Gel Fraction Research Articles

Facile preparation of zirconium(IV) immobilized carboxymethyl cellulose/multiwalled carbon nanotubes gels by radiation technique and its selective fluoride removal

Removal of excessive fluorine in the waterbody environment and the Zn hydrometallurgical system is an urgent problem. In this paper, zirconium oxychloride immobilized carboxymethyl cellulose/carboxymethyl multiwalled carbon nanotube (CMC+MWCCNT-ZrOCl2) gels are facilely prepared by radiation technique. The addition of MWCCNT endows the CMC-ZrOCl2 gel a typical nanotubes/fiber structure, also increase the gel fraction of the gel. The selective adsorption of fluoride from single or co-existed anions was investigated. The adsorption isotherms can be well fitted by both the Langmuir and Freundlich model. The calculated maximum adsorption capacity was 36.657 mg/g. The selectivity coefficients of CMC+MWCCNT-ZrOCl2 for fluoride versus NO3−, PO43−, and SO42− are 140.34, 10.953, and 72.572, respectively. Also, CMC+MWCCNT-ZrOCl2 can be used as a potential adsorbent for selective removing F− from high concentration SO42− solution. The adsorption mechanism was investigated by XPS analyses.

Exploring the potential of a pH-sensitive hydrogel sponge: interpenetrating network of tragacanth and pectin for controlled delivery of levosulpiride.

The development of drug delivery systems that allow precise control over drug release pattern has fetched significant attention in the pharmaceutical field. This research work investigates the potential of a pH-sensitive interpenetrating network (IPN) composed of tragacanth and pectin as a carrier for the controlled release of levosulpiride. To enhance the solubility of poorly soluble drug levosulpiride, inclusion complexes were formed with beta cyclodextrin (βCD). The IPN was prepared by cross-linking tragacanth with pectin by adopting a green chemistry approach. The resulting cross-linked polymeric network was subjected to repetitive freeze-drying cycles for preparation of spongy mass. The physicochemical properties of the resultant product were thoroughly characterized using a range of analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal analyses (DSC/TGA), and X-ray diffraction (XRD). The physical parameters like sol-gel fraction (%), drug loading (%), swelling behavior, electrolyte responsiveness, and in vitro drug release profile of the developed sponge were systematically evaluated under varying pH conditions. Results of FTIR demonstrated the formation of cross-linked network, ruling out drug-excipient interaction. SEM analysis unveiled porous and rough geometry. Thermal analyses proved the hydrogel network thermally stable whereas, PXRD demonstrated the overall amorphous nature of the hydrogel sponge. The outcomes of physical parameters demonstrated an incremental trend in gel fraction from 63 to 85% on raising the molar concentration of cross-linker from TP1 to TP3. However, increasing tragacanth content escalation in gel fraction from 75 to 79% was noticed. While gel fraction was augmented from 79 to 83% with increasing pectin contents. The maximum drug loading formulation TP3 was computed to be 89%. Hydrogel sponges also demonstrated electrolyte responsiveness. The release profile indicated a pH-responsive behavior, with sustained release up to 10h observed in a buffer solution of pH 6.8 and 7.4. In an acidic medium, a minor amount of drug was released during 10h dissolution. Drug release kinetics was observed to be in zero order. The findings of this study highlight the promising potential of the tragacanth/pectin hydrogel sponge as a pH-sensitive dais for the controlled delivery of levosulpiride, emphasizing its potential application in personalized drug therapy and the treatment of gastrointestinal disorders.

Development of Antioxidant-Active Sericin-Curcumin-Loaded Sodium Alginate/Polyvinyl Alcohol Films Crosslinked with Calcium Chloride as a Promising Wound Dressing Application.

Silk sericin (SS) and curcumin (Cur) possess significant antioxidant properties, making them highly beneficial for wound healing applications. This study aimed to develop SS-Cur-loaded sodium alginate/polyvinyl alcohol (SA/PVA) films crosslinked with calcium chloride, creating a biomaterial with enhanced stability and antioxidant properties. Wound dressings containing SS-Cur were fabricated by mixing SA and PVA at different ratios of 1:1, 1:2, 1:4, and 1:6. The resulting films were then crosslinked with calcium chloride in an ethanol solution to enhance film integrity. These films were characterized using several techniques, revealing that the presence of ethanol in calcium chloride affected film properties, including the gel fraction, swelling, film thickness, and FTIR analysis. The presence of ethanol in calcium chloride revealed the highest drug content in the SA/PVA films. In vitro release studies demonstrated sustained release of SS-Cur from all formulations. Cytotoxicity and antioxidant activity tests showed that SS-Cur-loaded SA/PVA films with ethanol in calcium chloride increased cell viability and enhanced antioxidant effects in L929 cells. In conclusion, this study demonstrates that the presence of ethanol in the crosslinking solution improved the functionality of SS-Cur-loaded SA/PVA films, making them promising candidates for wound healing and soft tissue regeneration.

