Smooth Surface Research Articles

Water-Etched Porous Ti: Surface Manipulation of Ti Foam Fabricated by Liquid Metal Dealloying Technique.

The liquid metal dealloying (LMD) process enables the fabrication of porous metals with various chemical compositions. Despite its advantages, LMD still faces key challenges such as maintaining the high-temperature molten metal bath for a prolonged time, avoiding the use of toxic etchants, and so on. To overcome these challenges, the study develops a water-leachable and oxidation-resistant alloy melt (AM) in Ca-Mg binary system. Specifically, Ca72Mg28 eutectic AM is designed, which exhibits higher oxidation resistance and lower melting temperature compared to pure Mg, allowing LMD to be conducted in atmospheric conditions as well as temperatures >200K lower. The AM also enables an innovative process to fabricate Ti foams with a hexagonal faceted surface structure by carefully manipulating the etching rate during the water etching process. This approach allows for the creation of foam with a surface area over 13% larger than that of foams with smooth surfaces via normal acid etching, potentially enhancing efficiency in applications such as electrodes for electrochemical systems or biomedical materials where increased cell adhesion can be beneficial. This study paves the way for efficiently manipulating the LMD process to fabricate metal foams with customized compositions and enhanced surface properties.

Physical field of dual-frequency ultrasonic vibration and its effect on solidification behavior of MgZnY alloy

A three-dimensional model was established for coupled simulation of the physical field in a liquid subjected to dual-frequency ultrasonic vibration. The effect of sonotrode position, tip shape, and vessel on the distributions of acoustic pressure and acoustic streaming were clarified. The influence of physical fields on the solidification behavior of Mg alloy was investigated. The simulation results show that the interaction between the two ultrasounds was weakened as the sonotrode spacing increased, and the radiating angle had little effect on the acoustic pressure distribution. The volume mean pressure in the liquid radiated by the plane tip was the smallest, but with the greatest acoustic streaming intensity. In contrast, the spherical tip radiated the highest volume mean pressure in the liquid medium, but the acoustic streaming was severely suppressed. Attributed to the smooth spherical surface that facilitated fluid flow, high flow velocity could be achieved using a round-bottomed crucible without severe acoustic pressure attenuation. The experimental results show that cavitation and acoustic flow caused the coarse dendrites to turn into fine isometric crystals. The acoustic flow accelerated the melt flow and alleviated the segregation and precipitation of Zn elements, leading to a decrease in the content and size of the second phase in the billet.

Temperature-regulating functional PET composite fabric based on paraffin@silicon dioxide microencapsulated phase change materials

A novel kind of thermoregulatory composite fabric was prepared in this work. Firstly, paraffin@silicon dioxide (Pn@SiO2) microencapsulated phase change microcapsules (MEPCM) were synthesized by sol-gel method with paraffin as the core and silica dioxide as the shell. The spherical MEPCM with a particle size distribution of 6–12 μm exhibited a smooth surface. The heat storage capacity of MEPCM was tested by DSC, showing the phase change enthalpy of 137.3 J/g. Then, MEPCM was coated onto PET textile fabric, and the effect of different content of MEPCM on the temperature regulation performance of the finishing fabric was discussed. MEPCM on the surface morphology, thermal regulating properties, and thermal effects of the fabric were investigated by SEM, DSC, TG, infrared thermography, and photo thermal experiment. The highest enthalpy of the composite fabric after finishing by MEPCM could reach 49.18 J/g, and the infrared thermography showed that the rate of temperature change of the composite fabric was significantly slowed down during the warming and cooling process, which had the ideal heat storage and temperature regulation function. Phase change composite fabric shows great potential in a wide range of applications, such as military firefighting, personal protection, and temperature-controllable advanced textiles.

Making Healthcare Accessible: A Rapid Clean-Room-Free Fabrication Strategy for Microfluidics-Driven Biosensors Based on Coupling Stereolithography and Hot Embossing.

