Ultrasensitive Fluorescence Polarization Aptasensors Based on Exonuclease Signal Amplification and Polystyrene Nanoparticle Amplification

Abstract

Here, we combine T7 exonuclease (T7 Exo) signal amplification and polystyrene nanoparticle (PS NP) amplification to develop novel fluorescence polarization (FP) aptasensors. The binding of a target/open aptamer hairpin complex or a target/single-stranded aptamer complex to dye-labeled DNA bound to PS NPs, or the self-assembly of two aptamer subunits (one of them labeled with a dye) into a target/aptamer complex on PS NPs leads to the cyclic T7 Exo-catalyzed digestion of the dye-labeled DNA or the dye-labeled aptamer subunit. This results in a substantial decrease in the FP value for the amplified sensing process. Our newly developed aptasensors exhibit a sensitivity five orders of magnitude higher than that of traditional homogeneous aptasensors and a high specificity for the target molecules. These distinct advantages of our proposed assay protocol make it a generic platform for the design of amplified aptasensors for ultrasensitive detection of various target molecules.

Recent progress in nanomaterial-enhanced fluorescence polarization/anisotropy sensors

“…Recently, a number of nanomaterial, such as carbon nanoparticles (CNPs), gold nanoparticals (AuNPs), metal-organic frameworks (MOFs), SiO2 nanoparticals (SiO2 NPs), graphene oxide (GO), quantum dots (QDs), carbon nanotubes (CNTs), 2D transition metal dichalcogenide nanosheets (TMD NSs), MnO2 nanosheets were introduced into FP/FA sensor system, has brought revolutionary effect for greatly improving detection sensitivity and application range of FP/FA, due to its unique structure and extraordinary properties such as simple/controllable synthesis and modification, different sizes, large volumes and masses, chemical compositions and morphologies, excellent optical and chemical properties [26][27][28][29][30][31][40][41][42][43][44]. Table 1 lists various targets of interest, FP/FA enhancer and signal amplification methods, analytical performance, and so on [40][41][42][43][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60].…”

AIEgens/Nucleic Acid Nanostructures for Bioanalytical Applications

“…DNA can be extended to longer chains by means of enzyme‐catalyzed reactions . DNA is also biodegradable owing to the existence of nucleases . These AIEgens‐functionalized DNA probes are stabilized by means of a variety of noncovalent interactions, such as aromatic, van der Waals, and hydrogen‐bonding interactions between nucleobases and electrostatic interactions with the negatively charged phosphate backbone.…”

“…[17,18] DNA is also biodegradableo wing to the existence of nucleases. [19,20] These AIEgens-functionalized DNA probes are stabilized by meanso fa variety of noncovalenti nteractions,s uch as aromatic, van der Waals, and hydrogen-bonding interactions between nucleobases and electrostatic interactions with the negatively charged phosphate backbone. The molecular mechanismsu nderlying the target-induced enhancement of the fluorescences ignal of the light-upA IEgensa re due to the restrictiono fi ntramolecular rotation(RIR).…”

Multifunctional aggregates for precise cellular analysis

“…Next, nucleic acids store the life genetic information [8][9][10][11]. Nucleic acids with specific sequences have the capabilities to efficiently recognize bio-targets, including small molecules, nucleic acid strands and biomacromolecules by hybridizing with the targeted oligonucleotide, changing the conformation, and elongating the chain [10,12,13]. Then, aggregation elements in this article refer to hydrophobic molecules with aggregation-induced emission (AIE) feature.…”