Circular Cross-Linked Polyethylene Enabled by In-Chain Ketones.

Cross-linked polyethylenes (PEs) are widely employed, but the permanent links between the chains impede recycling. We show that via imine formation with diamines keto-functionalized polyethylenes from both free-radical (keto-low-density PE, keto-LDPE) and catalytic (keto-high-density PE, keto-HDPE) nonalternating ethylene-CO copolymerization can be cross-linked efficiently in the melt, resulting in gel fractions of the formed cross-linked PEs of up to 85% and improved tensile properties. The imine-based cross-links in the material can be hydrolyzed at 140 °C to recycle up to 97% of the initial thermoplastic keto-polyethylene. Low keto contents of ≤1.5 mol % are found ideal to retain PE-like thermal properties, achieve sufficient cross-link density, and maintain circular recyclability.

Novel antimicrobial biodegradable composite films as packaging materials based on shellac/chitosan, and ZnAl2O4 or CuAl2O4 spinel nanoparticles

ZnAl2O4 and CuAl2O4 spinel nanoparticles were prepared by a modified Pechini method and used with the natural chitosan (CS) and shellac (SH) polymers to form novel composite membranes as promising food packaging materials. The selection of ZnAl2O4 and CuAl2O4 spinel nanoparticles was based on their antibacterial characteristics, availability, and economy. Using a straightforward and adaptable solution mixing and casting method, the bio-composites were created. The mechanical, physical, antibacterial, homogeneity and air permeability properties of composite films were investigated. The film structure was evaluated in terms of component interactions using FTIR spectra. The addition of 10% SH increased the tensile strength, percentage strain at maximum load, Young’s modulus, and burst strength by 114–101%, 3.6–8.4, 103–119, and 179–153% for low and middle M.wt./CS respectively. Chitosan/shellac-CuAl2O4 composite has superior properties compared to ZnAl2O4 composite. In general, 0.05% spinel provides a composite having better qualities than that of 0.1 additions. Middle M.wt. chitosan provides a composite with superior properties compared to that of low M.wt. The incorporation of ZnAl2O4 or CuAl2O4 enhanced the thermal stability of the SH/CS composite. ZnAl2O4 provides superior thermal stability than CuAl2O4. When shellac/CS film structure is treated with the previously indicated ZnAl2O4 or CuAl2O4 formulation, the % swelling decreases along with an increasing in the gel fraction. The antimicrobial assessment using inhibition zone diameter and shake flask methods showed that a composite of 1:9 shellac/chitosan/0.05% of CuAl2O4 exerted the highest Gram-positive antibacterial activity against B. mycoides (21 mm), and C. albicans (22 mm). So, these enhancements make chitosan/shellac/ZnAl2O4 or CuAl2O4 composite films a good alternative to producing food packaging materials.

The Role of Freeze-Drying as a Multifunctional Process in Improving the Properties of Hydrogels for Medical Use.

