Fluorescent and thermo-responsive cellulose nanocrystals (CNCs) with tuned polymer brushes were prepared via surface initiated activators generated by electron transfer for atom transfer radical polymerization.

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Lignocellulosic biomass, such as wood, grass, agricultural, and forest residues, are potential resources for the production of bioethanol. The current biochemical process of converting biomass to bioethanol typically consists of three main steps: pretreatment, enzymatic hydrolysis, and fermentation. For this process, pretreatment is probably the most crucial step since it has a large impact on the efficiency of the overall bioconversion. The aim of pretreatment is to disrupt recalcitrant structures of cellulosic biomass to make cellulose more accessible to the enzymes that convert carbohydrate polymers into fermentable sugars. This paper reviews several leading acidic, neutral, and alkaline pretreatments technologies. Different pretreatment methods, including dilute acid pretreatment (DAP), steam explosion pretreatment (SEP), organosolv, liquid hot water (LHW), ammonia fiber expansion (AFEX), soaking in aqueous ammonia (SAA), sodium hydroxide/lime pretreatments, and ozonolysis are intensively introduced and discussed. In this minireview, the key points are focused on the structural changes primarily in cellulose, hemicellulose, and lignin during the above leading pretreatment technologies.

Nanocellulose/gelatin composite cryogels with controllable porosity, reversible network structure and good biocompatibility were constructed via the chemical cross-linking of dialdehyde starch and further used as the carriers for controlled 5-fluorouracil (5-FU) release. The pore structure of the composite cryogels was successfully tuned by changing the dosages and ratios of nanofibrillated cellulose (NFC), gelatin and dialdehyde starch. Under the same density of cryogels, increasing the NFC content results in higher specific surface area and porosity. The swelling ratios first increase and then decrease with an increase in the contents of NFC and dialdehyde starch, and the swelling ratios of cryogels are relatively higher in neutral medium than those in acidic medium. The drug loading improvement is favored by increasing the NFC content and cross-linking degree. The drug-loaded cryogels show controllable and sustained release of 5-FU in vitro, which is attributed to the hydration of gelatin and reversible hydrolysis of acetal/hemiacetal. The behaviors of drug release are dependent on the structures of cryogels including the NFC/gelation ratio, density and cross-linking degree as well as the pH values. The sustained release time of the cryogel carrier is able to reach 12 h in a simulated intestinal environment.

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Novel interconnected PVA-based hydrogels with controlled porous structure prepared by freezing/thawing and porogen technique are presented in this study.

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