Transforming natural cells into functional biocompatible robots capable of active movement is expected to enhance the functions of the cells and revolutionize the development of synthetic micromotors. However, present cell-based micromotor systems commonly require the propulsion capabilities of rigid motors, external fields, or harsh conditions, which may compromise biocompatibility and require complex actuation equipment. Here, we report on an endogenous enzyme-powered Janus platelet micromotor (JPL-motor) system prepared by immobilizing urease asymmetrically onto the surface of natural platelet cells. This Janus distribution of urease on platelet cells enables uneven decomposition of urea in biofluids to generate enhanced chemophoretic motion. The cell surface engineering with urease has negligible impact on the functional surface proteins of platelets, and hence, the resulting JPL-motors preserve the intrinsic biofunctionalities of platelets, including effective targeting of cancer cells and bacteria. The efficient propulsion of JPL-motors in the presence of the urea fuel greatly enhances their binding efficiency with these biological targets and improves their therapeutic efficacy when loaded with model anticancer or antibiotic drugs. Overall, asymmetric enzyme immobilization on the platelet surface leads to a biogenic microrobotic system capable of autonomous movement using biological fuel. The ability to impart self-propulsion onto biological cells, such as platelets, and to load these cellular robots with a variety of functional components holds considerable promise for developing multifunctional cell-based micromotors for a variety of biomedical applications.
Disclosure: UC Davis has a research agreement and a sales-based revenue sharing agreement with United Imaging Healthcare. No other potential conflicts of interest relevant to this article exist including employment, royalties, stock options, or patents.
Small size molybdenum disulfide (MoS2) quantum dots (QDs) with desired optical properties were controllably synthesized by using tetrabutylammonium-assisted ultrasonication of multilayered MoS2 powder via OH-mediated chain-like Mo-S bond cleavage mode. The tunable up-bottom approach of precise fabrication of MoS2 QDs finally enables detailed experimental investigations of their optical properties. The synthesized MoS2 QDs present good down-conversion photoluminescence behaviors and exhibit remarkable up-conversion photoluminescence for bioimaging. The mechanism of the emerging photoluminescence was investigated. Furthermore, superior (1)O2 production ability of MoS2 QDs to commercial photosensitizer PpIX was demonstrated, which has great potential application for photodynamic therapy. These early affording results of tunable synthesis of MoS2 QDs with desired photo properties can lead to application in fields of biomedical and optoelectronics.
Hybrid light/acoustic-powered microbowl motors, composed of gold (Au) and titanium dioxide (TiO 2 ) with a structure-dependent optical modulation of both their movement and collective behavior are reported by reversing the inner and outer positions of Au and TiO 2 . The microbowl propels in an acoustic field toward its exterior side. UV light activates the photochemical reaction on the TiO 2 surface in the presence of hydrogen peroxide and the Au/TiO 2 system moves toward its TiO 2 side by self-electrophoresis. Controlling the light intensity allows switching of the dominant propulsion mode and provides braking or reversal of motion direction when TiO 2 is on the interior, or accelerated motion when the TiO 2 is on its exterior. Theoretical simulations offer an understanding of the acoustic streaming flow and self-electrophoretic fluid flow induced by the asymmetric distribution of ions around the microbowl. The light-modulation behavior along with the tunable structure also leads to the control of the swarm behaviors under the acoustic field, including expansion or compaction of ensembles of microbowls with interior and exterior TiO 2 , respectively. Such structure-dependent motion control thus paves the way for a variety of complex microscale operations, ranging from cargo transport to drug delivery in biomedical and environmental applications.
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