Application of laser light scattering to the determination of molecular weight, second virial coefficient, and radius of gyration of chitosan

Enhancing the optical properties of [P(MMA-co-AN)/ZrO2]TF by doping fluorescein dye, TD-DFT/DMOl3 simulations and COVID-19 main protease docking

Poly methyl methacrylate-co-acrylonitrile [P(MMA-co-AN)]HB hybrid blend was first synthesized by precipitation polymerization and characterized by static light scattering. With a thickness of 200 ± 5 nm, the hybrid nanocomposite of [P(MMA-co-AN)/ZrO2]HNC thin films were fabricated by spin coating method. X-Ray diffraction studies showed a monoclinic cell structure with an average crystalline size of 180 nm for the fabricated films. An improvement in the optical properties were figured out when fluorescein dye was doped in the hybrid nanocomposite. Where the optical energy gap was decreased from 4.31 to 4.025 eV for fluorescein doped hybrid nanocomposite. While a possible energy transfer between ZrO2 and fluorescein was investigated in the laser photoluminescence spectra. DFT-CASTEP simulations were deployed to calculate the theoretical optical properties for the molecules under consideration. The structural and optical simulations of [P(MMA-co-AN)/ZrO2]HNC were found to match the experimental data. Molecular docking studies of [P(MMA-co-AN)/ZrO2]Iso against the main protease of novel corona virus COVID 19 (PDB code 6LU7 Hormone) showed an interesting interaction.

Synthesis, Characterization, and Anticancer Potency of Branched Poly (p-Hydroxy Styrene) Schiff-Bases

A significant issue in cancer biology is finding anticancer therapies that effectively kill cancer cells. Through the use of several aldehydes, Schiff bases based on branched poly (p-hydroxy styrene) are created. The branched polymer is first chloroacetylated, then aminated with 1,4-phenylenediamine, and finally, aldehydes are reacted with the aminated polymer to produce the Schiff base compounds. Through the utilization of FTIR, TGA, XRD, NMR, and elemental analysis, all synthesized Schiff-bases are identified and characterized. Further, the antineoplastic potential of all Schiff bases is evaluated against different cancer cell lines. The results gained from this study indicate that the Schiff base polymers have cytotoxic power against cancer cells depending on cancer cell type and this antiproliferation potency is dose-concentration dependent. Importantly, the prepared S1 Schiff-base polymer shows potent cytotoxicity and is able to trigger the apoptosis and reactive oxygen species (ROS) in MCF-7 cells. Further, it downregulates VEGFR protein expression. The Schiff base polymers would have extensive applications in the biological disciplines.

Microwave-assisted of new derivatives of polyimine conjugated polymer based on Schiff base: synthesis, characterization, and photo-physical properties as a photoluminescent materials

The condensation of pyrrole-2,5-dicarbaldehyde (1) with 5-(2-amino-4-phenylthiazol-5-yl)-4-phenylthiazol-2-amine (2) and/or 5-(4-Amino-phenyl)-4-phenylthiazol-2-amine (3) gave new poly(Z)-N-((5-(iminomethyl)-1H-pyrrol-2-yl)methylene)-5-(2-((E)-(5-(iminomethyl)-I-pyrrol-2-yl)methyleneamino)-4-phenylthiazol-5-yl)-4-phenylthiaol-2-amine (P1) and/or poly(E)-N-((5-(iminomethyl)-1H-pyrrol-2-yl)methylene)-5-(4-((E)-(5-(iminomethyl)-1H-pyrrol-2-yl)methyleneamino)phenyl)-4-phenylthiaol-2-amine (P2) as a novel conjugated polymer by microwave irradiation and traditional heating.. It is evident that the microwave irradiation technique quickly raised the molecular weight of polyimines. In addition to quantifying the molecular weight of the resultant polyimines. All the polyimines were characterized using FTIR, XRD, H1NMR, TGA, and DSC. The optical characteristics of polyimine derivatives were investigated using a UV-Vis spectrophotometer. The absorption spectra showed a main absorption band around 372 nm for polyimine (P1) and 381 nm for polyimine (P2). The optical energy was calculated and found to be 2.49 and 2.68 eV. The photoluminescence of the polyimine derivatives was measured and analyzed by spectrofluorometer and Laser photoluminescence experiment and the emission color was studied using CIE graphs. The fluorescence spectra showed an emission peak at 548 nm for polyimine (P1) with yellow green color in CIE graph, while for polyimine (P2) the emission band was located at 440.5 nm with blue color in CIE graph. Photoluminescence quantum yield PLQY was measured for the polyimine P1 and P2 in both liquid and Solid states and indicated the AIE behavior of the polyimines. TD-DFT simulations were applied to the polyimine derivatives where the structures were geometrically optimized and the spectroscopic characterizations were evaluated.

