Preparation and characterization of cellulose nanowhiskers from cotton fibres by controlled microbial hydrolysis

Effect of Hydrochloric Acid Hydrolysis under Sonication and Hydrothermal Process to Produce Cellulose Nanocrystals from Oil Palm Empty Fruit Bunch (OPEFB)

This paper presents an approach for hydrolyzing cellulose nanocrystals from oil palm empty fruit bunch (OPEFB) presented through hydrochloric acid hydrolysis under sonication-hydrothermal conditions. Differences in concentration, reaction time, and acid-to-cellulose ratio affect toward the yield, crystallinity, microstructure, and thermal stability were obtained. The highest yield of cellulose nanocrystals up to 74.82%, crystallinity up to 78.59%, and a maximum degradation temperature (Tmax) of 339.82 °C were achieved through hydrolysis using 3 M HCl at 110 °C during 1 h. X-ray diffraction analysis indicated a higher diffraction peak pattern at 2θ = 22.6° and a low diffraction peak pattern at 2θ = 18°. All cellulose nanocrystals showed a crystalline size of under 1 nm, and it was indicated that the sonication-hydrothermal process could reduce the crystalline size of cellulose. Infrared spectroscopy analysis showed that a deletion of lignin and hemicellulose was demonstrated in the spectrum. Cellulose nanocrystal morphology showed a more compact structure and well-ordered surface arrangement than cellulose. Cellulose nanocrystals also had good thermal stability, as a high maximum degradation temperature was indicated, where CNC-D1 began degrading at temperatures (T0) of 307.09 °C and decomposed (Tmax) at 340.56 °C.

Physico-chemical and antifungal studies of spun cotton thread reinforced cellulose film

This study examines cellulose films reinforced with spun cotton thread and their antifungal properties. The morphology and structure of the cellulose film are analyzed using various techniques, including X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) Spectroscopy, Field Emission Scanning Electron Microscope (FE-SEM), Atomic Force Microscope (AFM), UV-Visible Spectroscopy (UV-Vis), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC). The XRD pattern confirms the crystalline nature of the spun cotton-reinforced cellulose film. UV absorption analysis shows activity in the UV region of the optical spectrum. The reinforced cellulose film shows a band gap of 4.7 eV by employing the Wood and Tauc equation. FTIR spectroscopy confirms the film's structural formation. Morphological analysis reveals a random distribution of numerous pore structures on the material's surface. Thermalgravimetric Analysis indicates the material's stability at elevated temperatures, suggesting versatile applications. The film also exhibits antifungal activity against Candida albicans. This research highlights the potential of reinforced cellulose film in various applications, such as food and non-food packaging, offering enhanced UV protection and strength for heavy goods transport. The study emphasizes the multifunctional properties of the material, showcasing its promising role as a polymer in various practical applications.

Brown sugar as a carbon source can make agricultural organic waste compost enter the secondary thermophilic stage and promote compost decomposition

To enhance the efficiency of composting agricultural organic waste (AOW), this study aimed to examine the impact of inoculating tomato straw compost with two distinct microbial agents: ZymoZone (ZZ), a composite microbial agent derived from the straw compost and Effective Microorganisms (EM), a commercial microbial agent. Furthermore, in order to reactivate the microorganisms within the compost during the initial high temperature phase, 10% brown sugar was introduced as a carbon source. The objective of this addition was to assess its influence on the composting process. The findings revealed that compared to the control (CK) group, the ZZ and EM treatments extended the first high-temperature phase by 2 and 1 day, respectively. Furthermore, with the addition of 10% brown sugar, the ZZ and EM treatments remained in the second high-temperature phase for 8 and 7 days, respectively, while the CK treatment had already entered the cooling stage by then. Notably, the inoculation of microbial agents and the addition of brown sugar substantially augmented the activity of lignocellulose-related hydrolases, thereby promoting the degradation of lignocellulose in the ZZ and EM treatment groups. This was confirmed by FTIR analysis, which demonstrated that the addition of microbial agents facilitated the degradation of specific substances, leading to reduced absorbance in the corresponding spectra. XRD analysis further indicated a notable reduction in cellulose crystallinity for both the ZZ (8.00%) and EM (7.73%) treatments. Hence, the incorporation of microbial agents and brown sugar in tomato straw compost effectively enhances the composting process and improves the quality of compost products.

