Metal Ion Complexes Research Articles

Designing Metal Complexes for Redox Flow Batteries By High-Throughput Synthesis

Redox flow batteries (RFBs) are an attractive device for high-capacity energy storage systems. Due to the disadvantages of vanadium RFBs such as high cost and limited temperature operability [1], researchers have been developing new redox couples to replace vanadium. The use of relatively inexpensive transition metals (Fe, Cr, Co, etc.) in combination with ligands to form metal-ligand complexes has received considerable attention [2]. The redox potential of a metal ion of a metal-ligand complex can be tuned by forming a complex with a ligand, and the metal-ligand complex form helps alleviate the crossover problem [3].A major challenge in the discovery and development of functional materials is to find and select the most optimized candidates from millions of possible materials [4]. High-throughput Synthesis (HTSy) enables simultaneous screening, synthesis and characterization of a large number of different material classes, providing unprecedented throughput and reproducibility. Therefore, HTSy can save energy, time, and cost for more efficient discovery of advanced functional materials [5]. In this study, based on HTSy methods, we used an automatic synthesis device (OT-2 liquid pipetting robot) to mix and heat metals (Ni, Cr, Cu, etc.) and ligand liquids to automatically design metal complexes. At the same time, a robot platform is developed to perform high-throughput electrochemical tests to quickly select suitable metal complexes for RFBs, and then conduct further related RFBs performance tests.

Synthesis, Characterization and Spectral Studies of Some Metal Ions Complexes with New Schiff Base Ligand Derived From 6- Amino Penicillanic Acid And Biological Screening Study For The Pt(II) Complex.

The complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg (II) and Pt(II)were prepared from the complexation reaction between the new Schiff base ligand and Selected Metal Ions. Ligand was derived from the condensation reaction of Oxo(4-(pyridin-2-yl)phenyl) methyline, 4-amino antipyrine, and 6-amino pencillic acid ). The ligand and its complexes were characterized by C.H.N elemental analysis, Uv-Vis, FT-IR, and molar conductivity, Atomic absorption, magnetic moment measurements and mass spectra studies. The results of this studies show the coordination sites for the ligand with the metal ion were to be through oxygen, nitrogen atoms of 6-amino pencillic acid, and the nitrogen atom of 4-amino antipyrine. The complexes were found to have the general formula [(M)(L)2]Cl2 where M = Co(II), Ni(II), Cu(II), Zn(II), Hg(II), and Cd(II), except the [Pt(L)Cl]Cl. The electronic spectral and magnetic measurement data indicated that the complexes exhibited octahedral geometry, except the Pt(II) complex suggested a square planar geometry around the central metal ion. The ligand forms shape as natural tridentate manner. The biological activity results showed the inhibitory effect for platinum(II) the complex. In this study the cytotoxicity of Pt(II) complex on human colon cancer cell line LS 174 T CRC was investigated and African green monkey kidney cells normal cells were MTT assay. The metal complexes showed selective cytotoxicity against colorectal, this metal Complex excelled in halting proliferation of LS 174 T CRC cancer cells line with median inhibitory concentration (IC50) values of Pt(II) complex. The results indicate undoubtedly the possibility of using them as antitumor drugs in the field of pharmacy colon cancer.

Synthesis and Characterization of a Novel Azo-Dye Schiff Base and Its Metal Ion Complexes Based on 1,2,4-Triazole Derivatives

