Adhesion Experiments Research Articles

Freezing-induced chemical crosslinking to fabricate nanocellulose-based cryogels for efficient bilirubin removal

Construction of robust polysaccharide-based cryogels that can efficiently adsorb bilirubin is of great significance in blood purification field. However, the crosslinking of polysaccharides usually occurs before the formation of enough large ice crystals, which leads to the weak mechanical strength and relatively small pores. Herein, a novel approach is presented to fabricate microfibrillated cellulose (MFC) cryogels by using freezing-induced Michael addition reaction at −12 °C. Due to the extrusion by ice crystals and cryo-concentrated pH increase during the cryogelation process, the chemical crosslinking between bis(vinylsulphonyl)methane (BVSM) cross-linker and close contact MFCs was activated. The obtained MFC cryogels exhibit excellent mechanical strength and outstanding chemical stability under harsh conditions. Subsequently, the MFC cryogels were decorated with polyethyleneimine (PEI), bestowing them with the capability of adsorbing bilirubin. Furthermore, the biocompatibility of the resulting PEI-MFC cryogel was investigated by acute hemolysis test, MTT assay, blood coagulation experiment, along with the adhesion experiment of platelets and red blood cells, demonstrating good cytocompatibility and hemocompatibility. Finally, the adsorption performances of PEI-MFC cryogels for bilirubin in PBS and biological solution were evaluated. The PEI-MFC cryogel can efficiently adsorb bilirubin from 40.0 g L−1 bovine serum albumin solution, with a record-high adsorption capacity of 351.49 mg g−1. More importantly, the PEI-MFC cryogel could also maintain high dynamic adsorption efficiency in self-made hemoperfusion devices. This facile approach provides a new avenue to develop cellulose-based high-performance hemoperfusion adsorbent for the removal of bilirubin, showing a great promise for the translational therapy of hyperbilirubinemia.

Novel Insight of Transcription Factor PtrA on Pathogenicity and Carbapenems Resistance in Pseudomonas aeruginosa.

IntroductionGlobally, Pseudomonas aeruginosa (PA) is emerging as a predominant nosocomial pathogen that often induces aggressive and even deadly infections. Pseudomonas type III repressor A (PtrA) can be activated specifically by copper ions and interacts with type-III transcriptional activator ExsA. This study aims to provide insight into the PtrA-mediated regulation of the pathogenicity and antibiotics resistance of PA.Methods and ResultsThe results of transcriptome sequencing analyses and real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) showed that PtrA plays a dual regulatory role in the virulence systems of PA: negatively regulates the type-III secretion system (T3SS) and positively regulates the quorum-sensing system (QS). The ptrA mutant attenuated extracellular virulence related to QS like pyocyanin, elastase, rhamnolipids, proteolytic activity, and biofilm production. According to adhesion and invasion experiments, PtrA can not only contribute to the adhesiveness but also the invasive of PA. Moreover, the PtrA-mediated regulation of PA pathogenicity was determined both in vivo and in vitro through cytotoxicity and Galleria mellonella survival experiments. In addition, apart from virulence, PtrA was found to influence the carbapenems resistance of PA. After deleting ptrA, the minimum inhibitory concentration (MIC) of carbapenems antibiotics was decreased by 2-fold, while a 2–8 fold increase was noted for the complemented strain.ConclusionOur findings establish that PtrA exerts a regulatory role in both pathogenicity and carbapenems resistance of PA. This work may shed light on a novel target for the clinical treatment of PA.

Study of adhesive self-degrading gel for wellbore sealing

In this study, a self-degrading gel with high adhesion was synthesized by acrylamide, acrylic acid and an unstable cross-linker. It was used for the pressurized operation of oil and gas wells. The degradation time, adhesion and plugging performance of the gel were investigated by degradation experiments, adhesion experiments and plugging experiments. To a certain extent, it was found that the concentration of the reactants had different effects on the degradation time and adhesion friction of the gels. In addition, the adhesion friction varies due to compressional deformation of the gel by compression. The blocking ability of the gels was mainly related to the adhesion friction. The blocking capacity of high-strength horizontal gels is linearly related to the adhesion friction. The sealing capacity of low strength horizontal gel is non-linearly related to the adhesion friction. Compared with conventional gel blocking operation, the gel breaking operation at the end of gel blocking operation does not require additional injection of gel breaking agent due to the introduction of unstable crosslinker. The gel degradation time can be controlled by designing the formulation to achieve rapid gel breakage and rejection. It saves time cost and economic cost. The highly viscous self-degrading gel can be used as a wellbore pressure packer for oil and gas wells under pressure.

