Grafting of oxidized carboxymethyl cellulose with hydrogen peroxide in presence of Cu(II) to chitosan and biological elucidation

Tuning a green carboxymethyl cellulose-based pre-tanning agent via peroxide oxidation for high chrome exhaustion in leather industry

The low chrome uptake by collagen in the conventional tanning process leads to the pollution of the wastewater. Due to environmental concerns, leather scientists are already searching for innovative ways to produce pre-tanning agents as a high exhaustion chrome tanning auxiliary. Herein, a novel kind of pre-tanning agent is engineered by converting carboxymethyl cellulose (CMC) to oxidized carboxymethyl cellulose (OCMC) via the hydrogen peroxide process. FT-IR and carboxyl content analysis demonstrated the increase in carboxyl content after oxidation. After that, the obtained OCMC was utilized as a pre-tanning agent, resulting in a high exhaustion of chrome (92.76 %) which is 27.76 % more than conventional chrome tanning (65 %), and the amount of chrome in wastewater reduced to 7.24 %. The hydrothermal stability of wet-blue increased by increasing the uptake of chrome (Ts = 118 °C). The obtained crust leather represented excellent mechanical properties (Tensile strength: 305.68 kg/cm2; tear strength: 50 kg/cm) and desirable organoleptic properties. The environmental analysis signifies a significant step towards a cleaner and sustainable tanning process (COD = 1600, BOD5 = 560 mg/L) compared to the conventional chrome tanning process. Consequently, the obtained results offer a green pre-tanning agent to meet the requirements of the sustainable development of the leather industry.

Immobilization of Thermomyces lanuginosus lipase in a novel polysaccharide-based hydrogel by a two-step crosslinking method and its use in the lauroylation of α-arbutin

The Thermomyces lanuginosus lipase (TLLs) was successfully immobilized within a novel hydrogel matrix through a two-step crosslinking method. TLLs were initially crosslinked through the Schiff base reaction by oxidized carboxymethyl cellulose (OCMC). The water-soluble OCMC@TLLs complex was subsequently crosslinked by carboxymethyl chitosan (CMCSH) in a microfluidic apparatus to form the CMCHS/OCMC@TLLs microspheres. The CD (Circular Dichroism, CD) and FT-IR (Fourier Transform infrared spectroscopy, FT-IR) spectra demonstrated that the crosslinking of TLLs with OCMC resulted in a less significant impact on their structure compared to that with glutaraldehyde. CMCHS/OCMC@TLLs showed decreased catalytic performance due to the mass transfer resistance, while its thermal stability was greatly improved. The CMCHS/OCMC@TLLs were used to catalyze the lauroylation of arbutin in tetrahydrofuran. After 12 h of reaction under optimal conditions, the yield of 6'-O-lauryl arbutin reached an impressive 92.12%. The prepared 6'-O-lauryl arbutin has high lipophilicity and exhibits similar tyrosinase inhibitory activity and higher antioxidant activity compared to its parent compound.

Sustained drug release behavior of captopril-incorporated chitosan/carboxymethyl cellulose biomaterials for antihypertensive therapy

Captopril (CTP) is an oral drug widely used to treat high blood pressure and congestive heart failure. In this study, CTP-incorporated biomaterials for antihypertensive therapy were synthesized from chitosan, carboxymethyl cellulose, and plasticizers. The physicochemical properties of the prepared biomaterials were characterized using FE-SEM, FT-IR analysis, and physical properties. CTP release experiments were carried out in buffer solutions at various pH values and temperatures. Results indicated that above 99.0 % of CTP was released within 180 min. Optimization of the experimental conditions for CTP release was analyzed by using response surface methodology (RSM). Results of CTP release through artificial skin indicated that CTP was continuously released above 95.0 % from the prepared biomaterials for 36.0 h. The CTP release mechanisms into a buffer and through artificial skin followed pseudo-Fickian diffusion mechanism and non-Fickian diffusion mechanisms, respectively. Moreover, angiotensin-converting enzyme (ACE) inhibition (related to cardiovascular disease) via the released CTP clearly reveals that the prepared biomaterials have a high potential as a transdermal drug delivery agent in antihypertensive therapy.