Background/Objectives: Freeze-drying is a dehydration method that extends the shelf life and stability of drugs, vaccines, and biologics. Recently, its role has expanded beyond preservation to improve novel pharmaceuticals and their carriers, such as hydrogels, which are widely studied for both drug delivery and wound healing. The main aim of this study was to explore the multifunctional role of freeze-drying in improving the physicochemical properties of sodium alginate/poly(vinyl alcohol)-based hydrogels for medical applications. Methods: The base matrix and hydrogels containing a nanocarrier-drug system, were prepared by chemical cross-linking and then freeze-dried for 24 h at -53 °C under 0.2 mBa. Key analyses included determination of gel fraction, swelling ratio, FT-IR, SEM, TG/DTG, in vitro drug release and kinetics, and cytotoxicity assessment. Results: Freeze-drying caused an increase in the gel fraction of the hydrogel with the dual drug delivery system from 55 ± 1.6% to 72 ± 0.5%. Swelling ability was pH-dependent and remained in the same range (175-282%). Thermogravimetric analysis showed that freeze-dried hydrogels exhibited higher thermal stability than their non-freeze-dried equivalents. The temperature at 10% weight loss increased from 194.0 °C to 198.9 °C for the freeze-dried drug-loaded matrix, and from 188.4 °C to 203.1 °C for the freeze-dried drug-free matrix. The average pore size of the freeze-dried hydrogels was in the range of 1.07 µm ± 0.54 to 1.74 µm ± 0.92. In vitro drug release revealed that active substances were released in a controlled and prolonged way, according to the Korsmeyer-Peppas model. The cumulative amount of salicylic acid released at pH = 9.0 after 96 h was 63%, while that of fluocinolone acetonide reached 73%. Both hydrogels were non-toxic to human fibroblast cells, maintaining over 90% cell viability after 48 h of incubation. Conclusions: The results show a high potential for commercialisation of the obtained hydrogels as medical dressings.

Efficient Cross-Linking through C-H Bond Insertion of Unfunctionalized Commodity Materials Using Diazirine-Containing Polymers.

The synthesis and application of multifunctional diazirine-containing polymers for on-demand cross-linking of unfunctionalized commodity polymers through C-H bond insertion is demonstrated. While small-molecule diazirine cross-linkers have seen important applications such as plastic compatibilization and photopatterning, the high degree of functionalization of polymer-based diazirine cross-linkers offers promise for enhanced compatibility based on polymer blending and increased efficiency due to controllable multivalency. As a demonstrative example, unfunctionalized linear poly(n-butyl acrylate) (PnBA) can be cross-linked using various polymeric cross-linkers with diazirine contents as low as 0.8 wt % in 1 min under photochemical conditions. With gel fractions up to 95%, tunable rheological behavior is observed with increasing cross-linker loadings, consistent with a transition from entangled branched polymers to a cross-linked network. Moreover, the synthetic stability of the diazirine units can be exploited to prepare diazirine-containing polymers based on a variety of different backbones, from vinyl copolymers to poly(dimethylsiloxane) (PDMS), which allows successful photopatterning using a commercial 3D printer.

Biodegradable genipin cross-linked chitosan/pea protein isolate sponges for effective adsorption of methyl blue: Batch experiments and quantum chemical analysis

This study successfully prepared double crosslinked chitosan (CS) and pea protein isolate (PPI) composite sponges using genipin as a crosslinking agent and investigated their effectiveness as an adsorbent for methyl blue (MEB) in aqueous solutions. The composite sponges were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller measurement, swelling tests, gel fraction measurement, zeta potential, and X-ray diffraction. Additionally, the effects of genipin content, pea protein isolate content, sponge dosage, initial pH of the solution, adsorption time, dye concentration, and adsorption temperature on dye removal ability were studied. The results showed that at pH 3.0 and a dye concentration of 100 mg/L, the adsorption capacity of the sponge for methyl blue was found to be 351.6 mg/g. At 298 K and after 720 min, with a dye concentration of 700 mg/L, the maximum adsorption capacity of the sponge for methyl blue reached 959.3 mg/g. The adsorption process follows a pseudo-second-order kinetic model and a Langmuir isotherm. Theoretical analysis using density functional theory suggests that the adsorption of methyl blue by the composite sponge is attributed to the anionic sulfonic acid group of the dye. The composite sponge degraded 76.1 % after being buried in soil for 21 days. This study reveals the enormous potential of biodegradable chitosan-protein-based sponges in effectively removing methyl blue dye pollutants from wastewater.

Optimization, experimental and theoretical investigation of modified guar-gum and poly(acrylic acid) based smart hydrogel for controlled release applications in the agricultural field

A series of smart polymer hydrogels with good uptake and controlled release characteristics were synthesized free-radically by growing poly(acrylic acid) on allylated guar gum using ammonium persulfate as an initiator and trimethylolpropane triacrylate as the crosslinker. The synthesized hydrogels were evaluated using FT-IR and NMR for their structure, thermo-gravimetric analysis (TG) to measure thermal stability, and scanning electron microscopy (SEM) to analyze surface morphology and swellability by gravimetric method under different pH and temperature conditions. The soil moisture content and gel fractions were measured using gravimetric methods. Additionally, a theoretical investigation was also performed to assess the urea-holding capacity of the synthesized hydrogel matrix using density functional theory (DFT) calculations. The uptake study revealed that the hydrogel with optimized monomer feed composition absorbed 851 g/g of water, 78 % and 67 % of urea from 0.5 % and 1 % urea solutions respectively under ambient conditions. The release study showed that 56 and 47 % of absorbed urea were released over 15 days from the urea-loaded hydrogels (0.5 % and 1 % urea solutions respectively). The uptake mechanism obeyed the non-Fickian and first-order kinetics models. The experimental evaluation and DFT calculations conveyed that the synthesized hydrogel could act as a candidature matrix for the controlled release of water and fertilizer in the agricultural field.

