Label-free, sensitive Streptomycete spore detection by silver-plated photonic crystals biosensor

Highly sensitive bacteria identification plays an important role in the field of clinical diagnosis, food industry, and environmental monitoring. Common techniques for identification of Streptomyces include polymerase chain... [ view full abstract ]

Highly sensitive bacteria identification plays an important role in the field of clinical diagnosis, food industry, and environmental monitoring. Common techniques for identification of Streptomyces include polymerase chain reaction (PCR) and staining method, which have been developed for decades. However, PCR method is time-consuming and needs following procedures like electrophoresis, gene sequencing and sequence alignment. Staining method based on Gram staining is highly dependent on the concentration and purity of samples. In this paper, a label-free, sensitive biosensor based on silver-plated photonic crystal (PC) was developed both for the filtration and identification of spores from nosiheptide prepared with Streptomycete fermentation through Surface-enhanced Raman Scattering (SERS). The Finite difference time domain (FDTD) results indicated that this biosensor exhibited good electric field enhancement which contributes to the Raman intensity. A “drop and measure” manner was adopted for the spore identification with only 5 μl sample and 5 minutes. The Raman results showed that this label-free biosensor could be not only utilized for the highly sensitive spore identification from nosiheptide prepared with Streptomycete fermentation, but also applied to the discrimination of nosiheptide prepared with chemical and biological methods. The label-free, sensitive silver-plated PC biosensor will be a promising tool for the highly sensitive bacteria and chemical molecule detection in food safety, environmental and pharmaceutical applications.