An experimental investigation of the stability of ethylcellulose latex

Influence mechanisms of linoleic acid and oleic acid on the gel properties of egg yolk protein

BACKGROUND

Gel property is among the crucial functional properties of egg yolk (EY), which determines the texture and flavor of EY products. In the present study, the effects of two unsaturated fatty acids [monounsaturated fatty acid oleic acid (OA) and diunsaturated fatty acid linoleic acid (LA)] on the gel properties of EY protein were investigated.

RESULTS

Compared with the blank group, the addition of LA and OA (10-50 g kg-1) improved the gel hardness (from 270.54 g to 385.85 g and 414.38 g, respectively) and viscosity coefficient (from 0.015 Pa.sn to 11.892 Pa.sn and 1.812 Pa.sn, respectively). The surface hydrophobicity of EY protein increased to a maximum value of 40 g kg-1 with the addition of both fatty acids (39.06 μg and 41.58 μg, respectively). However, excess unsaturated fatty acids (≥ 50 g kg-1) disrupted the completeness of the gel matrix and weakened the structural properties of the EY gel.

CONCLUSION

Both fatty acids improved the gel properties of EY protein. At the same addition level, OA was superior to LA in improving gel properties. The present study provides a theoretical underpinning for the sensible application of unsaturated fatty acids in improving EY gel properties. © 2024 Society of Chemical Industry.

A Rapid 3-Day Excipient Screening Methodology and its Application in Identifying Chemical Stabilizers for Solid Formulations with Mixed Mechanisms of Degradation

This study outlines a practical approach for assessing chemical instability by heating the drug-excipient binary mixtures or multi-excipient formulations at 75°C for 3 days before characterization. Differentiating itself from other excipient compatibility methods, our methodology necessitates a saturated aqueous slurry rather than arbitrarily fixed water content. This allows bulk and surface water in the excipient to contribute to drug degradation. The synergistic impact of surface water and elevated temperature expedites degradation kinetics, resulting in accelerated data generation. Among excipient compatibility methods available, our method is quantitative and merges with traditionally used methodologies. The devised nomograph enables extrapolation of shelf life at 20°C from experimental data obtained at 75°C. This methodology also helped identify stabilizers for the drug NVS-1 where traditional excipient compatibility programs had failed. Incorporation of monovalent salts, such as sodium/potassium chloride and sodium bicarbonate at 5% w/w, significantly enhanced the chemical stability of NVS-1, ensuring stable tablet formulations. Our hypothesis posits that stabilization is due to increased ionic strength in the slurry, which stabilizes an induced dipole within the polar NVS-1 drug. Additionally, the presence of ions in the moisture layer is anticipated to stabilize π-π stacking of two planar aromatic NVS-1 molecules. The expedited generation of experimental data allowed the identification of inorganic salts to supplement a standard excipient compatibility screening panel. Considering the economic implications of stability testing methodologies in effort, cost, and duration, a faster turnaround in chemical stability data enhances formulation selection. This ultimately facilitates the development of drug formulations with greater efficiency without delays.

Quantitative proteomic analysis of chicken egg white and its components

The protein profiles and properties of chicken egg white and its three components (thick egg white, TKEW; thin egg white, TNEW; and chalaza, CLZ) were comprehensively compared. The proteomes of TNEW and TKEW are relatively similar, but the abundance of mucin-5B and mucin-6 (the two subunits of ovomucin) is significantly higher in TKEW than in TNEW (42.97% and 870.04%, respectively), while the lysozymes in TKEW are 32.57% higher (p < 0.05) than those in TNEW. Meanwhile, the properties (including the spectroscopy, viscosity, and turbidity) of TKEW and TNEW are significantly different. Comprehensively, it is speculated that the electrostatic interactions between lysozyme and ovomucin are the main reason for the high viscosity and turbidity of TKEW. Compared with egg white sample (EW), CLZ has a higher abundance of insoluble proteins (mucin-5B, 4.23-fold; mucin-6, 6.89-fold) and a lower abundance of soluble proteins (ovalbumin-related protein X, 89.35% lower than EW; ovalbumin-related protein Y, 78.51% lower; ovoinhibitor, 62.08% lower; riboflavin-binding protein, 93.67% lower). These compositional differences should explain the insolubility of CLZ. These findings are important references for deepening the research and development of egg white in the future, such as the thinning of egg white, the molecular basis of changes in egg white properties, and the differential application of TKEW and TNEW.