Hydrogel Containing Propolis: Physical Characterization and Evaluation of Biological Activities for Potential Use in the Treatment of Skin Lesions.

Skin injury affects the integrity of the skin structure and induces the wound healing process, which is defined by a well-coordinated series of cellular and molecular reactions that aim to recover or replace the injured tissue. Hydrogels are a group of promising biomaterials that are able to incorporate active ingredients for use as dressings. This study aimed to synthesize hydrogels with and without propolis extract and evaluate their physical characteristics and biological activities in vitro for potential use as active dressings in the treatment of skin lesions. The antifungal [Candida albicans (C. albicans) and Candida tropicalis (C. tropicalis)] and antibacterial [Staphylococcus aureus (S. aureus), Pseudomonas aeruginosas (P. aeruginosas) and Escherichia coli (E. coli)] activity was assessed by the microdilution method in plates and antioxidant potential by the reduction of the phosphomolybdate complex. The hydrogels showed good water absorption capacity, high solubility, and high gel fraction, as well as good porosity, water retention, and vapor transmission rates. They revealed a totally amorphous structure. The extract and the hydrogels containing the propolis extract (1.0% and 2.5%) did not inhibit fungal growth. However, they showed antibacterial activity against strains of S. aureus and P. aeruginosas. Regarding the E. coli strain, only the extract inhibited its growth. It showed good antioxidant activity by the evaluation method used. Therefore, the hydrogels containing propolis extract can be a promising alternative with antibacterial and antioxidant action for use as dressings for the treatment of skin lesions.

Bio-Based Self-Healing Epoxy Vitrimers with Dynamic Imine and Disulfide Bonds Derived from Vanillin, Cystamine, and Dimer Diamine.

The condensation reactions of 4,4'-(ethane-1,2-diylbis (oxy)) bis(3-methoxybenzaldehyde) (VV) with cystamine, 1,6-hexamenthylene diamine, and a dimer diamine (PriamineTM 1075) produced three types of vanillin-derived imine-and disulfide-containing diamines (VC, VH, and VD, respectively). Thermal curing reactions of polyglycerol polyglycidyl ether with VD and mixtures of VC/VD and VH/VD produced bio-based epoxy vitrimers (BEV-VD, BEV-VC/VD, and BEV-VH/VD, respectively). The degree of swelling and gel fraction tests revealed the formation of a network structure, and the crosslinking density increased with a decreasing VD fraction. The glass transition temperature, tensile strength, and tensile modulus of the cured films increased as the VD fraction decreased. In contrast, the thermal degradation temperature of the cured films increased as the VD fraction increased. All the cured films were healed by hot pressing at 120 °C for 2 h under 1 MPa at least three times. The healing efficiencies, based on tensile strength after the first healing treatment, were 75-78%, which gradually decreased as the healing cycle was repeated. When imine-and disulfide-containing BEV-VC/VD and imine-containing BEV-VH/VD with the same VC/VD and VH/VD ratios were used, the former exhibited a slightly higher healing efficiency.

Reversible Vitrimisation of Single‐Use Plastics and their Mixtures

AbstractVitrimers are promising next‐generation materials, often exhibiting superior properties such as mechanical strength and solvent resistance compared to their thermoplastic counterparts, while still featuring recyclability due to their dynamic covalent crosslinks. The most common strategy to recycle vitrimers is via mechanical reprocessing at high temperatures, while others utilize chemical degradation to reobtain the constituent monomers. This work presents a new approach toward reprocessing by selectively breaking of the vitrimer's crosslinks, turning it back into a thermoplastic. This allows for reprocessing to be achieved in a more sustainable manner such as at lower temperatures and shorter times. After the desired shape has been obtained, facile re‐crosslinking turns the material into a vitrimer, with full restoration of thermal stability, mechanical properties, and gel fraction. To achieve this, a carbene C─H insertion strategy is utilized to introduce an imine‐based crosslinker into various thermoplastics and plastic mixtures to convert them into vitrimers. Properties typical of vitrimers such as a retained polymer network at high temperatures, and an Arrhenius‐type relationship between stress relaxation rate and temperature are observed, while its mechanical properties such as elongation at break and tensile toughness, particularly for plastic mixtures are significantly enhanced, first by crosslinking, then further enhanced up to 8 folds by the reversible crosslinking process.

