Molecular fluorescence significantly enhanced by gold nanoparticles@zeolitic imidazolate framework-8

Noble metal nanoparticles exhibit unique surface plasmon resonance dependent optical properties.On this basis,gold nanoparticles(AuNPs)encapsulated in metal–organic frameworks(MOFs)can form AuNPs@MOFs composites to modulate the optical properties of fluorescent molecules,which is less reported.In this paper,based on the fluorescence enhancement effect of AuNPs on 2-(2-hydroxyphenyl)-1H-benzimidazole(HPBI)molecules,zeolitic imidazolate framework-8(ZIF-8)crystals with structural stability were introduced.AuNPs@ZIF-8 exhibited a significantly pronounced fluorescence enhancement of the HPBI molecules.In addition,by comparing the fluorescence characteristics of the HPBI molecules adsorbed on AuNPs@ZIF-8 and those captured in AuNPs@ZIF-8,we found that the ZIF-8 can act as a spacer layer with highly effective near-field enhancement.All our preliminary results shed light on future research on the composite structures of noble metal particles and MOFs for fluorescent probes and sensing applications.

Preparation of ZIF-8@PEBAX/PVDF nanocomposite membrane by the combination of self-assembly and in-situ growth for removing thiophene from the model gasoline

Metal-organic frameworks(MOFs)have gained attention in the development of MOFs/polymer hybrid membranes for pervaporation.However,the agglomeration of MOFs particles and interfacial defects limit its further application.In this study,we present a novel approach to fabricate a ZIF-8@PEBAX/PVDF nanocomposite membrane for removing thiophene from the model gasoline by combination of selfassembly and in-situ growth.Firstly,a PVDF supporting membrane was modified to have a negative charge.Next,positively charged zinc ions were attracted onto the negatively charged PVDF supporting membrane through electrostatic interaction.Afterwards,the Zinc ions deposited PVDF membrane was immersed into dimethylimidazole solution to form a uniform ZIF-8 layer.Finally,the ZIF-8 layer was coated with poly(ether-block-amide)(PEBAX)using the pouring method.Experimental results showed that the separating efficiency of the ZIF-8@PEBAX/PVDF nanocomposite membrane was improved significantly compared to that of pristine PEBAX membrane.The optimal permeation flux and enrichment factor of membrane were 27.80 kg(m^(2)h)^(-1)and 6.9,respectively.

The accumulation and toxicity of ZIF-8 nanoparticles in Corbicula fluminea

Metal-organic frameworks(MOFs)are promising new materials that have been intensively studied and possibly applied to various environmental remediation.However,little is known about the fate and risk of MOFs to living organisms in thewater environment.Here,the toxic effects of ZIF-8 nanoparticles(NPs)on benthic organisms were confirmed by sub-chronic toxicity experiments(7 and 14 days)using Corbicula fluminea as the model organism.With exposure doses ranging from 0 to 50 mg/L,ZIF-8 NPs induced oxidative stress behaviors similar to the hormesis effect in the tissues of C.fluminea.The oxidative stress induced by ZIF-8 NPs and the released Zn^(2+)was the crucial cause of the toxic effects.Besides,we also found that the ZIF-8 NPs and dissolved Zn^(2+)may result in different mechanisms of toxicity and accumulation depending on the dosages.The Zn^(2+)release rate of ZIF-8NPswas high at low dosages,leading to a higher proportion of Zn^(2+)taken up by C.fluminea than the particulate ZIF-8.Conversely,at high dosages,C.fluminea mainly ingested the ZIF-8 NPs and resulted in increased mortality.The results have important implications for understanding the fate and biological effects of ZIF-8 in natural aquatic environments.