Synthesis, electrospinning, and molecular docking of poly(methyl methacrylate) Schiff bases and their applications as polymeric antimicrobial agents and for dye removal

The antibacterial activity of a variety of modified poly(methyl methacrylate) Schiff bases against common microbial infections and removal of methylene blue (MB) dye were screened. The Schiff bases were synthesized from the reaction of the modified (PMMA) with vanillin (PMMA)Van and cinnamaldehyde (PMMA)Cin. By using Fourier transformer infrared (FT-IR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), the structures of the nanofibers of the synthesized Schiff bases were confirmed. The modified Kirky-Bauer method was used to screen the antibacterial activities of all the obtained materials against various bacterial species, including gram-positive bacterial (Bacillus subtilis (4k1p), Staphylococcus aureus), Gram-negative bacteria (Escherichia coli (7ab3), Pseudomonas aeruginosa). Inhibition zones against gram-positive bacteria ranged in diameter from 7 to 14 mm, whereas for the Gram-negative bacteria, the inhibition zones found to be ranged between 6 and 13 mm. With a minimum bactericidal concentration (MBC) of 8 mg/mL and a minimum inhibitory concentration (MIC) of 2 mg/mL, (PMMA)Van shown the greatest antibacterial activity. Lastly, molecular docking research was done to better understand the interactions between this series' targets and inhibitors for (PMMA)Van and (PMMA)Cin (4k1p and 7ab3). Molecular modeling of these surface-adsorbed polymers indicated that (PMMA)Van binds more strongly with Nitrogen than does (PMMA)Cin through extra hydrogen-bonding interactions. All the developed materials were evaluated for the removal of 0.1 g/L methylene blue dye (MB) from an aqueous solution. The elimination percentage of MB dye ranged from 26.67% by using 0.05 g powder of (PMMA)Cin to 85.63% by employing 0.05 g nanofibers of (PMMA)Van.

Ferrocene-Based Terpolyamides and Their PDMS-Containing Block Copolymers: Synthesis and Physical Properties

Aromatic polyamides are well-known as high-performance materials due to their outstanding properties making them useful in a wide range of applications. However, their limited solubility in common organic solvents restricts their processability and becomes a hurdle in their applicability. This study is focused on the synthesis of processable ferrocene-based terpolyamides and their polydimethylsiloxane (PDMS)-containing block copolymers, using low-temperature solution polycondensation methodology. All the synthesized materials were structurally characterized using FTIR and ¹H NMR spectroscopic techniques. The ferrocene-based terpolymers and block copolymers were soluble in common organic solvents, while the organic analogs were found only soluble in sulfuric acid. WXRD analysis showed the amorphous nature of the materials, while the SEM analysis exposed the modified surface of the ferrocene-based block copolymers. The structure-property relationship of the materials was further elucidated by their water absorption and thermal behavior. These materials showed low to no water absorption along with their high limiting oxygen index (LOI) values depicting their good flame-retardant behavior. DFT studies also supported the role of various monomers in the polycondensation reaction where the electron pair donation from HOMO of diamine monomer to the LUMO of acyl chloride was predicted, along with the calculation of various other parameters of the representative terpolymers and block copolymers.

KOH/thiourea aqueous solution: A potential solvent for studying the dissolution mechanism and chain conformation of corn starch

Non-derivatizing, high-efficiency and low-toxicity solvents are important for studying the dissolution behavior and potential applications of starch. In this study, we investigated the starch dissolution mechanism and molecular conformation in KOH/thiourea aqueous solutions and compared these with KOH/urea and KOH aqueous solutions. Solubility analysis revealed that the KOH/thiourea solution demonstrates a better ability to dissolve corn starch than KOH/urea and KOH solutions. Rheological behavior and dynamic and static light scattering indicated that starch is stable in KOH/thiourea solution and exists as a regular star structure. Fourier transform infrared spectroscopy, ¹³C NMR, and molecular dynamics simulations indicated that hydrated K⁺ and OH^- destroy the strong starch hydrogen bond interactions; thiourea hydrate self-assembles into a shell surrounding the starch-KOH complex through interaction with KOH, whereas there is no direct strong interaction between urea and KOH. Therefore, adding thiourea to a KOH solution can promote dissolution and prevent self-aggregation of the starch chain.

Kinetics of Ferritin Self-Assembly by Laser Light Scattering: Impact of Subunit Concentration, pH, and Ionic Strength

Ferritins, the cellular iron repositories, are self-assembled, hollow spherical nanocage proteins composed of 24 subunits. The self-assembly process in ferritin generates the electrostatic gradient to rapidly sequester Fe(II) ions, thereby minimizing its toxicity (Fenton reaction). Although the factors that drive self-assembly and control its kinetics are little investigated, its inherent reversibility has been utilized for cellular imaging and targeted drug delivery. The current work tracks the kinetics of ferritin self-assembly by laser light scattering and investigates the factors that influence the process. The formation of partially structured subunit-monomers/dimers, at pH ≤ 1.5, serves as the starting material for the self-assembly, which upon increasing the pH exhibits biphasic behavior (a rapid assembly process coupled with subunit folding followed by a slower reassembly/reorganization process) and completes within 10 min. The ferritin self-assembly accelerated with subunit concentration and ionic strength (t_1/2 decreases in both the cases) but slowed down with the pH of the medium from 5.5 to 7.5 (t_1/2 increases). These findings would help to regulate the ferritin self-assembly to enhance the loading/unloading of drugs/nanomaterials for exploiting it as a nanocarrier and nanoreactor.