Solid-state Nanoparticles Research Articles

Synthesis of protein-coated biocompatible methotrexate-loaded PLA-PEG-PLA nanoparticles for breast cancer treatment

BackgroundPLA-PEG-PLA triblock polymer nanoparticles are promising tools for targeted dug delivery. The main aim in designing polymeric nanoparticles for drug delivery is achieving a controlled and targeted release of a specific drug at the therapeutically optimal rate and choosing a suitable preparation method to encapsulate the drug efficiently, which depends mainly on the nature of the drug (hydrophilic or hydrophobic). In this study, methotrexate (MTX)-loaded nanoparticles were prepared by the double emulsion method.MethodBiodegradable polymer polyethylene glycol-polylactide acid tri-block was used with poly(vinyl alcohol) as emulsifier. The resulting methotrexate polymer nanoparticles were coated with bovine serum albumin in order to improve their biocompatibility. This study focused on particle size distribution, zeta potential, encapsulation efficiency, loading capacity, and in vitro drug release at various concentrations of PVA (0.5%, 1%, 2%, and 3%).ResultsReduced particle size of methotrexate-loaded nanoparticles was obtained using lower PVA concentrations. Enhanced encapsulation efficiency and loading capacity was obtained using 1% PVA. FT-IR characterization was conducted for the void polymer nanoparticles and for drug-loaded nanoparticles with methotrexate, and the protein-coated nanoparticles in solid state showed the structure of the plain PEG-PLA and the drug-loaded nanoparticles with methotrexate. The methotrexate-loaded PLA-PEG-PLA nanoparticles have been studied in vitro; the drug release, drug loading, and yield are reported.ConclusionThe drug release profile was monitored over a period of 168 hours, and was free of burst effect before the protein coating. The results obtained from this work are promising; this work can be taken further to develop MTX based therapies.

Visible-light-excited and europium-emissive nanoparticles for highly-luminescent bioimaging in vivo

Europium(III)-based material showing special milliseconds photoluminescence lifetime has been considered as an ideal time-gated luminescence probe for bioimaging, but is still limited in application in luminescent small-animal bioimaging in vivo. Here, a water-soluble, stable, highly-luminescent nanosystem, Ir–Eu–MSN (MSN = mesoporous silica nanoparticles, Ir–Eu = [Ir(dfppy)2(pic–OH)]3Eu·2H2O, dfppy = 2-(2,4-difluorophenyl)pyridine, pic–OH = 3-hydroxy-2-carboxypyridine), was developed by an in situ coordination reaction to form an insoluble dinuclear iridium(III) complex-sensitized-europium(III) emissive complex within mesoporous silica nanoparticles (MSNs) which had high loading efficiency. Compared with the usual approach of physical adsorption, this in-situ reaction strategy provided 20-fold the loading efficiency (43.2%) of the insoluble Ir–Eu complex in MSNs. These nanoparticles in solid state showed bright red luminescence with high quantum yield of 55.2%, and the excitation window extended up to 470 nm. These Ir–Eu–MSN nanoparticles were used for luminescence imaging in living cells under excitation at 458 nm with confocal microscopy, which was confirmed by flow cytometry. Furthermore, the Ir–Eu–MSN nanoparticles were successfully applied into high-contrast luminescent lymphatic imaging in vivo under low power density excitation of 5 mW cm−2. This synthetic method provides a universal strategy of combining hydrophobic complexes with hydrophilic MSNs for in vivo bioimaging.

Gas-phase synthesis of solid state DNA nanoparticles stabilized by l-leucine

Aerosol flow reactor is used to generate solid-state nanoparticles in a one-step process that is based on drying of aerosol droplets in continuous flow. We investigated the applicability of aerosol flow reactor method to prepare solid state DNA nanoparticles. Precursor solutions of plasmid DNA with or without complexing agent (polyethylenimine), coating material (l-leucine) and mannitol (bulking material) were dispersed to nanosized droplets and instantly dried in laminar heat flow. Particle morphology, integrity and stability were studied by scanning electron microscopy. The stability of DNA was studied by gel electrophoresis. Plasmid DNA as such degraded in the aerosol flow process. Complexing agent protected DNA from degradation and coating material enabled production of dispersed, non-aggregated, nanoparticles. The resulting nanoparticles were spherical and their mean diameter ranged from 65 to 125nm. The nanoparticles were structurally stable at room temperature and their DNA content was about 10%. We present herein the proof of principle for the production of dispersed solid state nanoparticles with relevant size and intact plasmid DNA.