A novel structure of ultra-high-loading small moleculesencapsulated ZIF-8 colloid particles

The safety of nanoparticle-based drug delivery systems(DDSs)for cancer treatment is still a challenge,restricted by the intrinsic cytotoxicity of drug carriers and leakage of loaded drug.Here,we propose a novel nanocarrier’s cytotoxicity avoidance strategy by synthesizing an encapsulation core–shell structure of zeolitic imidazolate framework-8(ZIF-8)-based colloid particles(CPs)with an amorphous ZIF-8 skin.This encapsulation structure achieves an ultra-high loading rate(LR)of 90%(i.e.,9 mg doxorubicin(DOX)per 1 mg ZIF-8)for DOX and the protection of DOX from leaking.Notably,to deliver unit-dose drug,this ultra-high LR of 90%significantly reduces the usage of ZIF-8 to 1.2%(2 orders of magnitude)compared to that of DOX@ZIF-8 with a 10%LR,in which cytotoxicity of ZIF-8 could well below the safety limit and then be relatively ignored.Safety,drug delivery efficacy,scale-up ability,and universality of this encapsulation structure have been further verified.Our findings suggest the great potential of this ZIF-8-based encapsulation core–shell structure in the field of drug delivery.

High-performance Removal of Tetracycline Enabled by Fe^(0)Nanoparticles Supported on Carbon@ZIF-8

Significant concerns have been raised over the removal of antibiotics,such as tetracyclines(TC)in aquatic environments.Herein,we synthesized a new type of heterogeneous catalyst by supporting Fe^(0) nanopartciles(FeNPs)onto carbon coated ZIF-8(C@ZIF-8).The carbon layer formed by glucose was beneficial to maintain the morphology and porous structure of ZIF-8,which can also appropriately improve the hydrophobicity of ZIF-8 for enriching the TC.The as-prepared FeNPs-C@ZIF-8 catalyst featured an extreme large specific surface area(1122.16 m2/g),and the supported FeNPs with an average diameter of 6.13 nm exhibited a high dispersity on the supporting matrix of C@ZIF-8.For the removal of tetracycline,the large specific surface area of FeNPs-C@ZIF-8 allowed for an easy access of tetracycline to the FeNPs,while the highly dispersed FeNPs served as actived sites for the efficient degradation of tetracycline.A synergistic effect between adsorption and catalytic degradation of FeNPs(5%,mass fraction)-C@ZIF-8 was proven to be responsible for the high-performance removal of tetracycline with the removal efficiency high up to 93.02%at pH 5,25℃.The FeNPs-C@ZIF-8 was capable of recycling after activation with supplementary Fe^(0),which still maintained a high removal efficiency of 75.52%in the 5th cycle within 20 min.

pH响应性吡唑醚菌酯/沸石咪唑酯骨架材料纳米颗粒的制备及抑菌活性

沸石咪唑酯骨架材料(ZIF-8)稳定性好,比表面积大,纳米粒径可调,具有酸敏感性。为研究其在农药递送中作为缓控释载体的性能和应用,以吡唑醚菌酯(pyraclostrobin,以下简称Pyr)为模式农药,以二价锌为配位中心,二甲基咪唑为有机配体,采用“一锅法”制备了pH响应性吡唑醚菌酯控释剂Pyr@ZIF-8;通过扫描电子显微镜(SEM)、动态光散射激光粒度仪(DLS)、傅里叶红外光谱(FTIR)、X射线衍射(XRD)和热重分析(TGA)等物理手段对Pyr@ZIF-8的形貌、粒径和Zeta电位等进行了表征;采用高效液相色谱(HPLC)考察了其在紫外光源下的光解稳定性和不同pH值下的酸控释放性能;最后分别采用菌丝生长速率法和盆栽试验研究了其对油菜菌核病菌的抑制效果。结果表明:所制备的Pyr@ZIF-8的平均粒径为143.1 nm,载体ZIF-8对Pyr的负载率为10.8%;与Pyr原药相比,紫外光照下Pyr@ZIF-8中Pyr的降解率降低了6.2%;在pH值分别为4.0、6.0、8.0的环境下静置24 h,Pyr@ZIF-8中Pyr的释放率分别为88.1%±2.5%、67.3%±3.1%和25.6%±2.9%,表现出pH响应性释放性能;在0.1μg/mL质量浓度下,Pyr@ZIF-8对油菜菌核病菌的抑制效果比其乳油高16.4%(生长速率法)和9.4%(盆栽试验)。上述结果表明,所制备的纳米递送体系Pyr@ZIF-8不仅具有减缓吡唑醚菌酯光降解的作用,还有良好的酸控缓释和更高的抑菌效果。