Multiplexed Detection of Tumor Markers with Multicolor Polymer Dot-Based Immunochromatography Test Strip

Abstract

There have been ongoing efforts to develop more sensitive and fast quantitative screening of cancer markers by use of fluorometric immunochromatographic test strips (ICTS) since the remarkable advances in fluorescent nanomaterials. Semiconducting polymer dots (Pdots) have recently emerged as a new type of biocompatible fluorescent probe with extraordinary brightness which is suitable for biological and clinical use. Here, we developed Pdot-based ICTS for quantitative rapid screening of prostate-specific antigen (PSA), α-fetoprotein (AFP), and carcinoembryonic antigen (CEA) in 10 min. Through use of the ultrahigh fluorescence brightness of Pdots, this immunosensor enabled much better detection sensitivity (2.05, 3.30, and 4.92 pg/mL for PSA, AFP, and CEA, respectively), in which the detection limit is at least 2 orders of magnitude lower than that of conventional fluorometric ICTS. Furthermore, we performed proof-of-concept experiments for simultaneous determination of multiple tumor markers in a single test strip. These results demonstrated that this Pdot-based ICTS platform is a promising candidate for developing new generations of point-of-care diagnostics. To the best of our knowledge, this is the first example of Pdot-based ICTS with multiplexing capability.

Comparison of Semiconducting Polymer Dots and Semiconductor Quantum Dots for Smartphone-Based Fluorescence Assays

“…Surface functionality is introduced either by incorporating reactive groups into the backbone of the semiconducting polymer itself, 16,17 or, more commonly, by co-precipitation of the semiconducting polymer with amphiphilic stabilizing agents that have handles for further chemical modification. 18,19 Since their introduction in 2005, 20 Pdots have been increasingly adopted for biological assays and sensors, 15 where their high brightness has led to very promising sensitivities and detection limits, 21 including with smartphones. 22 One challenge that many Pdot materials bring with them is their broad emission spectra, which is less ideal for multiplexed detection than the spectrally-narrow emission from QDs, albeit that strategies have been developed for addressing this limitation.…”

Multiplex Lateral Flow Immunoassay: An Overview of Strategies Towards High-Throughput Point-of-Need Testing

“…They are synthesized from various carbonous precursors [51]; therefore, CQD with intrinsic chemical functionalities suitable for their conjugation to biomolecules can be obtained from appropriate precursors [52][53]. The first xLFIA exploiting CQD as the label has been described by Fang et al [54]. In their work, authors developed a fluorescence LFD for detecting three tumor markers in a single analysis, in which three lines were drawn in one strip and multicolor CQD were used as the labels to recognize the different biomarkers.…”

Machine Learning Approach to Enhance the Performance of MNP-Labeled Lateral Flow Immunoassay

“…ICTSs have been widely used for on-site testing, such as home pregnancy testing, environmental monitoring, and pathogen detection to ensure food safety [23][24][25][26][27]. However, conventional gold nanoparticle (GNP)-based ICTSs typically only provide qualitative or semiquantitative detection results with low detection sensitivity compared to traditional diagnostic methods such as the ECLIA and ELISA [23,24,28,29]. Therefore, fluorophores have been developed to replace GNPs to improve the sensitivity of ICTSs [23,30,31].…”

“…However, the fluorophores used commonly in fluorescence ICTSs, such as fluorescent dyes, are vulnerable to photobleaching [32] and are unstable at room temperature [33]. The use of quantum dots can overcome these problems because of their favorable photostability, large molar extinction coefficients, and high fluorescent quantum yield [23,[34][35][36]; however, quantum dots also face some challenges, such as chemical and colloidal instability after conjugation with specific antibodies and a high auto-fluorescence background [28,[37][38][39]. Additionally, various ICTSs based on GNPs or fluorophores can provide quantitative results by imaging the ICTSs and analyzing the colorimetric intensity of the test zone [39][40][41][42].…”