Evaluation of an Efficient and Skin-Adherent Semisolid Sunscreen Nanoformulation

Introduction: Sunscreens are substances applied on the skin surface to protect the skin from the harmful effects of UV light. Nanoparticles can increase the retention time of the sunscreen on the skin surface and its efficacy, by acting as physical barriers. The present investigation aimed to evaluate the influence of the chitosan coating of benzophenone-3-loaded lipid-core nanocapsules (CH-LCN) on the skin adhesion and photoprotective effect of the sunscreen. Methods: CH-LNC were obtained by the interfacial deposition of preformed polymer. A suitable semisolid formulation was obtained by using hydroxyethyl cellulose as the gel-forming polymer. Skin adhesion experiments were performed in vitro by applying the formulation on porcine skin and keeping it under water at 32 °C for up to 60 min. Photoprotective effect was analyzed in vitro by the capacity of the formulations to protect a photo unstable substance (resveratrol) from degradation under UV light. Results: CH-LNC presented size of around 150 nm, with low polydispersity, positive zeta potential, due to chitosan, and benzophenone-3 encapsulation efficiency of close to 100% (3 mg/mL). The proposed gel presented suitable consistence and pH for skin application and benzophenone-3 concentration of around 3 mg/g. Although coated and uncoated lipid-core nanocapsules increased benzophenone-3 skin adhesion after 10 min of water immersion, only the nanoparticles coated with chitosan were able to do so after 60 min. The chitosan coating of the nanocapsules increased the photoprotection of the sunscreen under UVA and UVB light after 60 min of exposure, probably due to the film-forming properties of chitosan. Conclusion: The chitosan coating of CH-LCN increased the skin adhesion and the photoprotective effect of the sunscreen.

The effect of thiol functional groups on bovine serum albumin/chitosan buccal mucoadhesive patches

In this research, the effect of thiol functional groups on bovine serum albumin (BSA)/chitosan (Chi) based buccal mucoadhesive patch was investigated. Thiolated BSA (BSA-SH) was prepared via 2-mercaptoethanol. FTIR and 1H NMR results confirmed that BSA-SH was synthesized successfully. The buccal mucoadhesive patches were fabricated by the solvent casting method. Following the structural characterization of BSA/Chi and BSA-SH/Chi buccal patches, the mechanical characterization was performed by tensile tests. The drug release from triamcinolone acetonide (TR) loaded buccal patches was evaluated in-vitro in simulated salivary. According to the ex-vivo buccal adhesion experiments, the mechanical and mucoadhesion properties of BSA-SH/Chi buccal patch had improved compared to BSA/Chi buccal patch. The total cumulative TR permeated after 12 h was higher for BSA-SH/Chi than BSA/Chi buccal patches. The developed mucoadhesive buccal patches were found to be biocompatible in vitro. To conclude, the thiolated BSA-SH/Chi buccal adhesive patch is a promising biomaterial for a satisfied drug delivery, which provides advantages for various oral applications.

Poria Acid, Triterpenoids Extracted from Poria cocos, Inhibits the Invasion and Metastasis of Gastric Cancer Cells.

