Bead Mill Research Articles

Novel Sustained-Release Drug Delivery System for Dry Eye Therapy by Rebamipide Nanoparticles.

The commercially available rebamipide ophthalmic suspension (CA-REB) was approved for clinical use in patients with dry eye; however, the residence time on the ocular surface for the traditional formulations is short, since the drug is removed from the ocular surface through the nasolacrimal duct. In this study, we designed a novel sustained-release drug delivery system (DDS) for dry eye therapy by rebamipide nanoparticles. The rebamipide solid nanoparticle-based ophthalmic formulation (REB-NPs) was prepared by a bead mill using additives (2-hydroxypropyl-β-cyclodextrin and methylcellulose) and a gel base (carbopol). The rebamipide particles formed are ellipsoid, with a particle size in the range of 40–200 nm. The rebamipide in the REB-NPs applied to eyelids was delivered into the lacrimal fluid through the meibomian glands, and sustained drug release was observed in comparison with CA-REB. Moreover, the REB-NPs increased the mucin levels in the lacrimal fluid and healed tear film breakup levels in an N-acetylcysteine-treated rabbit model. The information about this novel DDS route and creation of a nano-formulation can be used to design further studies aimed at therapy for dry eye.

The Intravitreal Injection of Lanosterol Nanoparticles Rescues Lens Structure Collapse at an Early Stage in Shumiya Cataract Rats.

We designed an intravitreal injection formulation containing lanosterol nanoparticles (LAN-NPs) via the bead mill method and evaluated the therapeutic effect of LAN-NPs on lens structure collapse and opacification using two rat cataract models (SCR-N, rats with slight lens structure collapse; SCR-C, rats with the combination of a remarkable lens structure collapse and opacification). The particle size of lanosterol in the LAN-NPs was around 50–400 nm. A single injection of LAN-NPs (0.5%) supplied lanosterol into the lens for 48 h, and no irritation or muddiness was observed following repeated injections of LAN-NPs for 6 weeks (once every 2 days). Moreover, LAN-NPs repaired the slight collapse of the lens structure in SCR-N. Although the remarkable changes in the lens structure of SCR-C were not repaired by LAN-NP, the onset of opacification was delayed. In addition, the increase of cataract-related factors (Ca2+ contents, nitric oxide levels, lipid peroxidation and calpain activity levels) in the lenses of SCR-C was attenuated by the repeated injection of LAN-NPs. It is possible that a deficiency of lanosterol promotes the production of oxidative stress. In conclusion, it is difficult to improve serious structural collapse with posterior movement of the lens nucleus with a supplement of lanosterol via LAN-NPs. However, the intravitreal injection of LAN-NPs was found to repair the space and structural collapse in the early stages in the lenses.

Adaptation of nitrate reductase activity assay for high throughput screening of crops

The possibility of freeze drying of plant material and its grinding in a shaking bead mill to determine the activity of nitrate reductase (NR) was studied. The effectiveness of applying this approach to high throughput mass screening of crops was shown. The assay was carried out on seedlings of common wheat (Triticum aestivum) of the following cultivars: Altigo, Vassa, Grom, Doka, Soberbash, Starshina, Fisht and spring wheat Novosibirskaya 67. The crops were grown during 4-5 weeks on substrate without nitrogen and on substrate supplemented with 50 millimol / l (mM) of potassium nitrate. Nitrate reductase in plants retained its activity after lyophilization and grinding of dried leaves in a mill. The proposed protocol for NR activity assay is suitable for plant lysates with an NR activity suffi cient to form nitrite in the range of 5–120 micromoles / l (μM) in 800 μl of reaction mix (for instance, freeze-dried sample originated from 100 mg of wheat seedling leaves). Centrifugation of a plant lysate at 20,000 g almost did not change NR activity compared to 12,000 g that is achievable for most lab centrifuges. Lysates from fresh leaves contained signifi cantly more total protein than lysates from lyophilized leaves (with an equal amount of starting wet material). The difference in the nitrate-reducing activity in lysates from fresh and lyophilized leaves was not as high as the difference in protein concentration. Thus, the activity of NR calculated per g of total protein was higher in lyophilized leaves than in fresh leaves. The activity of NR was signifi cantly induced by nitrate for all cultivars. The basal and nitrate-induced NR activity varied widely between the cultivars, and the induction ranged from 2.5 fold for Novosibirskaya 67 variety and 2.7 fold for Vassa to 5.4 for Altigo and 5.7 fold for Grom.

