted for the adsorption of MB dye through the chemisorption process. The adsorption process was spontaneous and feasible from the thermodynamic study because the Gibbs free energy value was negative. After adsorption, the decreased values for physicochemical parameters of WW were observed in addition to the color removal. From the regeneration study, it is possible to conclude that NaIO4-NC adsorbent was recyclable and reused as MB dye adsorption for 13 successive cycles without significant efficient loss.

Ionic Conductive Cellulose Mats by Solution Blow Spinning as Substrate and a Dielectric Interstrate Layer for Flexible Electronics

Renewable cellulose substrates with submicron- and nanoscale structures have revived interest in paper electronics. However, the processes behind their production are still complex and time- and energy-consuming. Besides, the weak electrolytic properties of cellulose with submicron- and nanoscale structures have hindered its application in transistors and integrated circuits with low-voltage operation. Here, we report a simple, low-cost approach to produce flexible ionic conductive cellulose mats using solution blow spinning, which are used both as dielectric interstrate and substrate in low-voltage devices. The electrochemical properties of the cellulose mats are tuned through infiltration with alkali hydroxides (LiOH, NaOH, or KOH), enabling their application as dielectric and substrate in flexible, low-voltage, oxide-based field-effect transistors and pencil-drawn resistor-loaded inverters. The transistors exhibit good transistor performances under operation voltage below 2.5 V, and their electrical performance is strictly related to the type of alkali ionic specie incorporated. Devices fabricated on K⁺-infiltrated cellulose mats present the best characteristics, indicating pure capacitive charging of the semiconductor. The pencil-drawn load resistor inverter presents good dynamic performance. These findings may pave the way for a new generation of low-power, wearable electronics, enabling concepts such as the "Internet of Things".

What Is Driving the Growth of Inorganic Glass in Smart Materials and Opto-Electronic Devices?

Inorganic glass is a transparent functional material and one of the few materials that keeps leading innovation. In the last decades, inorganic glass was integrated into opto-electronic devices such as optical fibers, semiconductors, solar cells, transparent photovoltaic devices, or photonic crystals and in smart materials applications such as environmental, pharmaceutical, and medical sensors, reinforcing its influence as an essential material and providing potential growth opportunities for the market. Moreover, inorganic glass is the only material that is 100% recyclable and can incorporate other industrial offscourings and/or residues to be used as raw materials. Over time, inorganic glass experienced an extensive range of fabrication techniques, from traditional melting-quenching (with an immense diversity of protocols) to chemical vapor deposition (CVD), physical vapor deposition (PVD), and wet chemistry routes as sol-gel and solvothermal processes. Additive manufacturing (AM) was recently added to the list. Bulks (3D), thin/thick films (2D), flexible glass (2D), powders (2D), fibers (1D), and nanoparticles (NPs) (0D) are examples of possible inorganic glass architectures able to integrate smart materials and opto-electronic devices, leading to added-value products in a wide range of markets. In this review, selected examples of inorganic glasses in areas such as: (i) magnetic glass materials, (ii) solar cells and transparent photovoltaic devices, (iii) photonic crystal, and (iv) smart materials are presented and discussed.

Metal Oxide-Based Photocatalytic Paper: A Green Alternative for Environmental Remediation

The interest in advanced photocatalytic technologies with metal oxide-based nanomaterials has been growing exponentially over the years due to their green and sustainable characteristics. Photocatalysis has been employed in several applications ranging from the degradation of pollutants to water splitting, CO2 and N2 reductions, and microorganism inactivation. However, to maintain its eco-friendly aspect, new solutions must be identified to ensure sustainability. One alternative is creating an enhanced photocatalytic paper by introducing cellulose-based materials to the process. Paper can participate as a substrate for the metal oxides, but it can also form composites or membranes, and it adds a valuable contribution as it is environmentally friendly, low-cost, flexible, recyclable, lightweight, and earth abundant. In term of photocatalysts, the use of metal oxides is widely spread, mostly since these materials display enhanced photocatalytic activities, allied to their chemical stability, non-toxicity, and earth abundance, despite being inexpensive and compatible with low-cost wet-chemical synthesis routes. This manuscript extensively reviews the recent developments of using photocatalytic papers with nanostructured metal oxides for environmental remediation. It focuses on titanium dioxide (TiO2) and zinc oxide (ZnO) in the form of nanostructures or thin films. It discusses the main characteristics of metal oxides and correlates them to their photocatalytic activity. The role of cellulose-based materials on the systems’ photocatalytic performance is extensively discussed, and the future perspective for photocatalytic papers is highlighted.