Nanocellulose: A comprehensive review investigating its potential as an innovative material for water remediation

Rapid growth in industrialization sectors, the wastewater treatment plants become exhausted and potentially not able to give desirable discharge standards. Many industries discharge the untreated effluent into the water bodies which affects the aquatic diversity and human health. The effective disposal of industrial effluents thus has been an imperative requirement. For decades nanocellulose based materials gained immense attraction towards application in wastewater remediation and emerged out as a new biobased nanomaterial. It is light weighted, cost effective, mechanically strong and easily available. Large surface area, versatile surface functionality, biodegradability, high aspect ratio etc., make them suitable candidate in this field. Majorly cellulose based nanomaterials are used in the form of cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), or bacterial nanocellulose (BNC). This review specifically describes about a variety of extraction methods to produced nanocellulose and also discusses the modification of nanocellulose by adding functionalities in its surface chemistry. We majorly focus on the utilization of nanocellulose based materials in water remediation for the removal of different contaminants such as dyes, heavy metals, oil, microbial colony etc. This review mainly emphasizes in ray of hope towards nanocellulose materials to achieve more advancement in the water remediation fields.

Insight into the Latest Medical Applications of Nanocellulose

Nanocelluloses (NCs) are appealing nanomaterials that have experienced rapid development in recent years, with great potential in the biomedical field. This trend aligns with the increasing demand for sustainable materials, which will contribute both to an improvement in wellbeing and an extension of human life, and with the demand to keep up with advances in medical technology. In recent years, due to the diversity of their physical and biological properties and the possibility of tuning them according to the desired goal, these nanomaterials represent a point of maximum interest in the medical field. Applications such as tissue engineering, drug delivery, wound dressing, medical implants or those in cardiovascular health are some of the applications in which NCs have been successfully used. This review presents insight into the latest medical applications of NCs, in the forms of cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs) and bacterial nanocellulose (BNC), with an emphasis on the domains that have recently experienced remarkable growth, namely wound dressing, tissue engineering and drug delivery. In order to highlight only the most recent achievements, the presented information is focused on studies from the last 3 years. Approaches to the preparation of NCs are discussed either by top-down (chemical or mechanical degradation) or by bottom-up (biosynthesis) techniques, along with their morphological characterization and unique properties, such as mechanical and biological properties. Finally, the main challenges, limitations and future research directions of NCs are identified in a sustained effort to identify their effective use in biomedical fields.

Experimental and Modeling Optimization of Strontium Adsorption on Microbial Nanocellulose, Eco-friendly Approach

Green synthesized cellulose nanocrystals (CNCs) was prepared using Neurospora intermedia, characterized, and used to remove Strontium ions (Sr2+) from an aqueous solution with high efficiency. The characterization of CNCs was performed using a UV-Vis Spectrophotometer, Dynamic Light Scattering (DLS), Zeta Potential (ZP), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) mapping, EDX elemental analysis and BET surface analyzer. In this study, Response Surface Methodology (RSM) based on Box-Behnken Design (BBD) was successfully applied for the first time to optimize the dynamic adsorption conditions for the maximum removal of Sr2+ ions from aqueous solutions using CNCs as adsorbent. The effects of parameters, such as initial concentration of Sr2+ (50–500 ppm), adsorbent dosage (0.05–0.2 g/50ml), and contact time (15–120 min.) on removal efficiency were investigated. A mathematical model was studied to predict the removal performance. The significance and adequacy of the model were surveyed using the analysis of variance (ANOVA). The results showed that the second-order polynomial model is suitable for the prediction removal of Sr2+ with regression coefficient (R2 = 97.41%). The highest sorption capacity value of Sr2+ was obtained (281.89 mg/g) at the adsorbent dosage of 0.05 g/50 ml, contact time of 120 min., and the pollutant (Sr2+) concentration of 275 ppm.

