SAXS studies of the thermally-induced fusion of diblock copolymer spheres: formation of hybrid nanoparticles of intermediate size and shape

Dilute dispersions of poly(lauryl methacrylate)–poly(benzyl methacrylate) (PLMA–PBzMA) diblock copolymer spheres (a.k.a. micelles) of differing mean particle diameter were mixed and thermally annealed at 150 °C to produce spherical nanoparticles of intermediate size. The two initial dispersions were prepared via reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization of benzyl methacrylate in n-dodecane at 90 °C. Systematic variation of the mean degree of polymerization of the core-forming PBzMA block enabled control over the mean particle diameter: small-angle X-ray scattering (SAXS) analysis indicated that PLMA₃₉–PBzMA₉₇ and PLMA₃₉–PBzMA₂₉₄ formed well-defined, non-interacting spheres at 25 °C with core diameters of 21 ± 2 nm and 48 ± 5 nm, respectively. When heated separately, both types of nanoparticles regained their original dimensions during a 25–150–25 °C thermal cycle. However, the cores of the smaller nanoparticles became appreciably solvated when annealed at 150 °C, whereas the larger nanoparticles remained virtually non-solvated at this temperature. Moreover, heating caused a significant reduction in mean aggregation number for the PLMA₃₉–PBzMA₉₇ nanoparticles, suggesting their partial dissociation at 150 °C. Binary mixtures of PLMA₃₉–PBzMA₉₇ and PLMA₃₉–PBzMA₂₉₄ nanoparticles were then studied over a wide range of compositions. For example, annealing a 1.0% w/w equivolume binary mixture led to the formation of a single population of spheres of intermediate mean diameter (36 ± 4 nm). Thus we hypothesize that the individual PLMA₃₉–PBzMA₉₇ chains interact with the larger PLMA₃₉–PBzMA₂₉₄ nanoparticles to form the hybrid nanoparticles. Time-resolved SAXS studies confirm that the evolution in copolymer morphology occurs on relatively short time scales (within 20 min at 150 °C) and involves weakly anisotropic intermediate species. Moreover, weakly anisotropic nanoparticles can be obtained as a final copolymer morphology over a restricted range of compositions (e.g. for PLMA₃₉–PBzMA₉₇ volume fractions of 0.20–0.35) when heating dilute dispersions of such binary nanoparticle mixtures up to 150 °C. A mechanism involving both chain expulsion/insertion and micelle fusion/fission is proposed to account for these unexpected observations.

Dilute dispersions of poly(lauryl methacrylate)-poly(benzyl methacrylate) diblock copolymer spheres of differing mean diameter are mixed and thermally annealed at 150 °C to produce either spherical or non-spherical nanoparticles of intermediate size.     

Extraction Optimization of Astragaloside IV by Response Surface Methodology and Evaluation of Its Stability during Sterilization and Storage

Radix Astragali is referred to as a variety of food-medicine herb, and it is commonly applied as Traditional Chinese Medicine (TCM). However, it is extremely difficult to extract its bio-active compounds (astragaloside IV) and apply it in food processing efficiently, which restricts its practical applications. In this study, the conditions required for the extraction of astragaloside IV were optimized by following the response surface methodology. More specifically, ammonia with a concentration of 24% was used as an extracting solvent, the solid–liquid ratio was 1:10 (w:v); the Radix Astragali was soaked at 25 °C for 120 min in advance and then stirred at 25 °C for 52 min (150 rpm) to extract astragaloside IV. This method promoted the transformation of other astragalosides into astragaloside IV and replaced the traditional approach for extraction, the solvent reflux extraction method. The yield of astragaloside IV reached the range of 2.621 ± 0.019 mg/g. In addition, the stability of astragaloside IV was evaluated by detecting its retention rate during sterilization and 60-day storage. As suggested by the results, the astragaloside IV in acidic, low-acidic, and neutral solutions was maintained above 90% after sterilization (95 °C and 60 min) but below 60% in an alkaline solution. High temperature and short-term sterilization approach is more appropriate for astragaloside IV in an alkaline solution. It was also found out that the astragaloside IV obtained using our method was maintained over 90% when stored at room temperature (25 °C), and there was no significant difference observed to low temperature (4 °C) in solutions regardless of acidity.     

