Carboxyl Content Research Articles

Preparation of carboxylated-silk nanofibers by the one-pot method of maleic acid hydrolysis.

In this study, a maleic acid (MA) hydrolysis one-pot method is proposed to prepare carboxylated silk nanofibers (MA-SNFs). The MA concentration, hydrolysis temperature, and processing time were optimized. Combined with high-pressure homogenization, MA-SNFs with a carboxyl content of 0.617±0.019mmol/g and length of 333±116nm were obtained with a yield of 54.90±1.98% at the optimal conditions: 50wt% of MA concentration, 110°C of hydrolysis temperature and 120min of processing time. The morphology, chemical structure, and crystal structure of raw silk fibroin (SF), acid-hydrolyzed silk fibroin and nanofibers were studied. Furthermore, MA was reused several times with a recovery rate of >94% and maintained almost the same treatment effect. Finally, due to the presence of carboxyl groups, MA-SNF hydrogels were successfully prepared by an acetic coagulation vapor bath which exhibited excellent self-supporting ability and mechanical properties as well as a more sensitive pH response compared with regenerated silk fibroin solution and other non-carboxylated silk nanofibers. The MA-SNF aerogels had the characteristics of light weight, high strength and porous with cross-linked nanostructures.

Composition of the Low Molecular Weight Metabolome of Potamogeton perfoliatus (Potamogetonaceae) as an Indicator of the Transformation of the Ecological State of the Littoral Zone

The composition and nature of changes in the low-molecular-weight metabolome (NM) of Potamogeton perfoliatus L., growing in 6 biotopes of Lake Ladoga with different types of the anthropogenic load has been analyzed. According to the research results, it was found that the total number of low molecular weight organic compounds (LMWOCs) in the P. perfoliatus NM composition is directly dependent on anthropogenic load, which is well marked by the development of cyanobacteria. The greater the intensity of pollution or eutrophication of waters, or the higher the number of cyanobacteria, the lower the total number of LMWOCs and their concentration. A strongly pronounced dependence of the total concentrations of groups of NM compounds on the anthropogenic disturbance of the biotope and the concentration of cyanobacteria was revealed. A decrease in the number, relative amount, total concentration of carboxylic acids, number and content of unsaturated fatty acids, and, at the same time, an increase in the composition and content of phenols and the total content of aldehydes and ketones depends on an increase in anthropogenic pressure. The specific composition of NM of pierced pondweed depends on its response to biotic and abiotic factors of the aquatic environment, including anthropogenic ones. The revealed features of the change in the composition of P. perfoliatus NM make it possible to use it as an integral indicator of the anthropogenic impact on the littoral biotopes of water bodies and the deterioration of their ecological state.

Eco-friendly high microporosity low temperature plasma exposed activated carbon from coconut shell for nano hybrid supercapacitors

Abstract This study looked at the structural, chemical, and electrochemical properties of coconut shell activated carbon (CSAC) before and after plasma treatment. Structural analysis using x-ray diffraction (XRD) demonstrated that plasma treatment improves graphitic structure by plans at (002) and (101) for higher angles. Chemical investigation utilizing Fourier-transform infrared spectroscopy (FTIR) revealed an increase in hydroxyl groups and carboxylic content following plasma treatment, which enhances electrochemical performance. Raman spectroscopy revealed a drop in the ID/IG ratio from 1.00 to 0.90, indicating enhanced graphitic order. Scanning electron microscopy (FESEM) showed that plasma treatment improves surface shape, while elemental analysis assessed the high carbon content (76.56% by weight). Contact angle measurements showed a decrease from 114° to 65°, showing improved hydrophilicity after treatment. Electrochemical investigation shows that the plasma-treated CSAC had a maximum specific capacitance of 1612 F g−1, compared to 729 F g−1 for the untreated CSAC, and a total capacitance of plasma treated1685 F/g are untreated 1400 F g−1. A Type II+III pattern on the isotherms implied capillary condensation in mesopores. The plasma treatment indicated improved porosity and potential adsorption capacity by increasing the specific surface area and decreasing the average pore width. The cyclic stability tests indicated that the plasma-treated CSAC retained 94% capacitance and 98% coulombic efficiency after 3000 cycles, which is superior to the untreated CSAC’s 92% capacitance retention and 95% coulombic efficiency. This reveals that plasma-treated CSAC has significantly improved performance and stability, making it an excellent alternative for high-performance and cost-effective energy storage applications.

