Research Progress in Area 2 方向 ( 二 ) 課題進展 129 Abstract Algae are extremely harmful for both the environment and human health, since they release various biotoxins. Thus, their fast detection with a high-throughput, environmentallyfriendly, fast, and accurate detection method in seawater is of great importance. In this project, a microfluidic chip system based on on-chip three-microelectrode cells specific to marine toxins will be developed. Several electrochemical immunosensing transduction mechanisms and their components will be investigated to build a highly selective and high-throughput microfluidic chip sensor for the detection of various biotoxins. Multiple sensing chips will be integrated with a multichannel polydimethylsiloxane (PDMS) microfluidic platform, which will be applied to detect tetrodotoxin and other marine biotoxin (MTXs) compounds in real seawater. Research Activities and Progress • Developed and streamlined nanofabrication, electroplating, and monolayer synthesis methods to enable higher throughput sensor testing; • Explored selective monolayer desorption as a method for the signal output; • Investigated the effects of pH and ionic strength on an indirect transduction mechanism; • Tested multiple different redox probes with different ionic characteristics to determine the species with the highest stability and current output; • Fe3O4@polydopamine nanoparticles were synthesized for testing the facile extraction of tetrodotoxin from seawater. Key Findings • Oxidative desorption of thiol monolayers is a complex electrochemical process with multiple steps that are highly dependent on monolayer composition; • Redox probe behavior is dominated electrostatic interactions between the probe and negatively charged biorecognition layer; • A pH of 4.5 generates sufficient electrostatic shielding to maximize ferricyanide reduction; • The ionic strength of seawater disrupts antibody-antigen interactions, necessitating a microfluidic-compatible extraction strategy. Research Output Publication 8 Patent 1 Trained personnel 4 High-throughput Detection of Marine Biotoxins in Seawater by an Interdigitated Array Microelectrodes-microfluidic Chip System Prof. Minhua Shao The Hong Kong University of Science and Technology Fig 1. Indirect detection transduction schematic (a) and differential pulse voltammetry results at each step in the biorecognition layer preparation process and before and after introduction of specific antibodies (b).
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