A SERS based biosensor has been developed for isolation, detection and killing of multiple bacterial pathogens.

Graphene oxide, graphdyine oxide, and blackphosphorus coated micromotors integrating "three engines" for motion control using different stimuli such as chemical fuel, light, and magnetic fields are described. Micromotors can be massproduced by wrapping gold-sputtered polystyrene microspheres with the 2D nanomaterials, followed by simultaneous assembly of Pt or MnO 2 nanoparticles (NPs) as bubble (catalytic)-engines, Fe 2 O 3 NPs as magnetic engines, and quantum dots (QDs) as light engines. The design and composition of micromotors are key to get the desired propulsion performance. In bubble-magnetic and bubble-light mode, a built-in acceleration system allows micromotor speed to be increased up to 3.0 and 1.5 times after application of the magnetic field or light irradiation, respectively. In the bubble-magnetic-light mode, such speed increase can be combined in a single unit for on-demand braking and accelerating systems. Fluid dynamics simulations illustrate that such adaptative behavior and improved propulsion efficiency is produced by a better distribution of the fuel and thus energy propelling the micromotor by activation of the magnetic and/or light engines. The new micromotors described here, which combine multiple engines with functional nanomaterials, hold considerable promise to develop novel nanovehicles with adaptative behavior to perform complex tasks in lab-on-a-chips or dynamic micropatterning applications.

Graphene oxide/PtNPs/Fe2O3 “dual‐propelled” catalytic and fuel‐free rotary actuated magnetic Janus micromotors modified with the lanbiotic Nisin are used for highly selective capture/inactivation of gram‐positive bacteria units and biofilms. Specific interaction of Nisin with the Lipid II unit of Staphylococcus Aureus bacteria in connection with the enhanced micromotor movement and generated fluid flow result in a 2‐fold increase of the capture/killing ability (both in bubble and magnetic propulsion modes) as compared with free peptide and static counterparts. The high stability of Nisin along with the high towing force of the micromotors allow for efficient operation in untreated raw media (tap water, juice and serum) and even in blood and in flowing blood in magnetic mode. The high selectivity of the approach is illustrated by the dramatically lower interaction with gram‐negative bacteria (Escherichia Coli). The double‐propulsion (catalytic or fuel‐free magnetic) mode of the micromotors and the high biocompatibility holds considerable promise to design micromotors with tailored lanbiotics that can response to the changes that make the bacteria resistant in a myriad of clinical, environmental remediation or food safety applications.

In this work, we study the interaction of graphdiyne oxide (GDYO)-, graphene oxide (GO)-, or black phosphorous (BP)-wrapped Janus micromotors using a model system relying on a fluorescencelabeled affinity peptide, which is released upon specific interaction with a target Cholera Toxin B. Such ON−OFF−ON system allows mimicking similar processes occurring at (bio)-interfaces and to study the related sorption and desorption kinetics. The distinct surface properties of each nanomaterial play a critical role in the loading/release capacity of the peptide, greatly influencing the release profiles. Sorption obeys a secondorder kinetic model using the two-dimensional (2D) nanomaterials in connection with micromotors, indicating a strong influence of chemisorption process for BP micromotors. Yet, release kinetics are faster for GDYO and GO nanomaterials, indicating a contribution of π and hydrophobic interactions in the probe sorption (Cholera Toxin B affinity peptide) and target probe release (in the presence of Cholera Toxin B). Micromotor movement also plays a critical role in such processes, allowing for efficient operation in low raw sample volumes, where the high protein content can diminish probe loading/release, affecting the overall performance. The loading/release capacity and feasibility of the (bio)-sensing protocol are illustrated in Vibrio cholerae and Vibrio parahaemolyticus bacteria cultures as realistic domains. The new concept described here holds considerable promise to understand the interaction of micromotor with biological counterparts in a myriad of biomedical and other practical applications, including the design of novel micromotor-based sensors.

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Micromotors are man‐made nano/microscale devices capable of transforming energy into mechanical motion. The accessibility and force offered by micromotors hold great promise to solve complex biomedical challenges. This Review highlights current progress and prospects in the use of nano and micromotors for diagnosis and treatment of infectious diseases and cancer. Motion‐based sensing and fluorescence switching detection strategies along with therapeutic approaches based on direct cell capture; killing by direct contact or specific drug delivery to the affected site, will be comprehensively covered. Future challenges to translate the potential of nano/micromotors into practical applications will be described in the conclusions.

Herein, we developed a natural surface-enhanced Raman scattering (SERS) substrate based on size-tunable Au@Ag nanoparticle-coated mussel shell to form large-scale three-dimensional (3D) supercrystals (up to 10 cm2) that exhibit surface-laminated structures and crossed nanoplates and nanochannels. The high content of CaCO3 in the mussel shell results in superior hydrophobicity for analyte enrichment, and the crossed nanoplates and nanochannels provided rich SERS hot spots, which together lead to high sensitivity. Finite-difference time-domain simulations showed that nanoparticles in the channels exhibit apparently a higher electromagnetic field enhancement than nanoparticles on the platelets. Thus, under optimized conditions (using Au@AgNPs with 5 nm shell thickness), highly sensitive SERS detection with a detection limit as low as 10–9 M for rhodamine 6G was obtained. Moreover, the maximum electromagnetic field enhancement of different types of 3D supercrystals shows no apparent difference, and Au@AgNPs were uniformly distributed such that reproducible SERS measurements with a 6.5% variation (613 cm–1 peak) over 20 spectra were achieved. More importantly, the as-prepared SERS substrates can be utilized for the fast discrimination of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa by discriminant analysis. This novel Au@Ag self-assembled mussel shell template holds considerable promise as low-cost, durable, sensitive, and reproducible substrates for future SERS-based biosensors.

Herein, we describe a Janus micromotor smartphone platform for the motion-based detection of glutathione. The system compromises a universal three-dimensional (3D)-printed platform to hold a commercial smartphone, which is equipped with an external magnification optical lens (20–400×) directly attached to the camera, an adjustable sample holder to accommodate a glass slide, and a light-emitting diode (LED) source. The presence of glutathione in peroxide-rich sample media results in the decrease in the speed of 20 μm graphene-wrapped/PtNPs Janus micromotors due to poisoning of the catalytic layer by a thiol bond formation. The speed can be correlated with the concentration of glutathione, achieving a limit of detection of 0.90 μM, with percent recoveries and excellent selectivity under the presence of interfering amino acids and proteins. Naked-eye visualization of the speed decrease allows for the design of a test strip for fast glutathione detection (30 s), avoiding previous amplification strategies or sample preparation steps. The concept can be extended to other micromotor approaches relying on fluorescence or colorimetric detection for future multiplexed schemes.