Narrow Size Distribution Research Articles

Preparation of novel highly stable fluorinated microporous polyketone networks through direct C–H arylation polycondensation for efficient natural gas separation

Two novel hyper-cross-linked fluorinated microporous polyketone networks (FMPN-1 and FMPN-2) with permanent porosity and narrow pore size distribution were synthesized via a facile “one-step” polycondensation between the trifluoroacetophenone-based monomers and 1,3,5-triphenylbenzene. The result polymers were investigated by FTIR, solid state NMR, EDX, XRD, TGA, SEM, and TEM et al. The geometry configurations difference of building blocks resulted in the polyketone networks exhibiting the BET special surface areas from 622 to 706 m2 g−1 and total volume from 0.58 to 0.66 cm3 g−1. What's more, ideal adsorbed solution theory (IAST) analysis showed that the two polymers possessed good C3H8/CH4, C2H6/CH4 selectivities at 298K/1 bar. Together with the excellent thermal and physicochemical stabilities, the microporous fluorinated polyketone networks obtained in this work showed promising applications in adsorption/separation for C1–C3 hydrocarbons.

Modification of Silica with Sucrose and Ammonium Fluoride Agents: A Facile Route to Prepare Supports of Iridium Catalysts for Hydrogenation Reaction.

Mesoporous silica materials were synthesized using inexpensive and environmentally friendly sucrose as a porogeneous agent. It was found that the presence of sucrose and the products of its chemical transformation during synthesis (e.g., furfural polymer) significantly affected the structure of the obtained porous silica. The influence of synthesis conditions (pH, temperature, time) on the textural properties of the final materials was determined. Samples obtained in an acidic medium, at pH = 1, and treated at room temperature, yielded products with a large surface area and a narrow pore size distribution in the range of 2-5 nm, while the synthesis at pH = 8 allowed for the formation of mesoporous systems with pores in the range of 14-20 nm. To generate acidity, the silicas were modified with an ammonium fluoride solution and then used as supports for iridium catalysts in a hydrogenation reaction, with toluene as a model hydrocarbon. The influence of parameters such as specific surface area, support acidity, and iridium dispersion on catalytic activity was determined. It was shown that modification with sucrose improved the porous structure, and NH4F modification generated acidity. These parameters favored better reducibility and dispersion of the active phase, resulting in higher activity of the catalysts in the studied hydrogenation reaction.

A comprehensive study on the phase composition, mechanical properties and stability of Li4SiO4-Li2ZrO3 biphasic ceramics

Lithium orthosilicate (Li4SiO4) is regarded as a candidate for tritium breeding in fusion reactors. In this study, the Li4SiO4-Li2ZrO3 biphasic was developed to improve the sinterability, density, and mechanical properties of Li4SiO4. The Li4SiO4-xLi2ZrO3 (x = 0.5, 1) composite powders were prepared using solid-state reaction via in-situ method. Li6Zr2O7 existed in the ceramic powders at low calcination temperatures. When the calcination temperature was increased to 900 °C, Li6Zr2O7 was transformed into Li2ZrO3 due to the decomposition of Li6Zr2O7 at high temperatures. The TEM observation confirmed that the powders consisted of Li4SiO4 and Li2ZrO3. The Li4SiO4 and Li4SiO4-xLi2ZrO3 (x = 0.5, 1) pebbles were fabricated by the sol-gel method. The measurement results showed that the pebbles had a narrow size distribution and fine sphericity. The density of Li4SiO4-Li2ZrO3 pebbles reached 96.01% of the theoretical density when it was sintered at 1000 °C for 4 h. Compared with the Li4SiO4, the grain size of ceramic pebbles was significantly reduced. Owing to decreased grain size, 139.0 N crush load for the pebbles and 92.4 MPa bending strength for the sintered bodies were achieved. Besides, the ceramics with the Li4SiO4 to Li2ZrO3 ratio of 2: 1 exhibited preferable mechanical properties. Further, to investigate the chemical stability of biphasic ceramics, the structure and mechanical properties were examined under high temperatures and continuous inert gas purging, simulating the working condition of fusion reactors. It was shown that there was almost no change in phase composition and grain size after purging for 60 h at 650 °C. For the mechanical properties, the crush load was decreased initially due to the cracking in the surface region of the ceramic and then increased because the cracking was recovered.