Non-animal derived recombinant collagen-based biomaterials as a promising strategy towards adipose tissue engineering

Adipose tissue engineering (ATE) has been gaining increasing interest over the past decades, offering promise for new and innovative breast reconstructive strategies. Animal-derived gelatin-methacryloyl (Gel-MA) has already been applied in a plethora of TE strategies. However, due to clinical concerns, related to the potential occurrence of immunoglobulin E-mediated immune responses and pathogen transmission, a shift towards defined, reproducible recombinant proteins has occurred. In the present study, a recombinant protein based on human collagen type I, enriched with arginine-glycine-aspartic acid was functionalized with photo-crosslinkable methacryloyl moieties (RCPhC1-MA), processed into 3D scaffolds and compared with frequently applied Gel-MA from animal origin using an indirect printing method applying poly-lactic acid as sacrificial mould. For both materials, similar gel fractions (>65%) and biodegradation times were obtained. In addition, a significantly lower mass swelling ratio (17.6 ± 1.5 versus 24.3 ± 1.4) and mechanical strength (Young's modulus: 1.1 ± 0.2 kPa versus 1.9 ± 0.3 kPa) were observed for RCPhC1-MA compared to Gel-MA scaffolds.In vitroseeding assays showed similar cell viabilities (>80%) and a higher initial cell attachment for the RCPhC1-MA scaffolds. Moreover, the seeded adipose-derived stem cells could be differentiated into the adipogenic lineage for both Gel-MA and RCPhC1-MA scaffolds, showing a trend towards superior differentiation for the RCPhC1-MA scaffolds based on the triglyceride and Bodipy assay. RCPhC1-MA scaffolds could result in a transition towards the exploitation of non-animal-derived biomaterials for ATE, omitting any regulatory concerns related to the use of animal derived products.

Effect of Prehydrolysis VTMS on the Structure–Property of Silane‐Terminated Polyurethane

ABSTRACTSilane‐terminated Polyurethane (SPU) is in high demand in the sealant and adhesive industries because of its exceptional cohesive strength and excellent adhesive properties. To close a self‐curable SPU resin was synthesized using a two‐step solution polymerization process for 12 h at pH 2.8 using the sol–gel method. Subsequently, the polyurethane prepolymer's NCO moiety was terminated by VTMS silanol to prepare SPU resin. FTIR and liquid state NMR were used to study VTMS hydrolysis in an acidic medium. Explored the effects of VTMS on SPU properties, including crystallinity, Mn and Mw, viscosity, gel fraction, thermal, surface, and mechanical. FTIR and NMR (1H and 13C) spectra confirmed the successful termination of the prepolymer's unreacted diisocyanate with the hydroxyl moiety of silanol. XPS and FTIR were used to analyze the chemical structures of urethane, urea, siloxane, and the hydrogen bonds between SPU moiety. Increased wt% of silanol exhibits increased gel fraction (80%–91%) with a decreased degree of swelling (76%–45%) showing the formation of a cross‐linked structure. Including siloxane in polyurethane showed a synergetic effect, resulting in enhanced thermal stability through reduction of weight loss. The SPU exhibited a three‐stage degradation pattern, accompanied by decreased glass transition temperature and crystallinity. Siloxane enrichment increased SPU surface roughness (Rq‐218 and Ra‐69 nm) and hydrophobicity (94°–103°). Silane wt% increase causes significant changes in Young's (2.19–51 N/mm2) modulus, strain %, and adhesive strength (4.60–5.62 MPa). Silane‐terminated polyurethane can be used successfully as an adhesive and sealant.

