Novel tyrosinase-based bisphenol-A biosensor for the determination of bisphenol-A in bracket adhesive in orthodontics

A novel biosensor for the determination of Bisphenol-A has been developed in this study. For this purpose, a carbon paste electrode modified with poly(amidoamine)-salicylidenimine platinum(II) (PAMAM-Sal-Pt(II)) and the tyrosinase enzyme was prepared. BPA determination was based on the electrochemical reduction of an enzymatically produced quinone compound at –0.15 V. Optimum working conditions for the prepared biosensor were investigated. The linear working range and detection limit were found to be 0.01–1.0 μM and 1 nM, respectively. The optimum pH value and working temperature were defined as 7.0 and 40 ℃, respectively. The reproducibility of the biosensor is very good. It was found that phenol, nitrophenol, urea, potassium nitrate, hexane, acetonitrile, and ethyl acetate do not interfere with the BPA determination. The prepared biosensor was used for the first time in dentistry for the determination of BPA in a resin-based composite material used as a bracket adhesive in orthodontics.

Qualitative enzymatic detection of organophosphate and carbamate insecticides

In this study, new polymers containing amides (TrisPS-Ntaa, and TrisPS-Ntaa-Fc) were synthesized by condensation reaction for qualitative identification of insecticides. The synthesized polymers, including amides were investigated by infrared spectroscopy (IR), scanning electron microscopy-energy dispersion X- ray spectrometry (SEM-EDX), and gel permeation chromatography (GPC). Then, acetylcholinesterase enzyme (AChE) was covalently immobilized on these polymers to improve properties (including activity, reusability, and storage stability). Accordingly, organophosphate (malathion, acephate, chlorpyrifos methyl) and carbamate (carbofuran, methiocarb, methomyl), which are used to prevent harmful organisms in some agricultural products were enzymatically determined based on their inhibitory activity on AChE.

Novel polymeric microspheres: Synthesis, enzyme immobilization, antimutagenic activity, and antimicrobial evaluation against pathogenic microorganisms

New polymeric microspheres containing azomethine (1a-1c and 2a-2c) were synthesized by condensation to compare the enzymatic properties of the enzyme glucose oxidase (GOx) and to investigate antimutagenic and antimicrobial activities. The polymeric microspheres were characterized by elemental analysis, infrared spectra (FT-IR), proton nuclear magnetic resonance spectra, thermal gravimetric analysis, and scanning electron microscopy analysis. The catalytic activity of the glucose oxidase enzyme follows Michaelis-Menten kinetics. Influence of temperature, reusability, and storage capacity of the free and immobilized glucose oxidase enzyme were investigated. It is determined that immobilized enzymes exhibit good storage stability and reusability. After immobilization of GOx in polymeric supports, the thermal stability of the enzyme increased and the maximum reaction rate (V_max ) decreased. The activity of the immobilized enzymes was preserved even after 5 months. The antibacterial and antifungal activity of the polymeric microspheres were evaluated by well-diffusion method against some selected pathogenic microorganisms. The antimutagenic properties of all compounds were also examined against sodium azide in human lymphocyte cells by micronuclei and sister chromatid exchange tests.

New multifunctional agents and their inhibitory effects on the acetyl cholinesterase enzyme

A novel series of 2-((-1-substituted phenyl-1H-tetrazol-5-yl)thio)-2,3-dihydro-1H-inden-1-one compounds were designed, synthesized, and evaluated as multi-potent anti-Alzheimer drug candidates. First, treatment of various organic isothiocyanates with sodium azide in the presence of pyridine gave corresponding 1-substituted phenyl-1H-tetrazol-5-thiol compounds. Then, novel 2-((-1-substituted phenyl-1H-tetrazol-5-yl)thio)-2,3-dihydro-1H-inden-1-one compounds were synthesized by treatment of 2,3-dihydro-1H-inden-1-one with the 1-substituted phenyl-1H-tetrazol-5-thiol in the presence of I2. The synthesized compounds were characterized by spectroscopic methods. The inhibitory effects of the synthesized compounds on the acetyl cholinesterase enzyme (AChE) were then tested. An o-iodo substituent displayed higher activity compared to the other analogs. The o-iodo substituent showed a mixed-type of the AChE with an IC50 value of 1.75 μM. For the studied compunds all IC50 values for AChE were in the  micromolar range.