Microfluidics offers transformative potential in healthcare by enabling miniaturized, user-friendly, and cost-effective devices for disease diagnostics among other biomedical applications; however, their meaningful adoption is severely hindered, especially in developing countries and resource-limited settings, by the cost, time, and complexity of their fabrication. To overcome this barrier of access, this work develops a novel approach for highly efficient (<4 h), cost-effective, and clean-room-free fabrication of functional polydimethylsiloxane (PDMS)-based microfluidic devices based on coupling stereolithography three-dimensional (3D) printing with hot embossing. The strategy exhibits high fidelity between the digital design and final device, remarkable transfer accuracy between the 3D print and poly(methyl methacrylate) (PMMA) mold, in addition to highly smooth surfaces (R a < 1 μm). To establish the versatility of the approach and performance quality of the fabricated devices, three advanced microfluidics-driven biosensing platforms are developed: a microsphere droplet generator, a stop-flow lithography-based hydrogel microparticle synthesizer, and a hydrogel postembedded microfluidic device for multiplexed biomarker detection. As a proof-of-concept, the latter platform was applied to the multiplexed detection of microRNA, a highly promising class of liquid biopsy biomarkers for many diseases including cancer. Notably, the ability to demonstrate multiplexed sensing of disease biomarkers within devices made through a facile, rapid, and clean-room-free strategy demonstrates the immense potential of this fabrication approach to accelerate the adoption and advancement of biomedical microfluidic devices in practice and in resource-limited settings.

Microbicidal Polymer Nanoparticles Containing Clotrimazole for Treatment of Vulvovaginal Candidiasis

Vulvovaginal candidiasis (VVC) alters the innate cervicovaginal immunity, which provides an important barrier against viruses and other infections. The incidence of this disease has not decreased in the last 30 years, so effective treatments are still needed. Nanoparticles (NPs) of cellulose acetate phthalate (CAP) and clotrimazole (CLZ) were prepared by the emulsification-diffusion method. NPs were characterized using dynamic light scattering, atomic force microscopy and differential scanning calorimetry; their release profile was determined by the dialysis bag technique and mucoadhesion was evaluated with the mucin-particle method. The growth inhibition study of Candida albicans was carried out using the plate counting technique. Finally, accelerated physical stability tests of NPs were carried out, both in water and in SVF. The CAP-CLZ NPs had an average diameter of 273.4 nm, a PDI of 0.284, smooth surfaces and spherical shapes. In vitro release of CLZ from the CAP NPs was categorized with the Weibull model as a matrix system in which initial release was rapid and subsequently sustained. The inhibition of C. albicans growth by the CAP-CLZ NPs was greater than that of free CLZ, and the CAP-only NPs had a microbicidal effect on C. albicans. The NPs showed poor mucoadhesiveness, which could lead to studies of their mucopenetration capacities. An accelerated physical stability test revealed the erosion of CAP in aqueous media. A nanoparticulate system was developed and provided sustained release of CLZ, and it combined an antifungal agent with a microbial polymer that exhibited antifungal activity against C. albicans.Graphical

Influence of deposition pressure on microstructure, mechanical and electrical properties of niobium thin films

Niobium (Nb) thin films were deposited on a Si substrate using magnetron sputtering system by varying the deposition pressure. The effect of deposition pressure on the microstructure, residual stresses, and electrical properties was investigated by systematically varying the deposition pressure from 0.15 to 0.60 Pa. The Nb thin films were characterized using hard x-ray reflectivity, grazing incidence x-ray diffraction, four point probe method, and atomic force microscopy. The films grown at lower deposition pressures had smooth surfaces and more compact structures, which are advantageous for lowering electrical resistance but had higher compressive stress. On the other hand, the films grown at higher deposition pressures had columnar type growth with less dense structures, which leads to increase in electrical resistance. However the nature of stresses transform from compressive to tensile. Hard X-ray reflectivity performed on Nb films provides direct insight into the growth and the microstructure which were correlated with the mechanical and electrical properties.