The study focused on producing and examining the properties of the 2-(((3-mercapto-5-(4-nitrophenyl)-4H-1,2,4-triazol-4-yl)imino)methyl)-4-(((4-mercaptophenyl) diazenyl)phenol) ligand (L) and its complexes with three transition metal ions, namely Ni(II), Co(II), and Cu(II). The ligand was formed through diazotization and coupling reactions between 4-aminobenzenethiol and a coupling Schiff base derived from 1,2,4-triazole. The characterization of the ligand and its metal ion complexes was carried out using analytical techniques such as FTIR, 1H- and 13C-NMR, UV-visible spectroscopy, and thermal analysis (TGA and DTG). Various physical methods were employed to synthesize and analyze the properties of the three mononuclear Co(II), Ni(II), and Cu(II) complexes with the azo-dye Schiff's base ligand. Based on the microanalysis and spectroscopic results, it was determined that the coordination between the azo Schiff base ligand and the central metal ion occurred through the NOS-donating atoms of the ligand. The analysis of the electronic spectra revealed that the synthesized Co(II) and Ni(II) complexes exhibited an octahedral geometry, while the Cu(II) complex had a distorted octahedral geometry. The implications of the finding regarding the octahedral and distorted-octahedral geometries include expanding the structural diversity in coordination chemistry, providing insights into ligand-metal interactions, and understanding the influence of geometry on properties.

Computational and crystallographic study of hydrogen bonds in the second coordination sphere of chelated amino acids with a free water molecule: Influence of complex charge and metal ion

Hydrogen bonds of glycine complexes were calculated using quantum chemistry calculations at M06L-GD3/def2-TZVPP level and by analyzing the crystal structures from the Cambridge Structural Database (CSD). One hydrogen bond where amino acid plays the role of the H-donor (NH/O), and two where it plays the role of the H-acceptor (O1/HO, O1 is a coordinated oxygen atom, and, O2/HO, O2 is a non-coordinated oxygen atom) were investigated. The calculations were done on octahedral nickel(II), square pyramidal copper(II), square planar copper(II), palladium(II), and platinum(II) glycine complexes with different charges adjusted using water(s) and/or chlorine ion(s) as the remaining ligands. For NH/O hydrogen bond, interaction energies of neutral complexes are the weakest, from −5.2 to −7.2 kcal/mol for neutral, stronger for singly positive, from −8.3 to −12.1 kcal/mol, and the strongest for doubly positive complex, −16.9 kcal/mol. For O1/HO and O2/HO interactions, neutral complexes have weaker interaction energies (from −2.2 to −5.1 kcal/mol for O1/HO, and from −3.7 to −5.0 kcal/mol for O2/HO), than for singly negative complexes (from −6.9 to −8.2 kcal/mol for O1/HO, and from −8.0 to −9.0 kcal/mol for O2/HO). Additionally to the complex charge, metal oxidation number, coordination number, and metal atomic number also influence the hydrogen bond strength, however, the influence is smaller.

The use of Clitoria ternatea as sustainable detection tool for Ni (II) and Cu (II) ions in simple paper-based analytical device

Clitoria ternatea plants was growth widely in Indonesia. It was used as natural coloring in food or supplements. In this study, the C. ternatea flower was extracted using ethanol 70% and used for detection of metal ions (Ni, Cu) in aqueous medium. The ability of anthocyanins in C. ternatea extract to react with metal ions was studied using UV-Visible spectroscopy. It was found that the complex of metal ions with C. ternatea flower extract making the hypsocromic effect to the spectra of C. ternatea pure extract. Furthermore, simple paper based analytical device attached with C. ternatea extract was used as test spot to detect the metal ions. It reveals that the color of C. ternatea extract was changed and the calibration curve was obtained. The limit of detection (LOD) in the optimum pH for Ni (II) and Cu (II) was 8.89 ppm, and 4.49 ppm, respectively. Thus, this study showed that C. ternatea flower extract provides sustainable color detection for metal ions with economic and environmental benefits.

Exploring the Multifunctional PVC-DPG PolymerComplexes: Synthesis, Characterization and Evaluation of the Antibacterial Activity

Polyvinyl chloride (PVC) has attracted great attention because of its applications in different fields such as industrial and medical fields. In this work PVC has been reacted with diphenylglyoxime (DPG) in Tetrahydrofuran (THF) to form PVC–DPG polymer, then the synthesized polymer reacted with alcoholic solutions of different metal ions (Fe(II), Co(II), Ni(II), Pd(II), Pt(IV) and Cu(II) to form colored metal ion complexes. All compounds are characterized by Fourier-transform infrared (FTIR), Ultraviolet (UV-Vis) spectroscopies, magnetic susceptibility and conductivity measurements. All complexes were examined with staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative), confirming the biological activity against these bacteria

Equipping 1,4,7-Triazacyclononane with Substituents via Solid-Phase Synthesis.