Efficient determination and pesticide control by means of immobilization of acetylcholinesterase

Supports involving tetrazole (o/m/p-F-Tet-1H) were prepared to detect pesticides. This novel te-trazole including fluorine in different positions was attached to nanoparticles (2AEPS-(o/m/p-F-Tet-1H)) by a condensation method. Primarily, the tetrazole derivatives were characterized by 1H-NMR,13C-NMR and LC-MS. Then, nanoparticles were prepared by a condensation method in non-aqueous medium and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, gel permeation chromatography. The enzymatic properties of immobilized acetylcholinesterase (AChE) were investigated for the determination of phosmet. This research is the first example.

Nanospheres caped Pt(II) and Pt (IV): synthesis and evaluation as antimicrobial and Antifungal Agent

Antimicrobial and antifungal polymers are gaining the attention of pharmaceutical makers and industrial design. Nanospheres-Polymers attached Platinum(II) / (IV) complexes have been synthesized to investigate antimicrobial activities. Firstly, nanospheres involving Schiff bases were synthesized from (aminomethyl) polystyrene and four substitute salicylaldehyde (2-hydroxy benzaldehyde, 5-fluoro-2-hydroxy benzaldehyde, 5-kloro-2-hydroxy benzaldehyde, 5-bromo-2-hydroxy benzaldehyde). Secondly, polymers attached Platinum(II) / (IV) complexes have been prepared by means of template method. The IR spectra show that the ligands act in a monovalent bidentate fashion all nanospheres involving Schiff bases. Square-planar and octahedral structures are proposed for Pt(II) and Pt(IV), respectively. All these substances have been examined for antibacterial activity against pathogenic strains, and antifungal activity. In particular, Pt(IV) complexes were more potent bactericides than all of the synthesized substances.

Immobilization of acetylcholinesterase on Pt(II) and Pt(IV) attached nanoparticles for the determination of pesticides

Pt(ii) and Pt(iv)-tagged nanoparticles have been synthesized according to the template method for the identification of pesticides. Their morphologies have been investigated using scanning electron microscopy and characterized by means of spectral measurements. Then, acetylcholinesterase (AChE) was immobilized onto the nanoparticles. The AChE immobilized Pt(ii) and Pt(iv)-tagged nanomaterials show high reusability and storage capacity. The catalytic activity of AChE followed Michaelis-Menten kinetics. Assays for enzyme activity measurements demonstrate that the nanospheres tagged with Pt(ii) have a much better performance than those with Pt(iv). Furthermore, whether or not there was any interaction between the immobilized enzyme and 1-naphthyl-N-methylcarbamate, which is a carbamate insecticide, was examined.

Spectroscopic analysis and the excellent reusability of sphere-capped ferrocene in the oxidation of glucose oxidase

Sphere-capped ferrocene nanospheres with Schiff base spacers have been prepared using a template, and used as carriers to immobilize glucose oxidase (GOx). GOx immobilized on spheres with one C-spacer (APS-Fc) exhibited high binding affinity to the substrate, which was attributed to appropriate position for the GOx conformation. When glucose oxidase was immobilized with spacers of different lengths, it was found that storage stability decreased with increasing the length of the spacer. It has been found that nanospheres, including capped ferrocene, exhibit good performance as the immobilized supporters of GOx. (APS-EtFc-GOx) retain more than 10% of the initial activity after forty-two successive cycles, which is a remarkable result.