Printable and recyclable carbon electronics using crystalline nanocellulose dielectrics

Electronic waste can lead to the accumulation of environmentally and biologically toxic materials and is a growing global concern. Developments in transient electronics-in which devices are designed to disintegrate after use-have focused on increasing the biocompatibility, whereas efforts to develop methods to recapture and reuse materials have focused on conducting materials, while neglecting other electronic materials. Here, we report all-carbon thin-film transistors made using crystalline nanocellulose as a dielectric, carbon nanotubes as a semiconductor, graphene as a conductor and paper as a substrate. A crystalline nanocellulose ink is developed that is compatible with nanotube and graphene inks and can be written onto a paper substrate using room-temperature aerosol jet printing. The addition of mobile sodium ions to the dielectric improves the thin-film transistor on-current (87 μA mm^-1) and subthreshold swing (132 mV dec^-1), and leads to a faster voltage sweep rate (by around 20 times) than without ions. The devices also exhibit stable performance over six months in ambient conditions and can be controllably decomposed, with the graphene and carbon nanotube inks recaptured for recycling (>95% recapture efficiency) and reprinting of new transistors. We demonstrate the utility of the thin-film transistors by creating a fully printed, paper-based biosensor for lactate sensing.

Sustainable green strategy for recovery of glucose from end-of-life euro banknotes

Usually, Euro banknotes are made from cotton substrates and their waste is disposed of in landfill or is incinerated. In order to valorize the end-of-life euro banknotes (ELEBs), the substrates were used in this research for cellulase production via submerged fungal fermentation (SFF), and the resultant fungal cellulase w s used in ELEBs hydrolysis process for extraction of glucose. The experiments were started by exposing the ELEBs to different types of pretreatments, including milling process, alkali (NaOH/urea solution), and acid leaching to remove any contamination (e.g. dyes) and to decrease the crystallinity of cellulose (the main element in cotton substrate) thus increasing the degradation rate during the fermentation process. The effect of pretreatments on the morphology and chemical composition of ELEBs was observed using Scanning Electron Microscope and Energy Dispersive Spectrometry. Afterwards, Trichoderma reesei-DSM76 was used for cellulase production from the treated ELEBs with high cellulase activity (12.97 FPU/g). The resultant cellulase was upscaled in a bioreactor and used in ELEBs hydrolysis. Finally, the results showed that the optimized pretreatment methods (milling followed by leaching process) significantly improved the cellulase activity and glucose recovery, which was estimated by 96%. According to the obtained results, the developed strategy has a great potential for conversion of ELEBs into a glucose product that could be used in biofuels and bioplastics applications.

Unveiling Modifications of Biomass Polysaccharides during Thermal Treatment in Cholinium Chloride : Lactic Acid Deep Eutectic Solvent