Highly Charged Cellulose Nanocrystals via Electrochemical Oxidation.

Due to their exceptional properties, cellulose nanocrystals (CNCs) have been proposed for various applications in sustainable materials science. However, state-of-the-art production methods suffer from low yields and rely on hazardous and environmentally harmful chemicals, representing a bottleneck for more widespread utilization of CNCs. In this study, we present a novel two-step approach that combines previously established HCl gas hydrolysis with electrochemical TEMPO oxidation. This unique method allows the collection of easily dispersible CNCs with high carboxylate contents in excellent overall yields of 71%. The electromediated oxidation was conducted in aqueous conditions without the usually required cocatalysts, simplifying the purification of the materials. Moreover, the proposed process is designed for facile recycling of the used reagents in both steps. To evaluate the sustainability and scalability, the environmental impact factor was calculated, and a cost analysis was conducted.

Fractionation of Kraft Lignin for Production of Alkyd Resins for Biobased Coatings with Oxidized Lignin Dispersants as a Co-Product.

A new valorization pathway based on solvent fractionation was applied to kraft lignin, a major by-stream of the pulping industry, to extract a soluble lignin intermediate featuring an improved structural homogeneity, a low molecular weight, and a high content of phenolic hydroxyl and carboxylic acid groups to serve as a substitute of the nonrenewable polyacids in the formulation of alkyd resins, a dominant material used in the production of anticorrosion surface coatings. Herein, softwood kraft lignin was mixed in a low-cost green solvent, aqueous ethanol, prepared at different ratios, at room temperature to generate a soluble fraction of a low M w of ≤2200 g mol-1 and an insoluble fraction of a high M w of ≥3950 g mol-1 of lignin. The best combination of yields and molecular weights of soluble lignin (16-36% yield, 1740-1890 g mol-1) was attained using 50-80 vol % ethanol in fractionation. Thus, these conditions were further employed at the pilot scale to demonstrate the scalability of this technology. Soluble lignin from pilot fractionation was used to produce an optimal alkyd resin formulation and thereafter an anticorrosion coating on the metal surface, both of which matched the target properties of industrial standards well (180 s Persoz hardness and 72 gloss units of coating, 100% adhesion of paint with no cracks or peeling in the cross-cut test, no corrosion after 120 h of the salt spray test). The insoluble solids from pilot fractionation could also be valorized by alkali-O2 oxidation into lignin-based dispersants for special carbon black pigments. Overall, this study presents a new, simple strategy to develop an efficient, scalable, low-cost, and green process for upgrading kraft lignin into phenolic intermediates for biobased alkyd resins to facilitate sustainable production of high-performance anticorrosion coatings.

Calcium Transport Activity of UV/H2O2-Degraded Fucoidans and Their Structural Characterization.

Calcium-chelated polysaccharides have been increasingly considered as promising calcium supplements. In this study, degraded fucoidans (DFs) with different molecular weights (Mws) were prepared after UV/H2O2 treatment; their calcium-chelating capacities and intestinal absorption properties were also investigated. The results showed that the calcium-chelating capacities of DFs were improved with a decrease in Mw. This was mainly ascribed to the increased carboxyl content, which was caused by free-radical-mediated degradation. Meanwhile, the conformation of DF changed from a rod-like chain to a shorter and softer chain. The thermodynamic analysis demonstrated that DF binding to calcium was spontaneously driven by electrostatic interactions. Additionally, DF-Ca chelates with lower Mw showed favorable transport properties across a Caco-2 cell monolayer and could effectively accelerate the calcium influx through intestinal enterocytes. Furthermore, these chelates also exhibited a protective effect on the epithelial barrier by alleviating damage to tight junction proteins. These findings provide an effective free-radical-related approach for the development of polysaccharide-based calcium supplements with improved intestinal calcium transport ability.

