Search

The analysis and detection of ultra-trace biomarkers are often carried out in microliter droplets. Common stirring approaches have some difficulties in precise and contactless mixing and dispersion in microdroplets. In this work, an open mini-pillar-based platform that integrates with ultrasound units is developed to achieve contactless mixing and dispersion in microliter samples. On such a platform, mini-pillars can anchor microdroplets as individual microreactors, and each ultrasound unit can be remotely controlled to achieve on-demand contactless micro-stirring, which is also confirmed by mixing and dispersing of Fe3O4 nanoparticles (1 μm) in microdroplets (10 μL). Such on-demand high-throughput mixing and dispersion that integrates ultrasound mixing with microdroplet technology provides a potential robot-based platform for achieving high-throughput and ultra-trace biosensing in microliter droplets.

Inspired by natural ciliary movement, artificial cilia systems have recently been developed to transport microparticles and target biomolecules by the external stimuli-induced bend and twist. However, the directional transportation of cargo meets a major challenge. Here, we present an artificial asymmetric cilia array of dielectric elastomer and realize the cargo directional transportation under alternating-current (ac) electric field. Such a dielectric elastomer is composed of elastomer matrix and dielectric barium titanate (BaTiO 3 ) nanoparticles, which can be polarized under an ac electric field and results in the swinging of artificial elastomer cilia. The asymmetry of the cilia endows themselves with the capability of asymmetric recovery stroke, which is essential for directional transportation of cargo. Transporting performance is also optimized by adjusting the applied frequencies and voltages. This study may provide a new clue to construct functional "smart" devices in electromechanical systems and biomedicine.

To achieve an excellent delivery effect of drug, stimuli-responsive nano "gate" with physical blockage units is usually constructed on the surface of the mesoporous silica nanocarriers (MSNs). In nature, the aquaporins in cell membrane can control the transport of water molecules by regulating the channel wettability, which is resulted from the conformational change of amino acids in the channel. Inspired by this phonomenon, herein a new concept of free-blockage controlled release system is proposed, which is achieved by controlling the wettability of the internal surface of nanopores on MSNs. Such a new system is different from the physical-blockage controlled release system, which bypasses the use of nano "gate" and overcomes the limitations of traditional physical blockage system. Moreover, further studies have shown that the system can selectively release the entrapped doxorubicin in human breast adenocarcinoma (MCF-7) cells triggered by intracellular reactive oxygen species (ROS) but not in normalhuman umbilical vein endothelial cells (HUVECs) containing ROS with low levels. The wettability-determined free-blockage controlled release system is simple and effective, and it can also be triggered by intracellular biological stimuli, which provides a new approach for the future practical application of drug delivery and cancer therapy., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Directional transportation as is a common phenomenon in nature, has significant potential in advanced devices and technology. Most of the studies focus on the directional transport of water on an anisotropic surface with gradients in Laplace pressure. However, rare attentions are paid to on‐demand transportation of macroscale object on static microscale anisotropic structure. Herein, bioinspired by the phenomenon that the breath air promotes the mucus gel transport in trachea, a transport system by combining static microcilia with anisotropic structure, water layer, and air‐blowing device, realizing directional transport of macroscale object under air flow is fabricated. Owing to the anisotropic friction, the anisotropic microcilia arrays achieve transporting centi‐scale hydrogel slice when air flow along their tilted direction. In contrast, air flow against their tilted direction results in hard transport. By introducing cobalt nanoparticles into microcilia, the transport direction can also be easy tuned by regulating the magnetic field. This contribution should expand more properties and functions of anisotropic surface, and provides a clue to design the next generation of micro‐electromechanical systems. [ABSTRACT FROM AUTHOR]

We report core@satellite Janus mesoporous silica‐Pt@Au (JMPA) nanomotors with pH‐responsive multi‐phoretic propulsion. The JMPA nanomotors first undergo self‐diffusiophoretic propulsion in 3.0 % H2O2 due to the isolation of the Au nanoparticles (AuNPs) from the PtNPs layer. Then the weak acidity of H2O2 can trigger the disassembly and reassembly of the AuNPs, resulting in the Janus distribution of large AuNPs aggregates. Such reconstruction of JMPA leads to the contact between PtNPs and AuNPs aggregates, thus changing the propulsion mechanism to self‐electrophoresis. The asymmetric and aggregated AuNPs also enable the generation of a thermal gradient under laser irradiation, which propels the JMPA nanomotors by self‐thermophoresis. Such multi‐phoretic propulsion offers considerable promise for developing advanced nanomachines with a stimuli‐responsive switch of propulsion modes in biomedical applications. [ABSTRACT FROM AUTHOR]

This review (with 187 refs.) summarizes the progress that has been made in the design of lateral flow biosensors (LFBs) based on the use of micro- and nano-materials. Following a short introduction into the field, a first section covers features related to the design of LFBs, with subsections on strip-based, cotton thread-based and vertical flow- and syringe-based LFBs. The next chapter summarizes methods for sample pretreatment, from simple method to membrane-based methods, pretreatment by magnetic methods to device-integrated sample preparation. Advances in flow control are treated next, with subsections on cross-flow strategies, delayed and controlled release and various other strategies. Detection conditionst and mathematical modelling are briefly introduced in the following chapter. A further chapter covers methods for reliability improvement, for example by adding other validation lines or adopting different detection methods. Signal readouts are summarized next, with subsections on color-based, luminescent, smartphone-based and SERS-based methods. A concluding section summarizes the current status and addresses challenges in future perspectives. [ABSTRACT FROM AUTHOR]

The assembly of micro‐nanoparticles is one of the key tasks for controlling and manipulating the structure of materials at micro/‐nanoscale. By carefully designing the ultrasound experiments and comparing the results with acoustic theories, we presented an in‐depth study of the ultrasound‐induced assembly behaviors of micro/‐nanoparticles (microparticle size≪wavelength), especially their dynamic interactions between microparticles. The whole assembly processes including floating micro/nanoparticles, single particle communication, assembly to single particle interactions, and reorganization of assembly are fully studied. A rapid response of the ultrasound‐based assembly (0.5 min) shows distinct advantages compared to those of previously used methods such as light‐, electrical‐ and temperature‐based ones. Such an efficient and effective microparticle assembly holds great promise for fabrication of complex structure of materials. [ABSTRACT FROM AUTHOR]

Amyloid-β oligomer is an important biomarker and a potential therapeutic target of Alzheimer's disease in its early stage. Here, we combined superhydrophobic carbon fiber paper (CFP) with AuPt alloy nanoparticles to prepare a CFP/AuPt nanocomposite with larger specific surface area and hydrophobic surface. On this basis, we constructed an electrochemical aptasensor based on CFP/AuPt for the ultrasensitive detection of amyloid-β oligomers. The surface-coated AuPt nanoparticles greatly enhanced the electroactive area, and the hydrophobic surface increased the resisting nonspecific adsorption performance of sensor. A combination of these two features significantly improved the sensitivity and specificity of the sensor. This electrochemical aptasensor based on CFP/AuPt displayed a low detection limit of 0.16 pg/mL. This work shows a promising future in clinical diagnosis of Alzheimer's disease and provides a possible solution to electrochemical biosensors that are susceptible to interference in biological fluids. [Display omitted] • An electrochemical aptasensor based on CFP/AuPt nanocomposites was designed for AβO detection. • This electrochemical aptasensor exhibited high sensitivity, good specificity, and low detection limit. • This aptasensor displayed excellent resisting protein adsorption performance in serum. [ABSTRACT FROM AUTHOR]