DNA nanowires-mediated high sensitive quantum dot-fluorescence-linked immunoassay for proteins analysis

Abstract

Background

Highly sensitive analysis of protein biomarkers with low concentrations is essential for biological research and medical diagnosis, where quantum dots (QDs) based fluorescence-linked immunoassay (QD-FLISA) has been given considerable attention among the quantitative detection due to its outstanding characteristics. However, the traditional QD-FLISA is usually subject to the low sensitivity owing to the limited photoluminescence (PL) intensity of QDs. In this sense, the development of novel strategy that could remarkably enhance the sensitive of traditional QD-FLISA would be highly desirable.

Results

Herein, DNA nanowires-mediated high sensitive QD-FLISA (DNA-nano-QD-FLISA) is first designed and used for the ultrasensitive detection of proteins, where DNA-nanowires are assembled through the hybridization chain reaction (HCR) and C-reactive protein (CRP) is chosen as the model analyte. The results demonstrate that the proposed DNA-nano-QD-FLISA can achieve sensitive detection of CRP, with a limit of detection (LOD) of 0.17 ng/mL, significantly lower than the system without DNA nanowires (1.66 ng/mL). Furthermore, the CRP levels in clinical samples were analyzed, yielding an excellent agreement with the Roche immunoturbidimetric method. Additionally, the versatility of the assay were demonstrated by adapting it to detect the other clinical proteins, interleukin-6 (IL-6) and procalcitonin (PCT), achieving the LODs of 0.07 ng/mL for IL-6 and 0.07 ng/mL for PCT. Furthermore, we found that the length of DNA nanowires significantly influenced the detection performance of QD-FLISA, offering a straightforward approach to precisely adjust the detection range.

Significance

This work presents an ultra-sensitive QD-FLISA for protein detection via the introduction of DNA-nanowires assembled through HCR. The achieved results demonstrate that the incorporation of DNA nanowires enhances the detection sensitivity and accuracy of traditional QD-FLISA in quantifying low-abundance biomarkers, which holds significant clinical importance for early disease screening and diagnosis.