DNAzyme@CuSNPs dual mimic enzyme probe-amplified chemiluminescent imaging array immunosensor for multiple chicken cytokines detection

The detection of cytokines plays an important role in clinical diagnosis and immune mechanism research of chicken diseases.In this work,a novel and ultrasensitive chemiluminescent(CL)imaging array immunosensor was proposed to detect multiple chicken cytokines based on DNAzyme@CuS nanoparticles(DNAzyme@CuSNPs)dual mimic enzyme signal amplification strategy.DNAzyme@CuSNPs owns excellent peroxidase property,which was modified with second antibody(Ab_(2))to prepare DNAzyme@CusNPs detection probe,and demonstrated high catalysis CL imaging signal due to synergistic catalysis.Chicken interleukin-4(ChIL-4)and chicken interferon-y(ChIFN-y)were used as model analysis samples,the DNAzyme@CusSNPs-based CL imaging immunosensor achieved simultaneous and high-throughput detection of ChIL-4 and ChIFN-y with wide linear range of 10^(-3)-10^(2) ng/mL,and the detection limits are 0.41 pg/mL and 0.36 pg/mL,respectively.The multiplex chicken cytokines CL imaging array immunosensor shows a high sensitivity,wide linear range,excellent specificity and acceptable stability.This research opens dual mimic enzyme signal-amplified strategy to develop sensitive CL imaging immunoassay for chicken diseases detection application.

Target-induced mimic enzyme deactivation based on mixed-node metal-organic frameworks for colorimetric assay of hydrogen sulfide

Accurate detection of hydrogen sulfide(H_(2)S)is of great significance for environmental monitoring and protection.We propose a colorimetric method for the detection of H_(2)S by the use of mixed-node Cu-Fe metal organic frameworks(Cu-Fe MOFs)as highly efficient mimic enzymes for target-induced deactivation.The Cu-Fe MOFs were synthesized by a simple solvothermal method and could catalyze the H_(2)O_(2)mediated oxidation of 3,30,5,50-tetramethylbenzidine(TMB)to oxTMB with a blue color.The presence of dissolved H_(2)S would deactivate the mimic enzymes,and then the blue color disappeared.The mechanism of the sensor was discussed by steady-state kinetic analysis.The designed assay was highly sensitive for H_(2)S detection with a linear range of 0à80 mmol/L and a detection limit of 1.6 mmol/L.Moreover,some potential substances in the water samples had no interference.This method with the advantages of low cost,high sensitivity,selectivity,and visual readout with the naked eye was successfully applied to the determination of H_(2)S in industrial wastewater samples.

Unveiling enzyme-mimetic active intermediate of a bioinspired oxo-MoS_(x) electrocatalyst for aqueous nitrate reduction

Excessive nitrate in groundwater has emerged as a serious environmental concern. The elevated nitrate concentration in drinking water causes a serious threat to public health on account of the possible transformation of nitrate to nitrite, which is one of the main predisposing factors of methemoglobinemia [1].

Ortho-Hydroxylation of Phenol by Tyrosinase Model Compounds

A series of tyrosinase model ligands and complexes containing polyimidazoles wereprepared. 2, 4-Di-tert-butyl-phenol was ortho-hydroxylated by the binuclear copper (?) complex[Cu2(6a)(CH3CN)2](ClO4)2 8a and molecular dioxygen under mild conditions with up to 80.4%yield, 91.4% selectivity and 92.0% conversion.

Nanozymes:Versatile Platforms for Cancer Diagnosis and Therapy

Natural enzymes usually suffer from high production cost,ease of denaturation and inactivation,and low yield,making them difficult to be broadly applicable.As an emerging type of artificial enzyme,nanozymes that combine the characteristics of nanomaterials and enzymes are promising alternatives.On the one hand,nanozymes have high enzyme-like catalytic activities to regulate biochemical reactions.On the other hand,nanozymes also inherit the properties of nanomaterials,which can ameliorate the shortcomings of natural enzymes and serve as versatile platforms for diverse applications.In this review,various nanozymes that mimic the catalytic activity of different enzymes are introduced.The achievements of nanozymes in different cancer diagnosis and treatment technologies are summarized by highlighting the advantages of nanozymes in these applications.Finally,future research directions in this rapidly developing field are outlooked.

Bifunctional nanozyme activities of layered double hydroxide derived Co-A1-Ce mixed metal oxides for antibacterial application

Marine biofouling is an expensive problem that needs evolved chemical or physical antifouling strategies.However,most of the current antifouling materials that would damage the environment through metal leaching and bacteria resistance are being halted.Nanozyme is one kind of environmental antifouling materials through generating reactive oxygen species(ROS).We prepared various contents of CeO2 that could uniform disperse compounding with Co3 O4 and CoAl2 O4 to form a stable Co-Al-Ce mixed metal oxide(MMO) by a layered double hydroxide derived method.We find that coupling with CeO2 can improve the peroxidase(POx) activity.When the molar ratio of Ce is 2.5% and the calcination temperature is 200℃,the POx activity of Co-Al-Ce MMO is the best caused by the good dispersion of catalytically active components and the high specific area(150.10±4.95 m2/g).This novel Co-Al-Ce MMO also exhibits an antibacterial mode of action Gram-negative bacteria in near-neutral pH solution through generating ROS(mainly ·O2-)in the presence of H2 O2.Ce containing MMO can be utilized as potential green marine antifouling material.