Effects of photooxidation exposure time on the modification of cassava starch: a comprehensive study on chemical, functional, structural, and morphological properties

Photooxidation is one of the green technologies that can be used to modify starch. This process produces oxidized starch which induces alterations in the starch structure and functional properties. Photooxidation of starch can be influenced by hydrogen peroxide concentration, exposure time, slurry concentration, ultraviolet (UV) intensity, addition of lactic acid, and temperature. This study aims to evaluate the effect of photooxidation exposure time on the chemical, functional, structural, and morphological properties of cassava starch. Cassava starch was modified using a UV catalysator reactor and treated with photooxidation using a combination of hydrogen peroxide and UV irradiation for 15, 30, and 45 min. The result showed that the longer exposure time produced starch with higher amylose, carboxyl contents, solubility, water absorption capacity, oil absorption capacity, and color L*. Moreover, the longer time of the photooxidation process caused a decrease in the pH value, swelling power, and pasting properties. Photooxidation decreased the relative crystallinity values and damaged the granule morphology of the modified cassava starch. These results showed that photooxidation successfully modified cassava starch.

Citric acid crosslinked hydroxyethyl tamarind gum-based hydrogel films: A promising biomaterial for drug delivery

This investigation explored citric acid crosslinked hydroxyethyl tamarind gum hydrogel films as a potential biomaterial for drug delivery. Hydroxyethylation of tamarind gum aimed to improve its solubility, swelling, and crosslinking potential. The synthesized hydroxyethylated tamarind gum (HETG) was comprehensively characterized, revealing the presence of hydroxyethyl groups and increased viscosity in comparison to unmodified tamarind gum. The citric acid crosslinked HETG hydrogel films were developed by esterification-crosslinking mechanism. The films were characterized using instrumental techniques and evaluated for total carboxyl content, mechanical properties, swelling behavior, drug loading, drug release, antibacterial activity, hemocompatibility and in vitro wound healing activity. The presence of ester crosslinks and extent of crosslinking was confirmed through total carboxyl content and instrumental analysis. Varying HETG (2–2.5%w/v) and citric acid (1–1.4 %w/v) concentrations resulted in films with tunable mechanical strength, swelling, and drug loading. The films effectively controlled the release of a water-soluble drug (80.87–99.70 % in 24 h) through a non-Fickian diffusion mechanism. The optimized HETG hydrogel film showed antimicrobial activity, hemocompatibility, and support for cell growth, confirming its biocompatibility and potential for wound healing. Citric acid-crosslinked HETG films appear promising for drug delivery to wounds, meriting further in vivo study.

Synthesis of Carboxylate-Dialdehyde Cellulose to Use as a Component in Composite Thin Films for an Antibacterial Material in Wound Dressing.

Wound infections can lead to life-threatening infection and death. Antibacterial materials from biopolymers in the form of films are a promising strategy for wound dressings. Carboxylate-dialdehyde cellulose (CDAC) is a proper candidate for use as an antibacterial material due to its biocompatibility, nontoxicity, and antibacterial property. Additionally, CDAC can be synthesized from cellulose through environmentally friendly and nontoxic methods. Thus, this study aims to synthesize CDAC from microcrystalline cellulose (MCC) PH102 and use it in composite films for an antibacterial application. The CDAC was synthesized using Fe2+/H2O2, followed by NaIO4 oxidation. The obtained CDAC was characterized in terms of carboxylate and aldehyde content as well as FTIR and XRD spectra. The CDAC was mixed with HPMC in different ratios to prepare films. To determine the optimal formulation for clindamycin HCl loading, the films were evaluated for morphology, mechanical properties, and swelling ratio. Finally, the films containing clindamycin HCl were evaluated for drug loading content, in vitro drug release, and antibacterial activity. This study found that CDAC contained 2.1 ± 0.2 carboxylate and 4.15 ± 0.2 mmol/g of aldehyde content. The FTIR spectra confirmed the successful synthesis. X-ray diffractograms indicated that CDAC was less crystalline than MCC. The film, consisting of CDAC and HPMC E50 in the ratio of 2:1 (D2H1), was identified as the most suitable for clindamycin HCl loading due to its superior appearance, mechanical strength, and swelling properties compared to other formulations. D2H1 exhibited a high drug loading capacity (91.49 ± 5.48%) and demonstrated faster drug release than the film composed only of HPMC because of the higher swelling ratio and lower mechanical strength. This formulation was effective against Staphylococcus aureus (MSSA), S. aureus (MRSA), and Pseudomonas aeruginosa. Furthermore, the D2H1 film containing clindamycin HCl showed a larger inhibition zone against these bacteria, likely due to a synergistic effect. This study found that CDAC has the potential to be applied as an antibacterial material for wound dressing.

