Lignocellulose has the potential to become a bio-based adsorbent due to its biodegradability and renewability.In this study,a novel polydopamine functionalized-lignin(lignin@PDA),prepared via self-polymerization of do...Lignocellulose has the potential to become a bio-based adsorbent due to its biodegradability and renewability.In this study,a novel polydopamine functionalized-lignin(lignin@PDA),prepared via self-polymerization of dopamine(PDA)on lignin,was used as a bio-based adsorbent for rapid scavenging of hexavalent chromium(Cr(VI)).The morphology,functional groups,crystalline structure,and chemical composition of lignin@PDA were characterized with a scanning electron microscope-energy dispersive spectrometer,Fourier transform infrared spectroscopy,X-ray diffraction,and X-ray photoelectron spectroscopy.The Cr(VI)adsorption process of lignin@PDA was studied using batch experiments as a function of pH,ionic strength,adsorbent dose,and contact time at room temperature.The adsorption rate of lignin@PDA was five times greater than that of the unmodified lignin,with a maximum adsorption capacity of 102.6 mg/g in an acidic medium.The adsorption of Cr(VI)on lignin@PDA fit the pseudo-secondorder equation and the Freundlich model,indicating that the adsorption process was mainly dominated by chemisorption and surface complexation.The thermodynamic parameters showed that adsorption of Cr(VI)on lignin@PDA was an endothermic and spontaneous process.The X-ray absorption fine structure results showed that sorption and reduction of Cr(VI)into Cr(II)occurred simultaneously on lignin.Moreover,PDA coating not only improved the reactivity of lignin but also promoted the complete reduction of Cr(VI)by lignin.According to these results,polydopamine functionalized-lignin is a promising bio-based adsorbent for immobilization of Cr(VI)from wastewater.展开更多
Amultifunctional liposomal polydopamine nanoparticle(MPM@Lipo)was designed in this study,to combine chemotherapy,photothermal therapy(PTT)and oxygen enrichment to clear hyperproliferating inflammatory cells and improv...Amultifunctional liposomal polydopamine nanoparticle(MPM@Lipo)was designed in this study,to combine chemotherapy,photothermal therapy(PTT)and oxygen enrichment to clear hyperproliferating inflammatory cells and improve the hypoxic microenvironment for rheumatoid arthritis(RA)treatment.MPM@Lipo significantly scavenged intracellular reactive oxygen species and relieved joint hypoxia,thus contributing to the repolarization of M1 macrophages into M2 phenotype.Furthermore,MPM@Lipo could accumulate at inflammatory joints,inhibit the production of inflammatory factors,and protect cartilage in vivo,effectively alleviating RA progression in a rat adjuvant-induced arthritis model.Moreover,upon laser irradiation,MPM@Lipo can elevate the temperature to not only significantly obliterate excessively proliferating inflammatory cells but also accelerate the production of methotrexate and oxygen,resulting in excellent RA treatment effects.Overall,the use of synergistic chemotherapy/PTT/oxygen enrichment therapy to treat RA is a powerful potential strategy.展开更多
Simple yet efficient detection methods for food allergens are in urgent need to help people avoid the risks imposed by allergenic food.In this work,a polydopamine(PDA)-based fluorescent aptasensor was developed to det...Simple yet efficient detection methods for food allergens are in urgent need to help people avoid the risks imposed by allergenic food.In this work,a polydopamine(PDA)-based fluorescent aptasensor was developed to detect arginine kinase(AK),one of the major allergens in shellfish.The aptamer towards AK was firstly selected via systematic evolution of ligands by exponential enrichment method and labeled with fluorescein amidite(FAM)to build a fluorescence resonance energy transfer(FRET)system with PDA particles.Polyethylene glycol(PEG)was employed to construct an antifouling surface for the aptasensor to eliminate food matrix interferences.With the presence of AK,the PDA-based aptasensor exhibited elevated fluorescent signals as the FAM-labeled aptamer bound to AK and detached from the PDA particles.The aptasensor showed great stability and resistance to nonspecific interference of background proteins and had a limit of detection(LOD)of 0.298μg/mL.The proposed aptasensor was further proved to be feasible for quantitative analysis of AK in nine species of shrimps and five commercial processed products,which indicated its high potential in tracing the presence of AK in complex aquatic products.展开更多
