Screen-printed carbon electrode (SPCE) is one of the most interesting designs to combine a working (from carbon based material), reference, and counter electrode in a single-printed substrate. SPCE has been used in many electrochemical measurements due to its advantages for analysis in microscale. This paper summarises the main information about SPCE fabrication from the material and fabrication technique aspect on the flat substrate based on the work that has been published in the last 30 years. The success of SPCE fabrication is highly dependent on the composition of conductive ink which consists of conductive materials, binder, and solvents; substrate; and fabrication techniques. Among the carbon-based materials, the most widely used for SPCE fabrications are graphite, graphene, and carbon nanotubes. The frequent binder used are polymer-based materials such as polystyrene, polyaniline, poly 3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS), and polyvinyl chloride. The solvents used for SPCE fabrication are varied including water and various organic solvents. The main characteristics of the SPCE substrate should be inert in order to avoid any interferences during electrochemical measurements. The screen printing and inkjet printing technique are preferred for SPCE fabrication due to easy fabrication and the possibility for mass production of SPCE.

A glassy carbon electrode modified with electrochemically reduced graphene oxide (ErGO) and poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was developed for the 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 the detection limits of 1.08 µM and the quantitation limit of 3.61 µM. This sensor also showed good reproducibility for uric acid detection in the artificial saliva in 5 consecutive days measurements. This device was successfully used to analyze uric acid in the artificial saliva as well as in human saliva sample using standard addition method.

A 2D-TiO 2 nanosheet material (as a film deposit of approximately 1 mm thickness on glassy carbon) is employed to host ferroceneboronic acid receptor molecules. It is suggested that the negative surface charge on 2D-TiO 2 nanosheets allows weak binding of ferroceneboronic acid, which can then be employed to detect fluoride, glucose, or fructose. The nature of the aqueous electrolyte is shown to strongly affect the ferroceneboronic acidhost interaction. In the presence of di-sodium sulfate stable reversible voltammetric responses are observed. In the presence of fluoride loss of the ferroceneboronic acid occurs probably due to weakening of the boron-titanate interaction. For glucose and for fructose "bound" and "unbound" states of the ferroceneboronic acid are observed as long as fast square wave voltammetry is employed to capture the "bound" state before decomplexation can occur. It is shown that this kinetic selectivity is highly biassed towards fructose and essentially insensitive to glucose.

Antioxidant properties of clove bud have been widely studied due to its potential use in the pharmaceuticals field. One of the chemical bioactive compounds that show antioxidant activity is flavonoid. Our study revealed that the flavonoid content of ethanol-derived extract of clove bud was approximately 93.245 mg QE/100 gram. Less is known regarding the mode of actions of antioxidant from clove bud in cellular systems. In this study, we used model organism yeast Saccharomyces cerevisiae to study the action of antioxidant activity in cellular systems. We found that ethanol-derived clove bud extract (100 ppm) enhanced cells viability following H2O2-induced oxidative stress. Interestingly, clove bud extract increased yeast-antioxidative stress tolerance phenotype in a dose-independent manner. Suggesting, prooxidant activity of clove bud extract. Mitochondria have been known to involve in oxidative stress tolerance mechanisms primarily via mitochondrial adaptive ROS-signaling. Our data revealed that yeast mitochondrial membrane potential was unchanged following 100 ppm extract treatment yet significantly increased in higher extract treatment. Our study indicated that 100 ppm extract-supplementation in yeast culture resulted in a higher survival rate of yeast after 15-days of incubation, compared to that without extract treatments. We suggest that clove bud extract (100 ppm) could enhance oxidative stress tolerance phenotype in yeast S. cerevisiae, which then attributed on life span extension through its ROS scavenging activity. Further study must be conducted to confirm the underlying mechanisms of clove bud extract both physiologically and genetically.