Micromechanical cantilever array sensors for selective fungal immobilization and fast growth detection

• Published in: Biosensors & bioelectronics 2005-12, Vol.21 (6), p.849-856
• Main Authors: Nugaeva, Natalia, Gfeller, Karin Y., Backmann, Natalija, Lang, Hans Peter, Düggelin, Marcel, Hegner, Martin
• Format: Article
• Language: English
• Subjects: Aspergillus niger; Aspergillus niger - growth & development; Aspergillus niger - isolation & purification; Bacterial Adhesion - physiology; Biological and medical sciences; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Biosensor; Biosensors; Biotechnology; Cell Culture Techniques - methods; Cell Proliferation; Colony Count, Microbial - instrumentation; Colony Count, Microbial - methods; Computer Systems; Electrochemistry - instrumentation; Electrochemistry - methods; Equipment Design; Equipment Failure Analysis; Fundamental and applied biological sciences. Psychology; Fungal growth measurement; Fungal spore detection; Mechanics; Methods. Procedures. Technologies; Micro-fabricated cantilever array; Microfungal selective functionalization; Miniaturization; Reproducibility of Results; Saccharomyces cerevisiae; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - isolation & purification; Sensitivity and Specificity; Spores, Fungal - growth & development; Spores, Fungal - isolation & purification; Transducers; Various methods and equipments
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2005.02.004

We demonstrate the use of micromechanical cantilever arrays for selective immobilization and fast quantitative detection of vital fungal spores. Micro-fabricated uncoated as well as gold-coated silicon cantilevers were functionalized with concanavalin A, fibronectin or immunoglobulin G. In our experiments two major morphological fungal forms were used—the mycelial form Aspergillus niger and the unicellular yeast form Saccharomyces cerevisiae, as models to explore a new method for growth detection of eukaryotic organisms using cantilever arrays. We exploited the specific biomolecular interactions of surface grafted proteins with the molecular structures on the fungal cell surface. It was found that these proteins have different affinities and efficiencies to bind the spores. Maximum spore immobilization, germination and mycelium growth was observed on the immunoglobulin G functionalized cantilever surfaces. We show that spore immobilization and germination of the mycelial fungus A. niger and yeast S. cerevisiae led to shifts in resonance frequency within a few hours as measured by dynamically operated cantilever arrays, whereas conventional techniques would require several days. The biosensor could detect the target fungi in a range of 10 3–10 6 CFU ml −1. The measured shift is proportional to the mass of single fungal spores and can be used to evaluate spore contamination levels. Applications lie in the field of medical and agricultural diagnostics, food- and water-quality monitoring.