In this work, we demonstrate a strategy to control the accumulation of water in the oil–solid interface using a gradient coating. Gradient chemistry on glass surface is created by vapor diffusion of organosilanes, leading to a range of contact angles from 110 to 20°. Hexadecane is placed on the gradient substrate as an oil layer, forming a “water/hexadecane/gradient solid substrate” sandwich structure. During incubation, water molecules spontaneously migrate through the micrometer-thick oil layer and result in the formation of micrometer-sized water droplets at the oil–solid interface. It turns out that water droplets at more hydrophobic regions tend to be closer to a regular spherical shape, which is attributed to their higher contact angle with the hydrophobic substrate. However, along the gradient from hydrophobic to hydrophilic, the water droplets gradually form more irregular shapes, as hydrophilic surfaces pin the edges of droplets to form a distorted morphology. It indicates that more hydrophilic surfaces containing more Si–OH groups lead to a higher electrostatic interaction with water and a higher growth rate of interfacial water droplets. This work provides further insights into the mechanism of spontaneous water accumulation at oil–solid interfaces and assists in the rational design for controlling such interfacial phenomenon.

DNA hydrogel has aroused widespread attention because of its unique properties. In this work, the DNA-modified magnetic nanoparticles were integrated into the mainframe of DNA hydrogel, resulting in DNA-MNP hydrogel. Under the magnetic field, this hydrogel can be remotely deformed into various shapes, driven to jump between two planes and even climb the hill. By applying various triggers, such as temperature, enzyme, and magnetic field, DNA-MNP hydrogel can specifically undergo sol–gel transition. This work not only imparts DNA hydrogel with a new fold of property but also opens a unique platform of such smart materials for its further applications.Keywords: DNA conjugation; DNA hydrogel; hydrogel movement; magnetic nanoparticle; remote controlling;

This study demonstrates a new process for preparation of oil-in-water (O/W) emulsion using the high gravity technique. This involves a mixture of oil and water that are passed through a rotating packed bed, under a high shear force, from which oil is emulsified into tiny droplets and subsequently dispersed in water. The process is cycled in order to break the droplets repeatedly and achieve an emulsion with small size and low polydispersity index (PDI). The advantage of the high gravity technique is that the emulsions with a desired size and polydispersity can be rapidly obtained by tuning experimental parameters, such as relative centrifugal force (RCF), cycle times (CT), liquid flow rate (VL) and surfactant concentration (Csurfactant). The size of emulsions is shown to decrease with increasing RCF, CT, VL and Csurfactant. The PDI of emulsion prepared by high gravity technique is also much improved in comparison to that prepared by conventional sonication, which is further confirmed with dynamic light scattering and confocal imaging characterization. To provide an additional perspective on the high gravity technique as a tool to make O/W emulsions, uniformly distributed liquid crystal droplets were prepared by using the high gravity technique, which have been well studied for their in situ chemical and biological detection. In short, the high gravity technique for preparing emulsions is facile, fast and can be potentially applied for large scale industry applications.Download high-res image (162KB)Download full-size image

DNA modified nanoparticles (AuNPs) are an established and widely used type of nucleotide sensor. We sought to improve the design by applying short rigid DNA duplexes near the surface of the AuNPs forming a so called double-anchored AuNP sensor, and compared it with other conventional DNA modified AuNPs. The improved design exhibited higher assembly efficiency, and consequently increased its sensitivity to target DNA.

This work offers a methodology for screening compatible buffer conditions for both DNA origami and protein crystallisation and studied how protein crystallisation buffer conditions notably cations, buffering agents, precipitants, and pH, influenced the stability of tubular DNA origami.

Liquid crystals (LCs) are often known as electronic displays and have become ubiquitous in our daily life, apart from that, in the past 10 years, LCs have been investigated as exquisitely sensitive reporters for developing new molecular sensing and detection tools. The unique and primary advantage of this class of intriguing materials is the perturbation of the local ordering LCs at molecular scale by bio/chemical species can be communicated within LC molecules and extended over microns, allowing the observation of the optical signals by microscope or even the naked eye. Therefore, it provides a new platform for developing bio/chemical detection and potentially label-free sensing systems.

We report a general approach to bimodify gold nanoparticles (GNPs) with two different DNA strands via DNA template reaction. Two thioctic acid modified DNA strands, one at 5′ end and one at 3′ end, were attached to GNPs through bivalent thiol-gold bond. By sequence design, assemblies of 5 nm GNPs chains, 10 nm GNPs chains and alternative arrangement of 5 and 10 nm GNPs could be achieved. Gel electrophoresis, transmission electron microscope (TEM), UV–vis spectra were used to characterize the assemblies. It is believed that this new kind of bimodified GNPs with two different DNA strands at different ends would enrich the toolbox of DNA–GNP conjugates and provide diverse selectivity for further assembly.

In this research, we employed tetra(ethylene glycol) (EG4) to substitute bases at the loop region of the intramolecular DNA i-motif formed by (CCCTAA)3CCC, and systematically studied the influence of such nonbase components on the stability and conformation of the formed structures by circular dichroism (CD), UV–vis spectroscopy and gel electrophoresis. We found that with all loop bases substituted, the i-motif structure can still form. The stability of the i-motif generally got weaker with the increase of the substitution number. Substitution at different positions might lead to different topologies. The findings above demonstrate that bases at the loop region play an important role on the stability and topology of the intramolecular DNA i-motif.

•Methods for covalent terminal functionalization of DNA are introduced, mainly on the technical aspect.•The basic principle and important factors of reaction conditions for each method are described and discussed.•Further applications of these functionalized DNA are also introduced.The functionalized DNA has been widely developed and played a more and more important role in life science and material science during last decades. Therefore, methods to effectively endue DNA new functions by modifying DNA have been developed quickly. In this review, we will give an introduction in the methods for covalent terminal functionalization of DNA, including solid-phase functionalization and solution coupling functionalization, mainly on the technical aspect. The application of these functionalized DNA will be also introduced.Download high-res image (70KB)Download full-size image