Magnesium(Mg) alloys are well-known in biomedical materials owing to their elastic module near to bone, biocompatibility and biodegradation properties. Nevertheless, poor corrosion resistance hinders their biomedical ...Magnesium(Mg) alloys are well-known in biomedical materials owing to their elastic module near to bone, biocompatibility and biodegradation properties. Nevertheless, poor corrosion resistance hinders their biomedical applications. Besides, it is necessary to endow Mg alloys with bioactive property, which is crucial for temporary bone implants. Here, a self-healing, corrosion resistant and bioactive duplex coating of plasma electrolytic oxidization(PEO)/polydopamine(PDA) is applied on AZ91 substrate using PEO and subsequent electrodeposition process. Moreover, the role of different electrodeposition times(60 s, 120 s) and dopamine concentrations(1 and 1.5 mg/ml) to improve corrosion resistance, bioactivity, biocompatibility and self-healing property and its mechanism are investigated. The results indicate that the PEO coating is efficiently sealed by the PDA, depending on the electrodeposition parameters. Noticeably, electrodeposition for 120 s in dopamine concentration of 1 mg/ml(120T-1C) results in the formation of uniform and crack-free PDA coating. Duplex PEO/PDA coatings reveal high bioactivity compared to PEO coating, owing to electrostatic interaction between PDA top-layer and calcium and phosphate ions as well as high hydrophilicity of coatings. In addition, duplex PEO/PDA coatings also show improved and more stable protective performance than the PEO and bare alloy, depending on the PDA deposition parameters. Noticeably, the corrosion current density of the 120T-1C decreases one orders of magnitude compared to PEO. In addition, the presence of a broad passivation region in the anodic polarization branch shows durable self-healing property via Zipper-like mechanism, demonstrating the duplex coating could preserve promising corrosion resistance.Furthermore, the cytocompatibility of duplex coated samples is also confirmed via interaction with MG63 cells. In summary, the PEO/PDA coating with great corrosion protection, self-healing ability, bioactivity and biocompatibility could be a promising candidate for degradable magnesium-based implants.展开更多
The combination of photothermal therapywith chemotherapy has gradually developed into promising cancer therapy.Here,a synergistic photothermal-chemotherapy nanoplatform based on polydopamine(PDA)-coated gold nanoparti...The combination of photothermal therapywith chemotherapy has gradually developed into promising cancer therapy.Here,a synergistic photothermal-chemotherapy nanoplatform based on polydopamine(PDA)-coated gold nanoparticles(AuNPs)were facilely achieved via the in situ polymerization of dopamine(DA)on the surface of AuNPs.This nanoplatform exhibited augmented photothermal conversion efficiency and enhanced colloidal stability in comparison with uncoated PDA shell AuNPs.The i-motif DNA nanostructure was assembled on PDA-coated AuNPs,which could be transformed into a C-quadruplex structure under an acidic environment,showing a characteristic pH response.The PDA shell served as a linker between the AuNPs and the i-motif DNA nanostructure.To enhance the specific cellular uptake,the AS1411 aptamer was introduced to the DNA nanostructure employed as a targeting ligand.In addition,Dox-loaded NPs(DAu@PDA-AS141)showed the pH/photothermal-responsive release of Dox.The photothermal effect of DAu@PDA-AS141 elicited excellent photothermal performance and efficient cancer cell inhibition under 808 nm near-infrared(NIR)irradiation.Overall,these results demonstrate that the DAu@PDA-AS141 nanoplatform shows great potential in synergistic photothermal-chemotherapy.展开更多
[Objectives]The paper was to prepare immunoadjuvant nanoparticles with good photothermal conversion efficiency and to achieve the synergistic antitumor effect of phototherapy and immunotherapy.[Methods]Poly(lactic-co-...[Objectives]The paper was to prepare immunoadjuvant nanoparticles with good photothermal conversion efficiency and to achieve the synergistic antitumor effect of phototherapy and immunotherapy.[Methods]Poly(lactic-co-glycolic acid)(PLGA)nanoparticles of imiquimod(R837)were prepared by emulsified solvent evaporation method.Dopamine was oxidized and self-polymerized to form polydopamine(PDA)under alkaline conditions,which then adhered to the surface of R837-PNPs(PDA-R837-PNPs).Particle size,Zeta potential and photothermal conversion capacity were used as indicators to select the best polymerization conditions.The photothermal conversion properties and photothermal stability of nanoparticles were investigated by near-infrared light(NIR)irradiation;the encapsulation efficiency and drug loading capacity of R837 were determined by HPLC;the cytotoxicity and cellular uptake of PDA-R837-PNPs were preliminarily investigated using 4T1 cells.