Three‐Dimensional Nanofabrication by Block Copolymer Self‐Assembly

Thin films of block copolymers are widely seen as enablers for nanoscale fabrication of semiconductor devices, membranes, and other structures, taking advantage of microphase separation to produce well‐organized nanostructures with periods of a few nm and above. However, the inherently three‐dimensional structure of block copolymer microdomains could enable them to make 3D devices and structures directly, which could lead to efficient fabrication of complex heterogeneous structures. This article reviews recent progress in developing 3D nanofabrication processes based on block copolymers.     

Effect of Pd thickness on wettability and interfacial reaction of Sn-1.0Ag-Ce solders on ENEPIG surface finish

The wetting balance test was used to study the wettability of Sn-1.0Ag-Ce (Ce content = 0, 0.1, 0.3, and 0.5 wt%) solder alloys on electroless nickel/electroless palladium/immersion gold (ENEPIG) surface finishes with Pd thicknesses of 0, 0.05, 0.1, and 0.15 μm. Scanning electron microscopy was used to evaluate the interfacial reaction between the molten solders and surface finish materials during the wetting test. The Ni₃Sn₄ intermetallic compound (IMC) plays an important role in promoting wetting properties. The Pd layer retards formation of the Ni₃Sn₄ IMC and changes its morphology, thereby affecting the wettability of the surface finish/solder systems. ENEPIG surface finishes seem to be suitable for use with cerium-containing solders.     

Microbial Synthesis of Medium‐Chain α,ω‐Dicarboxylic Acids and ω‐Aminocarboxylic Acids from Renewable Long‐Chain Fatty Acids

Biotransformation of long‐chain fatty acids into medium‐chain α,ω‐dicarboxylic acids or ω‐aminocarboxylic acids could be achieved with biocatalysts. This study presents the production of α,ω‐dicarboxylic acids (e.g., C₉, C₁₁, C₁₂, C₁₃) and ω‐aminocarboxylic acids (e.g., C₁₁, C₁₂, C₁₃) directly from fatty acids (e.g., oleic acid, ricinoleic acid, lesquerolic acid) using recombinant Escherichia coli‐based biocatalysts. ω‐Hydroxycarboxylic acids, which were produced from oxidative cleavage of fatty acids via enzymatic reactions involving a fatty acid double bond hydratase, an alcohol dehydrogenase, a Baeyer–Villiger monooxygenase and an esterase, were then oxidized to α,ω‐dicarboxylic acids by alcohol dehydrogenase (ADH, AlkJ) from Pseudomonas putida GPo1 or converted into ω‐aminocarboxylic acids by a serial combination of ADH from P. putida GPo1 and an ω‐transaminase of Silicibacter pomeroyi. The double bonds present in the fatty acids such as ricinoleic acid and lesquerolic acid were reduced by E. coli‐native enzymes during the biotransformations. This study demonstrates that the industrially relevant building blocks (C₉ to C₁₃ saturated α,ω‐dicarboxylic acids and ω‐aminocarboxylic acids) can be produced from renewable fatty acids using biocatalysis.

     

Fabrication of periodically aligned vertical single-crystalline anatase TiO2 nanotubes with perfect hexagonal open-ends using chemical capping materials

A vertically aligned anatase TiO2 （A-TiO2） nanotube array has been fabricated by coating a ZnO nanorod （NR） template with a TiO2 precursor solution. After coating, the ZnO NR cores were selectively etched in an acidic environment to form TiO2 nanotubes （NTs）. More specifically, after growing the ZnO NRs via a hydrothermal method, one drop of the TiO2 precursor solution was cast to coat the ZnO NRs, the tops of which were previously covered with chemical capping materials by electrostatic interaction, and then the sample was sintered. Finally, the sample was immersed in an acidic solution resulting in selective etching of the ZnO NR cores. Thus, only TiO2 NTs remained on the substrate. The capping material is effectively used to create a perfect, hexagonal open-ended TiO2 NT array, which interestingly extends onset absorption towards the visible region.     

Two‐Dimensional Periodic Relief Gratings as a Versatile Platform for Label‐Free Specific DNA Detection

In this study, nanopillar arrays of silicon oxide are fabricated through a process involving very‐large‐scale integration, for use as two‐dimensional periodic relief gratings (2DPRGs) on silicon surfaces. Oligonucleotides are successively immobilized on the pillar surface, allowing the system to be used as an optical detector specific for the targeted single‐stranded DNAs (ssDNAs). The surfaces of the oligonucleotides‐modified 2DPRGs undergo insignificant structural changes, but upon hybridizing with target ssDNA, the 2DPRGs undergo dramatic changes in terms of their pillar scale. Binding of the oligonucleotides to the 2DPRG occurs in a way that allows them to retain their function and selectively bind the target ssDNA. The performance of the sensor is evaluated by capturing the target ssDNA on the 2DPRGs and measuring the effective refractive index (n_eff). The binding of the target ssDNA species to the 2DPRGs results in a color change from pure blue to red, observable by the naked eye along an angle of 15–20°. Moreover, effective medium theory is used to calculate the filling factors inside the 2DPRGs and, thereby, examine the values of n_eff during the structural changes of the 2DPRGs. Accordingly, these new films have potential applications as label‐free optical biosensors.     

A Multifunctional Nanoplatform for Imaging,Radiotherapy, and the Prediction of Therapeutic Response

Gold nanoparticles have garnered interest as both radiosensitzers and computed tomography (CT) contrast agents. However, the extremely high concentrations of gold required to generate CT contrast is far beyond that needed for meaningful radiosensitization, which limits their use as combined therapeutic–diagnostic (theranostic) agents. To establish a theranostic nanoplatform with well‐aligned radiotherapeutic and diagnostic properties for better integration into standard radiation therapy practice, a gold‐ and superparamagnetic iron oxide nanoparticle (SPION)‐loaded micelle (GSM) is developed. Intravenous injection of GSMs into tumor‐bearing mice led to selective tumoral accumulation, enabling magnetic resonance (MR) imaging of tumor margins. Subsequent irradiation leads to a 90‐day survival of 71% in GSM‐treated mice, compared with 25% for irradiation‐only mice. Furthermore, measurements of the GSM‐enhanced MR contrast are highly predictive of tumor response. Therefore, GSMs may not only guide and enhance the efficacy of radiation therapy, but may allow patients to be managed more effectively.     

A smartphone‐based U‐Healthcare system for real‐time monitoring of acute myocardial infarction

In recent years, medical service has been evolving from systems designed around centralized hospitals to Ubiquitous Healthcare (U‐Healthcare). U‐Healthcare system can facilitate real‐time monitoring of patient states, and can provide medical checkups and management whenever and wherever the medical staff deems necessary. U‐Healthcare services can provide chronic condition monitoring in the early stages of diseases and help execute decisive medical action in emergencies. However, thus far, the application of U‐Healthcare systems has been limited to diseases such as obesity, diabetes, etc. Acute myocardial infarction (AMI) is among the most critical chronic diseases and requires early detection and treatment. In this paper, we propose an AMI diagnostic software technique and protocol that can support real‐time communication between the patient and medical personnel. Our monitoring and diagnostic system has been developed using a protocol based on ISO/IEEE 11073. When data is transferred from the patient's smartphone to a server in hospital, the medical personnel consult the patient's biosensor data to determine the status of the relevant disease and provide appropriate medical service. The relevant information is sent back to the patient's smartphone through a wireless network, and patients can view their data in graphical format through their smartphone. Copyright © 2015 John Wiley & Sons, Ltd.