基于适配体亲和磁珠的黄曲霉毒素B_1单样本前处理试剂盒的制备及应用

黄曲霉毒素B_1(aflatoxin B_1,AFB_1)适配体共价偶联于磁珠表面制备适配体亲和磁珠(aptamer affinity magnetic beads,AAMB),将AAMB、孵育液、洗涤液和洗脱液预封装于试剂条中开发了AFB_1单样本前处理试剂盒,借助真菌毒素全自动净化仪实现了AFB_1前处理的自动化,使用超高效液相色谱仪对洗脱液中AFB_1的含量进行测定。通过优化磁珠粒径、适配体间接臂长度、适配体亲和磁珠用量、孵育液体积确定了AAMB的制备条件以及AFB_1单样本前处理试剂盒的使用条件,对比了手动和自动两种前处理方式下AAMB回收率的差异。在优化条件下,AFB_1的检出限(limit of detection,LOD)为0.6 ng/mL,玉米和小麦中低、中、高三个水平的加标回收率在92.8%~110.1%之间,日内精密度的相对标准偏差(relative standard deviation,RSD)小于5.1%,日间精密度的RSD为6.7%,具有良好的灵敏度、准确性和重复性;粮油基质(玉米、糙米、花生油和花生酱)中AFB_1成分国家有证标准物质的测定结果在其扩展范围内,具有良好的基质适用性。开发的单样本前处理试剂盒借助真菌毒素全自动净化仪仅需一步操作即可在20 min内自动完成10个样品的前处理,具有时间短、通量高、批次间差异小的优点,在真菌毒素定量检测方面具有良好的应用前景,为开发针对其它靶标的自动化前处理方法奠定了基础。

Fe/Co-based nanoparticles encapsulated in heteroatom-doped carbon electrocatalysts for oxygen reduction reaction

It is crucial to develop low-cost and highly efficient catalysts for oxygen reduction reaction(ORR)which is the key process in electrochemical energy conversion and storage devices.Transition metal-based nanoparticles/carbon materials are an important class of non-noble metal catalysts that have attracted considerable research interest.The topic of this review is mainly focused on carbon encapsulated Fe/Cobased nanoparticles catalysts for ORR,and these catalysts are summarized in categories of metals,oxides,carbides,phosphides,sulfides and hybrid nanoparticles.The structures and morphologies of the carbon matrix as well as compositions of nanoparticles have great influence on the catalytic performance.Numerous catalysts display excellent ORR activity and stability in alkaline media but only a few are efficient in acidic media.In addition,challenges and further strategies on the development of this type of carbon encapsulated nanoparticles catalysts are also proposed.

Encapsulated FeP nanoparticles with in-situ formed P-doped graphene layers:Boosting activity in oxygen reduction reaction

Nonprecious metal-based oxygen reduction reaction(ORR)electrocatalysts with high efficiency in both alkaline and acidic media are being intensively studied for the purpose of replacing expensive Pt-based catalysts;however,it is still a challenge to achieve superior ORR performances,especially in acidic media.Herein,by pyrolysis of mixed precursors of diammonium phosphate,melamine and hemin,we prepared a nanocomposite catalyst(denoted as FeP@PGL)composed of nitrogen-doped carbon nanosheets with embedded FeP nanoparticles(NPs),which were encapsulated by in-situ formed phosphorus-doped graphene layers.It is found that phosphorous was preferentially doped in the coating layers on FeP NPs,instead of in the carbon nanosheets.The FeP@PGL catalyst exhibited excellent ORR performance,with the onset and half-wave potential up to 1.01 and 0.90 V vs.the reversible hydrogen electrode(RHE)in alkaline media,and0.95 and 0.81 V vs.RHE in acidic media,respectively.By thorough microscopy and spectroscopy characterizations,the interfacial charge transfer between the encapsulated FeP NPs and P-doped graphene layers was identified,and the local work function of the catalyst surface was also reduced by the interfacial interaction.The interfacial synergy between the encapsulated FeP and phosphorus-doped graphene layers was essential to enhance the ORR performance.This study not only demonstrates the promising ORR properties of the encapsulated-FeP-based nanocomposite catalyst,but also provides direct evidence of the interfacial charge transfer effect and its role in ORR process.