Nanoparticles In Water Research Articles

Nanoparticle tracking analysis versus dynamic light scattering: Case study on the effect of Ca2+ and alginate on the aggregation of cerium oxide nanoparticles.

The effect of Ca2+ and alginate on the stability of CeO2 nanoparticles (NPs) was investigated using dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA); the two methods were then compared. DLS showed rapid aggregation of CeO2 NPs in 8 mM Ca2+ solution; however, NTA showed that some primary aggregates (200-400 nm) still remained-a result that was obscured in DLS measurements. Aggregation of alginate molecules was also studied using DLS and NTA, where NTA particle concentration and video provided additional information on the alginate aggregation progress. Finally, DLS showed that in the presence of alginate, the aggregation rate and size of CeO2 NPs increased. NTA intensity measurements provided insight into a heteroaggregation and bridging mechanism. NTA particle concentration and video also showed CeO2 NPs were linked by alginate gel in high Ca2+ concentration (>4 mM). the DLS and NTA had different advantages in measuring particle size. DLS could better study the initial aggregation stage and large aggregates, while NTA could better detect small aggregates. NTA also measured particle number concentration, individual intensity, and particle motion video, which provided additional insight. Combining these two methods could help us to better understand the behavior and fate of NPs in water.

Cobalt ferrite nanoparticles supported on electrospun carbon fiber as a magnetic heterogeneous catalyst for activating peroxymonosulfate

Cobalt ferrite (CF) nanoparticle (NP) represents a promising alternative to Co3O4 NP for peroxymonosulfate (PMS) activation in view of its strong magnetism for easy recovery. As CF NPs in water are prone to agglomerate, a few attempts have been made to immobilize CF NPs on substrates. While carbonaceous supports are more favorable owing to their earth abundancy, the study of carbon-supported CF for PMS activation is limited to graphene-based CF, which, however, requires complicated protocols to prepare. As carbon-supported CF, by straightforward preparation, is still greatly desired, this study aims to employ electrospinning techniques for preparing carbon-supported CF by carbonizing an electrospun CF-embedded polyacrylonitrile (PAN) fiber. After carbonization, the CF-PAN fiber is converted into CF-embedded carbon nanofiber (CF@CNF), which contains well distributed CF NPs, high magnetism and stable carbon support, making CF@CNF a highly promising catalyst for activating PMS. As amaranth decolorization is used as a model reaction, CF@CNF is able to activate PMS for generating sulfate radicals and then decolorize amaranth in water. Amaranth decolorization by CF@CNF-PMS is also substantially facilitated at elevated temperature, and enhanced under the weakly acidic condition. CF@CNF also remains effective to activate PMS even in the presence of salts and surfactants, and re-usable over multiple cycles. Compared to other reported catalysts, CF@CNF also exhibited a much lower Ea value (35.8 kJ/mol) for amaranth decolorization. These features validate that CF@CNF is an advantageous and convenient catalyst for activating PMS.

Micellization of a di‐block copolymer in ethylene glycol and its utilization for suspension of carbonaceous nanostructures

ABSTRACTSuspensions of carbonaceous nanoparticles (NPs) in ethylene glycol (EG) can be used as colloidal inks for additive manufacturing and nano‐fluids for heat‐transfer applications. While micellar solutions of surfactants are often used for suspension of the NPs in water, micellization of surfactants in EG is suppressed as compared to aqueous solutions and a well‐defined critical micellization concentration (CMC) is often not observed. Unlike the surfactants, a di‐block copolymer comprising a poly(ethylene glycol) monomethylether methacrylate (PEGMA) segment, 2‐(diethylaminoethyl) methacrylate (DEAEMA) and butyl methacrylate (BMA), poly(O950)‐b‐(DEAEMA‐co‐BMA) was found to assemble into spherical micelles in EG. Surface tension measurements show a well‐defined CMC that depends on the volume fraction of EG. Cryogenic transmission electron microscopy and dynamic light scattering show the presence of spherical micelles with a diameter that reduces with the volume fraction of EG. The micellar solutions were further used for suspending carbonaceous NPs of different geometry and characteristic dimensions: C60 fullerenes, multi‐walled carbon nanotubes, and nanodiamonds. The flow behavior of the suspensions exhibits a relatively low viscosity and mostly Newtonian behavior due to strong interaction between the NPs and the micelles. These suspensions may be used as colloidal inks for two‐dimensional and three‐dimensional printing. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46518.

