Search Results (171)

Background: Chitosan (CS) crosslinked with genipin (GNP) provides a mild, non-toxic route to generate nanogels (NGs) with enhanced integrity and colloidal stability. Objectives: To develop and characterise CS-GNP NG as a novel platform for targeted cellular delivery, optimising design through physicochemical characterisation and biocompatibility evaluation. Methods: NGs were synthesised under optimised conditions by adjusting the pH of the CS solution, followed by high-intensity ultrasound (HIUS) to achieve disaggregation. Physicochemical characterisation was carried out using UV-Vis spectroscopy, FTIR, dynamic light scattering (DLS), and scanning electron microscopy (SEM). Rheological studies and SAXS analysis assessed structural properties. Biocompatibility was evaluated via MTT assay, and internalisation was monitored by fluorescence microscopy on mammalian cell lines. Results: NG formation was highly pH-dependent, with optimal configuration at pH 4.5, yielding stable, uniformly sized particles (~200 nm, ζ-potential +29 mV). Kinetic modelling showed a sigmoidal formation pattern, suggesting nucleation, growth, and stabilisation. FTIR confirmed covalent bonding between CS and GNP via primary amide bonds and Schiff bases. Rheology indicated pseudoplastic behaviour, and SAXS revealed a compact network formation. Biocompatibility assays confirmed non-cytotoxicity below 100 µg/mL and efficient cellular uptake. Conclusions: This study presents a rapid, reproducible protocol for generating colloidally stable, biocompatible NGs suitable for drug delivery. Full article

Green leaf volatiles (GLV) have been shown in the past to significantly affect herbivore performance in plants by activating direct and indirect defense measures. At the same time, insect herbivores have developed multiple mechanisms to reduce the quantities of Z-3-hexenal, the first product of the pathway. Among the various measures is the abundance of a molecule named hexenal trapping molecule (HALT), which appears to bind large quantities of freshly produced Z-3-hexenal (Z3al). Functional groups like -NH₂ within HALT may be responsible for the binding of Z3al. To test for this potential interaction, we tested different amino acids in various binding assays for their capacity to bind Z3al. We found a significant reduction in Z3al production in the presence of these amino acids, presumably through Schiff base formation. In a feeding assay with beet armyworm (Spodoptera exigua), we found a significant impact of a Z3al- or E2al-spiked artificial diet on growth and development. Together, these data indicate that the presence of Z3al in a diet can harm insect herbivores, which may help to further explain the efforts insect herbivores undertake to suppress the biosynthesis of this compound. Full article

In this study, a solvent-free, slow-curing, inherently flame-retardant polyurea coating was successfully developed through an optimized formulation. The novel polyurea was synthesized using mixed Schiff base latent curing agents derived from terminal polyether amines with different-number average molecular weights (D2000 and D400), methyl isobutyl ketone, and polyethyl phosphate glycol ester (OP550). Subsequently, polyurea/meta-aramid (PUA/AF) composite fabrics were fabricated via a scraping coating technique. Thermogravimetric analysis revealed enhanced char formation and reduced decomposition temperatures due to the incorporation of OP550. Comprehensive flame retardant performance was demonstrated through vertical flame testing, limiting oxygen index, and micro-scale combustion calorimetry, with results showing significantly reduced heat release rates, lower total heat release, and increased residual char. Mechanical evaluations indicated marked improvements in tearing, tensile, single-yarn tensile, and bursting forces, attributed to strong fiber–polyurea interfacial interactions, as confirmed by detailed SEM morphological analyses. Moreover, the PUA/AF composites exhibited excellent static puncture resistance and effective self-healing capability. Collectively, these advancements highlight the potential of PUA/AF composite fabrics as promising candidates for advanced protective textiles, integrating superior flame retardancy, mechanical strength, puncture resistance, and self-repairing functionality. Full article

