Synthesis and application of photo-active carboxymethyl cellulose derivatives

Biosafety consideration of nanocellulose in biomedical applications: A review

Nanocellulose-based biomaterials have gained significant attention in various fields, especially in medical and pharmaceutical areas, due to their unique properties, including non-toxicity, high specific surface area, biodegradability, biocompatibility, and abundant feasible and sophisticated strategies for functional modification. The biosafety of nanocellulose itself is a prerequisite to ensure the safe and effective application of biomaterials as they interact with living cells, tissues, and organs at the nanoscale. Potential residual endogenous impurities and exogenous contaminants could lead to the failure of the intended functionalities or even serious health complications if they are not adequately removed and assessed before use. This review summarizes the sources of impurities in nanocellulose that may pose potential hazards to their biosafety, including endogenous impurities that co-exist in the cellulosic raw materials themselves and exogenous contaminants caused by external exposure. Strategies to reduce or completely remove these impurities are outlined and classified as chemical, physical, biological, and combined methods. Additionally, key points that require careful consideration in the interpretation of the biosafety evaluation outcomes were discussed to ensure the safety and effectiveness of the nanocellulose-based biomaterials in medical applications.

Preparation and characterization of photosensitive methacrylate-grafted sodium carboxymethyl cellulose as an injectable material to fabricate hydrogels for biomedical applications

Injectable materials have attracted great attention in the manufacture of in situ forming hydrogels for biomedical applications. In this study, a facile method to prepare methacrylic anhydride (MA)-modified sodium carboxymethyl cellulose (CMC) as an injectable material for the fabrication of hydrogels with controllable properties is reported. The chemical structure of the series of MA-grafted CMC (CMCMAs) with different MA contents was confirmed by Fourier transform infrared and nuclear magnetic resonance spectroscopy, and the properties of CMCMAs were characterized. Then, the CMCMAs gel (CMCMAs-G) was fabricated by crosslinking of MA under blue light irradiation. The gelation performances, swelling behaviors, transmittance, surface porous structures and mechanical properties of CMCMAs-G can be controlled by varying the content of MA grafted on the CMC. The compressive strength of CMCMAs-G was measured by mechanical compressibility tests and up to 180 kPa. Furthermore, the in vitro cytocompatibility evaluation results suggest that the obtained CMCMAs-G exhibit good compatibility for cell proliferation. Hence, our strategy provides a facile approach for the preparation of light-sensitive and an injectable CMC-derived polymer to fabricate hydrogels for biomedical applications.

Novel cellulose derivative containing aminophenylacetic acid as sustainable adsorbent for removal of cationic and anionic dyes

The synthesis and characterization of a novel cellulose derivative as a potential sustainable adsorbent for cationic and anionic dyes are described through processing in ionic liquids. Cellulose was solubilized in ionic liquid with tosyl chloride to form tosyl cellulose which reacted with 4-aminophenylacetic acid through nucleophilic substitution mechanism. The new cellulose derivative was characterized and explored as an effective adsorbent for methylene blue (MB) and methyl orange (MO) removal, and the adsorption behaviors were investigated with various models. The adsorption behavior of the cellulose derivative followed Langmuir and pseudo-second-order models, and the maximum adsorption efficiency recorded 135 and 106 mg/g for MB and MO, respectively. There is possibility that the enhanced adsorption capacity of the cellulose derivative is due to the carboxylic and amino functional groups that provide sufficient active sites to enhance dye molecule affinity. The adsorption results demonstrate that the cellulose derivative containing aminophenylacetic acid was efficient adsorbent for removals of MB and MO.

Synthesis and characterization of photo-crosslinkable cinnamate-functionalized pectin

The polysaccharide pectin (PC) was functionalized with the photo-responsive cinnamic acid hydrazide (CN) to produce the photo-crosslinkable PC-CN hydrogel material that was then evaluated as a carrier for encapsulation of the drug model aspirin. Cinnamic acid hydrazide was first prepared and then incorporated with the abundant -COOCH₃ groups on the pectin chain via hydrazide linkage. The obtained polymeric derivatives have been characterized by means of instrumental techniques including FTIR and NMR. The obtained PC-CN hydrogels with different cinnamic functionality were also freeze-dried and examined by SEM, which indicated more coherent hydrogel texture by increasing the cinnamic functionalization. The effect of the photo-curing time, as well as the functionalization degree, on the swelling and gelation of the obtained hydrogel was also studied to evaluate the potential of the developed material in drug delivery systems using aspirin as a common and available drug model. The developed PC-CN hydrogel materials exhibited high potential as a drug carrier that enables the control of the drug release via optimizing both the degree of cinnamic functionality and the photo-curing time.

