A novel sensing platform for sensitive cholesterol detection by using positively charged gold nanoparticles

- A novel platform: Precipitation of (+)AuNPs was introduced for cholesterol detection for the first time.
- 4 nm of (+)AuNPs were introduced as signal probe for the first time.
- Such sensing method more tolerant to the sensing environments because of the stability of (+)AuNPs.
- A low detection limit of 335 pM was obtained for cholesterol detection.
- Satisfactory results were obtained for cholesterol detection in serum samples.

This work described a label-free platform for sensitive cholesterol detection upon the precipitation of cetyltrimethyl ammonium bromide (CTAB) stabilized gold nanoparticles (AuNPs). Modifying with CTAB, the stability of AuNPs was greatly improved compared to conventional used AuNPs, and the surface of them was positively charged, which could effectively adsorb with negatively charged DNA detection probe (DP) based on electrostatic adsorption, and inducing the precipitation of them. Tremendous H2O2 would produce based on the reaction of cholesterol with oxygen by using cholesterol oxidase (ChOx) as the catalyzer, and followed the happen of Fenton reaction in the presence of Fe2+ to generate OH, inducing the cleavage of DP into DNA fragments. As a result, the adsorption ability of AuNPs decreased, accompanying with a decrease of AuNPs precipitation. Then, based on detecting the absorption spectra change of AuNPs in supernatant along with the increase of cholesterol concentration, sensitive and simple visual-based cholesterol detection was realized with a detection limit of 335 pM. Such method showed high selectivity for the detection of cholesterol. Moreover, the high stability of such AuNPs in solution that contained salt, protein or other metal ions, making our sensing method have a potential application in bioanalysis.

This work described a novel and simple platform for sensitive detection of cholesterol based on based on the cleavage of detection probe, and observing the absorption spectra change (ΔA) of AuNPs in supernatant.106