Schiff Base Reaction Research Articles

Injectable Silver Nanoparticle-Based Hydrogel Dressings with Rapid Shape Adaptability and Antimicrobial Activity.

Burns and scalds often result in deep wounds that challenge adequate debridement and inflammation control using traditional sheet-like hydrogel dressings. Herein, we developed an antibacterial, injectable, and self-healing hydrogel (ADCM@Ag) by employing carboxymethyl chitosan (CMCS) for in situ green reduction of silver ions and utilizing a spontaneous Schiff base reaction with aldehyde-functionalized dextran (AD). SEM analysis revealed a porous structure within the hydrogel. Swelling and enzymatic degradation assays demonstrated that ADCM@Ag hydrogel possesses excellent fluid absorption capacity and biodegradability. Mechanical tests indicated good mechanical properties, allowing the hydrogel to withstand external forces when applied to animal wounds. The hydrogel exhibited good injectability, shape adaptability, and self-healing capability. Cell experiments showed that the ADCM@Ag hydrogel avoided the cytotoxicity caused by high concentrations of silver ions and had good cell compatibility. Antimicrobial assays showed that ADCM@Ag exhibited potent bactericidal effects against Gram-negative and Gram-positive bacteria, achieving at least 85% killing efficacy. Collectively, ADCM@Ag hydrogel has good potential for wound dressing applications.

Constructing covalent organic frameworks with dense thiophene S sites for effective iodine capture

Developing versatile sorption materials for radionuclide capture (e.g. iodine) is critical for nuclear energy and environmental science. Covalent organic frameworks (COFs) have recently become a new platform for developing sorption materials because of their high surface area and functionalised skeleton structure. Herein, two types of COF materials containing thiophene were designed as iodine sorbents and synthesised via a Schiff base reaction of benzo[1,2-b:3,4-b’:5,6-b’’]trithiophene-2,5,8-tricarbaldehyde, benzidine (DADP) and p-phenylenediamine (DAB): DADP-COF and DAB-COF. DAB-COF exhibits a unique granular-rod-like morphology and has a higher surface area (1775 m2/g) than DADP-COF (1140 m2/g), which is clearly beneficial for the physical adsorption of iodine. Meanwhile, the COF backbone is rich in N and S sites, which are advantageous for the chemical adsorption of iodine. These two features make the two prepared COFs ideal iodine sorption materials. DAB-COF demonstrates an excellent gaseous iodine adsorption capacity of 4.2 g/g, ranking it as one of the most effective iodine sorption materials, while DADP-COF exhibits a good adsorption capacity of over 235 mg/g for iodine in cyclohexane solutions. Density functional theory calculations prove that imine N and thiophene S serve as active sites during the iodine adsorption. DAB-COF exposes more active sites because of its higher surface area, leading to a higher iodine adsorption capacity than DADP-COF. The results of this study indicate that introducing thiophene to COFs improves sorption efficacy for sorption applications in general and particularly paves the way for developing stable and effective COF sorbents for iodine capture from various environments.

Constructing ESIPT-Capable α-Cyanostilbene Luminogens: Influence of Different Aromatic Substitutions Tethered to H-Acceptor (CH = N) on Photophysical Properties, Cu2+ and Fe3+ Detection.

Herein, two excited-state intramolecular proton transfer (ESIPT)-capable α-cyanostilbene luminogens were synthesized by Schiff base reaction of salicylaldehyde-like α-cyanostilbene candidate with 1-naphthylamine and 3-biphenylamine, respectively. We systematically analyzed their photophysical properties compared with their analogue, and demonstrated that their fluorescence behaviors could be elaborately modulated by different aromatic substitutions tethered to H-acceptor (CH = N). In virtue of the outstanding solid fluorescence, the 3-biphenylamine-decorated fluorophore was applied for monitoring Cu2+/Fe3+ qualitatively on the TLC-based test strip in real time and sensing Cu2+/Fe3+ quantitatively in the THF/H2O medium (fw = 90%, pH = 7.4). When the probe chelated with Cu2+/Fe3+, similar "turn-off" fluorescence signal outputs were triggered. From the fluorescence titration experiments, the detection limits were evaluated as 7.97 × 10- 8 M for Cu2+ and 8.24 × 10- 8 M for Fe3+, and the binding constant (Kα) values of the complexes were found to be 7.80 × 104 M-1 for Cu2+ and 9.06 × 104 M-1 for Fe3+. Job's plots indicated that probe complexed with Cu2+/Fe3+ in a 2:1 binding stoichiometry ratio. Furthermore, the probe was used to accurately quantify the Fe3+ spiked in real water specimens. This study offered a new perspective to construct ESIPT-capable α-cyanostilbene luminogen as the potential luminescent probe.

