Cellulose Nanocrystals Content Research Articles

Thermal Characterizations of HPMC/PVA Impregnated with CNC Electrospun Nanofibers

Interest in the nanotechnology invention has been increased among the researcher and industries which lead to many investigations and studies to develop a product with better performance. In this research, hydroxypropyl methylcellulose (HPMC) and poly (vinyl) alcohol (PVA) nanofiber with the ratio 1:1 and the concentration of 5 wt% and 7 wt%, respectively, were successfully fabricated by using electrospinning technique. The HPMC/ PVA was then blended with the different concentration of cellulose nanocrystal (CNC) at 2 wt%, 4 wt%, 6 wt% and 8 wt%. The SEM results of HPMC/PVA/CNC nanofibers shown random orientation fibers with average diameters of 62.28 nm - 252.80 nm. The TGA results showed three major weight loss that prove the decomposotion of HPMC/PVA/CNC was occured with three maximum temperature peaks around 69 °C, 290 °C and 392 °C. As for DSC, the peak intensity of the Tg in the electrospun nanofiber are decreasing as the concentration of CNCs increased might be due to the interfering of the CNC with the crystallization of the polymer causing mobility of the amorphous regions to be higher. Therefore, the study on the thermal properties of HPMC/PVA incorporated with CNCs nanofibers could be a reference for various potential applications.

Effect of Different Concentration of Cellulose Nanocrystals Comprising Hydroxyethyl Cellulose / Poly(Vinyl Alcohol) as a Bone Tissue Engineering Scaffold

In this study, biodegradable scaffolds based on hydroxyethyl cellulose (HEC) (5 wt%) and poly (vinyl alcohol) (PVA) (15 wt%) with different percentages of celullose nanocrystal (CNC) (1 and 7 wt%) were fabricated by lyophilization method to get highly porous scaffolds. These scaffolds were made water insoluble by cross-linking via heat treatment. The morphology and thermal properties of HEC/PVA/CNCs scaffolds were characterized by using Scanning Electron Microscope (SEM) and Thermogravimetric Analysis (TGA). The morphological study showed that both prepared scaffold have highly porous structures with good pore interconnected structure. It was observed that thermal properties of scaffolds increased significantly as the concentration of CNCs increased. Cytotoxicity studies on scaffolds were carried out by utilizing human fetal osteoblast (hFOB) cells using DAPI nuclear stain and then confirmed using SEM. hFOB cells were able to attach and spread on all scaffolds. Incorporated CNCs as reinforcing nanofiller on scaffolds promising a superior functionality in bone tissue engineering.

The role of CNC surface modification on the structural, thermal and electrical properties of poly(vinylidene fluoride) nanocomposites

This work shows the effect of cellulose nanocrystal surface charge on the morphology, structure, thermal and dielectric properties of poly(vinylidene fluoride) nanocomposites. CNCs extracted through sulfuric acid hydrolysis were modified using sodium hydroxide and cationization treatments to yield CNCs with zeta-potential values of − 26.1 ± 3.7 and − 4.4 ± 0.3 mV in comparison with the original highly-negative − 45.2 ± 1.1 mV. Nanocomposites where then obtained through doctor-blade casting followed by room temperature drying. CNC incorporation allows obtaining PVDF with 100% of γ-phase. An increase of the real dielectric constant e′, dielectric loss tan δ and AC conductivity was observed by increasing CNC content. More importantly, these values are further boosted upon CNC surface-modification, suggesting the pivotal role of the CNC–PVDF interface. We conclude that the sulfate half-ester removal increase the amount of exposed –OH groups with increase the amount of accumulated charges at the PVDF–CNC interfaces. The effect of cellulose nanocrystal (CNC) surface charge on the morphology, structure, thermal and dielectric properties of poly(vinylidene fluoride) (PVDF) nanocomposites is here shown. By removing the sulfate half-ester it is possible to increase the amount of exposed –OH groups, enhancing the accumulated charges at the PVDF–CNC interfaces and improving the electric performance.