Mechanical properties and strain rate effect of graphene oxide grafted carbon fiber modified concrete under dynamic impact load

In order to improve the shortcomings of carbon fiber, such as smooth surface, poor bonding with concrete matrix and easy to pull out under dynamic impact load, graphene oxide is grafted onto the surface of carbon fiber by chemical bonds to prepare graphene oxide grafted carbon fiber (CF-GO). The dynamic impact test on CF-GO modified concrete (CF-GOMC) is carried out by the split hopkinson pressure bar (SHPB) test system, and the mechanical properties and strain rate effect of CF-GOMC under dynamic impact loads are studied. The modification mechanism of CF-GO is analyzed by microscopic tests. The results show that compared with carbon fiber, the surface roughness and surface area of CF-GO increase and CF-GO is more suitable for bonding with concrete matrix. CF-GO can improve the mechanical properties of concrete under dynamic impact load and enhance the strain rate effect of dynamic mechanical properties indicators by preventing crack, bridging, filling and promoting hydration. With the increase of CF-GO content, the dynamic mechanical properties and strain rate sensitivity of CF-GOMC increase first and then decrease. The optimal content of CF-GO is 0.3 %. The improvement effect of CF-GO on the dynamic mechanical properties and strain rate effect of concrete is better than that of carbon fiber. The graphene oxide on the surface of CF-GO makes the interface of CF-GO/concrete matrix compact by improving the mechanical bite force of fiber/concrete matrix and promoting the formation of hydration products on the surface of fiber. The addition of CF-GO does not change the composition of cement hydration products, but promotes the crystal growth of hydration products and optimizes the pore structure of concrete.

The flux pinning effect of different doping element combinations on metal-organic deposition-derived YBa2Cu3O7−δ nanocomposite films

Elemental doping has been proven effective in improving the flux pinning of yttrium barium copper oxide (YBa2Cu3O7−δ, YBCO) nanocomposite thin films. In the present work, we increased the number of doping elements to five to investigate the flux pinning effect of YBCO. The Zr-doped, Zr, Hf and Sn co-doped, Zr, Hf, Sn and Ta co-doped, and Zr, Hf, Sn, Ta and Mn co-doped YBCO films deposited on LaMnO3/MgO/Y2O3/Al2O3/ Hastelloy substrate were systematically studied. The samples were prepared by low-fluorine metal-organic deposition method, with a total dopant of 8 mol%. All films exhibit good c-axis growth and the multi-doping helps refining the surface particles, resulting in a smoother surface. The in-field properties of the films increase with the increase of co-doped element numbers, especially at a low temperature of 30 K. The pinning force density (Fp) and critical current density (Jc) are significantly improved by five-element Zr, Hf, Sn, Ta and Mn co-doped, which is about 3 times and 1.6 times higher, respectively, than that of the undoped film at 30 K and 1 T.

Emulsion electrospun epigallocatechin gallate-loaded silk fibroin/polycaprolactone nanofibrous membranes for enhancing guided bone regeneration

Guided bone regeneration (GBR) membranes play an important role in oral bone regeneration. However, enhancing their bone regeneration potential and antibacterial properties is crucial. Herein, silk fibroin (SF)/polycaprolactone (PCL) core-shell nanofibers loaded with epigallocatechin gallate (EGCG) were prepared using emulsion electrospinning. The nanofibrous membranes were characterized via scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, water contact angle (CA) measurement, mechanical properties testing, drug release kinetics, and 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) free radical scavenging assay. Mouse pre-osteoblast MC3T3-E1 cells were used to assess the biological characteristics, cytocompatibility, and osteogenic differentiation potential of the nanofibrous membrane. Additionally, the antibacterial properties againstStaphylococcus aureus (S. aureus)andEscherichia coli (E. coli)were evaluated. The nanofibers prepared by emulsion electrospinning exhibited a stable core-shell structure with a smooth and continuous surface. The tensile strength of the SF/PCL membrane loaded with EGCG was 3.88 ± 0.15 Mpa, the water CA was 50°, and the DPPH clearance rate at 24 h was 81.73% ± 0.07%. The EGCG release rate of membranes prepared by emulsion electrospinning was reduced by 12% within 72 h compared to that of membranes prepared via traditional electrospinning.In vitroexperiments indicate that the core-shell membranes loaded with EGCG demonstrated good cell compatibility and promoted adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. Furthermore, the EGCG-loaded membranes exhibited inhibitory effects onE. coliandS. aureus. These findings indicate that core-shell nanofibrous membranes encapsulated with EGCG prepared using emulsion electrospinning possess good antioxidant, osteogenic, and antibacterial properties, making them potential candidates for research in GBR materials.

