Static Contact Angle Measurements Research Articles

Fabrication of 3D micropatterned hydrophobic surfaces by fused filament fabrication printing technology

AbstractIn recent years, the interest in structured hydrophobic surfaces has considerably grown, finding applications in many industrial fields, including aerospace, automotive, and biomedical. Three‐dimensional (3D) printing technology is a simple, rapid and economic process to fabricate structured surfaces based on neat polymers and composite materials, allowing working with a wide variety of plastic materials. The manufactured surfaces show a roughness depending on the printing design and the printing resolution: this characteristic is ideal to achieve superhydrophobic properties. Furthermore, patterned surface structures can be printed by Fused Filament Fabrication (FFF), so increasing the hydrophobic character of the samples; indeed, micro and nano surface structures are required to make a hydrophobic surface.In this study, 3D micro‐patterned textures of pillars were printed by FFF using polylactide (PLA) and polypropilene (PP) as polymer filaments and PLA/carbon nanotubes (PLA/CNT) and PP/carbon fibers (PP/CF) as composite filaments. Morphologies of printed specimens were analyzed by optical microscopy and scanning electron microscopy (SEM). Good correspondence was found between pillars dimensions and edge‐edge pillars distance of CAD model and composites 3D printed samples. Their wettability was evaluated by static contact angle measurements. Results clearly show a significant increase of water contact angle values up to 50% in all micropatterned samples with respect to flat surfaces. This improvement was achieved by surface microstructuring without the use of nanoparticles and/or chemical treatment.This article is protected by copyright. All rights reserved.

Phenyl-Substituted Cage Silsesquioxane-Based Star-Shaped Giant Molecular Clusters: Synthesis, Properties, and Surface Segregation Behavior.

The crystallinity, solubility, and physical properties of polyhedral oligomeric silsesquioxane (POSS) compounds are highly dependent on their organic substituents. We previously synthesized a series of isobutyl-substituted star-shaped POSS derivatives with aliphatic chain linkers of different length. In this study, we prepared C3- and C6-linked phenyl-substituted star-shaped POSS derivatives (3Ph-C3 and 3Ph-C6) by the hydrosilylation of heptaphenylallyl- and hexenyl-POSS (1a and 1b) and octadimethylsiloxy-Q8-silsesquioxane (Q8M8H) (2), respectively, and their properties were compared with those of the corresponding isobutyl-substituted derivatives (5iBu-C3 and 5iBu-C6). Although 3Ph-C6 was only soluble in chloroform and insoluble in tetrahydrofuran (THF) and toluene, 3Ph-C3 was soluble even in THF and toluene, suggesting that the shorter linkers of the derivative afford a wider range of solvents for dissolution. Differential scanning calorimetry analysis showed that 3Ph-C3 exhibited a baseline shift at 190 °C and an endothermic peak at 316 °C. However, no clear baseline shift was observed for 3Ph-C6. Thermogravimetric analysis showed that the shorter linker in the phenyl-substituted star-shaped POSS derivative significantly increased the decomposition temperature compared with the longer linker. The annealed cast film of 3Ph-C3 at 340 °C above its melting temperature formed a transparent film even after cooling to room temperature. However, an opaque whitish film was formed in the case of 3Ph-C6. Poly(methyl methacrylate) (PMMA) films containing 2 wt % 3Ph-C3 and 3Ph-C6 were prepared by casting their chloroform solutions onto glass substrates overnight at room temperature. The static water contact angle measurements and XPS analysis for the castings film containing 3Ph-C3 and 3Ph-C6 suggested that degree of the segregation amount of 3Ph-C3 was larger than that of 3Ph-C6. The shorter linker length in the phenyl-substituted star-shaped POSS derivative, 3Ph-C3, with its greater predicted solubility in PMMA, exhibited entropy-driven surface segregation.

