In vitro effects of cisplatin-functionalized silica nanoparticles on chondrocytes

In this study, we evaluated the combined effect of a known toxic molecule, cisplatin, in combination with relatively nontoxic nanoparticles, amorphous fumed silica, on chondrocyte cells. Cisplatin was attached to silica nanoparticles using aminopropyltriethoxy silane as a linker molecule, and characterized in terms of size, shape, specific surface area, as well as the dissolution of cisplatin from the silica surface. The primary particle diameter of the as-received silica nanoparticles ranged from 7.1 to 61 nm, estimated from measurements of specific surface area, and the primary particles were aggregated. The effects of cisplatin-functionalized silica particles with different specific surface areas (41, 85, 202, 237, and 297 m²/g) were compared in vitro on chondrocytes, the parenchymal cell of hyaline cartilage. The results show that adverse effects on cell function, as evidenced by reduced metabolic activity measured by the MTT assay and increased membrane permeability observed using the Live/Dead stain, can be correlated with specific surface area of the silica. Cisplatin-functionalized silica nanoparticles with the highest specific surface area incited the greatest response, which was almost equivalent to that induced by free cisplatin. This result suggests the importance of particle specific surface area in interactions between cells and surface-functionalized nanomaterials.     

Synthesis and characterization of microporous hollow core-shell silica nanoparticles (HCSNs) of tunable thickness for controlled release of doxorubicin

Hollow core-shell silica nanoparticles (HCSNs) are being considered as one of the most favorable drug carriers to accomplish targeted drug delivery. In the present study, we developed a simple two-step method, employing polystyrene (PS) nanoparticles (150?±?20 nm) as a sacrificial template for the synthesis of microporous HCSNs of size 230?±?30 nm. PS core and the wall structure directing agent cetyl trimethyl ammonium bromide (CTAB) were removed by calcination. Monodispersed spherical HCSNs were synthesized by optimising the parameters like water/ethanol volume ratio, PS/tetraethyl orthosilicate (TEOS) weight ratio, concentration of ammonia, and CTAB. Transmission electron microscopy (TEM) revealed the formation of hollow core-shell structure of silica with tunable thickness from 15 to 30 nm while tailoring the concentration of silica precursor. The results obtained from the cumulative release studies of doxorubicin loaded microporous HCSNs demonstrated the dependence of shell thickness on the controlled drug release behavior. HCSNs with highest shell thickness of 30 nm and lowest surface area of 600 m²/g showed delay in the doxorubicin release, proving their application as a drug carrier in targeted drug delivery systems. The novel concept of application of microporous HCSNs of pore size ~?1.3 nm with large specific surface area in the field of drug delivery is successful.     

Comparison of Eu(NO<Subscript>3</Subscript>)<Subscript>3</Subscript> and Eu(acac)<Subscript>3</Subscript> precursors for doping luminescent silica nanoparticles

In this study, we report the comparison between Eu³⁺-doped silica nanoparticles synthesized by Stöber method using Eu(NO₃)₃ or Eu(acac)₃ as precursors. The impact of different europium species on the properties of the final silica nanospheres is investigated in details in terms of size, morphology, reachable doping amount, and luminescence efficiency. Moreover, the results obtained for different thermal treatments are presented and discussed. It is shown that the organic complex modify the silica growing process, leading to bigger and irregular nanoparticles (500–800 nm) with respect to the perfectly spherical ones (400 nm) obtained by the nitrate salt, but their luminescence intensity and lifetime is significantly higher when 800–900 °C annealing is performed.     

Silver nanoparticles produced by PLD in vacuum: role of the laser wavelength used

In this work we report the results of investigation of silver (Ag) nanoparticles prepared on a silica substrate by laser ablation. Our attention was focused on the mean diameter, size distribution and optical absorption properties of nanoparticles prepared in vacuum by using different laser wavelengths. The fundamental wavelength and the second, third, and fourth harmonics of a nanosecond Nd:YAG laser were used for nanoparticles fabrication. The corresponding values of the laser fluence for each wavelength were: 0.6 J/cm² at 266 nm, 0.8 J/cm² at 355 nm, 2.8 J/cm² at 532 nm, and 2 J/cm² at 1064 nm. The Ag nanoparticles produced have mean diameters in the range from 2 nm to 12 nm as the nanoparticles’ size decreases with the decrease of the wavelength used. The presence of the Ag nanoparticles was also evidenced by the appearance of a strong optical absorption band in the measured UV-VIS spectra associated with surface plasmon resonance (SPR). A redshift and widening of the absorption peak were observed as the laser wavelength was increased. Some additional investigations were performed in order to clarify the structure of the Ag nanoparticles.     

