Polymer-coated Nanoparticles Research Articles

Enhanced power generation using a novel polymer-coated nanoparticles dispersed-carbon micro-nanofibers-based air-cathode in a membrane-less single chamber microbial fuel cell

A novel polymer-metal nanoparticle-carbon micro-nanofiber-based nanocomposite was developed as an efficient air-cathode of a membrane-less single chamber microbial fuel cell (SMFC) for bio-energy production using Escherichia coli as a microbial catalyst. The polymeric material was synthesized using suspension polymerization, with polyvinyl alcohol as a monomer and poly methyl vinyl ether-alt-maleic anhydride (PMVEMA) as a cross-linking agent. The synthesized polymer composite was coated over the alumina (AA) and nickel (Ni) nanoparticles (NPs)-dispersed multi-scale web of activated carbon fiber (ACF) and carbon nanofiber (CNF). The PMVEMA polymer facilitated proton exchange from anolyte to cathode in SMFCs. AA:Ni-ACF/CNF served as an electron acceptor as well as the catalyst for atmospheric oxygen reduction at the cathode. The polarization curves determined using linear sweep voltammetry demonstrated the prepared polymer-metal-carbon nanocomposite to be an efficient air-cathode of the SMFC with a maximum electrical potential of 980 ± 10 mV and a maximum power density of 1270 ± 30 mW/m2.

Aggregation kinetics of stimulus-responsive polymer-coated gold nanoparticles driven by Hofmeister effects

Stability of engineered nanomaterials within natural aquatic systems is generally difficult to predict due to multiple roles that background electrolytes may play in these suspensions. Here we utilize core shell nanoparticles based on random copolymers of di(ethylene glycol) methyl ether methacrylate (x=MEO2MA) and oligo(ethylene glycol) methyl ether methacrylate (y=OEGMA) to investigate specific ion effects on colloidal stability. Aggregation kinetics (k11) of Au@(MEO2MAx-co-OEGMAy) NPs were measured for KCl, NaCl, SrCl2, and MgCl2 at various concentrations by means of time-resolved dynamic light scattering (TR-DLS). It was found that the smallest concentration of K+ and the greatest concentration of Mg2+ were required to increase the aggregation rate. Specifically, we demonstrate k11 scales not only as a result of ionic strength, but also in some cases in a direction opposite to that expected by the Schultz–Hardy rule. For these systems, aggregation kinetics can be better predicted by ion characterization within the well-established Hofmeister series.

Understanding the interactions between porphyrin-containing photosensitizers and polymer-coated nanoparticles in model biological environments

Non-covalent incorporation of hydrophobic drugs into polymeric systems is a commonly-used strategy for drug delivery because non-covalent interactions minimize modification of the drug molecules whose efficacy is retained upon release. The behaviors of the drug–polymer delivery system in the biological environments it encounters will affect the efficacy of treatment. In this report, we have investigated the interaction between a hydrophobic drug and its encapsulating polymer in model biological environments using a photosensitizer encapsulated in a polymer-coated nanoparticle system. The photosensitizer, 3-(1′-hexyloxyethyl)-3-devinylpyropheophorbide-a (HPPH), was non-covalently incorporated to the poly(ethylene glycol) (PEG) layer coated on Au nanocages (AuNCs) to yield AuNC–HPPH complexes. The non-covalent binding was characterized by Scatchard analysis, fluorescence lifetime, and Raman experiments. The dissociation constant between PEG and HPPH was found to be ∼35μM with a maximum loading of ∼2.5×105 HPPHs/AuNC. The release was studied in serum-mimetic environment and in vesicles that model human cell membranes. The rate of protein-mediated drug release decreased when using a negatively-charged or cross-linked terminus of the surface-modified PEG. Furthermore, the photothermal effect of AuNCs can initiate burst release, and thus allow control of the release kinetics, demonstrating on-demand drug release. This study provides insights regarding the actions and release kinetics of non-covalent drug delivery systems in biological environments.