Hydrothermal Co-Crystallization of Novel Copper Tungstate-Strontium Titanate Crystal Composite for Enhanced Photocatalytic Activity and Increased Electron–Hole Recombination Time

The development of catalysts continues to have a significant influence on science today since we can utilize them to efficiently destroy some contaminants. A study in this field is justified because there is a dearth of comprehensive literature on the creation of SrTiO3-based photocatalysts. Related to this topic, here we report the facile preparation of a structure-modified SrTiO3 photocatalyst, by incorporating CuWO4. Within the case of the CuWO4-modified samples (0.5–3 wt% nominal CuWO4 content), the photo-oxidation of phenol, as a contaminant, was more than two times higher than the initial SrTiO3. However, the photocatalytic activity does not change linearly with increasing CuWO4 content, and the CWS2.5 (2.5 wt% nominal CuWO4 content and 4.25 wt% measured content) has the highest photo-activity under the applied conditions. The reason for the better activity was the increased recombination time of charge separation on the catalyst surface. Slower recombination can result in more water being oxidized to hydroxyl radicals, leading to the faster decomposition of the phenol.

Development and Preliminary Characterization of Polyester-Urethane Microparticles Used in Curcumin Drug Delivery System for Oropharyngeal Cancer

Background and Objectives: Curcumin (Cc) as an active substance is known for its anti-inflammatory, anticoagulant, antioxidant, and anti-carcinogenic effects, together with its role in cholesterol regulation, and its use in different gastrointestinal derangements. On the other hand, curcumin can be used for its properties as an inactive substance, with Cc particles being more often tested in pharmaceutical formulations for drug delivery, with promising safety records and kinetics. The aim of this research was to obtain and characterize polyurethane microparticles that can be used as a carrier with a controlled Cc release. Materials and Methods: The in vitro samples were characterized by the Zetasizer procedure, and UV-Vis spectroscopy, while the in-vivo measurements on human subjects were performed by non-invasive skin assays (trans-epidermal water loss, erythema, and skin hydration). A total of 16 patients with oropharyngeal cancer stages II and III in equal proportions were recruited for participation. Results: The experimental values of sample characteristics using the Zetasizer identified a mean structural size of 215 nm in the polyester-urethane preparate (PU), compared to 271 nm in the curcumin-based PU. Although the size was statistically significantly different, the IPDI and Zeta potential did not differ significantly (22.91 mV vs. 23.74 mV). The average age during the study period was 57.6 years for patients in the PU group, respectively, and 55.1 years in those who received the curcumin preparations. The majority of oropharyngeal cancers were of HPV-related etiology. There were no significant side effects; 75.0% of patients in the PU group reporting no side effects, compared to 87.5% in the Cc group. The 48 h TEWL measurement at the end of the experiment found a statistically significant difference between the PU and the Cc group (2.2 g/h/m² vs. 2.6 g/h/m²). The erythema assessment showed a starting measurement point for both research groups with a 5.1-unit difference. After 48 h, the difference between PU and PU_Cc was just 1.7 units (p-value = 0.576). The overall difference compared to the reference group with sodium lauryl sulfate (SLS) was statistically significant at a 95% significance level. Conclusions: Our findings indicate the obtaining of almost homogeneous particles with a medium tendency to form agglomerations, with a good capacity of encapsulation (around 60%), a medium release rate, and a non-irritative potential. Therefore, this polyester-urethane with Cc microparticles can be tested in other clinical evaluations.