Integration of Melt Electrowritten Polymeric Scaffolds and Bioprinting for Epithelial Healing via Localized Periostin Delivery.

Management of skin injuries imposes a substantial financial burden on patients and hospitals, leading to diminished quality of life. Periostin (rhOSF), an extracellular matrix component, regulates cell function, including a proliferative healing phase, representing a key protein to promote wound healing. Despite its proven efficacy in vitro, there is a lack of scaffolds that facilitate the in situ delivery of rhOSF. In addition, there is a need for a scaffold to not only support cell growth, but also to resist the mechanical forces involved in wound healing. In this work, we synthesized rhOSF-loaded mesoporous nanoparticles (MSNs) and incorporated them into a cell-laden gelatin methacryloyl (GelMA) ink that was bioprinted into melt electrowritten poly(ε-caprolactone) (PCL) microfibrous (MF-PCL) meshes to develop mechanically competent constructs. Diffraction light scattering (DLS) analysis showed a narrow nanoparticle size distribution with an average size of 82.7 ± 13.2 nm. The rhOSF-loaded hydrogels showed a steady and controlled release of rhOSF over 16 days at a daily dose of ∼40 ng/mL. Compared with blank MSNs, the incorporation of rhOSF markedly augmented cell proliferation, underscoring its contribution to cellular performance. Our findings suggest a promising approach to address challenges such as prolonged healing, offering a potential solution for developing robust, biocompatible, and cell-laden grafts for burn wound healing applications.

Development and antioxidant evaluation of mango leaf (Mangifera indica L.) extract loaded silk fibroin nanoparticles

The main antioxidant polyphenol compounds in the mango (Mangifera indica L.) leaf extract are susceptible to environmental degradations. Thus, in biomedical applications, the mango leaf extract is commonly encapsulated in a carrier. However, most studies employed the synthetic carrier materials that could affect the human health, and the complicated formulation procedure that could hinder the scalability. Therefore, this work, for the first time, explored the use of silk fibroin (an FDA-approved biomaterial), in nanoparticles platform, to encapsulate and deliver the mango leaf extract, utilizing the simple coacervation preparation method. Initially, the mango leaf ethanolic extract was obtained through maceration, resulting in a total phenolic content of 76.39 ± 0.14 mg GAE/g DPW and a notably high antioxidant activity (IC50 = 6.872 ± 0.512 μg/mL). Subsequently, silk fibroin nanoparticles loaded with the extract were developed by the coacervation technique. Depending on the fibroin content, these nanoparticles exhibited an appropriate size range of 500–800 nm with narrow size distributions, a spherical shape with smooth surfaces, a dominant silk-II crystalline structure, a drug entrapment efficiency exceeding 70%, and retained the main biomarker mangiferin. Moreover, the phenolic-compounds release profiles from the particles followed the three-step process, the first burst-release step, the second sustained-release step, and the third degradation step. The particles were also non-toxic to the erythrocytes and the human embryonic kidney HEK-293 cell line. Lastly, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay demonstrated that the antioxidant activity of the mango leaf extract was preserved within the extract-loaded nanoparticles. The results suggested that the silk fibroin nanoparticles could be a potential platform to effectively encapsulate and deliver the mango leaf extract for biomedical purposes.

Optimization of atorvastatin and quercetin-loaded solid lipid nanoparticles using Box-Behnken design.

Aim: The study explores the synergistic potential of atorvastatin (ATR) and quercetin (QUER)- loaded solid lipid nanoparticles (SLN) in combating breast cancer. Materials & methods: SLNs were synthesized using a high-shear homogenization method and optimized using Box-Behnken design. The SLNs were characterized and evaluated for their in vitro anticancer activity. Results: The optimized SLN exhibited narrow size distribution (PDI=0.338±0.034), a particle size of 72.5±6.5 nm, higher entrapment efficiency (<90%), sustained release and spherical surface particles. The in vitro cytotoxicity studies showed a significant reduction in IC50 values on MDA-MB-231 cell lines. Conclusion: We report a novel strategy of repurposing well-known drugs and encapsulating them into SLNs as a promising drug-delivery system against breast cancer.

