Off-on Manipulation Of Enzyme Activity By A Near-infrared Laser

As a green and efficient catalyst,enzymes often play a key role in biochemical reactions.However,it is difficult to control the catalytic activity of natural enzymes in the reaction process.Therefore,the construction of smart enzymes with controllable activity becomes an attractive research field.Different types of smart enzymes responsive to light,temperature,ion concentration,magnetic field,external tension and redox property have been built in recent years.Among them,the photo-responsive enzymes arouse widespread concern for their noninvasive speciality,spatiotemporal specificity and non-contamination regulation.But most of the current photoresponsive smart enzymes are constructed by combining azobenzene analogues,apirapyranes or photosensitive domain of protein with enzymes by chemical modification or gene coding technology which usually require high-energy lasers such as ultraviolet light or blue light to triger the photosensitive groups.The preparation progress of these smart enzymes is compex,the cost is high,and it is difficult to achieve off-on switching control.What's more,the low biological safety and poor tissue penetration of ultraviolet light or blue light make it not suitalble for in vivo research.In order to solve the problems above,we reported a facile strategy for reversibly switching off and on the activity of several enzymes in response to a near-infrared light.Enzymes towards macromolecule substrates like glucoamylase(GA),proteinase K(ProK)and Deoxyribonuclease I(DNase I)were chosen as model enzymes.Then they were embedded with ultrasmall platinum nanoparticle and further decorated by a thermoresponsive copolymer with an upper critical solution temperature(UCST)which was synthesized by radical polymerization of acrylamide and acrylonitrile,finaly we got polymer engineering enzyme-Pt hybrids(PE-GA/Pt,PE-ProK/Pt and PE-DNase I/Pt).We synthesized four PE-GA/Pt samples with different phase transition temperatures(15.6 ?,27.1 ?,40.3 ? and 46.9 ?)by changing the ratio of acrylamide and acrylonitrile.The enzymatic activity was efficiently inhibited by blocking the macromolecule substrates from the catalytic center of the enzymes when the temperature was lower than phase trasition temperature.Upon near-infrared light irradiation,the heat generated by photothermal effect of platinum nanoparticles in the enzyme caused a phase transition of the thermoresponsive copolymers on enzyme surface,resulting in the dissolution of polymer aggregates and the recovery of enzyme activity.After near-infrared light irradiation,the enzymatic activity of PE-GA/Pt could be increased to 50 times of that without irradiation.Furthermore,the enzymatic activity of PE-GA/Pt could be reversibly turned off and on by near-infrared light irradiation and could maintain over 60% of the initial enzyme activity after six off-on cycles.Based on the reaction among PE-GA/Pt,glucose oxidase and horseradish peroxidase,we applied PE-GA/Pt to photo-patterning and successfully printed patterns of different colors and shapes via near-infrared light.The enzymatic activiy detection results show that the activities of PE-ProK/Pt and PE-DNasse I/Pt towards protein and plasmid DNA substrates were improved by 22 and 61 folds by light irradiation proving the generality of this method to different enzymes.In conclusion,this study provides a facile and efficient method for reversable “offon” control of enzyme activity by combining photothermal nanomaterial with temperature-resonsive polymer and using near-infrared light with stronger tissue penetration and higher biological safety intead of high energy lasers such as ultraviolet and blue light.The results of this study show that this method can be applied to photolithography and has potential application value in biological therapy.