Metal ion complexes frequently show substituted 1,4,7-triazacyclononane (tacn) as the ligand. Besides providing donor atoms for complex formation, tacn serves as a scaffold for equipping the complex with further functional units that are needed for the complementation and electronic tuning of the metal ion coordination sphere and/or add other features, e.g., light-absorbing antennas and groups for bioconjugation. To exploit the full potential of substituted tacn, strategies for directed syntheses of NO(R1,R1,R2) and NO(R1,R2,R3), i.e., tacn with two and even three different substituents R, are needed. Herein, we report a strategy that takes advantage of solid-phase synthesis in the assembly of the precursors NO(R1,R1,H) and NO(R1,R2,H). The assembly of NO(R1,R2,H) is based on a highly selective formation of NO(Cbz,tfAc,H), with Cbz being the link between tacn and solid phase. For this, tacn was loaded onto (4-nitrophenyl carbonate)-resin, thereby forming resin-bound (rb)-tacn, which corresponds to NO(Cbz,H,H) bound to the solid phase. Treatment of rb-tacn with ethyl trifluoroacetate gave rb-NO(tfAc,H), which corresponds to NO(Cbz,tfAc,H). With rb-tacn and rb-NO(tfAc,H) in hand, a variety of NO(R1,R1,H) and NO(R1,R2,H) were prepared, showing the broad applicability of the strategy with respect to the type of substituents and of reactions (nucleophilic substitution, reductive amination, aza-Michael addition, addition to epoxides, acylation). The study also identified limitations and points for improvement.

Effect of Europium Complexation on N,N,N′,N′-Tetraoctyldiglycolamide Degradation Against Gamma Radiation

AbstractDiglycolamide extractants (DGAs) are playing an important role for many of aqueous separation processes under development for the advanced nuclear fuel cycle. This family of ligands exhibits excellent extracting and resistant properties, with TODGA (N,N,N′,N′-tetraoctyldiglycolamide) being a particularly successful extractant studied intensively in recent decades. Nowadays, the main issues for TODGA-based solvents are related to the understanding and simulation of the radiolytic degradation under realistic conditions, which is limiting aspect for the development of an advanced aqueous nuclear separation process. In that sense, in this work, TODGA ligand stability, solvent composition and performance were evaluated considering the effect of metal complexation under gamma radiation. For that, the irradiation of a TODGA solvent in the presence of Eu metal was carried out, varying the ligand/metal ratio. The goal was to not only study TODGA degradation using HPLC–MS technique but also to identify and quantify its degradation compound under these experimental conditions. The results revealed a protection of TODGA molecules due to metal ion complexation, with no observed changes in the degradation pathway, as confirmed by the quantification of formed degradation compounds.

Anion Tuned Structural Modulation and Nonlinear Optical Effects of Metal-Ion Directed 310 -Helix Networks.

Metals play an important role in the structure and functions of various proteins. The combination of metal ions and peptides have been emerging as an attractive field to create advanced structures and biomaterials. Here, we are reporting the anion-influenced, silver ion coordinated diverse networks of designed short tripeptide 310 -helices with terminal pyridyl groups. The short peptides adopted classical right-handed, left-handed and 310 EL -helical conformations in the presence of different silver salts. The peptides have displayed conformational flexibility to accommodate different sizes and interactions of anions to yield a variety of metal-coordinated networks. The complexes of metal ions and peptides have shown different porous networks, right- and left-handed helical polymers, transformation of helix into superhelix and 2 : 2 metal-peptide macrocycles. Further, the metal-peptide crystals with inherent dipoles of helical peptides gave striking second harmonic generation response. The optical energy upconversion from NIR to red and green light is demonstrated. Overall, we have shown the utilization of short 310 -helices for the construction of diverse metal-coordinated helical networks and notable non-linear optical effects.