Optimization of Plasmonic Copper Content at Copper-Modified Strontium Titanate (Cu-SrTiO3): Synthesis, Characterization, Photocatalytic Activity

Catalyst development still has a major impact on science today, as we can use catalysts to break down certain pollutants in an energy-efficient way. There is no comprehensive literature on the development of SrTiO3-based photocatalysts, so study in this area is justified. Related to this topic, here we report the facile preparation of surface-modified SrTiO3 photocatalyst, performed by plasmonic copper deposition. In the case of the copper-modified samples (0.25–3 wt.% Cu content), the photooxidation of phenol, as model contaminant, was almost 4–5 times higher than the bare SrTiO3. However, the photocatalytic activity was not linearly related to copper content, since the highest photoactivity was achieved at 1 wt.% copper content. The reason for the better activity was the plasmonic effect of copper, which increases the recombination time of charge separation on the catalyst surface. During slower recombination, more water is oxidized to hydroxyl radicals, which can lead to faster degradation of phenol.

Effect of ball milling-assisted glycosylation modification on the structure and foaming property of egg white protein

The effect of different glycosylation degrees on molecular structure and foaming property of egg white protein (EWP) was investigated using ball milling-assisted glycosylation. The results showed the foaming ability (FA) and foam stability (FS) of EWP improved when the degree of glycosylation was increased. In particular, FA of ball milling-assisted glycosylation of EWP enhanced by 39.9% and 28.8%, and the FS increased by 28.7% and 24.0% compared with EWP and ball milling egg white protein (BE) at 150 min of reaction. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis could reflect the grafting degree of EWP and glucose molecules from the side. When EWP was fully grafted with glucose, endogenous fluorescence and free sulfhydryl groups indicated that tertiary structure of EWP was depolymerized, and Fourier transform infrared spectroscopy showed the secondary structure tended to change from order to disorder. The results of this study indicated that ball milling-assisted glycosylation modification was a practical method to improve the foaming property of EWP. PRACTICAL APPLICATION: EWP has great FA and FS, making it indispensable in the baking industry. In this study, ball milling-assisted glycosylation was used to improve the foaming property of EWP, and the molecular structure of EWP with different degrees of glycosylation was fully resolved. The results demonstrated that ball milling, as a physical pretreatment, can fully unfold the structure of EWP. When sugar molecules were fully grafted, the particle size of EWP reduced, solubility increased, and the stability of system improved, thus enhancing the foaming property of EWP. The results can provide theoretical basis for improving the foaming property of EWP and provide a reference value for its industrial application.

Mechanism of differences in characteristics of thick/thin egg whites during storage: Physicochemical, functional and molecular structure characteristics analysis

This study systematically analyzed and compared thechanges of physicochemical, functional and molecular structural characteristics between thick egg white (KEW) and thin egg white (NEW) during storage. Analysis of physicochemical properties showed that moisture content decreased significantly with the increase of pH during storage. KEW was gradually thinning, while NEW was closer to Newtonian fluid. Functional properties indicated that KEW thermal gel was gradually hard and brittle with the properties of NEW. KEW had better emulsifying property than NEW, and NEW had superior foaming ability. The α-helix and β-sheet in the FT-IR spectrum showed a downward trend, revealing secondary structure changed from order to disorder. Enhancement of fluorescence intensity indicated the structural unfolding and exposure of tryptophan residues. SDS-PAGE proved that OVO might be related to the difference between KEW and NEW characteristics. This study provided new idea and reference value for egg storage and diversified utilization of egg white.

Nanodispersions of Polyelectrolytes Based on Humic Substances: Isolation, Physico-Chemical Characterization and Evaluation of Biological Activity

