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Ultrathin films of a cross-linked and chemically distinct conjugated poly(p-phenylene) network via electropolymerization are described. The amphiphilic network precursor was synthesized by incorporating the alkoxy carbazole group (−O(CH2)5Cb) to a poly(p-phenylene) (C6PPPOH) backbone. In order to investigate the combined thin film electrochemical and photophysical properties of poly(p-phenylene)s and polycarbazole conjugated polymers, C6PPPC5Cb was deposited on substrates using the Langmuir Blodgett Kuhn (LBK) method. The monolayer isotherm of the polymer, C6PPPC5Cb, showed a liquid expanded region slightly different from the parent polymer C6PPPOH. Multilayers (up to 30 layers) were transferred to different substrates such as quartz, gold coated LaSFN9 and ITO substrates for analysis. For conversion to a conjugated polymer network (CPN) film, the electroactive carbazole group was electropolymerized using cyclic voltammetry (CV) resulting in polycarbazole linking units. The differences in the film properties and corresponding changes in the electrochemical behavior indicate the importance of film thickness and electron/ion transport process in cross linked network films. From the electrochemical studies, the scan rate was found to have a considerable effect on electropolymerization with higher oxidation and reduction peak values found for the rigid network polymer compared to the uncrosslinked polymers. [ABSTRACT FROM AUTHOR]

Protein microarrays are promising tools that can potentially enable high throughput proteomic screening in areas such as disease diagnosis and drug discovery. A critical aspect in the development of protein microarrays is the optimization of the array's surface chemistry to achieve the high sensitivity required for detection of proteins in cell lysate and other complex biological mixtures. In the present study, a high-density antibody array with minimal nonspecific cellular protein adsorption was prepared using a glass surface coated with a poly(propyleneimine) dendrimer terminated with carboxyl group (PAMAM-COOH). The carboxyl-terminated dendrimer-modified surface has almost similar nonspecific cellular protein adsorption when compared to an inert PEG-modified surface. In addition, the multiple functional sites available for reaction on the dendrimer surface facilitated high-density immobilization of antibodies and efficient capture of bioanalytes. Various molecules were tested for their ability to block or deactivate the reactive carboxyl surface after antibody immobilization to further reduce the nonspecific binding. A short oligoethylene glycol (NH2-d4-PEG-COOH), was found to significantly improve the signal-to-noise ratio of the assay, resulting in higher sensitivity. The properties and functional qualities of the various surfaces were characterized by contact angle and AFM measurements. Nonspecific protein adsorption and protein immobilization as a function of dendrimer generations and sensitivity of antigen capturing from a buffer (1 pM) as well as from the complex cell lysate (10 pM) system were examined. Our detailed experimental studies demonstrated a facile method of preparing surfaces with high protein loading and low nonspecific protein binding for the development of high sensitivity protein microarrays. [ABSTRACT FROM AUTHOR]

Formation and characterization of nanocrystallite spheres from a hybrid of functionalized cross-conjugated poly(p-phenylene) and C60are reported. [ABSTRACT FROM AUTHOR]

A homologous series of polyhydroxylated poly(p-phenylene)s with different alkoxy groups (C6PPPOH, C12PPPOH, and C18PPPOH)were synthesized with use of the Suzuki polycondensation reaction. Comparative studies of the structure correlation between their photophysical properties and film morphology is described. The absorption and emission spectra of polymers in solution and thin films showed similar features indicating that the electronic properties in solution were retained in the film state. Compared to the polymer with the short alkoxy chains (C6PPPOH), the polymers with long alkoxy groups (C12PPPOH and C18PPPOH) showed improved film forming properties with continuous and smooth film morphology. The absorption properties of the C12PPPOH showed an enhanced effective conjugation length and high quantum yield implying planarization of the backbone through alkoxy chain packing (C12H25O-) and potential hydrogen bonds. No overlap in the absorption and emission spectra was observed, which indicated minimized excimer formation or excitation energy transfer in the films. Time-resolved fluorescence measurements showed that the decay times increased from 43 ps (C6PPPOH) to 78 ps (C12PPPOH) and 99 ps (C18PPPOH). Electrochemical studies were performed for all polymers and the observed oxidation potential for C6PPPOH was higher than that of C12PPPOH and C18PPPOH. In addition, the C12PPPOH has the lowest band gap of E 2.59 eV when compared to the 3.1 (C6PPPOH) and 2.61 eV (C18PPPOH) gaps. The optical band gaps estimated from the absorption onset of the polymers are significantly higher than those obtained from electrochemical data. C12PPPOH was chosen for investigating the charge carrier mobility by the time-of-flight (TOF) technique. The observed results also showed negative field dependent values of the drift mobility for the polymer C12PPPOH. [ABSTRACT FROM AUTHOR]

Morphosynthesis of calcium-rich materials by tuning the chemical structure of organic matrices has tremendous potential in the preparation of functional mineralized materials. In this paper, we have demonstrated the deposition of thin films of CaCO3by subtle modifications of the backbone of poly(methyl methacrylate) (PMMA) by the incorporation of many hydroxyl groups. The water-insoluble hydroxylated PMMA (HyPMMA) was used as a template along with poly(acrylic acid) (PA) as an additive for CaCO3mineralization. Thin film deposition was controlled by the addition of an appropriate amount of PA to the crystallization medium. At lower concentrations (PA 50 and 100 g/mL), irregular aggregates of calcite crystallites were formed. As the concentration of PA was increased (500 g/mL and 1 mg/mL), calcite thin films were deposited. Time-dependent crystallization showed that the precipitates obtained after 3 h were biphasic in structure, consisting of both amorphous and crystalline domains. Observations suggest that crystal aggregates and thin films were formed through a multistep mechanism in which an amorphous phase was deposited initially and was subsequently transformed into stable crystalline form. In contrast, mineralization in the presence of HyPMMA or PA alone yielded only calcite or calcite aggregates. Our results indicate that a concerted interplay of interactions between the insoluble polymer matrix (HyPMMA) and soluble PA determines the growth and morphology of CaCO3by influencing the transformation of amorphous calcium carbonate (ACC) into the crystalline phase. More specifically, we have investigated the interplay of the role of acid groups on PA and accelerating alcohol groups on HyPMMA in calcium carbonate crystallization. [ABSTRACT FROM AUTHOR]