Polyethylenimine-interlayered core-shell-satellite 3D magnetic microspheres as versatile SERS substrates.
Precise fabrication of subtle nanogaps amid individual nanoparticles or between adjacent ones to obtain the highest SERS enhancement is still a challenge. Here, we reported a novel approach for fabricating core-shell-satellite 3D magnetic microspheres (CSSM), that easily form a porous 1.5 nm PEI interlayer to accommodate molecules and create sufficient hotspots between the inner Fe3O4@Ag core and outer assembled Au@Ag satellites. Experiments and finite-difference time-domain (FDTD) simulation demonstrated that the enhancement factor (EF) was about 2.03 × 10(8) and 6.25 × 10(6), respectively. In addition, the micro-scale magnetic core endowed the CSSM with a superior magnetic nature, which enabled easy separation and further enhanced Raman signals due to enrichment of targeted analytes and abundant interparticle hotspots created by magnetism-induced aggregation. Our results further demonstrated that the CSSM is expected to be a versatile SERS substrate, which has been verified by the detection of the adsorbed pesticide thiram and the non-adsorbed pesticide paraquat with a detection limit as low as 5 × 10(-12) M and 1 × 10(-10) M, respectively. The novel CSSM can overcome the long-standing limitations of SERS for the trace characterization of various analytes in different solutions and promises to transform SERS into a practical analytical technique.
Beijing Institute of Radiation Medicine, Beijing 100850, PR China. ruixiao203@sina.com sqwang@bmi.ac.cn.
Chongwen
C
Wang
Ping
P
Li
Junfeng
J
Wang
Zhen
Z
Rong
Yuanfeng
Y
Pang
Jiawen
J
Xu
Peitao
P
Dong
Rui
R
Xiao
Shengqi
S
Wang
D003287:Contrast Media / Q000737:chemistry*; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D008863:Microspheres; D011094:Polyethyleneimine / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman
D003287:Contrast Media; D012834:Silver; D011094:Polyethyleneimine; D052203:Ferrosoferric Oxide