Cellulose nanocrystals extracted from rice husk using the formic/peroxyformic acid process: isolation and structural characterization

Cellulose derived from biomass is a renewable resource with numerous applications. Using formic/peroxyformic acid at atmospheric pressure, cellulose nanocrystals (CNC) were isolated from rice husk (RH) in this study. This method was an excellent way to get rid of lignin and hemicelluloses from RH. The cellulose was subsequently acid hydrolyzed by H2SO4 (64%) for 30 minutes at 45 °C. The chemical and microstructure analysis showed that the lignin and hemicellulose contents of raw RH had been eliminated, and the crystallinity content of CNC was 67.16%. According to transmission electron microscopy (TEM) morphological analysis, CNC measured 19 ± 3.3 nm in diameter, 195 ± 24 nm in length, and 10.2 ± 6.8 in aspect ratio. The thermal stability of RH and CNC was also investigated using thermogravimetric analysis (TGA). These encouraging findings demonstrated the potential for reusing RH agricultural waste to create CNC and include nanocomposites as a reinforcing material.

Epidermis of Cereus hildmannianus as a biomimetic scaffold for tissue engineering

A thin plastic-like film separated from the epidermis of Cereus hildmannianus has excellent tensile strength, resistance to water and high antimicrobial activity and supports the growth of mouse fibroblast cells. Cactuses are one of the most under explored plant species with high potential for food, materials, pharmaceutical and other applications. Although studies have shown the ability of cactuses to be used for food, as a source for fibers, as reinforcement for composites and other applications, the role of individual layers and their properties has been studied to a limited extent. In this paper, a thin translucent layer was separated from the epidermis of C. hildmannianus and studied for its composition, structure and properties. The layer is composed of about 73% cellulose and 2% lignin and morphologically, shows surface with uneven and serrated edges. Films with length of up to 36 cm, strength of 6.8 MPa and elongation of 2.5% could be peeled from the cactus suggesting their suitability for food packaging and other applications. X-ray diffraction patterns and FTIR spectrums indicated that the films are similar to that of cellulose and major thermal degradation occurred above 280°C. Compared to standards, the cactus films showed about 41% and 44% inhibition against gram positive and gram negative bacteria and 67% inhibition of the common fungal strain (A. niger). Films showed high stability in water and to common chemicals. When used as substrates for mouse fibroblast cell growth, no cytotoxicity was observed and the cactus peel supported the attachment and proliferation of cells demonstrating potential to be used as a biomaterial for tissue engineering applications.

Current trends in cacti drying processes and their effects on cellulose and mucilage from two Colombian cactus species

The effect of temperature and drying technologies on mucilage and cellulose (obtained by the microwave-assisted extraction technique, MAE) from Opuntia ficus-indica (OFI) and Austrocylindropuntia cylindrica (CC) was determined using a conventional oven (CO) and Refractive Window (RW). Mathematical modeling was performed from drying kinetics data using the Lewis, Henderson-Pabis, Page, and Logarithmic models. Activation Energy (Ea) and Diffusivity (D) were also determined. The model with the best fit was the logarithmic one, with a correlation coefficient (R²) greater than 0.99. The obtained activation energies were 22.81 kJ mol^-1 for Refractance window (RW) and 31.44 kJ mol^-1 using conventional hot air drying (CO) while a diffusivity of 2.9 ∗10^-8 m² s^-1 for RW and 1.3∗10^-8 m² s^-1 for CO were found as well. According to our results, a greater drying efficiency and a less chemical deterioration of the plant sample are obtained by drying with Refractance window.

Depolymerization of lignin by extracellular activity of Pycnoporus cinnabarinus, to obtain cellulose

Cellulose can be used to produce biofuels and many other products like pharmaceutical goods, food supplements, cosmetics, bio-plastics, etc. Lignocellulosic materials, like O. ficus indica residuals, are a heterogeneous biopolymer formed mainly by lignin, hemicellulose and cellulose. Lignin provides protection to the plants against chemical and microbial degradation, but it can be degraded by white rot fungi species, like Pycnoporus cinnabarinus. Since cellulose molecules are arranged in regular bundles enveloped by hemicellulose and lignin molecules, it is necessary to brake lignin and hemicellulose molecules to recover cellulose for its use in bioprocess. In this work, a biotechnological process for cellulose recovery from cactus waste through depolymerization of lignin by P. cinnabarinus, is presented. The delignification is carried out by aerobic culture in batch stirred bioreactors, with a liquid culture medium enriched with nutrients and minerals with O. ficus indica residuals as the unique carbon source, during eight-day span under continuous feeding of oxygen. A factorial design of experiments (DOE) for eight sets of factor values was selected for this study. The factors were: particle size, pH level, and process temperature. For each experiment, biomass, total reducing carbohydrates (TRC) and dissolved oxygen (DO) concentrations were measured every 24 h. At the end of each experiment, the percentage of delignification, and cellulose recovery was measured by Infrared (IR) spectroscopy. Up to 67% of delignification and 22% of cellulose recovery were obtained by the process. These results were analyzed by a factorial DOE in order to maximize each response individually and to optimize both responses together. The delignification of Opuntia ficus indica thorns has not been previously reported to our knowledge.

