Label-free detection of single-nucleotide polymorphisms associated with myeloid differentiation-2 using a nanostructured biosensor.

House dust mites are the major source of indoor allergens that are responsible for asthma. The major dust mite allergen is the group II allergen, Der p2. Myeloid differentiation-2 (MD-2) acts as an essential component in the CD14-TLR4 (toll-like receptor)/MD-2 receptor complex for Der p2 recognition. Mutations of the MD-2 associated gene on chromosome 8 degrade a human's innate responses. In this study, we report the effective detection of mutations to the MD-2 gene promoter, using a sensitive nanostructured biosensor with a sensing electrode of gold nanoparticles (GNPs) uniformly deposited in a nanohemisphere array. The 70 mer MD-2 expressed gene fragment was used to probe gene mutation. The complementary target, containing 156 mer nucleotide, was prepared using the fresh blood from patients with allergic disease. A total of 37 target samples, including 19 gene mutated samples and 18 normal samples, were prepared by a 20 cycles PCR process, and used for discrimination experiments. Experimental results illustrated that the nanostructured biosensor clearly discriminates between mutated and non-mutated MD-2 allergy genes.