Tailoring Functionality of Nanocellulose: Current Status and Critical Challenges

Nanocellulose (NC) isolated from natural cellulose resources, which mainly includes cellulose nanofibril (CNF) and cellulose nanocrystal (CNC), has garnered increased attention in recent decades due to its outstanding physical and chemical properties. Various chemical modifications have been developed with the aim of surface-modifying NC for highly sophisticated applications. This review comprehensively summarizes the chemical modifications applied to NC so far in order to introduce new functionalities to the material, such as silanization, esterification, oxidation, etherification, grafting, coating, and others. The new functionalities obtained through such surface-modification methods include hydrophobicity, conductivity, antibacterial properties, and absorbability. In addition, the incorporation of NC in some functional materials, such as films, wearable sensors, cellulose nanospheres, aerogel, hydrogels, and nanocomposites, is discussed in relation to the tailoring of the functionality of NC. It should be pointed out that some issues need to be addressed during the preparation of NC and NC-based materials, such as the low reactivity of these raw materials, the difficulties involved in their scale-up, and their high energy and water consumption. Over the past decades, some methods have been developed, such as the use of pretreatment methods, the adaptation of low-cost starting raw materials, and the use of environmentally friendly chemicals, which support the practical application of NC and NC-based materials. Overall, it is believed that as a green, sustainable, and renewable nanomaterial, NC is will be suitable for large-scale applications in the future.

Preparation of microcrystalline cellulose from agricultural residues and their application as polylactic acid/microcrystalline cellulose composite films for the preservation of Lanzhou lily

Microcrystalline celluloses were isolated from four agricultural residues, including sweet sorghum stalk, Jerusalem artichoke stalk, grains stillage, and Chinese herb residue, and characterized in terms of physicochemical and structural properties. The obtained microcrystalline celluloses were composited with polylactic acid as a packing film for the preservation of Lanzhou lily. All the agricultural residues-derived microcrystalline celluloses were in cellulose I_β structure with high purity and good thermal stability. Microcrystalline celluloses from sweet sorghum stalk had a higher degree of polymerization (327) and crystallinity (70.52 %) than others. The preservation effect of lily bulbs packaged by films were significantly improved indicated by the lessened weight loss rate and the meliorative hardness and whiteness, which ascribe to the repressed oxidation reactions. Polylactic acid/microcrystalline cellulose composite films prepared from sweet sorghum straw have been proved the most effective. This work could offer a value-added outlet for agricultural residues to produce microcrystalline celluloses-based biocompatible films for preservation of Lanzhou lily.

Effect of ultrasound on the physical properties and processing of major biopolymers-a review

Designing and developing modern techniques to facilitate the extraction and modification of functional properties of biopolymers are key motivations among researchers. As a low-cost, sustainable, non-toxic, and fast process, ultrasound has been considered a method to improve the processing of carbohydrate and protein-based biopolymers such as cellulose, chitin, starch, alginate, carrageenan, gelatine, and guar gum. A better understanding of the complex physicochemical behavior of biopolymers under ultrasonication may fortify the eminence of this technology in advanced-level applications. This review summarizes the recent advances in biopolymer processing and the effect of ultrasound on the physical properties of the selected biopolymers. A major focus will be given to the mechanisms of action and their impact on the properties and extraction. At the end, some possible suggestions are highlighted which need future investigation for amending the physical properties of biopolymers using ultrasonication.

Ultrasonic cavitation: An effective cleaner and greener intensification technology in the extraction and surface modification of nanocellulose

With rising consumer demand for natural products, a greener and cleaner technology, i.e., ultrasound-assisted extraction, has received immense attention given its effective and rapid isolation for nanocellulose compared to conventional methods. Nevertheless, the application of ultrasound on a commercial scale is limited due to the challenges associated with process optimization, high energy requirement, difficulty in equipment design and process scale-up, safety and regulatory issues. This review aims to narrow the research gap by placing the current research activities into perspectives and highlighting the diversified applications, significant roles, and potentials of ultrasound to ease future developments. In recent years, enhancements have been reported with ultrasound assistance, including a reduction in extraction duration, minimization of the reliance on harmful chemicals, and, most importantly, improved yield and properties of nanocellulose. An extensive review of the strengths and weaknesses of ultrasound-assisted treatments has also been considered. Essentially, the cavitation phenomena enhance the extraction efficiency through an increased mass transfer rate between the substrate and solvent due to the implosion of microbubbles. Optimization of process parameters such as ultrasonic intensity, duration, and frequency have indicated their significance for improved efficiency.

