Determination of the Size of Water-Soluble Nanoparticles and Quantum Dots by Field-Flow Fractionation

Abstract

Field flow fractionation (FFF) technique is used to determine the size of water-soluble Au, ZnS, ZnS-Mn2+ nanoparticles, and CdSe, CdSe-DNA quantum dots (QDs). The results of the FFF measurements are compared with the particle size analysis using conventional techniques like scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) studies. Water-soluble gold nanoparticles (AuNPs) stabilized by mercaptosuccinic acid (MSA) as the ligand when analyzed by the SEM and DLS showed evidence of extensive aggregation, preventing an accurate determination of the average particle size. The TEM analyses without staining offered a facile measurement of the nanoparticle core but average particle size determination required analysis of the TEM image using image analysis software. On the other hand the FFF is seemingly a convenient and easy method for the determination of the average particle size of the AuNPs. In case of the ZnS and ZnS-Mn2+ nanoparticles with mercaptopropionic acid (MPA) as the capping agent severe aggregation prevented accurate estimation of particle sizes even by the high resolution TEM (HRTEM), where as the size determination by the FFF was very facile. Analysis of the CdSe-DNA conjugate by the TEM was difficult as the sample got damaged upon exposure to the electron beam. The FFF cross-flow condition is apparently noninvasive and hence the technique was very effective in characterizing the CdSe-DNA QDs. Furthermore, using this simple technique it was possible to fractionate a sample of the AuNPs. The FFF measurement of water-soluble nanoparticles is an excellent complement to characterization of such particles by the conventional tools.

Using FlFFF and aTEM to determine trace metal–nanoparticle associations in riverbed sediment

“…This combination of FlFFF and aTEM, therefore, gives a comprehensive picture of trace metal-nanoparticle associations. While various studies have utilised FFF coupled to light scattering, [34][35][36][37][38][39][40][41][42][43][44][45] ICPMS, [7,[46][47][48][49][50][51][52] TEM [33,[53][54][55] or some combination thereof, many of these studies focussed on organic matter, synthetic nanoparticles, or uncontaminated river water. This study uses the above mentioned techniques to provide a first look at the direct associations between mineral nanoparticles and toxic trace metals in contaminated sediment.…”

Mass spectrometry for the characterization and quantification of engineered inorganic nanoparticles

“…So far, AF4 techniques have been used to characterize the synthesis and growth of different NPs (such as water-soluble Au and QDs) [43] and to detect TiO2-NPs in commercial products (e.g. sunscreen lotion) [44] using varied detectors.…”

Quantum dots and prion proteins

“…Besides these techniques, field flow fractionation, which belongs to high resolution liquid chromatography-like elution methods for separating and sizing, can be also successfully employed for QDs size distribution analysis. 85 The structure of QDs is usually analyzed by X-ray diffraction (XRD) 86 and the elemental composition of QDs can be studied by energy dispersive X-ray analysis (known as EDS, EDX, or EDAX). 82 Other techniques, like inductively coupled plasma atomic emission spectrometry (ICP-AES), were used for analysis of QDs as well, namely for the metal ions content in QDs.…”