A sensitive electrochemical sensor for rapid and selective determination of venlafaxine in biological fluids using carbon paste electrode modified with molecularly imprinted polymer-coated magnetite nanoparticles

Novel molecularly imprinted polymer-coated magnetite nanoparticles (VENMNPs) for the determination of venlafaxine (VEN) were introduced. The synthesized nanoparticles were used as a nano-modifier for carbon paste electrode. The modified electrode was used as an electrochemical sensor for electro-oxidation of venlafaxine, and subsequently for the drug sensitive and selective determination. Electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were employed to characterize the modified carbon paste electrode. Various experimental parameters, that can potentially affect the electrochemical signal of the electro-oxidation of VEN, including pH, VENMNPs dosage, stirring time, accumulation potential and time, were optimized. The results showed that under the optimum condition, sensitive determination of venlafaxine in concentration range 0.01–10.0 μmol L−1 is achievable. The detection limit for the drug determination was obtained as 6.0 nmol L−1. Finally, the results of the drug concentration analysis in human urine and blood serum samples showed that a powerful alternative method for VEN determination in biological fluids is developed.

Comparison of the in Vitro Uptake and Toxicity of Collagen- and Synthetic Polymer-Coated Gold Nanoparticles

We studied the physico-chemical properties (size, shape, zeta-potential), cellular internalization and toxicity of gold nanoparticles (NPs) stabilized with the most abundant mammalian protein, collagen. The properties of these gold NPs were compared to the same sized gold NPs coated with synthetic poly(isobutylene-alt-maleic anhydride) (PMA). Intracellular uptake and cytotoxicity were assessed in two cell lines (cervical carcinoma and lung adenocarcinoma cells) by employing inductively-coupled plasma-mass spectrometry (ICP-MS) analysis and a cell viability assay based on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), respectively. We found that the collagen-coated gold NPs exhibit lower cytotoxicity, but higher uptake levels than PMA-coated gold NPs. These results demonstrate that the surface coating of Au NPs plays a decisive role in their biocompatibility.

Conjugation of Polymer-Coated Gold Nanoparticles with Antibodies-Synthesis and Characterization.

The synthesis of polymer-coated gold nanoparticles with high colloidal stability is described, together with appropriate characterization techniques concerning the colloidal properties of the nanoparticles. Antibodies against vascular endothelial growth factor (VEGF) are conjugated to the surface of the nanoparticles. Antibody attachment is probed by different techniques, giving a guideline about the characterization of such conjugates. The effect of the nanoparticles on human adenocarcinoma alveolar basal epithelial cells (A549) and human umbilical vein endothelial cells (HUVECs) is probed in terms of internalization and viability assays.

Temperature-Triggered Protein Adsorption on Polymer-Coated Nanoparticles in Serum.

The protein corona, which forms on the nanoparticle's surface in most biological media, determines the nanoparticle's physicochemical characteristics. The formation of the protein corona has a significant impact on the biodistribution and clearance of nanoparticles in vivo. Therefore, the ability to influence the formation of the protein corona is essential to most biomedical applications, including drug delivery and imaging. In this study, we investigate the protein adsorption on nanoparticles with a hydrodynamic radius of 30 nm and a coating of thermoresponsive poly(2-isopropyl-2-oxazoline) in serum. Using multiangle dynamic light scattering (DLS) we demonstrate that heating of the nanoparticles above their phase separation temperature induces the formation of agglomerates, with a hydrodynamic radius of 1 μm. In serum, noticeably stronger agglomeration occurs at lower temperatures compared to serum-free conditions. Cryogenic transmission electron microscopy (cryo-TEM) revealed a high packing density of agglomerates when serum was not present. In contrast, in the presence of serum, agglomerated nanoparticles were loosely packed, indicating that proteins are intercalated between them. Moreover, an increase in protein content is observed upon heating, confirming that protein adsorption is induced by the alteration of the surface during phase separation. After cooling and switching the surface back, most of the agglomerates were dissolved and the main fraction returned to the original size of approximately 30 nm as shown by asymmetrical flow-field flow fractionation (AF-FFF) and DLS. Furthermore, the amounts of adsorbed proteins are similar before and after heating the nanoparticles to above their phase-separation temperature. Overall, our results demonstrate that the thermoresponsivity of the polymer coating enables turning the corona formation on nanoparticles on and off in situ. As the local heating of body areas can be easily done in vivo, the thermoresponsive coating could potentially be used to induce the agglomeration of nanoparticles and proteins and the accumulation of nanoparticles in a targeted body region.

