A Platform for Fast Detection of Let-7 Micro RNA Using Polyaniline Fluorescence and Image Analysis Techniques

The project describes a new strategy for transducing hybridization events through modulating intrinsic properties of the electroconductive polymer polyaniline (PANI). When DNA based probes electrostatically interact with PANI, its fluorescence properties are increased, a phenomenon that can be enhanced by UV irradiation. Hybridization of target nucleic acids results in dissociation of probes causing PANI fluorescence to return to basal levels. By monitoring restoration of base PANI fluorescence as little as 10-11 M (10 pM) of target oligonucleotides could be detected within 15 minutes of hybridization. Detection of complementary oligos was specific, with introduction of a single mismatch failing to form a target-probe duplex that would dissociate from PANI. Furthermore, this approach is robust and is capable of detecting specific RNAs in extracts from animals. This sensor system improves on previously reported strategies by transducing highly specific probe dissociation events through intrinsic properties of a conducting polymer without the need for additional labels. The change in fluorescence property of PANI by oligo immobilization and hybridization with mimic let-7 is measured by fluorescence microscope and the image analyzed by MATLAB. A heuristic algorithm determines color threshold of the fluorescent active image. This image segmentation helps to determine the average pixel intensity representing the active image foreground of PANI fluorescence triggered by DNA immobilization and hybridization process. This would help us to quantify response of PANI based biosensor for detecting micro RNA let-7

Synthesis, characterization and physicochemical studies of copolymers of aniline and 3-nitroaniline

Polyaniline (PA), the versatile conducting polymer, owing to its tunable optoelectronic properties, facile preparation methodology and reversible redox behavior, has elicited much interest among current researchers, particularly in the fields of energy generation storage devices, protective coatings and electrochemical sensors. However, its commercialization has been much restricted due to low solution processability and thermal stability. Recent studies reveal that the above-mentioned challenges can effectively be addressed by copolymerization of PA with suitable components. In addition, the properties of copolymers could be modified and tuned by varying the monomer ratios. Thus, the present work is concerned with the fabrication of poly(aniline-co-3-nitroaniline) with varying compositions obtained by in situ oxidative copolymerization of aniline and 3-nitroaniline by altering the molar ratio of monomers. Optimization of the physicochemical properties such as UV visible absorption, solubility, thermal stability, electrical conductivity and dielectric signatures, particle size and morphology was achieved by varying the composition of monomeric substituents in these copolymers. Smoother morphology of the copolymer films was revealed by morphological studies via AFM technique and supported by particle size distribution study. The physicochemical trends demonstrated that proper proportions of nitro (NO2) group in the polymer chain are essential to achieve desired optimal physicochemical properties. Therefore, copolymers are ideally appropriate for multifaceted applications and would promote wider usage of conjugated polymers in various fields of organic-based optoelectronic as well as energy storage devices in the near future.Scopu

PANI-derived polymer/Al2O3 nanocomposites: synthesis, characterization, and electrochemical studies

This paper presents the physicochemical, conductive, and electrochemical properties of different polyaniline (PANI)-derived polymer/Al2O3 nanocomposites synthesized by chemical oxidation polymerization method carried out in two stages: first, activation of the surface of the Al2O3 nanoparticles by hydrochloric acid and second, polymerization of 2-chloroaniline (2ClANI), aniline (ANI), and the copolymer (2ClANI-ANI) in the presence of Al2O3 by using ammonium persulfate as oxidant in aqueous hydrochloric acid. XRD and TEM results reveal the growth of the polymers on Al2O3 nanoparticles and the formation of PANI-derived polymer/Al2O3 nanocomposites. FTIR and UV-Vis show a systematic shifting of the characteristic bands of the polymers with the presence of Al2O3 nanoparticles. Moreover, these nanoparticles enhance the thermal stability of the polymers, as found by thermogravimetric analysis (TGA). Although the incorporation of Al2O3 nanoparticles reduces the electric conductivity of the polymers, the resulting nanocomposites still keep high conductivities, ranging between 0.3 × 10−2 and 9.2 × 10−2 S cm−1. As a result, the polymer/Al2O3 nanocomposites exhibit a good voltammetric response. All these synergetic features of the nanocomposites are assigned to the effective interaction of the polymers and Al2O3 particles at nanoscale.This work was supported by the National Assessment and Planning Committee of the University Research (CNEPRU number E-03720130015), the Directorate General of Scientific Research and Technological Development (DGRSDT) of Algeria. The financial support from MINECO is also acknowledged (MAT2013-42007-P project)

Vapor phase infiltration (VPI) and doping of conducting polymers

114 p.In this thesis, the "Vapor Phase infiltration"(VPI), a vacuum based process derived from the atomic layer deposition (ALD), is used for the top-down infiltration and doping of various conducting polymers. In the first part of this thesis, a single precursor vapor phase infiltration (VPI) process to dope polyaniline (PANI) is presented. As dopants, the vaporized Lewis acidic precursors SnCl4 and MoCl5 were used at a process temperature of 150 °C. After 100 cycles, the MoCl5-infiltrated PANI showed the highest conductivity, 2.93 × 10-4 S/cm, which is a significant enhancement of up to 6 orders of magnitude in comparison to undoped PANI. SnCl4-infiltrated PANI showed highest conductivity after 60 cycles with a value of 1.03 × 10-5 S/cm. The second part of this thesis describes the single precursor VPI and doping of poly(3-hexyl)thiophene (P3HT). For the infiltration processes, the Lewis acid MoCl5 was used as precursor at a process temperature of 70ºC. The room-temperature I-V plots show a dependency on the VPI cycles numbers. The highest values show an increase of 5 orders of magnitude for the conductivity, namely from 1.44 x 10-5 S/cm in the as prepared P3HT to 3.01 S/cm after infiltration 100 cycles In the last part of this thesis, the multiple pulsed vapor phase infiltration (MPI) process was applied to dope polyaniline (PANI). For the process, the two typical ALD precursors diethylzinc (DEZ) and deionized water (H2O) were used at a process temperature of 155ºC. The room-temperature I-V polts showed the conductivity of Zn-infiltrated PANI increasing to 18.42 S/cm, up to three orders of magnitude higher than obtained upon conventional doping with 1 M HCl in wet-chemical ways (8.23 x 10-2 S/cm).CIC nanoGUN

Review on Structure, Properties and Appliance of Essential Conjugated Polymers

One of the important classes of polymers is conductive polymers. These polymers mainly comprise of aromatic and aliphatic backbone. Polyaniline is one of most important type of conjugated polymers due to its excellent conductivity and other essential physical properties. Consequently, main focus of this review is structure, properties and application of technically important conjugated polymer. The conducting polymers such as polyaniline, polythiophene, polypyrrole, polyacetylene and pol(p-phenylene) have been discussed. Conductive polymer offers significant conductivity values similar to that of metal and semiconductors. Finally, the uses of polymers in different technical fields such as sensors, rechargeable batteries, photovoltaics, and fuel cells have been conversed