Study of Top-down and Bottom-up Approaches by Using Design of Experiment (DoE) to Produce Meloxicam Nanocrystal Capsules.

In order to investigate the correlation among energy input-related, drug-related, and stabilizer-related aspects for both top-down and bottom-up nanocrystal production, meloxicam nanosuspensions (NS) were produced by using three different methods (low-energy wet milling, high-pressure homogenization, and precipitation) and each method was optimized by using design of experiment (DoE). Box-Behnken design of 3 factors and 3 levels was applied for the optimization of each method. All the three models were found to be significant and the optimized process parameters were used for production of NS, respectively. Interestingly, by comparison of the top-down and bottom-up approaches, the influence of energy input (homogenization pressure or milling speed) from the instruments seemed not significant for top-down compared with bottom-up for this drug. Different mechanisms of homogenization (relatively high energy zone) and milling (relatively low energy zone) led to obtained various significant correlations for each method. Capsules containing nanocrystals were successfully produced by using a novel method applying NS (after wet bead milling and homogenization processes) as wetting agent for direct capsuling and showed superiority regarding as dissolution rate compared with the traditional two-step method (freeze-dried powder used for capsuling as the first step). Different NS preparation methodologies proved to have a direct influence on the following capsuling process and consequently, in the dissolution rate. This study also proved that residual DMSO in nanosuspension after precipitation process could affect the freeze-drying process, which might further alter the redispersion and influence the downstream processes.

Reliable approaches to extract high-integrity RNA from skin and other pertinent tissues used in pain research.

Introduction:Comprehensive mRNA sequencing is a powerful tool for conducting unbiased, quantitative differential gene expression analysis. However, the reliability of these data is contingent on the extraction of high-quality RNA from samples. Preserving RNA integrity during extraction can be problematic, especially in tissues such as skin with dense, connective matrices and elevated ribonuclease expression. This is a major barrier to understanding the influences of altered gene expression in many preclinical pain models and clinical pain disorders where skin is the site of tissue injury.Objective:This study developed and evaluated extraction protocols for skin and other tissues to maximize recovery of high-integrity RNA needed for quantitative mRNA sequencing.Methods:Rodent and human tissue samples underwent one of the several different protocols that combined either RNA-stabilizing solution or snap-freezing with bead milling or cryosectioning. Indices of RNA integrity and purity were assessed for all samples.Results:Extraction of high-integrity RNA is highly dependent on the methods used. Bead-milling skin collected in RNA-stabilizing solution resulted in extensive RNA degradation. Snap-freezing in liquid nitrogen was required for skin and highly preferable for other tissues. Skin also required cryosectioning to achieve effective penetration of RNA-stabilizing solution to preserve RNA integrity, whereas bead milling could be used instead with other tissues. Each method was reproducible across multiple experimenters. Electrophoretic anomalies that skewed RNA integrity value assignment required manual correction and often resulted in score reduction.Conclusion:To achieve the potential of quantitative differential gene expression analysis requires verification of tissue-dependent extraction methods that yield high-integrity RNA.

Production of flavorful alcohols from woods and possible applications for wood brews and liquors.

This work explores the utilization of wood for high-value production of novel alcoholic brews and liquors with natural flavors. The process capitalizes on our original wet-type bead milling (WBM) technology that enables direct enzymatic saccharification and alcohol fermentation of wood without chemical and heat treatment, resulting in the absence of toxic compounds. When alcohol-based products from various wood species, including Cryptomeria japonica (cedar), Cerasus × yedoensis (cherry), and Betula platyphylla (birch), were analyzed by SPME-GC-MS, different natural flavor components were found in each. Correlation analysis using Heracles NEO and ASTREE V5 showed that the alcohols from wood have different flavor and taste characteristics when compared with those of existing commercial liquors. From pilot-scale experiments, the yield of alcoholic brew per biomass amount was determined. Pilot-scale runs established the importance of optimum wood particle size during WBM for efficient alcohol production. Although the alcohol produced from wood must first be established as safe for human consumption, this is the first description of drinking alcohols produced from wood. This work may open up important avenues for the exploitation of wood resources toward food production to further advance the current state of forestry.

