RESUMEN
The use of alkaline phosphatase (ALP) as a biomarker in some diseases including hepatitis, obstructive jaundice, osteoblastic bone cancer, and osteomalacia is important in clinical diagnosis. Furthermore, ALP activity detection is an essential hot topic in environmental monitoring, biomedical research, and other research fields. In this study, a novel "signal-on" photoelectrochemical (PEC) biosensor based on the ALP-catalyzed phosphorylation reaction was designed to sensitively detect ALP activity. In this design, ascorbic acid-an electron donor-was catalytically produced by ALP from l-ascorbic acid 2-phosphate trisodium salt in situ, which results in an increased photocurrent response signal. For immobilizing the ALP on the electrode surface, poly diallyl dimethyl ammonium chloride was used for the conjugation of ALP, and titanium dioxide (TiO2)-a photoactive material-and graphite-like carbon nitride (g-C3N4) nanocomposites were prepared and characterized. TiO2 attached on g-C3N4 plays an important role for the biosensing purpose due to their good biocompatibility and chemical/thermal stability, while g-C3N4 provides the PEC response signal. Furthermore, the prepared TiO2/g-C3N4 nanocomposites can effectively suppress electron-hole recombinations, improve the excitation conversion efficiency, and make the best use of solar energy. The PEC biosensor for ALP activity detection displays a detection limit of 0.03 U L-1 (S/N = 3), which offers a new route for the ALP activity assay in human serum samples.
RESUMEN
Various experimental conditions were tested for the green extract process of corrosion inhibitor from lychee fruit waste, and the optimal extract parameters were selected using potentiodynamic polarization. The best inhibition effect of the ethanol extract of lychee's peel and seed by ultrasound for 1.5â¯h (EELPS) for mild steel in 0.5â¯M HCl was obtained at 600â¯mg/L using electrochemical and weight loss measurements. Theoretical calculations illustrate the adsorption sites and adsorption behavior of effective compounds. Due to the existence of hydroxyl groups and phenol rings in the main components, EELPS is considered to be a good inhibitor.
RESUMEN
Longan seed and peel were extracted and used for impeding the corrosion of mild steel in hydrochloric acid solution. Experimental analyses indicate that the water extract of Longan's seed and peel, a mixed type inhibitor, can be chemically adsorbed onto the steel surface, and its inhibition effect rises with increasing extract concentration. To understand the adsorption mechanism and the contributions of the four main compounds of the extract to corrosion protection effect, quantum chemical methods and infrared spectrum were also employed. Theoretically, four main antioxidant compounds were regarded as effective components in the water extract of Longan's seed and peel.
RESUMEN
The use of the cosmetic ingredient cocamidopropylamine oxide (CAO) to inhibit the corrosion of steel in 0.5mol/LHCl is investigated. Electrochemical and weight loss methods were used to evaluate the inhibiting effect of CAO and the influences of inhibitor concentration and temperature were determined. It was found that CAO acted as a mix-type inhibitor and was adsorbed chemically onto the steel in HCl solution, and the maximum inhibition efficiency was found at critical micelle concentration (CMC) of CAO in tested corrosive media. Moreover, it was speculated that relationships of the two adsorption sites of the inhibitor and steel surface were different.