Polymer-Coated Hollow Mesoporous Silica Nanoparticles for Triple-Responsive Drug Delivery.

In this study, pH, reduction and light triple-responsive nanocarriers based on hollow mesoporous silica nanoparticles (HMSNs) modified with poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) were developed via surface-initiated atom transfer radical polymerization. Both reduction-cleavable disulfide bond and light-cleavable o-nitrobenzyl ester were used as the linkages between HMSNs and pH-sensitive PDEAEMA polymer caps. A series of characterization techniques were applied to characterize and confirm the structures of the intermediates and final nanocarriers. Doxorubicin (DOX) was easily encapsulated into the nanocarriers with a high loading capacity, and quickly released in response to the stimuli of reducing agent, acid environment or UV light irradiation. In addition, flow cytometry analysis, confocal laser scanning microscopy observations and cytotoxicity studies indicated that the nanocarriers were efficiently internalized by HeLa cancer cells, exhibiting (i) enhanced release of DOX into the cytoplasm under external UV light irradiation, (ii) better cytotoxicity against HeLa cells, and (iii) superior control over drug delivery and release. Thus, the triple-responsive nanocarriers present highly promising potentials as a drug delivery platform for cancer therapy.

Abstract 3681: Facile fabrication of MRI-capable and NIR-resonant core-satellite nanomediators for photothermal therapy

Abstract Although many techniques exist for fabricating near-infrared (NIR)-resonant and magnetic resonance imaging (MRI)-capable nanomediators for photothermal cancer therapy, preparing them in an efficient and scalable process remains a significant challenge. In this report, we develop two facile methods to fabricate both NIR-resonant and MRI-capable nanomediators utilizing well developed polysiloxane-containing polymer-coated iron oxide nanoparticles (IONPs). One of the methods is to attach multiple NIR-resonant nanoparticles onto a thiol-modified IONP core through one-step mixing with gold sulfide nanoparticles (Au2S NPs) to fabricate a core-satellite nanomediator. The other strategy is to covalently attach a NIR organic dye onto intact polysiloxane-containing polymer-coated IONPs through facile mixing with siloxane-modified IR820. The successful decoration with either Au2S NPs or IR820 is demonstrated for the resultant nanomediators by absorption spectra and transmission electron microscopy (TEM) images. It is estimated that 10 Au2S NPs and 2×104 dye molecules (loading capacity: 4.5 mg IR820/mg Fe) are attached onto the polymer-coated IONPs, respectively. The hydrodynamic sizes of these novel multifunctional nanomediators are ∼57.5 nm for IONP-Au2S NP and 28.2 nm for IONP-IR820, which are much smaller than traditional gold nanoshell-based designs. The photothermal efficiency of the IONP-Au2S NP and IONP-IR820 nanocomposite solutions under the irradiation of 885 nm NIR laser light is significantly enhanced compared to IONPs alone. The enhancement in photothermal efficiency by the newly developed nanomediators is also investigated in nude mice bearing SUM-159 tumor xenografts. The biodistribution data measured by inductively coupled plasma optical emission spectrometry (ICP-OES) reveal that ∼1% injection dose (ID) of IONP-Au2S NPs and ∼9% ID of IONP-IR820 accumulate into tumor tissue 24 h post intravenous injection at a dose of 20 mg Fe/Kg mouse body weight. The average tumor surface temperature recorded by an infrared camera is increased by 10.8 ± 1.2 °C for the mice administered with IONP-Au2S NPs and 25.7 ± 3.6 °C for the group injected with IONP-IR820, compared to 4.8 ± 0.5 °C for the PBS-injected control mice after laser irradiation with a power of 0.5 W for 10 min. Furthermore, our data reveal that the fabrication will not compromise the IONP core capability as an MRI contrast agent. Taken together, we demonstrate a facile technique to generate NIR-resonant and MRI-capable nanomediators from a polysiloxane-containing polymer-coated IONP platform. The as-developed dual functional nanomediators hold great promise for translatable MRI-guided photothermal cancer therapy. Citation Format: Hongwei Chen, Xiaoqing Ren, Hayley Paholak, Joseph Burnett, Feng Ni, Duxin Sun. Facile fabrication of MRI-capable and NIR-resonant core-satellite nanomediators for photothermal therapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3681. doi:10.1158/1538-7445.AM2015-3681

