Non-cytotoxic, highly functionalized cellulose nanocrystals with high crystallinity and thermal stability derived from a novel agromass of Elettaria cardamomum, using a soft and benign mild oxalic acid hydrolysis.

Non-cytotoxic, highly crystalline, and functionalized, thermally stable cellulose nanocrystals are extracted from the stems of Elettaria cardamom, a novel underutilised agromass, by employing a neat green, mild oxalic acid hydrolysis. The protocol involves a chemo-mechanical strategy of coupling hydrolysis with steam explosion and homogenization. The obtained CNC showed a crystallinity index of 81.51 %, an aspect ratio of 17.80 ± 1.03 and a high degradation temperature of about 339.07 °C. The extraction procedure imparted a high negative surface functionalization with a zeta potential value of -34.244 ± 0.496 mV and a polydispersity of 16.5 %. The CNC had no antibacterial activity, according to non-cytotoxic experiments conducted on four bacterial strains. This supports the notion of "One Health" in the context of AMR by demonstrating the safety of antibiotic resistance due to consistent exposure upon environmental disposal. The as-extracted nanocellulose crystals can be a potential candidate for commercial application in wide and diversified disciplines like food packaging, anti-infective surfaces for medical devices, biosensors, bioelectronics etc.

Isolation and characterization of nanocellulose from selected hardwoods, viz., Eucalyptus tereticornis Sm. and Casuarina equisetifolia L., by steam explosion method.

Extraction of nanocellulose is challenging, especially from hardwoods due to its complex chemical structure as well as structural hierarchy. In this study, nanocellulose was isolated from wood pulp of two hardwood species, namely Eucalyptus tereticornis Sm. and Casuarina equisetifolia L. by steam explosion process. Pure cellulose wood pulp was obtained through Kraft pulping process followed by alkaline and bleaching pre-treatments. Isolated nanocellulose was characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), Fourier Transformed Infrared (FTIR) Spectra, Thermogravimetric Analysis (TGA), and X-ray diffraction (XRD) studies. Nanocellulose obtained from both species showed non-significant difference with average diameter of 27.801 nm for eucalyptus and 28.690 nm for casuarina, which was confirmed from TEM and AFM images. FTIR spectra of nanocellulose showed prominent peaks corresponding to cellulose and absence of peaks corresponding to lignin. The elemental purity of nanocellulose was confirmed with EDAX detector. XRD analysis showed the enrichment of crystalline cellulose in nanocellulose, and also confirmed the significant conversion of cellulose I to cellulose II. During TG analysis the untreated fibres started to degrade earlier than the nanocellulose which indicated the higher thermal stability of nanocellulose. Highly entangled network like structure along with high aspect ratio make the nanofibres a versatile material for reinforcing the composites. This successful method can be replicated for industrial level production of cellulose nanofibres.

A review on the emerging applications of nano-cellulose as advanced coatings.

The unparalleled dependency on petroleum based sources urged the research community to focus on developing renewable products, among which nanocellulose based commodities stands at the zenith due to its abundance, biodegradability and biocompatibility. Nanocellulose in form of coatings, aerogels, hydrogels, films and membranes have its own space in the research platform. The different coating technologies like spray, bar, roller, dip and foam coating are currently employed for the fabrication. The profound surface hydroxyl groups on the cellulose helps to incorporate desired properties like antimicrobial or antioxidant activities, barrier properties, superhydrophobicity or superhydrophilicity as per the applications ranging from biomedical to material engineering. Yet, the chemistry of these coatings have to be precisely tuned for its commercialization since many factors play challenging roles while the fabrication process like adhesion, brittleness and barrier properties. The manuscript discusses these aspects of the nanocellulose based coatings along with its challenges and future perspectives.

Anticoagulant Activity of Cellulose Nanocrystals from Isora Plant Fibers Assembled on Cellulose and SiO2 Substrates via a Layer-by-Layer Approach.

In this study, we report the isolation of cellulose nanocrystals (CNCs) from Isora plant fibers by sulfuric acid hydrolysis and their assembly on hydrophilic cellulose and silicon-di-oxide (SiO2) surfaces via a layer-by-layer (LBL) deposition method. The isolated CNCs were monodispersed and exhibited a length of 200-300 nm and a diameter of 10-20 nm, a negative zetapotential (-34-39 mV) over a wide pH range, and high stability in water at various concentrations. The multi-layered structure, adsorbed mass, conformational changes, and anticoagulant activity of sequentially deposited anionic (sulfated) CNCs and cationic polyethyleneimine (PEI) on the surfaces of cellulose and SiO2 by LBL deposition were investigated using a quartz crystal microbalance technique. The organization and surface features (i.e., morphology, thickness, wettability) of CNCs adsorbed on the surfaces of PEI deposited at different ionic strengths (50-300 mM) of sodium chloride were analysed in detail by profilometry layer-thickness, atomic force microscopy and contact angle measurements. Compared to cellulose (control sample), the total coagulation time and plasma deposition were increased and decreased, respectively, for multilayers of PEI/CNCs. This study should provide new possibilities to fabricate and tailor the physicochemical properties of multilayer films from polysaccharide-based nanocrystals for various biomedical applications.

A short review on nanotechnology interventions against COVID-19.

The COVID-19 has affected all major aspects of the society in a global perspective. The role of nanotechnology is much sought after in fighting this pandemic. Advanced materials based on nanotechnology are the basis of several technologies starting from masks and personal protection equipment to specific diagnostic tools that could diminish the impact of COVID-19. Development of nanotechnology-based products is therefore an absolute necessity for fight against COVID-19. We examine the fundamental concepts related to virology, histopathologic findings and how nanotechnology can help in fighting the disease. In this review we discuss the state of the art and ongoing nanotechnology-based strategies like antiviral coatings, 3D printing and therapeutics to fight against this deadly disease. The importance of using nanoparticles in point of care tests and biosensors is also highlighted.

Rheological behaviour of nanocellulose reinforced unsaturated polyester nanocomposites.

Nanocellulose (NC) reinforced unsaturated polyester (UPR) composites were prepared by mechanical mixing process. Effect of isora nanocellulose on the properties of polyester composites has been studied in detail. Rheological properties of unsaturated polyester resin suspensions containing various amounts (0.5, 1 and 3wt%) of nanocellulose were investigated by oscillatory rheometer with parallel plate geometry. Analysis of curing revealed that the time required for gelation in NC filled UPR is lower than neat resin, which describe the catalytic action of NC on cure reaction. NC reinforced polyester suspensions showed shear thinning behaviour initially and at higher shear rates they showed Newtonian behaviour. Tensile and impact properties showed superior behaviour revealing improved interfacial bonding between nanofiller and the polymer matrix. With respect to the neat polyester the percentage increase in tensile strength of 0.5wt% NC reinforced composite is 57%. Optical and atomic force microscopic studies confirmed that the dispersion state of NC within the polyester matrix was adequate. Maximum glass transition temperature is obtained for 0.5wt% NC reinforced composite, which showed an increase of 10°C than neat resin.