Preparation and characterization of graphene nanosheets dispersed pyrrole-chorobenzaldehyde-heptaldehyde conjugated terpolymer nanocomposites for DNA detection

A new conductive terpolymer/graphene nanosheet hybrid composite has been synthesized by polymerizing pyrrole, chlorobenzaldehyde, and heptaldehyde (PPyCB&;H), in the presence of graphene nanosheets (GNS), using p-toluene sulfonic acid as a catalyst. Fourier transform infrared spectra, proton nuclear magnetic resonance, transmission electron microscopy, and X-ray diffraction patterns confirm the formation of PPyCB&;H/GNS hybrid nanocomposites. Further, the resultant nanocomposite material is coated on ITO to construct an electrochemical sensor for the reliable detection of single-strand DNA (tDNA) which is cleaved from the genomic DNA of Escherichia coli. Under optimized conditions, linear detection of genomic DNA (tDNA) with concentration ranging from 1.3 × 10⁻¹² to 1.3 × 10⁻²³ M is observed and it is repeatable with a 1.3 × 10⁻²³ M lowest level detection limit. The present modified electrode of PPyCB&;H/GNS may show utility for constructing highly sensitive electrochemical sensors for the detection of E. coli.

Graphical abstract

     

Synthesis and photophysical,antibacterial studies of some novel molecular tweezers

Zeroth and first generation dendritic wedges with thiophene amide as surface group and 1, 2, 3-triazole as bridging unit which can function as molecular tweezers are synthesised by both convergent and divergent approaches. All the synthesised dendritic wedges displayed the absorbance band between 256 and 294 nm and fluorescence maximum between 357 and 528 nm supporting their self complementary property. Dendritic wedge 5 showed better antibacterial activity than other dendritic wedges in the assay against the human pathogens viz Staphylococcus aureus, Escherichia coli, Bacillus cereus and Klebsiella pneumonia and the dentritic wedge 5 was also effective in the computational molecular docking studies.     

Octahedral oligomeric silsesquioxane (OAPS and OG) - Polyimide hybrid nanocomposite films: Thermo-mechanical,dielectric and morphology properties

Abstract

The nano-sized SQS based polyimides have been successfully synthesized with different oxide groups such as phosphineoxide, sulfone and siloxane as in the backbone of polymer. The SQS-Polyimide nanocomposites prepared through the condensation process using amine and epoxy functionalized SQS as precursor. The presence of SQS in the resulting polyimide nanocomposites was confirmed by FTIR and XRD analyses. The presence of SQS and greatly enhances the char yield to an extent of 16% when compared to that of neat polyimide. The incorporation of SQS into polyimide lowered the value of dielectric constant from 3.31 to 2.09 at 1?MHz and the value of thermal expansion coefficient from 56.6 to 42.7?ppm/K. The composites sample prepared using 20?wt% SQS possess the lowest value of dielectric constant and CTE value. The hydrophobic nature of SQS contributes to lower the water uptake of composites from a value of 2.76 (neat polyimide) to 2.42 for POS-PI containing 20?wt% SQS. Further, the SQS polyimide composite systems possess the enhanced values of thermal stability and glass transition temperatures according their percentage weight. Data obtained from different studies, it is suggested that these hybrid composites can be used as an effective insulation materials for high performance microelectronics applications.     

Chiral and Achiral 1,3,4‐Oxadiazolophanes: A New Class of Cyclophanes in Supramolecular Chemistry

The synthesis of novel oxadiazolophanes with chiral (S)‐BINOL and methylene bis‐naphthyl as building blocks has been achieved by one pot reaction with simple and mild condition.     

Aminoquinoline based highly sensitive fluorescent sensor for lead(II) and aluminum(III) and its application in live cell imaging

We have synthesized a new probe 5-((anthracen-9-ylmethylene) amino)quinolin-10-ol (ANQ) based on anthracene platform. The probe was tested for its sensing behavior toward heavy metal ions Hg²⁺, Pb²⁺, light metal Al³⁺ ion, alkali, alkaline earth, and transition metal ions by UV–visible and fluorescent techniques in ACN/H₂O mixture buffered with HEPES (pH 7.4). It shows high selectivity toward sensing Pb²⁺/Al³⁺ metal ions. Importantly, 10-fold and 5- fold fluorescence enhancement at 429 nm was observed for probe upon complexation with Pb²⁺ and Al³⁺ ions, respectively. This fluorescence enhancement is attributable to the prevention of photoinduced electron transfer. The photonic studies indicate that the probe can be adopted as a sensitive fluorescent chemosensor for Pb²⁺ and Al³⁺ ions.