Effect of Mercerization on the Properties of Cellulose Fiber and Cellulose Hydrogel Extracted from Pineapple Leaf Fiber

AbstractThis study investigated the effects of alkaline treatment on the pineapple leaf fiber (PALF) cellulose extraction and the properties of cellulose hydrogel. PALF was treated with different concentrations of sodium hydroxide (NaOH) (2 to 10 wt %) and at room temperature (RT) and 80 °C. Then, extracted cellulose was then dissolved in N,N’‐dimethyl acetamide (DMAc)/lithium chloride (LiCl) solvent system and formed into hydrogel by phase inversion method. The Fourier transform infrared spectra shows the peak disappearance at 1606 cm−1 proves that lignin was removed starting from 6 and 4 wt % NaOH at RT and 80 °C, respectively. Higher NaOH concentrations treatment increased thermal stability and the crystallinity (71 to 79 %) of the fibers. Higher NaOH concentration and treatment temperature enhanced cellulose extraction from PALF, leading to more physical crosslinking during hydrogel formation. High amount of cellulose extracted decreased the hydrogel's swelling equilibrium and increased the gel fraction. The highest transmittance (87.8 %) and the lowest intensity of absorbance (at 280 nm corresponding to lignin) were obtained by the hydrogel prepared with PALF treated with 8 wt % NaOH at 80 °C. Clearly, this research findings provide new insights into optimizing cellulose extraction using alkaline treatment specifically for cellulose hydrogel formation.

UV-curable aromatic polyurethanes from different sustainable resources: Protocatechuic and cinnamic acids

An innovative aromatic monomer, 3,4-dihydroxybenzyl cinnamate (CDHB), was synthesized from protocatechuic and cinnamic acids. These latter can be obtained from different sustainable resources, such as plastic waste or biomass, by biotechnology and/or chemistry routes. From CDHB, used as chain extender, and aromatic or aliphatic diisocyanates, various aromatic thermoplastic polyurethanes (TPU) with cinnamic pendant chains were carefully synthesized and characterized. Different techniques such as NMR, FTIR, TGA and DSC have been used. The main results show that the TPUs exhibited good phase segregation and thermal stability, due to the aromaticity of the chain extender. The pendant cinnamic chains acted as internal plasticizer with a reduction of the glass transition temperature (Tg). The cinnamic groups were also able to undergo a [2 + 2] cycloaddition under UV irradiation, leading to the crosslinking of PU with a strong evolution of the properties. This reaction was followed by UV–Vis spectroscopy. 80 % of cycloaddition was reached in 20 h, significantly increasing PU gel fraction, Tg, and thermal stability. This study highlights the potential to create modulable sustainable and aromatic PU macromolecular architectures that can be UV curable and display enhanced properties.

Impact of a Bio-Cross-Linking Agent Obtained from Spent Coffee Grounds on the Physicochemical and Thermal Properties of Gelatin/Κ-Carrageenan Hydrogels.

Gelatine hydrogels can be prepared using different cross-linking methods, such as enzymatic, physical or chemical. Unfortunately, in the case of chemical cross-linking, the typically utilized synthetic cross-linkers are harmful to human health and the environment. Therefore, in accordance with the principles of green chemistry and sustainable development, we have obtained compounds for the chemical cross-linking of hydrogel polymers from the processing of spent coffee grounds. In this study, gelatin/κ-carrageenan hydrogels are cross-linked using a bio-cross-linking agent from spent coffee grounds. Their physicochemical and thermal properties are compared with those of standard physical gels. The chemical cross-linking was confirmed based on FT-IR spectra, which demonstrated the formation of new covalent bonds between the oxidized polyphenols included in the extract from the spent coffee grounds and the amide groups present in the gelatine structure. Significant differences were also observed in morphology (SEM images) and other physico-chemical characteristics (gel fraction, swelling ability, hardness). The chemically cross-linked hydrogels in comparison to physically ones are characterized by a better developed porous network, a slightly higher gel fraction (64.03 ± 4.52% as compared to 68.15 ± 0.77%), and a lower swelling ratio (3820 ± 45% as compared to 1773 ± 35%), while TGA results show that they have better thermal stability. The research confirmed the possibility of using the developed natural cross-linking agent in the process of obtaining hydrogel materials based on bio-polymers.

