Enzyme electrodes are biochemical transducers. They function by converting biochemical reactions into electrochemical processes. This functionality could potentially give rise to a new generation of implantable medical devices such as biofuel cells and biosensors. The main aim of this study was to fabricate and characterise enzyme electrodes for potential use in these applications. The approach involved testing various materials such as different types of enzyme, polymeric electron transfer mediators, enzyme entrapment materials, conductive supports and matrices and biocompatible polymers. Various enzyme immobilisation methods were used and various polymeric electron transfer mediators were fabricated and tested. The investigation was based primarily on electrochemical techniques. The materials and immobilisation techniques presented could potentially be used to improve future enzyme electrodes. This may be achieved through the novel use of biocompatible and biomimicking polymers, through simple biofuel cell fabrication and with the use of multi analyte biosensors developed during this investigation.
The new design of an Impedance measurement based sensor is integrated into the standard 96 wells microtiter plate which is use for characterizing different stimulus hydrogels. The online monitoring of swelling and deswelling of hydrogel is possible with this new system. Hydrogels of Poly-Hydroxyethyle Methacrylate, Poly (HEMA) with different compositions of mixing monomers were used for measurements. These hydrogels which absorbs/desorbs solution in response to changes in surrounding environmental condition polymerized over the sensor with roughly 200µm height. The sensor output voltage response to pH value changes with swelling and contracting of hydrogel. The shift in the resistivity of hydrogel was investigated as function of different mixing monomers ratios and compartment of hydrogel. It was found the concentration of cross-link and water content play significant role in changing resistivity of hydrogel. An additional advantage with new setup its use only 200µl of solution and 200µm thick hydrogel layer in standard 96 wells microtiter plate for characterizing hydrogels.
Advancements in the micro/nano-fabrication techniques have opened up new avenues for the development of portable and easier-to-use biosensors. Over the last few years, carbon electrodes have been widely used as sensing units in biosensors due to their attractive physiochemical properties. This book details different strategies to develop functionalized high surface carbon micro/nano-electrodes for electrochemical and biosensing devices. Carbon electrodes were fabricated via carbon-MEMS technique, which is based on pyrolyzing prepatterned photoresist. To increase the surface area of the carbon electrodes, multiple approaches such as (i) fabrication of porous 3D carbon microarrays, (ii) conformal coating of graphene onto 3D carbon microarrays, and (iii) fabrication of controllable carbon nanostructures were investigated. For carbon surface functionalization to covalently attach biomolecules, different oxidation techniques and the resultant surface carbon–oxygen groups were analyzed and compared. Lastly, label-free detection of platelet-derived growth factor oncoprotein, a cancer biomarker, was demonstrated on 3D carbon microarrays platform with sub-nanomolar detection limit.
The combination of biological molecules and CNTs is of great importance in developing miniaturized sensor devices for future clinical diagnostic and electronics applications. Biosensing technology using aligned CNTs solely depends upon amplified signals generated by biomolecular interactions. Aligned CNTs have huge potential as electrochemical sensors as they provide enhanced electron transfer in redox reactions due to high length to diameter (aspect ratio). CNT based functional devices including transistors, sensor, emitters and energy units require vertically aligned CNTs with a high length to diameter aspect ratio and their ability to mediate electron transfer reactions of electroactive species in solution when used as electrode material. Carbon nanotubes have been proved as better electrode materials than traditional carbon electrodes, clay nanoparticles and conducting polymers etc. due to their proficient charge transfer capability and high chemical stability. Major Aim of this book is to present clear idea to the readers who intend to devise a highly sensitive and efficient vertically aligned CNT based electrochemical sensors.
A new approach of Biosensor for Continuous Ambulatory Peritoneal Dialysis (CAPD) that works only when the waste in your abdomen is over the threshold -not throughout night time-. The solid state chemical/bio ISFET sensor, benefiting from advanced electronic circuit techniques, is now enjoying a revival after 37 years of staying in the shadows. However, this young species needed a lot of nurturing to ensure it reaches maturity and flourishes. Looking back over the work of this research and looking forward to future developments, the book elucidates mandatory steps that will enhance the chances of success of this biosensor, ISFET.
The growing demand for point-of-care analytical systems requires novel miniaturised and sophisticated sensor systems. This book describes the development of an all-polymer biosensor platform for electrochemical detection of analytes from liquid media. Conductive polymers were employed for the electrical structures, while aptamers were used as recognition elements. The wide range of applicability of this sensor is shown on the basis of three different analytical challenges.
Biosensor employing organelles in immobilized form are widely used in environmental monitoring. These immobilized organelles play vital role in sensitivity, accuracy, and stability of the biosensor system. Some of the organelle used for immobilization is whole cell, protein, enzyme and DNA. Traditionally biosensor used whole cell from one individual strain of microorganism. This concept limits the biosensor detection to certain specific samples alone. Detection of the content of the samples depends on the properties of the immobilized microbial cell. For detection of broad range of samples, novel biosenor using mixed microbial cultures is being designed in this dissertation.
Heroine is synthetic derivative of morphine, a naturally occurring substance extracted from unripe seeds or capsules of Papaver somniferum (poppy plant). The use of heroine and morphine as a recreational drug has reached epidemic proportion, largely because of increased availability. The currently used techniques for the detection of opiate drugs are time consuming, expensive and not amenable to on-site application. This book describes about development of a highly sensitive, fast, reliable, field applicable and cost effective immunoassay/ immunobiosensor for the detection of opiate drugs: morphine and heroin, the most addictive and commonly abused narcotics. Various types of immunoassay are described in this book using enzyme, fluorophore, carbon nanotubes, gold nanoparticles and phage display detection which shows detection limit in the ppb range without the aid of any sophisticated instrument.
In this technique, the production of molecular framework and polymer is done using meta acrylic acid monomers, which are formed via covalence connection between meta acrylic acid monomers (MAA) of white polymer. Here also hydrogenic connection between exotoxin amino acid and meta acrylic acid is made that would function as the selective absorption for that. Then in the second stage, based on the bacterial antibody connection to nanoparticel, a sensor was used. In this part of the research, as the basis for absorption for the recognition of bacterial toxin, medium sized silica nanoparticles of 10 nano meter in form of solid powder were utilized with Notrino brand. Then the suspension produced from agent-linked nanosilica which was connected to bacterial antibody was positioned near the samples of distilled water, that were contaminated with Staphylococcus Aureus bacterial toxin with the density of 10-3, so that in case any toxin exists in the sample, a connection between toxin antigen and antibody would be formed. Finally, the light absorption related to the connection of antigen to the particle attached antibody was measured using spectrophotometry.
Nowadays,detection of a single-base polymorphism is thought to be the key for diagnosis of about 400 genetic diseases and,realization of personalized medicine in order to develop therapeutics.The other hand,the integration of new emerging nanomaterials(graphene)with sensors and devices have revealed an enormous potential for the future application of highly sensitive and selective DNA biosensors.All these approaches open up the routes for genetic researchers to understand the progression and early screening of diseases,or forensic analysis by tailoring the electrical properties of graphene,which make the controlled design of these sensors essential.In this research study, numerical model of the graphene-based liquid-gated sensors with DNA sensing application is developed to help in understanding the sensing mechanism of these sensors which is the matter of dispute these days.The results are compared with the experimental work and an acceptable agreement is observed. We found that numerical modeling needs optimization to be closer to the realistic results.So, particle swarm optimization technique is used to achieve a more accurate and reliable model for DNA hybridization detection.