[Results]PDA-R837-PNPs were prepared successfully.The optimal polymerization conditions were 0.5 mg/mL dopamine,3 h reaction time and 1.8 mg/mL R837-PNPs.The particle size of PDA-R837-PNPs was(186.7±4.81)nm;the PDI was 0.17±0.02;the Zeta potential was(-21.6±0.56)mV;the encapsulation efficiency was(58.02±0.04)%;and the drug loading capacity was(1.42±0.05)%.PDA-R837-PNPs had good photothermal conversion and photothermal stability in vitro.Cell experiments showed that PDA coating could significantly improve the celluar uptake of PNPs without obvious cytotoxicity,and PDA-R837-PNPs could produce heat to effectively kill 4T1 cells after NIR irradiation.[Conclusions]PDA-R837-PNPs have the characteristics of uniform particle size,good photothermal conversion effect and high cellular uptake rate,thus is expected to achieve efficient antitumor photoimmunotherapic effect.展开更多
Boron is an ambitious fuel in energetic materials since its high heat release values,but its application is prohibited by low combustion efficiency and oxidization during storage.The polydopamine(PDA)was introduced in...Boron is an ambitious fuel in energetic materials since its high heat release values,but its application is prohibited by low combustion efficiency and oxidization during storage.The polydopamine(PDA)was introduced into boron particles,investigating the impact of PDA content on the energetic behavior of boron.The results indicated that the PDA coating formed a fishing net structure on the surface of boron particles.The heat release results showed that the combustion calorific value of B@PDA was higher than that of the raw boron.Specifically,the actual combustion heat of boron powder in B@10%PDA increased by 38.08%.Meanwhile,the DSC peak temperature decreased by 100.65℃under similar oxidation rate compared to raw boron.Simultaneously,the B@PDA@AP and B@AP composites were prepared,and their combustion properties were evaluated.It was demonstrated that B@10%PDA@AP exhibited superior performance in terms of peak pressure and burning time,respectively.The peak pressure is 12.43 kPa more than B@AP and burning time is 2.22 times higher than B@AP.Therefore,the coating of PDA effectively inhibits the oxidization of boron during storage and enhances the energetic behavior of boron and corresponding composites.展开更多
The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate...The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.展开更多
The pyrolysis under inert atmosphere has been widely used for the synthesis of metal containing heteroatoms doped carbon materials, versatile catalysts for various reactions. However, it is difficult to prevent metal ...The pyrolysis under inert atmosphere has been widely used for the synthesis of metal containing heteroatoms doped carbon materials, versatile catalysts for various reactions. However, it is difficult to prevent metal nanoparticles aggregation during pyrolysis process. Herein, we reported the efficient synthesis of nitrogen doped carbon hollow nanospheres with cobalt nanoparticles （Co NP, ca. 10nm in size） distributed uniformly in the shell via pyrolysis of yolk-shell structured Zn-Co-ZIFs@polydopamine （PDA）. PDA acted as both protection layer and carbon source, which successfully prevented the aggregation of cobalt nanoparticles during high-temperature pyrolysis process. The Co NP and N containing carbon （Co NP/NC） hollow nanospheres were active for both oxygen evolution reaction （OER） and oxygen reduction reaction （ORR）, affording overpotential of 430 mV at 10 mA/cm2 for OER in 1 M KOH and comparable half-wave potential to that of Pt/C （0.80V vs RHE） for ORR in 0.1 M KOH. The superior performance of carbon hollow nanospheres for both OER and ORR was mainly attributed to its small metal nanoparticles, N-doping and hollow nanostructure. The protection and confinement effect that originated from PDA coating strategy could be extended to the synthesis of other hollow structured carbon materials, especially the ones with small metal nanoparticles.展开更多
基金supported by the Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ19E030017)the Research Start-up Fund(Grant No.KYS205619042)the Technological Research Project for Public Welfare of Zhejiang Province(Grant No.LGG19E030005).