Static contact angle, interfacial tension, and column height measurements for underground hydrogen storage

Geological porous media are key for large-scale hydrogen (H2) storage and production, where fluid interactions at interfaces and within rock formations are vital for effective gas containment. Although advancements have been achieved in comprehending structural trapping for estimating column height (CH), additional insights are required regarding how pore size impacts this estimation. Currently, CH estimates often consider seal rock potential, without including the capillary contribution from reservoir rock pore for structural trapping capacity assessment. This study measures the static contact angle (CA) on Wolfcamp (WC) Shale and interfacial tension (IFT) under modified drainage and imbibition conditions at temperatures of 30 and 50°C, pressures ranging from 500 to 3000 psia, and a salinity of 10 wt% sodium chloride. Subsequently, the static gas CH was calculated, accounting for contributions from the caprock pores alone and both the caprock and reservoir, to assess the structural sealing capacity of the caprock layer. The experimental procedures are comprehensively detailed in this paper. The outcome indicates that the static CA after drainage for H2)/brine/WC shale rises with pressure as the static CA after imbibition decreases. Both CAs decrease with increasing temperatures. For H2/brine systems, both drainage and imbibition IFTs decline with increasing pressure and temperature. Calculated CHs reveal that lower CAs substantially impact the gas trapping capacity beneath the caprock. In summary, this study highlights the preference for the drainage method in measuring IFT and CA to evaluate the potential structural trapping capacity of injected gas by the overlying caprock.

Antibacterial Zirconia Surfaces from Organocatalyzed Atom-Transfer Radical Polymerization.

Antibacterial coatings are becoming increasingly attractive for application in the field of biomaterials. In this framework, we developed polymer coating zirconia with antibacterial activity using the "grafting from" methodology. First, 1-(4-vinylbenzyl)-3-butylimidazolium chloride monomer was synthesized. Then, the surface modification of zirconia substrates was performed with this monomer via surface-initiated photo atom transfer radical polymerization for antibacterial activity. X-ray photoelectron spectroscopy, ellipsometry, static contact angle measurements, and an atomic force microscope were used to characterize the films for each step of the surface modification. The results revealed that cationic polymers could be successfully deposited on the zirconia surfaces, and the thickness of the grafted layer steadily increased with polymerization time. Finally, the antibacterial adhesion test was used to evaluate the antibacterial activity of the modified zirconia substrates, and we successfully showed the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa strains.

Bioinspired Superhydrophobic Nanocoating Based on Polydopamine and Nanodiamonds to Mitigate Bacterial Attachment to Polyvinyl Chloride Surfaces in Food Industry Environments.

Polyvinyl chloride (PVC) is commonly utilized as a food-contact surface by the food industry for processing and storage purposes due to its durability, ease of fabrication, and cost-effectiveness. Herein, we report a composite coating for the superhydrophobization of PVC without the use of polyfluoroalkyl chemistry. This coating rendered the PVC superhydrophobic, exhibiting a static water contact angle of 151.9 ± 0.7° and a contact angle hysteresis of only 3.1 ± 1.0°. The structure of this composite coating, consisting of polydopamine, nanodiamonds, and an alkyl silane, was investigated by utilizing both scanning electron microscopy and atomic force microscopy. Surface chemistry was probed using attenuated total reflectance-Fourier transform infrared, and the surface wetting behavior was thoroughly characterized using both static and dynamic water contact angle measurements. It was demonstrated that the superhydrophobic PVC was cleanable using a food-grade surfactant, becoming wet in contact with high concentration surfactant solutions, but regaining its nonwetting property upon rinsing with water. It was demonstrated that the coating produced a 2.1 ± 0.1 log10 reduction (99.2%) in the number of Escherichia coli O157:H7 cells and a 2.2 ± 0.1 log10 reduction (99.3%) in the number of Salmonella enterica Typhimurium cells that were able to adsorb onto PVC surfaces over a 24 h period. The use of this fluorine-free superhydrophobic coating on PVC equipment, such as conveyor belts within food production facilities, may help to mitigate bacterial cross-contamination and curb the spread of foodborne illnesses.