Stability of polyvinyl alcohol-coated biochar nanoparticles in brine

This paper reports on the dispersion stability of 150 nm polyvinyl alcohol coated biochar nanoparticles in brine water. Biochar is a renewable, carbon based material that is of significant interest for enhanced oil recovery operations primarily due to its wide ranging surface properties, low cost of synthesis, and low environmental toxicity. Nanoparticles used as stabilizing agents for foams (and emulsions) or in nanofluids have emerged as potential alternatives to surfactants for subsurface applications due to their improved stability at reservoir conditions. If, however, the particles are not properly designed, they are susceptible to aggregation because of the high salinity brines typical of oil and gas reservoirs. Attachment of polymers to the nanoparticle surface, through covalent bonds, provides steric stabilization, and is a necessary step. Our results show that as the graft density of polyvinyl alcohol increases, so too does the stability of nanoparticles in brine solutions. A maximum of 34 wt% of 50,000 Da polyvinyl alcohol was grafted to the particle surface, and the size of the particles was reduced from ~3500 nm (no coating) to 350 nm in brine. After 24 h, the particles had a size of ~500 nm, and after 48 h completely aggregated. 100,000 Da PVA coated at 24 wt% on the biochar particles were stable in brine for over 1 month with no change in mean particle size of ~330 nm.     

Preformulation and formulation development of a bioactive nitroaromatic compound

The N-(butanoyloxyethyl)-4-(chloromethyl)-3-nitrobenzamide (BNB) is a nitroaromatic derivative with significant antitumor activity. Preformulation, forced degradation (distilled water, acid and base hydrolysis, oxidation, and light), and formulation studies were performed to investigate the chemical behavior of the molecule, the physicochemical properties, and the impact of formulation variables. Pharmacokinetic properties for BNB were estimated in silico. Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) containing BNB were developed by a hot melt homogenization method for parenteral administration. Degradation studies demonstrated that this compound is sensitive to hydrolysis. BNB was predicted to have a favorable absorption, distribution, metabolism, and excretion profile. The nanocarriers developed were characterized for particle size (PS?=?61 to 85 nm), polydispersity index (PI?<?0.3), zeta potential (ZP?=???22 to ??34 mV), and encapsulation efficiency (EE?=?66 to 90%) and remained stable for 30 days of storage. These studies indicated that BNB (inhibitory concentration (IC₅₀) 21.8 μM) and BNB-loaded NLC (IC₅₀ 33.7 μM) showed moderate cytotoxicity against breast cancer cell line. Blank formulations did not induce cytotoxicity and BNB-loaded SLN was able to potentiate the action of BNB (lC₅₀ 12.4 μM). BNB is a promising antitumor agent and it is possible to modulate its activity based on the particle size of the formulation.     

An Assessment of the Use of Mesoporous Silica Materials to Improve Pulsed Dipolar Spectroscopy

Protein immobilization in mesoporous silica nanoparticles has attracted much attention due to its wide range of applications. However, it remains largely unexplored how the use of mesopores can alter the spatial distribution of encapsulated biomolecules so as to improve pulsed dipolar spectroscopy sensitivity. Here, we performed electron spin resonance measurements for three different spin-labeled biomolecules (including two different peptides and a protein) encapsulated in various types of mesoporous materials differing in textural properties such as nanochannel length (e.g., 0.2–4 μm) and average pore diameter (e.g., 6–11 nm, approximately). Our results show that biomolecules are clustered somewhat upon the encapsulation into mesopores, and that due to the clustering, instantaneous diffusion plays an important role in the spin relaxation in nanochannels. The extent of molecular clustering exhibits a clear positive correlation with the length of nanochannels, whereas it shows little correlation with pore diameters. Among the materials studied, mesoporous materials with the shortest length of nanochannels are most effective to reduce spin clustering, thus suppressing the unwanted instantaneous diffusion and enhancing spin–spin relaxation time. This study has opened a possibility of improving the quality of pulsed dipolar spectroscopy with mesoporous silica nanoparticles.     