Toxicity mechanisms of ionic silver and polymer-coated silver nanoparticles with interactions of functionalized carbon nanotubes on early development stages of sea urchin

Exposures of aquatic organisms to multiple contaminants are likely to take place in estuarine and coastal areas and combined effects on early life stages have to be examined. Among emerging contaminants, ionic silver (Ag+) and silver nanoparticles (AgNps) have demonstrated contrasting effects on marine invertebrates, but their interactions with functionalized carbon nanotubes (f-SWCNTs) have not yet been investigated in details. In order to observe the impacts and understand the toxicity mechanism of Ag+ and polymer-coated AgNps, and their combined effects with f-SWCNTs, successive development stages of embryos of sea urchin, Strongylocentrotus droebachiensis, were exposed to Ag+, AgNps and f-SWCNTs, separately and in mixtures using moderate environmental concentrations. We also assessed long-term effects of treatments under recovery conditions. Morphological endpoints such as archenteron elongation, primary and secondary mesenchyme cells fate, pigment cells migration, spiculogenic cells and gut development indicated different effects of silver and nanosilver forms during successive development stages. Whereas Ag+ induced vegetalization and extrusion of mesenchyme cells on early embryos; f-SWCNTs+Ag+ strongly interfered with gut regionalization in late larvae. Sensitive blastocoelar cells got vacuolized and shapeless with AgNps, but not with mixtures with f-SWCNTs. Increased concentrations of Ag+ and f-SWCNTs+Ag+ led to the most disruptive effects during development, but f-SWCNTs+Ag+ caused the highest mortality rate during the recovery period, which indicated far-reaching effects driven by f-SWCNTs and their ability to keep silver more available during exposure period.

Studies on polymer-coated zinc oxide nanoparticles: UV-blocking efficacy and in vivo toxicity.

Zinc oxide (ZnO) is explicitly used in sunscreens and cosmetic products; however, its effect in vivo is toxic in some cases. The UV blocking efficacy of ZnO nanoparticles is lost due to photocatalysis. To isolate a lower toxic species of sunblockers, ZnO nanoparticles were synthesized and coated with chitosan - a natural polymer (ZnO-CTS) and polyethylene glycol (PEG) - a synthetic polymer (ZnO-PEG). Coating with CTS and PEG circumvented the photocatalytic activity, increased the stability and improved the UV absorption efficacy. The effect of ZnO, ZnO-CTS and ZnO-PEG nanoparticles in vivo on zebrafish embryo revealed lower deposition of ZnO-CTS and ZnO-PEG nanoparticles atop the eggs compared to ZnO. The survival of zebrafish embryos was always found to be higher in case of ZnO-CTS with respect to ZnO-treated ones. PEG coating exhibited better UV attenuation, but, in vivo it induced delayed hatching. Thus, one of the reasons for better survival could be attributed to lower aggregation of ZnO-CTS nanoparticles atop eggs thereby facilitating the breathing of embryos.