Valuable aramid/cellulose nanofibers derived from recycled resources for reinforcing carbon fiber/phenolic composites

The scale-up preparation of aramid nanofiber (ANF) and cellulose nanofiber (CNF), still faces serious challenges such as extreme production cost and lengthy preparation cycle. Herein, a feasible top-down strategy was proposed to achieve the efficient reclamation of waste resources, further realizing the large-scale production of high value-added nanofibers. The ANF/CNF as nanoscale building blocks and their reinforcement effects on the mechanical performances of carbon fiber/phenolic composites were investigated. Related strength and modulus of ANF/CNF-enhanced composites in the tensile, bending, shear and nano indentation tests, increased by 118.1% (tensile strength), 141.2% (tensile modulus), 142.2% (flexural strength), 354.4% (flexural modulus), 38.8% (shear strength) and 94.4% (elastic modulus), respectively. Our work offers a valuable reference in the fabrication of low-cost ANF/CNF derived from waste resources, which would facilitate the wide application of nanofibers in fabricating high-performance advanced functional materials.

Effective extraction of fluoroquinolones from water using facile modified plant fibers

In this study, ecofriendly and economic carboxy-terminated plant fibers (PFs) were used as adsorbents for the effective in-syringe solid phase extraction (IS-SPE) of fluoroquinolone (FQ) residues from water. Based on the thermal esterification and etherification reaction of cellulose hydroxy with citric acid (CA) and sodium chloroacetate in aqueous solutions, carboxy groups grafted onto cotton, cattail, and corncob fibers were fabricated. Compared with carboxy-terminated corncob and cotton, CA-modified cattail with more carboxy groups showed excellent adsorption capacity for FQs. The modified cattail fibers were reproducible and reusable with relative standard deviations of 3.2%–4.2% within 10 cycles of adsorption-desorption. A good extraction efficiency of 71.3%–80.9% was achieved after optimizing the extraction condition. Based on carboxylated cattail, IS-SPE coupled with ultra-performance liquid chromatography with a photodiode array detector was conducted to analyze FQs in environmental water samples. High sensitivity with limit of detections of 0.08–0.25 μg/L and good accuracy with recoveries of 83.8%–111.7% were obtained. Overall, the simple and environment-friendly modified waste PFs have potential applications in the effective extraction and detection of FQs in natural waters.

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Plant fibers were functionalized by green methods.

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The bio-adsorbents were applied for the extraction of fluoroquinolones.

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The higher carboxy content in fibers improved extraction performance.

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Carboxylated cattail was efficient in the adsorption of fluoroquinolones in environmental waters.

Current Understanding of Hydrogel for Drug Release and Tissue Engineering

Due to their good absorption, satisfactory biocompatibility, and high safety, hydrogels have been widely used in the field of biomedicine, including for drug delivery and tissue regeneration. In this review, we introduce the characteristics and crosslinking methods of natural and synthetic hydrogels. Then, we highlight the design and principle of intelligent hydrogels (i.e., responsive hydrogels) used for drug release. Moreover, we introduce the application of the application of hydrogels in drug release and tissue engineering, and the limitations and research directions of hydrogel in drug release and tissue engineering are also considered. We hope that this review can provide a reference for follow-up studies in related fields.

Dihydroxybenzene isomers electrochemical sensor based on activated carbon sensitive material activated by mechanochemistry and low-dosage phosphoric acid

A dihydroxybenzene isomers electrochemical sensor based on bamboo activated carbon (MCPBAC) sensitive material activated by mechanochemistry and low-dosage phosphoric acid was fabricated in this work. The sensor, modified by MCPBAC with GCE, can significantly distinguish and sensitively measure hydroquinone (HQ) and catechol (CC). The MCPBAC exhibits a well-developed porous structure, high specific surface area, and good electrical conductivity. Using differential pulse voltammetry (DPV), wide linear ranges for both HQ and CC are 0.6-600 μM, with low detection limits (S/N = 3) for both of 0.2 μM. The dihydroxybenzene isomers electrochemical sensor has wide application prospects in the determination of trace HQ and CC in environmental water.

