We have recently investigated a new generation of biosensors using DNA probes (DNA Biochip). Probe recognition is based on the molecular hybridization process, which involves the joining of a strand of nucleic acid with a complementary sequence. Biologically active DNA probes are directly immobilized on optical transducers which allow detection of Raman, SERS, or fluorescent probe labels. DNA biosensors could have useful applications in areas where nucleic acid identification is involved. The DNA probes could be used to diagnose genetic susceptibility and diseases. The Biochip using antibody probes has recently been developed to detect the p53 protein system
Plasmonic SERS Nanobiosensors for Point-of-Care Molecular Diagnosis and Global Health Applications
Nucleic acid-based molecular diagnosis is of paramount importance in medicine, biosensing, forensic science, etc. with many advantages such as high specificity, high sensitivity, serotyping capability, and mutation detection. Currently, the gold standard of nucleic acid-based molecular diagnostics tests involves polymerase chain reaction (PCR), which is highly sensitive but also quite expensive, time-consuming, labor-intensive, and prone to contaminations. Using plasmonic nanobiosensors and surface-enhanced Raman scattering, we are developing novel nucleic acid detection methods that can be integrated into lab-on-a-chip systems for point-of-care diagnosis and global health applications.
Figure 1. When complementary target ssDNA targets are introduced, they hybridize with the placeholders, and the reporter probes are free to form hairpin structures due to their design. With hairpin structures, Raman dyes are brought into close proximity of Nanowave chip’s metal surface, inducing strong SERS signals .
Figure 2. (a) The nanorattle-based DNA detection method using sandwich hybridization of (1) magnetic bead that are loaded with capture probes, (2) target sequence, and (3) ultrabright SERS nanorattles that are loaded with reporter probes. (b) A magnet is applied to concentrate the hybridization sandwiches at a detection spot for SERS measurements .
 HT Ngo, HN Wang, AM Fales, BP Nicholson, CW Woods, T Vo-Dinh, “DNA bioassay-on-chip using SERS detection for dengue diagnosis”, Analyst 139 (22), 5656-5660, 2014
 HT Ngo, N Gandra, AM Fales, SM Taylor, T Vo-Dinh, “Sensitive DNA detection and SNP discrimination using ultrabright SERS nanorattles and magnetic beads for malaria diagnostics”, Biosensors and Bioelectronics, 81, 8–14, 2016