Anti-Corrosion Flocking Surface with Enhanced Wettability and Evaporation.

The corrosion protection of tool steel surfaces is of significant importance for ensuring cutting precision and cost savings. However, conventional surface protection measures usually rely on toxic organic solvents, posing threats to the environment and human health. In this regard, an integrated process of laser texturing and electrostatic flocking is introduced as a green anti-corrosion method on a high-speed steel (HSS) surface. Drawing from the principles of textured surface energy barrier reduction and fiber array capillary water evaporation enhancement, a flocking surface with a synergistic optimization of surface wettability and evaporation performance was achieved. Then, contact corrosion tests using 0.1 mol/L of NaCl droplets were performed. Contact angles representing wettability and change in droplet mass representing evaporation properties were collected. The elements and chemical bonds presented on the corroded surfaces were characterized by X-ray photoelectron spectroscopy (XPS). The results revealed that the flocking surface exhibited the lowest degree of corrosion when compared with smooth and textured surfaces. Corrosion resistance of the flocking surface was achieved through the rapid spread and evaporation of droplets, which reduced the reaction time and mitigated electrochemical corrosion. This innovative flocking surface holds promise as an effective treatment in anti-corrosion strategies for cutting tools.

Synthesis of tungsten-doped zinc oxide nanoparticles using Aloe vera extracts for perovskite solar cells

A green, plant extract-mediated synthesis technique utilizing the Aloe vera stem extract with Zinc acetate (Zn(CH₃CO₂)₂·2H₂O), and Tungsten chloride (WCl2) salt has been employed to grow Zinc Oxide (ZnO) and tungsten doped ZnO (W-ZnO) nanoparticles (NPs). The formation of NPs was confirmed by FESEM with EDX and TEM analysis. The synthesized NPs have been employed for fabricating ZnO and W-ZnO thin films and the electro-optical properties of the films have also been investigated in detail. The thin films have obtained via spin coating and followed by annealing at 350 °C for 3 h in an ambiance atmosphere. The films showed smooth surfaces with a bandgap of 3.20 and 3.25 eV for ZnO and W-ZnO respectively. Finally, a novel structure inverted perovskite solar cells (PSCs) has been numerically analyzed utilizing the films as an electron transporting layer (ETL) for realizing the device performance. The highest PCE of the device for synthesized ZnO and W-ZnO has been found to be 21.16 % and 23.61 %, respectively. All of the findings show that the W-ZnO film is more suitable for the fabrication of PSCs than the ZnO film. In a nutshell, the synthesis of W-ZnO NPs employing green and eco-friendly methods, mediated by Aloe vera extract as the reducing agent, offers in this study a novel approach to enhancing solar cell efficiency with the simple spin coating fabrication technique.

Solidification of concentrated zero-valent iron slurry: A microrheology study using diffusing wave spectroscopy

Concentrated zero-valent iron (ZVI) slurries (CIS) are commonly encountered during the water treatment using ZVI, in the processes such as delivery, settling, and pumping of the ZVI slurry; about the CIS, knowledge about their rheology is critical to the operation of these processes, but little is known about this aspect so far. Herein, microrheology of the CIS of four different ZVI is studied using diffuse wave spectroscopy (DWS). Results show that the CIS of two iron nanoparticles solidify immediately after their separation from water (<3 h), with a fast growth of macroscopic viscosity and a rapid weakening of the fluidity; the CIS of the microscale ZVI (mZVI) is nearly pure viscous or liquid-like and solidifies slower than the nanoparticle CIS; CIS of the floc modified ZVI (mZVI(floc)) is viscoelastic and remains stable in rheology over an extended period up to four days. Such differences in CIS rheology are explained by the coarse surface of the nanoparticle aggregates, the smooth surface of mZVI particles, the intertwined floc coating of mZVI(floc) particles, and the corresponding disparity in surface friction between the particles or aggregates. The solidification of CIS is explained by the binding effect of the oxidation products of the ZVI-water reaction. This study provides information about CIS rheology and offers guidance for process operations in the water treatment using ZVI. This study also shows that the DWS technique is informative in characterizing CIS and the method may be equally applicable for studying other concentrated particle slurries in water treatment.

