Platinum Nanoparticle Size and Density Impacts Purine Electrochemistry with Fast-Scan Cyclic Voltammetry

Abstract

We demonstrate that the density and shape of platinum nanoparticles (PtNP) on carbon-fiber microelectrodes directly impacts detection of adenosine with fast-scan cyclic voltammetry (FSCV) . Previously, we showed that metal nanoparticle-modified carbon significantly improves adenine-based purine detection; however, how the size and shape of the particles impact electrochemical detection was not investigated. Electrochemical investigations of how the surface topology and morphology impacts detection is necessary for designing ultrasensitive electrodes and for expanding fundamental knowledge of electrode-analyte interactions. To change the density and shape of the PtNP’s on the surface, we varied the concentration of K2PtCl6 and electrodeposition time. We show that increasing the concentration of K2PtCl6 increases the density of PtNP’s while increasing the electrodeposition time impacts both the density and size. These changes manipulate the adsorption behavior which impacts sensitivity. Based on these results, an optimal electrodeposition procedure was determined to be 1.0 mg/mL of K2PtCl6 deposited for 45 s and this results in an average increase in adenosine detection by 3.5 ±0.3-fold. Interestingly, increasing the size and density of PtNPs negatively impacts dopamine detection. Overall, this work provides fundamental insights into the differences between adenosine and dopamine interaction at electrode surfaces.

Wet-Spun Porous Carbon Microfibers for Enhanced Electrochemical Detection

“…Adenosine undergoes three 2 electron/2 proton oxidations, whereas guanosine undergoes two 2 electron/2 proton reactions. In FSCV, it is well established that detection of the secondary oxidation and tertiary oxidation product (for adenosine) is more difficult than capturing the primary oxidation reaction. − Not only do analyses of adenosine and guanosine (Figure S3C,D) show enhanced primary oxidation current at PCMFs, but also we observe increases in conversion of primary oxidation product to secondary oxidation product. We speculate that this improvement in the ratio of secondary to primary peak is a result of local trapping of the purine in the pores, further catalyzing the oxidation reaction.…”

Editors’ Choice—Review—The Future of Carbon-Based Neurochemical Sensing: A Critical Perspective

“…52 Here, a holding potential of 0.2 V negates dopamine's positively charged adsorption interactions at the CF's surface at negative holding potentials, creating selective serotonin detection while the addition of a cation exchange polymer on the electrode prevents adsorption of other competing neurochemicals. One class of neurochemicals, purines, has been shown exceptional interest in recent years, 15,19,23,47,48,[53][54][55] particularly adenosine and guanosine, for their neuroprotective roles during brain injury. Several voltammetric waveforms have been optimized for adenosine, guanosine, and even co-detection (Fig.…”

“…7C). 22,23 Although these metal nanoparticles play major electrocatalytic roles in neurochemical detection, metal nanoparticles are known to be ECS Sensors Plus, 2023 2 043601 non-biocompatible and toxic if left in the body, 83 so they pose a possible health hazard when implanted in living tissue. Additionally, we have shown that altering CF's surface functionalization through nitrogen doping (Fig.…”

“…15 Surface oxygen functionality plays a vital role in catecholamine adsorption, but studies have also shown the importance of carbon surface roughness/defects to these interactions too. Tuning CF surfaces for improved dopamine detection has relied predominately on surface modification techniques such as dip coating, 19,52 drop casting, 78,79 electrodeposition, 15,21,23,43,80 CVD, 20,24,26,27,33,81,82 and plasma treatment. 15,16 Although effective, many of these modifications tend to lack robustness and efficient reproducibility due to poor electrostatic and pi-pi interactions of carbon materials onto a carbon substrate.…”

“…Some of these flaws in the carbon microstructure have led researchers to explore a variety of carbon nanostructures to enable manipulation of the neurochemical sensing platform. Various carbon nanostructures have been developed through carbon surface treatments to manipulate the surface geometry/chemical connectivity, [16][17][18][19] modification additions of carbon nanostructures onto carbon fibers, [20][21][22][23] or the synthesis of new carbon materials to focus on sought after sensor attributes. [24][25][26][27] Nanomaterials possess innate properties (high surface area, electrical and mechanical properties, etc) capable of improving neurochemical measurement kinetics, sensitivity, and, at times, selectivity depending on the analytical technique of use.…”