Improved Stability of a Stable Crystal Form C of 6S-5-Methyltetrahydrofolate Calcium Salt,Method Development and Validation of an LC–MS/MS Method for Rat Pharmacokinetic Comparison

Folate is a vitamin beneficial for humans that plays an important role in metabolism, but it cannot be well supplemented by food; it is necessary to supplement it in other ways. Based on this consideration, a novel crystal form C of 6S-5-methyltetrahydrofolate calcium salt (MTHF CAC) was obtained. To explore the difference between MTHF CAC and the crystal form Ⅰ of 6S-5-methyltetrahydrofolate calcium salt (MTHF CA) as well as an amorphous product of 6S-5-methyltetrahydrofolate glucosamine salt (MTHF GA), their stability and pharmacokinetic behaviours were compared. The results of high-performance liquid chromatography coupled with ultraviolet detection analysis indicated that MTHF CAC showed a better stability than MTHF CA and MTHF GA. After oral administration of MTHF CAC, MTHF CA, and MTHF GA to male rats, the MTHF concentrations were analysed using a validated liquid chromatography–tandem mass spectrometry, and the pharmacokinetic parameters were compared. The mean residence times (0–t) of MTHF CAC, MTHF CA, and MTHF GA were 3.7 ± 1.9 h, 1.0 ± 0.2 h (p < 0.01), and 1.5 ± 0.3 h (p < 0.05), respectively. The relative bioavailability of MTHF CAC was calculated to be 351% and 218% compared with MTHF CA and MTHF GA, respectively, which suggests that MTHF CAC can be better absorbed and utilized for a longer period of time.     

The Quenching and Sonication Effect on the Mechanical Strength of Silver Nanowires Synthesized Using the Polyol Method

This study aims to determine the effect of fast cooling (quenching) on thermal properties, mechanical strength, morphology and size of the AgNWs. The synthesis of AgNWs was carried out at three different quenching-medium temperatures as follows: at 27 °C (ambient temperature), 0 °C (on ice), and −80 °C (in dry ice) using the polyol method at 130 °C. Furthermore, the AgNWs were sonified for 45 min to determine their mechanical strength. Scanning electron microscopy analysis showed that the quenched AgNWs had decreased significantly; at 27 °C, the AgNWs experienced a change in length from (40 ± 10) to (21 ± 6) µm, at 0 °C from (37 ± 8) to (24 ± 8) µm, and at −80 °C from (34 ± 9) to (29 ± 1) µm. The opposite occurred for their diameter with an increased quenching temperature: at 27 °C from (200 ± 10) to (210 ± 10) nm, at 0 °C from (224 ± 4) to (239 ± 8) nm, and at −80 °C from (253 ± 6) to (270 ± 10) nm. The lower the temperature of the quenching medium, the shorter the length and the higher the mechanical strength of AgNWs. The UV-Vis spectra of the AgNWs showed peak absorbances at 350 and 411 to 425 nm. Thermogravimetric analysis showed that AgNWs quenched at −80 °C have better thermal stability as their mass loss was only 2.88%, while at the quenching temperatures of 27 °C and 0 °C the mass loss was of 8.73% and 4.17%, respectively. The resulting AgNWs will then be applied to manufacture transparent conductive electrodes (TCEs) for optoelectronic applications.     

Psychrotolerant Mesorhizobium sp. Isolated from Temperate and Cold Desert Regions Solubilizes Potassium and Produces Multiple Plant Growth Promoting Metabolites

