Tanmay Kulkarni

Enzymatic Glucose Biofuel Cell and its Application

Biofuel cells have received significant attention in the last few decades due to its potential application as alternative energy sources and advantages over conventional fuel cells. This review summarizes different types of glucose biofuel cells with emphasis on enzymatic glucose biofuel cells. Unlike conventional fuel cells, which use fuel such as ethanol, methanol, formic acid, etc. to generate electricity, enzymatic glucose biofuel cells convert chemical energy stored in glucose into electricity. Energy generating from complex sugar is now possible due to the most common glucose selective enzymes, Glucose Oxidase (GOx) and Pyroquinoline Quinone Glucose Dehydrogenase (PQQ-GDH). Glucose as a fuel source is cost-efficient because it is readily abundant and offers a clean source of power. The micro-power generated from the selective glucose/ O2 redox reactions can be used to power ultra-low powered bioelectronic devices. In addition, in vivo glucose biofuel cell implantations and potential applications are highlighted.

A self-powered glucose biosensing system.

A self-powered glucose biosensor (SPGS) system is fabricated and in vitro characterization of the power generation and charging frequency characteristics in glucose analyte are described. The bioelectrodes consist of compressed network of three-dimensional multi-walled carbon nanotubes with redox enzymes, pyroquinoline quinone glucose dehydrogenase (PQQ-GDH) and laccase functioning as the anodic and cathodic catalyst, respectively. When operated in 45 mM glucose, the biofuel cell exhibited an open circuit voltage and power density of 681.8 mV and 67.86 µW/cm(2) at 335 mV, respectively, with a current density of 202.2 µA/cm(2). Moreover, at physiological glucose concentration (5mM), the biofuel cell exhibits open circuit voltage and power density of 302.1 mV and 15.98 µW/cm(2) at 166.3 mV, respectively, with a current density of 100 µA/cm(2). The biofuel cell assembly produced a linear dynamic range of 0.5-45 mM glucose. These findings show that glucose biofuel cells can be further investigated in the development of a self-powered glucose biosensor by using a capacitor as the transducer element. By monitoring the capacitor charging frequencies, which are influenced by the concentration of the glucose analyte, a linear dynamic range of 0.5-35 mM glucose is observed. The operational stability of SPGS is monitored over a period of 63 days and is found to be stable with 15.38% and 11.76% drop in power density under continuous discharge in 10mM and 20mM glucose, respectively. These results demonstrate that SPGSs can simultaneously generate bioelectricity to power ultra-low powered devices and sense glucose.

Highly Selective and Sensitive Self-Powered Glucose Sensor Based on Capacitor Circuit

Enzymatic glucose biosensors are being developed to incorporate nanoscale materials with the biological recognition elements to assist in the rapid and sensitive detection of glucose. Here we present a highly sensitive and selective glucose sensor based on capacitor circuit that is capable of selectively sensing glucose while simultaneously powering a small microelectronic device. Multi-walled carbon nanotubes (MWCNTs) is chemically modified with pyrroloquinoline quinone glucose dehydrogenase (PQQ-GDH) and bilirubin oxidase (BOD) at anode and cathode, respectively, in the biofuel cell arrangement. The input voltage (as low as 0.25 V) from the biofuel cell is converted to a stepped-up power and charged to the capacitor to the voltage of 1.8 V. The frequency of the charge/discharge cycle of the capacitor corresponded to the oxidation of glucose. The biofuel cell structure-based glucose sensor synergizes the advantages of both the glucose biosensor and biofuel cell. In addition, this glucose sensor favored a very high selectivity towards glucose in the presence of competing and non-competing analytes. It exhibited unprecedented sensitivity of 37.66 Hz/mM.cm2 and a linear range of 1 to 20 mM. This innovative self-powered glucose sensor opens new doors for implementation of biofuel cells and capacitor circuits for medical diagnosis and powering therapeutic devices.

Self-powered glucose biosensor operating under physiological conditions

Here we describe the characterization of a self-powered glucose biosensor comprising of a multi-walled carbon nanotubes (MWCNTs) modified with pyroquinoline quinone glucose dehydrogenase (PQQ-GDH) bioanode and bilirubin oxidase biocathode at physiological conditions. The assembly shows an enhancement in peak power and current densities as compared to the self-powered glucose biosensor comprising of PQQ-GDH bioanode and laccase biocathode. The assembly produced a maximum open circuit voltage of 480.1 mV and short circuit current density of 640 μA/cm2 with a peak power density of 89.27 μW/cm2. The self-powered glucose biosensor exhibited an extended linear dynamic range of 0.1 mM to 35 mM with a sensitivity of 12.221 Hz/mM cm2. The use of bilirubin oxidase as the cathodic enzyme in addition to the design of biofuel cell assembly makes it a viable candidate as a potential power source for bioelectronics devices.

