Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions

Abstract

Novel cellulose-chitosan nanocomposite particles with spherical shape were successfully prepared via mixing of aqueous biopolymer solutions in three different ways. Macroparticles with diameters in the millimeter range were produced by dripping cellulose dissolved in cold LiOH/urea into acidic chitosan solutions, inducing instant co-regeneration of the biopolymers. Two types of microspheres, chemically crosslinked and non-crosslinked, were prepared by first mixing cellulose and chitosan solutions obtained from freeze thawing in LiOH/KOH/urea. Thereafter epichlorohydrin was applied as crosslinking agent for one of the samples, followed by water-inoil (W/O) emulsification, heat induced sol-gel transition, solvent exchange, washing and freeze-drying. Characterization by X-ray photoelectron spectroscopy, total elemental analysis, and Fourier transform infrared spectroscopy confirmed the prepared particles as being true cellulose-chitosan nanocomposites with different distribution of chitosan from the surface to the core of the particles depending on the preparation method. Field emission scanning electron microscopy and laser diffraction was performed to study the morphology and size distribution of the prepared particles. The morphology was found to vary due to different preparation routes, revealing a core shell structure for macroparticles prepared by dripping, and homogenous nanoporous structure for the microspheres. The non-crosslinked microparticles exhibited a somewhat denser structure than the crosslinked ones, which indicated that crosslinking restricts packing of the chains before and under regeneration. From the obtained volume-weighted size distributions it was found that the crosslinked microspheres had the highest median diameter. The results demonstrate that not only the mixing ratio and distribution of the two biopolymers, but also the morphology and nanocomposite particle diameters are tunable by choosing between the different routes of preparation.

Chitosan-cellulose particles as delivery vehicles for limonene fragrance

“…Furthermore, the shell material must have no reactivity with the core material, present low viscosity at high concentration, protect the active ingredient against external factors, and ensure good emulsion-stabilization properties (Zhu et al, 2012). Over the years, different studies have been carried out using chitosan, cellulose, including cellulose derivatives, as composite materials (Table 1) (Yang et al, 2016).…”

“…Cellulose, isolated from plant tissues for the first time in 1838 by the French chemist Payen (Olivera et al, 2016), is a linear homopolymer composed of D-anhydroglucopyranose units, which are connected by β(1-4)-glycosidic bonds (Alves, 2015). Cellulose is the most abundant polymer in the world comprising unique properties such as the strong mechanical strength, biocompatibility and thermal stability (Duarte, 2014;Yang et al, 2016). Furthermore, it is natural, renewable, environmentally benign, cost-efficient and non-toxic (Olivera et al, 2016).…”

Cellulose‐Based Fully Green Triboelectric Nanogenerators with Output Power Density of 300 W m−2

“…The cellulose was dissolved according to the reported method. [ 36,37 ] R‐cellulose films were prepared by casting the solution onto glass plates (with a thickness corresponding to the desired thickness in the dry state) and immersed into an ethanol regeneration bath for 2 h. The films were placed in a Milli‐Q water bath to wash away the LiOH and urea, and the water was changed daily until pH 7 was reached. The films were dried at room temperature for ≈8 h; to avoid shrinkage, each film was placed on a plastic plate, and all film edges were taped.…”

“…The R‐cellulose was produced in our laboratory using an environmentally friendly method. [ 36–38 ] A 20 µm thick flexible and transparent film ( Figure a) with a density of 1.4 g cm −3 was made from dissolved cellulose. The surface of the film was characterized by scanning electron microscopy (SEM) in secondary electron (SE) mode (Figure 1a).…”

Pineapple peel carboxymethyl cellulose/polyvinyl alcohol/mesoporous silica SBA-15 hydrogel composites for papain immobilization

“…Until now, hydrogels based on natural or synthetic polymers, such as cellulose (Wu et al, 2014), chitosan (Yang et al, 2016), alginate (Mohammed et al, 2015), gelatin (Chen et al, 2014), carrageenan (Evingür & Pekcan, 2013;Long et al, 2015) and polyvinyl alcohol (PVA) (Moreno-Cortez et al, 2015;Song et al, 2016) have aroused considerable interest as unique support materials for enzyme immobilization.…”