Highly sensitive optical biosensor for thrombin based on structure
switching aptamer-luminescent silica nanoparticles
Ethillu Babu, Paulpandian Muthu Mareeswaran and Seenivasan Rajagopal*
a
School of Chemistry, Madurai Kamaraj University, Madurai – 625 021, India
\
*Corresponding author Tel.: +914522458246, Fax: +914522459139
E-mail: rajagopalseenivasan@yahoo.com
Supporting information
Figure S1. Synthetic scheme of [Ru(dpsphen)3]4- ion doped SiNPs labeled aptamers.
Figure S2. Absorption and emission spectra of [Ru(dpsphen)3]4- ion doped SiNPs.
Figure S3. SEM image of [Ru(dpsphen)3]4- doped silica nanoparticles. This silica nanoparticle is
prepared from the micro-heterogeneous system, the cationic surfactant is adsorbed on the surface
of silica nanoparticle resulting in the formation of micrometer scale clusters.
Element
Line
Si K
Ru K
Ru L
Ru M
Total
Net
Counts
7229
0
82
428
Net Counts
Error
+/90
0
+/18
+/21
Weight %
Atom %
Formula
95.32
--4.68
--100.00
97.95
--2.05
--100.00
Si
Ru
Quantitative Results
Figure S4. EDX spectrum of [Ru(dpsphen)3]4- ion doped silica nanoparticles. In the EDX
analysis it is possible to observe the content of various metal concentrations in this doped silica
nanoparticles. These data clearly show that the ruthenium complex is doped in to the silica
nanoparticle (2.05 % of ruthenium and 97.95 % of silica).
a)
c)
b)
d)
Figure S5. EDX color image of [Ru(dpsphen)3]4- doped silica nanoparticles a) the area of EDX
color images taken and b), c) and d) are the color image of Si, Ru1 and Ru2 content.
(magnification: 2500, accelerating Voltage: 20.0 kV). The EDX color image also shows that the
ruthenium complex is incorporated in to the silica nanoparticle( Si – green and Ru – red).
Figure S6. Stern-Volmer plot for the quenching of [Ru(dpsphen)3]4- ions doped SiNPs in the
presence of different [thrombin].
Figure S7. Spectral overlap of the absorption spectrum of DABCYL with the emission
spectrun of [Ru(dpsphen) 3]4- ion doped SiNPs.
Figure S8. Selectivity of thrombin in the presence of 0.5% BSA.
Figure S9. Schematic representation of label free sensor system for thrombin using
[Ru(dpsphen)3]4- ion doped SiNPs-aptamer comjugate.
Figure S10. Luminescence spectral changes of [Ru(dpsphen)3]4- ion doped SiNPs- aptamer
conjugate–quencher system for the detection of thrombin. The concentration of aptamer and
thrombin are 100x10-12 M, 0 - 70 x10-9 M respectively.
Figure S11. Selectivity histogram of dye doped SiNPs-aptamer conjugated system towards
thrombin. The concentration of proteins: thrombin 2.6 x 10-9 M, myoglobin 2 x 10-8 M, BSA 2 x
10-8 M, cytochrome 2 x 10-8 M, lysozyme 2 x 10-8 M, PDGF 2 x 10-8 M.