Development of redox-responsive theranostic nanoparticles for near-infrared fluorescence imaging-guided photodynamic/chemotherapy of tumor

The development of imaging-guided smart drug delivery systems for combinational photodynamic/chemotherapy of the tumor has become highly demanded in oncology. Herein, redox-responsive theranostic polymeric nanoparticles (NPs) were fabricated innovatively using low molecular weight heparin (LWMH) as the backbone. Chlorin e6 (Ce6) and alpha-tocopherol succinate (TOS) were conjugated to LMWH via cystamine as the redox-sensitive linker, forming amphiphilic Ce6-LMWH-TOS (CHT) polymer, which could self-assemble into NPs in water and encapsulate paclitaxel (PTX) inside the inner core (PTX/CHT NPs). The enhanced near-infrared (NIR) fluorescence intensity and reactive oxygen species (ROS) generation of Ce6 were observed in a reductive environment, suggesting the cystamine-switched “ON/OFF” of Ce6. Also, the in vitro release of PTX exhibited a redox-triggered profile. MCF-7 cells showed a dramatically higher uptake of Ce6 delivered by CHT NPs compared with free Ce6. The improved therapeutic effect of PTX/CHT NPs compared with mono-photodynamic or mono-chemotherapy was observed in vitro via MTT and apoptosis assays. Also, the PTX/CHT NPs exhibited a significantly better in anti-tumor efficiency upon NIR irradiation according to the results of in vivo combination therapy conducted on 4T1-tumor-bearing mice. The in vivo NIR fluorescence capacity of CHT NPs was also evaluated in tumor-bearing nude mice, implying that the CHT NPs could enhance the accumulation and retention of Ce6 in tumor foci compared with free Ce6. Interestingly, the anti-metastasis activity of CHT NPs was observed against MCF-7 cells by a wound healing assay, which was comparable to LMWH, suggesting LMWH was promising for construction of nanocarriers for cancer management.

Synthesis and Characterization of Core–Shell and Multi–Shell Plasmonic Nanoparticles for Molecular Sensing and Photothermal Applications

Event Abstract Back to Event Synthesis and Characterization of Core–Shell and Multi–Shell Plasmonic Nanoparticles for Molecular Sensing and Photothermal Applications Asela S. Dikkumbura1, Holden T. Smith1, Rami A. Khoury1, Jeewan C. Ranasinghe1 and Louis H. Haber1* 1 Louisiana State University, United States The synthesis, characterization, photothermal measurements, molecular adsorption properties, and spectral resonant coupling of colloidal silver–gold core–shell (Ag@Au CS) and gold–silver–gold core–shell–shell (Au@Ag@Au CSS) nanoparticles (NPs) are reported. These NPs have potential applications in photothermal cancer therapies, drug delivery, and molecular sensing. Transmission electron microscopy images show that these NPs are spherical in shape with controllable core and shell dimensions. Temperature measurements using 800 nm laser irradiation show that the colloidal 76 nm Ag@Au CS and 109 nm Au@Ag@Au CSS NPs have higher photothermal efficiencies compared to corresponding spherical gold and silver NPs. Second harmonic generation (SHG) spectroscopy is used to investigate the adsorption properties of malachite green and brilliant green to the surface of 76 nm Ag@Au CS NPs which are capped with mercaptosuccinic acid in water. The experimental adsorption isotherms obtained from SHG measurements are fit using the modified Langmuir model to obtain the free energies of adsorption and the adsorbate site densities. Difference extinction spectroscopy measurements show plasmonic and molecular resonance coupling caused by the formation of new polaritonic states and Fano–type resonances with corresponding plasmon and molecular spectral depletions as the adsorbate concentration is increased. The dependence of the molecular resonance coupling under varying plasmonic spectra will provide important insight into polaritonic spectroscopy for developing improved molecular sensing and plasmon enhancement applications. Additionally, the synthesis and characterization of silver–silica core–shell (Ag@SiO2 CS) NPs are also discussed for future SHG χ^((3) ) measurements on size-dependent ion adsorption and surface charge density experiments on colloidal Ag@SiO2 CS NPs in water. The combined approach of synthesis and characterization of different CS NPs with SHG spectroscopy provides for detailed studies of molecular and optical interactions with hybrid plasmonic colloidal samples for developing enhanced nanomaterial technologies. Keywords: Silver, Gold, Nanoparticles, core-shell, Core-shell-shell, Photothermal, Second haramonic generation, Adsorption isotherms, resonance coupling Conference: National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE) 45th Annual Conference , Orlando, Florida, United States, 17 Sep - 20 Sep, 2018. Presentation Type: Poster Presentation Topic: Nanochemistry Citation: Dikkumbura AS, Smith HT, Khoury RA, Ranasinghe JC and Haber LH (2019). Synthesis and Characterization of Core–Shell and Multi–Shell Plasmonic Nanoparticles for Molecular Sensing and Photothermal Applications. Front. Chem. Conference Abstract: National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE) 45th Annual Conference . doi: 10.3389/conf.fchem.2018.01.00027 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 08 Oct 2018; Published Online: 17 Jan 2019. * Correspondence: Dr. Louis H Haber, Louisiana State University, Baton Rouge, United States, lhaber@lsu.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Asela S Dikkumbura Holden T Smith Rami A Khoury Jeewan C Ranasinghe Louis H Haber Google Asela S Dikkumbura Holden T Smith Rami A Khoury Jeewan C Ranasinghe Louis H Haber Google Scholar Asela S Dikkumbura Holden T Smith Rami A Khoury Jeewan C Ranasinghe Louis H Haber PubMed Asela S Dikkumbura Holden T Smith Rami A Khoury Jeewan C Ranasinghe Louis H Haber Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The presence of palmitate affected the colloidal stability of ZnO NPs but not the toxicity to Caco-2 cells

