Inspired by the swimming of natural microorganisms, synthetic micro‐/nanomachines, which convert energy into movement, are able to mimic the function of these amazing natural systems and help ...humanity by completing environmental and biological tasks. While offering autonomous propulsion, conventional micro‐/nanomachines usually rely on the decomposition of external chemical fuels (e.g., H2O2), which greatly hinders their applications in biologically relevant media. Recent developments have resulted in various micro‐/nanomotors that can be powered by biocompatible fuels. Fuel‐free synthetic micro‐/nanomotors, which can move without external chemical fuels, represent another attractive solution for practical applications owing to their biocompatibility and sustainability. Here, recent developments on fuel‐free micro‐/nanomotors (powered by various external stimuli such as light, magnetic, electric, or ultrasonic fields) are summarized, ranging from fabrication to propulsion mechanisms. The applications of these fuel‐free micro‐/nanomotors are also discussed, including nanopatterning, targeted drug/gene delivery, cell manipulation, and precision nanosurgery. With continuous innovation, future autonomous, intelligent and multifunctional fuel‐free micro‐/nanomachines are expected to have a profound impact upon diverse biomedical applications, providing unlimited opportunities beyond one's imagination.
Fuel‐free synthetic micro‐/nanomachines powered by external stimuli are able to swim efficiently in biologically relevant environments. Tremendous progress made in the past decade to develop different synthesis strategies for designing and fabricating fuel‐free micro‐/nanomotors with different functionalities is reviewed. These artificial nanomachines can achieve predetermined tasks in biomedical applications.
The bioinspired micropatterns exhibit outstanding capacity in controlling and patterning microdroplets, which have offered new functionalities and possibilities towards a wide variety of emerging ...biological and biomedical applications. By taking the advantages of the microdroplet anchoring ability, enrichment ability, and the accessibility of such bioinspired micropatterns, the selected topic mainly focuses on the important aspects related to (super)wettable surfaces and their emerging sensing applications (DNA, miRNA, proteins, etc.) by combining them with multiple signal output approaches (fluorescence, colorimetric, SERS, electrochemical, etc.). In the end, we also provide a personal perspective on the future development, and address the remaining challenges in the commercialization of (super)wettable micropatterns towards biosensing.
A nanodendritic gold/graphene-based biosensor that can perform fluorescence, SERS and electrochemical tri-modal miRNA detection in a single microdroplet has been developed. The biosensor was used to ...successfully perform tri-modal quantitative trace miRNA-375 detection, which enormously reduces false positive readings caused by interference and ambiguous signals, and has significant implications for use in precise physiological and pathological diagnosis.
By combining a superwettable interface with a nanodendritic gold structure, we have fabricated a superwettable nanodendritic gold substrate for direct SERS detection of multiple concentrations of ...miRNAs. The nanodendritic gold substrate provides numerous hotspots for Raman signal enhancement, and the superwettable interface ensures the immobilization of droplets in superhydrophilic microwells, which hold great potentials for applications in disease diagnostics.
Large‐area dual‐scaled porous nitrocellulose (p‐NC) membranes are fabricated by a facile, inexpensive and scalable perforating approach. These p‐NC membranes show stable superhydrophilicity in air ...and underwater superoleophobicity. The p‐NC membranes with intrinsic nanopores and array of microscale perforated pores could selectively and efficiently separate water from various oil/water mixtures with high efficiency (> 99%) rapidly.
A sensitive nucleic acid detection platform based on superhydrophilic microwells spotted on a superhydrophobic substrate is fabricated. Due to the wettability differences, ultratrace DNA molecules ...are enriched and the fluorescent signals are amplified to allow more sensitive detection. The biosensing interface based on superwettable materials provides a simple and cost‐effective way for ultratrace DNA sensing.
