New Bioanalytical Approaches, Magneto Immunoassays and SIRE Technology Based Biosensors

Research output: ThesisDoctoral Thesis (compilation)


This thesis presents two new technologies, SIRE technology based biosensors and magneto immunoassays, which can be used for bioanalytical applications. One of the main problems associated with biosensor technology is the instability of the recognition element since it is of biological origin and thus, has a limited lifetime. Conventionally, this problem has been solved by immobilizing the biological recognition element directly to the transducer surface, thereby, stabilizing the biomolecule and allowing for its reuse. Biosensors based on Injection of the Recognition Element (SIRE) have tried to solve the instability problem by using fresh enzyme with every measurement. The SIRE biosensor is based on a flow injection principle where a small amount of the native enzyme is injected into an internal buffer flow. The enzyme is held in direct spatial contact with the electrochemical transducer by entrapment using a semipermeable membrane. Differential measurements are performed with the SIRE biosensor allowing for control of matrix interferences. The development of the SIRE technology, as well as some clinical and industrial applications of the sensor are presented. In particular, the detection of metabolites (glucose, hydrogen peroxide, ascorbic acid and lactate) in crude samples (whole blood, cereal, baby food and tomato paste) is demonstrated. The limit of detection for the SIRE biosensor is in the micromolar range.

In the second half of the thesis, the development of a new immunoassay technology based on one of the fundamental forces in nature, magnetism is presented. The magneto immunoassay technology combines the highly selective traditional immunoassay method with a new labeling technology to provide a rapid single-step analysis. The use of superparamagnetic nanoparticles as labels to antigens in heterogeneous immunoassays is demonstrated. The feasibility of using magnetic labels in immunoassays was first investigated by employing a two-site or “sandwich” assay for the detection of Concanavalin A in-buffered samples. The subsequent development of a rapid (10 minute) one-step competitive magneto immunoassay for the detection of human albumin and C-reactive protein is presented, where the limit of detection was determined to be 6 mg/l and 9.8 mg/l, respectively. The competitive assay system was applied to clinical samples (urine) for the detection of human albumin.


  • Kirstin Kriz
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Biochemistry and Molecular Biology


  • Biochemical technology, Biokemisk teknik, antigens, superparamagnetic nanoparticles, magnetic inductance transducer, competitive magneto immunoassay, enzymes, metabolites, differential measurements, SIRE, biosensor
Original languageEnglish
Awarding Institution
Supervisors/Assistant supervisor
  • [unknown], [unknown], Supervisor, External person
Award date2003 Jan 17
  • Department of Pure and Applied Biochemistry, Lund University
Print ISBNs91-628-5514-X
Publication statusPublished - 2002
Publication categoryResearch

Bibliographic note

Defence details Date: 2003-01-17 Time: 10:30 Place: Chemical Center Sölvegatan 39, Lund, hörsal C External reviewer(s) Name: Vadgama, Pankaj Title: Prof Affiliation: Queen Mary, University of London, England --- Article: I SIRE Technology. Part II. Glucose Tolerance Monitoring, After a Peroral Intake, Employing Small Volume Whole Blood Measurements with an Amperometric BiosensorKirstin Ann Johnson and Dario KrizInstrumentation Science & Technology, 26:1 (1998) 59-67 Article: II Real-time Detection of L-Ascorbic Acid and Hydrogen Peroxide in Crude Food Samples Employing a Reversed Sequential Differential Measuring Technique of the SIRE-technology Based BiosensorKirstin Kriz, Mikeal Anderlund and Dario KrizBiosensors & Bioelectronics 16 (2001)363-369 Article: III Amperometric Determination of L-Lactate Based on Entrapment of Lactate Oxidase on a Transducer Surface with a Semi-Permeable Membrane Using a SIRE Technology Based Biosensor. Application: Tomato Paste and Baby Food.Kirstin Kriz, Linda Kraft, Margareta Krook and Dario KrizJournal of Agricultural and Food Chemistry 50 (2002) 3419-3424 Article: IV Advancements Toward Magneto ImmunoassaysKirstin Kriz, Janin Gehrke and Dario KrizBiosensors & Bioelectronics 13 (1998) 817-823 Article: V Towards a Rapid One-step Magnetic Tracer Based Heterogeneous Competitive Immunoassay for the Detection of Human Albumin in UrineKirstin Kriz, Min Lu and Dario KrizManuscript (2002)