Tailoring pH-sensitive carboxymethyl tamarind kernel gum-based hydrogel for an efficient delivery of hydrophobic drug indomethacin

Polyacrylamide hydrogels have gained attention in the drug delivery field for their pH-dependent nature. Nevertheless, their limited degradability and lower entrapment efficiency for hydrophobic drugs hinder their utility in controlled drug release. This research aims to design a degradable pH-sensitive hydrogel for delivering the hydrophobic drug indomethacin to the colon. This work developed and optimized the hydrogels based on β-cyclodextrin, carboxymethyl tamarind kernel gum, and polyacrylamide with varying amounts of polyethylene glycol diacrylate. The optimized hydrogel exhibits 76.52 % gel fraction, 89.21 % porosity, 1000.27 % swelling, and 90.0 % equilibrium water content. The hydrogel was characterized using Attenuated Total Reflection-Fourier Transform Infrared spectroscopy, confirming the successful crosslinking of the synthesized hydrogel. Powder X-ray Diffraction revealed their amorphous nature while Scanning Electron Microscopy showed a porous surface morphology of the hydrogel. Moreover, rheology confirmed the hydrogel's elastic nature. Notably, the hydrogel demonstrated a drug release of 60.26 % at pH 7.4. Kinetic modelling of indomethacin release data indicated a Fickian diffusion release mechanism. Cytotoxicity tests on HCT-116 cells showed 79 % viability, and the hydrogel fully degraded within 10 days. These results confirmed the potential of synthesized β-CD/PAM/CMTKG hydrogel for controlled indomethacin delivery to the colon.

Poly(acrylic acid)-Sodium Alginate Superabsorbent Hydrogels Synthesized by Electron-Beam Irradiation-Part II: Swelling Kinetics and Absorption Behavior in Various Swelling Media.

Hybrid hydrogels with superabsorbent properties based on acrylic acid (20%), sodium alginate (0.5%) and poly(ethylene oxide) (0.1%) were obtained by electron-beam irradiation between 5 and 20 kGy, and are characterized by different physical and chemical methods; the first results reported showed gel fractions over 87%, cross-link densities under 9.9 × 103 mol/cm3 and swelling degrees of 400 g/g. Two types of hydrogels (without and with 0.1% initiator potassium persulfate) have been subjected to swelling and deswelling experiments in different swelling media with different pHs, chosen in accordance with the purpose for which these superabsorbent materials were obtained, i.e., water and nutrients carriers for agricultural purposes: 6.05 (distilled water), 7.66 (tap water), 5.40 (synthetic nutrient solution) and 7.45 (organic nutrient solution). Swelling kinetics and swelling dynamics have been also studied in order to investigate the influence of swelling media type and pH on the absorption phenomenon. The swelling and deswelling behaviors were influenced by the hydrogel characteristics and pH of the swelling media. Both the polymeric chain relaxation (non-Fickian diffusion) and macromolecular relaxation (super case II) phenomenon were highlighted as a function of swelling media type.

Digital Light Processing (DLP) 3D Printing of Caprolactone Copolymers with Tailored Properties through Crystallinity.

Digital light processing (DLP) 3D printing has shown great advantages such as high resolution in the fabrication of 3D objects toward a range of applications. Despite the rapid development of photocurable materials for DLP printing, tailoring properties to meet the specific demands for various applications remains challenging. Herein, we introduce copolymers of caprolactone and allyl caprolactone offering built-in functionality for thiol-ene photochemistry, thereby omitting the need for postfunctionalization. A crystalline block copolymer and an amorphous statistical copolymer were synthesized with the same comonomer composition and molecular weight. Thio-ene photocuring with a tetrafunctional thiol cross-linker was studied at different thiol to double-bond ratios for the copolymers and their blends. All formulations undergo rapid photocuring within several seconds of irradiation with slightly higher gel fractions observed for the statistical copolymer over the block copolymer under the same conditions, suggesting a somewhat higher cross-link density. Thermal properties of the networks were dependent on the presence of the semicrystalline block copolymer, where higher melting enthalpies were reached at higher block copolymer content. Similarly, crystallinity was found to be the main contributor to the mechanical properties. For a comparable composition, the modulus of a block copolymer network was found to be 31 times higher than that of the statistical copolymer network (27.7 vs 0.89 MPa). Intermediate moduli could be obtained by blending the two copolymers. DLP-printed scaffolds from these copolymers retained their thermal properties, therefore offering an efficient approach to tailoring mechanical properties, through crystallinity. Moreover, the printed scaffold displayed shape memory properties as the first example of poly(carprolactone) (PCL) copolymers in DLP printing. These materials are readily synthesized, offer fast and high-resolution 3D printing, and are degradable and cell compatible. They offer a straightforward approach to tailoring properties of PCL-based biomaterials and devices.