Highly sensitive fluorescence detection of tobacco mosaic virus RNA based on polysaccharide and ARGET ATRP double signal amplification.

Plant diseases caused by tobacco mosaic viruses (TMV) reduce the yield and quality of crops and cause significant losses. Early detection and prevention of TMV has important value of research and reality. Herein, a fluorescent biosensor was constructed for highly sensitive detection of TMV RNA (tRNA) based on the principle of base complementary pairing, polysaccharides and atom transfer radical polymerization by electron transfer activated regeneration catalysts (ARGET ATRP) as double signal amplification strategy. The 5'-end sulfhydrylated hairpin capture probe (hDNA) was first immobilized on amino magnetic beads (MBs) by a cross-linking agent, which specifically recognizes tRNA. Then, chitosan binds to BIBB, providing numerous active sites for fluorescent monomer polymerization, which successfully significantly amplifying the fluorescent signal. Under optimal experimental conditions, the proposed fluorescent biosensor for the detection of tRNA has a wide detection range from 0.1 pM to 10 nM (R2 = 0.998) with a limit of detection (LOD) as low as 1.14 fM. In addition, the fluorescent biosensor showed satisfactory applicability for the qualitative and quantitative analysis of tRNA in real samples, thereby demonstrating the potential in the field of viral RNA detection.

Electrochemical immunosensor for highly sensitive detection of cTnI via in-situ initiated ROP signal amplification strategy.

Cardiac troponin I (cTnI) is considered to be the most valuable biomarker for the diagnosis of acute myocardial infarction (AMI). The sensitive and efficient determination of cTnI is essential for the early diagnosis and prognostic assessment of AMI. In this paper, we designed for the first time an electrochemical immunosensor based on the ring-opening polymerization (ROP) reaction as a signal amplification strategy for the highly sensitive detection of cTnI. Briefly, 3-mercaptopropionic acid (MPA) was used as a cross-linking agent to immobilize Ab1 on the surface of gold electrodes, and subsequently Ab1 specifically captured cTnI. Then, the glycolic acid-coupled cTnI-secondary antibody (GA-Ab2) bound specifically to cTnI to form a sandwich structure and provided the initiation site for the subsequent polymerization reaction. Subsequently, ferrocene formyloxyate propylene oxide (FFAPO) was used as the monomer and large quantities of electroactive polymers were grafted to the electrode surface via a hydroxyl-initiated ROP reaction, which significantly amplified the electrochemical signal. Under optimal conditions, the immunosensor displayed good linearity in the concentration range of 1 pg mL-1-1 µg mL-1 and the limit of detection down to 57.14 fg mL-1, which was superior to most of those reported assays. Compared to other signal amplification strategies, this ROP reaction showed relatively easy access to raw materials and comparatively mild reaction conditions. In addition, the results of the serum sample detection capability indicated that the immunosensor exhibited excellent detection selectivity and reliability in serum. Thus, owing to its good selectivity, high sensitivity and excellent stability, the immunosensor shows great potential for clinical application.