Direct experimental observation of the aggregation of α-amino acids into 100–200 nm clusters in aqueous solution

Hagmeyer, Daniel; Ruesing, Johannes; Fenske, Tassilo; Klein, Heinz‐Werner; Schmuck, Carsten; Schräder, Wolfgang; Piedade, Manuel E. Minas da; Epple, Matthias

doi:10.1039/c2ra01352e

Cited by 52 publications

(52 citation statements)

References 15 publications

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“…Indeed, the dynamics of organic clusters might generally be slower than those of inorganic compounds, and a qualitative assessment of cluster dynamics by means of AUC cannot provide unambiguous evidence about whether or not the detected clusters are actually phase separated. Also, the much larger amino acid associates reported by Hagmeyer et al 40. and Jawor-Baczynska et al 41.…”

Section: Resultsmentioning

confidence: 91%

Growth of organic crystals via attachment and transformation of nanoscopic precursors

et al. 2017

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A key requirement for the understanding of crystal growth is to detect how new layers form and grow at the nanoscale. Multistage crystallization pathways involving liquid-like, amorphous or metastable crystalline precursors have been predicted by theoretical work and have been observed experimentally. Nevertheless, there is no clear evidence that any of these precursors can also be relevant for the growth of crystals of organic compounds. Herein, we present a new growth mode for crystals of DL-glutamic acid monohydrate that proceeds through the attachment of preformed nanoscopic species from solution, their subsequent decrease in height at the surface and final transformation into crystalline 2D nuclei that eventually build new molecular layers by further monomer incorporation. This alternative mechanism provides a direct proof for the existence of multistage pathways in the crystallization of molecular compounds and the relevance of precursor units larger than the monomeric constituents in the actual stage of growth.

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Section: Resultsmentioning

confidence: 91%

Growth of organic crystals via attachment and transformation of nanoscopic precursors

et al. 2017

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“…Even though we do realize the limitation of such an approach, we believe that it would allow, at least, a direct comparison of our data with other literature on light scattering of solutions of low-molecular-weight compounds. [12,42,43] Typical correlation functions and intensity-weighted size distributions for solutions of d-levoglucosan in water are shown in Table 1S. The DLS data for all concentrations are summarized in Table 3, and the analysis of concentration dependence of size distributions revealed areas of concentration in which similar types of light-scattering "particles" exist.…”

Section: Light Scattering Experimentsmentioning

confidence: 99%

Polarimetry as a Tool for the Study of Solutions of Chiral Solutes

et al. 2013

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Optical rotation of aqueous solutions of D-levoglucosan was studied experimentally in the 0.03-4.0 mol L(-1) concentration range and a nonlinear concentration dependence of specific optical rotation (SR) was revealed. Discontinuities observed in the concentration plot of SR (at 0.1, 0.3, 0.5, 1.0, and 2.0 mol L(-1)) are well correlated with those found by static and dynamic light scattering and identify concentration ranges in which different solution domains (supramers) may exist. The average SR experimental value for a D-levoglucosan aqueous solution ([α]D(28) -58.5±8.7 deg dm(-1) cm(-3) g(-1)) was found to be in good agreement with values obtained by theoretical calculation (TD-DFT/GIAO) of SR for 15 different conformers revealed by conformational sampling at the PCM/B3LYP/6-311++G(2d,2p)//B3LYP/6-31+G(d,p) level, which were shown to be strongly affected by the solvation microenvironment (0, 1, 2, and 3 explicit solvent molecules considered) due to local geometrical changes induced in the solute molecule. This exceptionally high sensitivity of SR makes polarimetry a unique method capable of sensing changes in the structure of supramers detected in this study.

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“…It has been shown that intermolecular interaction such as hydrogen bondings between aminoacid molecules can cause formation of aggregates with about 100 to 200 nanometer sizes in water. 34 The aminoacid molecules attached on to the different ZnS:Mn nanocrystals can also attract to each other by hydrogen bonding interaction between aminoacid-aminoacid or aminoacid-water(solvent)-aminoacid moieties. However, since alanine molecules contain an additional free-rotating methyl group from glycine, they can also cause larger van der Waals repulsion between the capping molecules on the different nanocrystals during the aggregation process.…”

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confidence: 99%

Biological Toxicities and Aggregation Effects of ʟ-Glycine and ʟ-Alanine Capped ZnS:Mn Nanocrystals in Aqueous Solution

Park¹,

Song²,

Kong³

et al. 2014

Bulletin of the Korean Chemical Society

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In this study, water-dispersible ZnS:Mn nanocrystals were synthesized by capping the surface with conventional and simple structured amino acid ligands: L-Glycine and L-Alanine. The ZnS:Mn-Gly and ZnS:Mn-Ala nanocrystal powders were characterized by XRD, HR-TEM, EDXS, ICP-AES, and FT-IR spectroscopy. The optical properties were measured by UV-Visible and photoluminescence (PL) spectroscopy. The PL spectra for the ZnS:Mn-Gly and ZnS:Mn-Ala showed broad emission peaks at 599 nm and 607 nm with PL efficiencies of 6.5% and 7.8%, respectively. The measured average particle size from the HR-TEM images were 6.4 ± 0.8 nm (ZnS:Mn-Gly) and 4.1 ± 0.5 nm (ZnS:Mn-Ala), which were also supported by Debye-Scherrer calculations. In addition, the degree of aggregation of the nanocrystals in aqueous solutions were measured by a hydrodynamic light scattering method, which showed formation of sub-micrometer size aggregates for both ZnS:Mn-Gly (273 ± 94 nm) and ZnS:Mn-Ala (233 ± 34 nm) in water due to the intermolecular attraction between the capping amino acids molecules. Finally, the cytotoxic effects of ZnS:Mn-Gly and ZnS:Mn-Ala nanocrsystals over the growth of wild type E. coli were investigated. As a result, no toxicity was shown for the ZnS:Mn-Gly nanocrystal in the colloidal concentration region from 1 µg/mL to 1000 µg/mL, while ZnS:MnAla showed significant toxicity at 100 µg/mL.

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Direct experimental observation of the aggregation of α-amino acids into 100–200 nm clusters in aqueous solution

Cited by 52 publications

References 15 publications

Growth of organic crystals via attachment and transformation of nanoscopic precursors

Growth of organic crystals via attachment and transformation of nanoscopic precursors

Polarimetry as a Tool for the Study of Solutions of Chiral Solutes

Biological Toxicities and Aggregation Effects of ʟ-Glycine and ʟ-Alanine Capped ZnS:Mn Nanocrystals in Aqueous Solution

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