Magnetocatalytic Graphene Quantum Dots Janus Micromotors for Bacterial Endotoxin Detection

Abstract

Magnetocatalytic hybrid Janus micromotors encapsulating phenylboronic acid (PABA) modified graphene quantum dots (GQDs) are described herein as ultrafast sensors for the detection of deadly bacteria endotoxins. A bottom-up approach was adopted to synthesize an oil-in-water emulsion containing the GQDs along with a high loading of platinum and iron oxide nanoparticles on one side of the Janus micromotor body. The two different "active regions" enable highly efficient propulsion in the presence of hydrogen peroxide or magnetic actuation without the addition of a chemical fuel. Fluorescence quenching was observed upon the interaction of GQDs with the target endotoxin (LPS), whereby the PABA tags acted as highly specific recognition receptors of the LPS core polysaccharide region. Such adaptive hybrid operation and highly specific detection hold considerable promise for diverse clinical, agrofood, and biological applications and integration in future lab-on-chip technology.

Micro/Nanomachines: from Functionalization to Sensing and Removal

“…Self‐propelled Janus micromotor grafted with GQDs: e) schematic of the micromotor operation; f) optical image of a Janus micromotor; g) plausible mechanism of quenching of the GQDs; and h) real‐time optical visualization of fluorescent Janus micromotors in the presence of interfering saccharides. Panels (e) to (h) reproduced with permission . Self‐propelled Au‐micromotors labeled with positron‐emitting isotope: i) schematic illustration of the preparation process; j) optical and SEM images; k) phantoms for positron emission tomography in combination with computed tomography (PET‐CT) imaging; l) PET‐CT images at different time intervals as well as their activity profiles and radioactive signal.…”

“…Carbon dots, as a kind of novel carbon nanoparticles, are emerging as fluorescent probes to endow micro/nanomachines with good fluorescent features due to their outstanding optical properties, customizable surface functionalization, excellent biocompatibility, robust chemical inertness, simple and inexpensive preparation, and abundance sources in nature over organic fluorophores and semiconductor quantum dots (QDs) . Combining carbon dots with boronic acid, Escarpa and co‐workers produced fluorescent magnetocatalytic Janus micromotors functionalized with phenylboronic acid (PABA)–modified graphene quantum dots (GQDs) (Figure f) . The obtained fluorescent Janus micromotors can serve as ultrafast sensors for the detection of deadly bacteria endotoxins when being navigated in the presence of hydrogen peroxide or actuated magnetically (Figure e).…”

Visible‐Light‐Driven Janus Microvehicles in Biological Media

“…Micromotors were synthetized according to ahighly versatile oil-in-water emulsion approach. [19] This synthetic strategy allows the composition of the micromotor to be tailored for the intended purpose.Anemulsion was generated by mixing as odium dodecyl sulfate solution containing the QDs and achloroform solution of polycaprolactone (a Food and Drug Administration (FDA) approved polymer) and Fe 3 O 4 nanoparticles.P olymer droplets containing the nanoparticles were generated (27 AE 7 mms ize). Thes olution was then dried overnight at room temperature to allow for polymer solidification and micromotor generation and the drop size decreased to 17 AE 6 mm.…”

Microfluidic Lithography of Bioinspired Helical Micromotors

“…Otherwise,d riving forces depending on cascade reactions or reprogrammable logic gates and circuits could be achieved using these multilayed helical micromotors. [42][43][44] Thep repared helical micromotors have many attributes that will make them excellent as fuel-free or fuel-driven intelligent microswimmers.F or the fuel-free synthetic micromotors,i nspired by the motility of natural microorganisms, the magnetically actuated helical micromotors can navigate in avariety of biofluids and can be propelled from adistance due to the noninvasive property of the magnetic field, thus they can perform demanding tasks and remote operations while obviating the fuel requirement. [45,46] To impart our helical micromotors with the feature of magnetic field responsiveness,m agnetic nanoparticle-tagged pregel solution was employed.…”