Construction Of AuNPs/PDA Composite For The Detection Of Creatinine

Polydopamine(PDA)microspheres have been applied in the field of biomedicine because of the high biocompatibility and low cytotoxicity.The monodispersed polydopamine microspheres is easy to prepared,having a low environmental requirement and controllable morphology.Abundant active groups exposed on the surface of PDA microspheres are easy to modify with nanoparticles and exhibit multifunctional properties.This paper is about the preparation of polydopamine microspheres bsaed on the precursor dopamine,then the gold nanoparticles were reduced in situ on the surface of the polydopamine microspheres and further modified into a composite material with excellent SERS effect.At last,the uniform and monodispersed AuNPs/PDA microspheres were fabricated and used as Surface-enhanced Raman scattering(SERS)substrates for creatinine detectionThe major contributions are as follows:1.With the mixture of water and ethanol as solvent,the dopamine as precursor and ammonium hydroxide as catalyst,the dopamine microspheres were synthesized with uniform particle size and regular morphology.Factors influencing the morphology and size of polydopamine microspheres have been investigated,including the amount of ammonium hydroxide,the amount of dopamine and the time of reaction.The polydopamine microspheres could controllable prepare by changing the reaction parameters.We also characterized the morphology and optical properties of microspheres by scanning electron microscope(SEM)and uv-vis spectrophotometer.2.Gold nanoparticles on the surface of PDA microspheres were synthesized in situ and did not need any chemical modification to PDA microspheres,Au3+ combined with negatively charged carboxyl groups easily by electrostatic interaction,and which were reduced to gold nanoparticles by NaBH4;the AuNPs/PDA microspheres were fabricated by the growth of gold nanoparticles on PDA microspheres,which were prepared by the reduction of HAuCl4 with H2O2 in K2CO3-HAuCl4 solution.The existed gold nanoparticles on PDA microspheres could catalyze the reduction of AuCl4-,which make more gold deposited on the PDA microspheres and enlarge existed gold nanoparticles until they touched with each other.To investigate the SERS property of AuNPs/PDA microspheres as substrates,different concentration of NBA were detected.3.AuNPs/PDA microspheres were used as SERS substrates in creatinine detection.We detected SERS signal of creatinine with different concentrations under the condition of aqueous solution,and the SERS spectrum of creatinine still be detected when the concentration as low as 10-7 M.Body fluid is a complex physiological environment,the Raman signal of creatinine is susceptibleto be affected by different substances in the body fluid,so we detected the Raman signal in diferent pH solution and in different interferent to demonstrated the characteristic peak and the change of intensity with the interference.At last,the Raman signal of creatinine in artifical urea was detected and the detection limit was 10-6 M.