PFAS Exposure is Associated with a Lower Spermatic Quality in an Arctic Seabird.

Several studies have reported an increasing occurrence of poly- and perfluorinated alkyl substances (PFASs) in Arctic wildlife tissues, raising concerns due to their resistance to degradation. While some research has explored PFAS's physiological effects on birds, their impact on reproductive functions, particularly sperm quality, remains underexplored. This study aims to assess (1) potential association between PFAS concentrations in blood and sperm quality in black-legged kittiwakes (Rissa tridactyla), focusing on the percentage of abnormal spermatozoa, sperm velocity, percentage of sperm motility, and morphology; and (2) examine the association of plasma levels of testosterone, corticosterone, and luteinizing hormone with both PFAS concentrations and sperm quality parameters to assess possible endocrine disrupting pathways. Our findings reveal a positive correlation between the concentration of longer-chain perfluoroalkyl carboxylates (PFCA; C11-C14) in blood and the percentage of abnormal sperm in kittiwakes. Additionally, we observed that two other PFAS (i.e., PFOSlin and PFNA), distinct from those associated with sperm abnormalities, were positively correlated with the stress hormone corticosterone. These findings emphasize the potentially harmful substance-specific effects of long-chain PFCAs on seabirds and the need for further research into the impact of pollutants on sperm quality as a potential additional detrimental effect on birds.

Biobased amphoteric aerogel with core-shell structure for the hierarchically efficient adsorption of anionic and cationic dyes

Efficient and simultaneous removal of anionic and cationic dyes from wastewater using low-cost and environmentally-friendly adsorbent is highly required. Herein, the carboxylated cellulose (carboxyl content: 2.97 mmol/g) derived from pomelo peel was extracted by a one-step H2O2/H2SO4-mediated oxidation method. Subsequently, a novel pomelo-peel cellulose/chitosan/sodium alginate (PCS) amphoteric aerogel with a specific core-shell structure was synthesized by multiple physical cross-linking strategies. The shell layer and core layer of the optimized P3CS0.75 aerogel can selectively adsorb cationic dyes and anionic dyes, in which, the theoretical maximum adsorption capacities were 888.27 mg/g and 1816.87 mg/g towards methylene blue (MB) and Congo red (CR), respectively. Especially, the aerogel’s core/shell layer exhibited hierarchical adsorption behavior without overlapping sites even in the binary dye systems. The adsorption performance of obtained amphoteric aerogel remained effective in a wide pH range and under different practical water systems. Moreover, the removal efficiencies for MB and CR were slightly reduced from 90.76 % and 99.66 % to 88.08 % and 91.39 %, respectively, after 5 adsorption-desorption cycles, and the aerogel’s structural integrity was also maintained due to its good compressive strength (487.16 KPa). In addition, the adsorption mechanism of PCS aerogel was investigated using adsorption kinetics, isotherm, thermodynamics, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. It was proved that the adsorption process was endothermic spontaneous-monolayer adsorption driven by electrostatic attraction and hydrogen bonding. Therefore, the prepared biobased aerogel was expected to be a prospective material for removing mixed dyes from wastewater.