Eco-friendly and novel tannin-based wood adhesive enhanced with cellulose nanofibrils grafted by hyperbranched polyamides

Tannin-based adhesives, as a natural biobased adhesive, have the potential to expand their application in wood industry as substitutes for traditional adhesives. In this study, cellulose nanofibrils and hyperbranched polyamides (HBPA) were studied to address the challenges associated with the low crosslinking degree and poor water resistance characteristics of condensed tannin-based wood adhesives. The modification strategy focuses on grafting oxidized cellulose nanofibrils with hyperbranched polyamides through the Schiff base reaction. Comprehensive analyses, including FTIR, XPS, XRD, and TG, confirm the successful binding of oxidized cellulose nanofibrils with hyperbranched polyamides, demonstrating their potential to enhance the properties of tannin adhesives. Furthermore, the investigation about bonding strength, and water resistance of tannin adhesives reveal significant improvements in the mechanical and water resistance properties through this modification strategy. In particular, the maximum wet shear strength is 0.7 MPa, meeting the requirements for Class II plywood. This study provides valuable insights into improving the performance of tannin adhesives, offering promising implications for broader applications and contributing to eco-friendly practices in the wood industry.

Chitosan based fluorescent probe with AIE property for detection of Fe3+ and bacteria

Fluorescent probe with aggregation-induced emission (AIE) property has been widely used because of the advantages of high sensitivity, good selectivity and non-destructive testing. The development of fluorescent probe with good biocompatibility, photostability and biodegradability is of great significance in biomedicine and environmental detection. Herein, a novel type of fluorophore CS-TPE for detection of Fe3+ and bacteria was prepared by the Schiff base reaction of chitosan (CS) and 4-(1,2,2-triphenylethenyl) benzaldehyde (TPE-CHO). The fluorescence response mechanism of CS-TPE system was investigated by various characterization techniques. CS-TPE had an obvious AIE behavior with strong blue-green emissions at 473 nm and reaches the highest photoluminescence (PL) emission in 90 % H2O/ethanol mixtures. CS-TPE fluorescent probe exhibited sensitive quenching response to Fe3+, which can be used as a biosensor for detecting the concentration of Fe3+ with short response time (5 min), low detection limit (0.998 μM) and wide detection range (10–300 μM). Meanwhile, CS-TPE exhibited good antibacterial performance for S. aureus and E. coli. It is expected to realize the real-time fluorescence monitoring of metal ion detection and antibacterial process.

Preparation and characterization of polymeric cellulose wood adhesive with excellent bonding properties and water resistance

Developing the most abundant cellulose resources in nature as wood adhesives is a challenging but significant work. In this study, an oxidized cellulose-hexamethylene diamine-urea (OCHU) resin adhesive, of high bonding performance, and excellent water resistance has been prepared. The cellulose was firstly enzymatically hydrolyzed to increase its solubility and expose more hydroxyl groups, then oxidized by sodium periodate (NaIO4) to generate a biological compound being rich of aldehyde groups. The OCHU adhesive was prepared by crosslinking oxidized cellulose (OC) with a synthetic reactive polyurea (HU) polymer, which was formed through the deamidation reaction between hexamethylenediamine (H) and urea (U). This adhesive exhibited a 24 h cold water soaking strength of 1.61 MPa, 3 h hot water (63 °C) strength of 1.05 MPa and a dry strength of 1.71 MPa. Compared to oxidized cellulose-hexamethylenediamine (OCH) adhesive, a significant increase of 60 % in this adhesive's wet strength. The Schiff base and addition reactions in the preparation were confirmed by XPS, solid-state NMR, and FTIR. This cellulose-based wood adhesive has great market competitiveness for mass production and application in the plywood industry, due to its excellent bonding properties.

