Polymer materials in biosensors

From the Lab to the Field: Organic Materials for Industrial Applications and Environmental Remediation

Many new developments for different industries have their origin in basic science. In recent years, this trend has gained attention due to the increasing interaction between academic science and industry. This article presents some rational materials for chemical modifications that were developed by the basic science, then transferred to the productive sector. Conducting hydrophobic coatings for aerospace applications, hydrogels for the oil and gas industry, as well as polymers for removal of heavy metal, were some of the topics approached in the lab to solve industrial problems. Many times, nature is a great source of inspiration to produce new materials. In this sense, superhydrophobicity and superhydrophilicity (concepts closely related to our everyday life) were the bioinspiration for the development of membranes. These membranes were able to separate hydrocarbons and water, which found application in the treatment of subterranean water for the oil and gas industry.

Chemiluminescent biosensors based on porous supports with immobilized peroxidase

Combining a sensitive and fast chemiluminescence detection method with novel immobilization methods for horseradish peroxidase (HRP) has enabled us to develop sensitive sensors for hydrogen peroxide and the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). HRP biospecific immobilization was shown to have well-defined advantages in terms of a higher specific activity of the enzyme of the surface and a greater sensitivity in the enhanced chemiluminescence (ECL) reaction. The lower detection limit for hydrogen peroxide was 0.025 nmol with HRP immobilized on nitrocellulose membrane through avidin-biotin linkage. An immunosensor for the detection of 2,4-D provides a lower detection limit of 0.2 microgram/l with specific antibodies covalently immobilized on photoactivated nylon. The assay with chemiluminescent detection was also characterized with a wider concentration range when compared with the colorimetric assay.

Biosensors for chemical and biological agents of defence interest

This review discusses current developments in biosensors for toxic materials of defence interest with particular emphasis on the biological element of such devices. A wide variety of synthetic chemicals, toxins of plant or animal origin and biological materials--including various disease micro-organisms as well as some bacterial exotoxins--have either been used as warfare agents or are perceived as having the potential to be used for that purpose. Although an enormous effort is being put into developing biosensors, relatively few analytes, especially toxic materials, can yet be measured by commercially available devices. The factors which currently mitigate against the use of enzyme, natural receptor or antibody based biosensors for unattended continuous environmental monitoring of toxic materials include the inherent instability and availability of suitable proteins and--for receptors and antibodies--the essentially irreversible nature of the binding event, which necessitates a continuous supply of reagents for sequential measurements. Assays involving antibody or DNA based biosensors are time consuming when working in a hazardous environment. Nevertheless, biosensors are capable of being used for extremely sensitive and specific on-site measurements of contamination by specific toxic materials. Methods for improving the stability, extending the range and altering the binding characteristics of sensing molecules are discussed.

Interface analysis in biosensor design

In a survey, the analytical tools to characterise and optimise properties and stabilities of interfaces in thin film biosensors are discussed. After an introduction to microscopic and spectroscopic techniques and different transducers, case studies are presented. They concern bioaffinity sensors with particular emphasis on biomimetic recognition structures, catalytic sensors, transmembrane sensors, cell sensors, and the ambitious goal of addressing individual biomolecular function units.