Detection of gold-nanorod targeted pathogens using optical and piezoelectric optoacoustic sensors: Comparative study

摘要

We demonstrated the ability to detect surface antigens, associated with pathogens, utilizing laser optoacoustic spectroscopy with antibody-coupled gold nanorods (GNR) as a contrast agent specifically targeted to the antigen of interest. The sensitivity of the technique has been assessed by determining the minimum detectable concentration of a surface antigen from biological samples. We compared the sensitivity and applicability of two different methods for detecting optoacoustic responses, using either optical or piezoelectric sensors. Biological samples were adsorbed to the inside walls of detachable, flat-bottomed plastic micro-wells, and then probed with appropriate antibodies conjugated with gold nanorods. If the target antigens were present, the antibody-nanoparticle conjugates were bound, while any nonadsorbed nanoparticles were washed out of the wells. Optoacoustic signals were generated from the bound nanorods using a pulsed pump laser at wavelengths corresponding to one of the peak absorptions of the nanorods. Optoacoustic responses were obtained from the samples using both detection modalities. The sensitivity, suitability, ease of use of each method were assessed and compared. Initial results indicate that optical detection gives comparable sensitivity as the piezoelectric method, and further enhancement of the detection sensitivity is possible for both methods. An advantage of the piezoelectric detection method is that it may be implemented in a more compact assembly, compared to the optical method, however, the optical method may be less sensitive to external electromagnetic and acoustic noise. Further evaluation will be required to refine these measurements. The results with both methods indicate that the use of antibody-targeted nanorod contrast agents, with laser-optoacoustic detection, is a promising technology for the development of rapid in vitro diagnostic tests.