A newly developed optical biochip for bacteria detection based on DNA hybridization

This paper reports a bacterial optical biochip based on a developed DNA hybridization detection method using an optical measurement. Because the occurrence of bacteremia caused by Acinetobacter baumannii is high in hospitals worldwide, this species was chosen as the source of the DNA samples. Our strategy is based on a developed DNA hybridization detection method which uses probes, PCR-amplified bacterial DNA with biotin labeled primers as well as detection enhancement using gold–streptavidin nanoparticles and an Ag+–hydroquinone solution. Because the gold nanoparticles catalyze silver ions to silver metals by using hydroquinone, the gradually precipitated silver metal causes differences in the optical detection signals, which can be easily observed with the naked eye or with an optical instrument (such as a flatbed scanner). The relationships between sample concentration and detection signal are discussed, and the detection limit for Acinetobacter baumannii genomic DNA is 8.25 ng/mL (1.07 × 1010 copy/mL). Probe specificity was analyzed by detecting various species of bacteria, various strains of a single species, and various species of a single genus. The DNA hybridization detection method for the bacterial optical biochip presented in this work is easy, rapid, convenient, and promising for detecting bacterial infections and in clinical diagnoses.