Highly hydrated poly(allylamine)/silica magnetic resin

The creation of multifunctional nanomaterials by combining organic and inorganic components is a growing trend in nanoscience. The unique size-dependent properties of magnetic nanoparticles (MNPs) make them amenable to numerous applications such as carriers of expensive biological catalysts, in magnetically assisted chemical separation of heavy metals and radionuclides from contaminated water sources. The separation of minor actinides from high-level radionuclide waste requires a sorbent stable in acidic pH, with ease of surface functionalization, and a high capacity for binding the molecules of interest. For the described experiments, the MNPs with 50 nm average size were used (size distribution from 20 to 100 nm and an iron content of 80–90 w/w%). The MNPs that have been double coated with an initial silica coating for protection against iron solubilization and oxidation in nitric acid solution (pH 1) and a second silica/polymer composite coating incorporating partially imbedded poly(allylamine) (PA). The final product is magnetic, highly swelling, containing >95% water, with >0.5 mmol amines g^?1 available for functionalization. The amine groups of the magnetic resin were functionalized with the chelating molecules diethylenetriaminepentaacetic acid (DTPA) and N,N-dimethyl-3-oxa-glutaramic acid (DMOGA) for separation of minor actinides from used nuclear fuel.     

Terahertz-based nanometrology: multispectral imaging of nanoparticles and nanoclusters in suspensions

Silica nanoparticles suspended in an organic solvent (nanosuspension) have been imaged and characterized via terahertz nanoscanning reconstructive three-dimension (3D) imaging technique. The size of individual silica nanoparticles in the suspension was quantified. In addition, the presence of nanoclusters along with their distribution in the suspension was visualized in 3D. It has also been qualitatively demonstrated that the volume fraction of solvent is significantly higher than that of the silica nanoparticles; an observation consistent with the composition of the nanosuspension in the present investigation. The measured size range of individual nanoparticles was found to be 10–12 nm, while the manufacturer’s specification indicates a nanoparticle size distribution in the range of 10 to 15 nm. However, a typical nanocluster size was determined to be 17.5 nm, thus indicating the presence of nanoparticles less than 10 nm. The nanometrology instrument used in this investigation was based on a dendrimer dipole excitation-based continuous wave terahertz source generating >?200 mW stable terahertz power.     

Synthesis and Mechanical Characterization of Nanoparticles Infused Polyurethane Foams; Statistical Analysis of Foam Morphology

Nanocomposite polyurethane foams filled with different loadings (0.1–0.7 wt.%) of nanosized silica (average grain size of about 7 or 12 nm) and organoclay were prepared by a prepolymer method, and their mechanical properties were investigated. Statistical analysis of the size distribution of the foam cells was successfully applied for the characterization of their morphology. It was shown that the developed approach provided detailed analysis of the morphology development in PU foams, including the primary cell formation and their break-up and coalescence. The degree of phase separation in nanocomposite polyurethane foams in its dependence on nanofiller type and content was calculated from the IR spectra. The presence of silica nanoparticles and organoclays gives rise to significant differences in the mechanical (stress–strain) properties of the nanocomposite polyurethane foams with respect to the pure polymer.     

Ion beam shaping of embedded metal nanoparticles by Si+ ion irradiation

Fine Co and Pt nanoparticles are nucleated when a silica sample is implanted with 400 keV Co⁺ and 1370 keV Pt⁺ ions. At the implanted range, Co and Pt react to form small Co _x Pt_(1?x) nanoparticles during Si⁺ ion irradiation at 300 °C. Thermal annealing of the pre-implanted silica substrate at 1000 °C results in the formation of spherical nanoparticles of various sizes. When irradiated with Si⁺ ions at 300 °C, particles in the size range of 5–17 nm undergo rod-like shape transformation with an elongation in the direction of the incident ion beam, while those particles in the size range of 17–26 nm turn into elliptical shape. Moreover, it is suspected that very big nanoparticles (size >26 nm) decrease in size, while small nanoparticles (size <5 nm) do not undergo any transformation. During Si⁺ ion irradiation, the crystalline nature of the nanoparticles is preserved. The results are discussed in the light of the thermal spike model.     