In situ photodeposition of ultra-small palladium particles on TiO2.

In situ and operando investigation of photocatalysts plays a fundamental role inunderstanding the processes of active phase formation and the mechanisms ofcatalytic reactions, which is crucial for the rational design of more efficient materials. Using a custom-made operando photocatalytic cell, an in situ procedure to follow the formation steps of Pd/TiO2 photocatalyst by synchrotron-based X-ray absorption spectroscopy (XAS) is proposed. The procedure resulted in the formation of ∼1 nm Pd particles with a much narrower size distribution and homogeneous spreading over TiO2 support compared with the samples generated in a conventional batch reactor. The combination of in situ XAS spectroscopy with high-angle annular dark-field scanning transmission electron microscopy demonstrated the formation of single-atom Pd(0) sites on TiO2 as the initial step of the photodeposition process. Palladium hydride particles were observed for all investigated samples upon exposure to formic acid solutions.

Effects of continuous millifluidic process on the physicochemical properties and freeze-drying of cloxacillin benzathine-loaded nanocapsules

Poly-ɛ-caprolactone nanocapsules loading cloxacillin benzathine (CLOXB-NC) were produced by batch-nanoprecipitation (BNP) and millifluidic continuous flow (CNP) methods. Regarding the CNP, a new millifluidics device was constructed, and the effects of flow rate and organic to aqueous phase proportions (OP/AP) were investigated. Dynamic light scattering (DLS) and atomic force microscopy (AFM) were used to characterize the NC size distribution and morphology, respectively. CLOXB was quantified by high-performance liquid chromatography (HPLC) to determine encapsulation efficiency (EE) and loading yield. DLS results show that unloaded NC can be produced with a narrow size distribution by CNP with an AP flow of 77 mL/min with an OP/AP of 1:2 by CNP. Based on optimized conditions, CLOXB-NC was produced and compared with the BNP method. CLOXB-NC produced by CNP was spherical and presented a higher EE and a smaller distribution size than NC produced by BNP. Freeze-drying was carried out under two freezing conditions, −20 °C and fast frozen in liquid nitrogen (−196 °C). DLS, HPLC, AFM, SEM, and thermal analysis were applied to characterize the freeze-dried formulations. Both freezing conditions were satisfactory for producing CLOXB-NC powders using sucrose as a cryoprotectant. After powder resuspension, CLOXB-NCs frozen in liquid nitrogen showed superior drug leakage than samples frozen at −20 °C. Interestingly, CLOXB-NCs produced by CNP tolerated the freeze-drying process better. NC loading CLOXB (0.5 mg/mL) produced by CNP and frozen at −20 °C with 10 % (p/v) of sucrose demonstrated Sf/Si closest to 1, less drug leakage, fluffy and porous cake. In conclusion, this novel approach to producing NC in continuous flow in a simple and accessible millifluidic device represents an innovative process to improve NC's aptness to withstand mechanical stress during the freeze-drying process.

Effect of “corona-core” structuring of poly(1-vinyl-1,2,4-triazole)–poly(acrylic acid)-Ag(I) interpolymer complexes on the radiation-induced preparation and stability of silver nanoparticles

Interpolymer complexes (IPC) of water-soluble polymers can be promising matrices for the synthesis of metal colloids. In this work, silver nanoparticles were obtained via radiation-induced reduction (under X-ray irradiation) of complexes based on poly (1-vinyl-1,2,4-triazole) (PVT) and poly (acrylic acid) (PAA) containing Ag+ ions. Particular attention was paid to the role of the supramolecular structure in the formation of nanoparticles. Combined dynamic light scattering and electrophoretic mobility measurements have revealed that, in pH range 5.5–7, micro-scale aggregates of the initial PVT-PAA-Ag(I) IPC transform into nano-sized particles consisting of a PVT-Ag(I) core electrostatically stabilized by PAA loops and tails forming a corona. It was explicitly demonstrated for the first time that such transformation of IPC aggregates can significantly enhance the efficiency of AgNPs formation. In particular, using UV-VIS spectroscopy and transmission electron microscopy, we have shown that at pH 7.0 the core of the “corona-like” form of the PVT-PAA-Ag(I) complex ensures the radiation-induced generation of AgNPs with a narrow size distribution due to the strong affinity of triazole groups to the metal surface. At the same time, the localization of the excessive negatively charged carboxylate groups in the outer part of the complex provides a long-term colloidal stability of the prepared AgNPs.