Dual modification of starch: Synergistic effects of ozonation and pulsed electric fields on structural, rheological, and functional attributes

Study evaluated the influence of ozonization (O3) time combined with pulsed electric fields (PEF) on the modification of bean starch structure. O₃ was used at a concentration of 0.045 g/L for 60 min (Oz1) and 120 min (Oz2) both individually and in combination with 30 kV/cm (P30). Carbonyl content was higher than the carboxyl content, especially with prolonged treatment times (Oz2), indicating partial oxidation. Additionally, higher levels of amylose and degrees of polymerization (DP ≥ 37 and DP 25–36) were observed in the oxidized starches, with significant changes only when combined with PEF. The main morphological and structural modifications included the presence of agglomerates, partial gelatinization, reduced crystallinity, and lower IR1047/1022 in the granules treated with PEF + O3. Oxidized starches exhibited higher solubility, resulting in lower values for rheological parameters, with PEF + 2 h of O3 (Oz2P) standing out. It can be used as prebiotics, controlled release agents and a texturizer for gluten-free foods.

Effect of catalyst and oxidant concentrations in a TEMPO oxidation system on the production of cellulose nanofibers.

In traditional TEMPO oxidation systems, the high cost of TEMPO catalysts has been a significant barrier to the industrialization of oxidized CNF. From an economic perspective, presenting the characteristics of various CNFs produced with the oxidation systems with reduced catalyst usage could facilitate the industrial application of CNF across a wide range of fields. In this study, it was demonstrated that reducing the amount of TEMPO catalyst used (from 0.1 to 0.05 mmol g-1) in a conventional oxidation system increased the carboxylate content by approximately 6.3%. Furthermore, the activation of hydroxyl amine TEMPO, which is generated after the oxidation reaction of cellulose, was enhanced by adjusting the dosage of the inexpensive oxidant NaClO, leading to a 20% improvement in carboxylate content. This suggests that controlling the amount of NaClO as an oxidant can be a key parameter in adjusting the dosage of TEMPO to achieve the targeted degree of surface substitution. Results from the dispersion stability, UV-transmittance, and morphological properties of TEMPO-oxidized CNF using microfluidizing treatment showed that high carboxylate content plays a crucial role in producing high-purity CNF suspensions, which are small, uniform, and free from microfibers. Additionally, by varying the number of mechanical treatments applied to the oxidized cellulose, various types of CNF suspensions with different mean widths were obtained. We expect that these findings offer meaningful insights to end-users seeking a breakthrough in the performance limitations of final applications using cellulose nanomaterials.

Facile Synthesis and Characterization of Fluorescent Polystyrene Nanospheres for Homogeneous Light-Initiated Chemiluminescence Immunoassay.

Homogeneous light-initiated chemiluminescence technology (LICA) is widely used in clinical diagnostics due to the advantages of high sensitivity, minimal reagent usage, and no need for washing. Luminescent microspheres receive singlet oxygen emitted by photosensitive microspheres to generate optical signals. Therefore,1O2-initiated luminescent nanospheres are crucial, but there are few reports on the preparation of 1O2-initiated luminescent nanospheres. Herein, monodisperse luminescent Eu/C-28@PS (Eps) nanospheres were prepared and optimized using chelate Eu (TTA)3phen and 4-(2-phenyl-5,6-dihydro1,4-oxathiin-3-yl)-N, N-ditetradecylbenzenamine (C-28) as probe dye via THF/water swelling-shrinking procedure. Various swelling parameters were studied to obtain the swelling conditions that produce the minimum particle size and narrow size distribution, which shows good results in uniform particle size distribution (~ 250nm, a PDI of 0.03), surface carboxylate content (1.18mmol/g), and BSA loading capability (129.8mg/g) in the case of 20mg total probe dosage and 2h of incubation at 40°C using 14% THF/water mixture as a co-solvent system. The composition of the entrapped probe has a gain effect on the 1O2-initiated fluorescent signal and the optimal ratio of Eu (TTA)3phen: C-28 (1:1) was obtained on a commercial analyzer using IgG and anti-human IgG as models in PBS buffer. These results indicate that monodisperse luminescent Eps nanospheres are suitable as light-initiated chemiluminescence sensors and have great application potential in early detection, screening tests, and prognostic evaluation of patients.

