Carboxylated Cellulose Nanocrystals Developed by Cu-Assisted H₂O₂ Oxidation as Green Nanocarriers for Efficient Lysozyme Immobilization

Abstract

Cellulose nanocrystals (CNCs), having a high specific surface area and versatile surface chemistry, provide considerable potential to interact by various mechanisms with enzymes for nano-immobilization purposes. However, engineering chemically safe CNCs, suitable for edible administrations, presents a significant challenge. A reliable carboxylate form of H-CNCs was formed using H 2 O 2 oxidation of softwood pulp under mild thermal conditions. Negatively charged carboxyl groups (∼0.9 mmol g −1 ) played a key role in lysozyme immobilization via electrostatic interactions and covalent linkages, as evidenced by Fourier transform infrared and 13 C cross-polarization magic angle spinning nuclear magnetic resonance spectroscopies. Adsorption isotherms showed a high loading capacity of H-CNCs (∼240 mg g −1 ), and fitting the data to the Langmuir model confirmed monolayer coverage of lysozyme on their surface. Using a non-toxic coupling agent, 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride, lysozyme-conjugated H-CNCs were developed with an immobilization yield of ∼65% and relative catalytic activity of ∼60%, similar to lysozyme adsorption on H-CNCs. These H-CNC−lysozyme nanohybrids, rationally processed via safe and green strategies, are specifically exploitable as catalytically active emulsifiers in food and pharmaceutical sectors.

Preparation and Surface Functionalization of Carboxylated Cellulose Nanocrystals

“…Koshani and van den Ven also developed a nanocarrier system using cCNCs for the immobilization of lysozymes [ 66 ]. cCNCs were targeted as a potential nanocarrier for enzymes due to their non-toxicity, ease of fabrication and modification, biodegradability, and biocompatibility.…”

Natural Emulgel from Dialdehyde Cellulose for Lipophilic Drug Delivery

“…22 To easily track the carbon changes in the original cellulose pulp and DAC, Figure S6 is also provided and interpreted according to our previous papers. 22,27 The broadness and overlapping of the carbon peaks in DAC are another proof of the self-associating behavior of DAC macromolecules.…”

“…The absence of carbonyl signals demonstrates that the aldehyde groups of DAC macromolecules have formed hemiacetal linkages in the interaction with primary hydroxyl groups on DAC chains . To easily track the carbon changes in the original cellulose pulp and DAC, Figure S6 is also provided and interpreted according to our previous papers. , The broadness and overlapping of the carbon peaks in DAC are another proof of the self-associating behavior of DAC macromolecules.…”

Recent Progress in Production Methods for Cellulose Nanocrystals: Leading to More Sustainable Processes

“…The yield of the CNCs was 52.01%, significantly higher than the yield of 27.61% obtained by hydrolysis with 64% sulfuric acid in the same study. Other oxidants including sodium metaperiodate, [ 115 ] Fe 2+ /H 2 O 2 [ 116 ] and Cu‐assisted H 2 O 2 oxidation [ 117 ] have also been reported.…”