Immunochemical method for sulfasalazine determination in human plasma

Sulfasalazine is an antibiotic used in the treatment of inflammatory bowel diseases. For the assessment of sulfasalazine in several biological matrices, an Enzyme-Linked Immunosorbent Assay (ELISA) method based on polyclonal antibodies was developed and characterized.The immunoassay showed a high sensitivity (IC₅₀ = 0.51 ng mL⁻¹) and specificity, a detection limit of 0.02 ng mL⁻¹ and a dynamic range of 0.06-3.75 ng mL⁻¹ (80-20% inhibition). The immunoassay performed well when it was applied to spiked plasma samples (from 0.5 to 2.0 ng mL⁻¹) previously cleaned up by protein precipitation with methanol. Recoveries ranged from 83 to 119%, with a mean value of 99% (CV = 13%).Since sulfasalazine remaining of a treatment reaches the systemic circulation in unchanged form, the immunoassay can be applied to the determination of this pharmaceutical in human plasma in order to facilitate the control of the patients through the application of personal doses.     

Development of a Novel Molecularly Imprinted Overoxidized Polypyrrole Electrode for the Determination of Sulfasalazine

A novel molecularly imprinted overoxidized polypyrrole electrode was produced for the determination of sulfasalazine (SSZ). The electrode was attained by electropolymerization of pyrrole onto a pencil graphite electrode by cyclic voltammetry. The SSZ was penetrated into the structure during the process. Differential pulse voltammetry was used to determine performance of imprinted (MIP) and non‐imprinted (NIP) electrodes. The linear range was attained in the range between 1.0 to 10.0 ppm of SSZ (R²=0.9993) with a detection limit of 0.265 ppm. The developed MIP electrode and analysis method are suitable for analysis of SSZ with reproducible response and precision in real samples.     

Spectroscopic, thermal and antitumor investigations of sulfasalazine drug in situ complexation with alkaline earth metal ions

The complexes of sulfasalazine (H₃Suz) with some of alkaline metals Mg(II), Ca(II), Sr(II) and Ba(II) have been investigated. Sulfasalazine complexes were synthesized and characterized by spectroscopic tools; infrared spectra, electronic and mass spectra. The IR spectra of the prepared complexes were suggested that the H₃Suz behaves as a bi-dentate ligand through the carboxylic and phenolic groups. The molar conductance measurements gave an idea about the non-electrolytic behavior of the H₃Suz complexes. The thermal decomposition processes for metal(II) complexes of H₃Suz viz: [M(HSuz)(H₂O)₄] (where M = Mg(II), Ca(II), Sr(II) or Ba(II)) have been accomplished on the basis of TG/DTG and DTA studies, and the formula conforms to the stoichiometry of the complexes based on elemental analysis. The kinetic analyses of the thermal decomposition were studied using the Coats–Redfern and Horowitz–Metzger equations. The antitumor and antimicrobial activities of the H₃Suz and their alkaline metal(II) complexes were evaluated.     

高荧光量子产率钕、氮双掺杂碳点用于柳氮磺吡啶检测及Hela细胞成像

以柠檬酸氢二铵、缓血酸铵和硝酸钕为起始原料,通过水热法合成了荧光量子产率为93.05%、发蓝色荧光的钕、氮双掺杂碳点（Nd,N-CDs）。采用透射电子显微镜（TEM）、粉末X射线衍射（XRD）、红外光谱（FT-IR）及X射线光电子能谱（XPS）等技术对Nd,N-CDs的形貌及表面结构进行了详细表征,采用紫外可见吸收光谱及荧光光谱考察了其光学性质和稳定性。结果显示,药物分子柳氮磺吡啶（SSZ）能够使Nd,N-CDs的荧光显著降低,而金属离子及另外4种药物分子没有明显效果。由此,建立了一种选择性检测SSZ的荧光检测方法,线性检测范围在0.1~50 μmol/L之间,检出限低至0.05 μmol/L。机理探讨表明,荧光猝灭主要涉及动态猝灭和荧光共振能量转移两种机制。所建立的分析方法能用于测定实际药片中的SSZ含量,回收率为98.1%~104.2%。此外,Nd,N-CDs表现出很好的生物相容性,能够作为荧光探针穿透细胞壁使细胞质染色,因不会进一步穿透进入细胞核,很好的避免了对细胞的深层次破坏。     