The Optimization of Avocado-Seed-Starch-Based Degradable Plastic Synthesis with a Polylactic Acid (PLA) Blend Using Response Surface Methodology (RSM).

This research improves the strength of plastic using avocado seed starch and PLA. The effect of blending avocado seed starch and PLA was optimized using the RSM approach by using two variables: water absorption and biodegradability. Mixing them using RSM gave the best result: 1.8 g of starch and 3 g of PLA. Degradable plastic has a tensile strength of 10.1 MPa, elongation at a break of 85.8%, and a Young's modulus of 190 MPa. Infrared spectroscopy showed that the plastic had a -OH bond at 3273.20 cm-1, 3502.73 cm-1, and 3647.39 cm-1, a CH2 bond at 2953.52 cm-1, 2945.30 cm-1, and 2902.87 cm-1, a C=C bond at 1631.78 cm-1, and a C-O bond at 1741.72 cm-1. The plastic decomposed in the soil. It was organic and hydrophilic. Thermal tests demonstrated that the plastic can withstand heat well, losing weight at 356.86 °C to 413.64 °C, forming crystals and plastic melts at 159.10 °C-the same as PLA. In the melt flow test, the sample melted before measurement, and was therefore not measurable-process conditions affected it. A water absorption of 5.763% and biodegradation rate of 37.988% were found when the samples were decomposed for 12 days. The starch and PLA fused in the morphology analysis to form a smooth surface. The RSM value was close to 1. The RSM gave the best process parameters.

The comparison of melt technologies based on mesoporous carriers for improved carvedilol dissolution

High-shear (HS) melt granulation and hot melt extrusion (HME) were compared as perspective melt-based technologies for preparation of amorphous solid dispersions (ASDs). ASDs were prepared using mesoporous carriers (SyloidⓇ 244FP or NeusilinⓇ US2), which were loaded with carvedilol dispersed in polymeric matrix (polyethylene glycol 6000 or SoluplusⓇ). Formulations with high carvedilol content were obtained either by HME (11 extrudates with polymer:carrier ratio 1:1) or HS granulation (6 granulates with polymer:carrier ratio 3:1).DSC and XRD analysis confirmed the absence of crystalline carvedilol for the majority of prepared ADSs, thus confirming the stabilizing effect of selected polymers and carriers over amorphous carvedilol. HME produced larger particles compared to HS melt granulation, which was in line with better flow time and Carr index of extrudates. Moreover, SEM images revealed smoother surface of ASDs obtained by HME, contributing to less obstructed flow. The rougher and more porous surface of HS granules was correlated to larger granule specific surface area, manifesting in faster carvedilol release from SyloidⓇ 244FP-based granules, as compared to their HME counterparts. Regarding dissolution, the two HS-formulations performed superior to pure crystalline carvedilol, thereby confirming the suitability of HS melt granulation for developing dosage forms with improved carvedilol dissolution.

