Nikolas Psaroudakis

Potentiometric cholesterol biosensing application of graphene electrode with stabilized polymeric lipid membrane

A novel potentiometric cholesterol biosensor has been fabricated through the immobilization of the stabilized polymeric lipid membrane onto graphene electrode. The stabilized polymeric lipid membrane is composed of cholesterol oxidase enzyme and polymerization mixture; which holds paramount influence on the properties of the cholesterol biosensor. The presented biosensor reveals an appreciable reproducibility, good selectivity and high sensing capability with a linear slope curve of ∼64 mV per decade. The strong biocompatibility among stabilized polymeric lipid membranes and human biofluids provides the possibility to use for real blood samples and other biological applications.Graphical abstract

Construction of a Simple Portable Optical Sensor Based on Air Stable Lipid Film with Incorporated Acetylcholinesterase for the Rapid Detection of Carbofuran in Foods

This work describes the construction of a simple portable optical biosensor for the rapid, selective, and sensitive detection of carbofuran in foods using air stable lipid films with incorporated acetylcholinesterase. The stabilized substance supported on a polymer lipid film on a glass fiber filter was formed on the filter by polymerization using UV (ultra-violet) radiation prior its use. Methacrylic acid was the functional monomer, ethylene glycol dimethacrylate was the crosslinker, and 2,2′-azobis-(2-methylpropionitrile) was the initiator. Acetylcholinesterase was incorporated within this mixture prior to the polymerization. The polymerization process took place by using UV irradiation. The polymerized lipid films without this enzyme provided fluorescence under a UV lamp. The presence of the enzyme in these films quenched this fluorescence. A drop of aqueous solution of acetylcholine provided a “switching on” of the fluorescence, which allowed the rapid detection of this compound at the levels of 10−8 M concentrations. These lipid membranes were used for the rapid detection of pesticides. Carbofuran was chosen as a typical pesticide. A drop of carbofuran in the filters quenched again the fluorescence. Carbofuran could be determined at concentration levels of 10−7 to 10−9 M. The investigation of the effect of potent interferences included a wide range of compounds usually found in foods and also of proteins and lipids. The technique was applied in real samples of fruits, vegetables, and dairy products. This allowed the rapid detection of the pesticide in markets and in the field.

Rapid flow injection electrochemical detection of 3,3′,4,4′ tetrachlorobiphenyl using stabilized lipid membranes with incorporated sheep antibody

AbstractAn electrochemical biosensor based on a supported polymerized lipid film with incorporated sheep anti-3,3′,4,4′ tetrachlorobiphenyl (PCB congener 77) antibody using flow injection analysis was developed. The polymerized lipid film contained 85% (w/w) dipalmitoylphosphatidylcholine (DPPC) and 15% (w/w) dipalmitoylphosphatidic acid (DPPA), methacrylic acid, ethylene glycol dimethacrylate, AIBN and sheep anti-congener 77 antiserum. Congener 77 was injected into flowing carrier electrolyte and the flow stopped to detect the antigen. These membranes gave only a single transient proportional to log [congener 77] from 10−8 to 10−5 M, with a detection limit of ca. 10−8 M. A membrane containing 35% (w/w) DPPA was used to examine regeneration. The maximum number of cycles was about 5.

Biosensors for Security and Bioterrorism: Definitions, History, Types of Agents, New Trends and Applications

Biosensors are making a large impact in environmental, food, biomedical, and in many other applications. They provide many advantages. in comparison to standard analytical detection methods (i.e., chromatographic techniques) such as minimal sample preparation and handling, faster time analysis, simpler steps of analysis, rapid detection of the analytes of concern, use of non-skilled personnel, and portability for uses in the field applications. The aim of this chapter is to focus on novel research related to the rapid detection of agents and weapons of bioterrorism and provide a comprehensive review of the research topics most pertinent to advancing devices applicable to the rapid real-time detection of toxicants and bioterrorism weapons such as microbes, pathogens, toxins, virus, or nerve gases. The ongoing war on terrorism and the rising security concerns are driving the need for newer faster biosensing devices against bio-warfare agents for both military and civil defense applications. Readers of these review article will learn new schemes of biological weapons that can lead to the construction of devices that will minimize the risk of bio-terrorism.