Cobalt Phosphates Loaded into Iodine-Spaced Reduced Graphene Oxide Nanolayers for Electrochemical Measurement of Superoxide Generated by Cells

Abstract

Cobalt phosphate (Co3(PO4)2) has been recognized as a biomimetic superoxide anion (O2 •–) sensing material, but there is a great challenge to achieve high sensitivity due to its relatively poor conductivity. Here, a unique nanostructure is synthesized by using iodine nanospacer-impregnated reduced graphene oxide (I-rGO) layers to nest Co3(PO4)2. The role of iodine greatly enhances the density of nanoscale Co3(PO4)2 catalytic centers by separating reduced rGO layers while accelerating the interfacial electron transfer and followed transport through the directionally arranged conductive grapheme layers. The Co3(PO4)2/I-rGO sensor delivers a very good selectivity with a higher sensitivity, shorter response time, and wider linear range than that of Co3(PO4)2/rGO without the iodine nanospacers toward O2 •– detection, and also the reported Co3(PO4)2 nanorods work. Furthermore, the sensor was used to detect O2 •– generated by prostate cancer cells. This study holds promise for a high value nanoscale biomimetic sensor in practical clinical and bioresearch applications and also demonstrates a rational merit-hybrid nanocomposite design by offering critical contributions from individual components into the biomimetic sensing platform.

Atomically Dispersed Co to an End-Adsorbing Molecule for Excellent Biomimetically and Prime Sensitively Detecting O2•– Released from Living Cells

“…20 Figure 3e shows CV curves measured in 50 μM O 2 •− in 0.01 M PBS for the sCo/NG-modified electrode with oxidation and reduction peak potentials of 0.9 and 0.7 V versus Hg/Hg 2 Cl 2 / saturated KCl, respectively, while DPV curves with oxidation weak peak potentials between 0.4 and 0.6 V, respectively (Figure 3b), which are in good agreement with the standard redox reaction potential of Co 2+ /Co 3+ . 27 Besides, the relation- ship between the oxidation peak current and the scan rate is linear (Figure 3e,f), and the linear equation is obtained as y = 0.504 x + 33.622 (R 2 = 0.998), indicating a surface-controlled process toward O 2 •− oxidation. It is known that in a porous electrode, the mass transport is difficult often resulting in a diffusion limit.…”

Mn-Etched Zeolitic Imidazolate Framework-67 Nanostructures for Biomimetic Superoxide Anion Sensing

“…The CV results can specify the role of electron transfer between Mn and Co of Mn/ZIF-67, in which Mn 2+ is easier to be oxidized to Mn 3+ at first on the electrode, followed by Co 2+ to Co 3+ raising oxidation state (eqs and 2) for faster interfacial electron transfer toward O 2 •– oxidation, while Co 3+ can be reduced to Co 2+ (eq 3 ). , This is actually an electron transfer reaction-chemical reaction-chemical reaction (ECC). The detailed electrocatalysis can be expressed as follows: …”

“…•− , which showed a sensitivity of 38.62 μA μM −1 cm −2 . Zou et al 19 with a better sensitivity of 177.14 μA μM −1 cm −2 and a linear range of 0.00167−2.195 μM. However, the sensitivity and linear range of the biomimetic O 2…”

“…•− oxidation, while Co 3+ can be reduced to Co 2+ (eq 3). 19,42 This is actually an electron transfer reactionchemical reaction-chemical reaction (ECC). The detailed electrocatalysis can be expressed as follows: To further evaluate the electrochemically active surface area (ECSA) of the tested different electrodes, electrochemical double-layer capacitance (Cdl) was measured by CV in a range of 0.1∼0.2 V (Figure S4), in which there is no Faraday current.…”

“…Zhao et al utilized two-dimensional (2D) Mn 3 (PO 4 ) 2 nanosheets combined with 2D MXene nanosheets (Mn 3 (PO 4 ) 2 /MXene) to construct a sensing platform for detection of O 2 •– , which showed a sensitivity of 38.62 μA μM –1 cm –2 . Zou et al prepared a sensor based on cobalt phosphates loaded into iodine-spaced reduced graphene oxide (Co 3 (PO 4 ) 2 /I-rGO) nanolayers for detection of O 2 •– with a better sensitivity of 177.14 μA μM –1 cm –2 and a linear range of 0.00167–2.195 μM. However, the sensitivity and linear range of the biomimetic O 2 •– sensor still need further improvement.…”