Catalytic oxidation of biorefractory cyanide-containing coking wastewater by deconjugation effect of bimetal copper-loaded activated carbon

Due to the strong complexation and conjugation of various metal ions, the biorefractory low-concentration total cyanides (TCNs) remain stable and tenacious in wastewater after physicochemical-biological treatment. This study proposes a copper-loaded activated carbon (AC/Cu) mechanism to effectively remove TCN in the complex system, where the bimetallic synergy of AC/Cu/Zn can enhance the cyanide removal capacity up to 24.78 mg-TCN/g-AC, which is superior to most as-reported technologies in thermodynamics and kinetics. This result can be attributed to the weakening conjugated effect of less-coordinated cuprous cyanide with a lower barrier of transition and ground state calculated by density functional theory (DFT). Then, the presence of coupled metal ions (such as Zn2+) exposes more free cyanide through complexation competition which is reflected in the further reduction of the transition state barrier. More importantly, the orbital hybridization is of general significance for the conjugate recombination and deconjugation of conjugated pollutants, which will provide a new direction for the removal of refractory pollutants.

Synthesis, Spectral Identification, Thermal and Antioxidant Studies for Ni (II), Pd (II), Pt (IV) and Au (III) Complexes With New Azo Ligand Derivatives from Tryptamine

In this study, a new Azo ligand 5-((2-(1H-indol-2-yl)ethyl)diazinyl)-2-aminophenol is synthesized from a reaction of Tryptamine with 2-aminophenol. The ligand and their metal ion complexes Ni(II), Pd(II) , Pt(IV) and Au(III) have been synthesized and characterized by various analytical techniques, including elemental microanalysis, metal content, chloride-containing, measurement of electrical conductivity, magnetic susceptibility, 1H and 13C-NMR, FT-IR, UV-Vis, mass spectra (MS), and thermal analysis (TGA and DSC) curves. The DCS curve was used to calculate the thermodynamic parameters ΔH, ΔS, and ΔG. The characterization results promote the metal complexes of azo ligand structures. The results indicate that the ligand behaves as a trident N, N, and O donor ligand for each and every produced complex, and the molar conductivity of all complexes indicates that none of the complexes were electrolytes. The antioxidant activity of the synthesized compounds was evaluated and determined against the DPPH radical (1.1-diphenyl-2-picrylhydrazyl) and compared to that of a standard natural antioxidant, gallic acid. The results show that the metal complexes are more effective at scavenging free radicals.

Antioxidant, Antimicrobial and Spectroscopic Discussion of Guanine Azo Ligand with Cu(II) and Ag (I) Complexes

In this paper, we have provided a very thorough analysis of a new novel chelate metal ion complex of [Cu(II),Ag(I)] prepared via the interaction with the ligand{ 2-amino-8-((4-chloro-3-hydroxyphenyl) diazenyl)azo]guanine} [LAAG], which is synthesized by diazo coupling of the 5-amino-2-chlorophenol with amino acid guanine. The ligand and its complexes are identified by a variety of techniques, like [HNMR, FTIR, and Uv-vis] spectral, thermal analysis (TGA), and element analyses (CHN). The molar ratio was achieved so that the Cu(II) complex has (1:2) (M:L) with octahedral geometry; however, the Ag(I) complex has (1:1) (M:L) with tetrahedral geometry, and the ligand acts as neutral N,N-bidentate; as well as the ligand (LAAG) and its complexes were assessed against the two types of bacteria (Klebsiella pneumonia, Staphylococcus aureus,antifungal (Candida), and antioxidant This study showed that all compounds (the ligand and its complexes) had antimicrobial activity and more biological activity.