Remineralizing effect of NSF on artificial enamel caries

IntroductionNanotechnology offers new approaches and endless opportunities for remineralizing tooth decay without being toxic or causing allergies. This study aimed to determine the effect of nanosilver fluoride (NSF) on the remineralization potential of enamel caries-like lesions compared to 5% sodium fluoride varnish in permanent teeth.MethodsFifteen teeth (molars and premolars) were gathered, cleaned, and polished using a scaler. After sectioning the teeth mesiodistally and removing the roots, the thirty specimens were subjected to a demineralized solution to induce early enamel lesions and then assigned randomly into two equal groups. The test materials were applied, and then all the specimens were subjected to a pH cycling model for 30 days. DIAGNOdent and surface roughness were investigated, and an evaluation of the enamel Ca and P weight% for Ca/P ratio calculation was done using SEM-EDX to analyze the specimens at the end of the study. The data were analyzed using an independent t-test.ResultsThe mean values for the DIAGNOdent measurements for NSF and NaF at baseline and after demineralization were not significantly different (p > 0.05). After treatment, NaF varnish showed a significantly higher mean DIAGNOdent measurement (11.8 ± 5.80) than NSF (4.7 ± 1.6). The mean surface roughness of the NaF group (1.64 ± 0.39) was much higher than NSF’s mean surface roughness (1.07 ± 0.21). Specimens treated with NSF had statistically significant smoother surfaces (p < 0.001). The NSF group had a higher mean Ca/P ratio (2.9 ± 0.35) than NaF (2.2 ± 0.11). This difference was statistically significant (p = 0.012).ConclusionThe study reveals that nano silver fluoride is a more effective treatment than sodium fluoride varnish in enhancing teeth’s clinical characteristics, particularly in terms of mineral content and surface roughness, suggesting it could be an improved strategy to prevent dental caries and maintain enamel integrity.

Scalability of API-Loaded Multifilament Yarn Production by Hot-Melt Extrusion and Evaluation of Fiber-Based Dosage Forms.

Fiber-based technologies are widely used in various industries, but their use in pharmaceuticals remains limited. While melt extrusion is a standard method for producing medical fibers such as sutures, it is rarely used for pharmaceutical fiber-based dosage forms. The EsoCap system is a notable exception, using a melt-extruded water-soluble filament as the drug release trigger mechanism. The challenge of producing drug-loaded fibers, particularly due to the use of spinning oils, and the processing of the fibers are addressed in this work using other approaches. The aim of this study was to develop processes for the production and processing of pharmaceutical fibers for targeted drug delivery. Fibers loaded with polyvinyl alcohol and fluorescein sodium as a model drug were successfully prepared by a continuous melt extrusion process and directly spun. These fibers exhibited uniform surface smoothness and consistent tensile strength. In addition, the fibers were further processed into tubular dosage forms using a modified knitting machine and demonstrated rapid drug release in a flow cell.

Physicochemical Characteristics of Residual Carbon and Inorganic Minerals in Coal Gasification Fine Slag.

Investigating the physicochemical properties and embedding forms of residual carbon (RC) and slag particles (SPs) in coal gasification fine slag (FS) is the basis for achieving its separation and utilization. An in-depth understanding of their compositional characteristics allows for targeted treatment and utilization programs for different components. In this work, the physicochemical properties and embedding forms of RC and SPs in FS were systematically investigated. An innovative calculation method is proposed to determine the mass fraction of dispersed carbon particles, dispersed mineral-rich particles, and carbon-ash combined particles by using a high-temperature heating stage coupled with an optical microscope. The unburned RC with a rough, loose surface and a well-developed pore structure acted as a framework in which the smaller spherical SPs with a smooth surface were embedded. In addition, the sieving pretreatment process facilitated the enrichment of the RC. Moreover, the RC content showed significant dependencies according to the FS particle size. For FS with a particle size of 0.075-0.150 mm, the mass proportions of dispersed carbon, ash particles, and the carbon-ash combination were 15.19%, 38.72%, and 46.09%, respectively. These findings provide basic data and reliable technical support for the subsequent carbon and ash separation process and the comprehensive utilization of coal gasification slag.

Dolosigranulum savutiense sp. nov., isolated from human upper respiratory samples collected in Botswana.

