Rifamycin

Fetal bovine serum (FBS) and an antibiotic-antimycotic
solution (100×) were purchased from the GIBCO (GIBCO, BRL, Inchinnman
UK). Escort IV reagent, Dithiothreitol (DTT), anti-Rabbit-IgG-cy-3,
Hoechst 33258, TRI-Reagent, testosterone, dihydrotestosterone (DHT),
β-estradiol, and flutamide were purchased from Sigma-Aldrich
(St. Louis, MO, USA). Hydrocortisone, MTT (3-(4,5-dimethyl-2-thiazolyl)
2,5diphenyl-2H-tetrazolium bromide), and cell culture media were purchased
from Himedia (Mumbai India). DNaseI was purchased from NEB, England.
Oxytetracyclin (catalog number-75966), chloramphenicol (catalog number-C0378),
oxacillin (catalog number-28221), streptomycin (catalog number-S6501),
tetracyclin (catalog number-T3258), rifamycin (catalog number-R3501),
ciprofloxacin (catalog number-17850), rotenone (catalog number-R8875),
and BPA (catalog number-239658) purchased from Sigma-Aldrich (St.
Louis, MO, USA) were a kind gift from Prof. S. P. Singh, Banaras Hindu
University, Varanasi, India.

Agilent Cary Eclipse fluorescence spectrophotometer was used for the ensemble fluorescence experiments. A 530 nm wavelength (10 nm window) excitation was used for the Cy3–Cy5 FRET pair on the aptamer and emission spectra were collected for 550–800 nm. All experiments were conducted with 2 nM KBA_FRET at room temperature when not listed otherwise. Kanamycin (Sigma Aldrich), and other antibiotics such as streptomycin, chloramphenicol, ethambutol, ampicillin, penicillin (P)–streptomycin, tetracycline and rifamycin (Sigma Aldrich) were used at the concentrations indicated in Fig. 2B. 1× KBA buffer (50 mM Tris–HCl, 10 mM NaCl, pH 7.4) was used in all the experiments unless mentioned otherwise. For evaluating the performance of KBA_FRET in presence of milk sample, we pre-treated the milk with 20% acetic acid to adjust the pH to 4.6, followed by incubation for 10 min at 45 °C. The curdled milk particles were removed by centrifugation at 12 000 rpm for 20 min.^{46 (link)}