Focus on the performance enhancement of micro/nanomotor-based biosensors

Superhydrophobic, Anti-Freezing and Multi-Cross-Linked Wearable Hydrogel Strain Sensor for Underwater Gesture Recognition

Conductive hydrogel is considered to be one of the most potential sensing materials for wearable strain sensors. However, both the hydrophilicity of polymer chains and high water content severely inhibit the potential applications of hydrogel-based sensors in extreme conditions. In this study, a multicross-linked hydrogel was prepared by simultaneously introducing a double-network matrix, multiple conductive fillers, and free-moving ions, which can withstand an ultralow temperature below -80 °C. A superhydrophobic Ecoflex layer with a water contact angle of 159.1° was coated on the hydrogel using simple spraying and laser engraving methods. Additionally, the smart glove integrating five hydrogel strain sensors with a microprocessor was developed to recognize 12 types of diving gestures and synchronously transmit recognition results to smartphones. The superhydrophobic and antifreezing hydrogel strain sensor proposed in this study emerges promising potentials in wearable electronics, human-machine interfaces, and underwater applications.

Synergistic self-driven and heterogeneous effect of a biomass-derived urchin-like Mn3O4/C3N4 Janus micromotor catalyst for efficient degradation of carbamazepine

It is well known that obtaining efficient carbamazepine degradation materials or rapid carbamazepine-removal methods is still a challenge in the field of environmental remediation. Hence, the present study aimed to concurrently address these issues by combining a self-driven, heterostructured and low-cost biomass-templated urchin-like Janus micromotor catalyst for highly efficient carbamazepine degradation. The catalyst could autonomously move in a circle-like motion pattern via O2 bubbles generated from the Mn3O4-catalyzed decomposition of H2O2 with a velocity of 223.5 ± 7.0 μm s-1 in 1% H2O2. Benefiting from the well-structured heterojunction at the interface of C3N4 and Mn3O4, carbamazepine (CBZ) was degraded by 61% in 100 min under sunlight irradiation. In addition, density functional theory calculation results proved that the formation of the heterojunction structure promoted the generation of photo-generated carriers. Thus, the presented method provides a promising pathway for the rational construction and preparation of movable catalysts for the efficient removal of organic pollutants from wastewater.

Real-Time Detection of Multiple Intracellular MicroRNAs using an Ultrasound-Propelled Nanomotor-Based Dynamic Fluorescent Probe

Multiple intracellular microRNA (miRNA) detection is essential for disease diagnosis and management. Nonetheless, the real-time detection of multiple intracellular miRNAs has remained challenging. Herein, we have developed an ultrasound (US)-powered nanomotor-based dynamic fluorescent probe for the real-time OFF-ON fluorescent determination of multiple intracellular miRNAs. The new probe relies on the utilization of multicolored quantum dot (QD)-labeled single-stranded DNA (ssDNA)/graphene oxide (GO)-coated US-powered gold nanowire (AuNW) nanomotors. The fluorescence of QDs is quenched due to π-π interactions with the GO. Upon binding to target miRNAs, the QDs-ssDNA is now distant from the AuNWs, resulting in effective OFF-ON QD fluorescence switching. Compared with conventional passive probes, the dynamic fluorescent probe enhances probe-target interactions by using the US-propelled nanomotor, resulting in exceptionally efficient and prompt hybridization. Simultaneous quantitative analysis of miR-10b and miR-21 in vitro can be achieved within 15 min with high sensitivity and specificity. Additionally, multicolor QDs provide strong signal intensity and multiplexed detection, enabling one-step real-time discrimination between cancer cells (A549) and normal cells (L02). The obtained results are in good agreement with those from qRT-PCR. This dynamic fluorescent probe based on a nanomotor and QDs enables rapid "on the move" specific detection of multiple intracellular miRNAs in intact cells, facilitating real-time monitoring of diverse intracellular miRNA expression, and it could pave the way for novel applications of nanomotors in biodetection.

Polyoxometalate-Nanozyme-Integrated Nanomotors (POMotors) for Self-Propulsion-Promoted Synergistic Photothermal-Catalytic Tumor Therapy

Enzyme-powered nanomotors have demonstrated promising potential in biomedical applications, especially for catalytic tumor therapy, owing to their ability of self-propulsion and bio-catalysis. However, the fragility of natural enzymes limits their environmental adaptability and also therapeutic efficacy in catalysis-enabled tumor therapy. Herein, polyoxometalate-nanozyme-based light-driven nanomotors were designed and synthesized for targeted synergistic photothermal-catalytic tumor therapy. In this construct, the peroxidase-like activity of the P2 W18 Fe4 polyoxometalates-based nanomotors can provide self-propulsion and facilitate their production of reactive oxygen species thus killing tumor cells, even in the weakly acidic tumor microenvironment. Conjugated polydopamine endows the nanomotors with the capability of light-driven self-propulsion behavior. After 10 min of NIR (808 nm) irradiation, along with the help of epidermal growth factor receptor antibody, the targeted accumulation and penetration of nanomotors in the tumor enabled highly efficient synergistic photothermal-catalytic therapy. This approach overcomes the disadvantages of the intrinsically fragile nature of enzyme-powered nanomotors in physiological environments and, more importantly, provides a motility-behavior promoted synergistic anti-tumor strategy.

Enzyme-free electrochemical sensor platforms based on transition metal nanostructures for clinical diagnostics

The detection of emergent biomarkers is of key significance in numerous clinical, biological, and biomedical fields. Specifically, the design and development of potent electrochemical lactic acid and glucose sensing platforms are especially in great demand in a variety of industries, including those involved in clinical analysis, biomedicine, biological, food, cosmetics, pharmaceuticals, leather, sports, and chemical industries. Nanostructured transition metal-derived materials have opened the door to electrochemical sensors and biosensors due to their advantages of high surface-to-volume ratio, surface reaction activity, catalytic activity, and strong adsorption capability. The primary aim of the present minireview is to highlight the advancement of enzyme-free electrochemical sensor platforms based on transition metal-derived nanostructures with high electrocatalytic activity and sensing performance towards lactic acid and glucose in practical samples. The preparation approaches, structural and composition monitoring, fabrication of sensing electrodes, catalytic activity, sensing performance in real samples, and the exploration of sensing mechanisms are majorly concentrated on in most of our recent research studies. Moreover, state-of-the-art transition metal-derived nanostructure-derived electrochemical sensor platforms, critical comparison of the analytical performance of the sensor platforms, and the future perspectives of the enzyme-free electrochemical sensor for clinical diagnostics are described.