Cadmium chloride anhydrous

Determination of cadmium chloride and benzalkonium chloride resistance was performed as previously described (Mullapudi et al., 2008 (link)). Briefly, a single colony from a blood agar plate culture was suspended in 100 μl of tryptic soy broth (Thermo Fisher Scientific, Milan, Italy). Three microliters of the suspension were spotted in duplicate onto: (1) Mueller Hinton Agar Cation adjusted (MHBII) containing 2% defibrinated sheep blood (Thermo Fisher Scientific) (control); (2) MHBII (Thermo Fisher Scientific) containing 2% defibrinated sheep blood (Thermo Fisher Scientific) and 70 mg/l of cadmium chloride anhydrous (Sigma, Milan, Italy); (3) MHBII (Thermo Fisher Scientific) containing 2% defibrinated sheep blood (Thermo Fisher Scientific) and 35 mg/l of cadmium chloride anhydrous (Sigma, Milan, Italy); (4) Mueller Hinton Agar (MHB) (Thermo Fisher Scientific) containing 2% defibrinated sheep blood (Thermo Fisher Scientific) and 10 mg/l benzalkonium chloride (Sigma). Positive and negative control strains were included. All plates were incubated at 37°C for 48 h.

Hexadecyltrimethylammonium bromide (CTAB, >98.0%), L-ascorbic acid (BioUltra, ≥99.5%), silver nitrate (AgNO₃, >99%), gold(III) chloride trihydrate (HAuCl₄·3H₂O, 99%), 3-mercaptopropionic acid (MPA, ≥99%), N-ethyl-N'-(3-dimethylaminopropyl)carbodiimide (EDC, 99%), and N-hydroxysuccinimide (NHs, 99%), cadmium chlorideanhydrous (CdCl₂, 99.999%), selenium powder (Se, 99.8%), sodium borohydride (NaBH₄, 99.99%), and zinc chloride anhydrous were purchased from Sigma-Aldrich. Sodium sulphide (Na₂S, 60–63%) was purchased from Acros Organics, and anhydrous ethanol, sodium hydroxide (NaOH, AR) and hydrochloric acid (HCl, AR) were purchased from Sinopharm Chemical Reagent Co., Ltd. All chemicals were used as received without further purification. Deionized (DI) water used in all the studies was purified by a Milli-Q water purification system.