柳氮磺胺吡啶的合成工艺改进

以磺胺吡啶和NaNO2为原料,在管式反应器中经重氮化反应合成磺胺吡啶重氮盐(2);2再与水杨酸偶合制备了柳氮磺胺吡啶,总收率87%,其结构经1H NMR,13C NMR和MS确证。     

Production of pyrite nanoparticles using high energy planetary ball milling for sonocatalytic degradation of sulfasalazine

Sonocatalytic performance of pyrite nanoparticles was evaluated by the degradation of sulfasalazine (SSZ). Pyrite nanoparticles were produced via a high energy mechanical ball milling (MBM) in different processing time from 2 h to 6 h, in the constant milling speed of 320 rpm. X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR) analysis and Brunauer–Emmett–Teller (BET) confirmed the production of pyrite nanoparticles during 6 h of ball milling with the average size distribution of 20–80 nm. The effects of various operational parameters including pH value, catalyst amount (mg/L), SSZ concentration (mg/L), ultrasonic frequency (kHz) and reaction time on the SSZ removal efficiency were examined. The obtained results showed that the maximum removal efficiency of 97.00% was obtained at pH value of 4, catalyst dosage of 0.5 g/L, SSZ concentration of 10 mg/L and reaction time of 30 min. Experimental results demonstrated that the kinetic of the degradation process can be demonstrated using Langmuir–Hinshelwood (L-H) kinetic model. The effect of different inorganic ions such as Cl⁻, CO₃²⁻ and SO₄²⁻ was investigated on the L-H reaction rate (k_r) and adsorption (K_s) constants. Results showed that the presence of the mentioned ions significantly influenced the L-H constants. The impact of ethanol as a OH radical scavenger and some enhancers including H₂O₂ and K₂S₂O₈ was investigated on the SSZ removal efficiency. Accordingly, the presence of ethanol suppressed SSZ degradation due to the quenching of OH radicals and the addition of K₂S₂O₈ and H₂O₂ increased the SSZ removal efficiency, due to the formation of SO₄⁻ and additional OH radicals, respectively. Under the identical conditions of operating parameters, pyrite nanoparticles maintained their catalytic activity during four consecutive runs.     

Structural and thermal characterization of cerium, thorium and uranyl complexes of sulfasalazine

Cerium(IV), Thorium(IV) and Uranyl(II) complexes with the ammonium salt of sulfasalazine drug (H2SSZ, HL-) have been studied. The structures of the complexes were elucidated using elemental analysis, IR and mass spectroscopy and thermal analysis. The complexes were isolated in 1:1 and 1:2 (M:L) ratios. The solid monocomplexes (1:1) (M:H(2)SSZ) were isolated in the general formulae [UO2(L)(H2O)2].2H2O and [M(L)(X)z(H2O)n].yH2O (M=Ce(IV) and Th(IV) (X=NO3, z=2, n=2, y=0-3)). The biscomplexes (1:2) (M:H2SSZ) solid chelates found to have the general formulae [UO2(HL)2].2H2O and [M(L)2(H2O)2] (M=Ce(IV) and Th(IV)). The thermal decomposition of the complexes should be discussed in relation to structure, and the thermodynamic parameters of the decomposition stages were evaluated applying Coats-Redfern and Horwitz-Mitzger methods.     

Electrochemical Oxidation of Sulfasalazine at a Glassy Carbon Electrode

Sulfasalazine (SSZ) is a pharmaceutical compound used for the treatment of rheumatoid arthritis. The electrochemical oxidation of SSZ at a glassy carbon electrode was studied by cyclic, differential pulse and square wave voltammetry in a wide pH range. For electrolytes with pH<11.0, the oxidation is an irreversible, diffusion‐control, pH‐dependent process that involves the transfer of one electron and one proton from the hydroxyl group of the salicylic moiety. For pH>11.0 the oxidation is pH‐independent, and a pK_a≈11 was determined. The formation of a quinone‐like oxidation product that undergoes two electrons and two protons reversible redox reaction was observed. Also, UV‐vis spectra of SSZ were recorded as a function of supporting electrolytes pH. An electrochemical oxidation mechanism was proposed.