A deep analysis upon the chemical modifications of the cellulose and hemicelluloses fractions that take place during biomass delignification with deep eutectic solvents (DES) is lacking in literature, being this a critical issue given the continued research on DES for this purpose. This work intends to fill this gap by disclosing a comprehensive study on the chemical modifications of cellulose (microcrystalline cellulose and bleached kraft pulp) and hemicelluloses (xylans) during thermal treatment (130 °C) with cholinium chloride/lactic acid ([Ch]Cl/LA) at molar ratio 1 : 10, one of the best reported DES for biomass delignification. The obtained data revealed that [Ch]Cl/LA (1 : 10) has a negative impact on the polysaccharides fractions at prolonged treatments (>4 h), resulting on substantial modifications including the esterification of cellulose with lactic acid, shortening of fibers length, fibers agglomeration and side reactions of the hemicelluloses fraction (e. g., humin formation, lactic acid grafting). Wood delignification trials with [Ch]Cl/LA (1 : 10) at the same conditions also corroborate these findings. Moreover, the DES suffers degradation, including the formation of lactic acid derivatives and its polymerization. Therefore, short time delignification treatments are strongly recommended when using the [Ch]Cl/LA DES, so that a sustainable fractionation of biomass into high quality cellulose fibers, isolated lignin, and xylose/furfural co-production along with solvent recyclability could be achieved.

Biodegradable Materials for Sustainable Health Monitoring Devices

The recent advent of biodegradable materials has offered huge opportunity to transform healthcare technologies by enabling sensors that degrade naturally after use. The implantable electronic systems made from such materials eliminate the need for extraction or reoperation, minimize chronic inflammatory responses, and hence offer attractive propositions for future biomedical technology. The eco-friendly sensor systems developed from degradable materials could also help mitigate some of the major environmental issues by reducing the volume of electronic or medical waste produced and, in turn, the carbon footprint. With this background, herein we present a comprehensive overview of the structural and functional biodegradable materials that have been used for various biodegradable or bioresorbable electronic devices. The discussion focuses on the dissolution rates and degradation mechanisms of materials such as natural and synthetic polymers, organic or inorganic semiconductors, and hydrolyzable metals. The recent trend and examples of biodegradable or bioresorbable materials-based sensors for body monitoring, diagnostic, and medical therapeutic applications are also presented. Lastly, key technological challenges are discussed for clinical application of biodegradable sensors, particularly for implantable devices with wireless data and power transfer. Promising perspectives for the advancement of future generation of biodegradable sensor systems are also presented.

Synthesis of cellulose nanocrystals (CNCs) from cotton using ultrasound-assisted acid hydrolysis

This present work reports the synthesis of Cellulose nanocrystals (CNCs) from cotton using an ultrasound-assisted acid hydrolysis. Further, the synthesized CNCs was comprehensively characterized using Fourier Transform Infrared Spectroscopy (FTIR) to analyze surface functional groups and X-ray diffraction (XRD) in studying structural characteristics. Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA) have been used to study the thermal properties of CNCs. Morphology of CNCs was studied using a Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM). The crystallite size was found to be 10-50 nm using XRD data and the average particle size to be 221 nm using PSD analysis.

Environmentally friendly superabsorbent fibers based on electrospun cellulose nanofibers extracted from wheat straw

Superabsorbent polymers currently used in health and agricultural sectors are based on petroleum-based materials which led to serious concerns in the society. Here, superabsorbent fibers (SAFs) based on electrospun cellulose nanofibers (ECNFs) were prepared. Firstly, cellulose was removed from wheat straw, pre-treated with the TEMPO-mediated oxidation and subsequently dissolved into Trifluoroacetic acid for production of ECNFs through the electrospinning approach. The maximum swelling ratios of 225 g/g and 208 g/g in distilled water and 0.9 wt% NaCl solution were measured for ESAFs composed of oxidized ECNFs containing 15 % poly (sodium acrylate), respectively. The ESAFs were characterized using Fourier transform infrared spectroscopy and field emission scanning electron microscopy analysis. The FESEM showed that ESAFs formed high strength three-dimensional architecture networks. Also, the results showed that the ionic sensitivity of this ECNFs were low. The prepared ESAFs are attractive renewable alternatives for different applications, contributing to a reduction of plastic microspheres.