Cr (VI) and Pb (II) Removal Using Crosslinking Magnetite-Carboxymethyl Cellulose-Chitosan Hydrogel Beads

Heavy metals, such as chromium (VI) and lead (II), are the most common pollutants found in wastewater. To solve these problems, this research was intended to synthesize magnetite hydrogel beads (CMC-CS-Fe3O4) by crosslinking carboxymethyl cellulose (CMC) and chitosan (CS) and impregnating them with iron oxide (Fe3O4) as a potential adsorbent to remove Cr (VI) and Pb (II) from water. CMC-CS-Fe3O4 was characterized by pHzpc, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). Batch removal experiments with different variables (CMC:CS ratio, pH, initial metals concentration, and contact time) were conducted, and the results revealed that CMC-CS-Fe3O4 with a CMC:CS (3:1) ratio had the best adsorption capacity for Cr (VI) and Pb (II) at pH levels of 2 and 4, respectively. The findings of this research revealed that the maximum adsorption capacity for Cr (VI) and Pb (II) were 3.5 mg/g and 18.26 mg/g, respectively, within 28 h at 30 ℃. The adsorption isotherm and adsorption kinetics suggested that removal of Cr (VI) and Pb (II) were fitted to Langmuir and pseudo-second orders. The highest desorption percentages for Cr (VI) and Pb (II) were 70.43% and 83.85%, achieved using 0.3 M NaOH and 0.01 M N·a2EDTA, respectively. Interestingly, after the first cycle of the adsorption-desorption process, the hydrogel showed a sudden increase in adsorption capacity for Cr (VI) and Pb (II) until it reached 7.7 mg/g and 33.0 mg/g, respectively. This outcome may have certain causes, such as entrapped metal ions providing easy access to the available sites inside the hydrogel or thinning of the outer layer of the beads leading to greater exposure toward active sites. Hence, CMC-CS-Fe3O4 hydrogel beads may have potential application in Cr (VI) and Pb (II) removal from aqueous solutions for sustainable environments.

Multifunctional hydrogels based on oxidized pectin and gelatin for wound healing improvement

Gelatin (G) cross-linked with oxidized pectin (OP) was studied as a potential scaffold material for tissue engineering. The effect of oxidation on the chemical properties of pectin was investigated by determining the carbonyl and carboxyl amounts. The OP treatment led to a significant decrease of all values (Mn, Mw, [η] and Rh) determined by size exclusion chromatography (SEC) coupled on line with multiangle light scattering and viscometer detectors. Cross-linking parameters were elucidated by FTIR and TNBS assay. In general, the degree of crosslinking increased with the oxidation of pectin. It was found that the presence of the crosslinking agents caused a reduction in swelling and in the gelatin release which was determined by the BCA kit assay. From the hemolysis test, the membrane of red blood cells was not disrupted by the contact of films and the rate of release of hemoglobin was lower than 5%. The coagulation properties were evaluated by the dynamic blood clotting test. The G/OP hydrogels manifested a good activity of wound healing in the albino rats' model. Moreover, the films did not produce any unwilling symptoms. So, it was concluded that studied films have the potentiality to be used as wound healing biomaterials.

Preparation, characterization, release and antianemic studies of guar gum functionalized Iron complexes

Guar gum is a neutral, non-ionic polysaccharide that has been extensively utilized in the food industry as a stabilizer, excipients, and emulsifier agent. An oxidized derivative of this edible guar gum was prepared and used as a complexing agent for iron to obtain a polysaccharide-bound iron (II) complex. The degree of oxidation varies between 30.12 and 60.63% with a corresponding aldehyde content (0.59-1.79 mmol/g) and carboxyl contents (0.49-1.62 mmol/g), which were determined by the titrimetry method. Sophisticated spectroscopic techniques characterized all the products. The natural polymer-based hydrophilic and hydrophobic formulations as coating were used for achieving the sustained or prolonged release from the complex tablets. Release studies of the tablets were carried out in different mediums of varying pH. The total iron available from the tablets was compared with that obtained from ferrous fumarate prepared under similar conditions, and the results were found to be comparable. Release results demonstrate the pH-sensitive behaviour of the guar gum-based delivery system towards the controlled release of iron. Antianemic effect of new functionalized guar gum iron complexes was investigated on male albino rats. The complexes may exhibit the potential to recover the hematological index of the albino rats with some positive effects on improving rat's growth with iron deficiency anaemia.