Natural polyelectrolytes, including in the form of complexes with colloidal particles, are increasingly used in pharmacy due to the possibility of regulated attachment of medicinal substances and their targeted delivery to the target organ. However, the formation, stability, and molecular-mass characteristics of polyelectrolyte nanodispersions (ND) vary depending on the nature and composition of the medium of their origin. This is due to the lack of standardized approaches to quality control and regulatory documentation for most natural ND. In this paper, we first introduced the isolation, followed by investigations into their physico-chemical properties and bioactivity. Using the dried droplet method, we were able to detect the “coffee ring effect”. Fractographic studies of the surface structure of EHA and FA dried samples using SEM showed its heterogeneity and the presence of submicron particles encapsulated in the internal molecular cavities of polyelectrolyte. FTIR spectroscopy revealed the ND chemical structure of benzo-α-pyron and benzo-γ-pyron, consisting of nanoparticles and a branched frame part. The main elements detected by X-ray fluorescence in humic substance extract and fulvic acid include Si, P, S, K, Ca, Mn, Fe, Cu, Zn, whereas Fe is in high concentrations. The UV-spectra and fluorescent radiation demonstrated the possibility of studying the effect of the fulvate chromone structure on its optical properties. It is shown that dilution of the initial solutions of polyelectrolytes 1:10 contributes to the detection of smaller nanoparticles and an increase in the absolute value of the negative ζ-potential as a factor of ND stability. A study of the EHS effect on the SARS-CoV-2 virus infectious titer in the Vero E6 cell showed the effective against virus both in the virucidal scheme (the SI is 11.90–22.43) and treatment/prevention scheme (the SI is 34.85–57.33). We assume that polyelectrolyte ND prevent the binding of the coronavirus spike glycoprotein to the receptor. Taking into account the results obtained, we expect that the developed approach can become unified for the standardization of the ND natural polyelectrolytes complex, which has great prospects for use in pharmacy and medicine as a drug with antiviral activity.

The Effects of Primary Unconjugated Bile Acids on Nanoencapsulated Pharmaceutical Formulation of Hydrophilic Drugs: Pharmacological Implications

Introduction

In a recent study, in our laboratory, primary unconjugated bile acids, commonly found in humans, chenodeoxycholic acid (CDCA), have been shown to improve stability of nanoencapsulated lipophilic drugs and improve their release profile after oral administration likely via electrokinetic stabilisation. Hence, this study aimed to examine the effects of CDCA on exerting similar effects on hydrophilic drugs.

Methods

Various CDCA-based formulations were produced for the orally administered hydrophilic drug, metformin. Analyses of these formulations included electrokinetic potentials, topography, drug and CDCA formulation contents, nano size distribution, heat-induced deformation and outer-core expansion indices, release profiles, shell-resistance ratio, and thermal and chemical indices. With the drug’s main target being pancreatic beta-cells, the formulations’ effects on cell viability, functions and inflammatory profiles were also investigated.

Results and Conclusions

CDCA-based metformin formulations exhibited improved stability and release profiles via thermal, chemical and electrokinetic effects, which were formulation-dependent suggesting potential applications of CDCA in the oral targeted delivery of hydrophilic drugs.

Cellular gene delivery via poly(hexamethylene biguanide)/pDNA self-assembled nanoparticles

Cellular gene delivery via polycations has wide implications for the potential of gene therapy, but it has remained a challenge due to the plethora of pre- and post-uptake barriers that must be overcome to reach desired efficiency. Herein we report poly(hexamethylene biguanide) (PHMB) as a nano-vector for intracellular delivery of plasmid DNA (pDNA) and oligodeoxynucleotides (ODNs). PHMB and pDNA or ODNs self-assembled into complex nanoparticles at different pH values (7.4 and 12). Their size, charge, cellular uptake, and gene-expression efficiency are assessed and compared to PEI analogues. The systematic results show that the nanoparticles are effective in delivering plasmid DNA and ODNs to model cell lines in culture (HepG2, HEK293T, HeLa), with measurable changes in gene expression levels, comparable to and, in some conditions, even higher than PEI. The well-accepted safety profile of PHMB makes it a valuable candidate for consideration as an effective intracellular DNA vector for further study and potential clinical translation.

Synthesis of cross-linked poly(acrylic acid) nanogels in an aqueous environment using precipitation polymerization: unusually high volume change

For the first time, by using precipitation polymerization in an aqueous solution, a cross-linked poly(acrylic acid)-(pAA) nanogel was synthesized. pAA was synthesized and cross-linked with N,N'-methylenebisacrylamide (BIS) at 70°C in an acidified environment (pH 2) and containing 0.7 M NaCl using potassium persulfate as the initiator. Ionized pAA was soluble in water. The use of sodium chloride at low pH caused a decrease in the solubility of pAA and led to its precipitation and formation of cross-linked pAA nanogel. By using electron microscopies and light scattering techniques, the morphology, pH sensitivity and zeta potential of the obtained p(AA-BIS) nanogel were evaluated. The polymerization in an aqueous environment resulted in a very big swelling/shrinking coefficient (of approx. 4000) in response to pH and exhibited an unusually high negative zeta potential (of approx. -130 mV). These properties make the nanogel a very interesting sorbent and a construction material.

