Synthesis and surface modification of uniform MFe2O4 (M = Fe, Mn, and Co) nanoparticles with tunable sizes and functionalities

Cabrera, Lourdes I.; Somoza, Álvaro; Marco, José F.; Serna, Carlos J.; Morales, M.P.

doi:10.1007/s11051-012-0873-x

Cited by 59 publications

(71 citation statements)

References 55 publications

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“…By changing the precursor concentration, the ratio between the surfactant and the precursor also varies. Several studies have shown that an increase in concentration may lead to both an increase 25,27,34,35 and a decrease 26,36 of the particle size. A conclusive explanation is still lacking.…”

Section: Introductionmentioning

confidence: 99%

“…We show that the ratio of the surfactant to the precursor plays a crucial role in tuning the size by changing the concentration, and we explain the observed opposite increasing/decreasing trend reported in the literature. [25][26][27]34,35 Iron oxide nanoparticles are superparamagnetic whose magnetic properties depend on their size. Magnetic measurements show that the nanoparticles possess room-temperature magnetizations close to the theoretically predicted values.…”

Section: Introductionmentioning

confidence: 99%

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Effect of precursor concentration on size evolution of iron oxide nanoparticles

et al. 2017

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Thermal decomposition is a promising route for the synthesis of magnetic nanoparticles. The simplicity of the synthesis method is counterbalanced by the complex chemistry of the system such as precursor decomposition and surfactant-reducing agent interactions. Control over nanoparticle size is achieved by adjusting the reaction parameters, namely, the precursor concentration. The results, however, are conflicting as both an increase and a decrease in nanoparticle size, as a function of increasing concentration, have been reported. Here, we address the issue of size-controlled synthesis via the precursor concentration. We synthesized iron oxide nanoparticles with sizes from 6 nm to 24 nm with narrow size distributions. We show that the size does not monotonically increase with increasing precursor concentration.After an initial increase, the size reaches a maximum and then shows a decrease with increasing precursor concentration. We argue that the observation of two different size regimes is closely related to the critical role of the amount of surfactant. We confirm the effect of surfactant amount on nucleation and growth and explain the observed trend. Furthermore, we show that the nanoparticles show size-dependent but superior superparamagnetic properties at room temperature.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of precursor concentration on size evolution of iron oxide nanoparticles

et al. 2017

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“…In this work, the concept of NP network formation using Hcp1_cys3 as a connecting unit is extended to magnetite NPs (Fe 3 O 4 NPs) and cobalt ferrite NPs (CoFe 2 O 4 NPs). The synthesis of magnetite NPs with a size of about 8 nm and the ligand exchange followed the protocol of Cabrera et al [ 36 ], with results as shown in the TEM images of Figure S4, Supporting Information File 1 . The water-dispersible, mercaptosuccinic acid stabilized Fe 3 O 4 NP solution was aligned in an external magnetic field parallel to the sample.…”

Section: Resultsmentioning

confidence: 99%

“…A third NP system demonstrates that our concept of the utilization of Hcp1_cys3 as a gluing unit between the NPs to fabricate a linear structure is universal. We synthesized cobalt ferrite NPs (CoFe 2 O 4 NPs) following the protocol of Cabrebra [ 36 ] and exchanged the oleic acid ligand to phosphonoacetic acid by the protocol of Lees [ 41 ] to disperse the NPs in water. The phosphonoacetic acid stabilized CoFe 2 O 4 NPs have a mean diameter of 5.5 nm as determined by TEM (Figure S7, Supporting Information File 1 ).…”

Section: Resultsmentioning

confidence: 99%

Hemolysin coregulated protein 1 as a molecular gluing unit for the assembly of nanoparticle hybrid structures

Pham¹,

Schreiber²,

Sturm³

et al. 2016

Beilstein J. Nanotechnol.

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SummaryHybrid nanoparticle (NP) structures containing organic building units such as polymers, peptides, DNA and proteins have great potential in biosensor and electronic applications. The nearly free modification of the polymer chain, the variation of the protein and DNA sequence and the implementation of functional moieties provide a great platform to create inorganic structures of different morphology, resulting in different optical and magnetic properties. Nevertheless, the design and modification of a protein structure with functional groups or sequences for the assembly of biohybrid materials is not trivial. This is mainly due to the sensitivity of its secondary, tertiary and quaternary structure to the changes in the interaction (e.g., hydrophobic, hydrophilic, electrostatic, chemical groups) between the protein subunits and the inorganic material. Here, we use hemolysin coregulated protein 1 (Hcp1) from Pseudomonas aeruginosa as a building and gluing unit for the formation of biohybrid structures by implementing cysteine anchoring points at defined positions on the protein rim (Hcp1_cys3). We successfully apply the Hcp1_cys3 gluing unit for the assembly of often linear, hybrid structures of plasmonic gold (Au NP), magnetite (Fe3O4 NP), and cobalt ferrite nanoparticles (CoFe2O4 NP). Furthermore, the assembly of Au NPs into linear structures using Hcp1_cys3 is investigated by UV–vis spectroscopy, TEM and cryo-TEM. One key parameter for the formation of Au NP assembly is the specific ionic strength in the mixture. The resulting network-like structure of Au NPs is characterized by Raman spectroscopy, showing surface-enhanced Raman scattering (SERS) by a factor of 8·104 and a stable secondary structure of the Hcp1_cys3 unit. In order to prove the catalytic performance of the gold hybrid structures, they are used as a catalyst in the reduction reaction of 4-nitrophenol showing similar catalytic activity as the pure Au NPs. To further extend the functionality of the Hcp1_cys3 gluing unit, Fe3O4 and CoFe2O4 NPs are aligned in a magnetic field and connected by utilization of cysteine-modified Hcp1. After lyophilization, a fiber-like material of micrometer scale length can be observed. The Fe3O4 Hcp1_cys3 fibers show superparamagnetic behavior with a decreasing blocking temperature and an increasing remanent magnetization leading to a higher squareness value of the hysteresis curve. Thus the Hcp1_cys3 unit is shown to be very versatile in the formation of new biohybrid materials with enhanced magnetic, catalytic and optical properties.

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“…Furthermore, in many cases, researchers combine ferrite with transition elements in order to enhance their structure which can lead to better lasting magnetic properties since ferrite alone might lose its magnetic properties during the process of degrading water contaminants. Many researchers have synthesized M x Fe 2-x O 4 where M is iron, cobalt, copper or another transition element and x = 0.1, 0.3, 0.7, 1.0 or any desired element ratios as a combination formula which is effective in degrading contaminants while retaining their magnetic properties for sufficient time (36).…”

Section: Nanostructured Ferritementioning

confidence: 99%