Facile graphene quantum dot-anchoring strategy synthesis of single-atom iron-nitrogen electrocatalyst with enhanced ORR performance

Single-atom catalysts (SACs), especially atomically dispersed Fe–N[Formula: see text]–C based SACs, hold great promise to replace Pt-based electrocatalysts for oxygen-reduction reaction (ORR). Currently, synthesizing high-activity ORR electrocatalysts with atomically dispersed Fe–N[Formula: see text] site structures is still challenging due to their high surface free energy, which leads to easy migration and serious aggregation. Herein, we have designed a general graphene quantum dots (GQDs)-anchoring strategy to synthesize a single-iron-atom electrocatalyst (Fe–N-GQDs/PC) applied to ORR through calcining of N-GQDs-Fe[Formula: see text] modified porous carbon (PC) and melamine. Experiments demonstrate the N-GQDs consist of abundant oxygenated groups, which could lead to complexing metal ions and thus facilitating the formation of SACs. Furthermore, the Fe–N-GQDs/PC electrocatalyst exhibits outstanding electrocatalytic ORR activity in 0.1 M KOH media with half-wave potentials of 0.84 versus 0.85 V for Pt/C. This strategy has opened up new feasible ideas to produce SACs for electrochemical energy devices.

Novel azo metal chelates of 3-aminophthalhydrazide derivative: Structural investigation, evaluation of DNA cleavage, anticancer and molecular docking studies

Transition bivalent metal ion (Mn, Co, Ni, Cu, and Zn) complexes derived from an azo ligand (HLCU) having 1,3-diketone moiety with 3-aminophthalhydrazide were prepared and characterized by using elemental analyses, ultraviolet–visible, Fourier transform infrared, nuclear magnetic resonance (1H, 13C), electron spin resonance, molar conductivity and magnetic measurement studies. Molar conductivity value indicated the non-electrolytic nature of all complexes. The ligand coordinates with the metal ion as a tridentate pattern and the binding sites are carbonyl oxygen, hydrazo nitrogen and hydroxy oxygen of phthalhydrazide moiety. The fluorescence spectra of the compounds were recorded and the results revealed that ligand have higher emission intensity than metal complexes. The X-ray powder diffraction indicated that the ligand (HLCU) and nickel(II) complex have orthorhombic crystal lattices. The ligand and metal complexes were subjected to DNA cleavage activity on pUC18 plasmid DNA using the gel electrophoresis method. The cobalt(II) complex completely cleaved DNA and other compounds showing higher cleaving activity than the control. The antitumor activity of the compounds was screened using sulforhodamine B assay towards the breast cancer and leukaemia cancer cell lines. Manganese(II), cobalt(II) and nickel(II) complexes have more promising activity, and the IC50 value is < 10 μg/mL against the leukaemia carcinoma cell line, which is equally potent as the positive control (adriamycin). The molecular docking study was used to find the binding mode of ligand and complexes of cobalt(II) and nickel(II) towards the molecular target protein receptor. The binding affinity of these compounds is −9.8, −13.6 and −10.5 kcal/mol respectively. The cobalt(II) complex has a more effective binding nature than the ligand and nickel(II) complex. Drug-likeness character indicates moderate activity of HLCU, and [Co(HLCU)(H2O)3], [Ni(HLCU)H2O] complexes, in agreement with invitro results.

Biosynthetic amyloid fibril CsgA-Fe3O4 composites for sustainable removal of heavy metals from water

Removal of heavy metals from water has been a hot topic. However, few studies have been conducted for the tricky low concentration range. Experimental designs often have heavy metal concentrations much higher than the actual environmental loading, which leads to poor practical results of adsorbent materials. This study showed that amyloid fiber CsgA-Fe3O4 composites are ideal for the removal of heavy metals from water, especially at low concentrations. We constructed CsgA-Fe3O4 composites by fusing short functional peptides that specifically bind to Fe3O4 magnetic nanoparticles. The CsgA-Fe3O4 composites achieved 98.73 %, 98.43 %, and 93.00 % removal of 1 mg/L Cu2+, Cd2+, and Pb2+, respectively. Moreover, the adsorption rate remained above 80 % after six repeated adsorptions, indicating that CsgA-Fe3O4 was highly reusable. Meanwhile, the high removal rate (>90 %) of heavy metals in the simulated wastewater demonstrated the excellent environmental stability of CsgA-Fe3O4. Finally, by FT-IR and XPS characterization, we found that the adsorption mechanism of CsgA-Fe3O4 is mainly the complexation of surface oxygen-containing functional groups and heavy metal ions. In general, the CsgA-Fe3O4 composite is an efficient, inexpensive, and sustainable adsorption material for mitigating low concentrations of difficult-to-treat heavy metal pollution in water bodies.