Surface anchoring requirements for vanadia clusters on titanium oxide surfaces and their impact on activity for oxidative dehydrogenation of ethanol

Titanium oxide site requirements for the anchoring of catalytically active forms of dispersed vanadia species are investigated. Using a series of oxygen-modified titanium nitride materials, we systematically modify the available vanadia-anchoring moieties on the titanium-bearing support surface. This strategy in turn results in a very narrow size distribution of well-dispersed vanadia clusters anchored on the support. This synthesis technique ensures that only highly dispersed vanadia is present on the catalyst surface even at nominal monolayer coverages. A deeper insight into the catalytic behavior for ethanol partial oxidation of the active vanadia species is obtained by comparing intrinsic kinetic and thermodynamic parameters of kinetically relevant reaction steps (heat of ethanol adsorption, hydrogen abstraction activation energy, and the energetics of catalyst reoxidation). It is found that these parameters are dependent on the relative amount of oxygen in the titanium-bearing support and the resulting distribution of vanadia species, which validates the premise of a potential participation of lattice oxygen atoms of the titania support into the catalytic activity of active vanadia species.

Design of a continuous ion exchange process in battery metals recycling: From single column experiments towards a simulated moving bed configuration

In hydrometallurgical recovery of LIB metals, ion exchange (IX) has hitherto played only a minor role. Separation experiments were conducted in single laboratory-scale IX columns with the aim of laying the foundation for a continuously operated multicolumn IX process similar to a simulated moving bed (SMB) configuration. In this study, the initial process developed earlier was improved by reducing the number of process steps and external streams. The desorption step with oxalate solution was examined in single-column batch experiments to ensure complete desorption of iron in the proposed continuous multicolumn IX process. Additionally, the volume flowrates were adjusted to achieve acceptable switch times of 25 min in an SMB configuration. It was found that the bead size of the resin is a critical factor in IX recovery of battery metals. The raffinate purity for the case of processing 2.5 BV lithium-ion battery waste leachate (LIBWL) improved from 97.2 % to 99.8 % when the resin bead size was reduced from 0.55 ± 0.05 mm to 0.4 ± 0.04 mm and a narrower bead size distribution. The LIBWL feed concentration was varied to mimic the dilution of fresh feed in an SMB set-up. The percentage recovery of Co and Ni decreased from 93.7 % and 96.6 % to 80.8 % and 89.4 %, respectively, when the LIBWL was diluted. This was a result of the decrease in concentration of impurity metals in the feed. Less impurity metals were sorbed and consequently, more ion exchange sites were available for the sorption of the target metals, which enhanced the retention of Co and Ni. The results were used to develop an IX column operation strategy and to suggest an initial SMB design. The multicolumn configuration presented in this work offers great potential for continuous production of high-purity Li, Ni and Co-containing raffinate (> 99.5 %).

Architecting ultra-thin SiO2 shell for high magnetic performance of Fe3O4 nanoparticles for biomedical applications

This research focuses on the architectural design of the silica shell on the Fe3O4 nanoparticle to precisely control and minimize its thickness, with the aim of achieving a final product with optimal saturation magnetization (Ms) for biomedical applications. A rapid and facile microwave-assisted synthesis method was developed for the synthesis of Fe3O4@SiO2 and Fe3O4@SiO2@NH2 core–shell nanoparticles with ultra-thin SiO2 shells and excellent magnetic performance. The particle size distribution of the Fe3O4@SiO2 nanoparticles was in the range of 15–35 nm, with a mean particle size of approximately 21 nm. The mean thickness of the SiO2 shells on the Fe3O4 cores was found to be 3 nm. FTIR analysis also confirmed the successful silica coating on Fe3O4 nanoparticles and the successful amino-functionalization of silica-coated Fe3O4 nanoparticles. The Ms of Fe3O4, Fe3O4@SiO2, and Fe3O4@SiO2@NH2 nanoparticles were found to be 64.4, 59.8, and 52.4 emu/g, respectively. It has been confirmed that the ultra-thin SiO2 coating has a negligible effect on the magnetic characteristics of the nanoparticles. The developed microwave-assisted synthesis method in this study not only provides an interesting, rapid, and facile synthesis route but also results in a product with a narrow particle size distribution, an ultra-thin SiO2 shell, favorable magnetic properties, and improved cell compatibility, which may be used in several different applications, particularly biomedical applications.

