A facile electrochemical sensor based on a composite of electrochemically reduced graphene oxide and a PEDOT:PSS modified glassy carbon electrode for uric acid detection.

A glassy carbon electrode modified with electrochemically reduced graphene oxide (ErGO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was developed for uric acid determination with dopamine as interference in artificial saliva. The electrochemical performance of the fabricated electrode was studied using both techniques of cyclic voltammetry (CV) and differential pulse voltammetry (DPV), under optimized conditions. Using DPV, the sensor based on ErGO/PEDOT:PSS modified GCE displayed a linear relationship in the concentration ranges of 10-100 µM for uric acid. This uric acid sensor exhibited a high sensitivity with detection limits of 1.08 µM and quantitation limit of 3.61 µM. This sensor also showed good reproducibility for uric acid detection in artificial saliva in 5 consecutive days of measurements. This device was successfully used to analyze uric acid in artificial saliva as well as in a human saliva sample using the standard addition method.

Remineralization and antibacterial/antibiofilm effects of toothpaste containing nanohydroxyapatite and Curcuma aeruginosa extract.

The aim of this study was to evaluate the effect of nanohydroxyapatite (nanoHAP) and Curcuma aeruginosa (C. aeruginosa) toothpastes on tooth remineralization and antibacterial/antibiofilm activity. Remineralization was evaluated by the morphological changes in extracted human premolar teeth following toothpaste application. The antibacterial and antibiofilm activities were evaluated by agar diffusion and microdilution methods, respectively, against S. mutans. Statistical approach was utilized to formulate 20 toothpastes with different concentration of nanoHAP and C. aeruginosa. We observed that the interaction among toothpaste ingredients determined the remineralization and antibacterial/antibiofilm activities. The optimum toothpaste formula (OF1) suggested by the prediction model was shown to induce remineralization and have comparable antibacterial activity to that of the control (chlorhexidine gluconate). Furthermore, the antibiofilm activity of this formula was higher to that of the control. The result obtained indicate that these novel toothpastes have potential in decreasing caries prevalence.

Development of neuraminidase detection using gold nanoparticles boron-doped diamond electrodes.

Gold nanoparticles-modified boron-doped diamond (AuNPs-BDD) electrodes, which were prepared with a self-assembly deposition of AuNPs at amine-terminated boron-doped diamond, were examined for voltammetric detection of neuraminidase (NA). The detection method was performed based on the difference of electrochemical responses of zanamivir at gold surface before and after the reaction with NA in phosphate buffer solution (PBS, pH 5.5). A linear calibration curve for zanamivir in 0.1 M PBS in the absence of NA was achieved in the concentration range of 1 × 10(-6) to 1 × 10(-5) M (R(2) = 0.99) with an estimated limit of detection (LOD) of 2.29 × 10(-6) M. Furthermore, using its reaction with 1.00 × 10(-5) M zanamivir, a linear calibration curve of NA can be obtained in the concentration range of 0-12 mU (R(2) = 0.99) with an estimated LOD of 0.12 mU. High reproducibility was shown with a relative standard deviation (RSD) of 1.14% (n = 30). These performances could be maintained when the detection was performed in mucin matrix. Comparison performed using gold-modified BDD (Au-BDD) electrodes suggested that the good performance of the detection method is due to the stability of the gold particles position at the BDD surface.