Apoferritin caged gold nanoparticles (AuNPs) were assembled into flower-like structures by precise base pairing of the attached DNA molecules. The key step was to use the eight hydrophilic channels through the apoferritin to control the exact number and locations of the DNA molecules that grafted onto the caged AuNP.

Siloxane @ poly (methylacrylic acid) core-shell microparticles with functional groups were prepared by a facile hydrolysis-condensation method in this work. Three different silane coupling agents 3-methacryloxypropyltrimethoxysilane (MPS), 3-triethoxysilylpropylamine (APTES), and 3-glycidoxypropyltrimethoxysilane (GPTMS) were added along with tetraethoxysilane (TEOS) into the polymethylacrylic acid (PMAA) microparticle ethanol dispersion to form the Si@PMAA core-shell microparticles with different functional groups. The core-shell structure and the surface special functional groups of the resulting microparticles were measured by transmission electron microscopy and FTIR. The sizes of these core-shell microparticles were about 350–400 nm. The corresponding preparation conditions and mechanism were discussed in detail. This hydrolysis-condensation method also could be used to functionalize other microparticles which contain active groups on the surface. Meanwhile, the Si@PMAA core-shell microparticles with carbon-carbon double bonds and amino groups have further been applied to prepare hydrophobic coatings.

The vulcanizers, sulfur (S) together with benzoyl peroxide (BPO), tetramethylthiuram monosulfide (TMTM) or tetramethylthiuram disulfide (TMTD) were added to isotactic polypropylene (iPP) during reactive extrusion process. The goal of this work is to investigate the influence of vulcanizers on the crystallization property of iPP. After addition of vulcanizers, iPP samples showed faster flow property, which indicated a low molecular weight formed during thermal degradable process. Moreover, a small characteristic peak at about 700 cm−1 was appeared, which indicated that some local cross-linking structure was formed by CS bond as investigated by FTIR. The results of non-isothermal crystallization dynamics showed that the addition could improve the crystallization temperature of 2–5 °C, and shortened the half time of crystallization from 0.97 to 0.92 min. Wide angle X-ray diffraction demonstrated that the addition contributed to form local cross-linking structure as a foreign phase to thick the (130) crystal plane of α-crystal lamellar from 19.1 nm to 21.4 nm and to evidently form γ-crystal of iPP greater than 30% within crystal phase. The data calculated from differential scanning calorimetry melting patterns also confirmed that modified iPP shows larger crystal size than pure samples.

DNA polyhedron-caged gold nanoparticles (AuNP) were self-assembled using four-point-star DNAs, with three strands hybridizing to each other and the fourth strand attaching to the AuNPs. The DNA-caged AuNPs can work as nanocarriers for doxorubicin, and controlled release behaviour can be triggered by both a DNA enzyme and by the pH value.

DNA was covalently grafted onto poly(propargyl methacrylate) (PPMA) via “click” chemistry to synthesize the amphiphilic polymer brush. The PPMA-g-DNA brush could assemble into a primary structure of a nanofiber, which can be compactly spun into a multiple-strand helix in micron-length. The brush could also self-assemble with DNA labelled gold nanoparticles.

Encapsulation technology has important applications in drug delivery, catalysis, sensing and photonics. In this paper, a stretchable and tough hollow capsule was synthesized using alginate and polyacrylamide (PAAm) as the shell material. Calcium carbonate (CaCO3) microspheres were first chosen as sacrificial templates for the covalent crosslinking of the PAAm network at their surface. Then, they were decomposed using acid to form a hollow capsule, and the released Ca2+ ions were used for the ionic crosslinking of the alginate network. The influence of the density of CaCO3 microspheres on the internal structure of the capsules was explored and the ball loading ball structure was observed by scanning electron microscopy and fluorescence microscopy. The mechanical strength of the prepared capsules was studied by both tensile/compressive testing and an osmotic pressure method, and the results showed that the volume of capsules could be expanded at least 27 times their original sizes without breakage. The release behaviours of the model drug BSA-FITC for three capsules with different crosslinking densities were studied, and the results showed that drug loading capacity and water absorption ratio were proportional to the number of CaCO3 microspheres used during the preparation.