Plant nanocellulose and its composite hydrogel membranes-based polyvinyl alcohol/hyaluronic acid for biomedical applications: Extraction, characterization, and in vitro bioevaluation

Needle-like cellulose nanocrystals (CNCs) were prepared from useless rice straw, which posed problems of environmental pollution in Egypt during its disposal in the burning process. Cellulose was obtained using an alkaline treatment, followed by a bleaching process and acid hydrolysis producing a high yield of CNCs ~12 ± 3 (%, w/w). Resultant CNCs were instrumentally characterized by FTIR, XRD, transmission electron microscopy (TEM), Brunauer–Emmett–Teller, and particle potential analyses; moreover, antimicrobial activity, hemolysis, and cytotoxicity were bioassessed. XRD exhibited an elevated crystallinity index of approximately 98%, and thermal decomposition of thermogravimetric analysis thermograph ranged from ~245 to 480°C. The TEM investigation showed that the nonaggregated needle-like nanocrystals diameter ranged from ~20 to 60 nm. Interestingly, CNCs at high concentrations (1,000 μg/ml) did not affect the viability of HFB-4 and WI38 human normal cell lines. Polyvinyl alcohol (PVA)/hyaluronic acid (HA) hydrogel membranes were reinforced with various concentrations of CNCs [0.25, 0.5, and 1.0% (w/v)] and prepared by the solution-casting method using citric acid as a crosslinker. The results revealed that using CNCs as nanofillers up to 0.5% enhanced dramatically the mechanical properties of membranes and exhibited good swelling capacity, biocompatibility, and antimicrobial activity, compared to hydrogel free CNCs. Therefore, the PVA/HA/CNCs membranes might have great potential in wound dressing application and it can be regarded as suitable to be developed into targeted nanocarriers or nanofillers for biomedical applications.

Synergistic improvement for mechanical, thermal and optical properties of PVA-co-PE nanofiber/epoxy composites with cellulose nanocrystals

The rapid development of optoelectronic devices puts forward higher requirements for flexible transparent films with good mechanical and thermal properties. To further improve the mechanical, thermal and optical properties of the PVA-co-PE nanofiber reinforced epoxy composite film, cellulose nanocrystals (CNCs) was selected as modifier to enhance the interfacial adhesion between the reinforced nanofibers and matrix. Benefiting from excellent hydrophily, high strength, transparency and ultra-low thermal expansion coefficient (CTE) of CNCs, dramatic improvements in tensile strength, transparency and thermal stability of CNCs/PVA-co-PE/epoxy composites were observed over pure PVA-co-PE nanofiber/epoxy film. Typically, when the CNCs concentration was 3%, the transparency of CNCs/PVA-co-PE/epoxy film increased from 83.4% to 90.4%, the tensile strength increased from 11.4 MPa to 16.4 MPa, the CTE dropped from 33 to 10 ppm/K. Furthermore, as the reinforcement for matrix and the carrier for functional materials, the CNCs/PVA-co-PE nanofiber membrane was used to prepare the patterned photochromic and thermochromic films encapsulated with epoxy, indicating the potential application of CNCs/PVA-co-PE/epoxy composites in the light emitting devices.

Mechanical Properties and Cytotoxicity of Differently Structured Nanocellulose-hydroxyapatite Based Composites for Bone Regeneration Application.

The nanocomposites were prepared by synthesizing (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibrils (TCNFs) or cellulose nanocrystals (CNCs) with hydroxyapatite (HA) in varying composition ratios in situ. These nanocomposites were first obtained from eggshell-derived calcium and phosphate of ammonium dihydrogen orthophosphate as precursors at a stoichiometric Ca/P ratio of 1.67 with ultrasonication and compressed further by a uniaxial high-pressure technique. Different spectroscopic, microscopic, and thermogravimetric analyses were used to evaluate their structural, crystalline, and morphological properties, while their mechanical properties were assessed by an indentation method. The contents of TCNF and CNC were shown to render the formation of the HA crystallites and thus influenced strongly on the composite nanostructure and further on the mechanical properties. In this sense, the TCNF-based composites with relatively higher contents (30 and 40 wt %) of semicrystalline and flexible TCNFs resulted in smoother and more uniformly distributed HA particles with good interconnectivity, a hardness range of 550–640 MPa, a compression strength range of 110–180 MPa, an elastic modulus of ~5 GPa, and a fracture toughness value of ~6 MPa1/2 in the range of that of cortical bone. Furthermore, all the composites did not induce cytotoxicity to human bone-derived osteoblast cells but rather improved their viability, making them promising for bone tissue regeneration in load-bearing applications.