Soil potassium (K) supplement depends intensively on the application of chemical fertilizers, which have substantial harmful environmental effects. However, some bacteria can act as inoculants by converting unavailable and insoluble K forms into plant-accessible forms. Such bacteria are an eco-friendly approach for enhancing plant K absorption and consequently reducing utilization of chemical fertilization. Therefore, the present research was undertaken to isolate, screen, and characterize the K solubilizing bacteria (KSB) from the rhizosphere soils of northern India. Overall, 110 strains were isolated, but only 13 isolates showed significant K solubilizing ability by forming a halo zone on solid media. They were further screened for K solubilizing activity at 0 °C, 1 °C, 3 °C, 5 °C, 7 °C, 15 °C, and 20 °C for 5, 10, and 20 days. All the bacterial isolates showed mineral K solubilization activity at these different temperatures. However, the content of K solubilization increased with the upsurge in temperature and period of incubation. The isolate KSB (Grz) showed the highest K solubilization index of 462.28% after 48 h of incubation at 20 °C. The maximum of 23.38 µg K/mL broth was solubilized by the isolate KSB (Grz) at 20 °C after 20 days of incubation. Based on morphological, biochemical, and molecular characterization (through the 16S rDNA approach), the isolate KSB (Grz) was identified as Mesorhizobium sp. The majority of the strains produced HCN and ammonia. The maximum indole acetic acid (IAA) (31.54 µM/mL) and cellulase (390 µM/mL) were produced by the isolate KSB (Grz). In contrast, the highest protease (525.12 µM/mL) and chitinase (5.20 µM/mL) activities were shown by standard strain Bacillus mucilaginosus and KSB (Gmr) isolate, respectively.     

Influence of Carbon Nanotubes on Phase Composition,Thermal and Post-Heating Behavior of Cementitious Composites

This paper experimentally investigates the influence of carbon nanotubes (CNTs) on phase composition, microstructure deterioration, thermal behavior, and residual mechanical strengths of cementitious composites exposed to elevated temperatures. Cement mortars with small dosages of CNTs, 0.05% and 0.2% by weight of cement, were prepared and then heated at 25 °C, 150 °C, 200 °C, 450 °C, and 600 °C for two hours before being tested. The results show positive impact of the CNTs on the hydration process of cement mortar at room temperature and at higher temperatures up to 200 °C. Decomposition of the hydration products is obvious at 450 °C, whereas sever deterioration in the microstructure occurs at 600 °C. The nano reinforcement and bridging effect of the CNTs are obvious up to 450 °C. Thermal behavior characterization shows that CNTs incorporation enhances the thermal conductivity of the unheated and heat-treated mortar specimens. The decomposition of the hydration products needs more heat in the presence of CNTs. Finally, presence of CNTs significantly enhances the residual compressive and flexural strengths of heated mortar specimens for all studied temperatures.     

Thermodynamic Assessment of a Solar-Driven Integrated Membrane Reactor for Ethanol Steam Reforming

To efficiently convert and utilize intermittent solar energy, a novel solar-driven ethanol steam reforming (ESR) system integrated with a membrane reactor is proposed. It has the potential to convert low-grade solar thermal energy into high energy level chemical energy. Driven by chemical potential, hydrogen permeation membranes (HPM) can separate the generated hydrogen and shift the ESR equilibrium forward to increase conversion and thermodynamic efficiency. The thermodynamic and environmental performances are analyzed via numerical simulation under a reaction temperature range of 100–400 °C with permeate pressures of 0.01–0.75 bar. The highest theoretical conversion rate is 98.3% at 100 °C and 0.01 bar, while the highest first-law efficiency, solar-to-fuel efficiency, and exergy efficiency are 82.3%, 45.3%, and 70.4% at 215 °C and 0.20 bar. The standard coal saving rate (SCSR) and carbon dioxide reduction rate (CDRR) are maximums of 101 g·m⁻²·h⁻¹ and 247 g·m⁻²·h⁻¹ at 200 °C and 0.20 bar with a hydrogen generation rate of 22.4 mol·m⁻²·h⁻¹. This study illustrates the feasibility of solar-driven ESR integrated with a membrane reactor and distinguishes a novel approach for distributed hydrogen generation and solar energy utilization and upgradation.     