The Application Status of Nanoscale Cellulose-Based Hydrogels in Tissue Engineering and Regenerative Biomedicine

As a renewable, biodegradable, and non-toxic material with moderate mechanical and thermal properties, nanocellulose-based hydrogels are receiving immense consideration for various biomedical applications. With the unique properties of excellent skeletal structure (hydrophilic functional groups) and micro-nano size (small size effect), nanocellulose can maintain the three-dimensional structure of the hydrogel to a large extent, providing mechanical strength while ensuring the moisture content. Owing to its unique features, nanocellulose-based hydrogels have made excellent progress in research and development on tissue engineering, drug carriers, wound dressings, development of synthetic organs, 3D printing, and biosensing. This review provides an overview of the synthesis of different types of nanocellulose, including cellulose nanocrystals, cellulose nanofibers, and bacterial nanocellulose, and describes their unique features. It further provides an updated knowledge of the development of nanocellulose-based functional biomaterials for various biomedical applications. Finally, it discusses the future perspective of nanocellulose-based research for its advanced biomedical applications.

Pintado M, Fernandes JC, Ramos ÓL. Novel Micro- and Nanocellulose-Based Delivery Systems for Liposoluble Compounds

Poor aqueous solubility of bioactive compounds is becoming a pronounced challenge in the development of bioactive formulations. Numerous liposoluble compounds have very interesting biological activities, but their low water solubility, stability, and bioavailability restrict their applications. To overcome these limitations there is a need to use enabling delivering strategies, which often demand new carrier materials. Cellulose and its micro- and nanostructures are promising carriers with unique features. In this context, this review describes the fast-growing field of micro- and nanocellulose based delivery systems with a focus on the release of liposoluble bioactive compounds. The state of research on this field is reviewed in this article, which also covers the chemistry, preparation, properties, and applications of micro- and nanocellulose based delivery systems. Although there are promising perspectives for introducing these materials into various fields, aspects of safety and toxicity must be revealed and are discussed in this review. The impact of gastrointestinal conditions on the systems and on the bioavailability of the bioactive compounds are also addressed in this review. This article helps to unveil the whole panorama of micro- and nanocellulose as delivery systems for liposoluble compounds, showing that these represent a great promise in a wide range of applications.

Preparation of cellulose nanospheres via combining ZnCl2·3H2O pretreatment and p-toluenesulfonic hydrolysis as a two-step method

Spherical nanocelluloses, also known as cellulose nanospheres (CNS), have controllable morphology and have shown advantages as green template material, emulsion stabilizer. Herein, CNS were prepared via a new two-step method, first pretreatment of microcrystalline cellulose (MCC) using ZnCl₂·3H₂O and then acid hydrolysis of regenerated cellulose (RC) via p-toluenesulfonic acid (p-TsOH). The shape, size, crystallinity of MCC were changed, and nubbly RC with smallest size (942 nm) was obtained after 2 h pretreatment by ZnCl₂·3H₂O. CNS with high 61.3% yield were produced after acid hydrolysis (67 wt% p-TsOH) of RC at 80 °C, 6 h. The analysis of Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM) showed that CNS had an average diameter of 347 nm. CNS were present in precipitate after high-speed centrifugation, due to the high Zeta potential of -12 mV and large size. The structure of CNS was tested by Fourier Transfer Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Nuclear Magnetic Resonance (NMR), CNS had high crystallinity (cellulose II) of 61%. Thermal Gravimetric Analysis (TGA) indicated that CNS had high thermal stability (T_onset 303.3 °C, T_max 332 °C). CNS showed poor re-dispersibility in water/ethanol/THF, 1 wt% CNS could be dissolved in ZnCl₂·3H₂O. 7.37% rod-like CNC were obtained after 6 h hydrolysis. FTIR proved that p-TsOH was recovered by re-crystallization. This study provided a novel, sustainable two-step method for the preparation of spherical CNS.

