Performance of a dual-chamber microbial fuel cell as a biosensor for in situ monitoring Bisphenol A in wastewater

Recent advances in microbial fuel cell-based self-powered biosensors: a comprehensive exploration of sensing strategies in both anode and cathode modes

With the rapid development of society, it is of paramount importance to expeditiously assess environmental pollution and provide early warning of toxicity risks. Microbial fuel cell-based self-powered biosensors (MFC-SPBs) have emerged as a pivotal technology, obviating the necessity for external power sources and aligning with the prevailing trends toward miniaturization and simplification in biosensor development. In this case, vigorous advancements in MFC-SPBs have been acquired in past years, irrespective of whether the target identification event transpires at the anode or cathode. The present article undertakes a comprehensive review of developed MFC-SPBs, categorizing them into substrate effect and microbial activity effect based on the nature of the target identification event. Furthermore, various enhancement strategies to improve the analytical performance like accuracy and sensitivity are also outlined, along with a discussion of future research trends and application prospects of MFC-SPBs for their better developments.

Dual-signal amplified electrochemical aptasensor based on Au/MrGO and DNA nanospheres for ultra-sensitive detection of BPA without directly modified working electrode

Rapid and sensitive analysis of bisphenol A (BPA) is essential for preventing health risks to humans and animals. Hence, a signal-amplified electrochemical aptasensor without repetitive polishing and modification of working electrode was developed for BPA using Au-decorated magnetic reduced graphene oxide (Au/MrGO)-based recognition probe (RP) and DNA nanospheres (DNS)-based signal probe (SP) cooperative signal amplification. The DNS served as a signal molecule carrier and signal amplifier, while Au/MrGO acted as a signal amplifier and excellent medium for magnetic adsorption and separation. Moreover, utilizing the excellent magnetic properties of Au/MrGO eliminates the need for repetitive polishing and multi-step direct modification of the working electrode while ensuring that all detection processes take place in solution and that used Au/MrGO can be easily recycled. The proposed aptasensor exhibited not only good stability and selectivity, but also excellent sensitivity with a limit of detection (LOD) of 8.13 fg/mL (S/N = 3). The aptasensor's practicality was proven by spiking recovery tests on actual water samples and comparing the results with those detected by HPLC. The excellent sensitivity and selectivity make this aptasensor an alternative and promising avenue for rapid detection of BPA in environmental monitoring.

Plastic pollution and degradation pathways: A review on the treatment technologies

In recent years, the production of plastic has been estimated to reach 300 million tonnes, and nearly the same amount has been dumped into the waters. This waste material causes long-term damage to the ecosystem, economic sectors, and aquatic environments. Fragmentation of plastics to microplastics has been detected in the world's oceans, which causes a serious global impact. It is found that most of this debris ends up in water environments. Hence, this research aims to review the microbial degradation of microplastic, especially in water bodies and coastal areas. Aerobic bacteria will oxidize and decompose the microplastic from this environment to produce nutrients. Furthermore, plants such as microalgae can employ this nutrient as an energy source, which is the byproduct of microplastic. This paper highlights the reduction of plastics in the environment, typically by ultraviolet reduction, mechanical abrasion processes, and utilization by microorganisms and microalgae. Further discussion on the utilization of microplastics in the current technologies comprised of mechanical, chemical, and biological methods focusing more on the microalgae and microbial pathways via fuel cells has been elaborated. It can be denoted in the fuel cell system, the microalgae are placed in the bio-cathode section, and the anode chamber consists of the colony of microorganisms. Hence, electric current from the fuel cell can be generated to produce clean energy. Thus, the investigation on the emerging technologies via fuel cell systems and the potential use of microplastic pollutants for consumption has been discussed in the paper. The biochemical changes of microplastic and the interaction of microalgae and bacteria towards the degradation pathways of microplastic are also being observed in this review.

