This paper is concerned with a novel layer-by-layer adsorption method for preparing multilayer assemblies of polymeric materials. We employed two kinds polymers, poly[2-(9-carbazolyl)ethyl methacrylate] and poly[2-[(3,5-dinitrobenzoyl)oxy]ethyl methacrylate], both bearing nonionic pendant groups in the side chains which have electron-donating character and electron-accepting character, respectively. These polymers were alternatively adsorbed onto the gold surface and the quartz substrates from the solutions in methylene chloride. The formation of this multilayer assembly is based on the charge-transfer (CT) interaction between these groups at the solid−liquid interface and the films obtained have periodic layers of CT complexes. The successive increase of the thickness could be easily monitored by surface plasmon measurements. The thickness increment increased with the increase in the number of layers, and the increment became constant around the 10th layer, indicating that the total thickness of the film increases linearly by the alternating adsorption of the counter polymer.

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A layer-by-layer film could be fabricated on a substrate by the consecutive adsorption method based on the charge-transfer (CT) interaction between electron-donating carbazolyl groups and electron-accepting 3,5-dinitrobenzoyl groups in the side chains of two kinds of methacrylate polymers, poly[2-(9-carbazolyl)ethyl methacrylate] (PCzEMA) and poly [2-[(3,5-dinitrobenzoyl)oxy]ethyl methacrylate] (PDNBMA), respectively. The film was characterized by surface plasmon (SP) and UV-vis absorption measurements. The thickness of each layer in the film could be determined by the SP measurements. In the UV-vis absorption measurements, the absorbance of the CT complex increased linearly with the increase in the number of adsorption cycles, indicating that the steady growth of the film took place by immersing the substrate alternatively in the 1,2-dichloroethane solutions of each polymer. Furthermore, the decrease in the absorbance of carbazolyl groups was observed on the immersion of the film with the PCzEMA surface in the solution of PDNBMA. This indicates the formation of the CT complex between adjacent polymer layers. The multilayered structure of the obtained film showed an excellent thermal stability up to 200 °C.

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Digital PCR (dPCR) is a promising method for performing liquid biopsies that quantifies nucleic acids more sensitively than real-time PCR. However, dPCR shows large fluctuations in the fluorescence intensity of droplets or wells due to insufficient PCR amplification in the small partitions, limiting the multiplexing capability of using the fluorescence intensity. In this study, we propose a measurement method that combines dPCR with melting curve analysis for highly multiplexed genotyping. A sample was digitized into a silicon chip with up to 2 × 104 wells in which asymmetric PCR was performed to obtain more single-stranded amplicons that were complementary to molecular beacon probes. Fluorescence images were captured while controlling the temperature of the chip, and the melting curve was measured for each well. Then, genotyping was performed by using the fluorescence intensity, the dye color of the probe, and the melting temperature (T m). Because the T m of the PCR products is not highly dependent on the amplification efficiency of PCR, genotyping accuracy is improved by using T m values, enabling highly multiplexed genotyping. The concept was confirmed by simultaneously identifying wild-type KRAS, BRAF, and eight mutants of these genes (G12D, G12R, G12V, G13D, G12A, G12C, G12S, and V600E) through four-color melting curve analysis. To the best of our knowledge, this is the first demonstration of the genotyping of 10 DNA groups including single mutations of cancer-related genes by combining dPCR with four-color melting curve analysis.

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A highly thermoconductive resin with branched filler is reported. The filler was fabricated by calcination of aluminium isopropoxide adsorbed onto paper filter (cellulose fibers). Scanning electron microscopy and x-ray diffraction measurement demonstrated that the filler consists of α-alumina nanofiber with a branched structure. The thermal conductivity of the filler-resin nanocomposite was two to five times larger than that predicted by the well-known Bruggeman equation, which postulates the composite with spherical filler in the matrix. The branched shape of the α-alumina nanofiber increased the probability of formation of phonon paths with lower thermal resistance, leading to the high thermal conductivity of the nanocomposite.

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