Gravimetric and electrochemical evaluation of environmentally novel nanopyrazole derivatives for 304 SS in acidic solution: AFM, SEM/EDX, contact angle, and DFT/MDs simulations

Influence of two novel corrosion inhibitors of bis(chromeno[4,3‐c]pyrazol‐4‐oxo‐2‐yl)phosphineoxide (CPO) and bis(4‐formyl‐3‐phenyl‐1H‐pyrazol‐1‐yl)phosphineoxide (FPO) on the localized corrosion protection of 304 stainless steel (304 SS) in a 1.0 M HCl solution was investigated at different concentrations (10−13−10−5 M) and at different temperatures (298–343 K). Weight loss and electrochemical measurements indicated that the pyrazole derivatives are efficient inhibitors for corrosion of 304 SS, and the inhibition efficiency was increased with inhibitor concentrations up to 73.18 and 98.50 % for CPO and FPO, respectively. Langmuir adsorption isotherm was found to be the more fitted model for the adsorption process description with mixed adsorption mechanisms. UV–visible and XRD measurements showed the formation of a protective film formed by corrosion inhibitors. The scanning electron microscope (SEM) images, energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and static contact angle measurement corroborated the protection provided by CPO and FPO inhibitors on the surface of 304 SS immersed in a 1.0 M HCl solution. FPO exhibits antibacterial activity, and CPO has antifungal activity. The relationships between the corrosion protection performance of the pyrazole derivatives, their structural properties, and the adsorption type were determined by density functional theory (DFT), natural bond orbital (NBO), and molecular dynamics (MD), which confirmed that FPO has a higher corrosion protection efficiency than CPO. The theoretical parameters were in good agreement with the experimental results.

Effect of Camera Parallax Angle on the Accuracy of Static Contact Angle Measurements.

Measuring the contact angle at the solid/liquid/vapor triple point in sessile drop experiments is one of the most popular and simple ways to quantify the wettability of surfaces and determine the surface free energy. Despite decades of technical advancements in contact angle measurements, which allowed for improving the precision of sessile drop measurements below ±1°, an often overlooked source of experimental error in these measurements originates from the camera's parallax angle (PA) - the angle between the camera optical axis and the sample stage surface. Here, we quantified the systematic errors in the measurement of contact angles due to the acquisition of drop images at finite PA values by simulating sessile drop experiments in which synthetic drops were created using the Young-Laplace equation. The absolute contact angle error induced by imaging drops at nonzero PAs was found to increase as the true contact angle (TCA) deviates from 90° and resulted in an overestimation (underestimation) of the contact angle for drops having TCAs lower (higher) than 90°. The computed absolute contact angle error reaches values as high as -20° (+12.2°) for drops having a TCA of 175° (5°) when imaged with a PA of 10°, thus indicating the importance of considering the PA when accurately quantifying contact angles in sessile drop experiments. The shape and, by extension, volume of the sessile drop was also found to affect the magnitude of the absolute contact angle error as sessile drops with higher apex curvatures exhibited lower absolute error than those with lower curvatures at any given PA. The outcomes of this work provide guidelines for minimizing systematic errors in sessile drop measurements due to the collection of drop images at nonzero PAs.

Hydrothermally synthetized WO3 coated stainless steel mesh for oil–water separation purposes

