Ultrasensitive label-free detection for lung cancer CYFRA 21-1 DNA based on ring-opening polymerization

Dual-signal amplified electrochemical biosensor based on eATRP and PEI for early detection of lung cancer

Carcinoembryonic antigen (CEA), a lung cancer marker with high sensitivity and specificity, plays vital roles in the early diagnosis of lung cancer. In this paper, an electrochemical biosensor for highly sensitive detection of CEA was constructed, which based on dual signal amplification of electrically mediated atom transfer radical polymerization (eATRP) and polyethyleneimine (PEI) for the first time. Firstly, CEA was captured in a specific recognition manner with CEA aptamer 1 (Apt1), which self-assembled on the electrode via "Au-S" bond. After that, CEA aptamer 2-PEI (Apt2-PEI) was recognized by CEA to form an Apt-antigen-Apt sandwich structure. Next, multiple initiation sites were introduced for the eATRP reaction by the amide reaction. Finally, numerous electroactive monomers, ferrocene methacrylate (FMMA), were grafted onto the modified electrode by eATRP. Under the optimized conditions, there was a wide linear detection range of 10^-3 ∼ 10² ng·mL^-1, and the limit of detection (LOD) was 70.17 fg·mL^-1. Compared to other reported sensors, this electrochemical biosensor used a simpler and more environmentally friendly eATRP, and the use of PEI increased the electron transfer rate. Moreover, the biosensor showed superior analytical performance in the clinical serums and has great promise for early lung cancer diagnosis applications.

A sandwich-type electrochemical immunosensor for CYFRA 21-1 based on probe-confined in PtPd/polydopamine/hollow carbon spheres coupled with dendritic Au@Rh nanocrystals

A signal-on sandwich-like electrochemical immunosensor was built for determination of cytokeratin 19 fragments 21-1 (CYFRA 21-1) in non-small cell lung cancer (NSCLC) by confining electroactive dye (e.g., methylene blue, MB) as a probe for amplifying signals. Specifically, core-shell gold@rhodium dendritic nanocrystals (Au@Rh DNCs) behaved as a substrate for primary antibody and accelerate interfacial electron transfer. Besides, hollow carbon spheres (HCSs) were subsequently modified with polydopamine (PDA) and PtPd nanoparticles for sequential integration of the secondary antibody and confinement of MB as a label, termed as MB/PtPd/PDA/HCSs for clarity. The built sensors showed a broad linear range (100 fg mL^-1 ~ 100 ng mL^-1) for detection of CYFRA 21-1 with an ultra-low detection limit (31.72 fg mL^-1, S/N = 3), coupled with satisfactory performance in human serum samples. This work can be explored for assays of other proteins and provides some constructive insights for early and accurate diagnosis of NSCLC.

Photoinduced atom transfer radical polymerization combined with click chemistry for highly sensitive detection of tobacco mosaic virus RNA

An electrochemical biosensor for highly sensitive detection of tobacco mosaic virus (TMV) RNA (tRNA) based on click chemistry and photoinduced atom transfer radical polymerization (photoATRP) is developed for the first time. Herein, tRNA is recognized and captured by hairpin DNA immobilized on the gold electrode surface by Au-S self-assembly. Propyl 2-bromoisobutyrate (PBIB), a photoATRP initiator containing an alkyne group, is conjugated to the azide group of hairpin DNA via a Cu(I)-catalyzed azidoalkyl cyclization reaction (CuAAC). Under the irradiation of 470 nm blue light, photoATRP is activated by the photoredox catalyst (eosin Y, EY), resulting in the formation of a large number of electroactive probes (ferrocenylmethyl methacrylate, FMMA), which significantly amplifies the signal. Under the optimal experimental parameters, the strategy has a wide linear detection (0.1 pM-10 nM) (R² = 0.995) with a limit of detection (LOD) as low as 3.5 fM. In addition, the biosensor also exhibited good selectivity for mismatched bases, excellent stability and reproducibility. Moreover, satisfactory result was achieved when the biosensor was applied to the detection of tRNA from healthy rehmannia total RNA extracts, which demonstrates the great potential of the method in the practical detection of TMV.