Implant-associated infections (IAIs) are major complications in dental and orthopedic implants, potentially compromising osseointegration and eventually causing implant loosening or removal. Thus, early prevention of bacterial adhesion and biofilm formation is critical for successful long-term osseointegration. Polyetheretherketone (PEEK) exhibits excellent physicochemical properties and an elastic modulus similar to bone tissue, making it a promising material for dental and orthopedic implants. However, its inherent lack of antibacterial properties limits its ability to prevent IAIs. Herein, an antibacterial coating with controlled drug release and excellent biocompatibility is designed by immobilizing minocycline (Mino)-doped carboxymethyl chitosan (CMCS) onto the PEEK surface via a polydopamine (PDA)-mediated Michael addition and Schiff base reaction. The coating is characterized by SEM, XPS, water contact angle measurements, and in vitro Mino release assays. Antibacterial activity is evaluated using the zone of inhibition (ZOI), turbidity, and colony counting assays, while biocompatibility is assessed through a SEM analysis of cell morphology and CCK-8 assay. The results show that the Mino-modified coating is successfully fabricated on the PEEK surface, achieving sustained Mino release for up to 14 days. Among the three Mino concentrations, the PEEK-0.5Mino group demonstrates the best balance of antibacterial activity and biocompatibility, highlighting its potential for preventing IAIs in orthopedic and dental applications. Full article

Background/Objectives: A sustainable inflammatory response is a significant obstacle for diabetic wound care. In this study, the pH-sensitive multifunctional hydrogel ODex/BSA-Zn was fabricated via a Schiff base and coordination force for the first time. Methods: The hydrogel consisted of oxidized dextran (ODex), bovine serum albumin (BSA), and zinc ions (Zn²⁺) in the absence of an additional crosslinking agent. Results: The hydrogel showed excellent mechanical stability, fast self-healing ability, and significant anti-inflammatory effects, as demonstrated by the formation of dynamic covalent bonds between the aldehyde group (-CHO) of ODex and the amino group (-NH₂) of BSA via the Schiff base reaction, as well as the metal-ion coordination reaction of Zn²⁺ with the imidazole ring of BSA. In a diabetic mouse full-thickness cutaneous defect wound model, the ODex/BSA-Zn hydrogel could effectively inhibit the inflammatory response and increase collagen deposition, thereby accelerating the transition of macrophage M1 to M2 and promoting wound closure. This study offers a promising therapeutic approach for managing long-term diabetic ulcers. Full article

Four silane-containing Schiff base oligomers (o-SBNs and o-SBBs) were synthesized by high-temperature polycondensation reactions using silicon-based dialdehydes with naphthalene and 1,1’-binaphthalene diamine derivates. The samples showed a moderate solubility in common organic solvents, where the incorporation of TPS cores into o-SBN2 allows the formation of highly soluble material in non-polar solvents with higher molecular weights (11.58 kDa) and polydispersity. All oligo-SBs displayed high thermal resistance (above 450 °C), showing enhanced thermal stability for TPS-containing oligomers, with the degradation temperature exceeding 530 °C (o-SBB2) and high T_g values due to the higher aromatic content granted by TPS and 1,1’-binaphthalene moieties. Optical results of the oligo-SBs showed broad absorption and emission behavior in the visible spectrum, ranging from deep blue (o-SBN1 and o-SBB1) to blue (o-SBN2 and o-SBB2). The structure promotes a clear bathochromic shift for TPS-based oligomers, attributed to an extended π-conjugation across the backbone. In addition, the π-π overlap effect highlights larger Stokes shifts for the DMS core oligomers o-SN2 (133 nm) and o-SBB1 (195 nm). The oligo-SBs were found to be wide-bandgap materials, with E_g^opt values in the range of 2.60 eV to 3.67 eV. The higher molecular weight of o-SBN2, which provided an extended π-conjugation, allows the lowest value of E_g^opt (2.60 eV) to be achieved. In addition, DFT, TDDFT and EDDM calculations were performed on trimeric oligo-SBs, revealing that HOMOs are localized in the amine-terminal fraction, while LUMOs are localized over the terminal aldehyde groups. These findings highlight the used DMS and TPS cores in Schiff base materials, providing valuable insights into fine-tuning physicochemical properties through the use of suitable building blocks and their potential as optoelectronic materials. Full article