Green Synthesis of Silver Nanoparticles by Low-Energy Wet Bead Milling of Metal Spheres.

A low-energy, magnetically-driven milling technique for the synthesis of silver nanoparticles is proposed, where the grinding medium and the metal precursor consisting of silver spheres have the same shape and size, belonging to a millimetric scale. The process is carried out at room temperature in aqueous solvent, where different types of capping agents have been dissolved to damp particle agglomeration. The particle diameters, determined by dynamic light scattering and transmission electron microscopy, have been compared with those typical of conventional wet-chemical bottom-up synthesis processes. The use of milling spheres and metal precursor of the same initial shape and size allows to overcome some drawbacks and limitations distinctive of conventional bead-milling equipment, generally requiring complex operations of separation and recovery of milling media. The milling bead/nanoparticle diameter ratio obtained by this approach is higher than that typical of most previous wet bead milling techniques. The method described here represents a simple, one-pot, cost-effective, and eco-friendly process for the synthesis of metal nanoparticles starting from a bulky solid.

Combined simultaneous enzymatic saccharification and comminution (SESC) and anaerobic digestion for sustainable biomethane generation from wood lignocellulose and the biochemical characterization of residual sludge solid

Simultaneous enzymatic saccharification and comminution (SESC) was used for large-scale anaerobic digestion of wood lignocellulose to generate methane and unmodified lignin. During SESC, 10% aqueous mixture of powdered debarked wood from various species was subjected to bead milling with hydrolytic enzymes to generate particles below 1 μm. This slurry was directly used as a cosubstrate for anaerobic digestion in a 500 L stirred-tank reactor. Temperature and hydraulic retention time (HRT) were maintained at 50 °C and 30 days, respectively. At stable operation periods, an average yield of 224 L of methane per kg of cedar was attained. Comparable yields were achieved with red pine, elm, oak, and cedar bark. High-throughput microbial analysis established the presence of a relevant community to support the elevated level of methane production. The stability of the unmodified lignin in anaerobic digestion was also confirmed, allowing for its recovery as an important by-product.

Combination of cell disruption technologies for lipid recovery from dry and wet biomass of Yarrowia lipolytica and using green solvents

This work aims to investigate the efficiency of bead milling combined or not with high-pressure homogenization on the cell disruption and lipid recovery from Yarrowia lipolytica oleaginous yeast. First, a simulation study involving the use of the Hansen solubility parameters’ approach was performed in order to identify, among 41 conventional and “green” solvents, the most promising ones that are able to replace n-hexane for lipid recovery from Y. lipolytica biomass. The results obtained showed that the pre-treatment involving both high-pressure homogenization and bead milling applied sequentially was more performant than that involving bead milling alone. In addition, bead-milling parameters were optimized showing an optimal bead size of 4.9 mm and a processing time of 30 s. Among the tested solvents, isoamyl acetate was selected as the most appropriate “green” solvent, maximizing the lipid extraction, compared to n-hexane. Despite the better performance of the dry route compared to the wet one, promising results were obtained towards 1) minimizing the energy consumed and 2) replacing n-hexane by “green” solvents for lipid recovery from Y. lipolytica yeast.

Use mechanochemical activation to enhance interfacial contaminant removal: A review of recent developments and mainstream techniques.

Interfacial processes, including adsorption and catalysis, play crucial roles in environmental contaminant removal. Mechanochemical activation (MCA) emerges as a competitive method to improve the performance of adsorbents and catalysts. The development and application of MCA in the last decades are thereby systematically reviewed, particularly highlighting its contribution to interfacial process modulation. Two typical apparatuses for MCA are ball milling (BaM) and bead milling (BeM). Compared to BaM, BeM is able to yield a much higher MCA intensity, because it could pulverize bulk solid particles to nearly 100 nm. Since MCA intensity on the adsorbents and catalysts is directly responsible for the contaminant removal afterwards, quantitative and qualitative determination methods for valid MCA intensity are introduced. MCA benefits both the adsorption kinetics and capacity of powdered activated carbon by increasing the specific surface area. Carbon oxidation should be given an additional attention, but potentially favors the adsorption of heavy metals. MCA favors the catalyst performance by providing abundant surface functional group and increasing the free energy in the near-surface region. Finally, the future research needs are identified.

