Adaptive Interactions between Zinc Oxide Nanoparticles and <i>Chlorella</i> sp.

The effects of ZnO nanoparticles (NPs) interacting with single-celled green algae, <i>Chlorella</i> sp., have been found to be bilateral. Specifically, our electron microscopy, plant cell, and fluorescence assays showed that the adsorption and aggregation of ZnO NPs compromised algal cell morphology, viability, and membrane integrity, resulting from zinc ion dissolution as well as possible mechanical cell damage induced by the NPs. Conversely, algal cells displayed a remarkable capability of self-protection by minimizing their surface area through aggregation mediated by the oppositely charged metal ions and suppressing zinc ion release from the NPs through exudation, as evidenced by inductively coupled plasma mass spectrometry, zeta potential, and attenuated total reflectance-Fourier transform infrared spectroscopy. This study illustrates the adaptive nature and complexity in potential ecological response to discharged nanomaterials

PAMAM Dendrimers and Graphene: Materials for Removing Aromatic Contaminants from Water

We present results from experiments and atomistic molecular dynamics simulations on the remediation of naphthalene by polyamidoamine (PAMAM) dendrimers and graphene oxide (GrO). Specifically, we investigate 3^rd–6^th generation (G3-G6) PAMAM dendrimers and GrO with different levels of oxidation. The work is motivated by the potential applications of these emerging nanomaterials in removing polycyclic aromatic hydrocarbon contaminants from water. Our experimental results indicate that GrO outperforms dendrimers in removing naphthalene from water. Molecular dynamics simulations suggest that the prominent factors driving naphthalene association to these seemingly disparate materials are similar. Interestingly, we find that cooperative interactions between the naphthalene molecules play a significant role in enhancing their association to the dendrimers and GrO. Our findings highlight that while selection of appropriate materials is important, the interactions between the contaminants themselves can also be important in governing the effectiveness of a given material. The combined use of experiments and molecular dynamics simulations allows us to comment on the possible factors resulting in better performance of GrO in removing polyaromatic contaminants from water

Silver Nanoparticle Protein Corona Composition in Cell Culture Media

<div><p>The potential applications of nanomaterials as drug delivery systems and in other products continue to expand. Upon introduction into physiological environments and driven by energetics, nanomaterials readily associate proteins forming a protein corona (PC) on their surface. This PC influences the nanomaterial’s surface characteristics and may impact their interaction with cells. To determine the biological impact of nanomaterial exposure as well as nanotherapeutic applications, it is necessary to understand PC formation. Utilizing a label-free mass spectrometry-based proteomics approach, we examined the composition of the PC for a set of four silver nanoparticles (AgNPs) including citrate-stabilized and polyvinlypyrrolidone-stabilized (PVP) colloidal silver (20 or 110 nm diameter). To simulate cell culture conditions, AgNPs were incubated for 1 h in Dulbecco’s Modified Eagle Medium supplemented with 10% fetal bovine serum, washed, coronal proteins solubilized, and proteins identified and quantified by label-free LC-MS/MS. To determine which attributes influence PC formation, the AgNPs were characterized in both water and cell culture media with 10% FBS. All AgNPs associated a common subset of 11 proteins including albumin, apolipoproteins, keratins, and other serum proteins. 110 nm citrate- and PVP-stabilized AgNPs were found to bind the greatest number of proteins (79 and 85 respectively) compared to 20 nm citrate- and PVP-stabilized AgNPs (45 and 48 respectively), suggesting a difference in PC formation based on surface curvature. While no relationships were found for other protein parameters (isoelectric point or aliphatic index), the PC on 20 nm AgNPs (PVP and citrate) consisted of more hydrophobic proteins compared to 110 nm AgNPs implying that this class of proteins are more receptive to curvature-induced folding and crowding in exchange for an increased hydration in the aqueous environment. These observations demonstrate the significance of electrostatic and hydrophobic interactions in the formation of the PC which may have broad biological and toxicological implications.</p></div

AgNP suspension characterization in water or serum-free cell culture media.

<p>AgNP suspension characterization in water or serum-free cell culture media.</p

The individual abundance of each of the 11 common proteins found to associate with all AgNPs.

<p>The individual abundance of each of the 11 common proteins found to associate with all AgNPs.</p

Scanning electron microscopy images and size distribution of A) 20 nm citrate-stabilized AgNP, B) 20 nm PVP-stabilized AgNP, C) 110 nm citrate-stabilized AgNP, and D) 110 nm PVP-stabilized AgNP samples confirming the diameters of all AgNPs used in this study.

<p>Scanning electron microscopy images and size distribution of A) 20 nm citrate-stabilized AgNP, B) 20 nm PVP-stabilized AgNP, C) 110 nm citrate-stabilized AgNP, and D) 110 nm PVP-stabilized AgNP samples confirming the diameters of all AgNPs used in this study.</p

Total number of constituent and unique proteins found to associate with AgNPs after incubation in DMEM cell culture media containing 10% fetal bovine serum (2A).

<p>Samples were analyzed via HPLC-MS and proteins and peptides were identified using the UniProtKB Bos Taurus (Bovine) database and validated by PeptideProphet. Only proteins with a probability ≥0.9, or peptides with a probability ≥0.8, and a peptide weight ≥0.5 were used in the quantitation algorithm. Correlation of total number of constituent proteins found to associate with each AgNP and zeta potential (2B) or hydrodynamic diameter (2C).</p

20 most abundant coronal proteins associated with each AgNP.

<p>Italized proteins are unique to that AgNP corona; <b>Bold</b> proteins are common to all AgNP coronas (from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0074001#pone-0074001-g003" target="_blank">Figure 3</a>).</p

The number of unique proteins detected in each AgNP protein corona after incubation in DMEM cell culture media containing 10% fetal bovine serum (3A).

<p>Samples were analyzed via HPLC-MS and proteins and peptides were identified using the UniProtKB Bos Taurus (Bovine) database and validated by PeptideProphet. Only proteins with a probability ≥0.9, or peptides with a probability ≥0.8, and a peptide weight ≥0.5 were used in the quantitation algorithm. Correlation of the number of unique proteins found to associate with each AgNP and zeta potential (3B) or hydrodynamic diameter (3C).</p

Dendrimer–Fullerenol Soft-Condensed Nanoassembly

Nanoscale assembly is an area of research that has vast implications for molecular design, sensing, nanofabrication, supramolecular chemistry, catalysis, and environmental remediation. Here we show that poly­(amidoamine) (PAMAM) dendrimers of both generations 1 (G1) and 4 (G4) can host 1 fullerenol per 2 dendrimer primary amines as evidenced by isothermal titration calorimetry, dynamic light scattering, and spectrofluorometry. Thermodynamically, the interactions were similarly spontaneous between both generations of dendrimers and fullerenols, however, G4 formed stronger complexes with fullerenols resulting from their higher surface charge density and more internal voids, as demonstrated by spectrofluorometry. In addition to hydrogen bonding that existed between the dendrimer primary amines and the fullerenol oxygens, hydrophobic and electrostatic interactions also contributed to complex formation and dynamics. Such a hybrid of soft and condensed nanoassembly may have implications for environmental remediation of discharged nanomaterials and entail new applications in drug delivery