Preparation Of Silica-Based Mesoporous Ionic Imprinting Materials For Detection

Ion-imprinted fluorescent sensors are based on molecularly imprinted polymers（MIPs）for selective recognition of target ions and highly sensitive ion fluorescent materials.The change of fluorescence intensity can be used as a reference for the change of ion concentration.Ion imprinted fluorescent sensors showed the characteristics high selectivity,good structural predictability,stability and low cost,which made them ideal sensor sensitive materials.A core-shell structured ion-imprinted fluorescent sensor was synthesized using carbon quantum dots（CDs）,graphene quantum dots（GQDs）and europium ligands as fluorescent signals for the detection of Pb²⁺in the aqueous environment by a precipitation polymerisation method.（1）The blue fluorescent CDs were synthesized by the hydrothermal method as the fluorescence response signal,and the silicon-coated carbon quantum dots（CDs@SiO₂）with modified CDs@SiO₂ as the core were synthesized by the inverse microemulsion method.A core-shell ion-imprinted fluorescent sensor（CDs@SiO₂@IIPs）was synthesized by precipitation polymerization of 3-aminopropane with triethoxysilicon（APTES）as the functional monomer and ethyl orthosilicate（TEOS）as the cross-linking agent.The linear detection range was 100.00～500.00 nmol/L,the linear correlation coefficient R² was 0.9918,and the imprinting factor IF=2.64.（2）A mesoporous ion-imprinted fluorescent sensor（CDs@SiO₂@MIIPs）with a modified CDs@SiO₂ core,APTES as a functional monomer,TEOS as a cross-linking agent and CTAB as a template was synthesized.The response time was 1 min,the linear detection range was 10.00～100.00 nmol/L,the linear correlation coefficient R² was 0.9990 and IF=5.13.（3）A mesoporous core-shell ratio ion-imprinted fluorescent sensor（GQDs@SiO₂@Eu-MIIPS）with APTES and europium bifunctional monomers was prepared using blue fluorescent GQDs as the reference signal and red fluorescent europium ligands as the response signal.The linear detection range was 10.00～100.00 nmol/L,with a linear correlation coefficient R² of 0.9985 and IF=5.70.The visual detection from red fluorescence to blue fluorescence was also achieved during the assay.