Crystallization kinetics and morphology of small concentrations of cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) melt-compounded into poly(lactic acid) (PLA) with plasticizer

In the present study, very small concentrations of CNCs and CNFs were melt-compounded into PLA using a solvent-free process where poly(ethylene glycol) (PEG) was used to disperse the nanoparticles in PLA. As a comparison, the commercial nucleant, talc, was processed similarly into PLA. CNC and CNF were shown to be efficient nucleants for PLA, similar to talc, and conventional Avrami and Lauritzen-Hoffman analysis of the crystallization behavior was performed for isothermal temperatures from 90 °C to 130 °C across all compositions. From the Avrami analysis, the crystallization rate, half-time, and Avrami exponent were calculated and suggested a synergistic effect of nanocellulose and PEG, even at very small concentrations. The crystallization half-time was lower than talc at higher temperatures indicating faster crystallization for samples containing nanocellulose under certain conditions. Analysis of secondary nucleation revealed a decrease in the surface energy for CNC containing samples, further suggesting that, given the enhanced mobility of plasticized PLA, very small concentrations of CNC are effective nucleation agents. Lastly, scanning electron microscopy was used to correlate the crystal morphology of chemically etched samples with the thermal analysis. Coarsening of the microstructure was observed initially with the addition of PEG, and further coarsening was observed upon the addition of nanocellulose.

Heat-induced whey protein isolate gels improved by cellulose nanocrystals: Gelling properties and microstructure

Cellulose nanocrystals (CNC) were successfully prepared from wheat bran, and their effects on the gelling properties and microstructure of heat-induced whey protein isolate (WPI) gels were investigated. The results showed that the water holding capacity, gel strength, viscoelasticity, and thermal stability of the composite gels were improved by increasing the CNC concentration from 0 to 1.0 % (w/v). The incorporation of CNC restricted water mobility and facilitated conformation conversion of the secondary structure from α-helix to β-sheet. CNC has good compatibility with the protein matrixes at relatively low concentrations. At higher CNC concentrations, the agglomerated CNC can serve as an active dehydrating agent to absorb moisture in the protein matrixes, which promotes unfolding and cross-linking of the protein molecules. Moreover, the active filling effects of CNC contributed to the formation of a compact and homogeneous gel structure. Therefore, naturally sourced CNC is suggested as a potential gel modifier in food industry.

Polymer-Induced Modification of Cellulose Nanocrystal Assemblies in Aqueous Suspensions

The effect of adsorbing, nonionic polymers on the phase behavior of cellulose nanocrystals (CNCs) is of interest for design and preparation of functional hybrids. CNC assembly into a chiral nematic phase (N*) was investigated in the presence of highly hydrated poly(vinyl alcohol) (HPVA), low hydrated PVA (LPVA), and poly(vinylpyrrolidone) (PVP). Mapping of the nano-to-micro structure via small-angle X-ray scattering (SAXS), cryogenic transmission electron microscopy (cryo-TEM), and polarized light microscopy (POM) reveals the presence of nematic islands already at very low CNC concentrations. While the polymer-decorated CNCs preserve the structure of the native N* phase, solvated PVA at concentrations above the semidilute regime disrupt the CNCs’ self-organization into the liquid-crystalline phase, whereas PVP does not. It is suggested that the specific structure of the polymers rather than their physical properties or depletion interactions dominates the nanostructure and phase behavior of the polymer–CN...

Effect of Ionic Surfactants on the Viscoelastic Properties of Chiral Nematic Cellulose Nanocrystal Suspensions.

The gelation of cellulose nanocrystal (CNC) suspensions is explored in the presence of two ionic surfactants, namely, sodium dodecyl sulfate (SDS) with a negatively charged head and cetyltrimethylammonium bromide (CTAB) with a positively charged head. The viscosity profile of pure CNC suspensions indicated that at concentrations greater than 5 wt %, they exhibit gel-like behavior, where the viscosity shows a single shear-thinning profile. However, at concentrations lower than 1 wt %, the suspension shows isotropic behavior and experiences a transition to chiral nematic biphasic domains at increasing CNC concentration. In addition, the effect of CTAB, SDS, and NaCl on the surface charge of CNCs is analyzed and coupled with rheological measurements in order to study the relative importance of surfactants and ionic strength on the viscoelastic properties of the CNC suspensions. The mechanism of CNC/surfactants and CNC/CNC interactions leading to the gelation of CNC suspensions is also investigated. It was found that the addition of both ionic surfactants results in the gelation of biphasic chiral nematic CNC suspensions by fostering cross-linking between individual CNCs at smaller concentrations. In the case of CTAB, a gradual and ongoing increase in the viscoelastic moduli was observed with the increase of surfactant concentration, implying the induction of dominant attractive forces between CNCs by surfactant molecules. However, the presence of SDS stimulates both attractive and repulsive forces whose relative dominance controls the viscoelastic properties and gelation.

