1

Electronic Supplementary Information for the

Journal of Materials Chemistry

Corrugated and nanoporous silica microspheres: synthesis

by controlled etching, and improving their chemical

adsorption and application in biosensing

Tewodros Asefa* and Yan-Li Shi

Department of Chemistry, Syracuse University, 111 College Place,

Syracuse, NY 13244, USA

E-mail: tasefa@syr.edu;

Fax: +1-315-443-4070; Tel: +1-315-443-3360

Table S1. Pore-volume and surface area data of as-prepared and etched silica

microspheres.

Silica Nanosphere Samples Surface Area (m2/g) Pore Volume (cm3/g)

Si450 4.8 0.015

Si450-KCN-H4 5.3 0.019

Si450-KCN-H8 6.3 0.030

Si450-KOH-H4 5.5 0.040

Si450-KOH-H8 8.3 0.035

2

(A) (B) (C)

Figure S1. Enlarged TEM image of silica microspheres of average diameter of (A)

~450, (B) ~250 and (C) ~110 nm and that are labeled as Si450, Si250 and Si110,

respectively. The full images with scale bars are shown on Fig. 1 in the paper.

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(A) (B) (C)

(I)

(II)(A) (B) (C)

Figure S2. Enlarged TEM images of 100 μL, 10 mg/mL of silica microspheres of

average diameter of 450 nm (Si450) after etching with (I) 1 mL of high KCN

concentration (0.03 M, pH = 11.00) for (A) 1, (B) 4, and (C) 8 h resulting in samples

Si450-KCN-H1, Si450-KCN-H4, and Si450-KCN-H8, respectively; and (II) 1 mL of

high KOH concentration (0.03 M, pH = 12.60 for (A) 1, (B) 4, and (C) 8 h resulting

in samples Si450-KOH-H1, Si450-KOH-H4, and Si450-KOH-H8, respectively.

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FF

200 nm 100 nm

(B)(A)

Figure S3. TEM images of 100 μL, 10 mg/mL of silica microspheres of average

diameter of 450 nm (Si450) after etching for 4 h with 1 mL of low KOH concentration

(pH = 10.61), which is of the same pH as the high concentration KCN used.

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(A) (B)

(C)

Figure S4. Enlarged TEM images of 100 μL, 10 mg/mL of silica microspheres of

average diameter of 250 nm (Si250) after etching with 1 mL of higher KCN

concentration (0.03 M, pH = 11.00) for (A) 1, (B) 4, and (C) 8 h resulting in samples

Si250-KCN-H1, Si250-KCN-H4, and Si250-KCN-H8, respectively.

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200 nm 100 nm 50 nm

(C)(A)(B)

Figure S5. TEM images of 100 μL, 10 mg/mL of silica microspheres of average

diameter of 110 nm (Si110) after etching with 1 mL of higher KCN concentration (0.03

M, pH = 11.00) for (A) 4, (B) 13 and (C) 23 h under static condition.

7

428.

60

778.

44

1066

.55

1628

.36

3158

.98

1066

.27

2341

.71

2360

.4429

01.2

0

2987

.25

3422

.66

50

52

54

56

58

60

62

64

66

68

70

500 1000 1500 2000 2500 3000 3500 Wavenumbers (cm-1)

Si 450-KCN-H8Si 450-KCN-H4

Si 450Si 450-KOH-H4

air

% T

Wavenumber (cm-1)

Figure S6. FT-IR spectra of silica microspheres of average diameter of 450 nm (Si450)

before and after etching with KCN and KOH solution.