Recycling Waste Cotton Cloths for the Isolation of Cellulose Nanocrystals: A Sustainable Approach

There is an interest in the sustainable utilization of waste cotton cloths because of their enormous volume of generation and high cellulose content. Waste cotton cloths generated are disposed of in a landfill, which causes environmental pollution and leads to the waste of useful resources. In the present study, cellulose nanocrystals (CNCs) were isolated from waste cotton cloths collected from a landfill. The waste cotton cloths collected from the landfill were sterilized and cleaned using supercritical CO₂ (scCO₂) technology. The cellulose was extracted from scCO₂-treated waste cotton cloths using alkaline pulping and bleaching processes. Subsequently, the CNCs were isolated using the H₂SO₄ hydrolysis of cellulose. The isolated CNCs were analyzed to determine the morphological, chemical, thermal, and physical properties with various analytical methods, including attenuated total reflection-Fourier transform-infrared spectroscopy (ATR-FTIR), field-emission scanning electron microscopy (FE-SEM), energy-filtered transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results showed that the isolated CNCs had a needle-like structure with a length and diameter of 10–30 and 2–6 nm, respectively, and an aspect ratio of 5–15, respectively. Additionally, the isolated CNCs had a high crystallinity index with a good thermal stability. The findings of the present study revealed the potential of recycling waste cotton cloths to produce a value-added product.

CytroCell: Valued Cellulose from Citrus Processing Waste

Isolating cellulose from citrus processing waste without employing chemicals has so far been an unfulfilled goal of chemical research applied to the valorization of a widely available biowaste, annually totaling >100 million tonnes. We have applied hydrodynamic cavitation using a Venturi-type reactor for the extraction of all valued bioproducts of industrial citrus processing waste in water only, directly on a semi-industrial scale. After reporting the discovery of IntegroPectin in the soluble fraction of the aqueous extract, we now report the isolation of a cellulosic material in the water-insoluble fraction of cavitated lemon and grapefruit processing waste. Named “CytroCell”, the material is cellulose of low crystallinity, high porosity, good water holding capacity and good dispersibility in water. These properties open the route to mass-scale production of a useful functional material from a cheap and abundant biowaste.

Surface-Related Kinetic Models for Anaerobic Digestion of Mi-crocrystalline Cellulose: The Role of Particle Size

In this work, for modelling the anaerobic digestion of microcrystalline cellulose, two surface-related models based on cylindrical and spherical particles were developed and compared with the first-order kinetics model. A unique dataset consisting of particles with different sizes, the same crystallinity and polymerisation degree was used to validate the models. Both newly developed models outperformed the first-order kinetics model. Analysis of the kinetic constant data revealed that particle size is a key factor determining the anaerobic digestion kinetics of crystalline cellulose. Hence, crystalline cellulose particle size should be considered in the development and optimization of lignocellulose pre-treatment methods. Further research is necessary for the assessment of impact of the crystalline cellulose particle size and surface properties on the microbial cellulose hydrolysis rate.

Valorisation of vine shoots for the development of cellulose-based biocomposite films with improved performance and bioactivity

This work reports on the valorization of Tempranillo vine shoots for the development of bio-based packaging materials. Cellulose (F3) and nanocellulose (NANO F3) were produced by the conventional method, while less purified cellulosic fractions (F2A) and nanocrystals (NANO F2A) were extracted by simplified protocols (omitting Soxhlet and alkaline treatments) to reduce production costs and environmental impact and evaluate the potential added functionalities of these less purified materials. Although most of the hemicelluloses in F2A were digested upon acid hydrolysis, a small fraction remained in NANO F2A. On the other hand, the presence of a minor xylan fraction in F3 limited the access of sulphuric acid towards the cellulose microfibrils, hindering hydrolysis and producing heterogeneous fibrillar structures in NANO F3. The obtained materials were used to produce cellulosic films, as well as blends with agar, and their performance properties were evaluated. Overall, NANO F2A films showed the best compromise between performance and sustainability and presented additional antioxidant capacity. The properties of the films could be adjusted by the incorporation of agar, improving their ductility and water permeability.

Eco-friendly nanocellulose and its biomedical applications: current status and future prospect

Cellulose is the earth's leading natural polymer. It is known for its properties like biocompatibility, high mechanical strength, cost-effectiveness and lightweight. Nanocellulose displays better properties as compared to the native cellulose fibre. The nanocellulose is very remunerative in the arenas of routine application especially in health care, food industry, sanitary products and many more. In the biomedical area, cellulose-based products are utilized in applications like wound healing, dental applications, drug delivery, antimicrobial material, etc. Nanocellulose biomaterials have been commercialised, representing the material of new generation. With the objective to comprehend the contribution of nanocellulose in the current status and future development in biomedical utilisations, the review is focused on cellulose, nanocellulose, types and sources of nanocellulose, its preparation, characteristics, constraints related to its composites through the analysis of certain scientific reports.

