No abstract

An electrochemical biosensor, fabricated by immobilizing horseradish peroxidase onto dendritic mesoporous silica nanoparticles, is employed for living cell H2O2 detection.

No abstract

No abstract

1IntroductionDirect electron transfer (DET) of heme protein has been aresearch focus becauseitnot only establishes adesirable model for fundamental study of proteins in biological systems,but also plays asignificant role in fabricating mediator-free bioelectrochemicald evices,s uch as the third generation biosensors [1],b iofuel cells [2],e nzymatic bioreactors [3] and biomedical devices [4].H emoglobin (Hb) is ak ind of utmost important heme protein in red cells.I t has aq uaternary structurec ontaining four polypeptide chains (globin chains)a nd one heme group bound to each globin chain [5,6].D ue to its known structurea nd commercial availability,H bi sc onsidered as an ideal model molecule for heme protein study.U nfortunately, DET between Hb and electrodes urface is generally difficult becauset he redox-active center is embedded in its protein shelld eeply [7] and enzyme usually losesi ts bioactivity on the bare electrode [8].T of acilitate DET and retain the bioactivity of immobilizede nzyme,b iocompatible materials have been used to immobilize Hb,s uch as surfactants [9],b iopolymers [10],h ydrogels [11],p olyelectrolytes [12] and nano-materials [13].Considerable attentions have been paid to nano-materials due to their remarkable advantages includingh igh conductivity,h igh catalytic efficiency and excellentb iocompatibility.T hey will present favorable microenvironment to keep the activity of immobilizedp roteins and consequently to fabricate eligible biosensors.F or exam-ple,A un anoparticles (Au-NPs) can offer an attractive platformf or enzyme immobilization not only because of its excellent conductivitya nd biocompatibility but also because of its facile and robust interaction with various biomolecules containing thiol and disulfideg roups [14,15].B esides,m agnetic nanoparticles are also strong candidates in al argev ariety of applications. They are ideal bimolecular immobilizingc arriers and they enable quick and efficient isolation or extraction of at arget molecule or substance by an externalm agnetic field [16].T he most widely studied superparamagneticn anoparticles are magnetite (Fe 3 O 4 ). However, naked Fe 3 O 4 nanoparticles are very sensitive to oxidation and pronet oa ggregate [17].O ne of the maina pproaches to overcome these limitations is to protect naked magnetic NPs with metals [18].Abstract:S table magneticn anocomposite of gold nanoparticles (Au-NPs) decoratingF e 3 O 4 core was successfully synthesized by the linker of Boc-L-cysteine.T ransmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDX)a nd cyclic voltammograms (CV) were performedt oc haracterize the as-prepared Fe 3 O 4 @Au-Nps.T he results indicated that Au-Nps dispersed homogeneously around Fe 3 O 4 with the ratio of Au to Fe 3 O 4 nanoparticles as 5-10/1 andt he apparente lectrochemical area as 0.121 cm 2 .A fters elf-assembly of hemoglobin (Hb)o nF e 3 O 4 @Au-Npsb ye lectrostatic interaction,ahydrogen peroxide biosensor was developed. TheF e 3 O 4 @Au-Nps/Hbm odified GCE exhibited fast direct ele...