CO2 hydrogenation to methanol and dimethyl ether at atmospheric pressure using Cu-Ho-Ga/γ–Al2O3 and Cu-Ho-Ga/ZSM-5: Experimental study and thermodynamic analysis

CO₂ valorization through chemical reactions attracts significant attention due to the mitigation of greenhouse gas effects. This article covers the catalytic hydrogenation of CO₂ to methanol and dimethyl ether using Cu-Ho-Ga containing ZSM-5 and g-Al₂O₃ at atmospheric pressure and at temperatures of 210 °C and 260 °C using a CO₂:H₂ feed ratio of 1:3 and 1:9. In addition, the thermodynamic limitations of methanol and DME formation from CO₂ was investigated at a temperature range of 100–400 °C. Cu-Ho-Ga/g-Al₂O₃ catalyst shows the highest formation rate of methanol (90.3 µmol_CH3OH/g_cat/h ) and DME (13.2 µmol_DME/g_cat/h) as well as the highest selectivity towards methanol and DME (39.9 %) at 210 °C using a CO₂:H₂ 1:9 feed ratio. In both the thermodynamic analysis and reaction results, the higher concentration of H₂ in the feed and lower reaction temperature resulted in higher DME selectivity and lower CO production rates.     

Mechanochemical Synthesis and Nitrogenation of the Nd1.1Fe10CoTi Alloy for Permanent Magnet

In this work, the mechanochemical synthesis method was used for the first time to produce powders of the nanocrystalline Nd_1.1Fe₁₀CoTi compound from Nd₂O₃, Fe₂O₃, Co and TiO₂. High-energy-milled powders were heat treated at 1000 °C for 10 min to obtain the ThMn₁₂-type structure. Volume fraction of the 1:12 phase was found to be as high as 95.7% with 4.3% of a bcc phase also present. The nitrogenation process of the sample was carried out at 350 °C during 3, 6, 9 and 12 h using a static pressure of 80 kPa of N₂. The magnetic properties M_r, µ₀H_c, and (BH)_max were enhanced after nitrogenation, despite finding some residual nitrogen-free 1:12 phase. The magnetic values of a nitrogenated sample after 3 h were M_r = 75 Am² kg^–1, µ₀H_c = 0.500 T and (BH)_max = 58 kJ·m^–3. Samples were aligned under an applied field of 2 T after washing and were measured in a direction parallel to the applied field. The best value of (BH)_max ~ 114 kJ·m^–3 was obtained for 3 h and the highest µ₀H_c = 0.518 T for 6 h nitrogenation. SEM characterization revealed that the particles have a mean particle size around 360 nm and a rounded shape.     

The Effects of Prolonged Storage on ARPE-19 Cells Stored at Three Different Storage Temperatures

This study aimed to investigate how prolonged storage of adult retinal pigment epithelial (ARPE-19) cell sheets affects cell metabolism, morphology, viability, and phenotype. ARPE-19 cell sheets were stored at three temperatures (4 °C, 16 °C, and 37 °C) for three weeks. Metabolic status and morphology of the cells were monitored by sampling medium and examining cells by phase-contrast microscopy, respectively, throughout the storage period. Cell viability was analyzed by flow cytometry, and phenotype was determined by epifluorescence microscopy after the storage. Lactate production and glucose consumption increased heavily, while pH dropped considerably, through storage at 37 °C compared to 4 °C and 16 °C. During storage, morphology started to deteriorate first at 4 °C, then at 37 °C, and was maintained the longest at 16 °C. Viability of the cells after three weeks of storage was best preserved at 16 °C, while cells stored at 4 °C and 37 °C had reduced viability. Dedifferentiation indicated by reduced expression of retinal pigment epithelium-specific protein 65 (RPE65), zonula occludens protein 1 (ZO-1), and occludin after three weeks of storage was noticed in all experimental groups compared to control. We conclude that storage temperature affects the metabolic status of ARPE-19 cells and that 16 °C reduces metabolic activity while protecting viability and morphology.     

Validation of a Simple HPLC-Based Method for Lysine Quantification for Ruminant Nutrition

Robust and selective quantification methods are required to better analyze feed supplementation effectiveness with specific amino acids. In this work, a reversed-phase high-performance liquid chromatography method with fluorescence detection is proposed and validated for lysine quantification, one of the most limiting amino acids in ruminant nutrition and essential towards milk production. To assess and widen method applicability, different matrices were considered: namely Li₂CO₃ buffer (the chosen standard reaction buffer), phosphate buffer solution (to mimic media in cellular studies), and rumen inoculum. The method was validated for all three matrices and found to be selective, accurate (92% ± 2%), and precise at both the inter- and intra-day levels in concentrations up to 225 µM, with detection and quantification limits lower than 1.24 and 4.14 µM, respectively. Sample stability was evaluated when stored at room temperature, 4 °C, and −20 °C, showing consistency for up to 48 h regardless of the matrix. Finally, the developed method was applied in the quantification of lysine on real samples. The results presented indicate that the proposed method can be applied towards free lysine quantification in ruminant feeding studies and potentially be of great benefit to dairy cow nutrition supplementation and optimization.     

