Intracellular localization of nanoparticle dimers by
, Liguang Xu
, Joong Hwan Banhg
, Hua Kuang
, Silas Alben
, Nicholas A. Kotov
& Chuanlai Xu
The intra- and extracellular positioning of plasmonic nanoparticles (NPs) can dramatically
alter their curative/diagnostic abilities and medical outcomes. However, the inability of
common spectroscopic identiﬁers to register the events of transmembrane transport denies
their intracellular vs. extracellular localization even for cell cultures. Here we show that the
chiroptical activity of DNA-bridged NP dimers allows one to follow the process of inter-
nalization of the particles by the mammalian cells and to distinguish their extra- vs intra-
cellular localizations by real-time spectroscopy in ensemble. Circular dichroism peaks in the
visible range change from negative to positive during transmembrane transport. The chirality
reversal is associated with a spontaneous twisting motion around the DNA bridge caused by
the large change in electrostatic repulsion between NPs when the dimers move from inter-
stitial ﬂuid to cytosol. This ﬁnding opens the door for spectroscopic targeting of plasmonic
nanodrugs and quantitative assessment of nanoscale interactions. The efﬁcacy of dichroic
targeting of chiral nanostructures for biomedical applications is exempliﬁed here as photo-
dynamic therapy of malignancies. The efﬁcacy of cervical cancer cell elimination was dras-
tically increased when circular polarization of incident photons matched to the preferential
absorption of dimers localized inside the cancer cells, which is associated with the increased
generation of reactive oxygen species and their preferential intracellular localization.
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi , 214122, China.
International Joint Research Laboratory for Biointerface
and Biodetection, Jiangnan University, Wuxi , 214122, China.
Chemical Engineering Department, University of Michigan, Ann Arbor, MI 48109, USA.
Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
Department of Mathematics, University of Michigan, Ann
Arbor, MI 48109, USA.
Department of Material Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
Michigan Center for
Integrative Research in Critical Care, Ann Arbor, MI 48109, USA.
Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA. Maozhong Sun
and Liguang Xu contributed equally to this work. Correspondence and requests for materials should be addressed to H.K. (email: email@example.com)
or to N.A.K. (email: firstname.lastname@example.org)