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• Fast and efficient microwave assisted synthesis of a degradable polythiophene-based co-polymer. • Azomethine linkers amongst bithiophene units yield a continuously conjugated, conductive and redox-active framework. • Polymer degradation is a function of the pKa of the acid used to catalyse the hydrolysis with degradation times varying from 1 h to 6 months. • The polymer presents with sufficiently high conductivity for in vivo biomedical applications. As part of ongoing efforts to develop electroactive polymers (EAPs) which are biodegradable/bioresorbable, we report on the microwave assisted synthesis and characterization of an electrically conducting and electroactive polymer that capitalises on p K a sensitivity to initiate the system's fracture and breakdown. The system, poly(bis((thiophen-2-yl) methylene) benzene-1,4-diamine), a poly(thiophene-azomethine) co-polymer (PAZO), incorporates hydrolytically sensitive azomethine linkers amongst bithiophene units resulting in one continuously conjugated and redox-active macromolecular framework. Rapid microwave assisted synthesis allowed for facile preparation of the polymer with significantly reduced reaction times when compared to traditional synthetic routes. Electrochemical analysis indicated quasi-reversible electrochemical behaviour with sufficiently high conductivity for in vivo biomedical applications. The polymer displays tunable degradation behaviour whereby the time duration required for polymeric breakdown is a function of the p K a of the acid used to catalyse the reaction resulting in controllable degradation times ranging from 1 h to 6 months. The development of conductive polymeric materials that are fully degradable over pre-defined time periods opens up a portal to the next generation of EAPs for in vivo biomedical applications. [ABSTRACT FROM AUTHOR]

The electrochemiluminescent (ECL) properties of a luminescent metal centre, [Ru(bpy)3]2+, can be significantly modulated through its electronic interaction with neighbouring centres and the polymer backbone used to confine it on an electrode surface. From the perspective of ECL based sensing devices, an increase in the ECL efficiency of a metallopolymer film can result in enhanced sensor sensitivity and selectivity. This work probes the ECL properties of both conjugated, [Ru(bpy)2(PPyBBIM)10]2+, and non-conjugated, [Ru(bpy)2(PVP)10]2+, ruthenium based metallopolymer films based on a well documented reaction with sodium oxalate, where bpy is 2,2′-bipyridyl, PPYBBIM is poly[2-(2-pyridyl)-bibenzimidazole] and PVP is poly(4-vinylpyridine). Through a combination of ground state electrochemical studies and ECL measurements, the ECL efficiency for each film is determined. This study reveals that despite a dramatic influence in charge transfer rates between metal centres, as observed for the conducting polymer, mediated through the conducting polymer backbone, a corresponding increase in ECL efficiency is not always observed. The degree of communication between the adjacent excited state metal centres are an important consideration for ECL enhancement however self quenching, luminophore distribution and film porosity must also be considered. [ABSTRACT FROM AUTHOR]

Abstract: Immobilisation of a luminescent material on an electrode surface is well known to substantially modulate its photophysical and electrochemical properties. Here a positively charged ruthenium metal complex ([Ru(bpy)3]2+) is immobilised on all electrode surface by ion paring with a sulfonated conducting polymer poly(2-methoxyaniline-5-sulfonic acid), (PMAS). Significantly, our study reveals that the electron transport between the ruthenium metal centres can be greatly enhanced due to the interaction with the conducting polymer when both are surface confined. Charge transfer diffusion rates in the present system are an order of magnitude faster than those found where the metal centre is immobilised within a non-conducting polymeric matrix. Electron transport appears to be mediated through the PMAS conjugated structure, contrasting with the electron hopping process typically observed in non-conducting metallopolymers. This increased regeneration rate causes the ruthenium-based electrochemiluminescence (ECL) efficiency to be increased. The impact of these observations on the ECL detection of low concentrations of disease biomarkers is discussed. [Copyright &y& Elsevier]