Application of Semipermeable Membranes in Glucose Biosensing

Glucose biosensors have received significant attention in recent years due to the escalating mortality rate of diabetes mellitus. Although there is currently no cure for diabetes mellitus, individuals living with diabetes can lead a normal life by maintaining tight control of their blood glucose levels using glucose biosensors (e.g., glucometers). Current research in the field is focused on the optimization and improvement in the performance of glucose biosensors by employing a variety of glucose selective enzymes, mediators and semipermeable membranes to improve the electron transfer between the active center of the enzyme and the electrode substrate. Herein, we summarize the different semipermeable membranes used in the fabrication of the glucose biosensor, that result in improved biosensor sensitivity, selectivity, dynamic range, response time and stability.

Hyperglycemic Challenge and Distribution of Adipose Tissue in Obese Baboons

Background Blood glucose levels regulate the rate of insulin secretion, which is the body’s mechanism for preventing excessive elevation in blood glucose. Impaired glucose metabolism and insulin resistance have been linked to excess body fat composition. Here, we quantify abdominal muscle and abdominal adipose tissue compartments in a large nonhuman primate, the baboon, and investigate their relationship with serum glucose response to a hyperglycemic challenge. Methods Five female baboons were fasted for 16 hours prior to 90 minute body imaging experiment that consisted of a 20-min baseline, followed by a bolus infusion of glucose (500mg/kg). The blood glucose was sampled at regular intervals. The total volumes of the muscle, visceral and subcutaneous adipose tissue were measured. Results and discussion We found that adipose tissue composition predicted fluctuations in glucose responses to a hyperglycemic challenge of a non-human primate. Animals with higher visceral adiposity showed significantly reduced glucose elimination. The glucose responses were positively correlated with body weight, visceral and muscle fat (p < 0.005). Polynomial regression analysis showed that body weight, visceral and muscle were significant Conclusions These results reveal the similarity between humans and baboons with respect to glucose metabolism and strengthen the utility of baboon for biomedical research.

Characteristics of Two Self-Powered Glucose Biosensors

Here, we describe the characterization of a self-powered glucose biosensor that is capable of generating electrical power from the biochemical energy stored in glucose to serve as the primary source of power for microelectronic devices. One self-powered glucose biosensor is based on multi-walled carbon nanotubes modified with pyroquinoline quinone glucose dehydrogenase (PQQ-GDH) and laccase at the bioanode and biocathode, respectively, whereas the other employed bilirubin oxidase at the biocathode. The self-power glucose biosensor employing the bilirubin oxidase biocathode operated at physiological condition and produced an enhanced peak power and current densities as compared with the self-powered glucose biosensor comprising of PQQ-GDH bioanode and laccase biocathode. The self-powered glucose biosensor employing bilirubin oxidase produced an average open circuit voltage of 0.480 V and delivered an average short circuit current density of 0.64 mA/cm2 with a peak power density of 0.089 mW/cm2. In addition, this self-powered glucose biosensor exhibited a linear dynamic range of 0.5–35 mM with a sensitivity of 12.221 Hz/mM

Dynamic modeling of direct electron transfer PQQ-GDH MWCNTs bioanode function

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A self-powered glucose biosensor based on pyrolloquinoline quinone glucose dehydrogenase and bilirubin oxidase operating under physiological conditions

cm2. The use of bilirubin oxidase as the biocathodic enzyme makes it a viable candidate as a potential power source for in vivo applications.

A microfabricated low-cost Au nanotip pyramidal electrode array using anisotropic etching for enhanced performance of a glucose biosensor

Herein a system capable of simultaneously sensing glucose and harvesting sufficient energy to power a digital device is presented. This system is powered by an enzymatic glucose biofuel cell consisting of pyroloquinoline quinone glucose dehydrogenase (PQQ-GDH) modified bioanode and bilirubin oxidase modified biocathode. The electrical parameters from a single biofuel cell were amplified to 1.4 V using a charge pump circuit consisting of a capacitive element that senses glucose. Further a steady output DC supply of 3.2 V was obtained by interfacing a step up DC-DC converter circuit to the charge pump circuit. Such a system simultaneously senses glucose and harvests energy in various glucose concentrations operating under physiological conditions (37 °C and pH 7.4). The novel system shows a promising future for healthcare systems industry.