Valorization of water hyacinth: Efficient extraction of nanofibrillated crystals using ultrasound-assisted TEMPO oxidation and their application in flexible piezoelectric films

This study presents an efficient extraction of nanocellulose crystals (CNCs) and nanofibers (CNFs) through ultrasound-assisted TEMPO oxidation method using deep-processed heavy metal-containing calabash as raw material. The extraction method, integrating TEMPO-mediated oxidation and ultrasound techniques, enhanced the yield of CNCs and CNFs. The results demonstrate that CNCs yielded 63 %, with a carboxyl content of 1.27 mmol/g, while CNFs yielded 31 %, with a carboxyl content of 1.21 mmol/g. CNCs and CNFs exhibited excellent mechanical properties, with CNCs having an average length of 214.4 nm, average diameter of 2.72 nm, and a length-to-diameter ratio of 78.8. CNFs had an average length of 437.8 nm, average diameter of 5.7 nm, and a length-to-diameter ratio of 76.8. X-ray diffraction (XRD) results showed crystallinity of 87.1 % for CNCs and 81.2 % for CNFs. The thermal stability of the fibers was confirmed up to 230℃. The film prepared by combining 10 % PVA with 90 % CNC exhibited a tensile strength of 32.11 MPa, Young's modulus of 2027.1 MPa, and could generate a maximum voltage of 0.83 V. This study provides an effective pathway for the value-added utilization of deep-processed calabash and highlights the broad application prospects of the composite film in the field of flexible sensors.

Effect of carbodiimides on the compatibility and hydrolytic behavior of PLA/PBAT blends

Blends of polylactic acid (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) have great potential to replace conventional polyolefin and polyester materials. However, poor compatibility and fast degradation rate limit its development. In this paper, the effects of two monomer-type carbodiimides and one polymerized carbodiimide on the crystalline, thermal stability, hydrolysis properties, and mechanical properties of PLA/PBAT blends are investigated by Fourier transform infrared spectroscopy, scanning electron microscope, differential scanning calorimetry, thermogravimetric analysis, gel permeation chromatography, melt mass-flow rate, terminal carboxyl content, tensile properties, and rotational torque. It is found that all the three carbodiimide additives can improve the compatibility and enhance the mechanical, processing, and thermal stability properties of PLA/PBAT blends except for their reduced crystallization performance. Moreover, regarding the hydrolysis properties, the two monomeric carbodiimides exhibit little effect on the hydrolysis of PLA/PBAT blends, even accelerating the degradation rate under alkaline conditions. However, the antihydrolysis effect of polycarbodiimide is remarkable, which effectively improves the compatibility and antihydrolysis properties of PLA/PBAT blends.

Achievement of biochar photocatalytic performance by synergistic oxidation of sulfuric acid/hydrogen peroxide: Towards revealing the mechanism of synergistic oxidation on photocatalytic performance

The oxygen-containing functional groups of biochar have great potential in tailoring photochemical properties, but the content of oxygen-containing functional groups of pristine biochar is insufficient to support photocatalytic reactions. In this study, a synergistic oxidation of H2SO4 and H2O2 was innovatively proposed to prepare biochar photocatalysts (OGPC400). The results showed that the synergistic oxidation of H2SO4 and H2O2 increased the contents of hydroxyl and carboxyl groups of biochar with the degree of oxidation, and the total concentration of acidic functional groups was about 4 mmol/g higher than that of the oxidation with H2SO4 or H2O2 alone, which was attributed to the synergistic oxidation to promote the conversion of CH and C-OH on the benzene ring. The achievement of electron exchange among hydroxyl and carboxyl groups and internal electron transfer within biochar by the benzene ring as a medium resulted in 100 % degradation of rhodamine b (RhB) and 25 times reaction rate constant higher than that of pristine biochar, as compared to only 45 % or 37 % degradation by oxidation with H2SO4 or H2O2 alone. The exciting results confirmed the positive availability of H2SO4 and H2O2 synergistic oxidation on biochar photocatalysts, which is expected to be applied in environmental remediation.