The role of cellulose nanocrystals in biocompatible starch-based clicked nanocomposite hydrogels

Starch-based nanocomposite hydrogels were successfully prepared by the Diels-Alder click cross-linking reaction between furan-functionalized starch derivative and a water-soluble tetrafunctional maleimide compound, adding cellulose nanocrystals (CNC) as nanoreinforcement. The effect of increasing the CNC content on rheological and swelling properties as well as on the morphology of the hydrogels was analyzed. Besides, in order to evaluate the applicability of the as-prepared hydrogels as delivery systems, drug release measurements and in vitro cytotoxicity assays were also performed. It was found that the prepared nanocomposite hydrogels presented higher stiffness as the CNC content increased. The incorporation of the nanocrystals modified the internal porous microstructure of the hydrogels, affecting consequently both the swelling capacity and the drug-delivery kinetics. Moreover, the prepared nanocomposite hydrogels showed non-toxic behavior, demonstrating their potential applicability in the biomedical field, especially as sustained drug delivery systems.

Poly(propylene carbonate)/poly(3‐hydroxybutyrate)‐based bionanocomposites reinforced with cellulose nanocrystal for potential application as a packaging material

Poly(propylene carbonate) (PPC) is an aliphatic polycarbonate synthesized from carbon dioxide and propylene oxide. Poly(3‐hydroxybutyrate) (PHB) is a type of thermoplastic polyester produced by biological fermentation. The blending of PHB with PPC can effectively enhance the mechanical properties and barrier properties of PPC. Bionanocomposites of PPC/PHB enhanced by cellulose nanocrystal (CNC) are prepared via a two‐step process using polyethylene glycol as a carrier. Results show that the oxygen barrier properties of the composites increased with the increase of the CNC content. When the CNC content is 1 wt%, the oxygen barrier performance increases nearly 18 times. The assumed model can predict the barrier performance of composites with the combined influence of morphology and CNC distribution. This will make PPC/PHB/CNC nanocomposites a very promising degradable material for food packaging application.

Structure and thermal stability of cellulose nanocrystal/polysulfone nanocomposites

The thermal stability of nanocomposites of cellulose nanocrystals (CNC) dispersed in polysulfone (PSf) was studied to understand the influence of heating rate and CNC concentration using thermogravimetric analysis (TGA). While heating rate was found to have a positive influence on the degradation onset temperature and the maximum degradation rate (Tmax) of these nanocomposites. The influence of CNC concentration appeared to be relatively low on these parameters. PSf/CNC nanocomposites with up to 2 wt.% CNC were found to follow first order degradation kinetics and at higher concentrations, better fit was seen with second-order degradation kinetics. The activation energy associated with nanocomposites degradation, determined using Kissinger method, revealed strong stabilizing effect of PSf matrix on CNC filler. FTIR analysis showed signature peak shifts that correlated with PSf/CNC interactions. On the other hand, the CNC filler had marginal influence on the stability of PSf matrix. Master decomposition curve (MDC) and weight-time-temperature plots were constructed from the obtained activation energies to describe the time-temperature dependence of the PSf/CNC nanocomposite pyrolysis.

Plasmonic Metamaterial Gels with Spatially Patterned Orientational Order via 3D Printing.

Optical properties can be programmed on mesoscopic scales by patterning host materials while ordering their nanoparticle inclusions. While liquid crystals are often used to define the ordering of nanoparticles dispersed within them, this approach is typically limited to liquid crystals confined in classic geometries. In this work, the orientational order that liquid crystalline colloidal hosts impose on anisotropic nanoparticle inclusions is combined with an additive manufacturing method that enables engineered, macroscopic three-dimensional (3D) patterns of co-aligned gold nanorods and cellulose nanocrystals. These gels exhibit polarization-dependent plasmonic properties that emerge from the unique interaction between the host medium’s anisotropic optical properties defined by orientationally ordered cellulose nanocrystals, from the liquid crystal’s gold nanorod inclusions, and from the complexity of spatial patterns accessed with 3D printing. The gels’ optical properties that are defined by the interplay of these effects are tuned by controlling the gels’ order, which is tuned by adjusting the gels’ cellulose nanocrystal concentrations. Lithe optical responsiveness of these composite gels to polarized radiation may enable unique technological applications like polarization-sensitive optical elements.

