Absorbance enhancement in microplate wells for improved-sensitivity biosensors.
A generic optical biosensing strategy was developed that relies on the absorbance enhancement phenomenon occurring in a multiple scattering matrix. Experimentally, inserts made of glass fiber membrane were placed into microplate wells in order to significantly lengthen the trajectory of the incident light through the sample and therefore increase the corresponding absorbance. Enhancement factor was calculated by comparing the absorbance values measured for a given amount of dye with and without the absorbance-enhancing inserts in the wells. Moreover, the dilution of dye in solutions with different refractive indices (RI) clearly revealed that the enhancement factor increased with the ΔRI between the membrane and the surrounding medium, reaching a maximum value (EF>25) when the membranes were dried. On this basis, two H2O2-biosensing systems were developed based on the biofunctionalization of the glass fiber inserts either with cytochrome c or horseradish peroxidase (HRP) and the analytical performances were systematically compared with the corresponding bioassay in solution. The efficiency of the absorbance-enhancement approach was particularly clear in the case of the cytochrome c-based biosensor with a sensitivity gain of 40 folds and wider dynamic range. Therefore, the developed strategy represents a promising way to convert standard colorimetric bioassays into optical biosensors with improved sensitivity.
Institute for Work and Health, Route de la Corniche 2, CH-1066 Epalinges-Lausanne, Switzerland. Electronic address: guillaume.suarez@chuv.ch.
Guillaume
G
Suárez
Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), EPFL-STI-NAM, Station 11, CH-1015 Lausanne, Switzerland.
Christian
C
Santschi
Institute for Work and Health, Route de la Corniche 2, CH-1066 Epalinges-Lausanne, Switzerland.
Gregory
G
Plateel
Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), EPFL-STI-NAM, Station 11, CH-1015 Lausanne, Switzerland.
Olivier J F
OJ
Martin
Institute for Work and Health, Route de la Corniche 2, CH-1066 Epalinges-Lausanne, Switzerland.
Michael
M
Riediker
D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002417:Cattle; D045304:Cytochromes c / Q000737:chemistry* / Q000378:metabolism; D004800:Enzymes, Immobilized / Q000737:chemistry* / Q000378:metabolism; D005898:Glass / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000032:analysis* / Q000378:metabolism; D008958:Models, Molecular; D012031:Refractometry
D004800:Enzymes, Immobilized; C009753:fiberglass; D045304:Cytochromes c; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase
Absorbance enhancement; Hydrogen peroxide; Multiwell microplate; Optical biosensor; Random medium