Recent Advances of Stimuli-Responsive Polysaccharide Hydrogels in Delivery Systems: A Review

Hydrogels obtained from natural polymers have received widespread attention for their excellent biocompatible property, nontoxicity, easy gelation, and functionalization. Polysaccharides can regulate the gut microbiota and improve the intestinal microenvironment, thus exerting the healthy effect of intestinal immunity. In an active substance delivery system, the extent and speed of the substance reaching its target are highly dependent on the carrier. Thus, the smart active substance delivery systems are gradually increasing. The smart polysaccharide-hydrogels possess the ability in response to external stimuli through changing their volume phase and structure, which are applied in various fields. Natural polysaccharide-based hydrogels possess excellent characteristics of environmental friendliness, good biocompatibility, and abundant sources. According to the response type, natural polysaccharide-based hydrogels are usually divided into stimulus-responsive hydrogels, including internal response (pH, temperature, enzyme, redox) and external response (light, electricity, magnetism) hydrogels. The delivery system based on polysaccharides can exert their effects in the gastrointestinal tract. At the same time, polysaccharides may also take part in regulating the brain signals through the microbiota-gut-brain axis. Therefore, natural polysaccharide-hydrogels are considered as promising biomaterials, which can be designed as delivery systems for regulating the gut-brain axis. This article reviews the research advance of stimulus-responsive hydrogels, which focus on the types, response characteristics, and applications for polysaccharide-based smart hydrogels as delivery systems.

Natural Polymer-based Stimuli-responsive Hydrogels

The abilities of intelligent polymer hydrogels to change their structure and volume phase in response to external stimuli have provided new possibilities for various advanced technologies and great research and application potentials in the medical field. The natural polymer-based hydrogels have the advantages of environment-friendliness, rich sources and good biocompatibility. Based on their responsiveness to external stimuli, the natural polymer-based hydrogels can be classified into the temperature-responsive hydrogel, pH-responsive hydrogel, light-responsive hydrogel, electricresponsive hydrogel, redox-responsive hydrogel, enzyme-responsive hydrogel, magnetic-responsive hydrogel, multi-responsive hydrogel, etc. In this review, we have compiled some recent studies on natural polymer-based stimuli-responsive hydrogels, especially the hydrogels prepared from polysaccharides. The preparation methods, properties and applications of these hydrogels in the medical field are highlighted.

Ionic liquids-modified cellulose coated magnetic nanoparticles for enzyme immobilization: Improvement of catalytic performance

In this work, ionic liquids-modified magnetic carboxymethyl cellulose nanoparticles (IL-MCMC) were prepared and used as supports for enzyme immobilization. The specific activity of immobilized lipase PPL-IL-MCMC was 1.43 and 2.81 folds higher than that of free PPL and PPL-MCMC, respectively. Water contact angle analysis indicated that the introduction of ionic liquids increased the hydrophobicity of supports, which in tune induced the lid-opening of lipase, allowing its active sites to become more accessible. In addition, the affinity between lipase and substrate immobilized on the prepared supports was enhanced. The same method was also applied to analyze immobilize penicillin G acylase (PGA) to further investigate the general applicability of the method. The results showed that the immobilized PGA exhibited higher stability than many other reported PGAs. The developed composites may be utilized as excellent supports for enzyme immobilization in industrial application.

Comparison between gelatin/carboxymethyl cellulose and gelatin/carboxymethyl nanocellulose in tramadol drug loaded capsule

The comparison between Tramadol drug loaded microspheres prepared from gelatin/sodium carboxymethyl cellulose (NaCMC) and those prepared from gelatin/sodium carboxymethyl nanocellulose (NaCMNC) in presence of glutaraldehyde (GA) as cross linker was carried out. Cellulose isolated from rice straw was hydrolyzed using 65% H₂SO₄ to prepare nanoparticles with average particle size ranging from 44 to 66 nm. Various formulations of gelatin/NaCMC and gelatin/NACMNC were prepared with different ratios of amounts of gelatin, NaCMC/NaCMNC, and GA. Microspheres were characterized by fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy. The FTIR spectroscopy results confirmed the structure of microsphere and the absence of chemical interactions among Tramadol drug, polymer, and crosslinking agent. The ultraviolet spectroscopy showed 68% efficiency of the drug encapsulation using cellulose, while 55% for nanocellulose. The equilibrium water uptake decreased from 646 to 329% for cellulose microspheres, when the amount of GA increased from 5 to 10 mL. In contrast, the equilibrium water uptake decreased significantly from 501 to 33.7% for nanocellulose microspheres. The yield percentage enhanced from 54.67 to 80% for nanocellulose microspheres. The in vitro release rate was also calculated. The percent cumulative release of drug was significantly increased at the first 2 h and then a slow increase was further noticed. In general, the nanocellulose microsphere showed lower release rates than cellulose. None of the prepared microsphere presented 100% drug release until 12 h.

