Tris hydrochloride buffer

Calcium nitrate,
tin chloride, dopamine, acridine orange, l-cysteine, EDTA,
and tris hydrochloride buffer salt were obtained from Sigma-Aldrich.
The sensing-related DNA samples were procured from Integrated DNA
Technologies, and the DNA sequences used in this paper are listed
as follows.
DNA1: 3′-CTGGAAGGAAAGGAAGGCCTACTTCGACTACAGTCTCAG-5′
DNA2: 3′-TACGGATCGATGATCGGATCATCGCAGTCC-5′
DNA3: 3′-TAGGGTTGGGTATGGGAAGGGTCCCTCCAACCTATACCTTCCACCCA-5′
DNA4: 3′-TTAGGATCTGGTTACTCCGTCTACCT-5′
DNA5:
3′-TCGACGTAGCTATCGTACGCCTACCTCTA-5′
The stock
solution of aptamer was prepared by dissolving 50 mM
Tris-HCl buffer and stored at 4 °C. The nitrate salts of lead,
silver, mercury, calcium, and nickel, and the chloride salts of cobalt,
copper, barium, ferric, magnesium, ferrous, manganese, and other standard
chemicals were purchased at the highest purity levels from SRL and
Sigma-Aldrich (India). Throughout the experiment, deionized (DI) water
was used.

Amorphous fluoroplastics precursor (6%; Chemours, Teflon AF 1601), amorphous FP CYTOP (AGC Chemicals, CTL-809M), fluorinated solvent solution (AGC Chemicals, SOLV180), APTS (95%; Dieckmann), deionized water [resistivity of 18.3 megohm·cm, produced by a deionized water system (DINEC, Hong Kong)], hydrogen peroxide solution (30%; Sigma-Aldrich), sulfuric acid solution (≥99%; Sigma-Aldrich), BSA (≥99%; Sigma-Aldrich), tris hydrochloride buffer (>99%; Sigma-Aldrich), sodium hydroxide (≥98%; Sigma-Aldrich), hydrochloric acid (37% in water), ferric chloride (≥99%; Sigma-Aldrich), ethanol (≥99%; Sigma-Aldrich), glycerin (≥99%; Sigma-Aldrich), glycol (≥99%; Sigma-Aldrich), sodium chloride (≥99%; Sigma-Aldrich), and sodium alga acid (low-viscosity model; Sigma-Aldrich) were used without further purification. Ultra-Ever Dry was purchased from Ultra Tech International Inc. Copper was purchased from the common hardware stores in Hong Kong.