Fluorescence Detection of miRNA-21 Using Au/Pt Bimetallic Tubular Micromotors Driven by Chemical and Surface Acoustic Wave Forces

Abstract

In this study, surface acoustic wave (SAW) systems are described for the removal of molecules that are unbound to micromotors, thereby lowering the detection limit of the cancer-related biomarker miRNA-21. For this purpose, in the first step, mass production of the Au/Pt bimetallic tubular micromotor was performed with a simple membrane template electrodeposition. The motions of catalytic Au/Pt micromotors in peroxide fuel media were analyzed under the SAW field effect. The changes in the micromotor speed were investigated depending on the type and concentration of surfactants in the presence and absence of SAW streaming. Our detection strategy was based on immobilization of probe dye-labeled single-stranded probe DNA (6-carboxyfluorescein dye-labeled-single-stranded DNA) to Au/Pt micromotors that recognize target miRNA-21. Before/after hybridization of miRNA-21 (for both w/o SAW and SAW streaming conditions), the changes in the speed of micromotors and their fluorescence intensities were studied. The response of fluorescence intensities was observed to be linearly varied with the increase of the miRNA-21 concentration from 0.5 to 5 nM under both w/o SAW and with SAW. The resulting fluorescence sensor showed a limit of detection of 0.19 nM, more than 2 folds lower compared to w/o SAW conditions. Thus, the sensor and behaviors of Au/Pt tubular micromotors were improved by acoustic removal systems.

Ultrasensitive detection of exosomal miRNA with PMO-graphene quantum dots-functionalized field-effect transistor biosensor

“…In order to better show the sensitivity of the sensor, we compared detection range and LOD of the GPPR-FET sensor with those of sensors ( Caputo et al., 2019 ; Cogal et al., 2021 ; Gao et al., 2020 ; Huang et al., 2021 ; Kim et al., 2021 ; Li et al., 2021 ; Wang et al., 2021 ; Wu et al., 2021 ). As shown in Table S2 , it can be seen that the method established in this article is superior to other sensors in terms of detection range and LOD.…”

Bubble-propelled micro/nanomotors: a robust platform for the detection of environmental pollutants and biosensing

“…Materials Advances various swimming mechanisms of micromotors have been studied and categorized as diffusiophoresis, 41 thermophoresis, 42,43 magnetophoresis, 28,44 electrophoresis, 24,31 acoustophoresis, 27,45 and bubble propulsion. [46][47][48][49][50] Some of these mechanisms have been explored by researchers for sensing applications, for example, Park et al recently demonstrated the utilization of noncatalytic polystyrene (PS) spheres towards biosensing using electric and magnetic fields.…”

“…Fig. 1 Schematic of the morphology of various micromotors designed for bubble propulsion: clockwise from the top, Janus rod, 64 jellyfish, 55 hexagon, 58 eccentric Janus, 54 tube, 45,65,66 and Janus sphere. 40,56,59,[67][68][69] Accordingly, micromotor-assisted colorimetric assays are a very cost-effective and facile technique for sample analysis within a very short time.…”

Micro‐ and Nanorobots Meet DNA

“…The application of surface acoustic waves (SAW) was demonstrated to be an effective strategy to lower the miRNA‐21 LoD by removing the unbound ssDNA probe from the microrobots’ surface. [ 56 ] Tubular Au/Pt microrobots (1.5–2 µm in diameter, ≈10 µm in length) were prepared by membrane template‐assisted electrodeposition and functionalized with a FAM‐labeled ssDNA probe. Under SAW, microrobots’ bubble‐propulsion speed in 1% H 2 O 2 increased from ≈30 to 50 µm s −1 while the lowered fluorescence intensity confirmed the release of the unbound probe.…”