Functionalized arrays of Raman-enhancing nanoparticles for capture and culture-free analysis of bacteria in human blood
T. Y. Liu, K. T. Tsai, H. H. Wang, Y. Chen, Y. S. Chen, Y. C. Chao, H. H. Chang, C. H. Lin, J. K. Wang, Y. L. Wang*
Nat. Commun., 2, 538 (2011)
Detecting bacteria in clinical samples without using time-consuming culture processes would allow rapid diagnoses. Such a culture-free detection method requires the capture and analysis of bacteria from a body fluid, which are usually of complicated composition. Here we show that coating Ag-nanoparticle arrays with vancomycin (Van) can provide label-free analysis of bacteria via surface-enhanced Raman spectroscopy (SERS), leading to a ~1,000-fold increase in bacteria capture, without introducing significant spectral interference. Bacteria from human blood can be concentrated onto a microscopic Van-coated area while blood cells are excluded. Furthermore, a Van-coated substrate provides distinctly different SERSspectra of Van-susceptible and Van-resistant Enterococcus, indicating its potential use for drug-resistance tests. Our results represent a critical step towards the creation of SERS-based multifunctional biochips for rapid culture- and label-free detection and drug-resistant testing of microorganisms in clinical samples.