Siti Fauziyah Rahman

Dental caries is a commonly occurring dental and oral disease that is treated with a therapeutic procedure employed in dental restoration. Dental composite resins are considered a suitable material for dental restorations owing to their aesthetic appeal, biocompatibility, and favorable physical and mechanical characteristics. The aim of this work is to characterize composite resins using silicon dioxide (SiO ₂ ) filler as the main constituent, along with titanium dioxide (TiO ₂ ) as supplementary additives. The composite resins are fabricated through the silanization of fillers, followed by mixing the resin matrix to generate a paste‐like substance. The obtained pastes are molded and exposed to a 20‐s blue light. Composite I consists of 55% SiO ₂ , while composite II contains 50% SiO ₂ and 5% TiO ₂ . Several techniques are performed for characterization, including scanning electron microscopy (SEM), Fourier transform infrared (FTIR), Vickers hardness test, and polymerization shrinkage. The results showed that composite I has the highest degree of conversion and Vickers hardness values, while composite II shows the lowest shrinkage volume.

Dopamine is an important neurotransmitter involved in signal transmission to the brain. Deficiencies in dopamine are associated with various neurological disorders, such as schizophrenia, attention deficit hyperactivity disorder, and Parkinson's disease. In this study, a novel non-enzymatic electrochemical sensor for dopamine detection was developed using aluminum oxide/titanium dioxide/poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonate) (Al2O3/TiO2/PEDOT:PSS) composite modified glassy carbon electrode (GCE). Al2O3/TiO2/PEDOT:PSS composite exhibited enhanced catalytic activity for the oxidation of dopamine due to the increase of the working electrode’s surface area. Using the cyclic voltammetry (CV) method, dopamine was detected in the range of 50–1000 M in 0.1 M phosphate-buffered saline (PBS) solution at pH 7.0, with a determined limit of detection of 6 M. Since this nanocomposite modification showed low cost, easy process, and high performance, Al2O3/TiO2/PEDOT:PSS modified GCE may be a good candidate for the development of a non-enzymatic dopamine sensor.