Abstract
Rapid and quantitative prostate-specific antigen (PSA) biomarker detection would be beneficial to cancer diagnostics, improving early detection and therefore increasing chances of survival. Nanoparticle-based detection is routinely used in one-step nitrocellulose-based lateral flow (LF) immunoassays; however, it is well established within the scientific diagnostic community that LF technology lacks sensitivity for measuring biomarkers, such as prostate-specific antigen (PSA). A trend in point-of-care (POC) protein biomarker quantitation is the miniaturization of immunoassays in microfluidic devices. This work aimed at testing the feasibility of carbon and gold nanoparticles as immunoassay labels for PSA detection with cost-effective optical detection in a novel microfluidic POC platform called microcapillary film (MCF), consisting of a parallel array of fluoropolymer microcapillaries with 200-μm internal diameter. With neutravidin-coated carbon, nanoparticles were able to quantify an immobilized biotinylated monoclonal antibody (coating solution from 10 to 40 μg/ml) and PSA was successfully quantified in a sandwich assay using silver-enhanced gold nanoparticles and a flatbed scanner; yet, the dynamic range was limited to 10–100 ng/ml. Although direct optical detection of PSA without enzymatic amplification or fluorophores is possible and technically appealing for the simplified fluidics and signal scanning setups involved, ultimately, the binding of a thin layer of nanoparticles onto the wall of transparent microcapillaries is not sufficient to cause a significant drop on the optical colorimetric signal. Future studies will explore the use of fluorescence nanoparticles.
Highlights
A point-of-care (POC) test has to be sensitive, capable of detecting a broader number of clinical conditions, and the simplicity of use should approach that of a nitrocellulose lateral flow test (LF)
This paper reports for the first time the use of two different particle labels, carbon nanoparticles [25] and gold nanoparticles for optical quantitation of prostate-specific antigen (PSA) in transparent plastic microcapillary film (MCF, Fig. 1)
Carbon nanoparticles were used in LF assays for albumin detection with a limit of detection (LoD) of 0.25 μg/ml, and Kunitz-type for trypsin inhibitor was detected with a LoD of 2.5 ng/ml in competitive assay format [29]
Summary
A point-of-care (POC) test has to be sensitive, capable of detecting a broader number of clinical conditions, and the simplicity of use should approach that of a nitrocellulose lateral flow test (LF). Heterogeneous immunoassays, where the free analyte is separated from the bound forming the antibodyantigen complex, are the most sensitive bioanalytical tools used in clinical diagnostics. In most heterogeneous sandwich immunoassays, the antibody-antigen complex is quantified through label detection. The label conjugated to a detection antibody (DetAb) generates a signal which is proportional to the concentration of antigen. The nature of signal depends on the label used which in turn defines the readout system to be used. These two aspects work together establishing the overall sensitivity of the assay
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