The separation of high-viscosity oil–water emulsions remains a global challenge due to ultra-stable interfaces and severe membrane fouling. In this paper, SiO₂ micro–nanoparticles coated with polyethyleneimine (PEI) were initially loaded onto a stainless steel substrate. This dual-functional design simultaneously modifies surface roughness and wettability. Furthermore, a covalent crosslinking network was created through the Schiff base reaction between PEI and glutaraldehyde (GA) to enhance the stability of the membrane. The membrane exhibits extreme wettability, superhydrophilicity (WCA = 0°), and underwater superoleophobicity (UWOCA = 156.9°), enabling a gravity-driven separation of pump oil emulsions with 99.9% efficiency and a flux of 1006 L·m⁻²·h⁻¹. Moreover, molecular dynamics (MD) simulations demonstrate that the SiO₂-PEI-GA-modified membrane promotes the formation of a stable hydration layer, reduces the oil–layer interaction energy by 85.54%, and exhibits superior underwater oleophobicity compared to the unmodified SSM. Efficiency is maintained at 99.8% after 10 cycles. This study provides a scalable strategy that combines covalent crosslinking with hydrophilic particle modification, effectively addressing the trade-off between separation performance and membrane longevity in the treatment of viscous emulsions. Full article

Chitosan (CS), a versatile biopolymer obtained through the deacetylation of chitin, has gained significant interest in biomedical and pharmaceutical applications due to its biocompatibility, biodegradability, and unique gel-forming capabilities. This review comprehensively analyzes CS-based gel development, covering its extraction from various natural sources, gelation mechanisms, and biomedical applications. Different extraction methods, including chemical, biological, and green techniques, are discussed regarding efficiency and sustainability. The review explores the physicochemical properties of CS that influence its gelation behavior, highlighting various gelation mechanisms such as physical, ionic, and chemical cross-linking. Recent advances in gel formation, including Schiff base reactions, Diels–Alder click chemistry, and thermosensitive gelation, have expanded the applicability of CS hydrogels. Furthermore, CS-based gels have demonstrated potential in wound healing, tissue engineering, drug delivery, and antimicrobial applications, offering controlled drug release, enhanced biocompatibility, and tunable mechanical properties. The incorporation of nanomaterials, bioactive molecules, and functional cross-linkers has further improved hydrogel performance. The current review underscores the growing significance of CS-based gels as innovative biomaterials in regenerative medicine and pharmaceutical sciences. Full article

Natural hydrogels have attracted considerable attention due to advantages of moisturizing, biocompatibility, and plasticity. In this study, a dual-network oxidized peach gum polysaccharide–carboxymethyl chitosan (OPGC) hydrogels with ultrafast self-healing ability was constructed by self-assembly using oxidized peach gum polysaccharide (OPGP) and carboxymethyl chitosan (CMCS). After complete fracture, OPGC hydrogels rapidly self-healed within 30 s due to the dual-network structure formed by the hydrogen bonds between the OPGP molecules and the Schiff base bonds between them and the CMCS. Meanwhile, the hydrogels exhibited good injectability and biocompatibility. With the increase of CMCS from 0.5 wt% to 2.5 wt%, the gel formation time of OPGC hydrogels was drastically shortened from 12 min to 3 min, while the strength and water-holding capacity were enhanced. Furthermore, experimental in vitro and in vivo animal studies demonstrated excellent drug loading capacity of OPGC hydrogels, and the release rate of bactericide could be controlled by adjusting the content of CMCS. The OPGC hydrogels have outstanding properties for potential applications in the health and medical fields. Full article

