Quantification of Quantum Dot Concentration Using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)

Sewell, Sarah L.; Higgins, M.; Bell, Charleson S; Giorgio, Todd D.

doi:10.1166/jbn.2011.1328

Cited by 10 publications

(7 citation statements)

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“…Because of the great diversity of NPs available and their associated physical and chemical properties, currently there is no single method broadly applicable to measure nanoparticle concentration. A few methods have been proposed to estimate the concentration of nanoparticles in solution based on microscopy measurements or by resorting to spectrophotometric determinations. , However, such methods suffer from a reduced accuracy and greatly depend on the matrix composition and the nanoparticle environment (e.g., nature of the surface coating). In fact, UV–vis spectroscopy has been proposed to estimate the concentration of other types of inorganic nanoparticles (e.g., gold nanoparticles or CdSe QDs).…”

Section: Resultsmentioning

confidence: 99%

Capping of Mn-Doped ZnS Quantum Dots with DHLA for Their Stabilization in Aqueous Media: Determination of the Nanoparticle Number Concentration and Surface Ligand Density

et al. 2017

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Colloidal Mn-doped ZnS quantum dots (QDs) were synthesized, surface modified, and thoroughly characterized using a pool of complementary techniques. Cap exchange of the native l-cysteine coating of the QDs with dihydrolipoic acid (DHLA) ligands is proposed as a strategy to produce nanocrystals with a strong phosphorescent-type emission and improved aqueous stability. Moreover, such a stable DHLA coating can facilitate further bioconjugation of these QDs to biomolecules using established reagents such as cross-linker molecules. First, a structural and morphological characterization of the l-cysteine QD core was performed by resorting to complementary techniques, including X-ray powder diffraction (XRD) and microscopy tools. XRD patterns provided information about the local structure of ions within the nanocrystal structure and the number of metal atoms constituting the core of a QD. The judicious combination of the data obtained from these complementary characterization tools with the analysis of the QDs using inductively coupled plasma-mass spectrometry (ICP-MS) allowed us to assess the number concentration of nanoparticles in an aqueous sample, a key parameter when such materials are going to be used in bioanalytical or toxicological studies. Asymmetric flow field-flow fractionation (AF4) coupled online to ICP-MS detection proved to be an invaluable tool to compute the number of DHLA molecules attached to the surface of a single QD, a key feature that is difficult to estimate in nanoparticles and that critically affects the behavior of nanoparticles when entering the biological media (e.g., cellular uptake, biodistribution, or protein corona formation). This hybrid technique also allowed us to demonstrate that the elemental composition of the nanoparticle core remains unaffected after the ligand exchange process. Finally, the photostability and robustness of the DHLA-capped QDs, critical parameters for bioanalytical applications, were assessed by molecular luminescence spectroscopy.

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Section: Resultsmentioning

confidence: 99%

Capping of Mn-Doped ZnS Quantum Dots with DHLA for Their Stabilization in Aqueous Media: Determination of the Nanoparticle Number Concentration and Surface Ligand Density

et al. 2017

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“…In these cases, a general strategy consists of the use of a SA-coated NP labeled with biotinylated secondary antibodies (b-Ab2) able to recognize the primary one (Ab1), which in turn targets specifically the protein under study. Such functionalization has been already reported for 4 QDs in some bioanalytical applications [15][16][17]. A rough estimation of the CdSe/ZnS QDs-SA stoichiometry using gel electrophoresis has been reported [18].…”

Section: Introductionmentioning

confidence: 88%

“…The absence of free b-Ab2 in the 216 resulting solution was further confirmed because any fluorescence peak was detected at its 217 original elution volume (14 mL, see Figure 1B). The significant decrease of the fluorescent 218 emission intensity observed in Figure 1B for the QDs-SA-b-Ab2 bioconjugate, in comparison to the injected original QDs-SA species, could be due to the fact that the biomolecules bound to the QD can alter its fluorescence properties [16]. Of course, elemental detection ( Figure 1A) does not suffer from this effect and that fact enabled us to derive some quantitative conclusions from the elemental profile (solid line, Figure 1A).…”

Section: Characterization Of Qds and Their Bioconjugatesmentioning

confidence: 96%

Sensitive targeted multiple protein quantification based on elemental detection of Quantum Dots