Peroxide-periodate co-modification of carboxymethylcellulose to prepare polysaccharide-based tanning agent with high solid content

Dialdehyde carboxymethylcellulose (DCMC) solution generally has quite low solid content, which inevitably limits its industrial application. In this work, carboxymethylcellulose sodium (Na-CMC) was pre-degraded using H₂O₂ followed by periodate oxidation for preparing DCMC with high solid content as practical tanning agent. Pre-degradation conditions optimization showed that H₂O₂ dosage most impacted the tanning effect of DCMC, and the M_w and viscosity of Na-CMC underwent remarkable reduction. FT-IR and ¹H NMR illustrated that aldehyde group was successfully introduced into DCMC after periodate oxidation. Under the optimized conditions, the solid content of DCMC could be improved to around 30%. This DCMC could endow tanned leather with high shrinkage temperature and satisfactory fiber dispersion. Besides, DCMC tanned leather had comparable physical and organoleptic properties to those of leathers tanned by chrome tanning agent and commercial polyaldehyde tanning agent TWT. This suggests the prospect of DCMC with high solid content as useful tanning agent.

Carbohydrate-based nanomaterials for biomedical applications

Carbohydrates are abundant biomolecules, with a strong tendency to form supramolecular networks. A host of carbohydrate-based nanomaterials have been exploited for biomedical applications. These structures are based on simple mono- or disaccharides, as well as on complex, polymeric systems. Chemical modifications serve to tune the shapes and properties of these materials. In particular, carbohydrate-based nanoparticles and nanogels were used for drug delivery, imaging, and tissue engineering applications. Due to the reversible nature of the assembly, often based on a combination of hydrogen bonding and hydrophobic interactions, carbohydrate-based materials are valuable substrates for the creations of responsive systems. Herein, we review the current research on carbohydrate-based nanomaterials, with a particular focus on carbohydrate assembly. We will discuss how these systems are formed and how their properties are tuned. Particular emphasis will be placed on the use of carbohydrates for biomedical applications. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Carboxymethyl cellulose thiol-imprinted polymers: Synthesis, characterization and selective Hg(II) adsorption

Sulfur containing ion imprinted polymers (S-IIPs) were applied for the uptake of Hg(II) from aqueous solution. Cysteamine which was used as the ligand for Hg(II) complexation, was grafted along the epichlorohydrin crosslinked carboxylated carboxymethyl cellulose polymer chain through an amide reaction. The adsorption ability of S-IIPs towards Hg(II) was investigated by kinetic and isotherm models, which, corresponding, showed that the adsorption process followed a pseudo-second-order, fitted well with the Langmuir isotherm with a maximum adsorption capacity of 80 mg/g. Moreover, thermodynamic studies indicated an endothermic and spontaneous reaction with the tendency of an enhanced randomness at the surface of the S-IIPs with temperature increases. S-IIPs indicated a high degree of selectivity towards Hg(II) in the presence of Cu²⁺, Zn²⁺, Co²⁺, Pb²⁺ and Cd²⁺. Furthermore, the efficiency of S-IIPs was also evaluated against real samples showing 86.78%, 91.88%, and 99.10% recovery for Hg(II) wastewater, ground water and tap water, respectively. In this study, the adsorbent was successfully regenerated for five cycles, which allows for their reuse without significant loss of initial adsorption capability.

A New Way to Produce Cellobiose Carbonates Using Green Chemistry

The preparation of cellulose derivatives using green (i.e., environmentally friendly) reagents would improve sustainability and reduce concerns arising from the use of non-green reagents. The objective of this work was to prepare cellobiose carbonate using a green reagent, dimethyl carbonate. The carbonation reaction was carried out in the presence of ethanolic potassium hydroxide solution and dimethyl carbonate for 6 h at a range of temperatures (25-70 °C). A cellobiose derivative was successfully prepared with a recovered yield of more than 70 % and characterized by FTIR and NMR spectroscopy techniques. The presence of a grafted disaccharide with a degree of substitution higher than 2 was determined by (13) C NMR analysis. The spectra of the prepared cellobiose carbonate exhibited peaks that were associated with cellulose molecules (C1 -C6 ) and corresponded to carbonate functions at around 159.4 ppm.