Amperometric Enzyme Biosensor for the Determination of High Concentration Lactate in Whole Blood of Athletes

<正>Amperometric biosensor applied to the determination of high concentration lactate in serum and whole blood was described.The biosensor was constructed by gold electrode modified with nanoplatinum particles.Lactate oxidase (E.C.1.1.3.2) was immobilized at platinized activated gold electrode which was used for the determination of high concentration lactate at low potential (+0.2 V).The linear calibration graphs were obtained from 1 to 21 mmol·L~ (-1) lactate in serum and from 0.9 to 13.2 mmol.L~ (-1) lactate in whole blood.The correlation coefficients were 0.99 and 0.97,respectively at a steady-state response time of 50 s.

Pd@Ir-LOD multienzyme utilizing endogenous lactate consumption cooperates with photothermal for tumor therapy

Lactic acid(LA)plays a major role in the occurrence,development,and spread of cancer.Enlightened by its high accumulation in tumor site,a novel lactate oxidase(LOD)conjugated two-dimensional Pd@Ir nanoplatform(Pd@Ir-LOD,PIL)was fabricated to combine cascade reaction with photothermal for tumor therapy.In detail,the overexpressed LA in tumor microenvironment(TME)was a key factor to activate the PIL-based cascade reaction:(1)Plenty of H_(2)O_(2)could be generated from LA by the catalysis of LOD with O_(2);(2)potent·OH was produced from H_(2)O_(2)due to the peroxidase(POD)-like activity of PIL;(3)meantime,PIL’s catalase(CAT)-like activity could decompose part H_(2)O_(2)into O_(2)to achieve the purpose of LA cyclic oxidization.Moreover,the reduced glutathione(GSH)scavenging capability of PIL might protect the produced reactive oxygen species(ROS)from being cleared to further improve the cascade therapeutic effect.More importantly,PIL had excellent photothermal conversion efficiency(37.35%)and manifested a surprising temperature rising effect in tumor.Taken together,the decreasing LA concentration,accumulation of high-toxic ROS,the depletion of GSH together with the higher intra-tumoral temperature potently enhanced in vivo antitumor therapy.Therefore,a promising therapeutic tactic based on PIL integrating endogenous LA consumption,chemodynamic therapy(CDT),and photothermal therapy(PTT)has been put forward.

Mesothelin targeted nano-system enhanced chemodynamic therapy and tirapazamine chemotherapy via lactate depletion

The enhanced permeability and retention(EPR)effect alone is not enough for nanoparticles to reach the target.Combination of active and passive targeting may be an effective drug delivery route.Hollow ferric-tannic acid complex nanocapsules(HFe-TA)may effectively degrade and release Fe^(2+) ions,Fe^(2+)ions induce the production of·OH,however,the fenton reaction needs amount of H_(2)O_(2)to enhance chemodynamic therapy.Due to their deficiencies,such nanoparticles cannot realize intravenous drug delivery.Here,the mesothelin-targeted membrane(MTM)was constructed to realize accurate delivery nano-system,mesothelin antibody was expressed on the 293T cell membrane to prepare a MTM.Lactate oxidase(Lox)was loaded on HFe-TA to obtain Lox@HFe-TA.Lox@HFe-TA was coated with MTM to develop the MTM nanosystem.Tirapazamine(TPZ)therapy also requires hypoxia circumstance.The MTM nanosystem combined with TPZ can significantly kill tumour cells and inhibit metastasis in vivo and in vitro.We also tested the biological safety of the treatment.In this study,we overcame the EPR defects via the MTM nanosystem,which can realize acute targeted delivery to the tumour site,lactate depletion,promoted reactive oxygen species(ROS)induction,enhanced the effect of TPZ,demonstrating a potential synergistic combination of cancer therapy with better efficacy and biosafety.

Effect of Catalase on Biocatalytic Synthesis of Pyruvate by Enzymes from Pseudomonas sp.

Pyruvate was produced from DL-lactate by a kind of green-chemical biocatalyst cell-free extract from bacterial strain Pseudomonas sp. SM-6. Catalase in cell-free extract, which could stabilize the pyruvate formed by lactate oxidase, played an important role in pyruvate preparation. The effect of catalase in conversion process was evaluated.

A metabolic intervention strategy to break evolutionary adaptability of tumor for reinforced immunotherapy

The typical hallmark of tumor evolution is metabolic dysregulation.In addition to secreting immunoregulatory metabolites,tumor cells and various immune cells display different metabolic pathways and plasticity.Harnessing the metabolic differences to reduce the tumor and immunosuppressive cells while enhancing the activity of positive immunoregulatory cells is a promising strategy.We develop a nanoplatform(CLCeMOF)based on cerium metal-organic framework(CeMOF)by lactate oxidase(LOX)modification and glutaminase inhibitor(CB839)loading.The cascade catalytic reactions induced by CLCeMOF generate reactive oxygen species“storm”to elicit immune responses.Meanwhile,LOX-mediated metabolite lactate exhaustion relieves the immunosuppressive tumor microenvironment,preparing the ground for intracellular regulation.Most noticeably,the immunometabolic checkpoint blockade therapy,as a result of glutamine antagonism,is exploited for overall cell mobilization.It is found that CLCeMOF inhibited glutamine metabolism-dependent cells(tumor cells,immunosuppressive cells,etc.),increased infiltration of dendritic cells,and especially reprogrammed CD8^(+)T lymphocytes with considerable metabolic flexibility toward a highly activated,long-lived,and memory-like phenotype.Such an idea intervenes both metabolite(lactate)and cellular metabolic pathway,which essentially alters overall cell fates toward the desired situation.Collectively,the metabolic intervention strategy is bound to break the evolutionary adaptability of tumors for reinforced immunotherapy.

Imaging resolution of biocatalytic activity using nanoscale scanning electrochemical microscopy

Scanning electrochemical microscopy represents a powerful tool for electro（chemical） characterization of surfaces, but its applicability has been limited in most cases at microscale spatial resolution, and the greatest challenge has been the scaling down to the nanoscale for fabrication and the use of nanometer-sized tips. Here, Pt nanoelectrodes with nanometer electroactive area were fabricated and employed for imaging a distribution of gold nanoparticles （AuNPs） and bioelectrocatalytic activity of a redox-active enzyme immobilized on gold surfaces.