The aim of the present study was to characterize and preliminary assess the cytotoxicity and genotoxicity of different PMMA-TiO2 nanocomposites suitable to be used for two-parts stereolithographic complete denture manufacturing. In order to improve mechanical and antibacterial characteristics of the materials for 3D printing dentures, two matrix materials consisting in commercially available solutions of poly(methyl methacrylate) (PMMA), referred as dent-PMMA respectively base-PMMA, have been doped with different amount of TiO2 nanoparticles: 0.4, 0.6, 1.0, and 4.0% by weight. The obtained nanocomposites were structural characterized and assessed for antibacterial activity, cytotoxicity and genotoxicity. The newly obtained nanocomposites presented a good inhibitory action against the considered bacterial species-Staphylococcus aureus, good biocompatibility under 4.0% by weight. The results of the preliminary studies on cytotoxicity and genotoxicity assessment recommends the use of 0.4% TiO2 dent-PMMA and base-PMMA for CAD/CAM additive manufacturing of two-parts complete dentures/overdentures.

In this work, we proposed a new wireless sensor to contribute to research aimed at continuous monitoring of nitrate and ammonium in water, which are important agents causing water pollution, which is a very important problem today. In this research, a well-implemented application of electroanalytical sensor was achieved by combining it with the internet of things (IoT) concept, which is the most modern form of wireless data collection technique. We developed a portable IoT system and ion-selective nitrate and ammonium electrodes and monitored the nitrate and ammonium levels of the water online. The system was produced in a low-cost manner (under $25) and it enabled data acquisition without energy related problems, thanks to the support of solar energy and mobile power bank. The recovery rates of the sensors were tested with the standard addition method and response was obtained between 101.74% and 147.01%.

A coated wire calcium selective microelectrode for biological use was developed, comprising a PVC selective matrix containing calcium ionophore IV coated on copper wire, previously covered with a solid-state contact mixture. The obtained calcium microsensor presented a Nernstian answer in a concentration range of 10-1 to 10-6 mol/L. The selectivity coefficients over the main interfering ions of biological interest proved that the calcium microelectrode is highly selective. Also, the response time (6s) and repeatability have been determined. The pH variation did not significantly modify the calcium microelectrode answer, being stable over the pH range (6.7-7.3) of interest. The obtained calcium microelectrode is simple, inexpensive and able to give reliable electrochemical response, recommending itself as a solution for assessing the level of inorganic ions of the gingival crevicular fluid and saliva.

In this work, we aimed to increase the selectivity of lithium selective electrodes containing lithium ionophore VI in the membrane matrix by using 4,4,4-Trifluoro-1-phenyl-1,3-butanedione (HBTA). Potentiometric response characteristics of the prepared lithium selective electrodes were investigated. Increasing the ratio of HBTA molecule in the membrane cocktail from 0.5% to 1.5% provided a better response with respect to the lower detection limit (LDL), linear range, and selectivity. The LDL and linear range of the electrode with 1.5% HBTA were 7.6×10-6 mol L-1 and 1.0×10-1 ̶ 3.4×10-5 mol L-1 respectively, with a slope 54.3 mV/decade (R 2 = 0.9998). The potentiometric responses of all electrodes were pH-independent in the range of pH 3-12. The response time of the electrodes was less than 10 s and the lifetime was more than eight weeks. The electrode with 1.5% HBTA showed a better selectivity against sodium (1:575) and potassium (1:270) and was successfully applied for the determination of lithium levels in diluted human serum samples. The obtained potentiometric data were compared with the ICP-MS results at 98% confidence level.

We report the statistical parameters associated with the dynamic characteristics of a calcium microelectrode. The electrochemical behavior of the obtained microsensor was assessed against the main interferents.