Four strains (MSK211, MSK294T, MSK312, MSK433) of a novel Dolosigranulum species were cultured from nasopharyngeal swabs collected from mother-infant dyads in southern Botswana. These strains grew optimally on tryptic soy agar with 5% sheep blood solid medium and in fastidious bacteria broth. Colonies on tryptic soy agar with 5% sheep blood agar appeared grey or white with a flat, smooth surface and variable alpha haemolysis. Cells were Gram-positive, non-spore-forming, non-motile cocci that lacked catalase or oxidase activity. Major fatty acids were C16 : 0 (palmitic acid), C18 : 1 ω9c (oleic acid), and C18 : 0 (stearic acid). Analyses of 16S rRNA gene sequences identified these strains as belonging to the genus Dolosigranulum (family Carnobacteriaceae), which currently contains only a single validly published species (Dolosigranulum pigrum). Whole-genome sequencing revealed that the genomes of these strains are 1.98-2.07 Mbp in size and have a G+C content of 39.6-39.9 mol%. Comparisons of these genomes to publicly available genomes of D. pigrum yielded average nucleotide identities and in silico DNA-DNA hybridization values of 92.3-92.9% and 49.1-51.4%, respectively. These results indicate that these strains represent a novel species of Dolosigranulum, for which we propose the name Dolosigranulum savutiense sp. nov., with the type strain MSK294T (=DSM 117171T=JCM 36673T).

Encapsulation of resveratrol in alginate microcapsules using internal gelation technique: Fabrication, characterization and release kinetics

Resveratrol (RES) is a proven anticancer, antioxidant, anti-inflammatory, and cardioprotective compound. However, low bioavailability, poor water solubility, and sensitivity to UV light and heat limit RES's use in food applications. In this study, we aim to protect RES by encapsulating it in sodium alginate (NaAlg) matrix using internal gelation, followed by drying the moist microencapsulates using spray and freeze-drying techniques. The spray-dried microencapsulates exhibited a smaller mean diameter (5.57 ± 2.40 μm), higher encapsulation efficiency (91.32 ± 1.98%), and higher ζ-potential (−61.9 ± 2.33 mV) compared to freeze-dried microencapsulates. SEM images revealed the smooth and spherical surface of the spray-dried microencapsulates, while the freeze-dried samples exhibited irregular shapes and porous textures. FTIR results showed polyelectrolyte interactions between NaAlg, RES, and CaCO3. XRD and DSC results confirmed the incorporation of RES in the NaAlg matrix. Spray-dried microencapsulates demonstrate the highest RES retention of 80.89 ± 0.70% and 78.59 ± 0.27% after 4 h of UV light and thermal treatments, respectively. In vitro release studies showed that spray-dried microencapsulates demonstrate a delayed gastric release compared to freeze-dried microencapsulates. The release mechanism of RES from the microencapsulates was effectively described by the Shalin-Peppas model.

Influence of titanium surface roughness on a nanoscale on the zeta potential and platelet adhesion.

Thromboembolic complications still arise on blood contacting surfaces. Surface charge and topography influence the subsequent deposition of proteins and platelets, potentially leading to thrombi. Research showed a correlation of surface charge and nanoscale roughness, and a negative surface charge as well as a smooth surface finish are associated with lower thrombogenicity. The aim of this study was to compare the platelet adhesion on titanium with different nanoscale roughnesses and to examine if those roughness variations caused a change in surface charge. Titanium samples were polished and roughened to four different nanoscale roughness levels. Platelet adhesion (covered surface area (CSA), N = 8) was tested in flow chambers with human whole blood using fluorescence imaging. ζ-potential was measured over a broad range of pH-values and interpolated to obtain the ζ-potential for pHBlood (7.4). Platelet adhesion tests were evaluated in terms of p-values and the Wilcoxon test effect size and the trend of the ζ-potential at pHBlood and the CSA was compared. Ra-values ranged between 35 (polished) and 156 nm. Regarding platelet adhesion, the polished sample showed the lowest mean CSA with a medium or strong effect size compared to the roughened samples. The interpolated ζ-potentials for pHBlood follow a similar trend as the CSA, with the lowest ζ-potential measured for the polished surface. These findings suggest that the decreasing ζ-potential due to lower nanoscale roughness might be an additional explanation for the improved hemocompatibility besides the smoother topography.