Electronic Supplementary Material

Interaction between insulin and calf thymus DNA, and quantification of insulin and calf thymus DNA by a resonance Rayleigh scattering method

Ling Kong · Zhongfang Liu · Xiaoli Hu · Shaopu Liu[(] · Wenqiang Li

Fig. s1 Fluorescence lifetime of insulin

Concentrations of insulin and ctDNA are 2.5 mg mL-1 and 5.1 mg mL-1, respectively, at pH = 7.4.

Fig. s2 Three-dimensional structure of the insulin monomer.

Fig. s3 Comparison of the absorption, fluorescence and RRS spectra of the insulin-ctDNA complex; a: absorption spectrum; b: fluorescence spectrum; c: RRS spectrum

Table s1 Stern-Volmer equations at different temperatures

T/K / Stern-Volmer equation
F0 / F =1+ksv[Q] / Correlation coefficient
(r) / Quenching constant
(ksv, L mol-1) / Binding constant
(kA, L mol-1)
295 / F0 / F =1+ 1.0×105[Q] / 0.9959 / 1.0×105 / 4.8×105
301 / F0 / F=1+ 5.7×104[Q] / 0.9951 / 5.7×104 / 1.0×103
307 / F0 / F=1+ 4.6×104[Q] / 0.9950 / 4.6×104 / 5.4×102

Table s2 Influence of exogenous substances using insulin as an RRS probe for the determination of DNA (cctDNA=2.0 mg mL-1)

Coexisting
substances / Concentration
(×10-6 mol L-1) / Change of IRRS (%) / Coexisting
substances / Concentration
(×10-6 mol L-1) / Change of IRRS (%)
Na+ / 20000 / 0.28 / Tyrosine / 25 / 4.5
Mg2+ / 100 / 1.4 / Cysteine / 50 / -2.6
Zn2+ / 10 / 1.2 / Glycine / 13000 / 3.2
Ca2+ / 2000 / -1.0 / Glucose / 550 / 4.3
Ni2+ / 10 / -3.3 / Maltose / 290 / -3.0
Cu2+ / 25 / -0.66 / BSA / 1.5* / 3.9
Al3+ / 50 / -7.1 / ATP / 300 / 2.3
Cl- / 20000 / 2.4 / AMP / 300 / 1.8
NO3- / 2000 / 3.3 / sDNA / 0.05* / 3.2
NO2- / 100 / 0.28 / hsDNA / 0.1* / 2.7
CO32- / 10 / 1.2 / CPB / 3.0 / 3.4
SO42- / 100 / 1.4 / SDS / 1.0 / 2.9
PO43- / 100 / 3.1 / Triton X-100 / 50.0 / 3.2
Phenylalanine / 100 / -4.2 / Methanol / 1.0** / 4.2
Tryptophan / 10 / -4.1 / Ethanol / 0.6** / 3.6

*Unit is mg mL-1; ** Unit is mL; CPB: cetylpyridinium bromide; SDS: sodium dodecyl sulfate

Table s3 Influence of foreign substances using ctDNA as an RRS probe for the determination of insulin (cinsulin=2.5 mg mL-1)

Coexisting substances / Concentration
(×10-6 mol L-1) / Change of IRRS (%) / Coexisting substances / Concentration
(×10-6 mol L-1) / Change of
IRRS (%)
Na+ / 20000 / 1.1 / PO43- / 100 / 4.5
Mg2+ / 40 / -2.6 / Histidine / 200 / 1.1
Zn2+ / 20 / -5 / Tryptophan / 10 / 0.6
Ca2+ / 25 / 5 / Tyrosine / 20 / -4.0
Cu2+ / 25 / 0.86 / Glucose / 400 / -1.5
Al3+ / 5.0 / -4.3 / Lactose / 500 / 3.9
Fe3+ / 0.5,2.5* / 0.63 / Maltose / 500 / 4.7
Cl- / 20000 / 4.4 / ATP / 300 / 2.3
NO3- / 800 / 0.52 / AMP / 300 / 1.8
NO2- / 100 / -0.14 / Starch / 60 / 3.2
CO32- / 10 / 1.1 / HSA / 0.050 / 3.1
SO42- / 100 / -0.14 / BSA / 0.05 / 4.4

[(] L. Kong · Z. F. Liu · X. L. Hu · S. P. Liu (*) · W. Q. Li

School of Chemistry and Chemical Engineering, Key Laboratory of Luminescence and Real-time Analysis of the Ministry of Education, Southwest University, Chongqing, China, 400715

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