Multifunctional natamycin modified chondroitin sulfate eye drops with anti-inflammatory, antifungal and tissue repair functions possess therapeutic effects on fungal keratitis in mice.

Fungal keratitis (FK) is recognized as a stubborn ocular condition, caused by intense fungal invasiveness and heightened immune reaction. The glycosaminoglycan chondroitin sulfate exhibits properties of immunomodulation and tissue regeneration. In prior investigations, oxidized chondroitin sulfate (OCS) ameliorated the prognosis of FK in murine models. To further improve the curative efficacy, we used the antifungal drug natamycin to functionalize OCS and prepared oxidized chondroitin sulfate-natamycin (ON) eye drops. The structure of ON was characterized by FTIR, UV–vis, and XPS, revealing that the amino group of natamycin combined with the aldehyde group in OCS through Schiff base reaction. Antifungal experiments revealed that ON inhibited fungal growth and disrupted the mycelium structure. ON exhibited exceptional biocompatibility and promoted the proliferation of corneal epithelial cells. Pharmacokinetic analysis indicated that ON enhanced drug utilization by extending the mean residence time in tears. In murine FK, ON treatment reduced the clinical score and corneal fungal load, restored corneal stroma conformation, and facilitated epithelial repair. ON effectively inhibited neutrophil infiltration and decreased the expression of TLR-4, LOX-1, IL-1β, and TNF-α. Our research demonstrated that ON eye drops achieved multifunctional treatment for FK, including inhibiting fungal growth, promoting corneal repair, enhancing drug bioavailability, and controlling inflammatory reactions.

Spreadable thermosensitive nanocomposite hydrogel dressing with ultrasound-responsive bactericidal/repair-promoting regulation and cascade antioxidantion for infected burn wound repair

Treating severe burn wounds poses significant challenges, including considerable cell loss, excessive inflammation, and a high susceptibility to bacterial infections. Ideal burn dressings should exhibit excellent antibacterial properties, anti-inflammatory effects, and promote cell proliferation. Additionally, they need facilitate painless dressing changes and be user-friendly. Herein, we synthesized a thermosensitive hydrogel by crosslinking poly (N-isopropylacrylamide-co-allyloxybenzaldehyde) (PNA) and amino-terminated Pluronic F127 (APF) through a Schiff base reaction. It exhibited reversible gel-sol transition and spreadability. By incorporating piezoelectric gold nanoparticle-modified barium titanate (Au@BaTiO3) and cascade antioxidant MOF-818, a nanocomposite hydrogel dressing with diverse bioactive functionalities was developed. Results demonstrated that the nanocomposite hydrogel possessed gel-sol transition properties, maintained a stable gel state within a broad temperature range, and desirable self-healing property. Au@BaTiO3 exhibited good piezoelectric properties and ROS generation upon ultrasound stimulation, while MOF-818 displayed highly efficient cascade nanozyme activity. The combination of Au@BaTiO3 and MOF-818 promoted fibroblast proliferation and migration, reduced intracellular ROS levels, and induced anti-inflammatory polarization of macrophages under ultrasound stimulation. In vitro and in vivo antibacterial results disclosed that the nanocomposite hydrogel had excellent antibacterial activity under high-intensity ultrasound stimulation. When applied to infected burn wounds, the nanocomposite hydrogel can rapidly sterilize the wound upon initial high-intensity ultrasound, and then reduce inflammation and promote M2 macrophage polarization by the following low-intensity ultrasound stimulation, and thus accelerating the healing by improving granulation tissue formation, angiogenesis, and collagen deposition.

Selective cyanide ion detection using hydrazine carbothioamide probe: A fluorescence turn-on approach

This study reports the synthesis of various hydrazine carbothioamide derivatives through a Schiff base reaction, confirmed by FT-IR, NMR (1H and 13C), and HRMS spectroscopic methods. Among the synthesized derivatives, probe L ((4-fluorobenzylidene)-2-(1-phenylethylidene)hydrazine-1-carbothioamide) was identified as a highly selective fluorometric chemosensor based on its absorbance and emission spectra. Probe L showed a CN− ion-specific turn-on fluorescence response, with very little interference from other anions. Job's method established a 1:1 binding stoichiometry among probe L and the cyanide ion. The detection limits (LOD) and quantification (LOQ) were observed to be 0.639 µM and 2.116 µM, respectively. With the use of FT-IR spectroscopy, 1H NMR titration, 13C NMR and HRMS, the binding mechanism was clarified. Moreover, probe L was employed effectively for detecting CN− ions in water and food samples, highlighting its potential as a practical sensor for cyanide detection.