Aggregation of superparamagnetic iron oxide nanoparticles in dilute aqueous dispersions: Effect of coating by double-hydrophilic block polyelectrolyte

Abstract Polymer-coated superparamagnetic iron oxide nanoparticles (SPION) in aqueous dispersion were prepared by the coassembly of SPION coated by an oleate bilayer with the double hydrophilic block polyelectrolyte poly[(3,5-bis(trimethylammoniummethyl)-4-hydroxystyrene iodide]- block -poly(ethylene oxide) (QNPHOS-PEO) and characterized by TEM and AFM. It was found that the coating by QNPHOS-PEO affects their aggregation into larger structures on the micrometer length scale observed by small-angle light scattering as well as the dynamics of the dispersion observed by dynamic light scattering. Oleate-SPION in aqueous dispersions form compact aggregates with the fractal dimension, D = 2.4, and the characteristic size about 2 μm which exhibit internal dynamics manifesting itself by the presence of the relaxation mode with τ ∼ q −3 . In the case of QNPHOS-PEO/oleate-SPION dispersions, the polyelectrolyte coating promotes the formation of compact clusters with the size of the order of ∼10 2 nm. The clusters, weakly interacting by magnetic dipolar interactions, form linear chainlike aggregates with the low fractal dimension, D = 1.2. The dynamics of the QNPHOS-PEO/oleate-SPION dispersions observed by DLS is dominated by the diffusion of the clusters.

Surface Functionalization of Nanoparticles with Polyethylene Glycol: Effects on Protein Adsorption and Cellular Uptake.

Here we have investigated the effect of enshrouding polymer-coated nanoparticles (NPs) with polyethylene glycol (PEG) on the adsorption of proteins and uptake by cultured cells. PEG was covalently linked to the polymer surface to the maximal grafting density achievable under our experimental conditions. Changes in the effective hydrodynamic radius of the NPs upon adsorption of human serum albumin (HSA) and fibrinogen (FIB) were measured in situ using fluorescence correlation spectroscopy. For NPs without a PEG shell, a thickness increase of around 3 nm, corresponding to HSA monolayer adsorption, was measured at high HSA concentration. Only 50% of this value was found for NPs with PEGylated surfaces. While the size increase clearly reveals formation of a protein corona also for PEGylated NPs, fluorescence lifetime measurements and quenching experiments suggest that the adsorbed HSA molecules are buried within the PEG shell. For FIB adsorption onto PEGylated NPs, even less change in NP diameter was observed. In vitro uptake of the NPs by 3T3 fibroblasts was reduced to around 10% upon PEGylation with PEG chains of 10 kDa. Thus, even though the PEG coatings did not completely prevent protein adsorption, the PEGylated NPs still displayed a pronounced reduction of cellular uptake with respect to bare NPs, which is to be expected if the adsorbed proteins are not exposed on the NP surface.

In vivo integrity of polymer-coated gold nanoparticles.

Inorganic nanoparticles are frequently engineered with an organic surface coating to improve their physicochemical properties, and it is well known that their colloidal properties may change upon internalization by cells. While the stability of such nanoparticles is typically assayed in simple in vitro tests, their stability in a mammalian organism remains unknown. Here, we show that firmly grafted polymer shells around gold nanoparticles may degrade when injected into rats. We synthesized monodisperse radioactively labelled gold nanoparticles ((198)Au) and engineered an (111)In-labelled polymer shell around them. Upon intravenous injection into rats, quantitative biodistribution analyses performed independently for (198)Au and (111)In showed partial removal of the polymer shell in vivo. While (198)Au accumulates mostly in the liver, part of the (111)In shows a non-particulate biodistribution similar to intravenous injection of chelated (111)In. Further in vitro studies suggest that degradation of the polymer shell is caused by proteolytic enzymes in the liver. Our results show that even nanoparticles with high colloidal stability can change their physicochemical properties in vivo.

Facile Fabrication of Near-Infrared-Resonant and Magnetic Resonance Imaging-Capable Nanomediators for Photothermal Therapy.