Carboxymethyl cellulose-chitosan composite hydrogel: Modelling and experimental study of the effect of composition on microstructure and swelling response

Molecular recognition is essential for the advancement of functional supramolecular natural polymer-based hydrogels. First, a series of carboxymethyl cellulose (CMC)-chitosan (CSN) hydrogels crosslinked with fumaric acid are studied, where the influence of composition on microstructure and swelling is investigated using mathematical modelling and experiment and the hydrolytic properties, microstructure parameters and physicochemical properties are examined. Second, best fit values for the responses are obtained using multiple linear regression and MATLAB R2020a curve fitting and predictive models are generated. Third, the optimum microstructure is loaded with polyethylene glycol (PEG) and bismuth telluride (Bi₂Te₃) and coated on fabric for imparting thermal sensitivity. The results show that (1) optimum microstructure (25.65 ± 1.86 nm mesh size, 116.25 ± 0.00 μmol/cm³ effective crosslinking-density, 348.03 ± 10.81% swelling, and 62.86 ± 1.11% gel fraction) is found at CMC:CSN = 1:3 for G3; (2) the model shows good agreement with experimental data demonstrating potential for estimating hydrogel swelling and microstructure; and (3) G3/PEG and G3/PEG/Bi₂Te₃ enhance thermal conductivity of fabric at ambient, body, and elevated temperatures. The study demonstrates the potential of the generated model in predicting CMC-CSN swelling and G3 as an ideal host matrix for wearable textiles/devices.

Hydrogel Films Based on Chitosan and Oxidized Carboxymethylcellulose Optimized for the Controlled Release of Curcumin with Applications in Treating Dermatological Conditions

Cross-linked chitosan (CS) films with aldehyde groups obtained by oxidation of carboxymethyl cellulose (CMC) with NaIO4 were prepared using different molar ratios between the CHO groups from oxidized carboxymethyl cellulose (CMCOx) and NH2 groups from CS (from 0.25:1 to 2:1). Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy demonstrated the aldehyde groups' presence in the CMCOx. The maximum oxidation degree was 22.9%. In the hydrogel, the amino groups' conversion index value increased when the -CHO/-NH2 molar ratio, cross-linking temperature, and time increased, while the swelling degree values decreased. The hydrogel films were characterized by scanning electron microscopy (SEM) and FTIR analysis. The curcumin encapsulation efficiency decreases from 56.74% to 16.88% when the cross-linking degree increases. The immobilized curcumin release efficiency (REf%) and skin membrane permeability were evaluated in vitro in two different pH solutions using a Franz diffusion cell, and it was found to decrease when the molar ratio -CH=O/NH2 increases. The curcumin REf% in the receptor compartment was higher at pH = 7.4 (18%- for the sample with a molar ratio of 0.25:1) than at pH = 5.5 (16.5%). The curcumin absorption in the skin membrane at pH = 5.5 (47%) was more intense than at pH = 7.4 (8.6%). The curcumin-loaded films' antioxidant activity was improved due to the CS presence.

Experimental insight into the evolutionary mechanism of solid-to-hollow hydrogel

We for the first time disclose the evolutionary mechanism of solid-to-hollow sodium alginate (SA) hydrogel in an aqueous solution of Cu2+, H2O2 and Tris-HCl elements, where the oxidative degradation and gas bubble assistance result in the hollow structures. This provides a promising concept or method basis for the preparation of hollow hydrogels with sophisticated geometries.