Synthesis And Adsorption Property Of N-(9-Fluorenylmethoxycarbonyl)-D-tryptophan Molecular Imprinted Polymers

As a new method of adsorption,Molecularly Imprinted Technique?MIT?is widely used in many fields with the unique specificity and selectivity.Tryptophan is an essential amino acid,widely found in millet,beans,dairy products,fish and other foods rich in protein?0.2%?,marine also has trace amounts of tryptophan.Tryptophan for the growth of animals and plants,the treatment of insomnia,depression,pellagra plays a vital role.In this paper,the MIPs was synthesized by bulk polymerization,using Fmoc-D-tryptophan?Fmoc-D-Trp?as the template molecule,acrylamide?AM?as the functional monomer,ethylene glycol dimethacrylate?EGDMA?as the crosslinking agent,2,2-Azobisisobutyronitrile?AIBN?as the initiator.The molecular imprinted polymers were characterized by SEM,TGA,BET,FT-IR.The experimental results show that the acrylamide as functional monomer,functional monomer/imprinted molecular molar ratio was 4?1,prepolymerization temperature was 0?,the amount of solvent was 3ml,EGDMA was 1.88mL,AIBN was 25mg,MIPs obtainedgood adsorption capacity,and the maximum adsorption capacity was 2.767mg/g.Based on this,MIPs were used as the adsorbent,and the adsorption effect was studied by static and dynamic adsorption methods.In the static adsorption experiment were investigated that the adsorption time,adsorption temperature,adsorption agent dosage,sample concentration and other conditions of MIPs adsorption effect;The experimental results show that:adsorption time was 8h,adsorption temperature was 15?,adsorbent dosage was 25mg,sample concentration was 0.05mg/mL,the MIPs adsorption effect is the best,the adsorption amount was 3.253mg/g.In the dynamic adsorption experiment,research the adsorption effects of Fmoc-D-Trp sample concentration,sample type and adsorbent dosage of MIPs,the experimental results show that the dynamic adsorption condition of sample concentration was 0.05mg/mL,the solute was Fmoc-D-Trp,the dosage of the adsorbent was 24g,dynamic adsorption effects was the best,first appeared at the exit time t_o was 4min,C₀ was 0.00037mg/mL;breaking point time t_b was 6-7min,C_b was 0.0025mg/mL;t_e was 35min,C_e was 0.0513mg/mL.At the same time,research the effects of Fmoc-D,L-Tp the competitive adsorption and structural analogues of D-Phe,t₀ was 2min,C₀ was 0.00083-0.0022mg/mL;t_b was 5-6min,C_b was0.0025mg/mL;t_e was 35min,C_e was 0.0489-0.0513mg/mL,showed that MIPs has specific recognition ability for the imprinted molecule Fmoc-D-Trp.At the end of the adsorption process of Langmuir adsorption isotherm and Freundlich adsorption isotherm were used to fit the results of the adsorption processes,Through the comparison can be summarized in this paper,indicating that the adsorption process was a single molecular layer adsorption,and the adsorption of each binding site with two imprinting molecular.The pseudo-first-order model and pseudo-second-order model were used to fit the results of the adsorption processes,indicating that the adsorption process belongs to the pseudo-second-order model.At the same time,the Scatchard curve also was used to fit the results of the adsorption processes,it can be drawn that MIPs has two types of binding sites,specific binding sites:K_D,1=0.0647mol/mL,Q_max,1=6.038mmol/g,nonspecific binding site:K_D,2=0.247 mol/mL,Q_max,2=11.865mmol/g?...