Nanocellulose Production: Exploring the Enzymatic Route and Residues of Pulp and Paper Industry

Increasing environmental and sustainability concerns, caused by current population growth, has promoted a raising utilization of renewable bio-resources for the production of materials and energy. Recently, nanocellulose (NC) has been receiving great attention due to its many attractive features such as non-toxic nature, biocompatibility, and biodegradability, associated with its mechanical properties and those related to its nanoscale, emerging as a promising material in many sectors, namely packaging, regenerative medicine, and electronics, among others. Nanofibers and nanocrystals, derived from cellulose sources, have been mainly produced by mechanical and chemical treatments; however, the use of cellulases to obtain NC attracted much attention due to their environmentally friendly character. This review presents an overview of general concepts in NC production. Especial emphasis is given to enzymatic hydrolysis processes using cellulases and the utilization of pulp and paper industry residues. Integrated process for the production of NC and other high-value products through enzymatic hydrolysis is also approached. Major challenges found in this context are discussed along with its properties, potential application, and future perspectives of the use of enzymatic hydrolysis as a pretreatment in the scale-up of NC production.

Acid-free preparation and characterization of kelp (Laminaria japonica) nanocelluloses and their application in Pickering emulsions

Cellulose nanofibers (CNFs) from kelp were prepared by cellulase treatment with lengths greater than 3 μm. CNFs were further oxidized by TEMPO-oxidized system, and the lengths of the oxidized CNFs (TEMPO-CNFs) were 0.6-1 μm. AFM and TEM images showed that intertwined CNFs fibers were divided into individual nanofibrils. The crystallinity of TEMPO-CNFs increased to 66.5 %. TGA analysis indicated that TEMPO-CNFs were more sensitive to temperature than cellulose and CNFs. FT-IR spectra revealed no changes in the basic cellulose structures of CNFs and TEMPO-CNFs. In the sunflower oil/water (20/80, v/v) model emulsions, the oil droplet sizes were less than 20 μm in CNFs emulsions, which became smaller in TEMPO-CNFs emulsions. Delamination was found in CNFs emulsions after three days of storage. Addition of NaCl increased the volumes of TEMPO-CNFs emulsions but enlarged the oil droplets sizes. TEMPO-CNFs emulsions had the largest volume with smallest and most homogeneous oil droplets at pH 3. TEMPO-CNFs emulsions showed good stability after storage for 30 days. Further, TEMPO-CNFs could also emulsify 50 % (v/v) of sunflower oil. All these results indicated that TEMPO-CNFs can be used in preparing Pickering emulsions.

Synthesis and conservation of cellulose nanocrystals

This work deals with the preparation of cellulose nanocrystals (CNC) from microcrystalline cellulose by acid hydrolysis, discusses how their characteristics varied according to the drying technique used for their conservation and analyzes their re-dispersion in water. A stable water dispersion of "rod" or "needle" type CNC (≈5 nm of diameter, 276 nm of length and 41 mV of Z potencial) was initially prepared and then dried by lyophilization and spray. Thus powders with similar cristalinity but different morphology were obtained, while CNC seemed to aggregate in such an extent that hindered their re-dispersion in water. Only lyophilized CNC could be re-dispersed in water and maintained stable in dispersion for at least 24 h, when working with concentrations of CNC higher than a certain minimum value (3 %) and after submitting them to intense ultrasound treatments. The tested time achieved should be enough to allow their subsequent use in several applications.

Synthesis, 99mTc-radiolabeling, and biodistribution of new cellulose nanocrystals from Dorema kopetdaghens

Cellulose nanocrystals (CNCs) are known as nano-biomaterials that can be achieved from the different sources. The designated CNCs have been successfully fabricated from the roots of Dorema kopetdaghens (Dk) plant by sulphuric acid hydrolysis method. Structural analysis has been carried out by the means of XRD, FTIR, and TGA/DTG procedures. The XRD results have indicated that the crystalline structure of CNCs had been cellulose I with the crystallinity index of 83.20% and size of 4.95 nm. The FTIR spectra have shown that the resulting samples have been related to the cellulose species. The thermal properties of CNCs have exhibited a lower thermal stability in comparison to the untreated roots. It has been indicated by the morphological analyses of FESEM, TEM, and AFM that the nanoparticles had contained a spherical shape. Also, the cytotoxicity of CNCs against A549 cell line has not exhibited any cytotoxic effects. The analysis of labeling efficiency in regards to ^99mTc-CNCs has been observed to be above 98%, while the biodistribution of radioactivity has displayed a high uptake by the kidneys and blood circulation. Therefore, it is possible to transform the low-cost by-product into a beneficial substance such as CNCs that can be utilized in bioimaging applications.