Sensitivity and reusability of a simple microbial fuel cell-based sensor for detecting bisphenol A in wastewater

Polycarbonate plastic processing wastewater contains high concentrations of bisphenol A (BPA), requiring a real-time technology to monitor wastewater containing BPA. Since the activity of electrogenic microorganisms on the anode surface of the microbial fuel cell (MFC) sensor is inhibited by exposure to contaminants, the toxicity of contaminants in wastewater can be determined by observing the variation in voltage output from the MFC sensor. The simple MFC sensor that is developed in this work exhibited a significant decrease in voltage output in BPA-containing wastewater concentration of 5-100 mg/L. Sensitivity analysis revealed that the voltage change (ΔV) was strongly correlated with the BPA concentration, with R² as high as 0.97. This study was the first to investigate the number of repeated uses of the MFC sensor, using sodium acetate as the regeneration solution for the MFC sensor, leading to a successful recovery of detection performance. However, as the number of uses increased (up to the third or fourth use), the ΔV of the MFC sensor for BPA gradually decreased and the sensitivity decreased significantly from 0.238 mV/mg/L to 0.027 mV/mg/L. In the low BPA concentration range (≦20 mg/L), the MFC sensor can be reused up to 5 times, demonstrating that the proposed MFC sensor can be reused. Microorganisms contribute to the power generation of the MFC sensor, which can be exploited in the detection of pollutants, enabling the determination of wastewater toxicity and providing early warnings of thereof. Conventional MFC sensors are complex and lack the ability to explore repeated use, so they are not easily applied to actual wastewater detection. The proposed MFC sensor has many advantages such as simplicity, rapid detection, and reusability, solving the problem of the high cost of using disposable MFC sensors and making them feasible for practical use.

Toxicity monitoring signals analysis of selenite using microbial fuel cells

Microbial fuel cells (MFCs) based biosensors are widely studied to environmental monitoring. The suitable responsive signal is important for microbial electrochemical sensors. However, the responsive signals of toxins have not been investigated in detail. Using sodium selenite as a toxic substance, the different response signals are analyzed over a concentration range from 0 to 150 mg/L in the double chambered. The output voltage and power density had the opposite trend between 0 and 2.5 mg/L and 2.5-150 mg/L. To analyze the reasonable signal of Se(IV) monitoring sensor, correlation analysis of concentrations and responsive signal data (maximum voltage, maximum power density, coulombic recovery, coulombic efficiency, and normalized energy recovery, etc.) has been accomplished. The high concentration of exogenous selenite (2.5-100 mg/L) is negatively correlated with maximum voltage (r = -0.901, p < 0.01) and max power density (r = -0.910, p < 0.01). The low concentration of exogenous selenite is positively correlated with average voltage, max power density, coulombic yield (r = 0.973, 0.999 and 0.975, respectively. p < 0.05). Furthermore, Illumina sequencing results indicate that the addition of sodium selenite solution changes the anode community structure, thereby affecting the removal efficiency of organic matter, which may be the reason why coulombic efficiency and normalized energy recovery are not suitable as sensing signal. Overall, based on the analysis of experimental data, the maximum power density is the best response signal, which provides a reference for the selection of sensor response signal based on microbial fuel cells.

Recent Implementations of Hydrogel-Based Microbial Electrochemical Technologies (METs) in Sensing Applications

Hydrogel materials have been used extensively in microbial electrochemical technology (MET) and sensor development due to their high biocompatibility and low toxicity. With an increasing demand for sensors across different sectors, it is crucial to understand the current state within the sectors of hydrogel METs and sensors. Surprisingly, a systematic review examining the application of hydrogel-based METs to sensor technologies has not yet been conducted. This review aimed to identify the current research progress surrounding the incorporation of hydrogels within METs and sensors development, with a specific focus on microbial fuel cells (MFCs) and microbial electrolysis cells (MECs). The manufacturing process/cost, operational performance, analysis accuracy and stability of typical hydrogel materials in METs and sensors were summarised and analysed. The current challenges facing the technology as well as potential direction for future research were also discussed. This review will substantially promote the understanding of hydrogel materials used in METs and benefit the development of electrochemical biosensors using hydrogel-based METs.