Poly(sodium 4-styrenesulfonate) Assisted Room-Temperature Synthesis for the Mass Production of Bismuth Oxychloride Ultrathin Nanoplates with Enhanced Photocatalytic Activity

Bismuth oxychloride ultrathin nanoplates (BiOCl-UTNs) are highly active, but their preparation are limited to closed-vessel hydrothermal and solvothermal techniques at high temperatures (110-180 °C). Here we report a straightforward poly(sodium 4-styrenesulfonate) (PSS)-mediated route for the large-scale synthesis of BiOCl-UTNs at room-temperature. In an open vessel, 6.15 g of BiOCl-UTNs with 3-5 nm thickness, and planar dimensions of 30-50 nm were produced. The strong electrostatic interaction between PSS and [Bi₂ O₂ ]²⁺ layers inhibited the growth rate of BiOCl nanoplates along <001> direction, and Na⁺ ions governed the electrolyte sedimentation to produce BiOCl-UTNs. The resulting BiOCl-UTNs exhibited high photocatalytic activity for the degradation of antibiotics and organic dyes because of their large specific surface area, increased light absorption ability, and fast separation and transfer efficiency of the photoexcited charge carriers.

An Industrial Scale Synthesis of Adipicdihydrazide (ADH)/Polyacrylate Hybrid with Excellent Formaldehyde Degradation Performance

A simple and versatile route for industrial scale synthesis of adipicdihydrazide (ADH)/polymer hybrids with excellent performance of formaldehyde degradation is proposed in this paper. The ADH compound is uniformly dispersed in poly(methyl methacrylate-butyl acrylate-methacrylic acid) (P(MMA-BA-MAA)) latex, which is validated by UV and dispersibility tests. The results illustrate that ADH has excellent compatibility and dispersion stability without affecting the film formation of the polymer latex. Furthermore, scanning electron microscope (SEM) and mapping analysis of the hybrid films also demonstrate that ADH is homogenously dispersed in the polymer matrix. Compared with neat polymers, the thermal properties of hybrid films are improved, for example, T_0.5 increases by 8.3 °C. According to qualitative tests of the 4-amino-3-hydrazino-5-mercapto-1,2,4-triazol-red/green/blue (AHMT-RGB) method, the hybrid films demonstrate high formaldehyde removal efficiency. On the basis of the semi-quantitative test of Fourier Transform infrared spectroscopy (FTIR) measurements, the rate of formaldehyde degradation can reach 1.034 × 10² mol/(h·m³) for the hybrid film with 5 wt% ADH.

Sulfonated Nanobamboo Fiber-Reinforced Quaternary Ammonia Poly(ether ether ketone) Membranes for Alkaline Polymer Electrolyte Fuel Cells

Alkaline polymer electrolyte fuel cells (APEFCs) are a new class of electrochemical devices that intrinsically enable the use of nonprecious metal catalysts. As an important component of APEFCs, alkaline polymer electrolytes (APEs) have been a research focus in recent decades. To minimize the ohmic loss and to facilitate the water transport, the APE membrane should be as thin as possible, which generally requires a trade-off between the ionic conductivity and the mechanical robustness/dimensional stability of the membrane. Here, we report a new reinforced APE membrane that can effectively disentangle such a trade-off. The quaternary ammonia poly(ether ether ketone) (QAPEEK) membrane is highly conductive but suffers from the overuptake of water, which leads to significant membrane swelling and weak mechanical strength. Upon reinforcing with sulfonated nanobamboo fiber (s-NBF), the swelling degree decreases from 27.5 to 7.5% in 80 °C water. The thickness of such an s-NBF/QAPEEK membrane can then be reduced to 15 μm, which diminishes the electrical resistance, very suitable for APEFC applications.