文摘Lignocellulose has the potential to become a bio-based adsorbent due to its biodegradability and renewability.In this study,a novel polydopamine functionalized-lignin(lignin@PDA),prepared via self-polymerization of dopamine(PDA)on lignin,was used as a bio-based adsorbent for rapid scavenging of hexavalent chromium(Cr(VI)).The morphology,functional groups,crystalline structure,and chemical composition of lignin@PDA were characterized with a scanning electron microscope-energy dispersive spectrometer,Fourier transform infrared spectroscopy,X-ray diffraction,and X-ray photoelectron spectroscopy.The Cr(VI)adsorption process of lignin@PDA was studied using batch experiments as a function of pH,ionic strength,adsorbent dose,and contact time at room temperature.The adsorption rate of lignin@PDA was five times greater than that of the unmodified lignin,with a maximum adsorption capacity of 102.6 mg/g in an acidic medium.The adsorption of Cr(VI)on lignin@PDA fit the pseudo-secondorder equation and the Freundlich model,indicating that the adsorption process was mainly dominated by chemisorption and surface complexation.The thermodynamic parameters showed that adsorption of Cr(VI)on lignin@PDA was an endothermic and spontaneous process.The X-ray absorption fine structure results showed that sorption and reduction of Cr(VI)into Cr(II)occurred simultaneously on lignin.Moreover,PDA coating not only improved the reactivity of lignin but also promoted the complete reduction of Cr(VI)by lignin.According to these results,polydopamine functionalized-lignin is a promising bio-based adsorbent for immobilization of Cr(VI)from wastewater.
文摘Amultifunctional liposomal polydopamine nanoparticle(MPM@Lipo)was designed in this study,to combine chemotherapy,photothermal therapy(PTT)and oxygen enrichment to clear hyperproliferating inflammatory cells and improve the hypoxic microenvironment for rheumatoid arthritis(RA)treatment.MPM@Lipo significantly scavenged intracellular reactive oxygen species and relieved joint hypoxia,thus contributing to the repolarization of M1 macrophages into M2 phenotype.Furthermore,MPM@Lipo could accumulate at inflammatory joints,inhibit the production of inflammatory factors,and protect cartilage in vivo,effectively alleviating RA progression in a rat adjuvant-induced arthritis model.Moreover,upon laser irradiation,MPM@Lipo can elevate the temperature to not only significantly obliterate excessively proliferating inflammatory cells but also accelerate the production of methotrexate and oxygen,resulting in excellent RA treatment effects.Overall,the use of synergistic chemotherapy/PTT/oxygen enrichment therapy to treat RA is a powerful potential strategy.
基金financially supported by the National Key R&D Program of China(2019YFC1605002)the National Natural Science Foundation of China(31871735)Xinmiao Talent Project of Zhejiang Province(2019R408063)。
文摘Simple yet efficient detection methods for food allergens are in urgent need to help people avoid the risks imposed by allergenic food.In this work,a polydopamine(PDA)-based fluorescent aptasensor was developed to detect arginine kinase(AK),one of the major allergens in shellfish.The aptamer towards AK was firstly selected via systematic evolution of ligands by exponential enrichment method and labeled with fluorescein amidite(FAM)to build a fluorescence resonance energy transfer(FRET)system with PDA particles.Polyethylene glycol(PEG)was employed to construct an antifouling surface for the aptasensor to eliminate food matrix interferences.With the presence of AK,the PDA-based aptasensor exhibited elevated fluorescent signals as the FAM-labeled aptamer bound to AK and detached from the PDA particles.The aptasensor showed great stability and resistance to nonspecific interference of background proteins and had a limit of detection(LOD)of 0.298μg/mL.The proposed aptasensor was further proved to be feasible for quantitative analysis of AK in nine species of shrimps and five commercial processed products,which indicated its high potential in tracing the presence of AK in complex aquatic products.