Mussel-Bioinspired Lignin Adhesive for Wearable Bioelectrodes.

As a natural "binder," lignin fixes cellulose in plants to foster growth and longevity. However, isolated lignin has a poor binding ability, which limits its biomedical applications. In this study, inspired by mussel adhesive proteins, acidic/basic amino acids (AAs) are introduced in alkali lignin (AL) to form ionic-π/spatial correlation interactions, followed by demethylation to create catechol residues for enhanced adhesion activity. Atomic force microscopy reveals that catechol residues are the primary adhesion structures, with basic AAs exhibiting superior synergistic effects compared to acidic AAs. Demethylated lysine-grafted AL exhibits the strongest adhesion force toward skin tissue. Molecular dynamic simulation and density functional theory calculations indicate that adhesion against skin tissue mainly results from hydrogen bonds and cation-π interactions, with the adhesion mechanism being based on the Gibbs free energy of the Schiff base reaction. In summary, a biomimetic electrode based on lignin inspired by mussel adhesive proteins is prepared; the presented method offers a straightforward strategy for the development of biomimetic adhesives. Furthermore, this mussel-inspired adhesive can be used as a wearable bioelectrode in biomedical applications.

Facile Synthesis of Functionalized TEOS–Acylpyrazolone Hybrid for Removal of Targeted Heavy Metal Ions: An Experimental and DFT Study

AbstractThis study broadens the application of 4‐acylpyrazolone, a leading β‐diketone chelating ligand, to include the removal of heavy metal ions in our current work. As organic–inorganic hybrids have gained considerable attention these days due to their widespread applications in the field of Chemistry, we have employed a Schiff base reaction to generate 4‐acetyl‐5‐methyl‐2‐phenyl‐2,4‐dihydro‐pyrazole‐3‐one incorporated polysiloxane material using a cost‐effective one‐pot synthesis. Optimization studies were performed to eliminate Pb(II), Cu(II), and Cr(VI) by varying the beginning metal ion content, the required amount of the adsorbent, pH, required time, and temperature. The considerable opportunity for monolayered chemisorption is illustrated by the observation that adsorption opts for the Langmuir adsorption isotherm, with R2 values of 0.99. It employs an endothermic adsorption mechanism in a study at multiple temperatures and follows a pseudo‐second‐order kinetic model. FMO and MESP investigations of complexes formed through adsorption were successfully carried out through DFT. Material reveals quick recycling up to three alternating rounds with removal efficiencies of 82%, 56%, and 47% for Pb(II), Cu(II), and Cr(VI), respectively. Therefore, it may further be used for extraction of heavy metals from industrial effluents and provides the basis for future scope of this type of organic–inorganic hybrids in water treatment.

Development and characterization of polyvinyl alcohol/chitosan crosslinked malic acid composite films with curcumin encapsulated in β-cyclodextrin for food packaging application

Considering that fruits are vulnerable to damage and waste during stockpiling, transport and marketing. Given this, an innovative curcumin inclusion compound (Cur@β-CD) was devised in this study to introduce oil-soluble curcumin (Cur) into water-soluble polyvinyl alcohol (PVA) materials, thereby fabricating food packaging films endowed with excellent properties. DPPH test manifested that the oxidation resistance for PCOMC-Cur@β-CD film was 95 % above PVA material. It was ascribed to the fact that the Cur@β-CD elevated the water solubility of Cur while the increase of water solubility heightened the antioxidant effect for Cur in the film. Additionally, the chitosan (CS) was crosslinked with malic acid (MA), which elevated the barrier property of the film, reduced the amount of oxygen transmission and further retarded the oxidation reaction of the fruits for packaging. The antibacterial test demonstrated that the antibacterial rates of PCOMC-Cur@β-CD film against E. coli and S. aureus reached 92 % and 95 %, respectively, which was attributed to the slow release of Cur when Cur@β-CD was dissolved in PVA material and the Schiff base reaction between Cur and amino groups on CS. These findings indicate that the PCOMC-Cur@β-CD film developed in this work can provide certain insights into the field of food packaging.