Although many techniques exist for fabricating near-infrared (NIR)-resonant and magnetic resonance imaging (MRI)-capable nanomediators for photothermal cancer therapy, preparing them in an efficient and scalable process remains a significant challenge. In this report, we exploit one-step siloxane chemistry to facilely conjugate NIR-absorbing satellites onto a well-developed polysiloxane-containing polymer-coated iron oxide nanoparticle (IONP) core to generate dual functional core-satellite nanomediators for photothermal therapy. An advantage of this nanocomposite design is the variety of potential satellites that can be simply attached to impart NIR resonance, which we demonstrate using NIR-resonant gold sulfide nanoparticles (Au2SNPs) and the NIR dye IR820 as two example satellites. The core-satellite nanomediators are fully characterized by using absorption spectra, dynamic light scattering, ζ potential measurements, and transmission electron microscopy. The enhanced photothermal effect under the irradiation of NIR laser light is identified through in vitro solutions and in vivo mice studies. The MRI capabilities as contrast agents are demonstrated in mice. Our data suggest that polysiloxane-containing polymer-coated IONPs can be used as a versatile platform to build such dual functional nanomediators for translatable, MRI-guided photothermal cancer therapy.

A new approach to reduce toxicities and to improve bioavailabilities of platinum-containing anti-cancer nanodrugs.

Platinum (Pt) drugs are the most potent and commonly used anti-cancer chemotherapeutics. Nanoformulation of Pt drugs has the potential to improve the delivery to tumors and reduce toxic side effects. A major challenge for translating nanodrugs to clinical settings is their rapid clearance by the reticuloendothelial system (RES), hence increasing toxicities on off-target organs and reducing efficacy. We are reporting that an FDA approved parenteral nutrition source, Intralipid 20%, can help this problem. A dichloro (1, 2-diaminocyclohexane) platinum (II)-loaded and hyaluronic acid polymer-coated nanoparticle (DACHPt/HANP) is used in this study. A single dose of Intralipid (2 g/kg, clinical dosage) is administrated [intravenously (i. v.), clinical route] one hour before i.v. injection of DACHPt/HANP. This treatment can significantly reduce the toxicities of DACHPt/HANP in liver, spleen, and, interestingly, kidney. Intralipid can decrease Pt accumulation in the liver, spleen, and kidney by 20.4%, 42.5%, and 31.2% at 24-hr post nanodrug administration, respectively. The bioavailability of DACHPt/HANP increases by 18.7% and 9.4% during the first 5 and 24 hr, respectively.

High-performance polyvinylidene fluoride/poly(styrene–butadiene–styrene)/functionalized MWCNTs-SCN-Ag nanocomposite membranes

In this work, solution blending technique was used to fabricate nano-filtration membranes of polyvinylidene fluoride (PVDF) and poly(styrene–butadiene–styrene) (SBS) blend matrix and modified multi-walled carbon nanotubes (MWCNTs) as filler. In this regard, two types of nanofiller, thiocyanate-modified nanotubes (MWCNTs-SCN) and silver-modified nanotubes (MWCNTs-SCN-Ag), were used as reinforced nanofiller in PVDF/SBS blend to form PVDF/SBS-MWCNTs-SCN 0.01–0.1 and PVDF/SBS-MWCNTs-SCN-Ag 0.01–0.1 membranes. Fourier transform infrared; field emission scanning electron microscopy; transmission electron microscopy; X-ray photoelectron spectroscopy; Brunauer, Emmett and Teller; and tensile tests were used for the exploration of structural and physical properties. Morphology studies showed the dispersion of polymer-coated silver nanoparticles with smooth and homogeneous surface in the spongy matrix. Porous nature of membranes was also observed in high-resolution cross-section micrographs. Tensile strength of PVDF/SBS-MWCNTs-SCN 0.01–1 nanocomposite series increased from 10.2 to 13.9 MPa, while PVDF/SBS-MWCNTs-SCN-Ag 0.01–1 had values in the range of 12.6–20.1 MPa. According to TGA, PVDF/SBS-MWCNTs-SCN revealed maximum decomposition temperature around 550–580 °C, while PVDF/SBS-MWCNTs-SCN-Ag had T max of 567–599 °C. The influence of various filler content on membrane performance and structure was studied using pertinent methods and techniques. Percentage of water content of PVDF/SBS-MWCNTs-SCN 0.01–0.1 was estimated around 1.08–2.80 % and this value was further increased to 1.94–4.65 % in silver nanoparticle-modified system. Moreover, the porosity of silver nanoparticle-modified system was found superior compared with the other composites. Pure water flux, salt rejection, and recovery were also found optimal for 0.05 wt% silver nanoparticle-based modified system. According to the consequences, novel membranes have fine nano-filtration characteristics to be utilized in advance water treatment industrial units.