Novel buffalo rumen metagenome derived acidic cellulase Cel-3.1 cloning, characterization, and its application in saccharifying rice straw and corncob biomass

Lignocellulosic biomass (LCB) is a prominent option for second-generation biofuels production. Cellulase hydrolyses cellulose, a component of LCB by attacking the β-1,4-glycosidic bonds, thus liberating mono, di, and oligosaccharides, which subsequently, can be converted to biofuel. In this study, a novel cellulase (Cel-3.1) of 1593 bp which encodes a 530 amino acid protein was identified from buffalo rumen metagenomic fosmid library, and functional expression was achieved through transformation into Escherichia coli. The molecular weight was estimated as 58 kDa on SDS-PAGE. Cel-3.1 belongs to glycosyl hydrolase family-5 (GH-5) and is predicted to have 14 α-helices and 15 β-strands. The optimal temperature and pH for Cel-3.1 were experimentally determined as 5.0 and 50 °C respectively. The synergistic effect of Ca²⁺ with K⁺ ions improved Cel-3.1 activity significantly (25%) and 1% Polyethylene Glycol (PEG-400), 1% β-mercaptoethanol enhanced the relative activity Cel-3.1 by 31.68%, 12.03% respectively. Further, the enzymatic (Cel-3.1) hydrolysis of pretreated rice straw and corncob released 13.41 ± 0.26 mg/mL and 15.04 ± 0.08 mg/mL reducing sugars respectively. High Performance Liquid Chromatography (HPLC), Scanning Electron Microscope (SEM), and Fourier Transformation Infrared spectroscopy (FTIR) analysis revealed the capability of Cel-3.1 for the breakdown and hydrolysis of both rice straw and corncob to generate various fermentable sugars.

Synthesis, Characterization and Cytotoxicity Studies of Aminated Microcrystalline Cellulose Derivatives against Melanoma and Breast Cancer Cell Lines

Cellulose based materials are emerging in the commercial fields and high-end applications, especially in biomedicines. Aminated cellulose derivatives have been extensively used for various applications but limited data are available regarding its cytotoxicity studies for biomedical application. The aim of this study is to synthesize different 6-deoxy-amino-cellulose derivatives from Microcrystalline cellulose (MCC) via tosylation and explore their cytotoxic potential against normal fibroblasts, melanoma and breast cancer. 6-deoxy-6-hydrazide Cellulose (Cell Hyd) 6-deoxy-6-diethylamide Cellulose (Cell DEA) and 6-deoxy-6-diethyltriamine Cellulose (Cell DETA) were prepared and characterized by various technologies like Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), nuclear magnetic resonance spectroscopy (NMR), X-ray diffractogram (XRD), Scanning Electron microscopy (SEM), Elemental Analysis and Zeta potential measurements. Cytotoxicity was evaluated against normal fibroblasts (NIH3T3), mouse skin melanoma (B16F10), human epithelial adenocarcinoma (MDA-MB-231) and human breast adenocarcinoma (MCF-7) cell lines. IC₅₀ values obtained from cytotoxicity assay and live/dead assay images analysis showed MCC was non cytotoxic while Cell Hyd, Cell DEA and Cell DETA exhibited noncytotoxic activity up to 200 μg/mL to normal fibroblast cells NIH3T3, suggesting its safe use in medical fields. The mouse skin melanoma (B16F10) are the most sensitive cells to the cytotoxic effects of Cell Hyd, Cell DEA and Cell DETA, followed by human breast adenocarcinoma (MCF-7). Based on our study, it is suggested that aminated cellulose derivatives could be promising candidates for tissue engineering applications and in cancer inhibiting studies in future.

Sensors Made of Natural Renewable Materials: Efficiency, Recyclability or Biodegradability-The Green Electronics

Nowadays, sensor devices are developing fast. It is therefore critical, at a time when the availability and recyclability of materials are, along with acceptability from the consumers, among the most important criteria used by industrials before pushing a device to market, to review the most recent advances related to functional electronic materials, substrates or packaging materials with natural origins and/or presenting good recyclability. This review proposes, in the first section, passive materials used as substrates, supporting matrixes or packaging, whether organic or inorganic, then active materials such as conductors or semiconductors. The last section is dedicated to the review of pertinent sensors and devices integrated in sensors, along with their fabrication methods.