Influence of submicro-sheet zinc phosphate modified by urea-formaldehyde on the corrosion protection of epoxy coating

Submicron-sheet zinc phosphate (SZP) modified with urea-formaldehyde, called as UFSZP pigment, were synthetized to improve the compatibility of pigment/resins interface. Then the coatings with SZP and UFSZP pigments were prepared by planetary ball milling or bead milling. Finally, the corrosion protections of coatings were studied through electrochemical impedance spectroscopy, adhesion test and morphological analysis. The dispersions of pigments in coatings indicated that urea-formaldehyde modification could effectively reduce the pigment clustering and diminish particle size, while using planetary ball milling. Consequentially, the PM-UFSZP coating with excellent dispersion state of pigments displayed the excellent protection performance. This showed that UF modification on the pigments without active spot would be a significant technology to reduce the pigment size and to improve the dispersion of pigments in coatings, while using the planetary ball milling.

Correlations between quality parameters of some types of unpasteurized beer and consumers safety

Most microalgae cells are very resistant to mechanical and chemical stresses. Because target products are mainly located inside the cells, disruption of the cell wall is an essential step in downstream processing to recover the microalgae ingredients. This study is focused on the development of a mild cell disruption method based on explosive CO2 decompression to allow the recovery of multiple sensitive products.The principle behind cell rupture via explosive decompression is the uptake of a gas under elevated pressure into the microalgae cells, where after a sudden depressurization gas expansion causes rupture of the cells. Conventional explosive decompression uses stirred tank reactors wherein, because of inefficient mixing, the gas/liquid interfacial area is minimal, resulting in long contact times, inefficient gas uptake and inefficient cell rupture. To increase the mixing yield and the formation of a gas-liquid micro-emulsion, a new continuous apparatus and a method were developed to process microalgae biomass by CO2 based explosive decompression. The final design consisted of 2 pumps, a tubing system, a sparger, a hydrodynamic agitation zone and a heated relief valve. Experimental comparison of the conventional batch and the new continuous devices showed that process time was reduced 3.2–9.6 fold, the biomass and biochemical release efficiency increased more than 2 fold, and CO2 consumption reduced 2–4 fold. The method can be considered as mild, since it can operate at room temperature without addition of chemicals. Moreover, the calculated shear rate on the algae cells is only 0.33% of the shear rate recorded during bead milling, while depending on the process parameters releasing a similar amount of biomass components from the cells into the supernatant. The article describes the development of the explosive decompression systems supported by computational fluid dynamics simulations and experimental data on algae cell disruption, complemented with a first techno-economic assessment.

Solid Nanocrystals of Rebamipide Promote Recovery from Indomethacin-Induced Gastrointestinal Bleeding.

Indomethacin (IMC)-induced gastrointestinal (GI) injuries are more common in rheumatoid arthritis (RA) patients than in other IMC users, and the overexpression of nitric oxide (NO) via inducible NO synthase (iNOS) is related to the seriousness of IMC-induced GI injuries. However, sufficient strategies to prevent IMC-induced GI injuries have not yet been established. In this study, we designed dispersions of rebamipide (RBM) solid nanocrystals (particle size: 30–190 nm) by a bead mill method (RBM-NDs), and investigated whether the oral administration of RBM-NDs is useful to prevent IMC-induced GI injuries. The RBM nanocrystals were spherical and had a solubility 4.71-fold greater than dispersions of traditional RBM powder (RBM-TDs). In addition, the RBM-NDs were stable for 1 month after preparation. The RBM contents in the stomach, jejunum, and ileum of rats orally administered RBM-NDs were significantly higher than in rats administered RBM-TDs. Moreover, the oral administration of RBM-NDs decreased the NO levels via iNOS and area of the GI lesions in IMC-stimulated RA (adjuvant-induced arthritis rat) rats in comparison with the oral administration of RBM-TDs. Thus, we show that the oral administration of RBM-NDs provides a high drug supply to the GI mucosa, resulting in a therapeutic effect on IMC-induced GI injuries. Solid nanocrystalline RBM preparations may offer effective therapy for RA patients.