Background: Poria cocos (P. cocos) is an important medicinal fungus in traditional Chinese medicine. Poria acid (PA), a triterpenoid compound, is an effective component of traditional Chinese medicine P. cocos. This experiment investigated the anti-gastric cancer biological activity of PA in vitro. Methods: The effect of PA on the viability of gastric cancer cells was detected by the thiazolyl blue (MTT) assay. Cell adhesion assays were used to detect changes in the adhesion of cells treated after PA (0, 20, 40, and 80 µmol/L). The ability of cell invasion and migration were detected by Transwell assays and wound healing assays. A high-content imaging system was used to dynamically record the motility of the gastric cancer cells after PA (0, 20, 40, and 80 µmol/L) treatment. Western blotting was used to detect the expression of epithelial–mesenchymal transformation (EMT), invasion and migration related proteins. Results: The MTT assay showed that the proliferation of gastric cancer cells was significantly inhibited after PA treatment. Cell adhesion experiments showed that the adhesion of gastric cancer cells was significantly decreased after PA treatment. Compared with the control group, the wound healing area of the gastric cancer cells treated with different concentrations of PA decreased. The Transwell assay showed that the number of gastric cancer cells passing through the cell membrane were significantly reduced after PA treatment. In addition, after PA treatment, the cells’ movement distance and average movement speed were significantly lower than those of the control group. Finally, PA can significantly alter the expression of EMT-related proteins E-cadherin, N-cadherin, and Vimentin and decreased the expressions of metastasis-related proteins matrix metalloproteinase (MMP) 2, MMP-9 and tissue inhibition of matrix metalloproteinase (TIMP)1 in the gastric cancer cells. Conclusions: Triterpenoids from P. cocos have significant biological activity against gastric cancer, and the mechanism may be involved in the process of epithelial–mesenchymal transformation.

Biochar by Spirulina platensis promotes the antifouling effect of Cu2O in styrene-acrylic resin coating

Biofouling by microalgae and other organism is a harmful phenomenon shared among all floating and subwater facilities. Using the antifouling coatings is the major measure to reduce the adhesion. This paper reports a kind of composite coating made of cuprous oxide (Cu2O), biochar and styrene-acrylic (SA) resin. Microalgae Spirulina platensis was used to prepare the biochar by pyrolysis, and then different amount of Cu2O particles were loaded on the biochar by chemical liquid deposition. Greater specific surface area to 181.3 m2·g−1of the Spirulina platensis biochar was obtained after pyrolysis at 600 °C. Cubic Cu2O particles with the size of about 100–200 nm were uniformly deposited in the folds and pores of the biochar. The SA composite coating has a faster release of Cu2+ to maintain about 60 μg·L−1 with a longer term compared those SA coatings without biochar. Adhesion experiments with microalgae Chlorella vulgaris and Nannochloropsis oceanica showed that the antifouling efficiencies increased 49.1%, 30.3% for the Cu2O loaded SA coatings (0.05 wt%), and 93.0%, 92.8% for the Cu2O-biochar-SA composite coatings respectively. The synergistic effect of the biocide of copper ions and the photocatalysis of Cu2O improved by compositing with biochar contribute to the promotion of the antifouling performance.

A Membrane with Strong Resistance to Organic and Biological Fouling Using Graphene Oxide and D-Tyrosine as Modifiers.

Membrane fouling markedly influences the service life and performance of the membrane during the using process. Herein, hydrophilic polyvinylidene fluoride (PVDF) nanocomposite (P-GO-DAA) membranes with antifouling and anti-biofouling characteristics were fabricated by employing graphene oxide (GO) and different concentrations of D-Tyrosine. The structural properties of the prepared nanocomposite membranes as well as pure PVDF membranes were characterized using FTIR, XPS, SEM, AFM, and contact angle analysis. It was found that the introduction of GO fillers made an excellent antifouling performance compared to pure PVDF indicated by the pure water flux, flux recovery rate, and rejection rate during ultrafiltration experiments as a result of the formation of the hydrophilic and more porous membrane. In particular, the nanocomposite membranes showed an increased flux of 305.27 L/(m2·h) and the rejection of 93.40% for the mixed pollutants solution (including Bull Serum Albumin, Sodium Alginate, and Humic Acid). Besides, the outstanding anti-biofouling activity was shown by the P-GO-DAA membrane with the properties of D-Tyrosine for inhibiting biofilm formation during the bacterial adhesion experiments. Furthermore, the adhesion ratio of bacteria on the membrane was 26.64% of the P-GO-DAA membrane compared to 84.22% of pure PVDF. These results were confirmed by CLSM.

Effect of Surface Tooling Techniques of Medical Titanium Implants on Bacterial Biofilm Formation In Vitro.