Enhancing long-segmental tracheal restoration: A self-repairing hydrogel loaded with chondrocytokines for sutureless anastomosis and cartilage regeneration

Artificial tracheal substitutes encounter significant challenges during long-segmental tracheal defects (LSTD) reconstruction, notably early postoperative anastomotic stenosis and tracheal chondromalacia. Mitigating early anastomotic stenosis by creating a compliant sutureless substitute is pivotal. Enhancing its chondrogenic capacity is equally critical for sustained healthy tracheal cartilage regeneration. This study proposes a self-healing hydrogel for sutureless tracheal anastomosis to mitigate anastomotic stenosis, enriched with kartogenin (KGN) and transforming growth factor-β1 (TGFβ1) to bolster chondrogenic properties. Initially, two precursor solutions were prepared: 1) aldehyde-modified hyaluronic acid with sulfonation and β-cyclodextrin-CHO loaded with KGN; 2) hydrazide-grafted gelatin loaded with TGFβ1. Coextrusion of these solutions resulted in a gelated G + TGFβ1/sH-CD + KGN hydrogel, characterized by a robust covalent bonding network of acylhydrazones between hydrazide and aldehyde groups, imparting excellent self-healing properties. The G + TGFβ1/sH-CD + KGN hydrogels, showcasing favorable cytocompatibility, excellent injectability, and rapid gelation, were loaded with bone marrow stem cells. These were customized into O-shaped rings and assembled into a malleable tracheal substitute using our established ring-to-tube method. This resultant compliant substitute facilitated sutureless anastomosis of LSTD in a rabbit model, attributed to the Schiff base reaction between the hydrogel's carbonyl group and the tissue's amino group. Notably, the tracheal substitute reduced early postoperative anastomotic stenosis, maintained tracheal patency, alleviated sputum blockage, promoted reepithelization, and increased the survival rate of the experimental rabbits. The sustained release of chondrocytokines resulted in excellent tracheal cartilage regeneration. Employing chondrocytokines-loaded hydrogels with self-healing properties represents a significant advancement in sutureless tracheal anastomosis and tracheal cartilage regeneration, holding promising potential in inhibiting early postoperative anastomotic stenosis and tracheal chondromalacia when treating LSTD.

Therapeutic effect of oxidized bletilla striata polysaccharide-natamycin eye drops on fungal keratitis.

Fungal keratitis (FK) usually develops to a poor clinical prognosis due to the fungal invasion and excessive inflammatory reaction. In order to enhance the therapeutic effect of natamycin (NAT), we used the anti-inflammatory biological polysaccharide bletilla striata polysaccharide (BSP) combined with NAT to prepare a new eye drop -- oxidized bletilla striata polysaccharide-natamycin (OBN). UV-vis, FT-IR, and fluorescence spectroscopy were used to identify the synthesis of OBN. Biocompatibility of OBN was determined by CCK-8, scratch assay, and corneal toxicity test. RAW264.7 cells and C57BL/6 mice were stimulated with A. fumigatus and treated with PBS, OBN, or NAT. The anti-inflammatory activity of OBN was detected by RT-PCR and ELISA. In mice with FK, the clinical scores were used to evaluate the effect of OBN; HE staining was performed to assess the corneal pathological changes; MPO assay and immunofluorescence staining were used to investigate neutrophil infiltration. OBN was synthesized by combining oxidized bletilla striata polysaccharide (OBSP) with NAT through Schiff base reaction. OBN did not affect cell viability at a concentration of 160μg/mL in HCECs, RAW264.7 cells, and mouse corneas. OBN versus NAT significantly improved the prognosis of A. fumigatus keratitis by reducing disease severity, neutrophil infiltration, and expression of inflammatory factors in vivo. Additionally, OBN treatment down-regulated the mRNA and protein expression levels of inflammatory factors IL-1β, TNF-α, and IL-6 in RAW264.7 and mouse models. OBN is a compound prepared by covalently linking OBSP to the imino group of NAT through Schiff base reaction. OBN treatment down-regulated inflammation and improved the prognosis of mice with A. fumigatus keratitis.

