Adenine

Potassium ferricyanide, graphite powder, melamine, and Whatman qualitative filter paper Grade 1 were bought from Sigma-Aldrich. Nucleic acid bases like guanine, adenine, thymine, and sodium hydroxide, potassium chloride, urea, ethanol, acetic acid, hydrochloric acid, potassium dihydrogen phosphate (KH₂PO₄), N-cetyl-N, N, N trimethyl ammonium bromide (CTAB), and potassium hydrogen phosphate (K₂HPO₄) were procured from Hi-Media, India.

All the chemicals used were of analytical grade. Auric chloride (HAuCl₄), sodium dodecylbenzene sulfonate (SDBS), haemoglobin, guanine, thymine, adenine, cytosine, bilirubin, glucose, urea and sodium borohydride (NaBH₄) were purchased from Himedia (Mumbai, India). The structures of all of the nucleobases along with glucose, urea and bilirubin are shown in the ESI in Fig. S1.† The standard stock solutions of the biomolecules were prepared by dissolving an appropriate amount of each substance in 10 mL of distilled water (DW) or methanol. The working standard solutions were prepared by diluting the stock standard solution. 0.1 M NaOH and 0.1 M HCl solutions were prepared and used for maintaining the pH of the sample solution.