Bimetallic nanoparticles with sulfated galactan eliminate Vibrio parahaemolyticus in shrimp Penaeus vannamei

Bimetallic (Au/Ag) nanoparticles (BNPs) have shown enhanced antibacterial activity compared to their monometallic counterparts. Sulfated galactans (SG) are a naturally occurring polymer commonly found in red seaweed Gracilaria fisheri. They are biocompatible and biodegradable and environmentally friendly. In this study, we utilized SG in combination with BNPs to develop composite materials that potentially enhance antibacterial activity against shrimp pathogens Vibrio parahaemolyticus and Vibrio harveyi, compared to BNPs or SG alone. BNPs were coated with sulfated galactan (SGBNPs) and characterized using UV–vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, zeta potential, and transmission electron microscopy (TEM). UV–vis spectroscopy analysis revealed that the surface plasmon peaks of BNPs and SGBNPs appeared at 530 nm and 532 nm, respectively. Zeta potential measurements showed that SGBNPs had a negative charge of −32.4 mV, while the BNPs solution had a positive charge of 38.7 mV. TEM images demonstrated the spherical morphology of both BNPs and SGBNPs with narrow size distributions (3–10 nm). Analysis of the FTIR spectra indicated that SG maintained its backbone structure in SGBNPs, but some functional groups were altered. Notably, SGBNPs showed superior antimicrobial and antibiofilm activities against V. parahaemolyticus and V. harveyi compared to SG and BNPs. Furthermore, treatment with SGBNPs significantly down-regulated the expression of virulence-related genes (toxR, cpsQ, and mfpA) for V. parahaemolyticus 3HP compared to the respective control, bacteria treated with BNPs or SG. Diets supplemented with SGBNPs, BNPs, or SG showed no detrimental impact on the growth of shrimp Penaeus vannamei. Shrimp fed with SGBNPs-supplemented feed showed significantly higher survival rates than those fed with BNPs-supplemented feed when infected with 3HP after being on the supplemented feed for seven days and a subsequent number of fifteen days. These findings collectively demonstrate the benefit of using SG capped Au–Ag BNPs as an antibacterial agent for the prevention and control of Vibrio sp. Infection in shrimp while reducing the risk of environmental contamination.

Polyethersulfone mixed matrix membrane with abundant sponge pores for high‐separation performance with high flux retention and cycling stability

AbstractIn recent years, a series of high‐performance ultrafiltration membranes have been developed, but maintaining high flux and high pollutant retention rate without sacrificing service life remains a long‐standing challenge. In this study, a porous polyethersulfone ultrafiltration membrane enriched with ZIF‐8 and TiO2 additives is prepared based on a non‐solvent induced phase separation method. During the phase transition process, the addition of organic nanocrystals ZIF‐8 and inorganic nanocrystals TiO2 delayed the phase transition rate, resulting in the transformation of the polyethersulfone modified membrane from a finger‐like pore structure to a sponge‐like pore structure. Compared to other structures, the sponge‐like modified membrane has a uniform and narrow pore size distribution, fewer surface defects, stable retention performance, and can simultaneously improve membrane permeability and mechanical strength. Therefore, the polyethersulfone modified membrane with a sponge‐like pore structure prepared in this research exhibits high flux for small molecules and good retention rate for large molecules. Long‐term cycling stability tests of the modified membrane shows high retention rate (over 98%), high flux, long service life, and good cycling stability for solute molecules. The study indicates that the prepared polyethersulfone modified membrane has high potential for application in relevant environmental separation processes.

