In-situ growth of graphene/polyaniline for synergistic improvement of extracellular electron transfer in bioelectrochemical systems.

Graphene composite has been widely used in various bioelectrochemical systems (BES). However, it is suffered from tedious fabrication procedure and ambiguous mechanism for its effect on BES. Here, a one-step and in-situ strategy for simultaneously graphene exfoliation and aniline polymerization was developed for fabrication of graphene/PANI composite electrode (GO/PANIOS). This GO/PANIOS outperformed graphite paper (GP), GP with PANI (GP/PANI) and GP with electrochemical exfoliated graphene (GOH2SO4) in Shewanella oneidensis MR-1 inoculated BES (improved the power density output, i.e., 24, 3.4 and 5.7 times of GP , GP/PANI and GOH2SO4, respectively). Further analysis revealed a synergistic improvement on both direct and mediated extracellular electron transfer of S. oneidensis MR-1 by GO/PANIOS contributed to its performance enhancement in BES. This work not only provided a simple strategy for graphene composite fabrication, but also unveiled the underlying mechanism for its stimulation on BES, which promises new opportunity of graphene composite application in various biosystems.

Wiring Bacterial Electron Flow for Sensitive Whole-Cell Amperometric Detection of Riboflavin.

A whole-cell bioelectrochemical biosensing system for amperometric detection of riboflavin was developed. A "bioelectrochemical wire" (BW) consisting of riboflavin and cytochrome C between Shewanella oneidensis MR-1 and electrode was characterized. Typically, a strong electrochemical response was observed when riboflavin (VB2) was added to reinforce this BW. Impressively, the electrochemical response of riboflavin with this BW was over 200 times higher than that without bacteria. Uniquely, this electron rewiring process enabled the development of a biosensing system for amperometric detection of riboflavin. Remarkably, this amperometric method showed high sensitivity (LOD = 2.2 nM, S/N = 3), wide linear range (5 nM ∼ 10 µM, 3 orders of magnitude), good selectivity, and high resistance to interferences. Additionally, the developed amperometric method featured good stability and reusability. It was further applied for accurate and reliable determination of riboflavin in real conditions including food, pharmaceutical, and clinical samples without pretreatment. Both the cost-effectiveness and robustness make this whole-cell amperometric system ideal for practical applications. This work demonstrated the power of bioelectrochemical signal amplification with exoelectrogen and also provided a new idea for development of versatile whole-cell amperometric biosensors.

Enhanced power production from microbial fuel cells with high cell density culture.

Improvement of power production in a microbial fuel cell (MFC) with a high cell density culture strategy was developed. By using high cell density culture, the voltage output and power density output of the MFC were enhanced about 0.6 and 1.6 times compared to the control, respectively. Further analysis showed that riboflavin concentration in the MFC was dramatically increased from 0.1 mg/L to 1.2 mg/L by high cell density culture. Moreover, the biofilm formation on the anode surface was significantly enhanced by this new strategy. The increased accumulation of electron shuttle (riboflavin) as well as enhanced biofilm formation contributed to the improvement in anodic electrochemical activity and these factors were the underlying mechanism for MFC performance improvement by high cell density culture. This work demonstrated that high cell density culture would be a simple and practical strategy for MFC manipulation.

Enhancement of power production with tartaric acid doped polyaniline nanowire network modified anode in microbial fuel cells.

The feasibility to use tartaric acid doped PANI for MFC anode modification was determined. Uniform PANI nanowires doped with tartaric acid were synthesized and formed mesoporous networks on the carbon cloth surface. By using this tartaric acid doped PANI modified carbon cloth (PANI-TA) as the anode, the voltage output (435 ± 15 mV) and power output (490 ± 12 mW/m(2)) of MFC were enhanced by 1.6 times and 4.1 times compared to that of MFC with plain carbon cloth anode, respectively. Strikingly, the performance of PANI-TA MFC was superior to that of the MFCs with inorganic acids doped PNAI modified anode. These results substantiated that tartaric acid is a promising PANI dopant for MFC anode modification, and provided new opportunity for MFC performance improvement.

Microbial fuel cell-based biosensors for environmental monitoring: a review.

The microbial fuel cell (MFC) is an innovative technology that was initially designed to harness energy from organic waste using microorganisms. It is striking how many promising applications beyond energy production have been explored in recent decades. In particular, MFC-based biosensors are considered to be the next generation biosensing technology for environmental monitoring. This review describes recent advances in this emerging technology of MFC-based biosensors, with a special emphasis on monitoring of biochemical oxygen demand and toxicity in the environment. The progress confirms that MFC-based biosensors could be used as self-powered portable biosensing devices with great potential in long-term and remote environmental monitoring.

Correlation research on ADMA plasma levels and left ventricular function of peritoneal dialysis patients.

Asymmetric dimethylarginine (ADMA) has been involved in the development mechanism of cardiovascular disease (CVD) in patients with chronic kidney disease. The aim of this study is to investigate the relationship between the plasma ADMA levels and echocardiography, and understand the relationship between ADMA and left ventricular function. All of the patients were divided into three groups, including End-stage renal disease patients on CAPD, Conservative treatment in patients with ESRD and Control group. All the cases in the outpatient clinic or hospital at the next morning were collected fasting venous blood 2 ml. All cases were detected by American GE company Vivid7 Colour Doppler Ultrasonic Echocardiograph to detected left ventricular end-diastolic dimension (LVEDD), Left atrial diameter (LAD), Left ventricular posterior wall thickness in diastole (LVPWT), Interventricular septum thickness in diastole (IVST), left ventricular ejection fraction (LVEF). There were significant differences among all of the three groups for the GFR, urine albumin, SGA, Hb, iPTH and ALB levels. There was statistically significant difference for serum ADMA levels among three groups (F = 34.047, P = 0.000). CAPD patient plasma ADMA levels were negatively correlated with LVEF, and positively correlated with LVMI, LVM, LVEDD, LAD. Conservative treatment group had higher proportion of average artery, left ventricular hypertrophy and left ventricular mass index. The peritoneal dialysis fluid ADMA levels of CAPD patients with peritoneal were positively correlated with LVEF (r = 0.367, P = 0.046), negatively correlated with LVMI. In conclusion, ADMA may be involved in change of left ventricular structure, function, and remodeling process through a complex network.