Magnetic permeability based diagnostic test for the determination of the canine C-reactive protein concentration in undiluted whole blood

We describe an one-step 11-min magnetic permeability based two-site immunoassay for C-reactive protein (CRP) utilizing polyclonal anti-canine CRP antibody conjugated dextran iron oxide nanoparticles (79 nm) as superparamagnetic labels and polyclonal anti-canine CRP conjugated silica microparticles (15 to 40 μm) as carriers. An inductance based magnetic permeability reader was used to detect the target analyte, CRP, in 10 μL whole blood samples, by measuring the magnetic permeability increase of the silica microparticle sediment due to immuno complex superparamagnetic nanoparticles. Measurements on standards showed a linear response between 0 and 17.5 mg/L CRP. Measurements performed on 16 whole blood samples from mixed breeds showed good correlation with a commercially available ELISA assay.     

Synthesis,characterization, and ecotoxicity of CeO<Subscript>2</Subscript> nanoparticles with differing properties

CeO₂ nanoparticles with various characteristics find an increasing number of applications in the electronic, medical, and other industries and are therefore likely released in the environment. This calls for investigations linking the physicochemical properties of these particles with their potential environmental impacts. In this study, CeO₂ nanoparticle powders were prepared using three different precursors [Ce(NO₃)₃, CeCl₃, and Ce(CH₃COO)₃] and annealing temperatures (300, 500, and 700 °C). This procedure resulted in nine different types of nanoparticles with differing size (5–90 nm), morphology, surface Ce³⁺/Ce⁴⁺ ratio, and slightly different crystal structures as characterized using transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, and X-ray diffraction measurements with Rietveld refinement. These CeO₂ nanoparticles underwent toxicity testing at concentrations up to 64 mg L^?1 using Daphnia magna. Toxic effects were observed for three particle types with EC50 values between 5 and 64 mg L^?1. No clear correlation was observed between the physicochemical properties (size, shape, oxygen occupancy, Ce³⁺/Ce⁴⁺ ratio) of the nanoparticles and their toxicity. However, toxicity was correlated with the amount of Ce remaining suspended in the test medium after 24 h. This indicated that toxic effects may depend on the colloidal stability of CeO₂ nanoparticles during the first day of exposure. Therefore, being readily suspended and remaining stable for several days in the aquatic media increases the likelihood that CeO₂ nanoparticles will cause unwanted adverse effects.     

Self-assembled silver nanoparticles: correlation between structural and surface plasmon resonance properties

We report a facile method for controllable fabrication of high-density silver nanoparticle films with a widely adjustable surface plasmon resonance (SPR) frequency, based on the gas phase cluster beam deposition. On the one hand, we can control the particle size by depositing clusters on silica substrate. Light extinction spectra of the self-assembled Ag nanoparticles with various particle sizes are characterized and show two SPRs, in which a SPR exhibits a redshift from less 400 nm to more than 570 nm with an increase in the particle size, whereas the other shows a slight position shifting. On the other hand, the inter-particle distance of the self-assembled Ag nanoparticles can also be controlled by depositing clusters on silica glass coated with Formvar film, and the SPR wavelength shows a redshift from <400 nm to more than 560 nm, which can be attributed to the increase of the fraction of closely spaced nanoparticle pairs that are near-field coupled with the deposition mass. The size and coverage-dependent SPR properties are also compared with the results from the discrete dipole approximation calculations. The present method of tailoring metallic microstructures could find important applications in plasmonics.     

