Redox and Label-Free Array Detection of Protein Markers in Human Serum

Abstract

A substantial outstanding challenge in diagnostics and disease monitoring is an ability to rapidly and conveniently assay for protein biomarkers within complex biological media. Label-free electroanalytical methods present, arguably, the most promising and scalable means of achieving this but, as with all label-free assays, can struggle with response selectivity issues that arise from nonspecific surface interactions. Impedimetric methods are ultrasensitive and have been applied to the quantification of a wide range of proteins but have not previously been utilized in a multiplexed format capable of operation in complex analytical fluid. Herein, we present the use of thermally cross-linked poly(ethylene glycol) (PEG) polymer sensory array interfaces in the ultrasensitive quantification of two protein markers, insulin and C-reactive protein (CRP). This was achieved with detection limits of 171 ± 19 fM and 150 ± 10 pM, respectively. Significantly, the arrays not only enable the simultaneous, fast, nonamplified, and label-free detection of both markers without reagent addition but do so with little cross talk, even in human serum. A blind analysis of 17 real patient samples generated results in excellent agreement with those obtained through a clinically approved chemiluminescence assay.

Graphene Oxide Interfaces in Serum Based Autoantibody Quantification

“…Although somewhat counterintuitive, target binding induced increase in interfacial capacitance (and thus potentially decreased Z modulus) has been noted in prior non-faradaic assaying. 7,22 The resolved assay detection limit is 1.2 ± 0.3 pM (R 2 = 0.995) ( Figure 3B), notably lower than that previously reported for this target. 8 An initial assessment of the viability of the the synuclein/GO interface to resist biofouling was made by incubating the surface in 100% artificial serum for 30 min and then washing with water prior to each measurement.…”

Single electrode biosensor for simultaneous determination of interferon gamma and lysozyme

“…Qi et al (2012) developed an electrochemical immunoassay array for the simultaneous detection of CEA and AFP by incorporating electrochemically addressing immobilization and one signal antibody strategy. Luo et al (2014) presented the use of thermally cross-linked poly (ethylene glycol) polymer sensory array interfaces for the ultrasensitive quantification of two protein markers (insulin and C-reactive protein). However, to the best of our knowledge, so far no related work has been reported on the development of a simple and reusable dual biosensor with the aim of simultaneous determination of Lys and IFN-γ.…”

Immittance Electroanalysis in Diagnostics

“…9,11 In more recent work we have demonstrated that these capabilities can be incorporated into both the analysis of real patient samples and the simultaneous detection of multiple markers. 11,[17][18][19][20][21] Faradaic EIS assays are almost exclusively based on analysing the parameter of charge transfer resistance (R ct ) obtained by fitting the acquired current signal to a Randles equivalent circuit (see SI Figure 1 for details) , 22,23 while non-faradaic analyses most typically use modulus of the impedance (|Z|), double layer capacitance (C dl ) or phase (ϕ) as sampling functions. 9,[24][25][26][27] In both approaches a phenomenological model based either on an equivalent circuit 28 or continuum scheme derived from microscopic Poisson-Nernst-Plank continuum equations (using conventional or alternative approaches for diffusional activity) [29][30][31] can be applied from which physical parameters can be extracted.…”