文摘Magnesium(Mg) alloys are well-known in biomedical materials owing to their elastic module near to bone, biocompatibility and biodegradation properties. Nevertheless, poor corrosion resistance hinders their biomedical applications. Besides, it is necessary to endow Mg alloys with bioactive property, which is crucial for temporary bone implants. Here, a self-healing, corrosion resistant and bioactive duplex coating of plasma electrolytic oxidization(PEO)/polydopamine(PDA) is applied on AZ91 substrate using PEO and subsequent electrodeposition process. Moreover, the role of different electrodeposition times(60 s, 120 s) and dopamine concentrations(1 and 1.5 mg/ml) to improve corrosion resistance, bioactivity, biocompatibility and self-healing property and its mechanism are investigated. The results indicate that the PEO coating is efficiently sealed by the PDA, depending on the electrodeposition parameters. Noticeably, electrodeposition for 120 s in dopamine concentration of 1 mg/ml(120T-1C) results in the formation of uniform and crack-free PDA coating. Duplex PEO/PDA coatings reveal high bioactivity compared to PEO coating, owing to electrostatic interaction between PDA top-layer and calcium and phosphate ions as well as high hydrophilicity of coatings. In addition, duplex PEO/PDA coatings also show improved and more stable protective performance than the PEO and bare alloy, depending on the PDA deposition parameters. Noticeably, the corrosion current density of the 120T-1C decreases one orders of magnitude compared to PEO. In addition, the presence of a broad passivation region in the anodic polarization branch shows durable self-healing property via Zipper-like mechanism, demonstrating the duplex coating could preserve promising corrosion resistance.Furthermore, the cytocompatibility of duplex coated samples is also confirmed via interaction with MG63 cells. In summary, the PEO/PDA coating with great corrosion protection, self-healing ability, bioactivity and biocompatibility could be a promising candidate for degradable magnesium-based implants.
基金This work was financially supported by National Natural Sciences Foundation of China(31971308 and 82102767)National S&T Major Project(2019ZX09301-147)+1 种基金Sichuan Science and Technology Program(2021YFS0081)Luzhou Science and Technology Plan(2018CDLZ-10).
文摘The combination of photothermal therapywith chemotherapy has gradually developed into promising cancer therapy.Here,a synergistic photothermal-chemotherapy nanoplatform based on polydopamine(PDA)-coated gold nanoparticles(AuNPs)were facilely achieved via the in situ polymerization of dopamine(DA)on the surface of AuNPs.This nanoplatform exhibited augmented photothermal conversion efficiency and enhanced colloidal stability in comparison with uncoated PDA shell AuNPs.The i-motif DNA nanostructure was assembled on PDA-coated AuNPs,which could be transformed into a C-quadruplex structure under an acidic environment,showing a characteristic pH response.The PDA shell served as a linker between the AuNPs and the i-motif DNA nanostructure.To enhance the specific cellular uptake,the AS1411 aptamer was introduced to the DNA nanostructure employed as a targeting ligand.In addition,Dox-loaded NPs(DAu@PDA-AS141)showed the pH/photothermal-responsive release of Dox.The photothermal effect of DAu@PDA-AS141 elicited excellent photothermal performance and efficient cancer cell inhibition under 808 nm near-infrared(NIR)irradiation.Overall,these results demonstrate that the DAu@PDA-AS141 nanoplatform shows great potential in synergistic photothermal-chemotherapy.