Inhibition of Mycobacterium tuberculosis MtrA response regulator by anticancer drugs via computational methods

Mycobacterium tuberculosis (MTB) causes TB disease and millions of deaths are reported every year. Drug resistance TB and its complex treatment is a big problem worldwide. The present study aimed to design new and safer antitubercular compounds to tackle this serious threat. The unique drug target is the MtrAB Two-component regulatory system (2CRS) of mycobacteria. MtrAB system consists of MtrB sensor kinase (SK) and MtrA response regulator (RR). This system is essential in MTB and is involved in mycobacteria's proliferation. This important physiological process is operated by the phosphorylation of MtrB and then to MtrA. The phosphorylation mechanism triggers modulation in the expression of MtrA targets genes and helps perform appropriate function. This phenomenon depends on the active and inactive confirmation of MtrA, which involves a ligand (Metal ion complex e.g. Mg2+). In this study, anti-cancerous compounds were selected for the inhibition of MtrA. However, molecular docking exhibited binding affinity ranging from −10.8 to −4.7 kcal/mol, targeting the binding pocket of the selected Tuberculosis–MtrA protein (PDB ID: 5L8X). This energy difference between the native ligand and docked compounds showed that the six molecules: (Risperidone, 2-(benzofuran-2-yl)-6,7-dimethyl-4H-chromen-4-one, (2E)-1-(4-hydroxyphenyl)-3-(quinolin-4-yl)prop-2-en-1-one, Estradiol Cypionate, (2Z)-6-hydroxy-2-(3,4,5-trimethoxybenzylidene)-1-benzofuran-3(2H)-one, (2E)-3-(2,3-dihydro-1,4-benzodioxin-6-yl)-1-(3-hydroxyphenyl)prop-2-en-1-one) mentioned are more potent than the native ligand.These six molecules were first time reported as the inhibitor for MtrA of MtrAB Two-component regulatory system and can be utelize for further study.

Synthesis of ternary metal complexes of bivalent metal ions with benzimidazole derivative and their antimicrobial studies

Synthesis of ternary metal complexes of bivalent metal ions with benzimidazole derivative and their antimicrobial studies

Chelation and Metal-Ion Complex Formation of Chitosan Treated Cotton

&#x0D; &#x0D; &#x0D; Chitin dan chitosan adalah bahan “chelate” yang sangat kuat untuk ion transisi logam terutama tembaga, nikel dan merkuri, dan sifat-sifat ini yang akan intensif di bahas. Pada studi ini kain kapas (cotton) dikerjakan dengan larutan chitosan-asam polikarboksilat untuk memperoleh kain kapas-chitosan yang mengandung gugus group karboksilat (-COOH) dan gugus amina (-NH2) fungsional. Penggunaan asam polykarboksilat (asam sitrat dan maleik) pada pelarutan chitosan menghasilkan group karboksil 0,5 meqs/g pada kain yang dicelup dengan larutan chitosan asam karboksilat. Kemudian kain kapas yang telah mengandung gugus karboksilat dan gugus amina ini dicelupkan pada larutan garam logam (garam tembaga dan seng). Terbukti bahwa larutan garam tembaga (copper) memberikan warna biru pada kain, hal ini mengindikasikan telah terjadi reaksi kompleks atau “Chelate”. Implikasi dari hasil ini maka diperkirakan kandungan group karboksil dan amina ini akan mempengaruhi pada pencelupan kain, namun hal ini tidak diuji.&#x0D; Kata kunci : Chitosan, Kain Kapas, Chelate, Asam asetat, Asam citrate, Asam maleik, Tembaga sulphate, Tembaga acetate.&#x0D; Abstract&#x0D; Chitin and chitosan are powerfull chelating agents for transition metal ions, particularly copper, nickel and mercury, and these properties have been extensively reviewed. In this study, cotton fabric has been treated with chitosan- polycarboxylic acid solution to form chitosan treated cotton fabric containing carboxyl (-COOH) and amine (-NH2) functional groups. The use of polycarboxylic acids (citric and maleic acids) to dissolve chitosan has given carboxyl groups 0.5 meqs/g into chitosan treated cotton fabrics. Instead, the complexing of the treated cotton samples with copper and zinc salts was examined. The copper salt solutions gave blue fabrics confirming easily that complexing or chelation had occurred. There are implications for dyeing cotton making use of these groups but this was not investigated.&#x0D; Keyword : Chitosan, Cotton fabric, Chelation, Acetic acid, Citric acid, Maleic acid, Copper (II) sulphate, Copper (II) acetate.&#x0D; &#x0D; &#x0D;

