Transition metal dichalcogenide-based Janus micromotors for on-the-fly Salmonella detection

Abstract

Janus micromotors encapsulating transition metal dichalcogenides (TMDs) and modified with a rhodamine (RhO)-labeled affinity peptide (RhO-NFMESLPRLGMH) are used here for Salmonella enterica endotoxin detection. The OFF–ON strategy relies on the specific binding of the peptide with the TMDs to induce fluorescence quenching (OFF state); which is next recovered due to selectively binding to the endotoxin (ON state). The increase in the fluorescence of the micromotors can be quantified as a function of the concentration of endotoxin in the sample. The developed strategy was applied to the determination of Salmonella enterica serovar Typhimurium endotoxin with high sensitivity (limits of detection (LODs) of 2.0 µg/mL using MoS2, and 1.2 µg/mL using WS2), with quantitative recoveries (ranging from 93.7 ± 4.6 % to 94.3 ± 6.6%) in bacteria cultures in just 5 min. No fluorescence recovery is observed in the presence of endotoxins with a similar structure, illustrating the high selectivity of the protocol, even against endotoxins of Salmonella enterica serovar Enteritidis with great similarity in its structure, demonstrating the high bacterial specificity of the developed method. These results revealed the analytical potential of the reported strategy in multiplexed assays using different receptors or in the design of portable detection devices. Graphical abstract

Molecular Memory Micromotors for Fast Snake Venom Toxin Dynamic Detection

“…PEG was initially chosen as a surfactant due to its biocompatibility to avoid potential α-BTx-TRITC denaturalization and neutral charge to avoid unspecific, electrostatic interactions. 48 As can be seen in Figure 2A and Video S1, the speed of the MMs increases along with the concentration of H 2 O 2 . 49 As a compromise among a higher number of motile MMs and the lowest amount of hydrogen peroxide for propulsion, we choose 10% H 2 O 2 levels at optimal.…”

Analyte Sensing with Catalytic Micromotors

“…Real-Time PCR [21,72], electrochemical biosensors [19,58,64,68,69,81,82], optical biosensors [19,58,64,69,75,81,82], enzyme-linked immunosorbent assays [22,64], the limulus amoebocyte lysate test [69,81,82] are among the analytical tools compared to catalytic micromotor sensors. The analytical performances (most often the detection limit, sometimes the accuracy) of catalytic micromotor sensors were found sometimes better [64,68,75,81,82], sometimes similar [21,22,72,75,82], and sometimes worse [19,58,69,75] than those of the classic counterparts. The outcome of such a comparison obviously depends very much on the analytical tools selected as reference points.…”

Nanoswimmers Based on Capped Janus Nanospheres

“…These biological materials may result in more biocompatible devices when combined with Janus-like core particles and they have the potential for achieving immensely accurate smart tools that have foreseeable behavior and user-engineered traits. Functionalizing particles with biological modifications has shown creative uses such as bacterial sensors [84] and even cancer-targeting delivery vectors that are cloaked from the immune system [78]. By applying the coating strategies of CJNs, also the harnessing and functionalization of entire cells has been shown to be a possibility [48].…”

“…Recently, HSs have also demonstrated potential as biosensors, as shown in the work of Pacheco et al [84]. They synthesized polymer-based Janus nanoswimmer sensors through the emulsion-mediated self-assembly of polycaprolactone (PCL) shells around transition metal dichalcogenides (TMDs) (MoS 2 or WS 2 ).…”