Breaking the barrier to biomolecule limit-of-detection via 3D printed multi-length-scale graphene-coated electrodes

Abstract

Sensing of clinically relevant biomolecules such as neurotransmitters at low concentrations can enable an early detection and treatment of a range of diseases. Several nanostructures are being explored by researchers to detect biomolecules at sensitivities beyond the picomolar range. It is recognized, however, that nanostructuring of surfaces alone is not sufficient to enhance sensor sensitivities down to the femtomolar level. In this paper, we break this barrier/limit by introducing a sensing platform that uses a multi-length-scale electrode architecture consisting of 3D printed silver micropillars decorated with graphene nanoflakes and use it to demonstrate the detection of dopamine at a limit-of-detection of 500 attomoles. The graphene provides a high surface area at nanoscale, while micropillar array accelerates the interaction of diffusing analyte molecules with the electrode at low concentrations. The hierarchical electrode architecture introduced in this work opens the possibility of detecting biomolecules at ultralow concentrations.

Ultrasensitive Dopamine Detection with Graphene Aptasensor Multitransistor Arrays

“…Biosensors developed and optimized based on in vitro assays tend to underperform in biological samples, losing sensitivity and selectivity. This underperformance, also observed in previous ion-sensitive dopamine biosensors [8], [9], is usually due to a high number of interferent molecules and ions typically not found in optimized buffers and the reduction of the Debye length due to the increased shielding effect of the biological solution’s additional counter-ions [44]. Thus, to evaluate the performance of our gMTAs in a physiological scenario, dopamine detection experiments were performed in biological CSF and brain homogenate samples.…”

“…The dopamine LOD of 1 aM (10 −18 ) obtained with our gMTAs is 3 orders of magnitude lower than the lowest LOD ever reported for any dopamine sensor, currently at 0.5 fM (10 −15 ) [8], [9], and several orders of magnitude lower than the LOD attained with the majority of previous methodologies, as summarized in the Supporting Information (Table S1). Additionally, the sensors currently presenting the lowest dopamine LOD, although based on organic field-effect transistors [12] or graphene electrodes [13], rely on voltammetric electrochemical measurements or require the addition of labels/reporters.…”

“…Novel emerging approaches have focused on miniaturized biosensors, primarily based on catalytic and electrochemical reactions, but have mostly lacked relevant selectivity and sensitivity [6], [7]. At present, the limit of detection (LOD) for dopamine sits at 0.5 fM [8], [9], but most methods have reduced sensitivity, and narrow working ranges between nM and μM concentrations [6], [7]. Additionally, many novel biosensors for dopamine and other neurotransmitters detection have complicated fabrication processes [6], [7] that pose constraints on miniaturization and integration, thus limiting dissemination, reproducibility, and the development of relevant research tools and point-of-care devices.…”

Recent Advances in 3D Printing of Biomedical Sensing Devices

“…Commercial SPR biochip [154] Self-assembled monolayered Au 1-1000 ng mL −1 18.1 ng mL −1 Assay time ≈14 min. Sensing with buffer solution and human serum Microfabrication [155] Self-assembled monolayer Au 0-4 µg mL −1 0.2 µg mL −1 Single-use biosensor, sensing with serum samples and good sensitivity 3D Printing (AJP) [49] Dopamine Micropillar array electrode 100 am-1 mm 500 am Low LoD ≈ 500 attomoles, breaking the barrier described in literature [47] through multi-length-scale electrode structure. Rapid prototyping capability and waste minimization due to small microfluidic volume required for testing.…”

“…[47,48] The AJP method was employed to create a micropillar-based hierarchical structure where sintered particles offered excellent surface topography for the attachment of nanomaterials such as graphene, resulting in the rapid detection of dopamine at sensitivities down to femtomolar concentrations. [49] Although lithography can create 3D hierarchical structures/architectures, the techniques are typically complex and more difficult to implement [50] compared to those by 3D printing methods such as two photon polymerization or 2PP [51] and AJP. [52] Additional advantages include high reproducibility, robustness, and reliability of the biosensors.…”