Nucleotide-mediated Synthesis Of Pt Nanoclusters And Their Application In Biological Detection

Nucleotides(NMP)are basic building blocks of nucleic acids with small molecular weights and simple structures.They are enriched with electron-rich groups that can coordinate with metals and in situ reduce metal ions under certain conditions.Thus,they possess good application prospects in the synthesis and regulation of functional metal nanomaterials.In this thesis,Pt nanoclusters(Pt NCs)with enzyme-like activities were synthesized in one step by using natural NMPs as stabilizers and reducing agents.The effects of chemical structures of NMPs on the catalytic performance of nanozymes were investigated,and their applications in the field of biological detection were explored.Four natural NMPs including cytidine monophosphate(CMP),thymidine monophosphate(TMP),guanosine monophosphate(GMP)and adenosine monophosphate(AMP)were used as both nucleation templates and reducing agents to prepare highly dispersed Pt-NMP nanoclusters(Pt-NMP NCs)in aqueous solution.The interaction mechanism between K₂PtCl₄ and NMP were deeply studied.NMP can control both size and valence distribution of nanozymes by regulating the coordination environment of PtCl₄^2-.The peroxidase activities of Pt-NMP NCs were closely related to the chemical structures of NMPs and the molar ratios of[K₂PtCl₄]/[NMP].The catalytic performance of Pt-NMP NCs decreased in the following order:Pt-CMP>Pt-TMP>Pt-GMP>Pt-AMP.As the[K₂PtCl₄]/[CMP]molar ratio was 0.5,Pt-CMP NCs showed the highest peroxidase mimicking activity rather than the oxidase-like activity.It exhibited high affinity for 3,3',5,5'-tetramethylbenzidine(TMB)and hydrogen peroxide(H₂O₂).Colorimetric assays for H₂O₂ and glucose were constructed based on the peroxidase-like activity of Pt-CMP NCs.The detection range for H₂O₂ was 10-200?M,and the limit of detection(LOD)was 0.53?M.The detection range for glucose was 5-100?M with the LOD of 0.12?M,which presented high anti-interference ability.This colorimetric method showed potential application prospects in human serum samples.Since Pt-NMP NCs synthesized in aqueous solution exhibited extremely weak oxidase-like activity,the combination of polyols with NMP was further studied for the development of Pt NCs with oxidase mimicking activities.CMP and GMP were selected as templates and reductants to synthesize Pt-NMP/EG NCs with peroxidase-like and oxidase-like activities in ethylene glycol(EG).The effects of chemical structures of NMPs,solvent,and synthesis temperature on the particle size,crystal structure,valence state,charge properties,and enzyme-like activities of nanozymes were further studied.The synergy of NMP and EG,both as the solvent and reductant,can effectively accelerate the reduction rate of metal precursors,thereby reducing Pt(II)to Pt⁰ atoms.While in aqueous solution,NMP can only reduce Pt(II)precursors to positively charged Pt^?+species.As the reaction temperature was 60°C and the molar ratio of[K₂PtCl₄]/[NMP]molar ratio was 1,Pt-NMP/EG NCs exhibited the highest enzyme-like activity.As the oxidase mimic,the Km value of Pt-CMP/EG NCs for TMB was 0.052 m M.Based on the oxidase-like activity of Pt-CMP/EG NCs,a colorimetric assay for quantitative detection of acid phosphatase(ACP)was established.The linear detection range was 1-12 U/L and LOD was 0.21 U/L.