ELECTRONIC SUPPLEMENTARY MATERIAL
T. Biver a*, A. Corti b, N. Eltugral a, E. Lorenzini b, M. Masini b, A. Paolicchi b, A. Pucci
a,c, G. Ruggeri a, F. Secco a, M. Venturini a.
Analysis of dimethylaminopyridine (DMAP)-gold nanoparticles
behaviour in solution and of their interaction with calf thymus
DNA and living cells
a Chemistry
and Industrial Chemistry Department - University of Pisa – Via
Risorgimento 35 – 56126 Pisa (Italy)
b Experimental Pathology Department BMIE - University of Pisa – Via Roma, 55 –
56126 Pisa (Italy)
c CNR NANO Nanoscience-CNR Institute, piazza S. Silvestro 12, 56127 Pisa (Italy)
T. Biver ()
e-mail: tarita@dcci.unipi.it; tel. +39-050-2219259; fax. +39-050-2219260
0.8
pH = 6.5
pH = 6
A
0.6
pH = 7
pH = 10
0.4
0.2
0.0
400
500
600
700
(nm)
Fig. 1S LS corrected absorbance spectra of aqueous dispersions of DMAP-Au NPs at different pH
values in phosphate buffer, Na2HPO4/NaH2PO4 (0.02 M/0.02 M), CAu = 1.6×10-4 M, I = 0.08 M, T
= 25 oC. The slight blue-shift from pH 10 to pH 7 indicates some NP destabilization that turns, for
pH < 6.5, in a large red-shift indicating nanoparticles aggregation.
Fig. 2S Picture of aqueous dispersions of DMAP-Au NPs at different pH values in phosphate
buffer, Na2HPO4/NaH2PO4 (0.02 M/0.02 M), CAu = 1.6×10-4 M, I = 0.08 M, T = 25 oC. Color shift
to blue indicates nanoparticles aggregation.
1.0
1.0
A
B
0.8
0.6
0.6
A
A
0.8
0.4
0.4
0.2
0.2
0.0
400
0.0
500
600
700
800
0
1

2
 C
(nm)
Au
3
4
(M)
Fig. 3S LS corrected absorbance spectra of DMAP-Au NPs at different concentrations (A) and
relevant absorbance vs. concentration plot at 520nm (B). CAu = 4.1×10-6 to 3.8×10-4 M, I = 0.08 M
(Na2HPO4/NaH2PO4 buffer), pH = 8.0, T = 25 °C.
0.4
A
0.3
0.2
0.1
0.0
200
250
300
350
400
 (nm)
Fig. 4S
UV-vis absorption spectra of the DMAP/DNA system, CDMAP = 2.0×10-5 M, CDNA =
0 – 8.2×10-5 M, pH = 8.0, T = 25 oC. Spectra invariability indicates no interaction takes place
between DMAP and DNA.
0.6
c
A
b
B
3
-1
10  A/C Au (M )
0.5
0.4
A
a
0.3
-2
0.2
2
1
0.1
0.0
400
0
500
600
(nm)
700
800
0
2
4
6

 C
DNA
8
10
(M)
Fig. 5S (A) LS corrected absorption spectra of the DMAP-Au NPs/DNA system, CAu = 1.5×10-4 M,
CDNA = 0 (a), 3.1×10-6 M (b), 9.8×10-5 M (c), pH = 8.0, T = 25 oC; (B) corresponding binding
isotherm at  = 525 nm,
Fig. 6S
Picture of DMAP-Au NPs/DNA mixtures at t = 0 (on the top) and after 72 h (at the
bottom) at the various DNA concentrations given in Table 2 (DNA concentration is zero in A and
increases until 9.8×10-5 M from B to G). Significant precipitation together with colour blue-shift is
observed in experiments B and C, whereas return to red and samples stability is observed for
experiments D to G.