Silver–titanium dioxide nanocomposites as effective antimicrobial and antibiofilm agents

Recent studies have revealed the existence of liver cancer stem cells (CSCs). Therefore, there is an urgent need for new and effective treatment strategies specific to liver CSCs. In this work, the poly(d,l-lactide-coglycolide) nanoparticles containing paclitaxel were prepared by emulsification-solvent evaporation method. The nanoparticles decorated with anti-CD133 antibody, termed targeted nanoparticles, were prepared by carbodiimide chemistry for liver CSCs. The physicochemical characteristics of the nanoparticles (i.e., encapsulation efficiency, particle size distribution, morphology, and in vitro release) were investigated. Cellular uptake and accumulation in tumor tissue of nanoparticles were observed. To assess anti-tumor activity of nanoparticles in vitro and in vivo, cell survival assay and tumor regression study were carried out using liver cancer cell lines (Huh7 and HepG2) and their xenografts. Particle size of targeted nanoparticles was 429.26 ± 41.53 nm with zeta potential of ?11.2 mV. Targeted nanoparticles possessed spherical morphology and high encapsulation efficiency (87.53 ± 5.9 %). The accumulation of targeted nanoparticles depends on dual effects of passive and active targeting. Drug-loaded nanoparticles showed cytotoxicity on the tumor cells in vitro and in vivo. Targeted nanoparticles resulted in significant improvement in therapeutic response through selectively eliminating CD133 positive subpopulation. These results suggested that the novel nanoparticles could be a promising candidate with excellent therapeutic efficacy for targeting liver CSCs.     

Gyroscopic behavior exhibited by the optical Kerr effect in bimetallic Au–Pt nanoparticles suspended in ethanol

The modification in the third-order nonlinear optical response exhibited by rotating bimetallic Au–Pt nanoparticles in an ethanol solution was analyzed. The samples were prepared by a sol–gel processing route. The anisotropy associated to the elemental composition of the nanoparticles was confirmed by high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy measurements. The size of the nanoparticles varies in the range from 9 to 13 nm, with an average size of 11 nm. Changes in the spatial orientation of the nanomaterials automatically generated a variation in their plasmonic response evaluated by UV–Vis spectroscopy. A two-wave mixing experiment was conducted to explore an induced birefringence at 532 nm wavelength with nanosecond pulses interacting with the samples. A strong optical Kerr effect was identified to be the main responsible effect for the third-order nonlinear optical phenomenon exhibited by the nanoparticles. It was estimated that the rotation of inhomogeneous nanostructures can provide a remarkable change in the participation of different surface plasmon resonances, if they correspond to multimetallic nanoparticles. Potential applications for developing low-dimensional gyroscopic systems can be contemplated.     

Effects of iron oxide nanoparticles on polyvinyl alcohol: interfacial layer and bulk nanocomposites thin film

Iron oxide (α-phase) nanoparticles with coercivity larger than 300 Oe have been fabricated at a mild temperature by an environmentally benign method. The economic sodium chloride has been found to effectively serve as a solid spacer to disperse the iron precursor and to prevent the nanoparticles from agglomeration. Higher ratios of sodium chloride to iron nitrate result in smaller nanoparticles (19 nm for 20:1 and 14 nm for 50:1). The presence of polyvinyl alcohol (PVA) limits the particle growth (15 nm for 20:1 and 13 nm for 50:1) and favors nanoparticle dispersion in polymer matrices. Obvious physicochemical property changes have been observed with PVA attached to the nanoparticle surface. With PVA attached to the nanoparticle surface, the nanoparticles are found not only to increase the PVA cross-linking with an increase in melting temperature but also to enhance the thermal stability of the PVA. The nanoparticles are observed to be uniformly dispersed in the polymer matrix. Scanning electron microscopy (SEM) microstructure also shows an intermediate phase with a strong interaction between the nanoparticles and the polymer matrices, arising from the hydrogen bonding between the PVA and hydroxyl groups on the nanoparticle surface. The addition of nanoparticles favors the cross-linkage of the bulk PVA matrices, resulting in a higher melting temperature, and an enhanced thermal stability of the polymer matrix.     