Nature-derived materials for the fabrication of functional biodevices

Nature provides an incredible source of inspiration, structural concepts, and materials toward applications to improve the lives of people around the world, while preserving ecosystems, and addressing environmental sustainability. In particular, materials derived from animal and plant sources can provide low-cost, renewable building blocks for such applications. Nature-derived materials are of interest for their properties of biodegradability, bioconformability, biorecognition, self-repair, and stimuli response. While long used in tissue engineering and regenerative medicine, their use in functional devices such as (bio)electronics, sensors, and optical systems for healthcare and biomonitoring is finding increasing attention. The objective of this review is to cover the varied nature derived and sourced materials currently used in active biodevices and components that possess electrical or electronic behavior. We discuss materials ranging from proteins and polypeptides such as silk and collagen, polysaccharides including chitin and cellulose, to seaweed derived biomaterials, and DNA. These materials may be used as passive substrates or support architectures and often, as the functional elements either by themselves or as biocomposites. We further discuss natural pigments such as melanin and indigo that serve as active elements in devices. Increasingly, combinations of different biomaterials are being used to address the challenges of fabrication and performance in human monitoring or medicine. Finally, this review gives perspectives on the sourcing, processing, degradation, and biocompatibility of these materials. This rapidly growing multidisciplinary area of research will be advanced by a systematic understanding of nature-inspired materials and design concepts in (bio)electronic devices.

Flexible and Structural Coloured Composite Films from Cellulose Nanocrystals/Hydroxypropyl Cellulose Lyotropic Suspensions

Lyotropic colloidal aqueous suspensions of cellulose nanocrystals (CNCs) can, after solvent evaporation, retain their chiral nematic arrangement. As water is removed the pitch value of the suspension decreases and structural colour-generating films, which are mechanically brittle in nature, can be obtained. Increasing their flexibility while keeping the chiral nematic structure and biocompatible nature is a challenging task. However, if achievable, this will promote their use in new and interesting applications. In this study, we report on the addition of different amounts of hydroxypropyl cellulose (HPC) to CNCs suspension within the coexistence of the isotropic-anisotropic phases and infer the influence of this cellulosic derivative on the properties of the obtained solid films. It was possible to add 50 wt.% of HPC to a CNCs aqueous suspension (to obtain a 50/50 solids ratio) without disrupting the LC phase of CNCs and maintaining a left-handed helical structure in the obtained films. When 30 wt.% of HPC was added to the suspension of CNCs, a strong colouration in the film was still observed. This colour shifts to the near-infrared region as the HPC content in the colloidal suspension increases to 40 wt.% or 50 wt.% The all-cellulosic composite films present an increase in the maximum strain as the concentration of HPC increases, as shown by the bending experiments and an improvement in their thermal properties.

A superhydrophilic bilayer structure of a nylon 6 nanofiber/cellulose membrane and its characterization as potential water filtration media

A bilayer structure of a nylon 6 nanofibrous membrane on a cellulose membrane has been successfully developed for water filter application. The nylon 6 nanofibrous membrane was deposited on the cellulose membrane via the electrospinning technique. The bilayer membrane properties, including mechanical strength, wettability, porosity, and microfiltration performance (flux and rejection), were thoroughly investigated. The membrane properties were studied using nylon 6 nanofibrous membranes having various fiber diameters and membrane thicknesses, which were obtained by adjusting the solution concentration and spinning time. The measurement of solution parameters, i.e., viscosity, conductivity, and surface tension, showed a strong relationship between the solution concentration and these parameters, which later changed the fabricated fiber sizes. The FTIR spectra depicted complete solvent evaporation after the electrospinning process. Smaller nanofiber diameters could improve the mechanical strength of the membranes. The porosity test showed a strong relationship between the nanofiber diameter and the pore size and pore distribution of the membranes. The water contact angle measurement showed the significant influence of the cellulose membrane on increasing the hydrophilicity of the bilayer structure, which then improved the membrane flux. The particle rejection test, using PSL sizes of 308 and 450 nm, showed high rejection (above 98%) for all sample thickness variations. Overall, the bilayer structure of the nylon 6 nanofibers/cellulose membranes showed excellent and promising performance as water filter media.