To separate oil–water mixtures especially in oil field operations, new energy-efficient methods are urgently required. Conventional separation techniques using demulsifiers for separation of oil–water mixtures or even use of membranes usually suffered from high cost and energy consumption, composition dependency of demulsifiers and fouling or inability of a single membrane to separate all types of oil–water mixtures. This research aimed to synthesize tungsten oxide-coated stainless steel mesh using the hydrothermal method, with a focus on evaluating its effectiveness in oil–water separation. The coating procedure was carried out using hydrothermal techniques, with an emphasis on investigating the impact of precursor concentration, pH levels, reaction temperature and duration, on the separation efficiency of the optimal coating solution. The hydrothermally coated stainless steel mesh was created within a polytetrafluoroethylene reaction vessel, submerged in a 150 ml aqueous solution containing 0.0094 mol of sodium tungstate di-hydrate at pH 3.0, achieved through the addition of hydrochloric acid. Additionally, 1 g of oxalic acid, acting as a chelating agent, was introduced. Subsequently, the mesh underwent a 4 h reaction at 220 °C and was subsequently annealed for 30 min in a 350 °C furnace. Remarkably, the resultant mesh exhibited an exceptional water separation flux of 9870 ± 15 L/hr/m2 when exposed to 1:1 v/v oil–water mixtures. This performance significantly outperformed previous filters designed for similar oil–water separation tasks. The mesh efficiently facilitated the passage of water through the oil–water mixture, achieving an efficiency rate exceeding 98 ± 1%. To gauge its wetting behavior, the hydrophilic/underwater oleophobic filter underwent static contact angle measurements. The filter's wetting mechanism was primarily attributed to its hierarchical surface structure, which enhanced surface hydrophilicity and roughness. Analytical techniques such as XRD, FTIR, and FE-SEM were employed to scrutinize the fabricated filter's composition. These analyses confirmed the successful creation of a nanostructured WO3 coating on both sides of the stainless steel mesh. Moreover, the utilization of commercially available chemicals and straightforward fabrication techniques underscores the promising potential of this approach for large-scale applications.

Host-Guest Mechanism via Induced Fit Fullerene Complexation in Porphin Receptor to Probe Salivary Alpha-Amylase in Dental Caries for Clinical Applications.

Salivary α-amylase is the most abundant protein of human saliva that potentially binds to streptococcus and other bacteria via specific surface-exposed α-amylase-binding proteins and plays a significant role in caries development. The detection of α-amylase in saliva can be used as a bioindicator of caries development. Herein, a facile strategy has been applied, tailoring the photochemical properties of 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine (TPPOH) and the fullerene C60 complex. The fluorescence emission of TPPOH is quenched by starch-coated fullerene C60 via charge-transfer effects, as determined by UV absorption and fluorescence spectroscopic studies. The starch-coated C60 has been thoroughly characterized via Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), optical microscopy, thermal gravimetric analysis (TGA), static water contact angle measurements, and zeta potential measurements. The analytical response of the assay showed a linear fluorescent response in α-amylase concentrations ranging from 0.001-0.1 Units/mL, with an LOD of 0.001 Units/mL. The applicability of the method was tested using artificial saliva with quantitative recoveries in the range 95-100%. The practicability of the procedure was verified by inspecting saliva samples of real clinical samples covering all age groups. We believe that the proposed method can serve as an alternative analytical method for caries detection and risk assessment that would also minimize the cost of professional preventive measures and treatments.

A highly sensitive and selective impedimetric sensor for the determination of oxytetracycline based on a new polyamine functionalized calix [4] arene

The antibiotic oxytetracycline (OTC), from the tetracycline family of drugs, is generally used to enhance growth as well as to prevent and cure harmful microorganisms in animals and aquaculture. However, improper OTC use exposes people to trace amounts of antibiotics in the food chain, increasing their risk of health problems. For the first time, a new calix [4] arene functionalized at the upper rim by protected ethylenediamine groups has been successfully synthesized and fully characterized by using elemental analysis 1H NMR, 13C NMR, and HRMS. Moreover, indium tin oxide electrode (ITO) modified with the calix [4] arene derivative (EDCA [4]) was successfully prepared using a simple drop-cost method. EDCA [4] film was characterized by static contact angle measurement, cyclic voltammetry measurement, electrochemical impedance spectroscopy, and microscopic surface imaging (SEM). Electrochemical impedance spectroscopy (SIE) measurement showed that the EDCA [4]/ITO exhibited high molecular recognition and consequently displayed a good impedimetric response toward oxytetracycline (OTC).The developed sensor exhibited a wide linear concentration range of 10−10M to 10−5M and a lower detection limit of 2.3 10−11 M. Also, the presented sensor has demonstrated great selectivity and reproducibility, and the designed electrochemical platform was successfully used for detecting trace oxytetracycline in spiked milk samples.

