Preparation Of Layered Double Hydroxide-based Nanotherapy System For Reactive Oxygen Species Based Tumor Dynamic Therapy

Cancer,as a major medical problem in the world,poses a serious threat to human health with its high incidence rate and high mortality.Reactive oxygen species（ROS）,as a kind of intracellular chemical substrate,plays an irreplaceable role in the cell life cycle.Abnormal increase of intracellular ROS level can lead to non-specific oxidative damage to key cellular biomolecules and induce cell death.Based on this,ROS-based dynamic therapies,such as chemodynamic therapy（CDT）,photodynamic therapy（PDT）and sonodynamic therapy（SDT）,have developed into a kind of promising cancer treatment.The design of ROS-based nanomaterials has also received extensive attention.However,most of the currently reported ROS-based nanomaterials exhibit low ROS generation efficiency,which greatly limits the application of ROS-based dynamic therapy in the field of clinical cancer treatment.Therefore,the development of novel ROS-based nanomaterials with good biocompatibility and high ROS yield is the key to improve the therapeutic performance of ROS-based dynamic therapy.In addition,through the development of multimodal ROS-based nanomaterials,the advantages of different ROS-based dynamic therapies can be complementary to obtain more ideal synergistic therapeutic effects,which is also a research hotspot in this field.Focusing on the aforementioned key scientific issues,based on the structural characteristics of layered double hydroxides（LDHs）nanomaterials and their unique physicochemical properties,this paper develops the construction strategies of new ROS-based nanomaterials,and prepares a series of novel LDHs-based nanomaterials for ROS-based dynamic therapy,which provides theoretical basis and practical verification for expanding the clinical application of ROS-based dynamic therapy.The main research contents of this paper are as follows:1.Preparation of CoFe-LDHs Fenton therapeutic agent for CDTCDT is based on Fenton reaction to catalyze the formation of hydroxyl radical（·OH）from H₂O₂in the tumor microenvironment to kill cancer cells,thus achieving tumor-specific treatment.However,it usually suffers from low Fenton reaction rate and low·OH generation efficiency.To solve this key scientific problem,monolayer CoFe-LDHs nanosheets rich in Fenton metal ions were constructed through“bottom-up”method.Fenton metal ions exhibit atomically dispersed arrangement on LDHs matrix,providing abundant Fenton reaction active sites,greatly improving the Fenton reaction rate(rate constant 3.26×10^-4s^-1)of CoFe-LDHs,which is 1-3 orders of magnitude higher than other iron-based Fenton reagents.Further loading glucose oxidase（GOD）that can catalyze H₂O₂generation in situ,a novel Fenton therapeutic agent（GOD/CoFe-LDHs）with H₂O₂self-supplying properties was obtained.Under weak acid condition,GOD/CoFe-LDHs show high·OH production efficiency,with the maximum reaction rate(V_max)of 2.23×10^-6M and the Michaelis constant（K_M）of 5.40 m M.Both in vitro and in vivo experiments have proved that GOD/CoFe-LDHs nanosheets exhibit good biocompatibility and efficient Fenton catalytic performance,and can be used for tumor-specific therapy with H₂O₂self-supply,which has great application potential in clinical cancer treatment.2.Preparation of LDHs-based photosensitizer for PDT/CDT synergistic therapyPDT is a new technology that utilizes lasers to activate photosensitizers（PSs）at tumor sites to produce ROS for cancer treatment,with high selectivity and spatiotemporal accuracy.Light source,PSs and O₂are the core three elements of PDT.However,low ROS generation efficiency of PSs and hypoxic microenvironment of tumors greatly limit the application scope of PDT.In response to the above key scientific issues,the O₂-independent NiCoTi-LDH PS was constructed using“bottom-up”method.A large number of oxygen vacancies（OVs）on NiCoTi-LDH can be produced by etching under acidic environment,which can facilitate the separation of electron-hole pairs.Based on this,NiCoTi-LDH nanosheets show OVs-promoted electron-hole pairs separation and photogenerated hole-induced O₂-independent ROS generation.Since photogenerated electrons can promote the effective conversion between Co³⁺and Co²⁺,NiCoTi-LDH can continuously catalyze the generation of·OH from H₂O₂through Fenton-like reaction,thus realizing CDT.Laser irradiation can further enhance the catalytic ability of NiCoTi-LDH nanosheets to promote ROS generation,enabling NiCoTi-LDH nanosheets to show better ROS generation performance than the traditional inorganic Ti O₂PS.In vitro and in vivo assays indicate that NiCoTi-LDH can effectively induce cell apoptosis and significantly inhibit tumor growth under laser irradiation.This study reports a novel p H-responsive inorganic PS with OVs-facilitated PDT/CDT synergistic performance,providing an example for the realization of synergistic therapy with a single intelligent nanoagent.3.Preparation of novel LDHs-based sonosensitizer for SDTSDT can induce tumor ablation by activating sonosensitizers in tumor tissues to generate ROS under US irradiation,which has the advantage of strong tissue penetration.However,traditional sonosensitizers are generally limited by low US absorption and electron-hole separation efficiencies,leading to insufficient ROS yield.Focusing on this key scientific problem,ultrathin CoW-LDH nanosheets were designed as highly effective sonosensitizers through crystal phase transition strategy.The hydrothermal-synthesized CoW-LDH nanosheets can be transformed from polycrystalline to amorphous by simple acid etching treatment,resulting in the generation of rich defects on CoW-LDH and the reduction of bandgap.Compared with polycrystalline CoW-LDH nanosheets,amorphous CoW-LDH（a-CoW-LDH）nanosheets show higher ROS generation activity（increased by5 times）under US irradiation,which is also about 17 times that of commonly used Ti O₂sonosensitizer.After modification with polyethylene glycol（PEG）,a-CoW-LDH-PEG nanosheets can be used as highly effective sonosensitizer to achieve cancer cell death and tumor eradication under US irradiation.This research provides a new idea for the development of LDHs-based sonosensitizer,and opens up a new research path for the application of amorphous 2D LDHs nanosheets for effective SDT.