Natural cellulose, a sustainable bioresource, is highly abundant in nature. Cellulosic materials, particularly those that explore and employ such materials for industrial use, have recently attracted significant global attention in the field of material science because of the unique properties of cellulose. The hydroxyl groups enable the formation of intra- and inter-molecular hydrogen bonding and the arrangement of cellulose chains in a highly ordered crystalline zone, with the remaining disordered structure referred to as an amorphous region. The crystalline areas of cellulose are well-known as cellulose nanocrystals (CNCs). In the present study, we extracted CNCs from pure cellulose isolated from waste jute fibers by sulfuric acid hydrolysis, followed by characterization. Pure cellulose was isolated from jute fibers by treating with sodium hydroxide (20% w/w) and anthraquinone (0.5%) solution at 170 °C for 2 h, followed by bleaching with chlorine dioxide and hydrogen peroxide solution. CNCs were isolated from pure cellulose by treating with different concentrations (58% to 62%) of sulfuric acid at different time intervals (20 min to 45 min). The FTIR study of the CNCs reveals no peak at 1738 cm⁻¹, which confirms the absence of hemicellulose in the samples. The CNCs obtained after 45 min of acid hydrolysis are rod-shaped, having an average length of 800 ± 100 nm and width of 55 ± 10 nm, with a high crystallinity index (90%). Zeta potential significantly increased due to the attachment of SO₄²⁻ ions on the surface of CNC from −1.0 mV to about −30 mV, with the increment of the reaction time from 20 min to 45 min, which proved the higher stability of CNC suspension. Crystallinity increased from 80% to 90% when the reaction time was increased from 20 to 45 min, respectively, while a crystallite size from 2.705 to 4.56 nm was obtained with an increment of the acid concentration. Acid hydrolysis enhanced crystallinity but attenuated the temperature corresponding to major decomposition (Tmax) at 260 °C and the beginning of degradation (Ti) at 200 °C due to the attachment of SO₄²⁻ ions on the surface, which decreased the thermal stability of CNC. The second degradation at 360 °C indicated the stable crystal structure of CNC. The endothermic peak at 255 °C in the DTA study provided evidence of sulfated nanocrystal decomposition and the recrystallization of cellulose I to cellulose II, the most stable structure among the other four celluloses. The proposed easy-to-reproduce method can successfully and efficiently produce CNCs from waste jute fibers in a straightforward way.

The most affordable type of tablet is the immediately compressible tablet, which uses microcrystalline cellulose (MCC), a popular pharmaceutical excipient, as a filler or binder. To make it compatible with different active drugs and excipients, we tried to change some physical properties of the MCC. In the current study, we used a chelating agent to pretreat the waste cotton before pulping, bleaching, and finally, hydrochloric acid degradation with a concentration of 2N at 100 °C temperature for 20 min to prepare MCC. The prepared MCC was treated with different concentrations of sodium hydroxide at room temperature or at −20 °C followed by precipitation with hydrochloric acid or ethanol with complete washing with distilled water till neutralization. Evaluation of the degree of polymerization (DP) and FT-IR spectrum confirm the identity of the microcrystalline cellulose. The DP was found to be 216. The bulk density of the unmodified MCC was 0.21 while that of modified MCC varied from 0.253 to 0.594. The modified MCC powder showed good flow properties compared to the unmodified MCC as evaluated by the Hausner index, Carr’s index and the angle of repose. The scanning electron microscopy (SEM) of the MCC revealed that the rod shape has been changed to an oval shape due to treatment with sodium hydroxide at −20 °C. The X-ray crystallographic (XRD) analysis indicated that the unmodified MCC and standard MCC showed the crystallinity index (CrI) value of 86.82% and 87.63%, respectively, while the value ranges from 80.18% to 60.7% among the modified MCC powder. The differences in properties of the MCC might be due to the variation of rearrangement of the cellulose chain among the MCC particles due to treatment with different concentrations of a base at different temperatures and precipitation environments. This has enabled us to prepare MCC with different properties which might be compatible with different drugs.

Microcrystalline cellulose (MCC) is a popular pharmaceutical excipient, used as a filler or binder in directly compressible tablets, and is the most economical form of all available tablets. In the present research work, we pretreated waste paper with a chelating agent followed by pulping, bleaching, and subsequent hydrothermal degradation with hydrochloric acid at a concentration of 0.5 mol/l and at a 150°C temperature for 120 minutes to produce MCC. The derived MCC was dried at 60°C for 3 hours, ground, and graded into two types based on the particle size. Grade 1 had a particle size of ≤75 microns, while grade 2 had a particle size of 75–125 microns. The derived MCC was chemically identified by an iodinated ZnCl2 solution. Evaluation of the degree of polymerization (DP) and Fourier transforminfrared spectroscopy spectrum further confirmed the identity of the MCC. From the value of intrinsic viscosity of the MCC in cuene, the DP was found to be 126 and 191 for Avicel PH101 and the derived MCC, respectively. The morphological study of derived MCC types by the scanning electron microscopy method suggested that their shapes were very similar to that of Avicel PH101, while the size of MCC grade 1 was very similar to the marketed Avicel PH101. Moreover, the derived MCC types were comparable to the commercial Avicel PH101 based on different physicochemical parameters associated with flow property such as bulk density, tapped density, Hausner’s ratio, Carr’s index, angle of repose, and ash value. The applicability of the derived MCC as a directly compressible excipient was further investigated through the formulation of an uncoated aceclofenac immediate-release tablet. The various tablet parameters like hardness, friability, disintegration, and dissolution time all complied with standard specifications.

The pandemic, well-known as COVID-19, has been caused by the coronavirus SARS-CoV-2 and it has distinct characteristics from other coronavirus-related epidemics. This pandemic has been ravaging the whole world for more than a year now, and no drugs or vaccines have been found to eliminate this virus from the infected people effectively; only physical measures like social distancing, hand washing and face-mask wearing have been taken to reduce its spread and very recently Veklury (remdesivir) has been permitted by the USFDA to manage the critical patients. This disease can be asymptomatic, but when it is symptomatic, it presents with respiratory problems and cold- or flu-like symptoms, which can be diagnosed with a chest CT and confirmed with RT-PCR tests. In this review, the taxonomy and structure of SARS-CoV-2 and history, transmission, epidemiology, pathology, clinical features and impacts of the COVID-19 have been discussed. A summary of possible drug targets, attempted physical and chemical measures, as well as vaccine candidates, has also been provided. How this coronavirus is different from other coronaviruses, the obstacles in managing this disease and the possibility of a second wave have also been reviewed. This review represents a wide range of information regarding COVID-19 and intends to be used as a comprehensive overview in this regard.