Preparation of hydrophobic layered double hydroxide-based composite pigments via octyltriethoxysilane surface modification for cosmetic applications.

Pigments play a pivotal role in the cosmetic industry, in which the development of pigments with concurrent color diversity, hydrophobicity, biocompatibility and photostability remains a great challenge. Herein, we report organic-inorganic composite pigments synthesized via a combination of organic dye anions (Ponceau SX and acid green (AG)), layered double hydroxides (LDHs) and octyltriethoxysilane (OTEOS) (denoted as O/Dye-LDHs: O/SX-LDHs and O/AG-LDHs).The prepared composite pigments were characterized via a comprehensive investigation based on X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS-mapping), Fourier transform infrared (FT-IR) spectroscopy, CIE 1976 L*a*b* color scales, static contact angle measurement and HET-CAM assay. The results confirm the successful intercalation of organic dye anions into the interlayer region of LDHs via host-guest interactions and the surface modification of OTEOS on the layer surface, forming a new kind of hydrophobic organic-inorganic composite pigment with a sandwich structure. LDH layer protection and OTEOS coating play crucial roles in the high photostability, good hydrophobicity and satisfactory biocompatibility of pigments. In addition, O/Dye-LDHs exhibit rich color and color adjustability. Impressively, we applied mixture composite pigments with different O/SX-LDH-to-O/AG-LDH ratios to formulate an eye shadow cream, which present a series of popular and natural colours with water resistance to enhance one's attractiveness and appearance. This work provides a promising strategy for the design of safe and efficient composite pigments, demonstrating their potential application in the field of makeup.

Development of hydrophobic coating on 3D printed ABS samples and surface characterization

Manufacturers are increasingly substituting additive manufacturing for conventional manufacturing methods due to their ability to produce complex shapes. Polymer-based filament materials can be printed efficiently and inexpensively with fused deposition modeling. Coatings tend to augment the appearance of 3D printed objects as well as protect them from environmental influences. It is imperative to realize the physical and chemical properties of polymeric material like Acrylonitrile Butadiene Styrene (ABS) surfaces so as to design an optimal surface system. This work relates to the development of surface coatings on 3D-printed ABS parts. L9 orthogonal array was used with three 2 level factors for printing the samples. Specifically, the research compares surface characteristics of 3D-printed uncoated and coated ABS specimens. An aqueous solution containing Tricalcium phosphate and Chitin clear solutions in a 70:30 ratio was applied through immersion technique to create hydrophobic coatings. The coated and uncoated samples were characterized by employing various characterization tests, including dimensional accuracy (DA), surface roughness (SR), water contact angle (WCA), absorbency tests, scanning electron microscopy on fabricated parts. Assessment of wettability of 3D printed samples and impact of coating was accomplished via static contact angle measurements. In order to assess DA and SR before and after coating, digital vernier calipers were used in conjunction with a profilometer. In accordance with ASTM D570-98, water absorption tests were conducted for specified time. Results of investigation post coating showed no variation in dimensional accuracy, reduced SR and increased in WCA by ≥ 100 ̊. A reduction in water retention was observed after coating based on water absorption tests.

Ethyl cellulose–graphene oxide composite dense membranes: Kinetic and thermodynamic studies of dye adsorption

Graphene oxide (GO) is extensively used in dye adsorption from wastewater. Polymer–GO composite membranes exhibits improved surface wettability and dye adsorption capacity. In this study, ethyl cellulose (EC)–GO nanocomposite dense membranes (EG membranes) are prepared by the solvent casting method. The morphology and physicochemical properties of the developed nanocomposite membranes are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction studies, thermogravimetric analysis, static contact angle measurements, and UV–visible spectroscopy. The derivative thermogravimetry curves indicate the complete degradation of the composites below [Formula: see text]C. The results confirm the homogeneous dispersion of GO in the EC matrix. The addition of GO to the EC matrix leads to a remarkable increase in surface wettability which decreases the contact angle to [Formula: see text] for the membrane with a 0.7% addition of GO. The prepared membranes are used for the separation of methylene blue from water. The adsorption properties of the prepared membranes are found to be varying in accordance with the contact angle values. The equilibrium data fit well for the Langmuir model and the adsorption follows pseudo-second-order kinetics.

