title: Carbon nanotubes multifunctionalized by rolling circle amplification and their application for highly sensitive detection of cancer markers.
abstract: There are still challenges for the development of multifunctional carbon nanotubes (CNTs). Here, a multiwalled carbon nanotube (MWCNT)-based rolling circle amplification system (CRCAS) is reported which allows in situ rolling circle replication of DNA primer on the surface of MWCNTs to create a long single-strand DNA (ssDNA) where a large number of nanoparticles or proteins could be loaded, forming a nano-biohybridized 3D structure with a powerful signal amplification ability. In this strategy, the binding ability of proteins, hybridization, replication ability of DNA, and the catalytical ability of enzymes are integrated on a single carbon nanotube. The CRCAS is then used to develop colorimetric and chemiluminescent assays for the highly sensitive and specific detection of cancer protein markers, alpha-fetoprotein (AFP) and prostate specific antigen (PSA). The colorimetric CRCAS assay is 4000 times more sensitive than a conventional enzyme-linked immunosorbent assay (ELISA), and its concentration range is 10,000 times wider. Control experiments show that as low as 10 pg mL⁻¹ AFP or PSA could be detected even in the presence of interfering protein markers with a more than 10⁵-fold greater concentration in the sample, demonstrating the high specificity of the CRCAS assay. The limit of detection of the chemiluminescent CRCAS assays for AFP and PSA are 5 fg mL⁻¹ (70 aM) and 10 fg mL⁻¹ (0.29 fM), respectively, indicating that the sensitivity is much higher than that of the colorimetric CRCAS assay. Importantly, CRCAS works well with real biological samples.
authors.affiliation: Laboratory of Physical Biology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhao
authors.forename: Juan
authors.initials: J
authors.lastname: Yan
authors.forename: Dongfang
authors.initials: D
authors.lastname: Wang
authors.forename: Zhilei
authors.initials: Z
authors.lastname: Ge
authors.forename: Shijiang
authors.initials: S
authors.lastname: He
authors.forename: Dannong
authors.initials: D
authors.lastname: He
authors.forename: Shiping
authors.initials: S
authors.lastname: Song
authors.forename: Chunhai
authors.initials: C
authors.lastname: Fan
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D001826:Body Fluids / Q000378:metabolism; D003124:Colorimetry; D006046:Gold / Q000737:chemistry; D006801:Humans; D008163:Luminescent Measurements; D053768:Metal Nanoparticles / Q000648:ultrastructure; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D016133:Polymerase Chain Reaction / Q000379:methods*; D019809:Streptavidin / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D037742:Nanotubes, Carbon; D006046:Gold; D019809:Streptavidin
keywords: cancer markers; carbon nanotubes; detection systems; enzymes; rolling circle amplification