Biosensors for the control of environmental parameters
This work presents the design/development of biosensors based on metal supported bilayer lipid membranes (s-BLMs), intended for the qualitative and quantitative detection of substances of environmental interest. Biosensor design proceeds through a knowledge-based approach that takes into consideration environmental constraints, needs, and parameters, followed by analytical development and validation. Two case examples are presented: (i) polycyclic aromatic hydrocarbons (PAHs) monitoring in estuarine areas, and (ii) hyperoxide-based detection. The former is used to illustrate the functionality of the knowledge-based design, whereas the latter follows analytical development protocols (construction, physicochemical characterization, performance evaluation). The hyperoxide sensor was built on egg phosphatidylcholine (egg PC) membranes incorporated with horseradish peroxidase, whereas two immobilization techniques have been tested: physisorption of the enzyme at the pre-formed bilayer and addition of the enzyme into the lipid forming mixture prior to BLM self- assembly. The sensor has been validated using commercial hyperoxide formulations. The results indicate that hyperoxide can be rapidly screened using the present metal- supported BLM-based minisensor. The approach provides response times of seconds and detection sensitivity and limits for hyperoxide that are suitable for direct analysis of industrial or environmental samples without preconcentration (although sample preparation to eliminate other adsorbents to BLMs may be necessary). While the work presented here represents an attractive configuration and application of electrochemistry of BLM-based sensors, the practical use of such a sensor for real world applications needs to be further researched for robustness, lifetime, manufacturability, and other performance requirements that will further allow commercialization of the present device.