The aim of this study was to assess the biofilm formation of Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli on titanium implants with CAD-CAM tooling techniques. Twenty specimens of titanium were studied: Titanium grade 2 tooled with a Planmeca CAD-CAM milling device (TiGrade 2), Ti6Al4V grade 5 as it comes from CAD-DMLS device (computer aided design-direct metal laser sintering device) (TiGrade 5), Ti6Al4V grade 23 as it comes from a CAD-CAM milling device (TiGrade 23), and CAD-DMLS TiGrade 5 polished with an abrasive disc (TiGrade 5 polished). Bacterial adhesion on the implants was completed with and without saliva treatment to mimic both extraoral and intraoral surgical methods of implant placement. Five specimens/implant types were used in the bacterial adhesion experiments. Autoclaved implant specimens were placed in petri plates and immersed in saliva solution for 30 min at room temperature and then washed 3× with 1× PBS. Bacterial suspensions of each strain were made and added to the specimens after saliva treatment. Biofilm was allowed to form for 24 h at 37 °C and the adhered bacteria was calculated. Tooling techniques had an insignificant effect on the bacterial adhesion by all the bacterial strains studied. However, there was a significant difference in biofilm formation between the saliva-treated and non-saliva-treated implants. Saliva contamination enhanced S. mutans, S. aureus, and E. faecalis adhesion in all material types studied. S. aureus was found to be the most adherent strain in the saliva-treated group, whereas E. coli was the most adherent strain in the non-saliva-treated group. In conclusion, CAD-CAM tooling techniques have little effect on bacterial adhesion. Saliva coating enhances the biofilm formation; therefore, saliva contamination of the implant must be minimized during implant placement. Further extensive studies are needed to evaluate the effects of surface treatments of the titanium implant on soft tissue response and to prevent the factors causing implant infection and failure.

A simple, safe and easily accessible polyvinyl alcohol hydrogel for wound cleaning.

Acute wounds are often contaminated by some kind of filth, and fluids are usually used to wash away the dirt, but the force of the fluid may cause secondary injury at the wound site or even increase the risk of infection. Hydrogels have several advantages over liquid scouring since they are less intense, more portable, and easier to control. In this study, poly(vinyl alcohol) was used to prepared a series of hydrogels, which were tested in terms of their properties and abilities to clean simulated dirty wounds. Simulated dirt and bacterial (Serratia marcescens) adhesion experiments demonstrated that they could effectively adhere to a certain amount of dirt or bacteria to achieve the purpose of wound cleaning. In addition to the bacterial adhesion, the antibacterial experiments also proved that the hydrogels have a certain inhibitory effect on the proliferation of E.coli and S.aureus. The hydrogels could change shape freely and exhibited excellent biocompatibility, ductility, and self-healing capabilities, which increase their service life and make them more suitable for treating wounds or acting as protection buffers. Based on all these characteristics, the developed hydrogel may be a potentially valuable material for wound cleaning.

Shape fidelity, mechanical and biological performance of 3D printed polycaprolactone-bioactive glass composite scaffolds