Nanoplatforms attached Schiff bases by condensation method; Investigation of glucose oxidase enzyme as biocatalysts

We report a easy approach for the immobilization of glucose oxidase enzyme (GOx) on nanoparticles. Nanoparticles-modified polystyrene-ANH2 (PSA) with some salicylaldehyde derivatives were synthesized by means of condensation and investigated the enzymatic properties of GOx immobilized on there. Modified polystyrenes were characterized using IR spectra, gel permeation chromatography, and scanning electron microscopy. All the characteristics of the immobilized glucose oxidase (PSA-SalH)-GOx, (PSA-SalCH3)-GOx, and (PSA)-GOx enzyme showed except one of them. Immobilized GOx on to (PSA) showed two optimum pH, other immobilized polymers were one optimum.

Schiff bases attached L-glutamine and L-asparagine: first investigation on antimutagenic and antimicrobial analyses

This study was conducted to evaluate the antimutagenic and antimicrobial activities of Schiff bases attached L-glutamine and L-asparagine. Antibacterial activities of the compounds against S. aureus, Sh. dys. typ 7, L. monocytogenes 4b, E. coli, S. typhi H, S. epidermis, Br. abortus, M. luteus, B. cereus, P. putida, and antifungal activity against Candida albicans were studied. These compounds were investigated for antimutagenic properties against Aflatoxin Bı (AFBı) using micronuclei (MN) assay in human lymphocyte cell culture in vitro. The protective role of these compounds against AFBı-induced MN is probably related to its doses.

Ni(II)-tetrahedral complexes: characterization, antimicrobial properties, theoretical studies and a new family of charge-transfer transitions

A new amine containing selenium and their five imine, (SeSchX)(X: -H, F, Cl, Br, CH3), and Ni (II) complexes, [Ni(SeSchX)(H2O)2]Cl/[Ni(SeSchCl)(H2O)Cl], were synthesized. The compounds were characterized by means of elemental analyses, (13)C and (1)H NMR (for imine), FT-IR, UV-Visible spectroscopy, TGA/DTA and elemental analyses. [Ni(SeSchCl)(H2O)Cl] complex from Ni(II) complexes changes color from yellow to orange in the range pH 5-7. [Ni(SeSchCl)(H2O)Cl] complex has ligand-to-metal charge-transfer (LMCT) transitions in the basic medium. Excitation characteristics and energetic of [Ni(SeSchCl)(H2O)Cl] complex, examined via TD-DFT calculations, reveals transitions of LMCT and π→π(*) character that matches the experimental values. [Ni(SeSchCl)(H2O)Cl] complex showed the highest antibacterial activity when compared to other complexes reported in this work.

Polystyrene attached Pt(IV)-azomethine, synthesis and immmobilization of glucose oxidase enzyme

Modified polystyrene with Pt(IV)-azomethine (APS-Sch-Pt) was synthesized by means of condensation and demonstrated to be a promising enzyme support by studying the enzymatic properties of glucose oxidase enzyme (GOx) immobilized on it. The characteristics of the immobilized glucose oxidase (APS-Sch-Pt-GOx) enzyme showed two optimum pH values that were pH = 4.0 and pH = 7. The insertion of stable Pt(IV)-azomethine spacers between the polystyrene backbone and the immobilized GOx, (APS-Sch-Pt-GOx), increases the enzymes' activity and improves their affinity towards the substrate even at pH = 4. The influence of temperature, reusability and storage capacity on the free and immobilized glucose oxidase enzyme was investigated. The storage stability of the immobilized glucose oxidase was shown to be eleven months in dry conditions at +4 °C.

Some Novel Amino Acid-Schiff Bases and their Complexes Synthesis, Characterization, Solid State Conductivity Behaviors and Potentiometric Studies

Three new Schiff bases derived from the condensation reaction of thiophene-2-carbaldehyde and DL-alanine, DL-valine and DL-phenylalanine have been synthesized and their Co(II), Ni(II) and Cu(II) complexes have been prepared. The Schiff bases and the complexes have been characterized by their analytical and spectral data. The protonation constants of the Schiff bases and stability constants of the complexes have been determined potentiometrically in aqueous medium at 25 °C and 0.1 M KCl ionic strength. Solid state conductivities of the synthesized substances were using the four-probe technique on a compressed pellet at room temperature.