Although pulping processes from wood are well-cemented technology, the emergence of bio-based nanotechnology, as well as the increase in concern about the environmental impact that these processes can have, calls for a reevaluation of the impacts that the traditional pulping methods have on the surfaces of the fibers and how variances will then affect the generation and properties of the nanocellulose materials, that will then impact the different applications that can be derived from them. Since literature tends to focus on one method and then characterize it, the aim of this review is to discuss the properties that have been reported of different fibers and nanofibers depending on the wood source, the chemical pulping method selected (kraft or sulfite methods), and the bleaching or lack of it and then compare the effects that these can have in properties such as crystallinity, chemical composition, surface charge, and functional groups present on the surface.
Exploiting cellulose nanocrystals’ high aspect
ratio and
tailorable surface for immunological biosensors has been hindered
by the relatively limited research on using commonly available sulfated
cellulose nanocrystals (CNCs) for antibody immobilization and by the
low hydrolytic stability of dried assemblies produced from sulfated
CNCs. Herein, we report a reaction scheme that enables both hydrolytic
stability and antibody immobilization through 3-aminopropyl-triethoxysilane
and glutaric anhydride chemistry. Immobilization was demonstrated
using three model antibodies used in the detection of the cancer biomarkers:
alpha-fetoprotein, prostate-specific antigen, and carcinoembryonic
antigen. Thermogravimetric analysis coupled with Fourier-transform
infrared spectroscopy provided evidence of CNC modification. Quartz
crystal microbalance with dissipation monitoring was used to monitor
binding during each step of the immobilization scheme as well as binding
of the corresponding antigens. The general reaction scheme was tested
using both aqueous CNC dispersions and CNC films. Film modification
is slightly simpler as it avoids centrifugation and washing steps.
However, modifying the dispersed CNCs provides access to their entire
surface area and results in a greater capacity for antigen binding.
With increasing global water temperatures and nutrient runoff in recent decades, the blooming season of algae lasts longer, resulting in toxin concentrations that exceed safe limits for human consumption and for recreational use. From the different toxins, microcystin-LR has been reported as the main cyanotoxin related to liver cancer, and consequently its abundance in water is constantly monitored. In this work, we report a methodology for decorating cellulose nanofibrils with β-cyclodextrin or with poly(β-cyclodextrin) which were tested for the recovery of microcystin from synthetic water. The adsorption was followed by Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), allowing for real-time monitoring of the adsorption behavior. A maximum recovery of 196 mg/g was obtained with the modified by cyclodextrin. Characterization of the modified substrate was confirmed with Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric Analysis (TGA), and Atomic Force Microscopy (AFM).
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