Direct ink writing (DIW) is a promising extrusion-based 3D printing technology, which employs an ink-deposition nozzle to fabricate 3D scaffold structures with customizable ink formulations for tissue engineering applications. However, determining the optimal DIW process parameters such as temperature, pressure, and speed for the specific ink is essential to achieve high reproducibility of the designed geometry and subsequent mechano-biological performance for different applications, particularly for porous scaffolds of finite sizes (total volume > 1000 mm3) and controlled pore size and porosity. The goal of this study was to evaluate the feasibility of fabricating Polycaprolactone (PCL) and bio-active glass (BG) composite-based 3D scaffolds of finite size using DIW. 3D-scaffolds were fabricated either as cylinders (10 mm diameter; 15 mm height) or cubes (5 × 5 × 5 mm3) with height/width aspect ratios of 1.5 and 1, respectively. A rheological characterization of the PCL-BG inks was performed before printing to determine the optimal printing parameters such as pressure and speed for printing at 110 °C. Microstructural properties of the scaffolds were analyzed in terms of overall scaffold porosity, and in situ pore size assessments in each layer (36 pores/layer; 1764 pores per specimen) during their fabrication. Measured porosity of the fabricated specimens—PCL: x¯ =46.94%, SD = 1.61; PCL-10 wt%BG: x¯ = 48.29%, SD = 5.95; and PCL-20 wt% BG: x¯=50.87%, SD = 2.45—matched well with the designed porosity of 50%. Mean pore sizes—PCL [x¯ = 0.37 mm (SD = 0.03)], PCL-10%BG [x¯ = 0.38 mm (SD = 0.07)] and PCL-20% BG [x¯ = 0.37 mm (SD = 0.04)]—were slightly fairly close to the designed pore size of 0.4 mm. Nevertheless there was a small but consistent, statistically significant (p < 0.0001) decrease in pore size from the first printed layer (PCL: 0.39 mm; PCL-10%BG: 0.4 mm; PCL-20%BG: 0.41 mm) to the last. SEM and micro-CT imaging revealed consistent BG particle distribution across the layers and throughout the specimens. Cell adhesion experiments revealed similar cell adhesion of PCL-20 wt% BG to pure PCL, but significantly better cell proliferation – as inferred from metabolic activity – after 7 days, although a decrease after 14 days was noted. Quasi-static compression tests showed a decrease in compressive yield strength and apparent elastic modulus with increasing BG fraction, which could be attributed to a lack of adequate mechanical bonding between the BG particles and the PCL matrix. The results show that the inks were successfully generated, and the scaffolds were fabricated with high resolution and fidelity despite their relatively large size (>1000 mm3). However, further work is required to understand the mechano-biological interaction between the BG particle additives and the PCL matrix to improve the mechanical and biological properties of the printed structures.

Effects of Mg-Nd-Gd-Sr alloy on bone marrow mesenchymal stem cell function derived from SD rats

Introduction The aim of this study was to determine the effect of a new type of Mg-3Nd-1Gd-0.3Sr-0.2Zn-0.4Zr (abbreviated to Mg-Nd-Gd-Sr) alloy on bone marrow mesenchymal stem cell (BMSCs) function derived from SD rats. Methods BMSCs were first isolated and cultured in vitro using the whole bone marrow adherence method, and identified by BMSC surface biomarkers and osteogenic induction. The in vitro biological safety of the Mg-Nd-Gd-Sr alloy was studied by cytotoxicity and apoptosis experiments, and the in vitro biological functions were studied by cell adhesion and cell proliferation experiments. Results The results showed that high-purity BMSCs were isolated using the whole bone marrow adherence method. Flow cytometry showed high expression of CD44 and CD90, and low expression of CD31 and CD45 in the BMSCs. Osteogenic induction showed that the BMSCs differentiated into osteoblasts, and mineralized nodules were observed. The cytotoxicity of the Mg-Nd-Gd-Sr alloy to SD rat BMSCs was 0–1 grade, suggesting that the Mg-Nd-Gd-Sr alloy had no significant cytotoxic effect on SD rat BMSCs; compared with the control group, there was no significant cell apoptosis in any of the experimental groups ( p &gt; 0.05). Cell adhesion experiments showed that the number of adherent cells increased with the duration of culture with the exception of the 100% concentration group; compared with the control group, the 75% concentration group had the highest number of adherent cells at the 1st, 3rd, 5th, and 7th hours ( p &lt; 0.05). Cell proliferation experiments showed that the number of cells in all experiment groups was higher than the control group ( p &lt; 0.05) on the 1st, 3rd, 5th, and 7th days, with the highest number of cells in the 75% concentration group ( p &lt; 0.05). Conclusion Our data indicate that the extracts of new type of Mg-Nd-Gd-Sr alloy has no apparent cytotoxicity to BMSCs, does not affect cell apoptosis, and has good biocompatibility. Different concentrations of Mg-Nd-Gd-Sr alloy extracts promoted the adhesion and proliferation of BMSCs. The alloy had good biological functions, and is thus a promising bone repair material.

Establishing the selective phospholipid membrane coordination, permeation and lysis properties for a series of 'druggable' supramolecular self-associating antimicrobial amphiphiles.

