Transition Metal (II) Complexes of (E)-N-(4-methylbenzylidene)-2-((Z)-(4-methylbenzylidene)amino)benzamides: Synthesis, Characterization and their Biological Evaluation

In this paper, cerium sulfate tetrahydrate (Ce(IV)) dissolved in acid-aqueous medium and mercaptosuccinic acid (MSA) redox couple was used to synthesize the crosslinked copolymer of acrylamide (AAm), lithium methacrylate (LiMA), and N,N’-methylene bisacrylamide (MBAAm) in the presence of ethylenediaminetetraacetic acid tetrasodium salt (EDTANa4). The effects of various mole amounts of AAm and LiMA at constant crosslinker concentration and mole amounts of total monomer/MBAAm at constant amounts of AAm and LiMA on the swelling behaviors and swelling kinetics of synthesized hydrogels were investigated in distilled water. The use of hydrogel, including lithium methacrylate ionic groups, for the removal of copper ions from aqueous solutions was examined by using the batch adsorption method. In the adsorption process of copper ions on hydrogels containing LiMA groups, the effects of parameters such as the amount of hydrogel, initial Cu(II) concentration, adsorption time, and pH of solution were investigated.

Synthesis and Swelling Behaviors of Hydrogels Containing LiMA Groups and its Use in Cu(II) Adsorption from Aqueous Solution

In this paper, cerium sulfate tetrahydrate (Ce(IV)) dissolved in acid-aqueous medium and mercaptosuccinic acid (MSA) redox couple was used to synthesize the crosslinked copolymer of acrylamide (AAm), lithium methacrylate (LiMA), and N,N’-methylene bisacrylamide (MBAAm) in the presence of ethylenediaminetetraacetic acid tetrasodium salt (EDTANa4). The effects of various mole amounts of AAm and LiMA at constant crosslinker concentration and mole amounts of total monomer/MBAAm at constant amounts of AAm and LiMA on the swelling behaviors and swelling kinetics of synthesized hydrogels were investigated in distilled water. The use of hydrogel, including lithium methacrylate ionic groups, for the removal of copper ions from aqueous solutions was examined by using the batch adsorption method. In the adsorption process of copper ions on hydrogels containing LiMA groups, the effects of parameters such as the amount of hydrogel, initial Cu(II) concentration, adsorption time, and pH of solution were investigated.

Reaction behaviour of peptide-based single thiol-thioesters exchange reaction substrate in the presence of externally added thiols

Identification of patterns in chemical reaction pathways aids in the effective design of molecules for specific applications. Here, we report on model reactions with a water-soluble single thiol-thioester exchange (TTE) reaction substrate, which was designed taking in view biological and medical applications. This substrate consists of the thio-depsipeptide, Ac-Pro-Leu-Gly-SLeu-Leu-Gly-NEtSH (TDP) and does not yield foul-smelling thiol exchange products when compared with aromatic thiol containing single TTE substrates. TDP generates an α,ω-dithiol crosslinker in situ in a ‘pseudo intramolecular’ TTE. Competitive intermolecular TTE of TDP with externally added “basic” thiols increased the crosslinker concentration whilst “acidic” thiols decreased its concentration. TDP could potentially enable in situ bioconjugation and crosslinking applications. Graphic abstract The competition between ‘pseudo intramolecular’ and intermolecular exchange of a peptide-based thiol-thioester exchange (TTE) substrate can be used to control the relative amount of final exchange products based on size and pKa values of externally added thiols. Potential application of this system can be seen in the development of TTE substrates for the rapid identification of thiols by dynamic combinatorial screening.