Morphological characteristics and thermal, rheological, and mechanical properties of cellulose nanocrystals‐containing biodegradable poly(lactic acid)/poly(ε‐caprolactone) blend composites

ABSTRACTThis work investigates the effect of cellulose nanocrystal (CN) loading on the properties of polylactide/poly(ε‐caprolactone) (PLA/PCL) (70/30) blend processed in a twin‐screw extruder as a potential material that can be utilized in various applications where biodegradation is highly desired. The morphological analysis revealed a reduction in droplet size of dispersed PCL phase upon addition of CN at low concentrations (1 and 2 wt %) with maximum reduction at 2 wt % which led to maximum improvement in mechanical properties. The reinforcing effect of CN in increasing the DMA storage modulus of the prepared systems was noticed when CN concentration was increased. Further, CN enhanced the crystallization of PCL, whereas the cold crystallization of PLA remained the same with CN addition. Both melt strength and viscosity of PLA improved with the incorporation of PCL and CN. In general, a green composite material with improved properties was successfully prepared using an environmentally friendly filler material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48665.

Manufacture of a super-stable green gel pen ink based on CNC-indigo

Gel pens are the most popular writing instruments at present with the unique rheological properties for their excellent writing performance. It’s challenging to develop a super-stable gel pen ink, which is often manufactured based on complex ink components. In this paper, a new method was innovatively proposed to prepare a gel pen ink based on cellulose nanocrystals (CNC) and indigo. The effects of CNC concentration, storage temperature, acidity, alkalinity, and electrolyte content on the stability of the new CNC gel pen ink were investigated. When CNC concentration was between 3.81% and 7.08%, indigo usage was 1.5%, surfactant OP-10 dosage was 0.05%, the prepared new CNC gel pen ink exhibited good writing performance and super-stable dispersion stability. A little amount of acid, alkali and salt content would not impact the stability of the new CNC gel pen ink, which increased the feasibility of its industrial production and long-term storage or use.

Phase separation and performance of polyethersulfone/cellulose nanocrystals membranes

We investigate the effect of cellulose nanocrystals (CNC) as a hydrophilic nanoparticle on the characteristics of polyethersulfone (PES) based membranes. The membranes are fabricated using typical nonsolvent induced phase separation (NIPS) method. We study the radius of gyration and aggregation of PES in dimethylformamide in the presence of CNC, the rheological behavior of dope dispersions, and the morphology, permeability, irreversible fouling, MWCO, ζ-potential, water contact angle and mechanical properties of final membranes. Small-angle X-ray scattering (SAXS) analysis show that high CNC and water concentrations lead a transition from mass fractal to surface fractal scattering. Addition of CNC into the PES solution induces the formation of an interconnected polymer network, yet excess CNC loading eventually results in a heterogeneous composite with diminished mechanical properties. Additionally, an increase in the viscosity and elasticity of the dope dispersions is observed in the presence of CNC, which changes the morphology of the final membranes. The CNC concentration up to 1.5 wt% increases the water permeability of membrane while retaining the same dye rejection and fouling resistance as the neat one. The enhanced performance of PES/CNC membrane is related to the rheological properties and phase separation behavior of the cast dispersion. The results of water contact angle analysis confirm the higher wettability of the CNC filled membranes. Incorporation of up the 2 wt% CNC leads to a higher strength but lower ductility in comparison to the neat PES membrane.

Production of Nylon-6/Cellulose Nanocrystal Composite Films Using Solvent Dissolution

Nylon-6 (N6) composites were incorporated with cellulose nanocrystals (CNCs) extracted from sugarcane bagasse via solvent dissolution. The effect of the CNC content was estimated at 0, 1, 3, 5 and 7 wt%. Atomic force microscopy images showed that the diameter and length of the obtained CNCs were 52.4 ± 14.8 and 400.38 ± 104.8 nm, respectively. Fourier transform infrared analysis illustrated the increasing dominant peak intensity of cellulose in the composites with a higher CNC content. X-ray diffraction and mechanical analysis determined the optimum improvement in crystallinity index and Young’s modulus in loading 1 wt% of CNCs, with values of 64.37 ± 0.12% and 675.27 MPa, respectively. The highest opacity value of the N6/CNC composites was 8.592 ± 0.062 for N6/CNC-7%. Moreover, CNCs decreased the thermal property of the N6 composites. These results suggested that CNCs have great potential to reinforce N6 polymers.