Nanoparticles (NPs) are finding increasing use in food science, but the toxicity of NPs following oral exposure is not fully known. When present in food and food-related products, food components may interact with NPs and thus influence the toxicity of NPs, but relatively few studies have considered the interactions between food components and ZnO NPs. In this study, the interactions between ZnO NPs with different sizes (20 and 100 nm; uncoated) and palmitate (PA) on the toxicity of NPs to Caco-2 cells were investigated. The presence of PA altered UV-Vis spectra, hydrodynamic size, and zeta potential of ZnO NPs of both sizes, which indicated an interaction between PA and ZnO NPs. Furthermore, the interaction decreased the solubility of ZnO NPs in water and cell culture medium. Exposure to both types of ZnO NPs was associated with significantly increased cytotoxicity, lysosomal damages, and intracellular Zn accumulation but not reactive oxygen species (ROS) or release of interleukin-8 (IL-8) in Caco-2 cells. The presence of 100 μM PA did not significantly affect all of these endpoints, and ANOVA analysis indicated no interaction between concentrations of ZnO NPs and the presence of PA. It is concluded that PA as a saturated fatty acid may influence the colloidal stability of ZnO NPs but did not affect the toxicity of ZnO NPs to Caco-2 cells.

Retraction of "Transient Photothermal Spectra of Plasmonic Nanobubbles".

The photothermal efficacy of near-infrared gold nanoparticles (NP), nanoshells, and nanorods was studied under pulsed high-energy optical excitation in plasmonic nanobubble (PNB) mode as a function of the wavelength and duration of the excitation laser pulse. PNBs, transient vapor nanobubbles, were generated around individual and clustered overheated NPs in water and living cells. Transient PNBs showed two photothermal features not previously observed for NPs: the narrowing of the spectral peaks to 1 nm and the strong dependence of the photothermal efficacy upon the duration of the laser pulse. Narrow red-shifted (relative to those of NPs) near-infrared spectral peaks were observed for 70 ps excitation laser pulses, while longer sub- and nanosecond pulses completely suppressed near-infrared peaks and blue shifted the PNB generation to the visual range. Thus, PNBs can provide superior spectral selectivity over gold NPs under specific optical excitation conditions.

