A self-powered amperometric lactate biosensor based on lactate oxidase immobilized in dimethylferrocene-modified LPEI

Abstract

Lactate is an important biomarker due to its excessive production by the body during anerobic metabolism. Existing methods for electrochemical lactate detection require the use of an external power source to supply a positive potential to the working electrode of a given device. Herein we describe a self-powered amperometric lactate biosensor that utilizes a dimethylferrocene-modified linear poly(ethylenimine) (FcMe2-LPEI) hydrogel to simultaneously immobilize and mediate electron transfer from lactate oxidase (LOx) at the anode and a previously described enzymatic cathode. Operating as a half-cell, the FcMe2-LPEI electrode material generates a jmax of 1.51 ± 0.13 mAcm(-2) with a KM of 1.6 ± 0.1 mM and a sensitivity of 400 ± 20 μAcm(-2)mM(-1) while operating with an applied potential of 0.3 V vs. SCE. When coupled with an enzymatic biocathode, the self-powered biosensor has a detection range between 0mM and 5mM lactate with a sensitivity of 45 ± 6 μAcm(-2)mM(-1). Additionally, the FcMe2-LPEI/LOx-based self-powered sensor is capable of generating a power density of 122 ± 5 μWcm(-2) with a current density of 657 ± 17 μAcm(-2) and an open circuit potential of 0.57 ± 0.01 V, which is sufficient to act as a supplemental power source for additional small electronic devices.

Modeling Carbon Nanotube Connectivity and Surface Activity in a Contact Lens Biofuel Cell

“…5A) show a typical reversible dimethylferrocene redox couple with an oxidation peak at 0.25 V vs. SCE and an enzyme-catalyzed lactate oxidation onset potential at -0.025 V vs. SCE. These results are consistent with those recently reported in a self-powered, FcME 2 -LPEI-mediated lactate sensor [24]. The Fig.…”

“…The cathode was larger in an attempt to overcome cathode limitations. redox polymer [47] that has proven to be very effective at mediating electron transfer for oxidation of glucose [47], fructose [48], ethanol [49], and lactate [24]. Anode-modifying solutions containing 70.5% v/v FcME 2 -LPEI (10 mg ml -1 in deionized water), 26% v/v LOx from Pediococcus sp.…”

“…However, the use of adsorbed NAD + as a cofactor results in inherent instability due to desorption of poly(methylene green) and adds significant complexity with respect to substrate and cofactor diffusion. As a potentially simpler alternative anode system, we recently reported [24] a high current density selfpowered lactate sensor that utilizes a flavin adenine dinucleotide (FAD)-dependent lactate oxidase (LOx) that was "wired" to an electrode surface using a dimethylferrocene-modified linear poly(ethylenimine) (FcMe 2 -LPEI) redox polymer, where the redox polymer simultaneously immobilizes the enzyme at the electrode surface and facilitates rapid electron transfer between the enzyme's active site and electrode. While using this system produced a simpler, more stable anode, the cathode continued to be problematic, requiring a high enzyme and CNT loading as well as a larger projected surface area to match the anodic current.…”

Improving the performance of lactate/oxygen biofuel cells using a microfluidic design

“…This data showed the FcMe 2 -LPEI/LOx electrodes preserving 85% of its maximum catalytic activity at pH 7.4 while preserving only 45% of the maximum catalytic activity at pH 5.6. For this reason, we predicted that the µBFC could have a higher current density [24]. Figure 6shows the polarization and power density curves comparison between different µBFC evaluated using 10 mM lactate highlighting the performance obtaining with µBFC in pH 7.4.Importantly, another advantage of the μBFC design is that it reduces the effects of fuel crossoveras shown in our previous work [15], which could explain the decrease in the OCPobserved for the single compartment BFCs.Also, theμBFC design allowedfor the operation of the device in the absence of a membrane, enabling the independent use of different electrolytes for the bioanode and biocathode whichimproves enzymatic catalytic activity.…”

Self‐powered polymer–metal oxide hybrid solar cell for non‐enzymatic potentiometric sensing of bilirubin

“…Addressing these key issues, considerable interest is diverted towards development of sensitive, robust, portable and inexpensive self‐powered biosensing devices. Katz, Bückmann, and Willner () proposed self‐powered sensor (SPS) device based on the biofuel cell principle for the detections of cholesterol (Sekretaryova et al, ), glucose (Katz et al, ; Pinyou et al, ), lactate (Hickey, Reid, Milton, & Minteer, ; Katz et al, ), acetaldehyde (Zhang, Zhou, & Dong, ), ascorbic acid (Zloczewska et al, ), proteins (Han et al, ; Wang et al, ), drugs/antibiotics (Conzuelo, Vivekananthan, Pöller, Pingarrón, & Schuhmann, ; Zhou et al, ) and explosives (Germain, Arechederra, & Minteer, ). The energy required is self‐generated by the enzyme‐substrate redox reactions occurring at two different electrodes, and observed current is proportional to the substrate concentration.…”