Green synthesis of gadolinium-doped bismuth oxide nanoparticles: Exploring their biological and photocatalytic activities

Coldeniaprocumbens leaf extract assisted green synthesis of gadolinium-doped bismuth oxide nanoparticles (Gd-Bi2O3NPs) was demonstrated. Electron microscopic analysis indicated that the Gd-Bi2O3 has nanoflake-like shape with a narrow size distribution of 20–30 nm. FT-IR and XRD analysis confirmed the doping of Gd-ions into Bi2O3 crystal structure. The UV–vis spectral investigation was carried to know the characteristic absorbance peaks and the band gap of Gd-Bi2O3 samples. The antibacterial activity of Gd-Bi2O3 samples was evaluated against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Enterococcus faecalis. The larvicidal activity of Gd-Bi2O3 samples was also evaluated against the mosquito larvae of Aedesaegypti and Aedesalbopictus. Furthermore, the photocatalytic potential of Gd-Bi2O3 samples has been evaluated using malachite green (MG) and methylene blue (MB) dyes under visible light radiation. The green Gd-Bi2O3 samples displayed potent antibacterial, larvicidal, and photocatalytic activities, making them a promising candidate for environmental remediation applications.

Binding Angle Robustness of Plasmonic Nanorod Dimer Resonances

AbstractNarrow gaps between coupled plasmonic nano‐particles show strong optical field enhancements and spectrally adjustable resonance positions, making them attractive for surface enhanced spectroscopies. Gold nanorod dimers formed from nanorod solutions with narrow size distributions are intensely investigated in this context. However, the binding angle of rods coupled at their end faces is usually not controllable. Surprisingly, it is observed that this has only little effect on field enhancement and resonance energies. In this work, gold nanorod dimers are investigated by mapping their plasmon resonances using electron energy‐loss spectroscopy in a scanning transmission electron microscope. For a wide range of dimer orientations, a negligible influence of the angle between the two rods on the bonding and antibonding longitudinal dipole resonances is confirmed, in good agreement with numerical simulations. The results are interpreted via the predominant end‐coupling of the individual nanorod's plasmonic modes, as illustrated by an analytical charge coupling model. In addition, the simulations emphasize that conclusions from experimental data on the gap morphology on the size range of one nanometer can be ambiguous. In any case, the full understanding of the angle‐invariant resonances of nano‐rod dimers can further promote their controlled application in surface enhanced spectroscopy or ‐sensing.

Characterization of Copper nanoparticles obtained in AOT reverse micelles using flavonoids as a reducing agent

Purpose of the study. To characterize copper nanoparticles obtained in reverse micelles of sodium bis-(2-ethylhexyl)-sulfosuccinate (AOT) using flavonoids: quercetin and rutin in comparison with traditional reducing agents - sodium borohydride and hydrazine. Methods. Chemical synthesis of copper nanoparticles, spectrophotometry to determine the maximum of the plasmon absorption band of copper nanoparticles, electron transmission microscopy. Results. The reduction of copper ions using flavonoids – quercetin and rutin – confirmed the possibility of obtaining copper nanoparticles in the Cu+2/AOT/isooctane system (AOT is sodium bis-(2-ethylhexyl)-sulfosuccinate, an anionic surfactant that forms the micelle shell). During the formation of nanoparticles, “plasmonic” absorption bands were observed in the electronic spectra in the region of 400-440 nm. In the case of the traditional reducing agent, sodium borohydride, absorption is observed in the region of (439 ± 3) nm, which can also be attributed to the “plasmonic band” of copper nanoparticles, but its intensity is very low, which indicates the formation of a small amount of copper nanoparticles. Using transmission electron microscopy. The average size of copper nanoparticles was determined: 7.1, 8.2 and 18.5 nm in the case of quercetin, rutin and hydrazine, respectively. From the histograms constructed from the results of electron transmission microscopy, it follows that the use of flavonoids as reducing agents makes it possible to reduce the average size of copper nanoparticles and narrow their size distribution. Conclusion. Copper nanoparticles obtained in a reverse micellar solution of AOT in iso-octane using the flavonoids quercetin and rutin as a reducing agent have an average size of 7-8 nm and a narrower size distribution compared to reduction with hydrazine.

