Interferometric silicon biochips for label and label‐free DNA and protein microarrays

Abstract

Protein and DNA microarrays hold the promise to revolutionize the field of molecular diagnostics. Traditional microarray applications employ labeled detection strategies based on the use of fluorescent and chemiluminescent secondary antibodies. However, the development of high throughput, sensitive, label-free detection techniques is attracting attention as they do not require labeled reactants and provide quantitative information on binding kinetics. In this article, we will provide an overview of the recent author's work in label and label-free sensing platforms employing silicon/silicon oxide (Si/SiO(2)) substrates for interferometric and/or fluorescence detection of microarrays. The review will focus on applications of Si/SiO(2) with controlled oxide layers to (i) enhance the fluorescence intensity by optical interferences, (ii) quantify with sub-nanometer accuracy the axial locations of fluorophore-labeled probes tethered to the surface, and (iii) detect protein-protein interactions label free. Different methods of biofunctionalization of the sensing surface will be discussed. In particular, organosilanization reactions for monodimensional coatings and polymeric coatings will be extensively reviewed. Finally, the importance of calibration of protein microarrays through the dual use of labeled and label-free detection schemes on the same chip will be illustrated.

Interferometric Reflectance Imaging Sensor (IRIS)—A Platform Technology for Multiplexed Diagnostics and Digital Detection

“…It has been shown that Si chips are compatible with fluorescence assays and they provide considerable advantages by enhancing the fluorescence signal [ 22 ], thus allowing for a pre-calibration and quality control by IRIS. In light of these advantages, the utility of a calibrated fluorescence enhancement (CaFE) method has been demonstrated in [ 14 , 15 , 23 ] on an integrated platform. Significant improvements have been demonstrated for a particular application involving allergen-specific IgE detection with two major allergens, peanut (Ara h1) and timothy grass (Phl p1), whose immobilization can vary significantly making fluorescence signal calibration vital to obtain accurate results [ 17 ].…”

Membrane‐binding peptides for extracellular vesicles on‐chip analysis

“…Probe density for each immobilised peptide on the array was assessed using label-free film thickness measurement using on the Nanoview platform by nanoQC2.3.2-IT software (NanoView Biosciences, Boston, MA) and previously determined calibration factors for IRIS [43,44]. The average amount of each immobilised peptide was 1.5-3.5 ng/mm 2 .…”

Performance of a polymer coated silicon microarray for simultaneous detection of food allergen‐specific IgE and IgG4

“…With the introduction of a silicon/silicon oxide (Si/SiO 2 ) substrate, coated with the functional polymer copoly(DMA‐NAS‐MAPS), we have provided a highly sensitive microarray platform with better reproducibility compared to glass slides whose performance was demonstrated in the analysis of sera of 30 adults with sensitization to inhalant allergens . The improved performance of Si/SiO 2 slides with a controlled oxide layer of 100 nm is the result of enhanced fluorescence intensity detected on the surface thanks to constructive optical interference …”