The rise of antimicrobial resistance remains one of the greatest global health threats facing humanity. Furthermore, the development of novel antibiotics has all but ground to a halt due to a collision of intersectional pressures. Herein we determine the antimicrobial efficacy for 14 structurally related supramolecular self-associating amphiphiles against clinically relevant Gram-positive methicillin resistant Staphylococcus aureus and Gram-negative Escherichia coli. We establish the ability of these agents to selectively target phospholipid membranes of differing compositions, through a combination of computational host:guest complex formation simulations, synthetic vesicle lysis, adhesion and membrane fluidity experiments, alongside our novel 1H NMR CPMG nanodisc coordination assays, to verify a potential mode of action for this class of compounds and enable the production of evermore effective next-generation antimicrobial agents. Finally, we select a 7-compound subset, showing two lead compounds to exhibit ‘druggable’ profiles through completion of a variety of in vivo and in vitro DMPK studies.

Adhesion of viscoelastic media: an assessment of a recent JKR-like solution

Adhesion of soft compliant solids is irreversible and rate-dependent. As a result, two different paths are observed in loading-unloading adhesion experiments because of dissipation occurring in the unloading phase. An effective surface energy is usually introduced to take account of such dissipation.Here, by exploiting a recent theoretical solution developed to study the detachment of a rigid sphere from a viscoelastic substrate (Violano et al., 2021), two different approaches are considered to calculate the surface energy. The first approach is based on the phenomenological equation derived by Gent & Schultz (A. N. Gent & J. Schultz, 1972), the latter exploits Persson & Brener theory for viscoelastic crack propagation (B. N. J. Persson & E. A. Brener, 2005).In both cases, results are observed to be in good agreement with experimental data taken from the literature.

Divisions in a Fibrillar Adhesive Increase the Adhesive Strength.

To realize the potential of bioinspired fibrillar adhesive applications ranging from biomedical devices to robotic grippers, there has been a significant effort to improve their adhesive strength and understanding of the underlying adhesion and detachment mechanisms. These efforts include changes to the backing layer, which connects the roots of all of the pillars in the fibrillar adhesive. However, previous approaches such as thickness or elastic modulus changes are selectively advantageous to the adhesive strength depending on the substrate condition because of the trade-off between conformity to misaligned/rough surfaces and increased interfacial stress concentrations. In this work, we explore mechanical divisions (cuts) in the backing layer as a new approach to improve the adhesive strength without this trade-off. We combine experiments and finite element analysis (FEA) to study the effect of the divisions, which decouples the mechanical interaction between the pillars on the divided layers, and show that the adhesive strength can be improved regardless of the substrate condition. Tensile adhesion experiments show increased adhesive strength with cuts to a micropost array (150 μm diameter posts) by approximately 25% for 4 divisions. In situ imaging of pillar detachment shows a transition of the detachment process from a peel-like detachment to a random detachment sequence. FEA simulations of the detachment process suggest that the increased strength may originate from a simultaneous enhancement of the load distribution between the pillars and the compliance of the backing layer.

Effect of Rhamnolipids and Lipopolysaccharides on the Bioleaching of Arsenic-Bearing Waste

The adsorption of biosurfactants and polysaccharides changes the surface properties of solid particles, which is important for controlling the release of arsenic compounds from the solid phase and preventing undesirable bioleaching. Microbial leaching and scorodite adhesion experiments, including pure and modified mineral material, were conducted in a glass column with a mineral bed (0.8–1.2 mm particle size) to test how rhamnolipids (Rh) and lipopolysaccharides (LPS) affect surface properties of mineral waste from Złoty Stok (Poland) and secondary bio-extraction products (scorodite). Adsorption tests were conducted for both solid materials. The adsorption of Rh and LPS on the solids was shown to modify its surface charge, affecting bioleaching. The highest bio-extraction efficiency was achieved for arsenic waste with adsorbed rhamnolipids, while the lowest, for the LPS-modified mineral. Under acidic circumstances (pH~2.5), the strongly negative zeta potential of arsenic-bearing waste in the presence of Rh creates conditions for bacteria adhesion, leading to the intensification of metal extraction. The presence of a biopolymer on the As waste surface decreases leaching efficiency and favours the scorodite’s adhesion.