Preparation and characterization of spherical cellulose nanocrystals with high purity by the composite enzymolysis of pulp fibers

The spherical cellulose nanocrystals (CNCs) with high purity were prepared, the processes included composite enzymolysis of pulp fibers and the purification of product. The impurities in the crude product CNCs were analyzed with FTIR, coomassie brilliant blue-G250 and ionic chromatography. The pure CNCs were characterized with SEM, XRD, DLS and TGA. The results indicated that the crude CNCs was flocculated and washed twice with a dilute acid solution (pH = 2) to get pure spherical CNCs, the purity was approximate 99.99%. The obtained pure spherical CNCs had a narrow particle size distribution with diameter 15-40 nm. FTIR and XRD analyses proved that the crystal phase of the spherical CNCs did not change, but the crystallinity decreased slightly compared with pulp fibers. The thermal degradation showed that the spherical CNCs had better thermal stability than one from other methods, and the temperature of maximum weight loss rate (T_max) was 329.2 °C.

Preparation of Nanocellulose Aerogel from the Poplar (Populus tomentosa) Catkin Fiber

: The effects of chemical pretreatment on the purification of poplar (Populus tomentosa) catkin fiber and the effect of ultrasonic time for the microfibrillarization of poplar catkin fiber (PCF) were studied. The nanocellulose aerogels were prepared by freeze drying the cellulose solutions. The density, porosity, micro morphology, thermal stability and mechanical properties of the aerogels were analyzed. It was found that the dewaxing time of PCF is shorter than that of unsonicated nanocellulose. After the treatment of 0.5 wt% sodium chlorite for 2 h, the lignin of PCF was removed. After the chemical purification, the PCF was treated with 2 and 5 wt% NaOH solution and ultrasonicated for 5 and 10 min, respectively. When the ultrasonic time was 10 min, the diameter of the nanocellulose was 20-25 nm. When the ultrasonic time was 5 min, the aerogels with porous honeycomb structure can be prepared by using the nanocellulose sol of PCF as raw material. The density of the aerogels was only 0.3-0.4 mg/cm3 and the porosities of the aerogels were all larger than 99%. The difference between the pyrolysis temperature of aerogels was small, the elastic modulus of aerogels was 30–52 kPa, and the compressive strength was 22–27 kPa. With the increase of the concentration of NaOH solution (5 wt%) and ultrasonic time (10 min), the elastic modulus of aerogels increased gradually and reached the maximum value of 52 kPa, while the compressive strength reached the maximum value of 27 kPa when the PCF being treated in 5 wt% NaOH solution and was ultrasonicated for 5 min.

Microbial Beta Glucosidase Enzymes: Recent Advances in Biomass Conversation for Biofuels Application

The biomass to biofuels production process is green, sustainable, and an advanced technique to resolve the current environmental issues generated from fossil fuels. The production of biofuels from biomass is an enzyme mediated process, wherein β-glucosidase (BGL) enzymes play a key role in biomass hydrolysis by producing monomeric sugars from cellulose-based oligosaccharides. However, the production and availability of these enzymes realize their major role to increase the overall production cost of biomass to biofuels production technology. Therefore, the present review is focused on evaluating the production and efficiency of β-glucosidase enzymes in the bioconversion of cellulosic biomass for biofuel production at an industrial scale, providing its mechanism and classification. The application of BGL enzymes in the biomass conversion process has been discussed along with the recent developments and existing issues. Moreover, the production and development of microbial BGL enzymes have been explained in detail, along with the recent advancements made in the field. Finally, current hurdles and future suggestions have been provided for the future developments. This review is likely to set a benchmark in the area of cost effective BGL enzyme production, specifically in the biorefinery area.