Physicochemical Properties and Antioxidant Activity of Spray-Dry Broccoli (Brassica oleracea var Italica) Stalk and Floret Juice Powders

This research presents the microencapsulation and conservation of antioxidants of broccoli juice processed by spray drying, and proposes the use of a by-product as a technological application. Broccoli juice (BJ) extracted from two sources, stalks and florets, was spray-dried employing maltodextrin (MX) as a carrier agent at concentrations of 5, 7.5, and 10%, and inlet temperatures of 150 and 220 °C. The total phenolic content (TPC), and antioxidant activity (AA) of the BJ-MX powders were determined together with the physicochemical characteristics, including particle morphology, microstructure, and thermal properties. Based on the TPC and AA, the optimal processing conditions found were 5% of MX and a drying temperature of 220 °C. However, the florets showed higher TPC, while stalks presented higher AA under those processing conditions. The particles exhibited micrometric sizes and a mixture of spherical-shape particles and pseudo-spherical particles. The diffractograms indicated an amorphous microstructure in all samples. The glass transition temperature (Tg) was determined in the range of 50 °C for the samples dried at 150 °C and 55 °C for those dried at 220 °C. This suggested that powders might be stored at temperatures below the Tg without presenting any loss of antioxidants.     

Inhibitory Effects of Erythrosine/Curcumin Derivatives/Nano-Titanium Dioxide-Mediated Photodynamic Therapy on Candida albicans

This study focuses on the role of photosensitizers in photodynamic therapy. The photosensitizers were prepared in combinations of 110/220 µM erythrosine and/or 10/20 µM demethoxy/bisdemethoxy curcumin with/without 10% (w/w) nano-titanium dioxide. Irradiation was performed with a dental blue light in the 395–480 nm wavelength range, with a power density of 3200 mW/cm² and yield of 72 J/cm². The production of ROS and hydroxyl radical was investigated using an electron paramagnetic resonance spectrometer for each individual photosensitizer or in photosensitizer combinations. Subsequently, a PrestoBlue^® toxicity test of the gingival fibroblast cells was performed at 6 and 24 h on the eight highest ROS-generating photosensitizers containing curcumin derivatives and erythrosine 220 µM. Finally, the antifungal ability of 22 test photosensitizers, Candida albicans (ATCC 10231), were cultured in biofilm form at 37 °C for 48 h, then the colonies were counted in colony-forming units (CFU/mL) via the drop plate technique, and then the log reduction was calculated. The results showed that at 48 h the test photosensitizers could simultaneously produce both ROS types. All test photosensitizers demonstrated no toxicity on the fibroblast cells. In total, 18 test photosensitizers were able to inhibit Candida albicans similarly to nystatin. Conclusively, 20 µM bisdemethoxy curcumin + 220 µM erythrosine + 10% (w/w) nano-titanium dioxide exerted the highest inhibitory effect on Candida albicans.     

Thermal Degradation of Linalool-Chemotype Cinnamomum osmophloeum Leaf Essential Oil and Its Stabilization by Microencapsulation with β-Cyclodextrin

The thermal degradation of linalool-chemotype Cinnamomum osmophloeum leaf essential oil and the stability effect of microencapsulation of leaf essential oil with β-cyclodextrin were studied. After thermal degradation of linalool-chemotype leaf essential oil, degraded compounds including β-myrcene, cis-ocimene and trans-ocimene, were formed through the dehydroxylation of linalool; and ene cyclization also occurs to linalool and its dehydroxylated products to form the compounds such as limonene, terpinolene and α-terpinene. The optimal microencapsulation conditions of leaf essential oil microcapsules were at a leaf essential oil to the β-cyclodextrin ratio of 15:85 and with a solvent ratio (ethanol to water) of 1:5. The maximum yield of leaf essential oil microencapsulated with β-cyclodextrin was 96.5%. According to results from the accelerated dry-heat aging test, β-cyclodextrin was fairly stable at 105 °C, and microencapsulation with β-cyclodextrin can efficiently slow down the emission of linalool-chemotype C. osmophloeum leaf essential oil.     

