A voltammetric sensor was proposed for simultaneous determination of paracetamol and diclofenac based on poly (L-arginine)/Au-graphene nanocomposite film deposited on a glassy carbon electrode. Cyclic voltammetry showed that paracetamol and diclofenac provided well - defined oxidation peaks at +0.443 and +0.644 V, respectively. Experimental parameters, such as the concentration of L-arginine and number of potential cycles in electro-polymerization step,accumulation potential and time, and the pH of buffer solution were optimized. Under the optimized conditions, linear relationships between oxidation peak current and concentration in the range 0.5 - 50.0 pM for paracetamol, and 0.5 - 40.0 pM for diclofenac were obtained in linear sweep voltammetry regime. The limits of detection (LOD) for paracetamol and diclofenac were 0.04 and 0.08 pM, respectively. The fabricated electrode exhibited good reproducibility and stability.The proposed method was successfully applied to the assessment of low concentrations of paracetamol and diclofenac in spiked human blood serum samples withsatisfactory results.

A técnica sol-gel foi usada na fabricação de um eletrodo cerâmico de carbono (CCE) renovável com complexo níquel-catecol (Ni-CA). O complexo foi depositado na superfície de nanotubos de carbono de parede múltipla-CCE por potencial cíclico na faixa de 0,0-0,8 V (vs. eletrodo saturado de calomelano, SCE). Ni-CA mostrou ter atividade catalítica sobre a reação redox de gabapentina. Observou-se uma relação linear da corrente de pico anódico com a concentração de gabapentina na faixa de 1,25-63,23 µmol L-1 com um limite de detecção de 0,5 µmol L-1. A resposta do eletrodo com respeito à gabapentina era bem reprodutível e observou-se estabilidade a longo prazo do eletrodo (acima de 2 meses). O eletrodo foi aplicado com sucesso à determinação de gabapentina em preparações farmacêuticas.

Sol-gel technique was used for the fabrication of a renewable carbon ceramic electrode (CCE) modified with nickel-catechol complex (Ni-CA). The complex was deposited on the surface of a multiwalled carbon nanotubes-CCE by potential cycling in the range of 0.0-0.8 V (vs. saturated calomel electrode, SCE). Ni-CA showed electrocatalytic activity towards the redox reaction of gabapentin. A linear relationship of anodic peak current with gabapentin concentration was observed in a range of 1.25-63.23 µmol L-1 with a limit of detection of 0.5 µmol L-1. The electrode response towards gabapentin was quite reproducible and a long-term stability of the electrode (more than 2 months) was observed. The electrode was successfully applied to the determination of gabapentin in pharmaceutical preparations.

A interação entre a droga anti-depressiva, sertralina, com o DNA de fita dupla (dsDNA) de timo de vitelo em tampão fisiológico (pH 7,4) foi determinada por espectrofotometria de UV-Vis, espectrofluorimetria, dicroísmo circular, espectroscopia no infravermelho com transformada de Fourier (FTIR), medições da viscosidade e estudos de fusão de DNA. Os espectros de absorção da droga com o DNA mostraram um efeito hipercrômico. Ao usar o reagente Hoechst como uma sonda de fluorescência ocorreu a extinção do pico de emissão na mistura DNA-Hoechst após a adição da sertralina. Os espectros de FTIR revelaram o modo de ligação de menor sulco entre o fármaco e o dsDNA. A constante de ligação da sertralina ao DNA foi calculada utilizando os dados espectroscópicos. Os parâmetros termodinâmicos calculados sugeriram que as interações eletrostáticas são forças importantes na formação do complexo DNA-sertralina.

The interaction of the antidepressant drug, sertraline, with calf thymus double stranded DNA (dsDNA) in physiological buffer (pH 7.4) was investigated by UV-Vis spectrophotometry, spectrofluorimetry, circular dichroism, Fourier transform infrared spectroscopy (FTIR), viscosity measurements and DNA melting studies. The absorption spectra of the drug with DNA showed a hyperchromic effect. Using Hoechst reagent as a fluorescence probe, quenching of the emission peak occurred in the DNA-Hoechst mixture when sertraline was added. The FTIR spectra revealed minor groove binding mode between the drug and the dsDNA. The binding constant of sertraline to DNA was calculated using spectroscopic data. The calculated thermodynamic parameters suggested that electrostatic interactions are important forces in the formation of sertraline-DNA complex.