Colorimetric and Fluorescent Dual-Mode Immunoassay Based on Plasmon-Enhanced Fluorescence of Polymer Dots for Detection of PSA in Whole Blood

Abstract

Although enormous efforts have been devoted to the development of new types of fluorometric immunochromatographic test strip (ICTS) with improved sensitivity over the past years, it still remains a big challenge to design ICTS with colorimetric and fluorescent bimodal signal readout for rapid yet accurate detection of cancer markers in a clinic. Scientists have tried to prepare bimodal reporters by combining fluorescent dyes with metal nanomaterials, but their fluorescence was easily quenched by metal nanomaterials through surface energy transfer, making dual colorimetric and fluorometric ICTS very difficult to be achieved. As compared to conventional fluorescent probes, semiconducting polymer dots (Pdots) exhibit extraordinary fluorescence brightness and facile surface functionalization, which are very suitable to be engineered as bimodal signal reporting reagents. Here, we integrated highly fluorescent Pdots with strongly plasmonic Au nanorods to form Pdot–Au hybrid nanocomposites with dual colorimetric and fluorescent readout abilities. We further utilized these nanohybrids in ICTS for qualitatively fast screening (colorimetry) as well as quantitatively accurate determination (fluorometry) of prostate-specific antigen (PSA) within 10 min. By taking advantage of the plasmon-enhanced fluorescence of Pdots on Au nanorods, this immunoassay possesses much better detection sensitivity of 1.07 pg/mL for PSA, which is at least 2 orders of magnitude lower than that of conventional fluorometric ICTS. Moreover, the direct detection of PSA from human whole blood collected without sample pretreatment makes this Pdot-based ICTS platform promising for on-site point-of-care diagnostics.

Compact Magneto‐Fluorescent Colloids by Hierarchical Assembly of Dual‐Components in Radial Channels for Sensitive Point‐of‐Care Immunoassay

“…Therefore, the SIQS‐based LFIA provides flexible dual‐modal signal readouts for personalized quantification scenarios and the potential for self‐validating to exclude background interferences. [ 62–65 ] Compared with previous reports for PCT detection, the SIQS‐based LFIA exhibits high sensitivity and relatively short detection time (Table S2, Supporting Information), [ 66–73 ] demonstrating the potential of the proposed assay for POC detecting of PCT.…”

Recent Advances in Novel Lateral Flow Technologies for Detection of COVID-19

“…Many QD-based LFIAs have been developed to achieve ultrasensitive detection [ 62 , 103 , 104 , 105 ]. In a recent study, Wang et al reported a dual-mode LFIA for SARS-CoV-2 IgM/IgG detection based on QD nanobeads ( Figure 7 ) [ 63 ].…”

Sensitive and Simultaneous Detection of SARS-CoV-2-Specific IgM/IgG Using Lateral Flow Immunoassay Based on Dual-Mode Quantum Dot Nanobeads

“…In recent years, quantum dots (QDs) are widely used as fluorescence labels in the LFIA system to improve sensitivity and quantitative ability because of their excellent optical properties, including quantifiable fluorescence intensity, broad excitation, and high light stability. 15 − 17 Nevertheless, a large-scale application of QD-based LFIA strip remains limited because common QDs are too small (5–20 nm) to centrifuge and are unstable for chemical modification. Additionally, a QD-based LFIA requires an additional UV light source or a commercial fluorescent reader for fluorescence signal measurement, which may be a burden for areas with poor medical conditions.…”