▎ 摘　　要

NOVELTY - Preparation of ferrosoferric oxide-graphene oxide-silver co-doped gold nano-star surface-enhanced Raman spectroscopy (SERS) substrate involves dispersing ferrosoferric oxide doped graphene oxide solution with silver nitrate, stirring, adding trisodium citrate, reacting to obtain black precipitate, dispersing in ethanol to obtain ferrosoferric oxide-graphene oxide-silver co-doped SERS solution, adding chloroauric acid solution to water, adding p-mercaptobenzonitrile solution to gold nano-star solution, stirring, washing, adding cortisol monoclonal antibody to SERS solution, shaking, adding bovine serum albumin (BSA) solution, shaking, washing twice, resuspending in phosphate buffered saline solution to obtain SERS substrate solution (A), adding cortisol monoclonal antibody to gold nano-star solution and BSA solution, shaking, to obtain SERS substrate solution (B), mixing SERS substrate solutions, adding cortisol solution of different concentration, shaking and collecting SERS signal. USE - Preparation of ferrosoferric oxide-graphene oxide-silver co-doped gold nano-star surface-enhanced Raman spectroscopy substrate for detection of antigens. ADVANTAGE - The preparation method is simple and carried out using gold nano-stars to connect to Raman beacon molecules with Raman signals connected in the biological silent zone through gold-sulfur bonds to produce substrate high sensitivity to achieve rapid and sensitive detection of antigens and with easy separation process. DETAILED DESCRIPTION - Preparation of ferrosoferric oxide-graphene oxide-silver co-doped gold nano-star surface-enhanced Raman spectroscopy (SERS) substrate involves adding 0.65 g ferric chloride hexahydrate and 0.2 g trisodium citrate to 20 mL ethylene glycol, stirring, adding 1.2 g anhydrous sodium acetate, stirring for 0.5 hour, adding mixture to 50 mL PTFE-lined autoclave, reacting at 200 degrees C for 10 hours, cooling to room temperature, separating magnet to obtain black ferrosoferric oxide and supernatant, washing product with ethanol for 3-5 times, water washing for 3-5 times, vacuum drying in oven, adding 1.5 g ferrosoferric oxide to 50 mL ethanol, ultrasonically processing for 5 minutes, adding 100 mL aminopropyltrimethylsilane, stirring at room temperature for 2 hours, condensing and refluxing for 2 hours, naturally cooling, washing with ethanol for several times to remove excess aminopropyltrimethylsilane, magnetically separating and vacuum drying in oven to obtain amine functionalized ferrosoferric oxide (Fe3O4-NH2), dispersing 1.0 g amine functionalized ferrosoferric oxide to 20 ml of 1.0 mg/mL graphene oxide, magnetically stirring, heating in water bath at 75 degrees C for 1 hour to obtain ferrosoferric oxide doped graphene oxide solution, washing with pure water 3 times to remove excess graphene oxide, dispersing ferrosoferric oxide doped graphene oxide solution with 100 mL of 10 mM silver nitrate, mechanically stirring for 30 minutes to make silver ion reach the surface of ferrosoferric oxide doped graphene oxide, adding 30 mL of 20 mM trisodium citrate, reacting at 60 degrees C for 6 hours, magnetically separating black precipitate, washing three times with ultrapure water and ethanol, dispersing in 20 mL ethanol to obtain ferrosoferric oxide-graphene oxide-silver co-doped SERS solution, adding 10-100 mu L of 1% chloroauric acid solution to 10 mL water, adding 10 mu L of 1 mol/L hydrochloric acid, 10-300 mu L of 0.294 mM gold seed solution, 15-30 mu L of 23.8 mM silver nitrate solution and 30-100 mu L of 0.1 M ascorbic acid solution, stirring at room temperature for 10-60 minutes to obtain gold nano-star solution, adding 20 mu L of 13.56 mM p-mercaptobenzonitrile (4-MBN) solution to 5 mL gold nano-star solution, stirring at room temperature for 1 hour, heat preserving for 24 hours, washing twice with water to remove excess 4-MBN , adding 50 mu L of 1 mg/mL cortisol monoclonal antibody to SERS solution, shaking for 2 hours, adding 50 mu L of 20 mg/mL bovine serum albumin (BSA) solution, shaking for 1 hour to seal the bare site, washing twice, resuspending in 1 mL of 10 mM phosphate buffered saline solution with pH of 7.2 to obtain SERS substrate solution (A), adding 20 mu L of 0.05 mg/mL cortisol monoclonal antibody to gold nano-star solution, shaking for 4 hours, adding 20 mu L of 1 mg/mL BSA solution, shaking for 1 hours, washing twice sites with ultrapure water to obtain SERS substrate solution (B), mixing 200 mu L SERS substrate solution (A) and (B), adding 200 mu L cortisol solution of different concentration, shaking for 2 hours and collecting SERS signal after magnetically separating, where according to the preparation of gold nano-stars, the different concentrations of raw materials have influence on the color, morphology and performance of gold nano-stars.