Influence of Biotechnological Processes, Speed of Formulation Flow and Cellular Concurrent Stream-Integration on Insulin Production from β-cells as a Result of Co-Encapsulation with a Highly Lipophilic Bile Acid

Introduction

We have shown that incorporation of the hydrophilic bile acid, ursodeoxycholic acid, into β-cell microcapsules exerted positive effects on microcapsules' morphology and size, but these effects were excipient and method dependent. Cell viability remained low which suggests low octane-water solubility and formation of highly hydrophilic dispersion, which resulted in low lipophilicity dispersion and compromised cellular permeation of the incorporated bile acid. Thus, this study aimed at investigating various microencapsulating methodologies using highly lipophilic bile acid (LPBA), in order to optimise viability and functions of microencapsulated β-cells.

Methods

Four different types of microcapsules were produced with (test) and without (control) LPBA, totalling eight different microcapsules. Microencapsulating methodologies were screened for best microcapsule-cell functions and microencapsulating processes were examined in terms of frequency, formulation flow, total bath-gelation time and cellular concurrent stream-integration rate, cell-viability, insulin production and inflammatory profile.

Results

Optimum biotechnological processes include formation frequency (Hz) of 2350, formulation flow (ml/min) of 1.2, total gelation time (min) of 18 and cellular concurrent stream-integration rate (ml/min) of 0.7. In all formulations, LPBA consistently improved cell viability, insulin production, mitochondrial activities and ameliorated inflammation.

Conclusion

The deployed biotechnological processes and LPBA optimised formation and functions of β-cell microcapsules, which suggests potential applications in diabetes mellitus via the creation of more stable β-cell microcapsules capable of delivering adequate levels of insulin to control glycaemia and potentially curing diabetes.

Microemulsion based on Pterodon emarginatus oil and its anti-inflammatory potential

This article reports the development of a pharmaceutical product containing vegetable actives from a Brazilian medicinal plant. The possibility of forming a microemulsion using Pterodon emarginatus ("sucupira") oil was evaluated and the anti-inflammatory potential of this microemulsion was also examined. A formulation was developed using P. emarginatus oil, a mixture of ethoxylated Castor Oil (Ultramone(r) R-540/propylene glycol 2:1) (surfactant/cosurfactant) and distilled water at a ratio of 10:15:75, respectively. The microemulsion which was selected was then subjected to the preliminary stability test and analyzed in terms of average diameter of droplets, pH, zeta potential, and polydispersity index, on the 1st, 7th, 15th, and 30th days after preparation and stored at different temperatures (5 ± 2 °C, 25 ± 2 °C, and 40 ± 2 °C). The anti-inflammatory in vivo activity of both oil and formulation were evaluated, using the experimental model of croton oil-induced ear edema. The preliminary stability test showed that the microemulsion stored at 5 and 25 °C retained its original features throughout the 30-day period. The anti-inflammatory potential of both oil and formulation was shown to be statistically significant (p < 0.001), when compared to the control group, however, the microemulsion proved to be more effective (p < 0.05) than the oil when applied directly to the ear.

Influence of emulsifiers on the characteristics of polyurethane structures used as drug carrier

Background

Emulsifiers have a significant role in the emulsion polymerization by reducing the interfacial tension thus increasing the stability of colloidal dispersions of polymer nanostructures. This study evaluates the impact of four emulsifiers on the characteristics of polyurethane hollow structures used as drug delivery system.

Results

Polyurethane (PU) structures with high stability and sizes ranging from nano- to micro-scale were obtained by interfacial polyaddition combined with spontaneous emulsification. The pH of PU aqueous solutions (0.1% w/w) was slightly acidic, which is acceptable for products intended to be used on human skin. Agglomerated structures with irregular shapes were observed by scanning electron microscopy. The synthesized structures have melting points between 245-265°C and reveal promising results in different evaluations (TEWL, mexametry) on murine skin.

Conclusions

In this study hollow PU structures of reduced noxiousness were synthesized, their size and stability being influenced by emulsifiers. Such structures could be used in the pharmaceutical field as future drug delivery systems.