Silver-nanoparticle-modified nanocellulose synthesized by pyroligneous acid: cytotoxicity towards HaCat cells

In the present study, pyroligneous acid, also known as wood vinegar, has been employed as reducing and stabilizing agent in the synthesis of silver nanoparticles (AgNPs) anchored on nanocellulose (NC). The idea is to confer the latter bactericidal properties for its typical uses such as in cosmetics and food-packing. It has been demonstrated that AgNPs can be directly produced onto NC in one-pot fashion while dramatically enhancing the kinetics of AgNPs synthesis (2 h for reaction completion) in comparison to the NC-less counterpart (10 days for reaction completion). Furthermore, NC allowed for a narrower size distribution of AgNPs. NC-supported and non-supported AgNPs had sizes of 5.1 ± 1.6 nm and 16.7 ± 4.62 nm, respectively. Immortalized human keratinocytes (HaCat) cells were then employed as model to evaluate the cytotoxicity of the AgNPs-NC compound. The latter was found not to impact cell proliferation at any formulation, while decreasing the viability by only 6.8% after 72 h. This study contributes to the development of more environmentally benign routes to produce nanomaterials and to the understanding of their impact on cells.

Sustained Delivery of Rifampicin Nanoformulation Administration Intravitreally Into Rabbit Eyes for Ocular Tuberculosis.

Diagnosis and treatment of ocular tuberculosis is very challenging. It poses a significant and potential management dilemma after diagnosis as a primary, active, or secondary infection. The higher amounts of orally administered antitubercular drugs are needed to achieve the therapeutic concentration in the eye, which may lead to a higher risk of side effects. However, the intravitreal administration of drugs is not practiced because of the frequent administration of the injections. This study was carried out to develop, optimize, and characterize rifampicin-loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles to make them sustained release followed by the direct administration of plain rifampicin and rifampicin nano-formulations in the vitreous of rabbit eyes. Both groups were comparatively assessed for the sustained delivery of the two preparations in the vitreous and their systemic toxicity. The characteristics of rifampicin-loaded nanoparticles were 786 nm in size with narrow size distribution along with a zeta potential of -12 mV. The drug encapsulation efficiency and loading capacity were 67.68% w/w and 42.28% w/w, respectively. The four New Zealand white rabbits were divided into two groups and given plain rifampicin (50µl volume) and PLGA nanoformulations of rifampicin (50µl volume) in each eye. In vivo, rifampicin-loaded PLGA nanoparticles produced sustained release of rifampicin for a week, even obtaining the 0.51 µg/ml levels on the seventh day in vitreous against negligible levels after one day for free rifampicin. The Cmax levels for free Rifampicin and Rifampicin nanoparticles were 0.44 µg/ml and 1.86 µg/ml, respectively. In this experimental proof-of-concept study, we have found that rifampicin-loaded PLGA nanoparticles released rifampicin in a sustained manner for up to seven days compared to free drugs only for one day into the vitreous. The intravitreal-administered drug did not reach systemic circulation.

Comparing novel small-angle x-ray scattering approaches for absolute size and number concentration measurements of spherical SiO2 particles to established methods

Biomedical analytical applications, as well as the industrial production of high-quality nano- and sub-micrometre particles, require accurate methods to quantify the absolute number concentration of particles. In this context, small-angle x-ray scattering (SAXS) is a powerful tool to determine the particle size and concentration traceable to the Système international d’unités (SI). Therefore, absolute measurements of the scattering cross-section must be performed, which require precise knowledge of all experimental parameters, such as the electron density of solvent and particles, whereas the latter is often unknown. Within the present study, novel SAXS-based approaches to determine the size distribution, density and number concentrations of sub-micron spherical silica particles with narrow size distributions and mean diameters between 160 nm and 430 nm are presented. For the first-time traceable density and number concentration measurements of silica particles are presented and current challenges in SAXS measurements such as beam-smearing, poorly known electron densities and moderately polydisperse samples are addressed. In addition, and for comparison purpose, atomic force microscopy has been used for traceable measurements of the size distribution and single particle inductively coupled plasma mass spectrometry with the dynamic mass flow approach for the accurate quantification of the number concentrations of silica particles. The possibilities and limitations of the current approaches are critically discussed in this study.