Highly Sensitive Phenol Biosensor Utilizing Selected Bacillus Biofilm Through an Electrochemical Method

Abstract

An eco-friendly phenol biosensor from Bacillus biofilm was prepared and investigated. The biofilm, which produced tyrosinase enzyme, was successfully immobilized on a screen-printed carbon electrode surface. A total of 72 Bacillus isolates were utilized because of their capability to produce tyrosinase enzyme in tyrosine media. Among them, Bacillus isolate code 100 was selected because it produced an adequate amount of tyrosinase enzyme and a high potentiostat current. The response surface methodology was also used to optimize the phenol sensing condition through an electrochemical method. Results showed that the optimum condition was achieved after 6 days on a phosphate buffer solution (pH of 8), with an optical density of 0.33. Furthermore, the limits of detection and quantification were 3.0 and 13 ng/L, respectively. The measurements of precision yielded a relative standard deviation of < 5%, which is remarkable. Although the biosensor material was used for 35 days, the current throughout was still maintained at 90%, indicating that the evaluated biosensor material has the potential to be used for phenol monitoring on environmental samples in the near future.

Supramolecular Ion-Exchange Resins Based on Calixarene Derivatives for Pollutant Removal from Aquatic Environmental Samples

“…Calixarene compounds were introduced by Gutsche in 1978 and afterward, the calixarene field attracted the world's attention due to its high stability, rigid structure, large-scale synthesis, and ease in modifications [117]. By using the ion template on the synthesis process of calixarene, the cavity size of calixarene could be controlled to form calix [4]arene, calix [5]arene, calix [6]arene, and calix [8]arene [65]. The chemical structures of calix[n]arene are shown in Fig.…”

“…However, the main drawback of employing Fig. 6 The chemical structures of calix[n]arene including calix [4]arene, calix [5]arene, calix [6]arene, and calix [8]arene. The "n" represents the number of the phenolic aromatic ring in the cyclic structure Fig.…”

“…Investigation of the Cr(VI) adsorption using modified Amberlite XAD-4calix [8]arene 11 has been reported [112]. The resin material was prepared through a simple stirring method for 60 h in water:ethanol 1:1 v/v media.…”

“…Due to the serious effects on human health and environment, these water pollutants should be removed or at least reduced to an acceptable concentration level. Several techniques for water treatment have been established such as adsorption, bioremediation, photocatalysis, membrane filtration, coagulation, and precipitation [127,23,51,64,72,8,49]. Among the water treatment techniques, adsorption is the most favorable process with its simple and facile operation conditions which are very suitable for commercial purposes [1,24].…”

“…Among the water treatment techniques, adsorption is the most favorable process with its simple and facile operation conditions which are very suitable for commercial purposes [1,24]. In contrast, bioremediation is a complicated process since it is very sensitive for pH, oxygen level, temperature, and light intensity and thus not favorable for commercial application [8]. The photocatalysis process is a simple process, however, it requires a long time to degrade the pollutants with strong light intensity which is not cost-effective nor feasible [64].…”