Label free point mutation detection is particularly momentous in the area of biomedical research and clinical diagnosis since gene mutations naturally occur and bring about highly fatal diseases. In this paper, a label free and high sensitive approach is proposed for point mutation detection based on hyperspectral interferometry. A hybridization strategy is designed to discriminate a single-base substitution with sequence-specific DNA ligase. Double-strand structures will take place only if added oligonucleotides are perfectly paired to the probe sequence. The proposed approach takes full use of the inherent conformation of double-strand DNA molecules on the substrate and a spectrum analysis method is established to point out the sub-nanoscale thickness variation, which benefits to high sensitive mutation detection. The limit of detection reach 4pg/mm2 according to the experimental result. A lung cancer gene point mutation was demonstrated, proving the high selectivity and multiplex analysis capability of the proposed biosensor.
Optical microscopy technology has achieved great improvements in the 20th century. The detection limit has reached about twenty nanometers (with near-field optics, STED, PALM and STORM). But in the application areas such as life science, medical science, clinical treatment and especially in vivo dynamic measurement, mutual restrictions still exist between numeric aperture/magnification and working distance, fluorescent dependent, and between resolution and frame rate/field size, etc. This paper explores a hyperspectral scanning super-resolution label free molecules imaging method based on the white light interferometry. The vertical detection resolution was approximate to 1 nm which is the thickness of a single molecular layer and dynamic measuring range of thickness reaches to 10 μm. The spectrum-shifting algorithm is developed for robust restructure of images when the pixels are overlapped. Micro-biochip with protein binding and DNA amplification could be detected by using this spectral scanning super-resolution molecules imaging in label free. This method has several advantages as following: Firstly, the decoding and detecting steps are combined into one step. It makes tests faster and easier. Secondly, we used thickness-coded, minimized chips instead of a large microarray chip to carry the probes. This accelerates the interaction of the biomolecules. Thirdly, since only one kind of probes are attached to our thickness-coded, minimized chip, users can only pick out the probes they are interested in for a test without wasting unnecessary probes and chips.