Three series of multicomponent silicone hydrogels were prepared by the copolymerization of two hydrophobic silicon monomers bis(trimethylsilyloxy) methylsilylpropyl glycerol methacrylate (SiMA) and tris(trimethylsiloxy) 3-methacryloxypropylsilane (TRIS) with three hydrophilic monomers. The surface hydrophilicity of the silicone hydrogels was characterized by contact angle measurements, and an interesting phenomenon was found that the silicone hydrogels made from less hydrophobic monomer SiMA possess more hydrophobic surfaces than those made from TRIS. The surface properties such as morphology and elemental composition of the silicone hydrogels were explored by scanning electron microscopy (SEM) imaging and energy dispersive spectrometry (EDS) analysis, and their relationships with the surface hydrophilicity were investigated in details. The results show neither the surface morphology nor the elemental composition has obvious impact on the surface hydrophilicity. Atomic force microscopy (AFM) imaging revealed that SiMA hydrogel had a more significant phase separation structure, which also made its surface uneven: a lot of tiny holes were observed on the surface. This surface phase separation structure made SiMA hydrogel more difficult to be wetted by water or PBS buffer, i.e., more hydrophobic than TRIS hydrogel. On the basis of these results, we propose that the phase separation structure as well as the nature of silicon monomers might be the fundamental reasons of surface hydrophilicity. These results could help to design a silicone hydrogel with better surface properties and wider application.

A series of multicomponent hydrogels were prepared by the copolymerization of hydrophobic silicon-containing monomer 3-bis(trimethylsilyloxy) methylsilylpropyl glycerol methacrylate (SiMA) with the solvent-responsive monomers 2-hydroxyethyl methacrylate (HEMA) and N-vinyl pyrrolidone (NVP) and thermosensitive monomer N,N-dimethyl acrylamide (DMA). 2-Hydroxy-2-methyl phenyl acetone (D-1173) was chosen as UV initiator and five different dienes/triene monomers were selected as crosslinking agent in order to select the best crosslinker. The ethanol extraction experiments as well as the FTIR, DSC and TG results showed that the copolymerization was effective. The optical, permeability, and mechanical analysis results demonstrated that the obtained hydrogels were highly transparent with good oxygen permeability and mechanical properties. And the impact of crosslinker on the mechanical properties of the hydrogels was also discussed in detail. The basic results demonstrated that the obtained hydrogels had good stimuli-responsive effects to both pH value and solvent.

In this paper, a DNA–PEI microcapsule with novel nuclease-responsive controlled release properties was demonstrated. This microcapsule was constructed by the self-assembly of native DNA and PEI, and can work as a dual carrier for both DNA in the capsule shell and drugs inside the capsule. The controlled release behavior of the model drug BSA–FITC was studied using fluorescence microscopy and UV spectroscopy, and the results show that the synergetic controlled release can be triggered very well by a bio-stimulus, DNA nuclease recognition capsule decomposition, as well as the pH value and salt concentration. The therapeutic effects of the drug are enhanced due to the bio-stimuli responsive properties and the synergetic release of DNA and the drug together.

Multiple nanomaterials were assembled on a circular DNA to form a necklace. AuNPs were first attached to natural PhiX174 ss-DNA, and then a single-circle PCR was adopted to immobilize the attachments. The structures of the assemblies were confirmed by TEM imaging and UV-vis spectrometry. In this way, various types and shapes of nanomaterials were assembled on the DNA, such as palladium nanocubes and gold nanorods.

In this article, the multicomponent copolymers were prepared by the copolymerization of two hydrophobic silicon-containing monomers bis(trimethylsilyloxy) methylsilylpropyl glycerol methacrylate (SiMA) and tris(trimethylsiloxy)-3-methacryloxypropylsilane (TRIS) with three hydrophilic monomers 2-hydroxyethyl methacrylate, N-vinylpyrrolidone, and N,N-dimethyl acrylamide. The copolymers were hydrated to form transparent silicone hydrogels. The oxygen permeability coefficients (Dk) of hydrogels were measured, and their relationships with the equilibrium water contents (EWC) and the types and contents of silicon containing monomers as well as the phase separation structures of silicone hydrogels were analyzed in detail. The results showed that the EWC decreased as the increase of SiMA content. The relationship between Dk and SiMA content, as well as that between Dk and EWC, showed inverted bell curve distributions, which meant two main factors, i.e., silicon–oxygen bond in silicone and water in hydrogel, contributed to oxygen permeation and followed a mutual inhibition competition mechanism. The internal morphologies of the hydrogels were observed by transmission electron microscope, and the results showed that the hydrogels presented two different phase separation structures depending on the types of the silicon-containing monomers. The silicone phase in SiMA containing hydrogel presented to be a granular texture, while the silicone phase in TRIS containing hydrogel formed a fibrous texture which resulted in a higher Dk value. These results could help to design a silicone hydrogel with better properties and wider application.