Solid-state nanoparticle coated emulsions for encapsulation and improving the chemical stability of all-trans-retinol

Submicron oil-in-water (o/w) emulsions stabilised with conventional surfactants and silica nanoparticles were prepared and freeze-dried to obtain free-flowing powders with good redispersibility and a three-dimensional porous matrix structure. Solid-state emulsions were characterised for visual appearance, particle size distribution, zeta potential and reconstitution properties after freeze-drying with various sugars and at a range of sugar to oil ratios. Comparative degradation kinetics of all-trans-retinol from freeze-dried and liquid emulsions was investigated as a function of storage temperatures. Optimum stability was observed for silica-coated oleylamine emulsions at 4°C in their wet state. The half-life of all-trans-retinol was 25.66 and 22.08 weeks for silica incorporation from the oil and water phases respectively. This was ∼4 times higher compared to the equivalent solid-state emulsions with drug half-life of 6.18 and 6.06 weeks at 4°C. Exceptionally, at a storage temperature of 40°C, the chemical stability of the drug was 3 times higher in the solid-state compared to the wet emulsions which confirmed that freeze-drying is a promising approach to improve the chemical stability of water-labile compounds provided that the storage conditions are optimised.

A total-synthesis framework for the construction of high-order colloidal hybrid nanoparticles

Colloidal hybrid nanoparticles contain multiple nanoscale domains fused together by solid-state interfaces. They represent an emerging class of multifunctional lab-on-a-particle architectures that underpin future advances in solar energy conversion, fuel-cell catalysis, medical imaging and therapy, and electronics. The complexity of these 'artificial molecules' is limited ultimately by the lack of a mechanism-driven design framework. Here, we show that known chemical reactions can be applied in a predictable and stepwise manner to build complex hybrid nanoparticle architectures that include M-Pt-Fe(3)O(4) (M=Au, Ag, Ni, Pd) heterotrimers, M(x)S-Au-Pt-Fe(3)O(4) (M=Pb, Cu) heterotetramers and higher-order oligomers based on the heterotrimeric Au-Pt-Fe(3)O(4) building block. This synthetic framework conceptually mimics the total-synthesis approach used by chemists to construct complex organic molecules. The reaction toolkit applies solid-state nanoparticle analogues of chemoselective reactions, regiospecificity, coupling reactions and molecular substituent effects to the construction of exceptionally complex hybrid nanoparticle oligomers.

Nanocomposites based on globular photonic crystals grown by laser ablation using femtosecond laser pulses

The prepared samples were characterized by reflection and transmission spectra of broadband visible-range radiation, and the volume fraction of substances introduced into pores of artificial opals is estimated. It is found that the introduction of solid-state nanoparticles with negative real part of the permittivity into opal pores results in a decrease in the effective refractive index and a short-wavelength shift in the spectral position of the stop band in artificial opal.

Enhanced Spectral Sensing by Electromagnetic Coupling With Localized Surface Plasmons on Subwavelength Structures

Existing sensor platforms have limited sensitivity, specificity, and portability. With a new algorithm for the coupled dipole approximation of Maxwell's equations, we examine near- and far-field features of electromagnetism (EM) coupled with localized surface plasmons on subwavelength, solid-state nanoparticle (NP) structures measured using spectroscopy, microscopy, and calorimetry. <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Near-field</i> extinction efficiency, blue/redshifts, and full-width at half-maximum are optimized using a new ¿bottom-up¿ NP assembly method that tunes particle size and spacing to enhance sensitivity and produce molecule-specific ¿tenfold surface-enhanced Raman spectroscopy enhancements. <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Far-field</i> plasmon-photon resonances are identified, which offer ¿ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> -fold higher sensitivity. Solid-state NP structures increase stability, reduce power consumption, and improve response time and optothermal transduction up to tenfold for better portability and throughput relative to aggregation-prone NP suspensions. Sample rate is increased ¿tenfold by inducing transverse hydrodynamic diffusion adjacent to sensor interfaces. These results guide development of next-generation chemical and biological sensors based on EM-coupled UV, Raman, or terahertz modes that improve sensitivity, biospecificity, stability, and portability to distinguish biological molecules and species at high throughputs.