Bustos

Garcia-Cortes

González‐Iglesias

et al. 2015

Analytica Chimica Acta

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A generic strategy based on the use of CdSe/ZnS Quantum Dots (QDs) as elemental labels for protein quantification, using immunoassays with elemental mass spectrometry (ICP-MS), detection is presented. In this strategy, streptavidin modified QDs (QDs-SA) are bioconjugated to a biotinylated secondary antibody (b-Ab2). After a multi-technique characterization of the synthesized generic platform (QDs-SA-b-Ab2) it was applied to the sequential quantification of five proteins (transferrin, complement C3, apolipoprotein A1, transthyretin and apolipoprotein A4) at different concentration levels in human serum samples. It is shown how this generic strategy does only require the appropriate unlabeled primary antibody for each protein to be detected. Therefore, it introduces a way out to the need for the cumbersome and specific bioconjugation of the QDs to the corresponding specific recognition antibody for every target analyte (protein). Results obtained were validated with those obtained using UV-vis spectrophotometry and commercial ELISA Kits. As expected, ICP-MS offered one order of magnitude lower DL (0.23 fmol absolute for transferrin) than the classical spectrophotometric detection (3.2 fmol absolute). ICP-MS precision and detection limits, however turned out to be compromised by procedural blanks. The full analytical performance of the ICP-MS-based immunoassay proposed was assessed for detection of transferrin (Tf), present at the low ng mL(-1) range in a complex "model" synthetic matrix, where the total protein concentration was 100 μg mL(-1). Finally, ICP-MS detection allowed the quantitative control of all the steps of the proposed immunoassay, by computing mass balances obtained, and the development of a faster indirect immunoassay format where the plate wells were directly coated with the whole protein mixture sample.

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“…While the characterisation of synthesised QDs is widely covered in the literature, the research on the detection or quantification of QDs in complex samples is much more unusual. Thus, the detection/determination of QDs both directly (as inorganic or metal-free materials) [ 7 , 188 , 189 , 190 , 191 , 192 , 193 ] and indirectly (as the heavy metal content of inorganic materials) has been reported [ 11 , 12 , 54 , 56 , 194 , 195 , 196 , 197 , 198 , 199 , 200 , 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 , 209 , 210 ]. Nevertheless, for the indirect determination to be successful, the nature of the sample must be ensured; otherwise, the heavy metal content could come from sources other than the QDs themselves.…”

Section: Analytical Techniques For Detection and Quantification Of Qdsmentioning

confidence: 99%

Semiconductor Quantum Dots as Target Analytes: Properties, Surface Chemistry and Detection

et al. 2022

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Since the discovery of Quantum Dots (QDs) by Alexey I. Ekimov in 1981, the interest of researchers in that particular type of nanomaterials (NMs) with unique optical and electrical properties has been increasing year by year. Thus, since 2009, the number of scientific articles published on this topic has not been less than a thousand a year. The increasing use of QDs due to their biomedical, pharmaceutical, biological, photovoltaics or computing applications, as well as many other high-tech uses such as for displays and solid-state lighting (SSL), has given rise to a considerable number of studies about its potential toxicity. However, there are a really low number of reported studies on the detection and quantification of QDs, and these include ICP–MS and electrochemical analysis, which are the most common quantification techniques employed for this purpose. The knowledge of chemical phenomena occurring on the surface of QDs is crucial for understanding the interactions of QDs with species dissolved in the dispersion medium, while it paves the way for a widespread use of chemosensors to facilitate its detection. Keeping in mind both human health and environmental risks of QDs as well as the scarcity of analytical techniques and methodological approaches for their detection, the adaptation of existing techniques and methods used with other NMs appears necessary. In order to provide a multidisciplinary perspective on QD detection, this review focused on three interrelated key aspects of QDs: properties, surface chemistry and detection.

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Quantification of Quantum Dot Concentration Using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)

Cited by 10 publications

References 0 publications

Capping of Mn-Doped ZnS Quantum Dots with DHLA for Their Stabilization in Aqueous Media: Determination of the Nanoparticle Number Concentration and Surface Ligand Density

Capping of Mn-Doped ZnS Quantum Dots with DHLA for Their Stabilization in Aqueous Media: Determination of the Nanoparticle Number Concentration and Surface Ligand Density

Sensitive targeted multiple protein quantification based on elemental detection of Quantum Dots

Semiconductor Quantum Dots as Target Analytes: Properties, Surface Chemistry and Detection

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