Atomic force microscopy (AFM), which provides true 3D surface topography, can also be used to determine the geometric parameters of proteins quantitatively at a single molecular level. In this paper, two different kinds of Escherichia coli MutS (MutS) protein were observed using AFM, and the geometric parameters of the proteins such as height, perimeter, area, and volume were measured. On the basis of these measurements, the molecular weight, association constant, oligomeric state, and orientation of MutS proteins on a mica surface were deduced. The oligomerization mechanism of MutS was analyzed in detail, and the results show that two different kinds of interactions between MutS protein may be involved in oligomerization. Our results also show that AFM imaging is an accurate method for analyzing the geometric structures of a single protein quantitatively at a single-molecule level.

In this paper, nano-TiO2 was functionalized by different methods, and its genotoxicity and cytotoxicity were studied in detail. The genotoxicity of nano-TiO2 was evaluated by observing its interactions with pUC19 plasmid DNA at a single molecule level using atomic force microscopy. The results show that with the assistance of UVA radiation, RGDC functionalized nano-TiO2 induced less damage to plasmid DNA than unmodified ones. The HeLa cell-specific PDT effect was investigated by cytotoxicity assay correspondingly. RGDC-functionalized nano-TiO2 shows the highest killing effect to HeLa cells with the assistance of UVA radiation. The reasons that cause the contradiction between genotoxicity and cytotoxicity were analyzed, and the molecular mechanisms of the PDT effects were discussed. The results show that the genotoxicity of nano-TiO2 to plasmid DNA and its cytotoxicity to HeLa cells are related but also different. The RGDC functionalization is an effective method to increase the cytotoxicity of nano-TiO2.

Failure analysis (FA) at nanometer or micrometer scale on integrated circuit (IC) becomes progressively more challenging as the complexity of new IC devices increases and their sizes decrease. In this paper, conductive atomic force microscopy (CAFM) was employed as an alternative technique for single-bit failure analysis. Using CAFM current imaging, one can screen out each failure bit and locate its position quickly and simply by applying suitable bias during CAFM scanning. Furthermore, using CAFM current–voltage (I–V) measurements, one can acquire the full electrical characteristic of each failure bit, which is very useful to determine the associated mechanism of the physical defect. The results show that CAFM current imaging together with the I–V measurement can be a suitable candidate for FA at the single-bit level.Highlights► Conductive atomic force microscopy (CAFM) is an alternative for failure analysis. ► Each failure bit can be analyzed quickly and simply at a single-bit level. ► The position of each failure bit can be located by CAFM imaging. ► The electrical characteristic can be acquired by CAFM current–voltage measurements.

Atomic force microscopy, which is normally used for DNA imaging to gain qualitative results, can also be used for quantitative DNA research, at a single-molecular level. Here, we evaluate the performance of AFM imaging specifically for quantifying supercoiled and relaxed plasmid DNA fractions within a mixture, and compare the results with the bulk material analysis method, gel electrophoresis. The advantages and shortcomings of both methods are discussed in detail. Gel electrophoresis is a quick and well-established quantification method. However, it requires a large amount of DNA, and needs to be carefully calibrated for even slightly different experimental conditions for accurate quantification. AFM imaging is accurate, in that single DNA molecules in different conformations can be seen and counted. When used carefully with necessary correction, both methods provide consistent results. Thus, AFM imaging can be used for DNA quantification, as an alternative to gel electrophoresis.

In this paper, a DNA–PEI microcapsule with novel nuclease-responsive controlled release properties was demonstrated. This microcapsule was constructed by the self-assembly of native DNA and PEI, and can work as a dual carrier for both DNA in the capsule shell and drugs inside the capsule. The controlled release behavior of the model drug BSA–FITC was studied using fluorescence microscopy and UV spectroscopy, and the results show that the synergetic controlled release can be triggered very well by a bio-stimulus, DNA nuclease recognition capsule decomposition, as well as the pH value and salt concentration. The therapeutic effects of the drug are enhanced due to the bio-stimuli responsive properties and the synergetic release of DNA and the drug together.

Apoferritin caged gold nanoparticles (AuNPs) were assembled into flower-like structures by precise base pairing of the attached DNA molecules. The key step was to use the eight hydrophilic channels through the apoferritin to control the exact number and locations of the DNA molecules that grafted onto the caged AuNP.

DNA polyhedron-caged gold nanoparticles (AuNP) were self-assembled using four-point-star DNAs, with three strands hybridizing to each other and the fourth strand attaching to the AuNPs. The DNA-caged AuNPs can work as nanocarriers for doxorubicin, and controlled release behaviour can be triggered by both a DNA enzyme and by the pH value.