Comprehensive Thermal Characteristics of Different Cultivars of Flaxseed Oil (Linum usittatissimum L.)

The aim of this study was to describe the thermal properties of selected cultivars of flaxseed oil by the use of the differential scanning calorimetry (DSC) technique. The crystallization and melting profiles were analyzed depending on different scanning rates (1, 2, 5 °C/min) as well as oxidative induction time (OIT) isothermally at 120 °C and 140 °C, and oxidation onset temperatures (Ton) at 2 and 5 °C/min were measured. The crystallization was manifested as a single peak, differing for a cooling rate of 1 and 2 °C/min. The melting curves were more complex with differences among the cultivars for a heating rate of 1 and 2 °C/min, while for 5 °C/min, the profiles did not differ, which could be utilized in analytics for profiling in order to assess the authenticity of the flaxseed oil. Moreover, it was observed that flaxseed oil was highly susceptible to thermal oxidation, and its stability decreased with increasing temperature and decreasing heating rate. Significant negative linear correlations were found between unsaturated fatty acid content (C18:2, C18:3 n-3) and DSC parameters (OIT, Ton). Principal component analysis (PCA) also established a strong correlation between total oxidation value (TOTOX), peroxide value (PV) and all DSC parameters of thermo-oxidative stability.     

Biochemical Studies in Perfundates and Homogenates of Isolated Porcine Kidneys after Flushing with Zinc or Zinc–Prolactin Modified Preservation Solution Using a Static Cold Storage Technique

Zinc is an effective anti-inflammatory and antioxidant trace element. The aim of this study was to analyse the protective effect of zinc and zinc–prolactin systems as additives of preservation solutions in the prevention of nephron damage caused during ischemia. The study used a model for storing isolated porcine kidneys in Biolasol^®. The solution was modified with the addition of Zn at a dose of 1 µg/L and Zn: 1 µg/L with prolactin (PRL): 0.1 µg/L. After 2 h and 48 h of storage, the levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, sodium, potassium, creatinine and total protein were determined. Zinc added to the Biolasol^® composition at a dose of 1 µg/L showed minor effectiveness in the protection of nephrons. In turn, Zn²⁺ added to Biolasol + PRL (PRL: 0.1 µg/L) acted as a prolactin inhibitor. We do not recommend the addition of Zn(II) (1 µg/L) and Zn(II) (1 µg/L) + PRL (0.1 µg/L) to the Biolasol solution.     

Effect of pH and Pea Protein: Xanthan Gum Ratio on Emulsions with High Oil Content and High Internal Phase Emulsion Formation

Electrostatic interaction between protein and polysaccharides could influence structured liquid oil stability when emulsification is used for this purpose. The objective of this work was to structure sunflower oil forming emulsions and High Internal Phase Emulsions (HIPEs) using pea protein (PP) and xanthan gum (XG) as a stabilizer, promoting or not their electrostatic attraction. The 60/40 oil-in-water emulsions were made varying the pH (3, 5, and 7) and PP:XG ratio (4:1, 8:1, and 12:1). To form HIPEs, samples were oven-dried and homogenized. The higher the pH, the smaller the droplet size (Emulsions: 15.60–43.96 µm and HIPEs: 8.74–20.38 µm) and the oil release after 9 weeks of storage at 5 °C and 25 °C (oil loss < 8%). All systems had weak gel-like behavior, however, the values of viscoelastic properties (G′ and G″) increased with the increment of PP:XG ratio. Stable emulsions were obtained at pHs 5 and 7 in all PP:XG ratios, and at pH 3 in the ratio 4:1. Stable HIPEs were obtained at pH 7 in the ratios PP:XG 4:1, 8:1, and 12:1, and at pH 5 at PP:XG ratio 4:1. All these systems presented different characteristics that could be exploited for their application as fat substitutes.     