Effect of pH values on recovery of nano particles (NPs) from the fine fraction of automobile shredder residue (ASR): An application of NPs for phenol removal from the water

Nano particles (NPs) were synthesized from leachate of fine fraction (<0.25mm) of automobile shredder residue (ASR) at pH levels of 3, 5, 7, 9 and 12. The removal of phenol using NPs in water was investigated to determine whether applying NPs for phenol removal from wastewater would be feasible. The recovered NPs were analyzed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). In this research, phenol degradation was studied with hydrogen peroxide to assess the potential applicability of NPs for the treatment of wastewater. The results of the SEM and TEM analyses show that the separated NPs were <50nm in size. The FTIR spectra indicate the presence of CO and OH bonds in the NPs. The XRD results show the presence of metals oxides of Fe, Zn, and Cu, among others, on the surfaces of the NPs. The results of the XPS analyses show that various elements (e.g., C, O, Zn, and Fe) existed in the recovered NPs. The degree of phenol degradation by NPs in the presence of hydrogen peroxide was significant. Phenol degradation was found to be 100% for NPs synthesized at pH levels of 3 and 7 at a reaction time of 210min. A pseudo-first-order kinetic model showed a very good fit to the phenol degradation results. The probable mechanism for the removal of phenol by NPs was the degradation of phenol by hydroxyl radicals which were produced during the reaction between H2O2 and NPs in a liquid medium. The results of the present study indicate that NPs recovered from low-grade ASR can be applied for the removal of phenolic compounds from water.

Synthesis and characterization of gold/water nanofluids suitable for thermal applications produced by femtosecond laser radiation

A laser-based “green” synthesis of nanoparticles (NPs) was used to manufacture gold NPs in water. The light source is a Ti:Sapphire laser with 30 fs FWHM pulses, 800 nm mean wavelength, and 1 kHz repetition rate. The method involves two stages: (1) pulsed laser ablation in liquids and (2) photo-fragmentation (PF). Highly pure and well-dispersed NPs with a diameter of 18.5 nm that can be stored at room temperature without showing any agglomeration over a period of at least 3 months were produced without the need to use any stabilizer. Transmittance spectra, extinction coefficient, NPs agglomeration dynamics, and thermal conductivity of the nanofluids obtained were analyzed before and after being submitted to thermal cycling and compared to those obtained for commercial gold/water suspensions. Optical properties have also been investigated, showing no substantial differences for thermal applications between NPs produced by the laser ablation and PF technique and commercial NPs. Therefore, nanofluids produced by this technique can be used in thermal applications, which are foreseen for conventional nanofluids, e.g., heat transfer enhancement and solar radiation direct absorption, but offering the opportunity to produce them in situ in almost any kind of fluid without the production of any chemical waste.

Functional double-shelled silicon nanocrystals for two-photon fluorescence cell imaging: spectral evolution and tuning.

Functional near-IR (NIR) emitting nanoparticles (NPs) adapted for two-photon excitation fluorescence cell imaging were obtained starting from octadecyl-terminated silicon nanocrystals (ncSi-OD) of narrow photoluminescence (PL) spectra having no long emission tails, continuously tunable over the 700-1000 nm window, PL quantum yields exceeding 30%, and PL lifetimes of 300 μs or longer. These NPs, consisting of a Pluronic F127 shell and a core made up of assembled ncSi-OD kept apart by an octadecyl (OD) layer, were readily internalized into the cytosol, but not the nucleus, of NIH3T3 cells and were non-toxic. Asymmetrical field-flow fractionation (AF4) analysis was carried out to determine the size of the NPs in water. HiLyte Fluor 750 amine was linked via an amide link to NPs prepared with Pluronic-F127-COOH, as a first demonstration of functional NIR-emitting water dispersible ncSi-based nanoparticles.

Studies on linear, nonlinear optical and excited state dynamics of silicon nanoparticles prepared by picosecond laser ablation

We report results from our studies on the fabrication and characterization of silicon (Si) nanoparticles (NPs) and nanostructures (NSs) achieved through the ablation of Si target in four different liquids using ∼2 picosecond (ps) pulses. The consequence of using different liquid media on the ablation of Si target was investigated by studying the surface morphology along with material composition of Si based NPs. The recorded mean sizes of these NPs were ∼9.5 nm, ∼37 nm, ∼45 nm and ∼42 nm obtained in acetone, water, dichloromethane (DCM) and chloroform, respectively. The generated NPs were characterized by selected area electron diffraction (SAED), high resolution transmission microscopy (HRTEM), Raman spectroscopic techniques and Photoluminescence (PL) studies. SAED, HRTEM and Raman spectroscopy data confirmed that the material composition was Si NPs in acetone, Si/SiO2 NPs in water, Si-C NPs in DCM and Si-C NPs in chloroform and all of them were confirmed to be polycrystalline in nature. Surface morphological information of the fabricated Si substrates was obtained using the field emission scanning electron microscopic (FESEM) technique. FESEM data revealed the formation of laser induced periodic surface structures (LIPSS) for the case of ablation in acetone and water while random NSs were observed for the case of ablation in DCM and chloroform. Femtosecond (fs) nonlinear optical properties and excited state dynamics of these colloidal Si NPs were investigated using the Z-scan and pump-probe techniques with ∼150 fs (100 MHz) and ∼70 fs (1 kHz) laser pulses, respectively. The fs pump-probe data obtained at 600 nm consisted of single and double exponential decays which were tentatively assigned to electron-electron collisional relaxation (&amp;lt;1 ps) and non-radiative transitions (&amp;gt;1 ps). Large third order optical nonlinearities (∼10−14 e.s.u.) for these colloids have been estimated from Z-scan data at an excitation wavelength of 680 nm suggesting that the colloidal Si NPs find potential applications in photonic devices.