A pseudo-multicomponent one-pot protocol for the synthesis of 1,3-disubstituted imidazolidin-2-one is described, employing trans-(R,R)-diaminocyclohexane for the in situ formation of the Schiff base, followed by reduction to produce the respective diamine and cyclization with carbonyldiimidazole (CDI). This approach utilizes statistical analysis to optimize the reaction conditions, allowing a pseudo-multicomponent protocol to be proposed. The developed method demonstrates sustainability, efficiency, and potential applications in green chemistry, achieving yields ranging from 55% to 81%. This represents a significant advance in synthesizing heterocyclic compounds with biological and pharmacological applications. Full article

This study utilized the Schiff base reaction as a chemical bonding method to successfully graft 2-aminopyridine onto oxidized sodium alginate, resulting in the formation of modified sodium alginate (OSM). Subsequently, the OSM/polyacrylic acid (OSM/PAA) hydrogel was synthesized via a thermally initiated free radical polymerization process and evaluated as an adsorbent for the removal of heavy metal ions from wastewater. Comprehensive characterization of the prepared samples was performed using FT-IR, SEM, and TGA. The influence of temperature, pH, adsorbent dosage, contact time, and heavy metal ion concentration on the adsorption capacity of the OSM/PAA adsorbent in simulated wastewater was thoroughly investigated. Additionally, a detailed analysis of the adsorption thermodynamics, kinetics, and mechanisms was conducted. Experimental results indicated that at 25 °C, pH 5.0, and an adsorbent dosage of 0.4 g/L, the maximum adsorption capacities of the OSM/PAA hydrogel for Cu(II), Zn(II), and Ni(II) were 367.64 mg/g, 398.4 mg/g, and 409.83 mg/g, respectively. These findings suggest that the adsorption of heavy metal ions by OSM/PAA is a spontaneous, heterogeneous chemical process with significant potential for practical applications in wastewater treatment. Full article

The aim of this study was to prepare nanogels based on gelatin and xanthan-aldehyde for the enhancement of ibuprofen transdermal delivery. Firstly, the process of formulating nanogels using the reaction of Schiff’s base was optimized using experimental designs. Secondly, the structural characterization of nanogels was performed using laser particle size, zetometry, FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-Ray Diffraction), SEM (scanning electron microscopy), and thermogravimetric analysis. Finally, the evaluation of pharmacological characteristics and formulation therapeutic efficacy were achieved using in vitro dissolution kinetics, ex vivo transdermal diffusion studies, and an evaluation of in vivo anti-inflammatory activity. The results of the experimental plan show that the formulations containing a ratio of 15:10 ibuprofen/polymer and a ratio of 1:2 gelatin/xanthan-aldehyde with a gelling time of 2 h exhibited the best results; the formulations showed a mean diameter of 179.9 ± 6.2 nm, a polydispersity index of 0.193, which confirms monodispersed particles, a zeta potential of 24.7 mV, denoting a high degree of particle stability, and an encapsulation rate of 93.78%. The FTIR spectroscopy analysis showed the formation of imine function in the nanogel, and scanning electron microscopy showed the globular and porous form of the formulation. The incorporation of ibuprofen into nanogels improved their in vitro dissolution kinetics and ex vivo transdermal diffusion. The incorporation of nanogels into a patch system for its in vivo anti-inflammatory activity has shown excellent efficiency with a percentage of edema inhibition at a dose of 25 mg and 50 mg of 38.77 ± 1.6% and 82.03 ± 9.03%, respectively, while the commercial reference gel presented inhibition values at a dose of 25 mg and 50 mg of 10.61 ± 1.71% and 37.03 ± 11.43%, respectively. Thus, the innovative pharmaceutical form of ibuprofen offers a promising model for enhancing drug bioavailability and therapeutic effects while reducing adverse effects. Full article

