ENZYME-LIKE ESTEROLYTIC ACTION OF ALGINATE-COBALT(Ⅱ)COMPLEX MEMBRANE

The investigation of the esterolysis of p-nitrophenol acetate (PNPA) catalyzed by alginate-cobalt(Ⅱ) complex membrane was carried out under various conditions. The results showed that the pseudo-first-order plots of the hydrolyses of PNPA catalyzed by alginate-Co(Ⅱ) complex membrane were linear. The kinetic constants were obtained and showed that the hydrolysis reactions obeyed Michaelis-Menten equations, showing an enzyme-like catalytic function of the membrane.

Emerging single-atom nanozymes for catalytic biomedical uses

The past four years have witnessed booming progress in single-atom nanozymes(SANs),one of the newest generations of nanozymes with atomically dispersed metal sites for catalytic biomedical uses.They show distinct advantages over their nanoparticle-based counterparts,such as well-defined electronic/geometric structures and complete atomic utilization efficiency,thus offering opportunities to develop advanced nanozymes for practical uses.The atomically dispersed active centers in SANs could also facilitate the precise regulation of catalytic performance,while probing structure–activity relationship for in-depth understanding of mechanism.In this review,we first introduce the synthetic approaches,surface engineering,and characterization techniques of SANs.Subsequently,we discuss the enzyme-like properties of SANs,including some strategies for boosting their catalytic activities.Furthermore,we present their biomedical applications,ranging from biosensors,antibacterial uses,antioxidants,to therapeutics.Finally,the challenges and opportunities of SANs are prospected.

Using silk-derived magnetic carbon nanocomposites as highly efficient Nanozymes and electromagnetic absorbing agents

Functional carbon nanomaterials have become the stars of many active research fields,such as electronics,energy,catalysis,imaging,sensing and biomedicine.Herein,a facile and one-pot strategy for generating ferromagnetic nanoparticles loaded on N-doped carbon nanosheets(Fe-N-CNS)is presented by salt-assisted high-temperature carbonization of natural silk proteins.Due to their graphitic structures,N-doping and ferromagnetic nanoparticles(FeN_(x),FeO_(y),FeC_(z)),the silk-derived Fe-N-CNS can act as excellent mimics of both peroxidase and oxidase.Benefiting from the combined character of the graphene-like structures and enzyme-like activities,Fe-N-CNS can be further applied to highly efficient dye removal via synergistic adsorption and degradation.Meanwhile,the as-prepared Fe-N-CNS with intrinsic magnetism and electrical conductivity can also serve as an efficient electromagnetic wave absorption agent.The broadest effective absorption bandwidth(EAB)of as-obtained absorbing material yields a 6.73 GHz with 1 mm thickness,with a maximum reflection loss of-37.33 dB(11.41 GHz).The EAB can cover2~18 GHz with a tunable absorber thickness from 1.0 mm to 5.0 mm.Collectively,Fe-N-CNS,as a dualfunctional material,can tackle the aggravating environmental pollution issues of both dyes and electromagnetic waves.

Single-atom nanozymes towards central nervous system diseases

Nanozymes have a similar catalytic mechanism to natural enzymes,with excellent performance,facile synthesis,and better stability.Single-atom nanozymes are developed based on single-atom catalysts due to their advantages in coordination structure and electronic configuration,making them highly enzymatic-like biomimetic catalysts.Central nervous system(CNS)diseases have become one of the biggest killers of human health because they are difficult to diagnose and treat,expensive,and result in serious illness.Single-atom nanozymes have been widely used for biomedical applications,especially in oxidative-stressinduced diseases and most CNS diseases which are closely related to oxidative stress.Therefore,single-atom nanozymes show promising application prospects for the treatment of CNS diseases.In addition,due to the outstanding material properties and sensitivity of single-atom nanozymes,they also exhibit great advantages in detecting various CNS disease markers for diagnosis.

Recent progress in single-atom nanozymes research

Single-atom nanozyme(SAzyme)is the hot topic of the current nanozyme research.Its intrinsic properties,such as high activity,stability,and low cost,present great substitutes to natural enzymes.Moreover,its fundamental characteristics,i.e.,maximized atom utilizations and well-defined geometric and electronic structures,lead to higher catalytic activities and specificity than traditional nanozymes.SAzymes have been applied in many biomedical areas,such as anti-tumor therapy,biosensing,antibiosis,and anti-oxidation therapy.Here,we will discuss a series of representative examples of SAzymes categorized by their biomedical applications in this review.In the end,we will address the future opportunities and challenges SAzymes facing in their designs and applications.

Nanozymes: created by learning from nature

Nanozymes,a type of nanomaterials with enzyme-like activity,have shown great potential to replace natural enzymes in many fields such as biochemical detection,environmental management and disease treatment.However,the catalytic efficiency and substrate specificity of nanozymes still need improvement.To further optimize the enzymatic properties of nanozymes,recent studies have introduced the structural characteristics of natural enzymes into the rational design of nanozymes,either by employing small molecules to mimic the cofactors of natural enzymes to boost nanozymes’catalytic potential,or by simulating the active center of natural enzymes to construct the nanostructure of nanozymes.This review introduces the commonly used bio-inspired strategies to create nanozymes,aiming at clarifying the current progress and bottlenecks.Advances and challenges focusing on the research of bio-inspired nanozymes are outlined to provide ideas for the de novo design of ideal nanozymes.

Carbon-based nanozymes for biomedical applications

Nanozymes are nanomaterials with enzyme-like properties that have attracted significant interest owing to their capability to address the limitations of traditional enzymes such as fragility,high cost,and impossible mass production.Over the past decade,a broad variety of nanomaterials have been found to mimic the enzyme-like activity by engineering the active centers of natural enzymes or developing multivalent elements within nanostructures.Carbon nanomaterials with well-defined electronic and geometric structures have served as favorable surrogates of traditional enzymes by mimicking the highly evolved catalytic center of natural enzymes.In particular,by combining the unique electronic,optical,thermal,and mechanical properties,carbon nanomaterials-based nanozymes can offer a variety of multifunctional platforms for biomedical applications.In this review,we will introduce the enzymatic characteristics and recent advances of carbon nanozymes,and summarize their significant applications in biomedicine.