title: Attomolar detection of proteins via cascade strand-displacement amplification and polystyrene nanoparticle enhancement in fluorescence polarization aptasensors.
abstract: Extremely sensitive and accurate measurements of protein markers for early detection and monitoring of diseases pose a formidable challenge. Herein, we develop a new type of amplified fluorescence polarization (FP) aptasensor based on allostery-triggered cascade strand-displacement amplification (CSDA) and polystyrene nanoparticle (PS NP) enhancement for ultrasensitive detection of proteins. The assay system consists of a fluorescent dye-labeled aptamer hairpin probe and a PS NP-modified DNA duplex (assistant DNA/trigger DNA duplex) probe with a single-stranded part and DNA polymerase. Two probes coexist stably in the absence of target, and the dye exhibits relatively low FP background. Upon recognition and binding with a target protein, the stem of the aptamer hairpin probe is opened, after which the opened hairpin probe hybridizes with the single-stranded part in the PS NP-modified DNA duplex probe and triggers the CSDA reaction through the polymerase-catalyzed recycling of both target protein and trigger DNA. Throughout this CSDA process, numerous massive dyes are assembled onto PS NPs, which results in a substantial FP increase that provides a readout signal for the amplified sensing process. Our newly proposed amplified FP aptasensor enables the quantitative measurement of proteins with the detection limit in attomolar range, which is about 6 orders of magnitude lower than that of traditional homogeneous aptasensors. Moreover, this sensing method also exhibits high specificity for target proteins and can be performed in homogeneous solutions. In addition, the suitability of this method for the quantification of target protein in biological samples has also been shown. Considering these distinct advantages, the proposed sensing method can be expected to provide an ultrasensitive platform for the analysis of various types of target molecules.
authors.affiliation: Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education), College of Chemistry and Pharmacy, Guangxi Normal University, Guilin 541004, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education), College of Chemistry and Pharmacy, Guangxi Normal University, Guilin 541004, China.
authors.forename: Xiaoqian
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education), College of Chemistry and Pharmacy, Guangxi Normal University, Guilin 541004, China.
authors.forename: Huakui
authors.initials: H
authors.lastname: Huang
authors.affiliation: Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education), College of Chemistry and Pharmacy, Guangxi Normal University, Guilin 541004, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Qin
authors.affiliation: Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education), College of Chemistry and Pharmacy, Guangxi Normal University, Guilin 541004, China.
authors.forename: Liangliang
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education), College of Chemistry and Pharmacy, Guangxi Normal University, Guilin 541004, China.
authors.forename: Shulin
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education), College of Chemistry and Pharmacy, Guangxi Normal University, Guilin 541004, China.
authors.forename: Zhen-Feng
authors.initials: ZF
authors.lastname: Chen
authors.affiliation: Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education), College of Chemistry and Pharmacy, Guangxi Normal University, Guilin 541004, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Liang
mesh_terms: D052157:Aptamers, Nucleotide / Q000032:analysis* / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D004591:Electrophoresis, Polyacrylamide Gel; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D053758:Nanoparticles / Q000737:chemistry*; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D011137:Polystyrenes / Q000737:chemistry*; D011506:Proteins / Q000032:analysis*; D013917:Thrombin / Q000032:analysis
chemical_list: D052157:Aptamers, Nucleotide; D005456:Fluorescent Dyes; D011137:Polystyrenes; D011506:Proteins; D013917:Thrombin