Enhanced DPPH Radical Scavenging Activity and Enriched γ-Aminobutyric Acid in Mulberry Juice Fermented by the Probiotic Lactobacillus brevis S3

Mulberries, known for their high sugar content and rich bioactive compounds, have attracted attention for their potential health benefits. γ-Aminobutyric acid (GABA) is an amino acid with multiple physiological functions. To increase the GABA content and enhance the antioxidant capacity in fermented mulberry beverages, we screened a high-yielding strain, Lactobacillus brevis S3, known for its probiotic properties. L. brevis S3 demonstrated an excellent tolerance to simulated gastric acid, gastric juice, intestinal fluid, bile salts, osmotic pressure, and phenol, making it a safe and valuable probiotic candidate for mulberry fermentation. We attempted the addition of different nutritional components to enhance the GABA content in mulberry juice, including 1% yeast extract; 0.5% peptone; 0.01% metal ion complex (magnesium sulfate, manganese sulfate, and ferrous sulfate); combinations of yeast extract and peptone, and all three components. Mulberry juice supplemented with all three components reached a viable cell count of 1.2 × 1010 CFU/mL after 72 h. The antioxidant capacity and GABA titer were enhanced. The DPPH free radical scavenging capacity increased by 1.62 times, and the GABA content reached 7.48 g/L. By utilizing L. brevis S3 with excellent probiotic properties and supplementation with nutritional components, it is possible to produce low-sugar mulberry functional beverages with a high DPPH free radical scavenging capacity that are rich in GABA.

Alginate Conjugation Increases Toughness in Auricular Chondrocyte Seeded Collagen Hydrogels.

Current auricular cartilage replacements for pediatric microtia fail to address the need for long-term integration and neocartilage formation. While collagen hydrogels have been successful in fostering neocartilage formation, the toughness and extensibility of these materials do not match that of native tissue. This study used the N-terminal functionalization of collagen with alginate oligomers to improve toughness and extensibility through metal-ion complexation. Alginate conjugation was confirmed via FTIR spectroscopy. The retention of native collagen fibrillar structure, thermal gelation, and helical conformation in functionalized gels was confirmed via scanning electron microscopy, oscillatory shear rheology, and circular dichroism spectroscopy, respectively. Alginate-calcium complexation enabled a more than two-fold increase in modulus and work density in functionalized collagen with the addition of 50 mM CaCl2, whereas unmodified collagen decreased in both modulus and work density with increasing calcium concentration. Additionally, the extensibility of alginate-functionalized collagen was increased at 25 and 50 mM CaCl2. Following 2-week culture with auricular chondrocytes, alginate-functionalization had no effect on the cytocompatibility of collagen gels, with no effects on cell density, and increased glycosaminoglycan deposition. Custom MATLAB video analysis was then used to quantify fracture toughness, which was more than 5-fold higher following culture in functionalized collagen and almost three-fold higher in unmodified collagen.