Preparation of superhydrophobic glass surface with high adhesion

This paper prepared the superhydrophobic surfaces on the glass substrate by the ablation of grid microstructures using picosecond laser and subsequence chemical modifications by silanization. The novelties in this research are the superhydrophobic surfaces prepared with high adhesion and further exploration of the effect of abrasion on its superhydrophobic and adhesion properties. The surface morphologies were characterized by a scanning electron microscope (SEM) to reveal the effect of laser parameters on micro-nano structure. The water contact angles and surface roughness values were measured to illustrate the effect laser parameters on surface wettability. The surface energy was calculated to prove the correlation between lower surface energy and superhydrophobicity. The chemical composition of the surfaces was detected by an X-ray photoelectron spectroscopy (XPS) to explore the mechanism of changes in wettability from the reaction of fluorosilane and glass materials perspectives. The surface adhesion experiments were also performed to reveal the relationship between surface adhesion and laser parameters. The results indicated that the micro/nano structure by laser-induced were substantially dependent on the laser energy and significantly affected the adhesion. However, the number of scans slightly affected the surface morphologies and the adhesion. Finally, the abrasion resistance experiments were conducted to observe the relationship between abrasion cycle to contact angle and adhesion.

Hypoxic Storage of Red Blood Cells: Assessment of Adhesion Properties Using a Standardized Endothelium-on-a-Chip Microfluidic Platform

Background: Blood transfusions are routine medical procedures in which stored blood or blood products (i.e., red blood cells, RBCs) are given to the patient to prevent adverse health outcomes due to acute or chronic anemia. The current regulations require RBCs to be stored at 4 ºC not more than 42 days before a transfusion. However, RBCs undergo extensive rheological changes during storage and may contribute to complications associated with transfusion. Hemanext has recently introduced an innovative storage system to ameliorate such storage lesions, in which RBCs are stored in a hypoxic environment, and thus they are exposed to much lower oxidative stress during storage. In this study, we report the changes in adhesion properties of stored RBCs to human endothelial cells following a 42-day storage in normoxia vs hypoxia, using a standardized endothelialized microfluidic platform: Endothelium-on-a-chip.Methods: Two units of 1-day old blood type O positive leukocyte reduced RBCs in additive solution were pooled and divided into equal aliquots (300mL each) A and B. Unit A was stored under conventional normoxic storage condition at 4°C for 42 days. Unit B was deoxygenated so that the percent oxygen saturation of the hemoglobin was less than 20%. The deoxygenated RBCs were stored in an oxygen impermeable storage bag for 42 days at 4°C. Adhesion levels were tested at the beginning (baseline, Week 1) and the end of the storage period (Week 6). To conduct the adhesion experiments, human umbilical vein endothelial cells (HUVECs) were first cultured within microfluidic channels under flow for at least 48 hours. Next, the HUVECs were treated with 40 µM heme for 4 hours at 37 ºC [1]. RBCs were centrifuged to remove the storage buffer and resuspended in basal cell culture medium (EGM, Lonza, Morristown, USA) supplemented with 10 mM HEPES at a hematocrit of 40%. A 15 µl of RBC solution was then injected over heme-activated HUVECs at a shear stress of 1 dyne/cm 2 followed by a 10-minute rinse with fresh basal culture medium to remove non-adherent RBCs. At the end of the experiment, adherent erythrocytes were manually quantified. Control experiments were conducted with non-activated HUVECs.Results: We found that RBCs that were stored under conventional normoxic condition displayed higher adhesion to heme-activated HUVECs than hypoxic condition as illustrated in Figure 1A and 1B. The baseline adhesion levels (Week 1) to non-activated HUVECs (control) were negligible (Fig. 1C, normoxia: 13±6; hypoxia: 18±10, p>0.05) while both cell populations had considerable adhesion levels to heme-activated HUVECs at baseline (Fig. 1C, normoxia: 372±59; hypoxia: 335±37). Following a 6-week storage, adhesion of RBCs stored in normoxia to heme-activated HUVECs was higher compared to those stored in hypoxic conditions while the p-value was not significant, which was likely due to the limited sample size (Fig. 1C, 1782±519 vs 594±55, p=0.08, N=3). These results suggest that storage-mediated RBC adhesion to heme-activated HUVECs may be ameliorated by the novel hypoxic-storage condition.Discussion: This study showed a decrease in the adhesion of hypoxic RBCs to heme-activated HUVECs when compared to conventionally stored RBCs for transfusion. This result suggests that hypoxic RBCs may reduce the risk of developing vaso-occlusion (VOC) after RBC transfusion in patients such as in sickle cell disease where adhesion to heme-activated HUVECs has been implicated in the pathogenesis of VOC [1].Acknowledgements: This work was funded by Hemanext. The authors would like to thank the Ohio Third Frontier Technology Validation and Start-up Fund (TVSF) and National Science Foundation Phase-I Small Business Technology Transfer (STTR) award, which supported this work in part. Stored RBCs were donated by Hemanext.Reference:1. Kucukal, E., et al., American Journal of Hematology, 2018. 93(8): p.1050-1060 [Display omitted] DisclosuresKucukal: BioChip Labs: Current Employment, Patents & Royalties. Kocevar: BioChip Labs: Current Employment. Nayak: BioChip Labs: Current Employment. Sowemimo-Coker: Hemanext: Current Employment. Zak: BioChip Labs: Current Employment, Current holder of stock options in a privately-held company; XaTek: Current Employment, Current holder of stock options in a privately-held company; TecTraum Inc: Current Employment, Current holder of stock options in a privately-held company. Omert: Hemanext: Current Employment. Gurkan: Biochip Labs: Patents & Royalties; Hemex Health, Inc.: Current Employment, Patents & Royalties; Dx Now Inc.: Patents & Royalties; Xatek Inc.: Patents & Royalties.

