precise-electrochemical-sizing-individual-electro-inactive

Precise Electrochemical Sizing of Individual Electro-Inactive Particles

Nanoimpact electrochemistry enables the time-resolved in situ characterization (e.g., size, catalytic activity) of single nanomaterial units, providing a ...

University of California at Santa Barbara

Blocking electrochemistry, a subfield of nanochemistry, enables nondestructive,  measurement of the concentration, size, and size heterogeneity of highly dilute, nanometer-scale materials. This approach, in which the adsorptive impact of individual particles on a microelectrode prevents charge exchange with a freely diffusing electroactive redox mediator, has expanded the scope of electrochemistry to the study of redox-inert materials. A limitation, however, remains: inhomogeneous current fluxes associated with enhanced mass transfer occurring at the edges of planar microelectrodes confound the relationship between the size of the impacting particle and the signal it generates. These "edge effects" lead to the overestimation of size heterogeneity and, thus, poor sample characterization. In response, we demonstrate here the ability of catalytic current amplification (EC') to reduce this problem, an effect we term "electrocatalytic interruption". Specifically, we show that the increase in mass transport produced by a coupled chemical reaction significantly mitigates edge effects, returning estimated particle size distributions much closer to those observed using  electron microscopy. In parallel, electrocatalytic interruption enhances the signal observed from individual particles, enabling the detection of particles significantly smaller than is possible via conventional blocking electrochemistry. Finite element simulations indicate that the rapid chemical kinetics created by this approach contributes to the amplification of the electronic signal to restore analytical precision and reliably detect and characterize the heterogeneity of nanoscale electro-inactive materials.

Catalytic Interruption Mitigates Edge Effects in the Characterization of Heterogeneous, Insulating Nanoparticles.

Electrochemical aptamer-based (EAB) sensors encompass the only biosensor approach yet reported that is simultaneously: (1) independent of the chemical or enzymatic reactivity of its target, rendering it general; (2) continuous and real-time; and (3) selective enough to deploy  in the living body. Consistent with this,  EAB sensors supporting the seconds-resolved, real-time measurement of multiple drugs and metabolites have been reported, suggesting the approach may prove of value in biomedical research and the diagnosis, treatment, and monitoring of disease. However, to apply these devices in long-duration animal models, much less in human patients, requires that they be free of any significant pathogen load. Thus motivated, here we have characterized the compatibility of EAB sensors with standard sterilization and high-level disinfection techniques. Doing so, we find that, while many lead to significant sensor degradation, treatment with CIDEX OPA (0.55% phthalaldehyde) leads to effective disinfection without causing any detectable loss in sensor performance.

Julia Chung

Interdepartmental Program in Biomedical Science and Engineering

University of California at Santa Barbara

Precise Electrochemical Sizing of Individual Electro-Inactive Particles

Julia Chung

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Interdepartmental Program in Biomedical Science and Engineering

University of California at Santa Barbara

Precise Electrochemical Sizing of Individual Electro-Inactive Particles

Interdepartmental Program in Biomedical Science and Engineering