Tailoring Chitosan/LTA Zeolite Hybrid Aerogels for Anionic and Cationic Dye Adsorption

Chitosan (CS) is largely employed in environmental applications as an adsorbent of anionic dyes, due to the presence in its chemical structure of amine groups that, if protonated, act as adsorbing sites for negatively charged molecules. Efficient adsorption of both cationic and anionic dyes is thus not achievable with a pristine chitosan adsorbent, but it requires the combination of two or more components. Here, we show that simultaneous adsorption of cationic and anionic dyes can be obtained by embedding Linde Type A (LTA) zeolite particles in a crosslinked CS-based aerogel. In order to optimize dye removal ability of the hybrid aerogel, we target the crosslinker concentration so that crosslinking is mainly activated during the thermal treatment after the fast freezing of the CS/LTA mixture. The adsorption of isotherms is obtained for different CS/LTA weight ratios and for different types of anionic and cationic dyes. Irrespective of the formulation, the Langmuir model was found to accurately describe the adsorption isotherms. The optimal tradeoff in the adsorption behavior was obtained with the CS/LTA aerogel (1:1 weight ratio), for which the maximum uptake of indigo carmine (anionic dye) and rhodamine 6G (cationic dye) is 103 and 43 mg g−1, respectively. The behavior observed for the adsorption capacity and energy cannot be rationalized as a pure superposition of the two components, but suggests that reciprocal steric effects, chemical heterogeneity, and molecular interactions between CS and LTA zeolite particles play an important role.

Microencapsulation of Peppermint Oil by Complex Coacervation and Subsequent Spray Drying Using Bovine Serum Albumin/Gum Acacia and an Oxidized Starch Crosslinker

Most liquid food flavours such as essential oils are volatile and prone to degradation in the presence of oxygen, light, moisture and high temperatures. Microencapsulation of volatile ingredients prior to use in food or beverages is a commonly used process to limit loss and degradation of flavours and aromas during processing and storage. Here, peppermint essential oil was microencapsulated via complex coacervation using a combination of bovine serum albumin and gum Acacia as wall materials. The resulting core-shell microcapsules were chemically crosslinked with a modified food-grade starch, and subsequently spray dried, resulting in dry microcapsules which could be easily redispersed in aqueous solutions. Microcapsule formation and stability, as well as microencapsulation yield of peppermint oil, were investigated as a function of polymer concentration, core material load/wall thickness and crosslinker concentration. The crosslinked peppermint oil microcapsules were spherical and mononuclear both before and after spray drying and redispersion, whereas control coacervate samples without crosslinker did not withstand the spray drying process. Microencapsulation yield as analysed by GC-MS showed no loss of peppermint oil during or after complex coacervation, and 54% loss after spray drying for the best combination of Polymer:Oil ratio and crosslinker concentration used here, indicating good overall protection of the core material.

Tuning the Mechanical and Geometric Properties of Electrochemically Aligned Collagen Threads Towards Applications in Biohybrid Robotics

Electrochemically Aligned Collagen (ELAC) threads fabricated by the isoelectric focusing (IF) of collagen have previously shown potential in tissue engineering and more recently in the fabrication of biohybrid robot structures. For applications in biohybrid robotics, ELAC structures are needed that are both robust and compliant enough to facilitate muscle actuation. However, studies on the effects of IF parameters, and the interactions of such fabrication parameters, on the mechanical and geometric properties of resulting ELAC threads have not been previously found in literature. Understanding the impact of these manufacturing parameters on the material properties is critical to facilitate biohybrid robot design. In this study, the effects of IF duration, IF voltage, and collagen solution concentration were investigated and showed statistically significant effects on adjusting ELAC properties via single-factor experiments. The interactions between parameters exhibited significant joint effects on ELAC property tuning through two-factor experiments. Scanning electron microscopy and 2,4,6-trinitrobenzenesulfonic assays revealed the correlation between high mechanical properties and a combination of low porosity and high degree of crosslinking. By simply tuning IF parameters without changing other fabrication steps, such as crosslinker concentration, ELAC threads with a wide range of mechanical and geometric properties were fabricated. The average tensile modulus of the resulting ELAC threads ranged from 198±90 to 758±138 MPa. The average cross-sectional area ranged from 7756±1000 to 1775±457 µm2. The resultant mapping between IF parameters and ELAC thread properties enabled the production of strong and flexible threads with customizable properties.