Nanoscale Biosensors Based on Self-Propelled Objects

Abstract

This review provides a comprehensive overview of the latest developments (2016⁻2018 period) in the nano and micromotors field for biosensing applications. Nano and micromotor designs, functionalization, propulsion modes and transduction mechanism are described. A second important part of the review is devoted to novel in vitro and in vivo biosensing schemes. The potential and future prospect of such moving nanoscale biosensors are given in the conclusions.

Keywords: biosensing; micromotor; nanomotor.

Figure 1

Nano and micromotors “at work” in biosensing schemes and related applications. Catalytic micromotors: illustrating lectin-modified tubular micromotors for bacterial isolation (top part), quantum dots loaded catalytic Janus micromotors for endotoxin detection based on fluorescence quenching (middle part) and motion-based detection of glucose, xanthine and glutamate based on enzyme-powered nanowires (bottom part). Magnetic micromotors: a magnetic propelled helix carrying a sperm cell to an oocyte (top part), a fluorescent microscopy image of a spirulina-based magnetite micromotors for bioimaging (middle part) and antibody modified magnetic actuated nanowires in SERS detection operations (bottom part). Ultrasound micromotors: Lectin-modified nanowires for bacterial isolation (top part) and microRNA intracellular sensing using modified nanowires. Reprinted with permission from ref. [35], American Chemical Society; ref. [25], Wiley; ref. [16], Elsevier; ref. [36], American Chemical Society; ref. [30], The American Association for the Advancement of Science; ref. [31], American Chemical Society; ref. [32] American Chemical Society and ref. [33] American Chemical Society.

Figure 2

Catalytic micromotors for biosensing applications and related propulsion mechanisms. (a) Nanowires; (b) Tubular micromotors and (c) Janus micromotors.

Figure 3

Magnetic micromotors for biosensing applications and related propulsion mechanisms. (a) Helical swimmers; (b) Flexible nanowires and (c) Microdraggers. Part (d) shows and schematic of the propulsion mechanisms based on Helmholtz coils (left part) or permanent magnets (right part). Reproduced with permission from ref. [53] (a,d), American Chemical Society; ref. [54] (b,d), Wiley and ref. [55] (c), Wiley.

Figure 4

Ultrasound micromotors for biosensing applications and related propulsion mechanism. (a) Nanowires; (b) Iron-oxide loaded red blood cells (c) Schematic of the experimental set-up and propulsion mechanism. Reproduced with permission from ref. [32] (a), American Chemical Society; ref. [58] (b), American Chemical Society and [59] (c), American Chemical Society.

Figure 4

Ultrasound micromotors for biosensing applications and related propulsion mechanism. (a) Nanowires; (b) Iron-oxide loaded red blood cells (c) Schematic of the experimental set-up and propulsion mechanism. Reproduced with permission from ref. [32] (a), American Chemical Society; ref. [58] (b), American Chemical Society and [59] (c), American Chemical Society.

Figure 5

Transduction mechanisms for micromotors tracking in biosensing schemes. (a) Electrode impact voltammetry: schematic of a micromotor impacting a carbon microfiber electrode surface and the corresponding electrochemical signal generated. (b) Positron emission tomography. Reproduced with permission from ref. [61] (a), American Chemical Society and ref. [62] (b), American Chemical Society.

Figure 6

In vitro biosensing using self-propelled micromotors. (a) Motion-based DNA detection using PEDOT-catalase-DNA micromotors and graph showing the dependence on the speed upon DNA concentration. (b) Antibody-modified PEDOT micromotors for Bacilus globigii spore isolation and optical detection. (c) Antibody-modified PEDOT micromotors for colorimetric detection of cortisol. (d) MoS₂ micromotors for “on-off” detection of microRNA and proteins. Reproduced with permission from ref. [18] (a), Royal Society of Chemistry; ref. [65] (b), Royal Society of Chemistry; ref. [23] (c), Elsevier and ref. [28] (d), Wiley.

Figure 7

In vivo biosensing using self-propelled micromotors. (a) Spiruline-based magnetite micromotors for bioimaging, schematic of the preparation and operation. (b) Plasmonic-magnetic gyro-nanodisks for SERS bioassays. (c) microRNA detection using ultrasound propelled nanowire motors, schematic of the operation and detection in different cancer cell lines. (d) Red blood cell micromotors with quantum dots for bioimaging. Reproduced with permission from ref. [30] (a), The American Association for the Advancement of Science; ref. [31], (b) American Chemical Society; ref. [33] (c) from American Chemical Society and ref. [34] (d), Royal Society of Chemistry.