Investigation of Citrate Modified Layered Double Hydroxides by Bead Milling Technique

Agglomeration and low stability of layered double hydroxides (LDHs) suspended in water significantly affects its properties for water base applications. In this study, the stability of LDHs suspended in water was improved by using bead milling for size reduction and by surface treatment with tri-sodium citrate. The result showed that bead milling technique can reduce the agglomeration and induce the adsorption of tri-sodium citrate on LDHs without intercalation. Following redispersion in water, the stability of citrate-modified LDHs was >1 hr with particle size around 177 nm, whereas the particle size of unmodified LDHs was around 40 μm with fast sedimentation.

Optimization of dispersed LaPO4:Tb nanosol and their photoluminescence properties

LaPO4:Tb nanophosphor with different concentrations of Tb3+ 0.05–0.15 mol % has been synthesized via sol-gel process. The synthesized nanophosphor was dried under 80 °C for 24 hrs. Dependent on the different concentration of Tb3+, the optimum concentration for the enhanced luminescence intensity was determined to be 0.15 mol %. The high luminescent nanophosphor with Tb3+ = 0.15 mol % was heat treated at 200–800 °C for 4 hrs. The nanophosphor heat-treated at 600–800 °C showed high photoluminescence (PL) property by monitoring at 254 nm excitation wavelength. The nanophosphor heat-treated at 200–400 °C is well crystalline in the hexagonal phase, but the crystal phase nature is shifted to monoclinic in case of the sample that heat treated above 400 °C. On the basis of weakly agglomerated nanoparticles, the nanophosphor was dispersed and converted into nanosol under controlled bead mill wet process. Based on particle size analyzer (PSA) the obtained nanosol median particle size (D50) was below 200 nm. Finally, the low PL properties of LaPO4:Tb nanosol with their characteristics green color emission was recovered after calcination at 650 °C under N2 atmosphere for 2 hrs. The crystallinity, morphology and particle size of the nanophosphors were investigated using X-ray diffraction (XRD), FE-SEM, and PSA. The nanosol with green color emission prepared in this work potentially meets their applications for security coatings.

Promising Dissociation Technologies for Preparation of Minerals to Flotation

Milling of minerals and middlings is studied in ultra-fine bead mills, Vertimill fine milling machines and in hydropercussion-and-cavitation machines (rotary-pulsating type). Fine and ultra-fine milling provides the wanted rate of dissociation of sulphide minerals and host rocks as compared with ball milling, while hydropercussion-and-cavitation milling improves selectivity of dissociation at equal grain size composition of products from the rotary-pulsating machines and ball mills. Possible improvement of ore quality by fine hydraulic vibratory screening before deep concentration is examined. It is shown that as against hydrocyclones in pre-treatment circuits, fine hydraulic vibratory screens reduce circulation of fines with oversize flow, decrease overgrinding and increase mass fraction of optimal sizes for subsequent flotation.

Combination with l-Menthol Enhances Transdermal Penetration of Indomethacin Solid Nanoparticles.

This study designed the transdermal formulations containing indomethacin (IMC)—1% IMC was crushed with 0.5% methylcellulose and 5% 2-hydroxypropyl-β-cyclodextrin by the bead mill method, and the milled IMC was gelled with or without 2% l-menthol (a permeation enhancer) by Carbopol® 934 (without menthol, N-IMC gel; with menthol, N-IMC/MT gel). In addition, the drug release, skin penetration and percutaneous absorption of the N-IMC/MT gel were investigated. The particle sizes of N-IMC gel were approximately 50–200 nm, and the combination with l-menthol did not affect the particle characterization of the transdermal formulations. In an in vitro experiment using a Franz diffusion cell, the skin penetration in N-IMC/MT gel was enhanced than the N-IMC gel, and the percutaneous absorption (AUC) from the N-IMC/MT gel was 2-fold higher than the N-IMC gel. On the other hand, the skin penetration from the N-IMC/MT gel was remarkably attenuated at a 4 °C condition, a temperature that inhibits all energy-dependent endocytosis. In conclusion, this study designed transdermal formulations containing IMC solid nanoparticles and l-menthol, and found that the combination with l-menthol enhanced the skin penetration of the IMC solid nanoparticles. In addition, the energy-dependency of the skin penetration of IMC solid nanoparticles was demonstrated. These findings suggest the utility of a transdermal drug delivery system to provide the easy application of solid nanoparticles (SNPs).