Three-dimensional (3D) DNA walking machines inspired by natural molecular machines have attracted significant attention due to their high walking efficiency and signal amplification capability. ...Herein, we report a 3D DNA walking machine for the dual-modal detection of miRNA using a fluorometer and personal glucose meter (PGM). The 3D DNA walking machine on magnetic beads (MBs) was coated with the BHQ-H1-FAM hairpin structures (DNA tracks), activated by target miRNA-21 (walking strand) and propelled by a strand displacement reaction. During these processes, the fluorescence of FAM on H1 was turned on (first signal), and the invertase on H2 was introduced into the surface of the MBs. After being separated by an external magnetic field, the invertase hydrolyzed sucrose into glucose to generate a second signal, which was quantified by the PGM. The developed 3D DNA walking machine showed high sensitivity and good specificity, and the detection limits of 98 pM and 60 pM were obtained for the fluorescence-based assay and PGM-based assay, respectively. Compared with the single-modal detection, the developed DNA walking machine can achieve a unique double signal readout and more reliable sensitive performance. In addition, the proposed 3D DNA walking machine was successfully applied to detect miRNA in real biological samples. The 3D DNA walking machine with dual-modal detection has potential applications in disease diagnostics and clinical applications and can satisfy different testing requirements both in the laboratory and field.
Transition metal-catalyzed C-H bond oxidation of free carboxylic acid stands as an economic, selective, and efficient strategy to generate lactones, hydroxylated products, and acetoxylated products ...and attracts much of the chemists' attention. Herein, we performed a density functional theory study on the mechanism and selectivity in Pd-catalyzed and MPAA ligand-enabled C-H bond acetoxylation reaction. It was found that the ligand, base, and substrate are important in determining the reaction mechanism and the selectivity. The acetic anhydride additive is critical in leading the reaction to be acetoxylation, instead of the lactonization, through a facile σ-bond metathesis mechanism that leads to the Pd-OAc in-termediate. Our study sheds light on the further development of transition metal-catalyzed C-H bond oxidation reactions.
Here, we report the first example of Ni‐catalyzed asymmetric hydrosilylation of 1,1‐disubstituted allenes with high level of regioselectivities and enantioselectivities. The key to achieve this ...stereoselective hydrosilylation reaction was the development of the SPSiOL‐derived bisphosphite ligands (SPSiPO). This protocol features broad substrate scope, excellent functional group, and heterocycle tolerance, thus provides a versatile method for the construction of enantioenriched tertiary allylsilanes in a straightforward and atom‐economic manner. DFT calculations were performed to reveal the reaction mechanism and the origins of the enantioselectivity.
With a newly developed SPSiOL‐base bisphosphite ligand (SPSiPO), Ni‐catalyzed asymmetric hydrosilylation of 1,1‐disubstituted allenes was realized for the first time, delivering the enantioenriched allylsilanes bearing a tertiary carbon stereocenter in high efficiency and 100 % atom‐economy with high chemo‐, regio‐ and enantioselectivities.
Staphylococcus aureus is one of the most important food-borne bacterial pathogens and causes numerous illnesses. In this work, we report a sensitive and highly selective magnetic-aptamer biosensor ...based on a personal glucose meter (PGM) platform for the detection of Staphylococcus aureus. The aptamer for Staphylococcus aureus was immobilized on the magnetic bead by hybridization with the capture probe P. In the presence of Staphylococcus aureus, the aptamer was dissociated from the magnetic bead. Then the capture probe was exposed and could be hybridized with a biotinylated probe to trigger the DNA hybridization chain reaction (HCR), thus achieving the signal amplification. The concentration of streptavidin-labeled invertase can be read by PGM, thus can lead to the portable quantitative detection of Staphylococcus aureus. After optimization of various conditions, 5 μM probe P, the MB-P reaction time for 36 h, the competition time for 60 min, 0.5 μM H1 & H2, 0.5 M sucrose and the sucrose invertase catalytic reaction time for 50 min was chosen to achieve the better sensor performance. Under the optimal conditions, the fabricated sensor offers high sensitivity with the limit of detection about 2 CFU/mL. This sensitive PGM based sensor could successfully evaluate the Staphylococcus aureus concentration in real food samples, and the results are consistent with those obtained by using plate counting methods. Moreover, the PGM sensor can greatly reduce the required time compared to the plate counting methods. The fabricated sensor supplies an ideal solution for rapid portable detection of bacterial pathogens and holds its potential use in the quality control for agriculture and food enterprises, entry-exit inspection and quality testing for food.
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•A portable detection method using personal glucose meter (PGM) for the detection of Staphylococcus aureus was proposed.•Realized the great sensitivity toward Staphylococcus aureus detection by hybridization chain reaction strategy (HCR).•The Staphylococcus aureus detection with the limit of detection about 2 CFU/mL.•A highly sensitivity and high specificity were observed.•This sensing strategy exhibited an excellent platform for portable detection of bacterial pathogens in real food samples.
