Recent Advances in Polymeric Materials Used as Electron Mediators and Immobilizing Matrices in Developing Enzyme Electrodes

Abstract

Different classes of polymeric materials such as nanomaterials, sol-gel materials, conducting polymers, functional polymers and biomaterials have been used in the design of sensors and biosensors. Various methods have been used, for example from direct adsorption, covalent bonding, crossing-linking with glutaraldehyde on composites to mixing the enzymes or use of functionalized beads for the design of sensors and biosensors using these polymeric materials in recent years. It is widely acknowledged that analytical sensing at electrodes modified with polymeric materials results in low detection limits, high sensitivities, lower applied potential, good stability, efficient electron transfer and easier immobilization of enzymes on electrodes such that sensing and biosensing of environmental pollutants is made easier. However, there are a number of challenges to be addressed in order to fulfill the applications of polymeric based polymers such as cost and shortening the long laboratory synthetic pathways involved in sensor preparation. Furthermore, the toxicological effects on flora and fauna of some of these polymeric materials have not been well studied. Given these disadvantages, efforts are now geared towards introducing low cost biomaterials that can serve as alternatives for the development of novel electrochemical sensors and biosensors. This review highlights recent contributions in the development of the electrochemical sensors and biosensors based on different polymeric material. The synergistic action of some of these polymeric materials and nanocomposites imposed when combined on electrode during sensing is discussed.

Facilitating electron transfer in bioelectrocatalytic systems

“…The mediator can be retained on the surf ace by electrostatic interactions, f or ex ample in polyelectrolyte membranes 79 or due to hydrophobic-hydrophilic interactions in polymer matrices. 80 For more inf ormation on mediated bioelectrocatalytic systems with dif f usional mediators see the Review P aper. Despite the productivity of ET processes in bioelectrocatalytic systems utilising soluble dif f usional electron mediators, they suf f er f rom an inherent drawback: the mediating species can easily dif f use away f rom the electrode surf ace into the bulk solution and that causes sample contamination and low long-term operational stability of the system.…”

Voltammetry: A Brief Review About Concepts

“…Esta adsorção pode ocorrer espontaneamente na superfície de um eletrodo comum, 48-50 ou pode-se fazer uso de um eletrodo quimicamente modificado para se conseguir tal adsorção. Essa modificação pode ser obtida não apenas por eletrodeposição, na qual filmes metálicos finos ou mesmo de óxidos são depositados, mas, sobretudo, em sistemas nos quais ligações com agentes de intercruzamento como glutaraldeído [51][52][53][54] e epicloridrina 55-57 são empregados a fim de fixar sobre a superfície dos eletrodos algum substrato de interesse.…”

Electroanalytical Sensor Technology

“…The incorporation of bio-materials [161,162] into electrochemical sensors enables a level of selectivity that is comparable to that seen in nature, with the majority of advancements i n b i o s e n s o r s d u e t o t h e i m m o b i l i z a t i o n o f a b i o l o g i c a l m a t e r i a l ( a n d h e n c e i t ' s physiochemical properties to an electrode's surface electrode [163,164]. Mimicking nature selectivity has been attempted with the use of molecularly imprinted polymers but so far has not rivalled the selectivity of biomolecules such as antibodies, nucleic acids, aptamers, etc.…”