Liquid carboxylated nitrile butadiene rubber via metathetic degradation with acrylic acid as chain transfer agent

Liquid carboxylated nitrile butadiene rubber (LXNBR) shows promising application in various fields. Facing the challenges in its preparation via radical emulsion copolymerization, such as gelation, molecular weight and carboxyl group content, novel approach has been developed for the controlled preparation of LXNBR via the metathetic degradation of nitrile butadiene rubber (NBR) with acrylic acid (AA) as chain transfer agent (CTA). Based on the molecular weight and carboxyl group content of the resultant products, the reaction pathway was proposed. Such understanding is expected to prepare LXNBR with designed Mn and carboxyl group content for various applications, by facile adjusting the reaction condition, mainly the feeding mode of AA, NBR concentration and reaction time.

Bioactive matrix scaffold of oxidized sacchachitin via green catalyst of siliacat tempo for enhancing bone regeneration

Bone regeneration remains a critical challenge in orthopedic medicine. Extracellular matrix proteins play important roles in bionic mineralization and osteogenesis. Sacchachitin nanofibers (SCNFs) oxidized via TEMPO have shown great potential as biomaterial scaffolds due to the introduction of carboxylic groups that mimic the natural extracellular matrix. However, TEMPO is harmful to the environment, which calls for greener and sustainable alternatives. Therefore, this study explored the green fabrication of oxidized-SCNFs through SiliaCat-TEMPO (STEMPO) as a renewable catalyst with various amount of oxidation agents to evaluate their bone regeneration ability. We developed an optimal STEMPO oxidation process, enabling efficient removal of most STEMPO particles through centrifugation with minimal residue. The oxidation efficiency of recovered STEMPO particles remained comparable to fresh ones. STEMPO-oxidized SCNFs, oxidized at increasing NaClO levels, showed an increase in carboxylate content, from 0.1360 mmol/g to 3.2415 mmol/g. Additionally, STEMPO-oxidized SCNFs exhibited excellent biocompatibility with MC3T3-E1 osteoblastic cells, facilitating calcium precipitation, cell migration, and osteogenic differentiation. Mixed composites of β-tricalcium phosphate (BCP) and STEMPO-oxidized SCNFs with higher oxidation levels further enhanced osteogenic differentiation. In vivo studies using a rat femur defect model showed that SCNFs at the highest oxidation level (ST100SC) significantly promoted bone regeneration to full recovery, achieving a bone volume to total tissue volume (BV/TV) ratio of 75.6 %, compared to 48.3 % in the control. These results demonstrated that STEMPO-oxidized SCNFs with higher oxidation levels can be used as a bioactive matrix scaffold to achieve full recovery of bone regeneration.

Biopolymer-containing formulations to render acrylic fabrics fire resistant and anti-static

Although widely used in textile applications, acrylic fabric (AF) suffers from being hydrophobic, with a surface that has a high tendency to catch fire and create electrostatic charge. Many methods have been adopted to improve the performance attributes of AF; however, theyare either polluting or not durable against repeated washing. Herein, a synergy of phytic acid (PA) and a protein biopolymer, namely keratin or sericin, was adopted to boost the resistance to flame, ultraviolet rays, and electrostatic charges, as well as enhance the hydrophilicity of AF. An efficient flame retardant (FR) was synthesized by reacting calculated amounts of PA and pentaerythritol (PE) to form hexa-pentaerythritolphytate ester (HPP), which in turn reacted with a proteinic biopolymer in the presence or absence of a crosslinking agent to produce a multifunctional FR formulation. The prepared formulation was utilized as a multifunctional textile auxiliary for improving the resistance of alkali-hydrolyzed AF to flame and UV rays and for enhancing its hydrophilic and anti-static properties. The chemical structure of the synthesized functional FR was investigated using FTIR and by determining its phosphorus, nitrogen, and carboxylic contents. The mechanism of reaction between the synthesized FR and the hydrolyzed fabric was proposed. The discrepancy between the topographies of the treated and untreated fabrics was monitored using scanning electron microscopy. The results revealed that the treated AF exhibited a durable and superior resistance to flame, which was not adversely affected by washing up to 20 times. The anti-static property and wettability of the treated fabrics were highly improved, whereas their resistance to the deteriorative action of UV rays was enhanced to an almost an adequate level according to AS/NZS 4399:1996. The proposed process is an additive method for improving some performance and comfort attributes of AF without causing a severe loss in the fabric’s strength.