Using chitosan and polyvinyl alcohol (PVA) as substrates, active packaging composite (VPC) films based on vanillin-crosslinked PVA/chitosan with different concentrations of added vanillin were prepared and characterized. The results show that the VPC films exhibited higher tightness and hydrophobicity, lower water content and water vapor permeability, as well as better UV resistance. The potential interactions between the film groups were analyzed by SEM, FTIR, and XRD, and the results showed that the formation of Schiff base and hydrogen bond interactions affected the properties of the films. The VPC films also showed excellent antioxidant activity. Therefore, vanillin-crosslinked PVA/chitosan active films have broader application prospects as packaging materials for food preservation. Full article

The effects of furfural and 5-methyl-2-furfural produced by the Maillard reaction on PhIP formation were investigated in chemical models and roasted pork patties. In the chemical models, the results indicated that increasing levels of furfural (r = −0.7338, R² = 0.9557) and 5-methyl-2-furfural (r = −0.7959, R² = 0.9864) significantly reduced PhIP formation, displaying a strong linear correlation. The effects of furfural and 5-methyl-2-furfural on the precursors of phenylalanine (Phe) and phenylacetaldehyde showed a significant reduction in the Phe level, while the level of phenylacetaldehyde was not increased. In addition, neither furfural nor 5-methyl-2-furfural could significantly reduce creatinine or PhIP. Further mechanism studies showed that furfural (5-methyl-2-furfural) directly captured Phe to form the corresponding Schiff base compounds a (2-((furan-2-ylmethylene) amino)-3-phenylpropanoic acid) and b (2-(((5-methylfuran-2-yl)methylene)amino)-3-phenylpropanoic acid). This process reduced the production of phenylacetaldehyde, thereby inhibiting the PhIP formation pathway. More importantly, these two compounds were detected in roasted pork patties to which glucose was added. The above pathway was finally confirmed in roasted pork patties. These results revealed that furfural and 5-methyl-2-furfural, formed during the Maillard reaction, play a significant role in inhibiting the formation of PhIP by reacting with Phe. Full article

Glioblastoma, an aggressive cancer, is difficult to treat due to its location, late detection, drug resistance, and poor absorption of chemotherapeutics. Intratumoral drug administration offers a promising potential treatment alternative with localized delivery and minimal systemic toxicity. Vanadium(V) coordination complexes, incorporating Schiff base and catecholate ligands, have shown effects as antiproliferative agents with tunable efficacy and reactivity, stability, steric bulk, hydrophobicity, uptake, and toxicity optimized for the intratumoral administration vehicle. A new series of oxovanadium(V) Schiff base–catecholate complexes were synthesized and characterized using nuclear magnetic resonance (NMR), UV-Vis, and infrared spectroscopy and mass spectrometry. Stability under physiological conditions was assessed via UV-Vis spectroscopy, and the antiproliferative activity was evaluated in T98G glioblastoma and SVG p12 normal glial cells using viability assays. The newly synthesized [VO(3-tBuHSHED)(TIPCAT)] complex was more stable (t_1/2 ~4.5 h) and had strong antiproliferative activity (IC₅₀ ~1.5 µM), comparing favorably with the current lead compound, [VO(HSHED)(DTB)]. The structural modifications enhanced stability, hydrophobicity, and steric bulk through substitution with iso-propyl and tert-butyl groups. The improved properties were attributed to steric hindrance associated with the new Schiff base and catecholato ligands, as well as the formation of non-toxic byproducts upon degradation. The [VO(3-tBuHSHED)(TIPCAT)] complex emerges as a promising candidate for glioblastoma therapy by demonstrating enhanced stability and a greater selectivity, which highlights the role of strategic ligand design in developing localized therapies for the treatment of resistant cancers. In reporting the new class of compounds effective against T98G glioblastoma cells, we describe the generally desirable properties that potential drugs being developed for intratumoral administration should have. Full article