Temperature-dependent breakdown of hydrogen peroxide-treated ZnO and TiO2 nanoparticle agglomerates.

Metal oxide nanoparticles (MONPs) are used in a variety of applications including drug formulations, paint, sensors and biomedical devices due to their unique physicochemical properties. One of the major problems with their widespread implementation is their uncontrolled agglomeration. One approach to reduce agglomeration is to alter their surface chemistry with a proper functionality in an environmentally friendly way. In this study, the influence of hydrogen peroxide (H2O2) treatment on the dispersion of ZnO and TiO2 nanoparticle (NP) agglomerates as a function of temperature is studied. The H2O2 treatment of the MONPs increases the density of hydroxyl (–OH) groups on the NP surface, as verified with FTIR spectroscopy. The influence of heating on the dispersion of H2O2-treated ZnO and TiO2 NPs is investigated using dynamic light scattering. The untreated and H2O2-treated ZnO and TiO2 NP suspensions were heated from 30 °C to 90 °C at 5 °C intervals to monitor the breakdown of large aggregates into smaller aggregates and individual nanoparticles. It was shown that the combined effect of hydroxylation and heating enhances the dispersion of ZnO and TiO2 NPs in water.

SU-E-T-518: Investigation of Gold Nanoparticle Radiosensitization for Carbon Ion Therapy

Purpose The aim of this work is to investigate the radiosensitization effect of gold nanoparticles (GNP) in carbon ion irradiation. Nano-scale dosimetric characteristics of GNP interaction with carbon ions as well as the secondary particles generated as a carbon beam traverses the water phantom were studied. Methods Monte Carlo simulations were carried out using TOPAS (Tool for Particle Simulation). First, a water phantom was irradiated by the carbon ion beam and the particle shower spectrum at several depths was recorded in phase spaces. We analyzed the number and energy spectrum of each particle type. Then, the phase spaces obtained from Step 1 were modified to nanometer scale to irradiate a single 50 nm GNP. The secondary electrons that escaped from the GNPs following interactions with each particle type were recorded as phase spaces. The number and energy spectrum of the secondary electrons were studied. The same simulations were repeated replacing the GNPs with water nanoparticles (WNPs) with the same size. The energy absorbed in either GNP or WNP was scored. Results There is a large amount of secondary particles generated through carbon ion beam interaction with the water phantom. Analysis of the secondary electrons generated by the primary particles which escape from the nanoparticle revealed that majority (above 80%) of these electrons were generated by the GNP interaction with Carbon beam itself, making it the biggest contributor to the enhancement. The ratio of the energy absorbed by GNP and WNP is about 8–10 for charged particles and above 3000 for gammas. Conclusion We showed in the study the GNPs may potentially be used to enhance carbon ion therapy, and the main mechanism of enhancement is the interaction with Carbon ion particles itself.

Red-emitting DPSB-based conjugated polymer nanoparticles with high two-photon brightness for cell membrane imaging.