In vitro adhesion of Bacillus sp. and Enterobacter sp. probiotics on intestinal epithelial cells of red tilapia (Oreochromis sp.) and the application effects on the fish growth and survival rate

This research aimed to determine the adhesion of Bacillus sp. (PCP1) and Enterobacter sp. (JC10) on intestinal epithelial cells of red tilapia (Oreochromis sp.) and the effect of the probiotics application in feed on fish growth, survival rate, and feed conversion ratio. In vitro adhesion test was performed by using 108 cells/ml of bacteria, and 105 cells/ml of epithelial cells for 1 hour of incubation. The probiotics were added to the fish pellet with the dose of 5 x 104 CFU/g of feed with four treatments, including probiotic application every three days, seven days, without probiotic, and commercial probiotic application every three days. Each treatment consists of three replications. Red tilapia is maintained for 30 days in fiberglass ponds. The feed is given two times per day with a dose of 5 % of the biomass. The adhesion experiment results showed that Bacillus sp. (PCP1) and Enterobacter sp. (JC10) have adherence abilities higher than the commercial probiotics. The application of probiotics in tilapia for one month did not affect the fish growth, survival rate, and feed conversion ratio (P > 0.05). Probiotic application in a longer period is needed to be addressed.

Antibacterial fluorescent nano-sized lanthanum-doped carbon quantum dot embedded polyvinyl alcohol for accelerated wound healing

Bacteria is one of the main culprits that cause human diseases and pose long-term challenges to people’s health. Rare earth elements have unique antibacterial advantages, but little research is available. In this paper, we reported an antibacterial composite film based on lanthanum-doped carbon quantum dot nanoparticles (La@N-P-CQDs) and polyvinyl alcohol (PVA) film for fluorescence of antibiotics and accelerating wound healing. PVA/La@N-P-CQDs composite film presented excellent hydrophilicity, biocompatibility, fluorescence intensity, and antibacterial effects. The antibacterial activity of La@N-P-CQDs was evaluated by employing antibacterial assay using Escherichia coli (E.coli)and Staphylococcus aureus (S.aureus) in vitro. La@N-P-CQDs showed enhanced antibacterial activity compared with N-P-CQDs. Moreover, the PVA/La@N-P-CQDs composite film with 0.5 mg/mL La@N-P-CQDs showed better antibacterial capability and wound healing performance than PVA and PVA/N-P-CQDs films in bacterial adhesion experiment. PVA/La@N-P-CQDs composite film could be used for wound dressing in vivo experiment and had no side effects on major organs in mice. The antibacterial composite film significantly promoted in vivo wound healing process because of its multifunctional properties. Therefore, it was an excellent candidate for wound dressing.