Nanogels For Enzyme Integration And Catalytic Oxidation Applications

In recent years,the domestic and international cancer situation is severe,therefore safe and efficient tumor diagnosis and treatment have attracted more and more researchers’attention.Many cellular reactions in the metabolic pathways of living organisms are catalyzed by matrices such as multi-enzyme complexes bound to gel tissues rather than free enzymes.The matrices include extracellular matrices（ECM）of gel chimeric enzyme structure composed of proteoglycans such as collagen and remodeling enzymes,the cell membrane of the chimeric semi-solid gel structure of enzymes,surface antigens and other molecules,and the nuclear chromatin of the elastic gel structure of nucleic acid protein/DNA.Enzymes,together with the matrix environment in which they assemble/chimeric,constitute an essential part of life at the nanoscale.It is of great significance to study how to biomimetic construct enzyme-loaded functional nanoreactor materials and use its special enzymatic reaction to achieve efficient and safe tumor treatment.This paper firstly constructed an enzyme-loaded hybrid nanogel system,and proposes a combined biological and physical tumor therapy strategy induced by cascade enzyme catalysis.Secondly,a silica nanoreactor with an enzyme-loaded hierarchical pore structure was constructed,and the compartmentalized enzymatic multi-channel singlet oxygen（¹O₂）generation system was studied for superactive biocatalytic tumor therapy.Finally,a series of amino acid coordination mimetic enzyme systems were systematically developed,and their multi-enzyme mimetic activities,gelation properties and gelation mechanisms were studied,which provided ideas for the in situ construction of multi-scale gel materials.The details are as follows:（1）Design and construction of biomimetic peroxisome materials and research on their biocatalytic properties:biomimetic peroxisome structure and function construction of functional enzyme-loaded nanogel systems to achieve biomimetic and efficient tumor physio-biochemical treatment research are studied.We integrated lactate oxidase（LOx）and catalase（CAT）into Fe₃O₄ nanoparticle/indocyanine green（ICG）co-loaded hybrid nanogels.Based on the O₂ redistribution and H₂O₂ activation by cascading LOx and CAT catalytic metabolic regulation,hydroxyl radical（OH·）and singlet oxygen production can be modulated for glutathione（GSH）-activated chemodynamic therapy（CDT）and near infrared light（NIR）-triggered photodynamic therapy（PDT）,by manipulating the ratio of LOx and CAT to catalyze endogenous lactate to produce H₂O₂ and further cascade decomposing H₂O₂ into O₂.The regulation reactions of the significantly elevate the intracellular ROS level and cause fatal damage to cancer cells inducing the effective inhibition of tumor growth.This photodynamic therapy mode enhanced by enzyme through cascade enzyme catalysis,provides a new idea for efficient and responsive tumor therapy.（2）Multi-enzyme-regulated compartmentalized nanoreactors and their ultra-active catalytic therapeutic applications:A compartmentalized multistage nanoreactor was developed.We have developed compartmental hierarchical nanoreactors as an efficient multi-pathway singlet oxygen（¹O₂）generation system for superactive biocatalytic tumor therapy.The penetrated super cavity and connected dual-mesopore channels of the compartmental multienzyme nanoreactors are designed using the proposed heterogeneous template assembly for multi-enzyme complex（superoxide dismutase（SOD）-lactoperoxidase（LPO））and photosensitizer molecule（ICG）encapsulation.Benefited by the enhanced direct substrate diffusion between the interacting SOD-LPO complex and decreased the external diffusion,the parallel catalysis combined by the superactive cascade biocatalysis and enzyme-promoted photosensitization effect is verified by this compartmental silica nanoreactor system.The parallel pathways not only make full use of the products of SOD（H₂O₂ and O₂）,but also exhibit outstanding capability for ¹O₂ production.Both in vitro and in vivo studies demonstrate the synergetic ¹O₂-mediated inhibition of tumor proliferation,lending this strategy great potential for the treatment of hypoxic tumors.（3）Development and property study of amino acid coordination mimic enzyme system:based on the coordination strategy of amino acids and metal ions,a series of amino acid metal complexes were successfully prepared,including ferrous arginine,ferrous glycinate,ferrous aspartate,ferrous histidine,ferrous lysine,ferrous serine,ferrous phenylalanine,copper aspartate,zinc aspartate,and molybdenum aspartate.We further explored the multi-enzyme mimic activity（peroxidase（POD）,SOD,NADH oxidase（NOx）and nitric oxide synthase（NOS））,gelation properties and gelation mechanism of the amino acid ferrous acid.The strategy of self-triggered in situ construction of enzyme-loaded gels by these complexes is emphasized.The transition of gel size from microgels to macrogels can be realized by adjusting the monomer concentration.By introducing the fifth coordination of guanine,the activity of amino acid ferrous simulating POD can be improved.Further adding NADH coenzyme can greatly improve the activity of amino acid ferrous simulating POD.The multi-enzyme mimetic activity of amino acid ferrous iron was tested,and it was proved that this series of mimetic enzymes had mimetic SOD,NOx and NOS enzyme activities.The design and preparation of a simple and novel amino acid coordination mimetic enzyme system provides an idea for the in situ construction of multiscale gel materials.