Lipid-based nanoparticles as drug delivery system for paclitaxel in breast cancer treatment

Paclitaxel (PTX) is a well-known antitumor drug, widely utilized in the treatment of breast, ovarian, head, and neck tumors, among others. The low aqueous solubility (< 1.0 μg/mL; log P = 3.96) limits its use by intravenous route, and alternatives found for the marketed products are associated with high toxicity. Incorporation of PTX into lipid nanocarriers has been considered an interesting nontoxic alternative for this route, but drug loading is usually low. This study aimed to analyze the influence of the lipid composition and three different lipid nanosystems—solid lipid nanoparticles, nanostructured lipid carriers (NLCs), and nanoemulsion—in PTX encapsulation and its biological response. The three proposed systems were prepared by hot melt homogenization followed by ultrasonication. Among the blank formulations first prepared, NLC had the smallest size (74 ± 1 nm), with negative zeta potential (? 11.4 ± 0.1 mV). The incorporation of 0.10 mg/mL PTX into this NLC formulation yielded high and stable encapsulation (0.089 ± 0.003 mg/mL), also supported by polarized light microscopy and differential scanning calorimetry curves. NLC-PTX was very effective against MCF-7 (IC50 25.33 ± 3.17 nM) and MDA-MB-231 breast cancer cell lines (IC50 2.13 ± 0.21 nM), compared to free PTX (IC50 > 500 nM). In addition, no significant cytotoxicity was found against fibroblast cells. Taken together, these results demonstrated that PTX was successfully incorporated into NLC with appropriate physicochemical characteristics for intravenous administration, suggesting that the use of NLC as vehicle to incorporate PTX may be a promising strategy in the treatment of breast cancer.     

Tunable Upconversion Emissions from Lanthanide-doped Monodisperse β-NaYF4 Nanoparticles

We report upconversion multicolor tuning based on uniform β-NaYF₄:Yb/Tm/Er nanoparticles. The as-synthesized nanoparticles with an average diameter of 25 nm are well dispersed in a wide range of nonpolar solvents including hexane, cyclohexane, dichloromethane, and toluene. These nanoparticles show intense upconversion emissions and the color output can be precisely modulated by adjusting activator ratios of Tm³⁺ to Er³⁺. Dopant-concentration dependent emission properties of the triply doped particle system are also investigated. In addition, we demonstrate that these nanoparticles can be readily transferred to polar solvents such as ethanol and water by growing a thin silica layer (10 nm) around the particles, providing potential applications in biological labeling and imaging.     

Rapid synthesis of SiO<Subscript>2</Subscript> by ultrasonic-assisted Stober method as controlled and pH-sensitive drug delivery

In this paper, the monodisperse silica nanoparticles were prepared by ultrasonic-assisted Stober method, and it explained that the ultrasonic cavitation effect shortened the reaction time from the original hours to f5 min. The effects of ultrasonic time, ultrasonic power, and stirring speed on the morphology, composition, and specific surface area of silica nanoparticles were investigated by field emission electron microscopy (FE-SEM). The results showed that nanoparticles with the best dispersity and the most uniform morphology were obtained under the optimized conditions (ultrasonic time is 5 min, ultrasonic power is 160 W, and the magnetic stirring speed is 999 rpm). The phase composition of SiO₂ was characterized by high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), nano-size/zeta potential analyzer, and Fourier transform infrared spectroscopy (FT-IR). It showed that all typical peaks of samples are in line with the SiO₂ spectrum, the particle size distribution and zeta potential value of the silica is 615?±?35.6 nm and 59.87?±?0.91 mv, respectively, which further verified that the spherical silica nanoparticles with good dispersity can be synthesized in a very short time. Hemolysis test showed that nano-SiO₂ had high blood compatibility and biocompatibility when its concentration was less than 1 mg/mL. Doxorubicin (DOX·HCl) was regarded as a drug model to investigate the drug loading capacity of synthesized SiO₂; the results showed that the drug loading capacity and encapsulation efficiency reached 42.6?±?1.2 and 85.2?±?2.5%, respectively. Furthermore, the drug release experiments fitted well with the Higuichi equation with correlation coefficient (R²) of 0.9984, which further confirmed that the SiO₂/DOX drug delivery system has the controlled release property, and it also displayed pH-responsive behavior (at 96 h, the cumulative release of SiO₂/DOX in PBS solution with pH 7.4, 6.5, and 5.0 was 48.33, 62.31, and 94.86%, respectively). Therefore, this paper provides the possibility for developing more effective, safer, and more targeted controlled drug carriers.