Effect of boundary slip and surface charge on the pressure-driven flow

Drag reduction in micro/nanofluidic systems is an important issue. The effect of boundary slip and electrical double layer (EDL) induced by surface charge on the pressure-driven flow in a micro/nanochannel has been widely studied. However, change in electrical conductivity as a result of ionic redistribution caused by surface charge, which can affect the EDL-induced electrical force exerted on the flow, is often neglected. In addition, the effect of surface charge on the slip length is not considered. In this work, a model incorporating the effect of surface charge on electrical conductivity and slip length was developed to investigate the effect of boundary slip and EDL induced by surface charge on the volumetric flow rate and skin friction coefficient. The underlying mechanisms for the results regarding the effect of slip and surface charge on the flow were analyzed.

Synthesis and preliminary in vivo evaluations of polyurethane microstructures for transdermal drug delivery

Background

Polymers have been considered as important materials in fabrication of microstructures for various medical purposes including drug delivery. This study evaluates polyurethane as material for hollow microstructures preparation.

Results

Polyurethane microstructures were obtained by interfacial polyaddition combined with spontaneous emulsification and present slightly acid pH values. Scanning electron microscopy revealed the existence of irregular shapes and agglomerated microstructures. The material is heat resistant up to 280°C. Good results were recorded on murine skin tests in case of polyurethane microstructures based on isophorone diisocyanate. Mesenchymal stem cells viability presents good results for the same sample after 48 hours based on the Alamar Blue test.

Conclusions

The research revealed the reduced noxiousness of this type of microstructures and consequently the possibility of their use for therapeutic purposes.

The stability mechanisms of an injectable calcium phosphate ceramic suspension

Calcium phosphate ceramics are widely used as bone substitutes in dentistry and orthopedic applications. For minimally invasive surgery an injectable calcium phosphate ceramic suspension (ICPCS) was developed. It consists in a biopolymer (hydroxypropylmethylcellulose: HPMC) as matrix and bioactive calcium phosphate ceramics (biphasic calcium phosphate: BCP) as fillers. The stability of the suspension is essential to this generation of "ready to use" injectable biomaterial. But, during storage, the particles settle down. The engineering sciences have long been interested in models describing the settling (or sedimentation) of particles in viscous fluids. Our work is dedicated to the comprehension of the effect of the formulation on the stability of calcium phosphate suspension before and after steam sterilization. The rheological characterization revealed the macromolecular behavior of the suspending medium. The investigations of settling kinetics showed the influence of the BCP particle size and the HPMC concentration on the settling velocity and sediment compactness before and after sterilization. To decrease the sedimentation process, the granule size has to be smaller and the polymer concentration has to increase. A much lower sedimentation velocity, as compared to Stokes law, is observed and interpreted in terms of interactions between the polymer network in solution and the particles. This experimentation highlights the granules spacer property of hydrophilic macromolecules that is a key issue for interconnection control, one of the better ways to improve osteoconduction and bioactivity.

Long-circulation of hemoglobin-loaded polymeric nanoparticles as oxygen carriers with modulated surface charges

The aim of this study was to investigate the effects of the surface charges on the in vitro macrophage cellular uptake and in vivo blood clearance and biodistribution of the hemoglobin-loaded polymeric nanoparticles (HbPNPs). The surface charges of the HbPNPs fabricated from mPEG-PLA-mPEG were modulated with cationized cetyltrimethylammonium bromide (CTAB) and anionized sodium dodecyl sulphate (SDS), respectively. In vitro macrophage cellular uptake and in vivo biodistribution of the coumarin 6-labeled HbPNPs with different electric charges were investigated, and the half-lives in the circulation were pharmacokinetically analyzed. The particle sizes of the HbPNPs were all below 200 nm with a narrow size distribution and high encapsulation efficiency (>84%). And the zeta-potentials of the untreated, cationized and anionized HbPNPs in phosphate buffered sodium chloride solution (PBS) were -12.3, +3.28 and -25.4 mV, respectively. The HbPNPs did not occur significant aggregation or sedimentation, even after 5 days. Compared with the untreated HbPNPs, 1-fold decrease/increase of the uptake percentage associated with the cationized/anionized HbPNPs was observed. In vivo experiment demonstrated that the calculated half-life of the cationized HbPNPs was 10.991 h, 8-fold longer than that of the untreated HbPNPs (1.198 h). But the anionized HbPNPs displayed opposite effect. Furthermore, the cationized HbPNPs mainly accumulated in the liver, lung and spleen after 48 h injection. MTT results showed that the HbPNPs with different surface charges all exhibited slight toxicity. These results demonstrated that the CTAB-modulated HbPNPs with low positive charge and suitable size have a promising potential as a long-circulating oxygen carrier system with desirable biocompatibility and biofunctionality.

