title: Shell-engineered chiroplasmonic assemblies of nanoparticles for zeptomolar DNA detection.
abstract: DNA-bridged pairs of seemingly spherical metallic nanoparticles (NPs) have chiral geometry due to the nonideal oblong shape of the particles and scissor-like conformation. Here we demonstrate that deposition of gold and silver shells around the NP heterodimers enables spectral modulation of their chiroplasmonic bands in 400-600 nm region and results in significantly enhanced optical activity with g-factors reaching 1.21 × 10(-2). The multimetal heterodimers optimized for coupling with the spin angular momentum of incident photons enable polymerase chain reaction (PCR)-based DNA detection at the zeptomolar level. This significant improvement in the sensitivity of detection is attributed to improvement of base pairing in the presence of NPs, low background for chiroplasmonic detection protocol, and enhancement of photon-plasmon coupling for light with helicity matching that of the twisted geometry of the heterodimers.
authors.affiliation: State Key Lab of Food Science and Technology, School of Food Science and Technology, Jiangnan University , Wuxi, Jiangsu 214122, P. R. China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Liguang
authors.initials: L
authors.lastname: Xu
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.forename: Libing
authors.initials: L
authors.lastname: Wang
authors.forename: Hua
authors.initials: H
authors.lastname: Kuang
authors.forename: Chuanlai
authors.initials: C
authors.lastname: Xu
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Kotov
mesh_terms: D015374:Biosensing Techniques / Q000379:methods; D004247:DNA / Q000032:analysis*; D019281:Dimerization; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D016133:Polymerase Chain Reaction / Q000379:methods; D012834:Silver / Q000737:chemistry*
chemical_list: D012834:Silver; D006046:Gold; D004247:DNA