N,P,or S-doped carbon nanotubes as dual mimics of NADH oxidase and cytochrome c reductase

Most nanozyme research is limited to oxidase and peroxidase.Here,we reported the N,P,or S doped carbon nanotubes(CNTs)for enzyme mimics of nicotinamide adenine dinucleotide(NADH)oxidase and cytochrome c(Cyt c)reductase.Through the doping of N element,the NADH oxidase-like activity of CNTs is highly improved,the maximum initial velocity for N doped CNT(N-CNT)is increased by 4.28 times compared to that before the modification.Through the analysis of NADH oxidation products,we found that biologically active NAD+was produced,the oxygen was selectively reduced to water or hydrogen peroxide,which is consistent with natural NADH oxidase.Furthermore,we found for the first time that carbon nanotubes can promote the transfer of electrons from NADH to Cyt c,thereby can mimic the properties of Cyt c reductase.

Designed imidazole-based supramolecular catalysts for accelerating oxidation/hydrolysis cascade reactions

Reconstructing enzymatic active sites presents a significant challenge due to the intricacies involved in achieving enzyme-like scaffold folding and spatial arrangement of essential functional groups.There is also a growing interest in building biocatalytic networks,wherein multiple enzymatic active sites are localized within a single artificial system,allowing for cascaded transformations.In this work,we report the self-assembly of imidazole or its derivatives with fluorenylmethyloxycarbonyl-modified histidine and Cu2+to fabricate a supramolecular catalyst,which possesses catechol oxidase-like dicopper center with multiple imidazole as the coordination sphere.Transmission electron microscopy,low-temperature X-band continuous-wave electron paramagnetic resonance,K-edge X-ray absorption spectra/the extended X-ray absorption fine structure analysis,and density functional theory modeling were used for the structural characterization of the catalyst.The phenol derivatives and the dissolved oxygen were used as the substrates,with the addition of 4-aminoantipyrine to generate a red adduct with a maximum absorbance at 510 nm,for obtaining time-dependent absorbance change curves and estimating the activities.The results reveal that the addition of imidazole synergistically accelerates the oxidative activity about 10-fold and the hydrolysis activity about 14-fold than fluorenylmethyloxycarbonyl modified-histidine/Cu2+.The supramolecular nanoassembly also exhibits the ability to catalyze oxidation/hydrolysis cascade reactions,converting 2′,7′-dichlorofluorescin diacetate into 2′,7′-dichlorofluorescein.This process can be regulated through the methylation of the imidazole component at various positions.This work may contribute to the design of advanced biomimetic catalysts,and shed light on early structural models of the active sites of the primitive copper-dependent enzymes.

Cadmium sulfide as bifunctional mimics of NADH oxidase and cytochrome c reductase takes effect at physiological pH

Recently,a study of mimic enzyme has received more attentions.However,the investigation on the oxidoreductase activity of electron mediators in the biological respiratory chain is still rare.Herein,we found that cadmium sulfide(CdS)nanorods can catalyze the formation of superoxide anions.Due to the role of the photo-generated holes and the nicotinamide adenine dinucleotide(NADH)oxidation promoted by superoxide anion(O_(2)^(•−)),the CdS exhibits NADH oxidase-like activity and can be coupled with dehydrogenase to realize the recycling of NADH.It is worth mentioning that the bio-electron acceptor,cytochrome c(Cyt c),as a chromogenic substrate,can accept electrons transferred from O_(2)^(•−),which demonstrates the Cyt c reductase-like activity of CdS under physiological pH conditions.For different substrates,O_(2)^(•−)induced from CdS show oxidizing capacity for NADH and reducing capacity for Cyt c,which provides a new perspective for the in-depth study of new nanozyme.

Biomineralization-inspired copper-cystine nanoleaves capable of laccase-like catalysis for the colorimetric detection of epinephrine

Recently,many efforts have been dedicated to creating enzyme-mimicking catalysts to replace natural enzymes in practical fields.Inspired by the pathological biomineralization behaviour of L-cystine,in this study,we constructed a laccase-like catalyst through the co-assembly of L-cystine with Cu ions.Structural analysis revealed that the formed catalytic Cu-cystine nanoleaves(Cu-Cys NLs)possess a Cu(I)-Cu(II)electron transfer system similar to that in natural laccase.Reaction kinetic studies demonstrated that the catalyst follows the typical Michaelis-Menten model.Compared with natural laccase,the Cu-Cys NLs exhibit superior stability during long-term incubation under extreme pH,high-temperature or high-salt conditions.Remarkably,the Cu-Cys NLs could be easily recovered and still maintained 76%of their activity after 8 cycles.Finally,this laccase mimic was employed to develop a colorimetric method for epinephrine detection,which achieved a wider linear range(9–455μmol·L^(−1))and lower limit of detection(2.7μmol·L^(−1)).The Cu-Cys NLs also displayed excellent specificity and sensitivity towards epinephrine in a test based on urine samples.

Supramolecular Single-Chain Polymeric Nanoparticles

Nature has unparalleled control over the conforma-tion and dynamics of its folded macromolecular structures.Nature’s ability to arrange amino acids into a precise spatial organization by way of folding allows proteins to fulfill specific functions in an ex-tremely efficient manner.

Signal Amplification for Highly Sensitive Immunosensing

To dissolve the bottleneck problem of life and biomedical science in detection of biomolecules with low abundance and acquisition of ultraweak biological signals,highly sensitive analytical methods coupling with the specificity of biological recognition events have been quickly developed by the exploring of signal amplification strategies.These strategies have extensively been introduced into the development of highly sensitive immunosensing methods by combining with highly specific immunological recognition.They can be divided into two groups.One group of strategies attempts to transfer the immunological recognition event into large number of reporter probes or signal probes for signal readout by employing nano/micro-materials as vehicles for multi-labeling and/or molecular biological amplification for increasing the abundance of the signal molecules.The other uses nanomaterials or enzyme mimics as catalytic tools/tags to obtain enhanced detection signal.This review focuses on the significant advances in design of signal amplification strategies for highly sensitive immunosensing.