Determination of Cholesterol by Colorimetry and Surface-Enhanced Raman Spectroscopy Using Gold Nanoparticles Decorated with a Fe(III)-Tetra(4-Carboxyphenyl)-Porphine Metal-Organic Framework

A simple and facile hydrothermal method was developed for the synthesis of gold nanoparticles (AuNPs) adorned with two-dimensional (2D) heme-like Fe(III)-tetra(4-carboxyphenyl)-porphine (TCPP-Fe) metal-organic framework (MOF) nanocomposite. Notably, the synthesized hybrid nanomaterial (AuNPs/TCPP-Fe hybrid nanosheets) exhibited excellent peroxidase (POD)-like nanoenzymes activity and Raman activity under ultrasound (US) and near-infrared (NIR) irradiation at physiological pH conditions. A cascade colorimetric-SERS dual-mode method was developed for sensitive and rapid cholesterol determination based on the excellent POD-like properties and surface-enhanced Raman spectroscopy (SERS) activity of AuNPs/TCPP-Fe nanoenzymes. The TCPP-Fe nanoenzymes combined with cholesterol oxidase catalyze a cascade reaction to convert cholesterol to H2O2, which then oxidizes colorless, low Raman-activity 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue, high-Raman-activity oxidation product (ox-TMB). The cholesterol in human serum of colorimetric-SERS was successfully assayed with good recovery from 97.8 to 103.7%. The study paves a new method for designing a nanocomposite-based SERS for biochemistry analysis.