Exposure to copper nanoparticles causes gill injury and acute lethality in zebrafish (Danio rerio)

Increasing use of metallic nanomaterials is likely to result in release of these particles into aqueous environments; however, it is unclear if these materials present a hazard to aquatic organisms. Because some dissolution of metal particles will occur, it is important to distinguish effects of nanoparticulates from dissolved metals. To address this issue, acute toxicity of soluble copper and 80 nm copper nanoparticle suspensions were examined in zebrafish. The results demonstrate that nanocopper is acutely toxic to zebrafish, with a 48 h LC50 concentration of 1.5 mg/L. Rapid aggregation of copper nanoparticles occurred after suspension in water, resulting in 50-60% of added mass leaving the water column. While dissolution of particulate copper occurred, it was insufficient to explain the mortality in nanocopper exposures. Histological and biochemical analysis revealed that the gill was the primary target organ for nanocopper. To further investigate the effects of nanocopper on the gill, zebrafish were exposed to 100 microg/L of nanocopper or to the concentration of soluble copper matching that present due to dissolution of the particles. Under these conditions, nanocopper produced different morphological effects and global gene expression patterns in the gill than soluble copper, clearly demonstrating that the effects of nanocopper on gill are not mediated solely by dissolution.

Development of carbonyl iron/ethylcellulose core/shell nanoparticles for biomedical applications

A reproducible method for the preparation of mixed colloidal nanoparticles, consisting of a magnetic carbonyl iron nucleus and a biocompatible ethylcellulose latex shell, is described in this article. The heterogeneous structure of the particles can confer them both the possibility of being used as drug delivery systems and the responsiveness to external magnetic fields, allowing a selective guidance of drug molecules to specific target tissues without a concurrent increase in its level in healthy tissues. The preparation method is based on an emulsion solvent evaporation process. A complete physicochemical characterization of the composite particles was carried out, and this preliminary investigation showed that the surface behavior of the core/shell particles is similar to that of bare ethylcellulose particles. This was confirmed, in particular, by zeta potential determinations as a function of pH and ionic strength. This fact points to the ethylcellulose shell efficiently coating carbonyl iron, and leading to composite particles which, from the electrokinetic point of view, are almost indistinguishable from latex. The thermodynamic analysis agrees with the electrokinetic one in suggesting that the coverage has been complete, since the components of the surface free energy of mixed particles coincide almost exactly with those corresponding to the cellulose-based pseudolatex. Moreover, the hydrophilic nature of carbonyl iron is modified and the particles become hydrophobic, just like the latex, when they are covered by ethylcellulose. The magnetic behaviors of the carbonyl iron and composite particles were also checked, and the similarities between both types of particles were demonstrated, except that the polymeric shell reduces the magnetization of the sample.

High ionic strength electrokinetics of melamine–formaldehyde latex

The electrokinetic potential of melamine-formaldehyde latex at high ionic strengths was measured by means of two different instruments. The present study confirms that the zeta potentials in 1 M 1-1 electrolyte solutions can be as high as +/-20 mV. The IEP of latex at low ionic strengths was at pH 11. The increase in the electrolyte concentration induced a shift in the IEP to low pH for all studied salts, and this indicates specific adsorption of the anions. The magnitude of the shift depends chiefly on the nature of the anion and increases in the series Cl < NO(3) = Br < I, and the nature of the cation (Li, Na, K, Cs) plays a rather insignificant role.