Investigating effects of high cellulase concentration on the enzymatic hydrolysis of the sisal cellulosic pulp

Cellulose Acetate Microparticles Synthesized from Agave sisalana Perrine for Controlled Release of Simvastatin

Simvastatin (SIM) is widely prescribed to treat hyperlipidemia, despite its limitations, such as a short half-life and low oral bioavailability. To overcome these drawbacks, the development of a controlled-release formulation is desirable. This study aims to develop a microparticulate system based on cellulose acetate (ACT) obtained from Agave sisalana Perrine to promote a controlled SIM release. SIM-loaded microparticles (SMP) were prepared using the solvent emulsification-evaporation method. Several parameters were evaluated, including particle size, surface charge, morphology, encapsulation efficiency, thermochemical characteristics, crystallinity, and in vitro release profile. ACT exhibited favorable flow properties after acetylation, with a degree of substitution values superior to 2.5, as confirmed by both the chemical route and H-NMR, indicating the formation of cellulose triacetate. The obtained SMP were spherical with an average size ranging from 1842 to 1857 nm, a zeta potential of -4.45 mV, and a high SIM incorporation efficiency (98%). Thermal and XRD analyses revealed that SIM was homogeneously dispersed into the polymeric matrix in its amorphous state. In vitro studies using dialysis bags revealed that the controlled SIM release from microparticles was higher under simulated intestinal conditions and followed the Higuchi kinetic model. Our results suggest that ACT-based microparticles are a promising system for SIM delivery, which can improve its bioavailability, and result in better patient compliance.

Reversible immobilization of cellulase on gelatin for efficient insoluble cellulose hydrolysis

Immobilized enzymes are one of the most common tools used in enzyme engineering, as they can substantially reduce the cost of enzyme isolation and use. However, efficient catalysis of solid substrates using immobilized enzymes is challenging, hydrolysis of insoluble cellulose by immobilized cellulases is a typical example of this problem. In this study, inspired by bees and honeycombs, we prepared gelatin-modified cellulase (BEE) and gelatin hydrogels (HONEYCOMB) to achieve reversible recycling versus release of cellulase through temperature-responsive changes in the triple-stranded helix-like interactions between BEE and HONEYCOMB. At elevated temperatures, BEE was released from HONEYCOMB and participated in hydrolytic saccharification. After 24 h, the glucose yields of both the free enzyme and BEE reached the same level. When the temperature was decreased, BEE recombined with HONEYCOMB to facilitate the effective separation and recycling of BEE from the system. The enzymatic system retained >70 % activity after four reuse cycles. In addition, this system showed good biocompatibility and environmental safety. This method increases the mass transfer capacity and enables easy recovery of immobilized cellulase, thereby serving as a valuable strategy for the immobilization of other enzymes.

Cellulose nanocrystals: Pretreatments, preparation strategies, and surface functionalization

Cellulose nanocrystals (CNCs) have attracted great interest from researchers from academic and industrial areas because of their interesting structural features and unique physicochemical properties, such as magnificent mechanical strength, high surface area, and many hydroxyl groups for chemical modification, low density, and biodegradability. CNCs are an outstanding contender for applications in assorted fields comprehensive of, e.g., biomedical, electronic gadgets, water purifications, nanocomposites, membranes. Additionally, a persistent progression is going on in the extraction and surface modification of cellulose nanocrystals to fulfill the expanding need of producers to fabricate cellulose nanocrystals-based materials. In this review, the foundation of nanocellulose that emerged from lignocellulosic biomass and recent development in extraction/preparation of cellulose nanocrystals and different types of cellulose nanocrystal surface modification techniques are summed up. The different sorts of cellulose modification reactions that have been discussed are acetylation, oxidations, esterifications, etherifications, ion-pair formation, hydrogen bonding, silanization, nucleophilic substitution reactions, and so forth. The mechanisms of surface functionalization reactions are also introduced and considered concerning the impact on the reactions. Moreover, the primary association of cellulose and different forms of nanocellulose has likewise been examined for beginners in this field.