Projection Micro-Stereolithography to Manufacture a Biocompatible Micro-Optofluidic Device for Cell Concentration Monitoring.

In this work, a 3D printed biocompatible micro-optofluidic (MoF) device for two-phase flow monitoring is presented. Both an air-water bi-phase flow and a two-phase mixture composed of micrometric cells suspended on a liquid solution were successfully controlled and monitored through its use. To manufacture the MoF device, a highly innovative microprecision 3D printing technique was used named Projection Microstereolithography (PμSL) in combination with the use of a novel 3D printable photocurable resin suitable for biological and biomedical applications. The concentration monitoring of biological fluids relies on the absorption phenomenon. More precisely, the nature of the transmission of the light strictly depends on the cell concentration: the higher the cell concentration, the lower the optical acquired signal. To achieve this, the microfluidic T-junction device was designed with two micrometric slots for the optical fibers' insertion, needed to acquire the light signal. In fact, both the micro-optical and the microfluidic components were integrated within the developed device. To assess the suitability of the selected biocompatible transparent resin for optical detection relying on the selected working principle (absorption phenomenon), a comparison between a two-phase flow process detected inside a previously fully characterized micro-optofluidic device made of a nonbiocompatible high-performance resin (HTL resin) and the same made of the biocompatible one (BIO resin) was carried out. In this way, it was possible to highlight the main differences between the two different resin grades, which were further justified with proper chemical analysis of the used resins and their hydrophilic/hydrophobic nature via static water contact angle measurements. A wide experimental campaign was performed for the biocompatible device manufactured through the PμSL technique in different operative conditions, i.e., different concentrations of eukaryotic yeast cells of Saccharomyces cerevisiae (with a diameter of 5 μm) suspended on a PBS (phosphate-buffered saline) solution. The performed analyses revealed that the selected photocurable transparent biocompatible resin for the manufactured device can be used for cell concentration monitoring by using ad hoc 3D printed micro-optofluidic devices. In fact, by means of an optical detection system and using the optimized operating conditions, i.e., the optimal values of the flow rate FR=0.1 mL/min and laser input power P∈{1,3} mW, we were able to discriminate between biological fluids with different concentrations of suspended cells with a robust working ability R2=0.9874 and Radj2=0.9811.

Impact of high substrate temperature on pulsed laser deposited ZnO pillars: A technological route to investigate the structural, optical and superhydrophilic properties

The structural, optical, and superhydrophilic properties of zinc oxide (ZnO) pillars are reported by pulsed laser deposition (PLD) technique at a high substrate temperature of 700 °C. The X-ray diffraction (XRD) analysis reveals that the increased crystallite size in ZnO-700 (98.47 nm) plays an important role in promoting superhydrophilic behaviour than ADZnO-RT (57.19 nm). The root-mean-square surface roughness (Rr.m.s) from scanning probe microscope (SPM) analysis demonstrates the significant enhancement in ZnO-700 surfaces. The ZnO-700 based samples show improved light absorption in the ultra-violet (UV) and visible light absorption which can boost photocatalytic activity. The photoluminescence (PL) analysis shows the highest (zinc) Zn interstitial (Zni) and lowest oxygen vacancy (OV) concentration in ZnO-700. A static contact angle (CA) measurement was performed, where ZnO-700 sample displays a smaller static CA (98.60°) compared to ADZnO-RT (101.90°), indicating more superhydrophilic nature. The ZnO-700 based sample had a better sliding angle (α) of 61.65°, a maximum frictional force (Fmax) of 1.76 μN, a corresponding work of adhesion (Wadhesion) 61.01 mN/m, and a wettability conversion rate (WCR) of 7.20 × 10−5°−1/min indicating fast sliding phenomena and better superhydrophilic transition. The superhydrophilic properties of ZnO-700 make it a valuable asset for smart surfaces and microfluidic devices application.