Valorization of Pineapple Residues from the Colombian Agroindustry to Produce Cellulose Nanofibers

Cellulose nanofiber is the world’s most advanced biomass material. Most importantly, it is biodegradable. In this work, nanofibers were obtained from pineapple leaves, a large solid waste in Colombia, using a combined extraction method (chemical procedures and ultrasound). The native fibers were bleached, hydrolyzed, treated with ultrasound, and characterized by scanning electron microscopy (SEM), infrared analysis (FTIR), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). As a comparison, a commercial microcrystalline cellulose sample was analyzed, which demonstrated the efficiency of cellulose extraction. The nanofibers had a diameter and a length of 18 nm and 237 nm, respectively, with a maximum degradation temperature of 306 °C. The analysis showed the efficiency of acid treatment combined with ultrasound to obtain nanofibers and confirmed that pineapple residues can be valorized by this method. These results indicate that lignocellulosic matrices from pineapple leaves have potential application for obtaining polymeric-type composite materials. Due to their morphology and characteristic physical properties, the cellulose nanofibers obtained in this work could be a promising material for use in a wealth of fields and applications such as filter material, high gas barrier packaging material, electronic devices, foods, medicine, construction, cosmetics, pharmacy, and health care, among others.

Composite of polylactic acid and microcellulose from kombucha membranes

Polylactic acid (PLA) is one of the main components of biodegradable and biocompatible composites. Bacterial cellulose from kombucha membranes is an excellent candidate to be used as a natural filler of eco-composites because it is renewable, has low cost, low density, and acceptable specific strength properties, and is biodegradable. The study aimed to prepare composites of PLA and bacterial cellulose to produce a biodegradable and compostable material. The bacterial microcellulose was obtained from kombucha membranes and blended with PLA by extrusion. The composites contained a PLA with 1%, 3%, and 5% of cellulose. We characterized the PLA, bacterial microcellulose, and composites to ascertain their size and aspect, degree of crystallinity, distribution of the cellulose into PLA, and their mechanical properties. We observed an increase in crystallinity proportional to the cellulose content for the blends and found that the 3% cellulose blend withstands the stress of up to 40 MPa and temperatures up to 120°C before distortion.

A Review on Opuntia Species and its Chemistry, Pharmacognosy, Pharmacology and Bioapplications

Background:

Opuntia species, locally known as prickly pear was used for various purposes as food, medicine, beverage, source of dye and animal food. Many studies have revealed its pharmacology activity from time to time. This review is a collection of chemistry, pharmacognosy, pharmacology and bioapplications of the cactus family.

Methods:

Many sources were used to collect information about Opuntia species such as Pub med, Google scholar, Agris, science direct, Embase, Merk index, Wiley online library, books and other reliable sources. This review contains studies from 1812 to 2019.

Results:

The plants from the cactus family offer various pharmacological active compounds including phenolic compounds, carotenoids, betalains, vitamins, steroids, sugar, amino acids, minerals and fibers. These bioactive compounds serve various pharmacological activities such as anticancer, antiviral, anti-diabetic, Neuroprotective, anti-inflammatory, antioxidant, Hepatoprotective, antibacterial, antiulcer and alcohol hangover. According to various studies, Opuntia species offer many bioapplications such as fodder for animal, soil erosion, prevention, human consumption and waste water decontamination. Finally, different parts of plants are used in various formulations that offer many biotechnology applications.

Conclusion:

Different parts of Opuntia plant (fruits, seeds, flowers and cladodes) are used in various health problems which include wound healing, anti-inflammatory and urinary tract infection from ancient times. Nowadays, researches have extended several pharmacological and therapeutic uses of Opuntia species as discussed in this review. Many in-vitro and in-vivo models are also discussed in this review as the proofs of research findings. Various research gaps have been observed in current studies that require attention in the future.

Valorization of Colombian fique (Furcraea bedinghausii) for production of cellulose nanofibers and its application in hydrogels

Cellulose nanofibers were obtained from the Colombian fique (Furcraea bedinghausii) and Acrylic hydrogels (H) and reinforced acrylic hydrogels with fique nanofibres (HRFN) were synthesized, using the solution polymerization method. The extraction was carried out using a combined extraction method (chemical procedures and ultrasound radiation). The raw material (NAT-F), bleached fibers (B-F), hydrolyzed fibers and fibers treated with ultrasound (US-F) were characterized by infrared spectroscopy (FTIR) and thermal stability analysis; also, in order to have a comparison criterion, a commercial microcrystalline cellulose sample (CC) was analyzed, which demonstrated the extraction of fique cellulose. The surface morphology of the NAT-F and the B-F was determined by scanning electron microscopy and the average particle size of the nanofibers was made through transmission electron microscopy. In H y HRFN the strain percent and compression resistance (Rc) were measured. The fique nanofibers showed diameter and length averages of 25.2 ± 6.2 nm and 483.8 ± 283.2 nm respectively. Maximum degradation temperature was 317 °C. HRFN presented higher compression resistance (16.39 ± 4.30 kPa) and this resistance was 2.5 greater than the resistance of H (6.49 ± 2.48 kPa). The results indicate that fique lignocellulosic matrix has potential application for obtaining polymeric type composite materials.

Isolation and characterization of cellulose nanocrystals from Cucumis sativus peels

Cucumber (Cucumis sativus) peels waste being a potential cellulosic sources, were used for extracting cellulose nanocrystals (CNCs), and characterized in the present study. Firstly, the cucumber peels were purified chemically through acid, alkali, and bleaching treatments for cellulose isolation. Later obtained cellulose was acid (60 wt% H₂SO₄) hydrolyzed at 45 ℃ for 45 min to obtain CNC45 suspension, and again 10 min sonicated for CNC45-S10 suspension. The effect of sonication on the particle size of CNC45, and CNC45-S10 were investigated with Dynamic light Scattering and Atomic force microscopy. The microstructural changes, thermal, and crystalline properties of resulting fibers and CNC45 were analysed after each treatments through scanning electron microscopy, thermo-gravimetric analyser, and X-ray diffraction respectively. The acid-hydrolysed CNC45 from cucumber peels showed rod-like shape with high crystallinity (74.1 %), excellent thermal stability (>200 °C), and negative zeta potential values (<-30 mV), and CNC45 can be used as potential nanofillers.