Gradient Poly(ethylene glycol) Diacrylate and Cellulose Nanocrystals Tissue Engineering Composite Scaffolds via Extrusion Bioprinting.

Bioprinting has advanced drastically in the last decade, leading to many new biomedical applications for tissue engineering and regenerative medicine. However, there are still a myriad of challenges to overcome, with vast amounts of research going into bioprinter technology, biomaterials, cell sources, vascularization, innervation, maturation, and complex 4D functionalization. Currently, stereolithographic bioprinting is the primary technique for polymer resin bioinks. However, it lacks the ability to print multiple cell types and multiple materials, control directionality of materials, and place fillers, cells, and other biological components in specific locations among the scaffolds. This study sought to create bioinks from a typical polymer resin, poly(ethylene glycol) diacrylate (PEGDA), for use in extrusion bioprinting to fabricate gradient scaffolds for complex tissue engineering applications. Bioinks were created by adding cellulose nanocrystals (CNCs) into the PEGDA resin at ratios from 95/5 to 60/40 w/w PEGDA/CNCs, in order to reach the viscosities needed for extrusion printing. The bioinks were cast, as well as printed into single-material and multiple-material (gradient) scaffolds using a CELLINK BIOX printer, and crosslinked using lithium phenyl-2,4,6-trimethylbenzoylphosphinate as the photoinitiator. Thermal and mechanical characterizations were performed on the bioinks and scaffolds using thermogravimetric analysis, rheology, and dynamic mechanical analysis. The 95/5 w/w composition lacked the required viscosity to print, while the 60/40 w/w composition displayed extreme brittleness after crosslinking, making both CNC compositions non-ideal. Therefore, only the bioink compositions of 90/10, 80/20, and 70/30 w/w were used to produce gradient scaffolds. The gradient scaffolds were printed successfully and embodied unique mechanical properties, utilizing the benefits of each composition to increase mechanical properties of the scaffold as a whole. The bioinks and gradient scaffolds successfully demonstrated tunability of their mechanical properties by varying CNC content within the bioink composition and the compositions used in the gradient scaffolds. Although stereolithographic bioprinting currently dominates the printing of PEGDA resins, extrusion bioprinting will allow for controlled directionality, cell placement, and increased complexity of materials and cell types, improving the reliability and functionality of the scaffolds for tissue engineering applications.

Injectable Biocompatible Hydrogels from Cellulose Nanocrystals for Locally Targeted Sustained Drug Release.

Injectable hydrogels from biocompatible materials are in demand for tissue engineering and drug delivery systems. Here, we produce hydrogels from mere cellulose nanocrystals (CNCs) by salt-induced charge screening. The injectability of CNC hydrogels was assessed by a combination of shear and capillary rheology, revealing that CNC hydrogels are conveyed via plug flow in capillaries allowing injection with minimal impact on mechanical properties. The potential of CNC hydrogels as drug carriers was elaborated by the in vitro release of the model protein bovine serum albumin (BSA), poorly water soluble tetracycline (TC), and readily soluble doxorubicin (DOX) into physiological saline and simulated gastric juice. For TC, a burst release was observed within 2 days, whereas BSA and DOX both showed a sustained release for 2 weeks. Only DOX was released fully from the hydrogels. The different release patterns were attributed to drug size, solubility, and specific drug-CNC interactions. The biocompatibility of CNC hydrogels and maintained bioactivity of released DOX were confirmed in a HeLa cell assay. The drug release was modulated by the incorporation of sucrose or xanthan gum in CNC hydrogels, whereas altering CNC concentration showed minor effects. The release into simulated gastric juice at pH 2 ceased for BSA due to charge inversion and electrostatic complexation, but not for smaller TC. Thus, CNC hydrogels may act as pH-responsive delivery systems that preserve drugs under gastric conditions followed by pH-triggered release in the duodenum.