New red-emitting conjugated polymers have been successfully synthesized by incorporating classical two-photon absorption (TPA) units, electron-rich units, and a small amount of electron-deficient units along the polymer backbones. Water-dispersible nanoparticles (NPs) based on these polymers were also fabricated for applications in two-photon excitation fluorescence imaging of cell membrane. Through optimization of the polymer/matrix mass ratio and the initial feed concentration of the polymer solution, a high quantum yield (QY) of 24% was achieved for the red-emitting NPs in water. TPA cross section and two-photon action cross section values of these polymers at 750 nm reached up to 1000 GM and 190 GM per repeat unit in aqueous media, 2.5 × 10(5) GM and 4.7 × 10(4) GM per NP, respectively. Furthermore, these NPs displayed excellent photostability and biocompatibility. Their applications as two-photon excitation fluorescence probes for cell membrane imaging have been demonstrated in three different cell lines with excellent imaging contrast. These results demonstrated that these polymer NPs hold great potentials as excellent two-photon excitation fluorescence probes in various biological applications.

Dispersion Stability, Ligand Structure and Conformation, and SERS Activities of 1-Alkanethiol Functionalized Gold and Silver Nanoparticles

Dispersion stability, ligand structure and conformation, and SERS activities of 1-alkanethiol (CnH2n+1SH, n = 2–14) functionalized gold and silver nanoparticles (AuNPs and AgNPs) were studied as a function of alkanethiol carbon chain length and nanoparticle (NP) type and size. The dispersion stability of alkanethiol functionalized NPs in water increases with increasing alkanethiol chain length and NP size, and the stabilities of the alkanethiol-containing AuNPs are higher than their AgNP counterparts. C3H7SH and longer alkanethiols are highly ordered on AgNPs but disordered on AuNPs. The SERS intensity of the C–S stretch band for the model alkanethiols on AgNPs and AuNPs decays exponentially (I = I0 exp(−Nc/N0)) with increasing number of carbon atoms (Nc). The empirical decay length N0, in terms of the number of the carbon atoms, is 1.29, 0.53, and 0.10 for AgNPs with diameters of 50, 30, and 10 nm, respectively. This decay length is less than 1 for AuNPs of difference sizes. These results show that changing the NP gap size by a distance equivalent to a single chemical bond can have a significant impact on the NP integrated SERS activities.

Differential stress reaction of human colon cells to oleic-acid-stabilized and unstabilized ultrasmall iron oxide nanoparticles.

Therapeutic engineered nanoparticles (NPs), including ultrasmall superparamagnetic iron oxide (USPIO) NPs, may accumulate in the lower digestive tract following ingestion or injection. In order to evaluate the reaction of human colon cells to USPIO NPs, the effects of non-stabilized USPIO NPs (NS-USPIO NPs), oleic-acid-stabilized USPIO NPs (OA-USPIO NPs), and free oleic acid (OA) were compared in human HT29 and CaCo2 colon epithelial cancer cells. First the biophysical characteristics of NS-USPIO NPs and OA-USPIO NPs in water, in cell culture medium supplemented with fetal calf serum, and in cell culture medium preconditioned by HT29 and CaCo2 cells were determined. Then, stress responses of the cells were evaluated following exposure to NS-USPIO NPs, OA-USPIO NPs, and free OA. No modification of the cytoskeletal actin network was observed. Cell response to stress, including markers of apoptosis and DNA repair, oxidative stress and degradative/autophagic stress, induction of heat shock protein, or lipid metabolism was determined in cells exposed to the two NPs. Induction of an autophagic response was observed in the two cell lines for both NPs but not free OA, while the other stress responses were cell- and NP-specific. The formation of lipid vacuoles/droplets was demonstrated in HT29 and CaCo2 cells exposed to OA-USPIO NPs but not to NS-USPIO NPs, and to a much lower level in cells exposed to equimolar concentrations of free OA. Therefore, the induction of lipid vacuoles in colon cells exposed to OA utilized as a stabilizer for USPIO NPs is higly amplified compared to free OA, and is not observed in the absence of this lipid in NS-USPIO NPs.

Preparation and investigation of high solid content PTX-loaded nanoparticles dispersion via nanoprecipitation method