Numerical and Experimental Investigation of Aerodynamic Characteristics of Morphing Trailing Edge Wings in The Application of MAV

In the past few years, FDM basedpolymer3D printing process has flourished mainly with ABS filaments as a thermoplastic source. Food packing, medical, marine and agriculture industries employdevices and other usable items made of polymers. Utilizing layered fabrication components in these areascompelthem to have self-cleansing, anti-freezing and corrosion resistant surfaces. It is generally complex and expensive to prepare hydrophobic coatings. The present work is related to the development of a surface coating on 3D printed ABS specimens with the mentioned properties. 3D printed specimens were fabricated using Flash Forge 3D printer without any modifications, and the hydrophobic coatings were achieved by dip coating process using Tricalcium phosphate-chitin solutions with a ratio of 70:30. Static contact angle measurement was employedin gaging wettability impact on dip coated 3D printed specimens. By using digital vernier calipers and profilometer (SJ410), dimensional accuracy and surface roughness were assessed pre and post-coating. According to ASTM D570-98, water absorption tests were conducted at different time intervals. Results of the experiment showed that the hydrophobic solutions had been successfully synthesized. The maximum contact angle was achieved for solution 1(4g of tricalcium phosphate solution with 0.3g chitin solution) i.e., 109.3°. Improvement in the textureof 3D printed ABS surfaceswasobserved after dip coating. Dip-coated 3D printed ABS specimens exhibited minimal absorption based on their weight gain per area.

Investigating The Surface Characteristics of Dip Coated 3D Printed ABS Specimens

In the past few years, FDM basedpolymer 3D printing process has flourished mainly with ABS filaments as a thermoplastic source. Food packing, medical, marine and agriculture industries employdevices and other usable items made of polymers. Utilizing layered fabrication components in these areascompelthem to have self-cleansing, anti-freezing and corrosion resistant surfaces. It is generally complex and expensive to prepare hydrophobic coatings.The present work is related to the development of a surface coating on 3D printed ABS specimens with the mentioned properties. 3D printed specimens were fabricated using Flash Forge 3D printer without any modifications, and the hydrophobic coatings were achieved by dip coating process using Tricalcium phosphate-chitin solutions with a ratio of 70:30. Static contact angle measurement was employedin gaging wettability impact on dip coated 3D printed specimens. By using digital vernier calipers and profilometer (SJ410), dimensional accuracy and surface roughness were assessed pre and post-coating. According to ASTM D570-98, water absorption tests were conducted at different time intervals. Results of the experiment showed that the hydrophobic solutions had been successfully synthesized. The maximum contact angle was achieved for solution 1(4g of tricalcium phosphate solution with 0.3g chitin solution) i.e., 109.3°. Improvement in the textureof 3D printed ABS surfaceswas observed after dip coating. Dip-coated 3D printed ABS specimens exhibited minimal absorption based on their weight gain per area.

Wettability Effects of Curved Superhydrophobic Surfaces on Drag Reduction in Taylor–Couette Flows of Water and Oil

Abstract This study examines the effects of surface wettability on the drag-reducing performance of three hydrophobic coatings, namely, flouropel coating (FPC-800M), superhydrophobic binary coating (SHBC), and ultra-ever dry (UED)—when applied to curved aluminum surfaces. The wettability and flow characteristics were characterized using three liquids of different viscosities: de-ionized water and silicone oils of 5 and 10 cSt. Static and dynamic contact angles on the surfaces were measured, and the drag reduction was evaluated using a Taylor–Couette flow cell in a rheometer. The static contact angle (SCA) measurements indicated that the coated surfaces were superhydrophobic for water, with a maximum static contact angle of 158 deg, but oleophilic for the 10 cSt silicone oil, with a static contact angle of 13 deg. The rheometer measurements using water showed a maximum drag reduction of 18% for the UED-coated surfaces. Interestingly, the oleophilic surfaces (which have low SCA) showed a maximum drag reduction of 6% and 7% in the silicone oils. The observed drag reduction is due to an increase in the plastron thickness, which is caused by an increase in the Reynolds number and dynamic pressure coupled with a decrease in the static pressure normal to the superhydrophobic wall.