Organic matter induced mobilization of polymer-coated silver nanoparticles from water-saturated sand

Mobilization of polymer-coated silver nanoparticles (AgNPs) by anionic surfactant (sodium dodecylbenzenesulphonate: SDBS), amino acid derivative (N-acetylcysteine: NAC), and chelate (ethylenediaminetetraacetic acid: EDTA) in water-saturated sand medium was explored based on carefully designed column tests. Exposure experiments monitoring the size evolution of polyvinylpyrrolidone (PVP) coated AgNPs in organic solutions confirm the capacity of SDBS, NAC and EDTA to partly displace PVP. Single Pulse Column Experiment (SPCE) results show both the PVP polymer and the silver core controlled AgNP deposition while the effect of the PVP was dominant. Results of Co-injected Pulse Column Experiments (CPCEs) where AgNP and SDBS or NAC were co-injected into the column following a very short mixing (<1s) disprove our hypothesis that coating-alternation by particle associated organic would mobilize irreversibly deposited particles from the uncoated sand, while surface charge modification by adsorbed NAC was identified as a potential mobilizing mechanism for AgNP from the iron-oxide-coated sand. Triple Pulse Column Experiment (TPCE) results confirm that such a charging effect of the adsorbed organic molecules may enable SDBS and NAC to mobilize AgNPs from the iron-oxide-coated sands. TPCE results with five distinct levels of SDBS indicate that concentration-stimulated change in the SDBS format from an individual to a micelle significantly increased the mobilizing efficiency and site blockage of SDBS. Although being an electrolyte, EDTA did not mobilize AgNPs, as the case with SDBS or NAC, as it dissolved the iron oxides which in turn prevented EDTA adsorption on sand. The findings have implications for better understanding the behavior of polymer-coated nanoparticles in organic-presented groundwater systems, i.e., detachment-associated uncertainty in exposure prediction of the nanomaterials.

A fluorimetric study on the interaction between a Trp-containing beta-strand peptide and amphiphilic polymer-coated gold nanoparticles.

Owing to the inevitability of nanoparticles encountering proteins/peptides in current bio-nano-medicine development, it is important to know how they interact with each other in vitro before developing in vivo applications. To this end, a model de novo β-sheet-forming peptide and typical biocompatible nanoparticles were selected to study thermodynamic aspects of their interactions via a fluorescence quenching method. The results showed that Pep11 and AuNPs spontaneously formed conjugates, mainly driven by a coulombic interaction with a binding affinity of ~ 0.1 µM(-1); the physical adsorption process was cooperative. These results deepen our quantitative understanding of nanoparticle-peptide interactions. The results may also be helpful in further nanoparticle-peptide hybrid nanofabrication and also useful for the application of nanoparticles in the treatment of amyloid diseases.

Study on iron oxide nanoparticles coated with glucose-derived polymers for biomedical applications

This study reports an approach for a facile one-step synthesis of magnetic nanoparticles (MNPs) coated with glucose-derived polymers (GDP) through a mechanochemical hydrothermal process for biomedical applications. Polymer-coated magnetic nanoparticles (Fe2O3/Fe3O4), with sizes below 10nm, exhibited superparamagnetic behavior, with a specific magnetization saturation value of about 40emu/g, and a maximum specific absorption rate (SAR) of 30W/g in AC magnetic fields. Depending on the intensity of the applied AC magnetic field, a temperature of 42°C can be achieved in 4–17min. The surface polymerized layer affords functional hydroxyl groups for binding to biomolecules containing carboxyl, thiol, or amino groups, thereby making the coated nanoparticles feasible for bio-conjugation. In vitro cytotoxicity evaluation pointed out that a relatively high concentration of polymer-coated magnetic nanoparticles (GDP-MNPs) did not induce severe cell alteration, suggesting a good biocompatibility.