Supplementary Information for Schrand et al.
GNP Binding Calculations. In order to produce efficient binding, surface functionalization with ssDNA was estimated at a similar density to the number of GNPs. The calculations are summarized below for each GNP size.
1. # of ss-DNA ( 1nmole)
1nM x 10 -9 x 6.022 x 10 23 = 6.022 x 10 14
2. Density of Gold: 19.3 g/cm 3
3. Volume of each GNP a. 10nm GNP: 4/3 x 3.14 x 5 3 = 523.3 nm 3 = 5.233 x 10 -19 cm 3 b. 30nm GNP: 4/3x 3.14 x 15 3 = 1.413x10
4 nm 3 = 1.413 x 1017 cm 3 c. 60nm GNP: 4/3 x 3.14 x 30 3 = 1.13x105nm
3 = 1.13 x 10 -16 cm 3
4. Weight of each GNP a. 10nm GNP: 19.3 g/cm 3 x 5.233x10
-19 cm 3 = 1.01 x 10 -17 g = 1.01 x 10 -11 µg b. 30nm GNP: 19.3 g/cm 3 x 1.413 x 10 -17 cm 3 = 2.727 x 10 -16 g = 2.727 x 10 -10 µg c. 60nm GNP: 19.3 x 1.13x10
-16 cm 3 = 2.18 x 10 -15 g = 2.18 x 10 -9 µg
5. Number of GNP/mL (50 µg/ml) a. 10nm GNP: 50 µg/ml /1.01 x 10 -11 µg = 4.95 x 10 12 /ml d.
30nm GNP: 50 µg/ml / 2.727 x 10 -10 µg =
1.83 x 10 11 /ml e.
60nm GNP: 50 µg/ml / 2.18 x 10 -9 µg =
2.29 x 10 10 /ml

Alternatively, the calculations for ssDNA binding and GNP labeling (addition of stock
50 µg/ml concentrations) can be performed according to the equations below adapted from Teeguarden et al. (2007).
1 In this case, the number concentrations of GNP match the above calculations.
1. 10nm GNP: Concentration is 50µg/ml (10nm=1x10 -6 cm;
50 µg /ml=5x1 -5 g/ml)
Surface area Concentration = 5x10 -5 g/ml X 6/19.3g/cm 3 X 1x10 -6 cm
=15.54cm
2 /ml
# Concentration = Surface area concentration/3.14xd
2
= 15.54cm
2 /ml /3.14x1x10
-12 cm 2 = 4.95x10
12
2. 30nm GNP: Concentration is 50 µg/ml (30nm=3x10 -6 cm;
50µg /ml=5x1 -5 g/ml)
Surface area Concentration = 5x10 -5 g/ml X 6/19.3g/cm 3 X 3x10 -6 cm
=5.18 cm 2 /ml
# Concentration = Surface area concentration/3.14xd
2
= 5.18cm
2 /ml /3.14 X (3x10 -6 ) 2 cm 2 =5.18cm
2 /ml /3.14 X 9x10 -12 cm 2
= 1.83x10
11
3. 60nm GNP:
Concentration is 50 µg/ml (60nm=6x10 -6 cm; 50µg /ml=5x1 -
5 g/ml)
Surface area Concentration
5x10 -5 g/ml X 6/19.3g/cm 3 X 6x10 -6 cm=2.59cm
2 /ml
# Concentration = Surface area concentration /3.14xd
2
= 25.91cm
2 /ml /3.14 X (6x10 -6 ) 2 cm 2 =2.59cm
2 /ml /3.14 X 3.6x10
-11 cm 2
= 2.29x10
10

Visual Changes During the functionalization, capture and labeling process. Upon the addition of biofunctionalized SWNTs to the GNP solutions, the color changed from pink (Fig
S1A) to a grey hue with a pink tint remaining (Fig S1B). After mixing overnight, the samples were washed resulting in the removal of unbound GNPs and disappearance of the pink color from the 10nm and 30nm samples, but not completely from the 60nm samples (Fig S1C).
Further washing and centrifugation was not capable of completely removing 60nm GNPs from the suspension as they were either dissociating from the SWNT surface during the processing or free GNPs in the solution were centrifuged down along with the hybrid nanostructures, then becoming dispersed back into the solution upon reconstitution with water (Fig S1D).
However, final diluted solutions appeared colorless (Fig S1E).
A B C
D E
Figure S1. Digital images of representative suspensions of GNPs and hybrid SWNT-GNPs.
(A) Original GNP suspensions, (B) Suspensions immediately after the addition of dsDNA-
SWNTs, (C) Suspensions after 30 minutes of incubation with dsDNA-SWNTs, (D)
Rinsed/centrifuged hybrids and (E) Final solutions. Notice that the color of the solutions changes from light pink to grey/purple providing a visual indicator of hybridization/labeling.

Hybrid Concentration Calculations. Calculations of the concentrations of the hybrid nanostructures were based upon serial dilutions of SWNT-COOH according to previous reports.
2 In order to calculate the concentration of the hybrid particles, absorption data at
518nm was first collected on SWNT-COOH at known concentrations between 1-250 µ g/ml to generate a standard curve. Absorption data from the experimental hybrids was then collected at 518nm and correlated with the values in the standard curve according to Equation 1.
Equation 1:
Absorption = [0.0021 x Conc. ( µ g/ml)] + 0.0074
Rearranging this equation gives
Conc. ( µ g/ml) = [476.19 x Absorption] – 3.52
In this case, the hybrid concentrations ranged from 73-
110 µg/ml for the SWNT-Au hybrids with 10nm GNP hybrids demonstrating the highest concentration of 110 µg/ml followed by
60nm (82 µg/ml) and 30nm (74 µg/ml). The GNPs were strongly attached to the SWNTs via biomolecular bonding and therefore, did not display as distinct peaks with the exception of
SWNT-60nm GNPs, which had a peak at approximately 600nm (Figure S2B).

Figure S2.
Concentration calculation for hybrid SWNT-GNP nanostructures. (A) Absorption
Spectra for Hybrids (10nm, 30nm, 60nm), notice that the 60nm hybrid (circled) displays a peak suggesting inefficient attachment/suspension of 60nm GNPs and (B) Final concentration data for hybrid particles.
Control Experiments
Multiple TEM images were examined for the presence of GNP binding to either SWNT-COOH or SWNT-ssDNA (Fig S3A). No evidence for non-specific binding was found for the 10nm or
30nm GNPs. However, there was some evidence of non-specific binding of SWNT-ssDNA with 60nm GNPs (Fig S3B).
A B
Figure S3. Representative images from control experiments demonstrating (A) No binding of
10nm or 30nm GNPs to SWNT-COOH or SWNT-ssDNA and (B) Evidence of non-specific binding of SWNT-ssDNA with 60nm GNPs.
References
1 J.G.. Teeguarden, P.M. Hinderliter, G. Orr, B.D. Thrall and J.G. Pounds. Tox. Sci. 95 , 300 –
312, (2007).
2 J.P. Piret, S. Detriche, R. Vigneron, S. Vankoningsloo, S. Rolin, J.H. Mendoza-Mejia, B.
Masereel, S. Lucas, J. Delhalle, F. Luizi, C. Saout, O. Toussaint. J. Nanopart. Res. 12 , 75-82
(2010).