Enhanced antibacterial efficacy against antibiotic-resistant bacteria via nitric oxide-releasing ampicillin polymer substrates

The emergence of antibiotic-resistant bacteria poses a pressing threat to global health and is a leading cause of healthcare-related morbidity and mortality. Herein, we report the fabrication of medical-grade polymers incorporated with a dual-action S-nitroso-N-acetylpenicillamine-functionalized ampicillin (SNAPicillin) conjugated molecule through a solvent evaporation process. The resulting SNAPicillin-incorporated polymer materials act as broad-spectrum antibacterial surfaces that improve the administration efficacy of conventional antibiotics through the targeted release of both nitric oxide and ampicillin. The polymer surfaces were characterized by scanning electron microscopy and static contact angle measurements. The nitric oxide (NO) release profile and diffusion of SNAPicillin from polymers were quantified using a chemiluminescence-based nitric oxide analyzer (NOA) and ultraviolet–visible (UV–vis) spectroscopy. As a result, the films had up to 2.96 × 10−7 mol cm−2 of total NO released within 24 hr. In addition, >79 % of the SNAPicillin reservoir was preserved in the polymers after 24 hr of incubation in the physiological environment, indicating their longer-term NO release ability and therapeutic window for antibacterial effects. The SNAPicillin-incorporated polymers reduced the viability of adhered bacteria in culture, with >95 % reduction found against clinically relevant strains of Staphylococcus aureus (S. aureus). Furthermore, SNAPicillin-modified surfaces did not elicit a cytotoxic effect toward 3T3 mouse fibroblast cells, supporting the material's biocompatibility in vitro. These results indicate that the complementary effects of NO-release and ampicillin in SNAPicillin-eluting polymers can enhance the properties of commonly infected medical device surfaces for antibacterial purposes.

An innovative and universal dual-signal ratiometric spectro-electrochemical imprinted sensor design for sandwich type detection of anticancer-drug, gemcitabine, in serum samples; cross validation via computational modeling

An innovative and universal imprinted sensor design for sandwich type detection of gemcitabine (GMT) in human serum samples is described. GMT is widely used in the treatment of different tumors, such as lung, ovarian, pancreatic, and breast cancer. The serum albumin-drug interaction was translated to design a multifunctional, ratiometric and dual mode silver nanoparticle based probe (BSA-Ag nanoprobe), as a read out system. Subsequently, polypyrrol imprinted drug receptor sites was engineered to selectively capture the GMT on the transducer surface. The GMT was sandwiched between imprinted receptor surface and BSA-Ag nanoprobe to generate the spectro-electrochemical signals. The formation of nanoprobe was confirmed through various characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, micro-Raman spectroscopy, Dynamic light scattering (DLS), and UV–Visible (UV–Vis) analysis, while each step of sensor fabrication was characterized via field emission scanning electron microscope (FE-SEM), Static water Contact angle measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Different variable parameters were optimized to improve the analytical performance of the sensor design. Under optimal conditions, spectro-electrochemical sensor permitted linear ranges between 1 and 200 μmol L−1 and 0.5–200 μmol L−1, with limits of detection (LOD) of 0.4 μmol L−1 and 0.15 μmol L−1 respectively. Furthermore, the designed sensor successfully differentiated the serum samples of lung cancer patients and healthy volunteers. The obtained results were validated with standard Liquid chromatography-mass spectrometry (LC/MS) analysis of the patients and healthy volunteer's serum samples. Lastly, density functional theory (DFT) and molecular docking calculations revealed the enhanced GMT binding capability of molecularly imprinted polypyrrole and molecular level interaction between the GMT and BSA, to validate the sandwich sensor design.