Penicillinase-immobilized Phase-change Microcapsules For Detection And Removal Of Penicillins Under Microenvironmental Thermal Management

Penicillin,a low-cost and readily available antibiotic,is widely used in biological treatment and disease prevention at present.However,after long-term use of penicillin,the antibiotic tends to accumulate in organisms and eventually flood the environment,posing a greater threat to the ecological environment and the health of organisms.Therefore,accurate detection and removal of penicillin is an urgent ecological research field.The traditional methods used to detect penicillin（such as capillary electrophoresis,liquid chromatography and so on）have great limitations in terms of price and sensitivity,so it is of great significance to explore a more accurate and efficient method.In this project,we developed an immobilized penicillinase detection system with phase-change energy storage microcapsules as a carrier.Through its microenvironment thermal management capability,the system can improve the specific detection efficiency and removal efficiency of penicillinase in the detection of penicillin within a certain temperature range.In this experiment,by in-situ polymerization a core-shell phase-change microcapsules（SiO₂-MEPCM）were synthesized with n-docosane tightly wrapped with silica;Then,the microcapsules were coated with glutaraldehyde cross-linked chitosan to obtain phase-change energy storage microcapsules（CS@SiO₂-MEPCM）with good biocompatibility;Finally,through covalent bonding,penicillinase was immobilized on chitosan to prepare immobilized penicillinase（Pen X-CS@SiO₂-MEPCM）with thermoregulation ability.By SEM,TEM,XPS,EDX,FT-IR and XRD,it is proved that the sample has good morphology and desired chemical composition;Through DSC,TGA,DTG and multi-functional thermal imager,it is shown that the phase change microcapsules have good energy storage capacity(ΔH_c=125.2 J·g^-1,ΔH_m=127.2 J·g^-1),the anti-phase change core material leakage capability and thermal stability;The optimum conditions for sample preparation was determined by the glutaraldehyde content test（GLA concentration=2%）;the temperature stability,acid and alkali resistance,storage stability,thermal cycling stability,low temperature storage tolerance and substrate specificity of immobilized penicillinase are investigated by testing the immobilized enzymes under different conditions;The removal rate of penicillin（94.71%）was detected at 50℃,indicating the superiority of immobilized penicillinase in hydrolyzing penicillin at high temperature;The kinetics of the enzymatic reaction shows that the immobilized penicillinase has a good affinity for the substrate at high temperature(K_m=0.124 mg/mL,V_max=0.439ΔOD/min);Finally,the standard addition test of immobilized penicillinase was carried out in milk samples at 50℃,showing that its application feasibility in real life was good（Recovery rate=79.39%,RSD=0.39%）.The immobilized penicillinase prepared in this project has excellent biocatalytic ability at high temperature.It can be predicted that the phase-changemicrocapsule-immobilizedpenicillinase（Pen X-CS@SiO₂-MEPCM）has broad application prospects and great development potential in realizing continuous high-precision detection and efficient removal of penicillin under harsh conditions.