Antibacterial and antioxidative hydrogel dressings based on tannic acid-gelatin/oxidized sodium alginate loaded with zinc oxide nanoparticles for promoting wound healing

Wound infection resulting in delayed wound healing and wound deterioration remains a clinical challenge. Recently, multifunctional hydrogel dressing was a promising strategy which has attracted wide attention in preventing wound infection and promoting wound healing. In this study, a hybrid hydrogel made of gelatin (GL), tannic acid (TA), oxidized sodium alginate (OSA), and zinc oxide nanoparticles (ZnO NPs) was prepared mainly by double network cross-linking approach, named tannic acid-gelatin/oxidized sodium alginate/zinc oxide (TA-GL/OSA/ZnO). The composite hydrogels exhibited improved mechanical properties, which provided by TA modified the structure of GL network, Schiff base reaction between GL and OSA, and the strengthening effect of ZnO NPs. Meanwhile, the composite hydrogel showed high antibacterial activity against Staphylococcus aureus (S. aureus) (97.8 % ± 0.9 %) and Escherichia coli (E. coli) (96.6 % ± 1.2 %), attributed to the synergistic effect of TA and ZnO NPs. Furthermore, benefiting from the good antioxidative properties of TA, the sustain-released Zn2+ with the good capability to kill bacteria, and promoting the regeneration of skin epithelial tissues in BALB/c mice constantly, the multifunctional hydrogel had a significant therapeutic effect on wound healing and broad application prospects.

Dual COF functionalized magnetic MXene composite for enhancing magnetic solid phase extraction of thiophene compounds from oilfield produced waters prior to GC-MS/MS analysis

In this study, a novel COFTABT@COFTATp modified magnetic MXene composite (CoFe2O4 @Ti3C2 @COFTABT@COFTATp) was synthesized by Schiff base reaction and irre-versible enol-keto tautomerization, and employed to establish a sensitive monitoring method for six thiophene compounds in oilfield produced water samples based on magnetic solid-phase extraction (MSPE) prior to gas chromatography coupled with a triple quadruple mass spectrometer (GC-MS/MS). The designed magnetic materials exhibited unexpected enrichment ability to target thiophene compounds and achieved good extraction efficiencies ranging from 83 % to 98 %. The developed MSPE/GC-MS/MS method exhibited good linearity in the range of 0.001–100 μg L−1, and obtained lower limits of detection ranging from 0.39 to 1.9 ng L−1. The spiked recoveries of thiophene compounds obtained in three oilfield produced water samples were over the range of 96.26 %−99.54 % with relative standard deviations (RSDs) less than 3.7 %. Notably, benzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene were detected in three oilfield-produced water samples. Furthermore, the material still kept favorable stability after six recycling experiments. The adsorption kinetics, adsorption isotherms as well as adsorption thermodynamics of thiophene compounds were investigated in detail to provide insight into the mechanisms. Overall, the present work contributed a promising strategy for designing and synthesizing new functionalized materials for the enrichment and detection of typical pollutants in the environment.

Bioinspired ‘phenol-amine’ cross-linking and mineral reinforcement enable strong, tough, and formaldehyde-free tannic acid-based adhesives

Conventional tannin-based adhesives have limitations such as formaldehyde emission, inadequate strength and toughness, which restrict their practical applications. Herein, motivated by the natural mechanisms of ‘phenol-amine’ cross-linking and biomineralization, a strong, tough and formaldehyde-free tannic acid-based adhesive was prepared by using all-biomass feedstock. The adhesive was prepared by integrating tannic acid-Zn nanoparticles (TA-Zn NPs), hyperbranched polyamide-grafted dialdehyde chitosan (HPCS), and triglycidylamine (TGA), which formed the fundamental cross-linking network of the prepared adhesive through a Schiff base reaction. The dry and wet bonding strength of the adhesive achieved 1.91 MPa and 1.54 MPa, respectively. The presence of sacrificial bonds such as N…Zn complexation and hydrogen bonding in the adhesive significantly enhance its toughness with a debonding work of 0.595 J. Benefiting from the exceptional antimicrobial properties of TA, chitosan, and Zn2+, the prepared adhesive demonstrated excellent mechanical properties even after being stored in a humid environment for 2 days, with wet and dry bond strength of 1.42 MPa and 1.10 MPa, respectively. Moreover, this adhesive exhibited remarkable resistance to mildew for a duration of 30 days and emitted lower volatile organic compounds compared to other synthetic and biomass adhesives. This innovative bionic strategy holds great potential in enhancing the toughness and functionality of adhesives and composites.