The SEM image of (a) cellulose membrane and (b) the bilayer structure of a nylon 6 nanofibrous membrane on a cellulose membrane as water filter media.

Assessment of microplastic pollution: occurrence and characterisation in Vesijärvi lake and Pikku Vesijärvi pond, Finland

In the last few years, several studies have investigated microplastics (MPs) in marine ecosystems, but data monitoring and assessing the occurrence in freshwater environments are still scarce. The present study aims to investigate the occurrence, distribution, and chemical composition of MP pollution in Vesijärvi lake and Pikku Vesijärvi pond close to the city of Lahti (Finland) in winter. Sediment, snow, and ice core samples were collected near the shore of these two aquatic systems. MPs were analysed and identified by a non-destructive method using Fourier transform infrared spectroscopy (FTIR) 2D imaging. The mean concentrations of MPs detected in sediment, snow, and ice samples were 395.5 ± 90.7 MPs/kg, 117.1 ± 18.4 MPs/L, and 7.8 ± 1.2 MPs/L, respectively. FTIR results showed the predominant abundance of microplastics, such as polyamides (up to 53.3%), polyethylene and polypropylene (up to 17.1%), and natural fragments such as cellulose (up to 45.8%) and wool (up 18.8%) in the same size range. The potential release of MPs arising from stormwaters and sport and recreational activities was evidenced.

Disposable electrodes from waste materials and renewable sources for (bio)electroanalytical applications

The numerous advantages of disposable and screen-printed electrodes (SPEs) particularly in terms of portability, sensibility, sensitivity and low-cost led to the massive application of these electroanalytical devices. To limit the electronic waste and recover precious materials, new recycling processes were developed together with alternative SPEs fabrication procedures based on renewable, biocompatible sources or waste materials, such as paper, agricultural byproducts or spent batteries. The increased interest in the use of eco-friendly materials for electronics has given rise to a new generation of highly performing green modifiers. From paper based electrodes to disposable electrodes obtained from CD/DVD, in the last decades considerable efforts were devoted to reuse and recycle in the field of electrochemistry. Here an overview of recycled and recyclable disposable electrodes, sustainable electrode modifiers and alternative fabrication processes is proposed aiming to provide meaningful examples to redesign the world of disposable electrodes.

Potential of di-aldehyde cellulose for sustained release of oxytetracycline: A pharmacokinetic study

This study focused on the in-vivo sustained release of oxytetracycline (OTC) loaded on di-aldehyde cellulose (DAC). The periodate oxidation method was used for the synthesis of DAC. The prepared DAC-OTC material was characterized by different techniques such as Scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Transmission electron microscopy (TEM) and particle size analyzer. The pharmacokinetic studies were performed on DAC-OTC composite system and commercial tablet (COTA). The results of pharmacokinetic studies demonstrated that DAC-OTC exhibited higher area under the curve (AUC) (482.8 μghmL^-1) as compared to COTA (90.72 μghmL^-1). DAC-OTC composite system has double compartment pattern with improvement in mean residing time (MRT) and area under moment curve (AUMC_0-∞) than the commercial tablet (2.8 and 15.13 folds higher, respectively). Swelling index of DAC-OTC at different pH and pKa of OTC release imply that controlled in-vivo release in DAC-OTC composite system could be due to the simultaneous occurrence of the covalent and hydrogen bond between OTC and di-aldehyde cellulose. These results indicate that di-aldehyde cellulose may improve the in-vivo bioavailability of OTC.