Aptamer-regulated COF Nanocatalytic Amplification-SERS/RRS/Abs Spectral Method For Some Pollutants

Covalent organic framework(COF)is a new kind of crystalline porous organic material with excellent properties,such as low weight density,adjustable pore size and structure,various synthesis methods and easy functional modification.Due to the excellent properties of COF,it has been widely used in the fields of gas adsorption,storage and separation,catalysis,and photoelectric conversion.However,there are few quantitative analysis methods for molecular spectroscopy based on COF composites,especially in the application of surface-enhanced Raman scattering(SERS),resonant Rayleigh scattering(RRS),and surface plasmon resonance absorption spectroscopy(Abs).Therefore,it is of great significance to combine COF composites with SERS/RRS/Abs to construct a series of quantitative analysis methods.In this paper,we prepared a series of COF composites(nanocatalysts)and used them to construct nanocatalytic amplification reactions,and also investigated the catalytic amplification reaction mechanism of COF composites.Subsequently,a series of sensitive and simple quantitative SERS/RRS/Abs analysis methods were constructed based on the regulation of the catalytic activity of COF composites by specific aptamer reactions.The specific research contents are as follows:Due to the non-degradability of lead,it in food poses a huge threat to human health.Therefore,it is very important to establish a sensitive and rapid detection method for Pb²⁺in food.In this paper,a new palladium-doped covalent organic framework(COF_Pd,TpPa _Pd)was prepared using CO as the reducing agent,and it was characterized in details.Experiments show that TpPa _Pdstrongly catalyze the reduction of Ni(II)by sodium hypophosphite to form Ni-P alloys,and the system has a surface plasmon resonance(SPR)absorption peak at 395 nm.Combing the nanocatalytic reaction with the DNAzyme reaction of the aptamer(Apt)-Pb²⁺-hemin(HM),a new SPR spectrophotometric method was established to detect 0.001-0.1 nmol/L Pb²⁺in food sample,with a detection limit of 0.0004 nmol/L.Two COFs of BzBD and BzBD loaded Pd nanoclusters(BzBD_Pd)were prepared using 1,3,5-benzenetricarboxaldehyde(Bz),benzidine(BD)and CO reducing agent,and were characterized by transmission electron microscopy(TEM),X-ray powder diffraction(XRD),infrared spectroscopy(IR)and other techniques.BzBD_Pd can strongly catalyze the new and stable Au@Ni P nanoreaction that exhibit a strong resonance Rayleigh scattering(RRS)peak at 538 nm and a surface plasmon resonance(SPR)absorption peak at 395 nm,and the sensitive and facile RRS technique was used to study the indicator reaction.Combining the nanocatalytic amplification reaction with specific aptamer(Apt)of some target molecules such as melamine(ML),urea(UR)and bisphenol A(BPA),a simple,sensitive and selective Apt RRS assay platform was established.The linear range of the RRS detection platform for melamine is 0.0025-0.04 nmol/L,and the detection limit(DL)is 1.96×10^-4 nmol/L.In addition,ML in real sample was analyzed,the stability of BzBD,BzBD_Pd,Pd NPs and the catalytic mechanism of COF_Pd were also considered.Herein,a stable and highly catalytic covalent organic framework loaded-HB(COF_HB)was synthesized,using 1,3,5-benzenetricarboxaldehyde(Bz),benzidine(BD),and 4-hexyloxybenzoicacid(HB)liquid crystals as precursors,and it has been characterized in detail by TEM,XRD and molecular spectral techniques.Using the slope procedure to evaluate nanocatalysis,COF_HB exhibits strongest catalysis of mandelic acid-HAuCl₄ nanogold reaction to generate gold nanoparticles(AuNPs),and the generated AuNPs have strong resonance Rayleigh scattering(RRS)and surface plasmon resonance absorption(Abs)signals.When victoria blue 4R(VB4r)is added as a molecular probe,it exhibits a strong surface-enhanced Raman scattering(SERS)signal.This highly sensitive nano-indicator reaction can be coupled with specific ampicillin sodium aptamer(Apt _AMP)reaction to fabricate a highly sensitive and selective SERS/RRS/Abs trimode aptamer sensoring platform for the detection of AMP,and a reasonable COF_HB catalytic amplification mechanism was proposed.In addition,the nanocatalytic amplification aptamer SERS platform can also be used for the detection of other small molecular drugs including sulfadimethoxine(SDM),tetracycline(TEC)and oxytetracycline(OTC).In this paper,a series of nanocatalytic amplification reactions were constructed using COF composites as nanocatalysts,and the variation law of catalytic activity of COF composites was discussed,and a reasonable catalytic amplification mechanism of COF composites was proposed.Subsequently,a series of SERS/RRS/Abs quantitative analysis methods were constructed by using specific aptamer reaction to regulate nanocatalytic amplification reactions,which provide certain guidance for improving the sensitivity of molecular spectral quantitative analysis methods.The construction of aptamer-mediated COF composites nanocatalysis-SERS/RRS/Abs quantitative analysis method expands the application range of molecular spectroscopy quantitative analysis method,which has certain practical significance.