The improvement of the solid content of the hydrophobic drugs (such as paclitaxel (PTX), etc.) loaded nanoparticles (NPs) dispersion is important for enhancing drug-loaded efficiency and reducing the cost in production and application. A diblock copolymer methoxy poly(ethylene glycol)-b-poly(ε-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone) (mPECT) is synthesized via the ring-opening polymerization of ε-caprolactone and 1,4,8-trioxa[4.6]spiro-9-undecanone (TOSUO) with methoxy poly(ethyleneglycol) (mPEG） as the initiator. The chemical structures and thermal properties of mPECT are characterized by 1HNMR, Fourier transform infrared (FT-IR), gel permeation chromatography, differential scanning calorimetry, etc. PEG45.45-b-P(C28.33-co-T5.38) (mPECT-2) is able to self-assemble into stable NPs in water via nanoprecipitation method at a high solid content (≤25 wt%) and their freeze-dried powders can well re-disperse in water. The paclitaxel (PTX) is chosen as a hydrophobic drug model and successfully encapsulate into the mPECT-2 NPs via the same method at a high solid content. The encapsulation efficiency, cytotoxicity and in vitro release of PTX-loaded NPs are investigated. The results suggest that the behavior of the drug-loaded mPECT-2 NPs prepared at a solid content of 25 wt% is similar to that of NPs prepared at a solid content of 1 wt%, which indicate that increasing solid content of polymer has no negative effect on the properties of NPs dispersion in application. In summary, the freeze-dried NPs prepared from the high solid content dispersion (≤25 wt%) has a good redispersibility and exhibits great potential in cost control of preparing NPs dispersion used as drug delivery system.

Characterization of Biodegradable Polyurethane Nanoparticles and Thermally Induced Self-Assembly in Water Dispersion

Waterborne polyurethanes (PU) with different compositions of biodegradable oligodiols as the soft segment were synthesized as nanoparticles (NPs) in this study. Using dynamic light scattering (DLS), multiangle light scattering (MALS), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS), we demonstrated that these NPs were compact spheres with different shape factors. The temperature-dependent swelling of the PU NPs in water was distinct. In particular, PU NPs with 80 mol % polycaprolactone (PCL) diol and 20 mol % poly(L-lactide) (PLLA) diol as the soft segment had significant swelling (∼450%) at 37 °C. This was accompanied by a sol-gel transition observed in about 2 min for the NP dispersion. The thermally induced swelling and self-assembly of these NPs were associated with the secondary force (mainly hydrogen bonding) and degree of crystallinity, which depended on the soft segment compositions. The thermo-responsiveness of the PU NPs with mixed biodegradable oligodiols may be employed to design smart biodegradable carriers for delivery of cells or drugs near body temperature.

A novel method for the synthesis of Fe3O4 nanoparticles/CdS nanowires heterostructure nanocomposite and uses in photodegradation of methylene blue

We report here a simple, efficient, practical, and novel method for the preparation of Fe3O4 nanoparticles (NPs)/CdS nanowires. The CdS nanowire/Fe3O4 NP reported here was characterized by transmission electron microscopy (TEM), X-ray Diffraction (XRD), vibrating sample magnetometer (VSM), and energy-dispersive X-ray. Cadmium diethyl dithiophosphate has been used as a 3 in 1 precursor (cadmium, sulfur, and ligand source) for the synthesis of high-quality one-dimensional Fe3O4 NPs/CdS nanowires using a simple hydrothermal method in the presence of Fe3O4 NPs in water. Photocatalytic activity studies show that the nanocomposite has good photocatalytic activity toward the photodegradation of methylene blue in an aqueous solution.

Hyperspectral imaging (HSI) to evaluate the interaction of optically active nanoparticles in biological media and cells

Hyperspectral Imaging (HSI) is a technique that can be used with darkfield microscopy for investigating biological interactions of optically active nanoparticles (NP) based on their spectral signatures. The objective of this study is to investigate the capabilities of HSI technology to characterize (1) spectral characteristics of gold, silver, and manganese NPs, (2) stability of gold NPs in exposure media and growth media based on spectral shifts, and (3) cellular interaction of NPs by correlating spectral data between NPs in water or media and NPs exposed to cells. Results demonstrate the unique spectral characteristics of the NPs investigated. Gold and silver NPs both display plasmonic properties; however, gold NPs exhibited a more narrow spectral profile. Silver NPs demonstrated several distinct scattering spectra due to the strong dependence on morphology. Manganese NPs do not display plasmonic properties, but still exhibited a unique spectral response, allowing them to be detected in cells. Due to the narrow spectral profile for gold NPs, stability was investigated in biological media, demonstrating the ability for HSI to detect the stabilizing effect of serum on NPs. Cellular interaction studies showed that the peak scattering wavelength for NPs in cells deviated from NPs in water or media, but NPs were still able to be identified based on intensity and shape of the scattering curves. Overall, HSI was demonstrated as a useful technique for evaluating optically active NPs in biological media and cellular environments.