Characterization of the interactions between tetracycline antibiotics and microbial extracellular polymeric substances with spectroscopic approaches

Chao Song, Xue-Fei Sun*, Su-Fang Xing,Peng-Fei Xia,Yi-Jing Shi, Shu-Guang Wang

Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China

Number of page = 15

Equation list

Figure S1

Figure S2

Figure S3

Figure S4

Figure S5

Figure S6

Figure S7

Table S1

Table S2

Table S3

Equation list

Dynamic quenching Stern-Volmer equation

F0 thefluorescence intensity in absence of the quencher

F thefluorescence intensity in presence of the quencher

Ksv the dynamic quenching constant（L mol-1）

[Q] the concentration of quencher (mol L-1)

Kq the quenching rate constant(L mol-1S-1)

0 the average lifetime of the molecule without any quencher 10-8s

Static quenching Modified Stern-Volmer equation

Ka the static quenching constant (mol L-1)

fa the fraction of accessible fluorescence

Van’t Hoff equation

K analogous to the quenching constants Ka at the corresponding temperature

R the gas constant 8.314 J K-1 mol-1

T the temperature (K)

the enthalpy change (kJ mol-1)

S the entropy change (J mol-1K-1)

Thermodynamic equation

G the Gibbs free energy change (kJ mol-1)

Kb the binding constant (L mol-1)

n the number of binding sites

Figure captions:

Fig.S1

Fig.S1a: FTIR spectra of (I) the pristine and (II) TC-treated sodium alginate

Fig.S1b: FTIR spectra of (I) the pristine and (II) TC-treated BSA

Fig.S2

Fig.S2a: XPS spectra of (I, III, V) the pristine and (II, IV, VI) TC-treated sodium alginate

Fig.S2b: XPS spectra of (I, III, V) the pristine and (II, IV, VI) TC-treated BSA

Fig.S3

Fig.S3a:1H NMR spectrum of (I) the pristine sodium alginate; (II) TC-treated sodium alginate; (III) TC

Fig.S3b:1H NMR spectrum of (I) the pristine BSA; (II) TC-treated BSA; (III) TC

Fig.S4 Stern-Volmerplots for the interaction of EPS and tetracyclineat different temperatures.

Fig.S5DifferentiatedUV-visible absorption spectra of EPS (solid line)and EPS-TC complex (dot line) at various TC dosages. From a toe, the TC concentration is 10, 20, 30, 40, 50 μmol L-1. The spectra of TC at the same dosage had been subtracted from the spectra of EPS-TC complex.

Fig.S6 Stern-Volmer plots for dynamic quenching of EPS by tetracycline

Fig.S7 Stern-Volmer plots for the interaction of BSA and tetracycline at different temperatures.

Fig.S1

Fig.S2

Fig.S3

Fig.S4

Fig.S5

Fig.S6

Fig.S7

Table S1 Binding energies (eV),assignments, and quantization of XPS spectral bands of the pristine and TC-treated EPS

Element / EPS / TC-treated EPS / Assignments
peak (eV) / atomic (%) / peak (eV) / atomic (%)
C 1s / 284.30 / 33.06 / 284.46 / 36.88 / C-(C,H)
C 1s / 285.11 / 39.46 / 286.08 / 46.64 / C-(O,N)
C 1s / 287.69 / 21.54 / 288.05 / 16.48 / C=O,O-C-O
C 1s / 289.15 / 5.94 / HO-C=O,RO-C=O
O 1s / 530.46 / 51.80 / 531.25 / 47.41 / C=O
O1s / 531.84 / 48.20 / 532.45 / 52.59 / C-O-C,C-O-H
N 1s / 399.22 / 97.40 / 399.42 / 72.64 / nonprotonated nitrogen
N 1s / 401.4 / 2.60 / 401.60 / 27.36 / protonated nitrogen

Table S2 Dynamic quenching constants for interaction of EPS with TC at different temperature

T / Ksv（105L mol-1） / Kq（1013L mol-1S-1） / R2 / S.D
298K / 1.08 / 1.08 / 0.9104 / 0.138
308K / 1.13 / 1.13 / 0.9505 / 0.104

Table S3 Parameters of Stern-Volmer equation and Van't Hoff equation for interaction of BSA with tetracycline at different temperature

T / Kaa（105mol L-1） / H（KJ mol-1） / S（J mol-1K-1） / G（KJ mol-1） / Kbb（108mol L-1） / nc
298K / 5.53 / -25.22 / 6.16 / -27.05 / 0.87 / 1.69
308K / 3.98 / 6.17 / -27.12 / 1.01 / 1.68

a the fluorescence quenching constant

b binding constant

c the number of binding sites

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Corresponding author. Tel.: +86 531 88362802; fax: +86 531 88364513.

E-mail address: (Shu-Guang Wang), (Xue-Fei Sun)