基金Supported by National Natural Science Foundation of China(82003683)Fundamental Research Funds for the Central Universities of Southwest Minzu University(2021105)。
文摘[Objectives]The paper was to prepare immunoadjuvant nanoparticles with good photothermal conversion efficiency and to achieve the synergistic antitumor effect of phototherapy and immunotherapy.[Methods]Poly(lactic-co-glycolic acid)(PLGA)nanoparticles of imiquimod(R837)were prepared by emulsified solvent evaporation method.Dopamine was oxidized and self-polymerized to form polydopamine(PDA)under alkaline conditions,which then adhered to the surface of R837-PNPs(PDA-R837-PNPs).Particle size,Zeta potential and photothermal conversion capacity were used as indicators to select the best polymerization conditions.The photothermal conversion properties and photothermal stability of nanoparticles were investigated by near-infrared light(NIR)irradiation;the encapsulation efficiency and drug loading capacity of R837 were determined by HPLC;the cytotoxicity and cellular uptake of PDA-R837-PNPs were preliminarily investigated using 4T1 cells.[Results]PDA-R837-PNPs were prepared successfully.The optimal polymerization conditions were 0.5 mg/mL dopamine,3 h reaction time and 1.8 mg/mL R837-PNPs.The particle size of PDA-R837-PNPs was(186.7±4.81)nm;the PDI was 0.17±0.02;the Zeta potential was(-21.6±0.56)mV;the encapsulation efficiency was(58.02±0.04)%;and the drug loading capacity was(1.42±0.05)%.PDA-R837-PNPs had good photothermal conversion and photothermal stability in vitro.Cell experiments showed that PDA coating could significantly improve the celluar uptake of PNPs without obvious cytotoxicity,and PDA-R837-PNPs could produce heat to effectively kill 4T1 cells after NIR irradiation.[Conclusions]PDA-R837-PNPs have the characteristics of uniform particle size,good photothermal conversion effect and high cellular uptake rate,thus is expected to achieve efficient antitumor photoimmunotherapic effect.
文摘Boron is an ambitious fuel in energetic materials since its high heat release values,but its application is prohibited by low combustion efficiency and oxidization during storage.The polydopamine(PDA)was introduced into boron particles,investigating the impact of PDA content on the energetic behavior of boron.The results indicated that the PDA coating formed a fishing net structure on the surface of boron particles.The heat release results showed that the combustion calorific value of B@PDA was higher than that of the raw boron.Specifically,the actual combustion heat of boron powder in B@10%PDA increased by 38.08%.Meanwhile,the DSC peak temperature decreased by 100.65℃under similar oxidation rate compared to raw boron.Simultaneously,the B@PDA@AP and B@AP composites were prepared,and their combustion properties were evaluated.It was demonstrated that B@10%PDA@AP exhibited superior performance in terms of peak pressure and burning time,respectively.The peak pressure is 12.43 kPa more than B@AP and burning time is 2.22 times higher than B@AP.Therefore,the coating of PDA effectively inhibits the oxidization of boron during storage and enhances the energetic behavior of boron and corresponding composites.
基金the support of the instrument and equipment fund of the Key Laboratory of Special Energy,Ministry of Education,Nanjing University of Science and Technology,China.
文摘The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.
文摘The pyrolysis under inert atmosphere has been widely used for the synthesis of metal containing heteroatoms doped carbon materials, versatile catalysts for various reactions. However, it is difficult to prevent metal nanoparticles aggregation during pyrolysis process. Herein, we reported the efficient synthesis of nitrogen doped carbon hollow nanospheres with cobalt nanoparticles （Co NP, ca. 10nm in size） distributed uniformly in the shell via pyrolysis of yolk-shell structured Zn-Co-ZIFs@polydopamine （PDA）. PDA acted as both protection layer and carbon source, which successfully prevented the aggregation of cobalt nanoparticles during high-temperature pyrolysis process. The Co NP and N containing carbon （Co NP/NC） hollow nanospheres were active for both oxygen evolution reaction （OER） and oxygen reduction reaction （ORR）, affording overpotential of 430 mV at 10 mA/cm2 for OER in 1 M KOH and comparable half-wave potential to that of Pt/C （0.80V vs RHE） for ORR in 0.1 M KOH. The superior performance of carbon hollow nanospheres for both OER and ORR was mainly attributed to its small metal nanoparticles, N-doping and hollow nanostructure. The protection and confinement effect that originated from PDA coating strategy could be extended to the synthesis of other hollow structured carbon materials, especially the ones with small metal nanoparticles.
