Chromogen-free color interference-based biosensors for visual detection of viruses

An optical biosensor is a miniature analytical device. It converts the information about an analyte in a complex sample into the analytical signal in real time.   Such sensors provide non-destructive analysis and at the same... [ view full abstract ]

An optical biosensor is a miniature analytical device. It converts the information about an analyte in a complex sample into the analytical signal in real time.   Such sensors provide non-destructive analysis and at the same time can be miniaturized down to nanometer-size that is why they became perspective instrument of quantitative microanalysis. 

Here we demonstrate, new conception for simple visual detection of bio-analytes in solutions. Towards the achievement of that goal we describe the strong interference in sol-gel titania films which change a color after interaction with virus-like structures and show that the developed approach can also be used for qualitative and quantitative analyses even with naked eye.

Figure1. Schematic illustration of interference in thin films, where R — incident light beam; R^* — light beam reflected from interface; I — combination of reflected beams (coloring effect). Calibration curve, average analytical signal as a function of bacteriophage concentration.

We show theoretically and experimentally how interference in thin films can be used as analytical signal for optical sensors. Due to inkjet printing the sensor substrates present good reproducibility, which makes it possible to scale the production for integrating into the industrial manufacturing process.  Analytical applicability was approved on the Staphylococcus aureus bacteriophage. Due to specificity of interference optical signal, two new methods of experimental data interpretation were proposed. It is expected that presented optical sensor system will allow to conduct several analyses simultaneously in one sample, particularly by applying multiple antibodies on different sections of a sensor array.