In situ forming hydrogels based on modified gellan gum/chitosan for ocular drug delivery of timolol maleate

In situ forming hydrogels are suitable candidates for increasing drug residence time in ocular drug delivery. In this study, gellan gum (GG) was oxidized to form aldehyde groups and in situ gelling hydrogels were synthesized based on a Schiff-base reaction between oxidized GG (OGG) and chitosan (CS) in the presence of β-glycerophosphate. The effect of OGG and CS concentration on the physical and chemical properties of the resulting hydrogels was investigated. The FT-IR spectroscopy confirmed the chemical modification of OGG as well as the functional groups of the prepared hydrogels. The scanning electron microscope (SEM) revealed the highly porous structure of hydrogels. The obtained hydrogels indicated a high swelling degree and degradability. Also, the rheological studies demonstrated self-healing behavior, shear thinning, thixotropy, and mucoadhesion properties for the developed hydrogels. The results of in vitro and ex vivo studies showed that the timolol-loaded hydrogel with a higher amount of OGG has a higher release rate. Moreover, the MTT cytotoxicity test on bone marrow mesenchymal stem cells (BMSCs) confirmed that developed hydrogels are not toxic. The obtained results revealed that the developed hydrogels can be a desirable choice for the ocular drug delivery of timolol in the treatment of glaucoma.

β-Ketoenamine Porous Organic Polymers for High-Efficiency Carbon Dioxide Adsorption and Separation.

To mitigate the greenhouse effect, a number of porous organic polymers (POPs) has been developed for carbon capture. Considering the permanent quadrupole of symmetrical CO2 molecules, the integration of electron-rich groups into POPs is a feasible way to enhance the dipole-quadrupole interactions between host and guest. To comprehensively explore the effect of pore environment, including specific surface area, pore size, and number of heteroatoms, on carbon dioxide adsorption capacity, we synthesized a series of microporous POPs with different content of β-ketoenamine structures via Schiff-base condensation reactions. These materials exhibit high BET specific surface areas, high stability, and excellent CO2 adsorption capacity. It is worth mentioning that the CO2 adsorption capacity and CO2/N2 selectivity of TAPPy-TFP reaches 3.87 mmol g-1 and 27. This work demonstrates that the introduction of β-ketoenamine sites directly through condensation reaction is an effective strategy to improve the carbon dioxide adsorption performance of carbon dioxide.

Non-Enzymatic Detection of Glucose and Ketones in Urine using Paper-Based Analytical Devices

Diabetes, driven by unbalanced diets and unhealthy lifestyles, is highly prevalent. In Indonesia, its prevalence is projected to reach 28.6 million by 2045. Microfluidic paper-based analytical devices (μPADs) are paper-based analytical tools that use hydrophilic paper for measurement and hydrophobic barriers to control fluid flow. This research aims to develop a non-enzymatic method for detecting glucose and ketones in artificial urine using S2Z-μPADs. The fabrication of S2Z-μPADs involves printing the design on Whatman No. 1 paper using wax printing and applying silver nanoparticles for glucose detection and the Schiff base reaction for ketone detection. The results show that the optimum condition for glucose detection is achieved with an AgNO3 concentration of 500 mM. A NaOH concentration of 10 M. Acetoacetate detection is optimized with a glycine concentration of 1 M, sodium nitroprusside concentration of 15%, NaOH concentration of 1 M, a drying time of 8 minutes, and a reaction time of 10 minutes. Validation results demonstrate good linearity for glucose (R² = 0.9821) and ketones (R² = 0.995). High precision was achieved with relative standard deviation (RSD) values of 3.792% for glucose and 1.482% for ketones. The obtained limits of detection (LOD) and limits of quantification (LOQ) indicate that the developed S2Z-μPADs can differentiate between each category of diabetes. The accuracy of glucose and ketone detection ranges from 87.463% to 97.374%. The high accuracy of the μPADs highlights their potential for reliable diabetes management and effective disease monitoring.