Synthesis of amphiphilic graft copolymer brush and its use as template film for the preparation of silver nanoparticles

AbstractA microphase‐separated, amphiphilic graft copolymer consisting of a poly (vinyl chloride) (PVC) backbone and poly(oxyethylene methacrylate) (POEM) side chains, (PVC‐g‐POEM at 62:38 wt %) was synthesized via atom transfer radical polymerization (ATRP). Nuclear magnetic resonance (1H NMR), FTIR spectroscopy, and transmission electron microscopy (TEM) clearly revealed that the “grafting from” method using ATRP was successful and that the graft copolymer molecularly self‐assembled into discrete nanophase domains of continuous PVC and isolated POEM regions. The self‐assembled graft copolymer film was used to template the growth of silver nanoparticles in solid state by introducing a AgCF3SO3 precursor and a UV irradiation process. The in situ formation of silver nanoparticles in the graft copolymer template film was confirmed by TEM, UV–visible spectroscopy, and wide angle X‐ray scattering. FTIR spectroscopy and X‐ray photoelectron spectroscopy also demonstrated the selective incorporation and in situ formation of silver nanoparticles within the hydrophilic POEM domains, presumably due to strong interactions between the silver and the ether oxygen in POEM. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3911–3918, 2008

Preparation and optical properties of organic nanoparticles of porphyrin without self-aggregation

We report the synthesis and optical properties of organic porphyrin nanoparticles with narrow size distribution and well dispersibility. Ion association between cationic meso-tetrakis(1-methylpyridinium-4-yl) porphine (TMPyP) and tetraphenylborate (TPB) anion or fluorinated derivatives of TPB, in the presence of polyvinylpyrrolidone (PVP), produces the porphyrin nanoparticles of ∼25 nm in aqueous solution. The TMPyP nanoparticles were stable in solution without precipitation for at least 30 days. No self-aggregation of the constituent porphyrin chromophores was confirmed. The TMPyP nanoparticles exhibited interesting optical properties; a large bathochromic shift in the absorption spectra and a resolution increase in the fluorescence spectra compared to those for the solution-phase TMPyP. A flattening of TMPyP molecules within the nanoparticles, which is caused by the twisting of four cationic methylpyridinium moieties, is the main origin for the large red shift. The resolution increase of fluorescence is due to the effect of immobilization of the methylpyridinium groups in the solid-state nanoparticles and/or that of a low polarity environment.

Effects of synthesis time for synthesizing single-walled carbon nanotubes over Mo–Fe–MgO catalyst and suggested growth mechanism

The influence of synthesis time on the synthesis of single-walled carbon nanotubes (SWCNTs) over Mo–Fe–MgO catalyst by decomposing CH 4 in Ar was studied by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. Very short and isolated SWCNTs with poor quality and high defect level were obtained and the carbon yield rate was low at 2 min. The SWCNTs were longer and the graphitization degree was higher as the synthesis time was increased. At 30 min, long bundles of SWCNTs with lower defect level were obtained, and most of the growth had taken place within 30 min. After this time, nearly no SWCNTs were generated without the presence of the active catalytic sites, but amorphous graphite was still deposited due to the continuous decomposition of CH 4. Carbon yield rate increased strongly with time up to 10 min. However, with longer growth time, the increase of carbon yield rate slowed, and the change of carbon yield rate was small after 30 min. The growth mechanism of SWCNTs over Mo–Fe–MgO catalyst was proposed according to the experimental results. The solid state nano-particles with high melting point on the surface of molten Fe–C droplets may be the active catalytic sites and play an important role in the formation of the SWCNT nucleus. The precipitation of carbon from the saturated Fe–C droplets leads to the formation of tubular carbon solids with an sp 2 structure.