Preparation of Amylose-Oligo[(R)-3-hydroxybutyrate] Inclusion Complex by Vine-Twining Polymerization

In this study, we attempted to prepare an amylose-oligo[(R)-3-hydroxybutyrate] (ORHB) inclusion complex using a vine-twining polymerization approach. Our previous studies indicated that glucan phosphorylase (GP)-catalyzed enzymatic polymerization in the presence of appropriate hydrophobic guest polymers produces the corresponding amylose–polymer inclusion complexes, a process named vine-twining polymerization. When vine-twining polymerization was conducted in the presence of ORHB under general enzymatic polymerization conditions (45 °C), the enzymatically produced amylose did not undergo complexation with ORHB. However, using a maltotriose primer in the same polymerization system at 70 °C for 48 h to obtain water-soluble amylose, called single amylose, followed by cooling the system over 7 h to 45 °C, successfully induced the formation of the inclusion complex. Furthermore, enzymatic polymerization initiated from a longer primer under the same conditions induced the partial formation of the inclusion complex. The structures of the different products were analyzed by X-ray diffraction, ¹H-NMR, and IR measurements. The mechanism of formation of the inclusion complexes discussed in the study is proposed based on the additional experimental results.     

Supercritical CO2 Assisted Impregnation of Ibuprofen on Medium-Chain-Length Polyhydroxyalkanoates (mcl-PHA)

In this work, we propose the utilization of scCO₂ to impregnate ibuprofen into the mcl-PHA matrix produced by Pseudomonas chlororaphis subs. aurantiaca (DSM 19603). The biopolymer has adhesive properties, is biocompatible and has a melting temperature of 45 °C. Several conditions, namely, pressure (15 and 20 MPa) and impregnation time (30 min, 1 h and 3 h) were tested. The highest ibuprofen content (90.8 ± 6.5 mg of ibuprofen/g_PHA) was obtained at 20 MPa and 40 °C, for 1 h, with an impregnation rate of 89 mg/(g·h). The processed mcl-PHA samples suffered a plasticization, as shown by the decrease of 6.5 °C in the T_g, at 20 MPa. The polymer’s crystallinity was also affected concomitantly with the matrices’ ibuprofen content. For all the impregnation conditions tested the release of ibuprofen from the biopolymer followed a type II release profile. This study has demonstrated that the mcl-PHA produced by P. chlororaphis has a great potential for the development of novel topical drug delivery systems.     

Doxycycline Interferes with Zika Virus Serine Protease and Inhibits Virus Replication in Human Skin Fibroblasts

Zika virus (ZIKV) represents a re-emerging threat to global health due to its association with congenital birth defects. ZIKV NS2B-NS3 protease is crucial for virus replication by cleaving viral polyprotein at various junctions to release viral proteins and cause cytotoxic effects in ZIKV-infected cells. This study characterized the inhibitory effects of doxycycline against ZIKV NS2B-NS3 protease and viral replication in human skin cells. The in silico data showed that doxycycline binds to the active site of ZIKV protease at a low docking energy (−7.8 Kcal/mol) via four hydrogen bonds with the protease residues TYR1130, SER1135, GLY1151, and ASP83. Doxycycline efficiently inhibited viral NS2B-NS3 protease at average human temperature (37 °C) and human temperature with a high fever during virus infection (40 °C). Interestingly, doxycycline showed a higher inhibitory effect at 40 °C (IC50 = 5.3 µM) compared to 37 °C (9.9 µM). The virus replication was considerably reduced by increasing the concentration of doxycycline. An approximately 50% reduction in virus replication was observed at 20 µM of doxycycline. Treatment with 20 µM of doxycycline reduced the cytopathic effects (CPE), and the 40 µM of doxycycline almost eliminated the CPE of human skin cells. This study showed that doxycycline binds to the ZIKV protease and inhibits its catalytic activity at a low micro-molecular concentration range. Treatment of human skin fibroblast with doxycycline eliminated ZIKV infection and protected the cells against the cytopathic effects of the infection.