Evaluation of disruption/permeabilization methodologies for Microcystis aeruginosa as alternatives to obtain high yields of microcystin release

The extraction of the wide range of useful bioactive compounds produced by cyanobacteria is still a major bottleneck at industrial scale. In addition to the high costs, extraction efficiencies are also commonly low, with low cell disruption efficiencies playing a particularly significant role in intracellular compounds' release. To increase the chances of an extended use of the cyanobacteria toxin microcystin in several biotechnological fields, we aimed to optimize five different disruption techniques: bead milling, microwave, freeze-thaw cycles, high-speed homogenization, and sonication. For each of the methods tested, the conditions that maximized the intracellular organic matter release were: i) 20% of beads and treatment time of 7 min (bead milling); ii) 800 W for 1.5 min (microwave); iii) three 12-h freeze-thaw cycles at −20 °C; iv) 15,000 rpm for 7 min (high-speed homogenization); and v) 40 kHz for 10 min (sonication).Sonication and freeze-thaw cycles followed by sonication revealed to be the most effective methodologies to ensure a maximum intracellular organic matter release and, consequently, microcystin availability for being extracted. The decrease of cells' viability was however more evident in freeze-thaw cycles, freeze-thaw cycles followed by sonication, and microwave where only 0.3, 0.05 and 0.9% of the initial cells, respectively, maintained their viability after being treated. On the other hand, sonication and bead milling reduced the viability of the original culture to 5 and 15.5%, respectively, while high-speed homogenization did not show any significant differences compared to control.According to the results obtained in this study, the most suitable methodology to maximize the release of microcystin was therefore the use of sonication (40 kHz) during 10 min.

Effectiveness of micronizing zinc borate to improve its fungicidal properties

The effectiveness was evaluated for an established wood preservative, zinc borate, prepared in an agitating bead mill to extensively reduce its particle size. The generated micro- or nano-particles of zinc borate were characterized by X-ray powder diffraction, and the particle size distribution was determined to evaluate the effect of milling. Then the fungicidal effectiveness of the zinc borate of both milled and unmilled samples were assayed against brown- and white-rot fungi, on culture medium and on conifer and hardwood as substrates. Treated wood samples were subjected to leaching tests. Scanning electron microscopic images of wood samples were examined to analyze the distribution of zinc borate within the wood. The micronized zinc product kept its crystal structure intact, and it increased the proportion of particles with diameters below 100 nm by 25% when compared to the unmilled product. Malt extract-agar medium supplemented with 2.5% of w/w milled and unmilled zinc borate inhibited fungal growth tested. Both milled and unmilled zinc borate protected the wood when not subjected to leaching. The milled sample of zinc borate improved resistance to leaching, which would allow its application in environments of high moisture content; however, it did not improve the fungicidal action against decay fungi.

Simultaneous epoxy grafting on SiO2 nanoparticles during bead milling and their effects on the mechanical properties of epoxy-based composites

Epoxy resin-grafted SiO2 nanoparticles stabilized in toluene were successfully designed by the simultaneous surface modification of SiO2 nanoparticles during bead milling which involves the adsorption of polyethyleneimine-oleic acid complex (PEI-OA) and epoxy resin grafting to the free amine groups of PEI-OA (PEI-OA-Epoxy). The effectiveness of epoxy grafting on the properties of the SiO2/epoxy based nanocomposites were investigated using a bead-milled SiO2/toluene suspension stabilized with PEI-OA, PEI-OA-Epoxy, and a complex of PEI and an anionic surfactant comprising an epoxy-soluble polyethylene glycol-based chain (PEI-AS). While SiO2 nanoparticles were pulverized with similar sizes (c.a. 126–171 nm) and stabilized in toluene with any of the three surface modifications, PEI-OA-stabilized SiO2 nanoparticles aggregated during processing epoxy-based composites. PEI-AS- and PEI-OA-Epoxy-stabilized SiO2 nanoparticles maintained their dispersion stability, however, the epoxy composites with PEI-OA-Epoxy-stabilized SiO2 nanoparticles exhibited better material properties, such as increase in the strain at fracture and higher Tg.