scholarly journals Inner surface of Nepenthes slippery zone: ratchet effect of lunate cells causes anisotropic superhydrophobicity

2020 ◽  
Vol 7 (3) ◽  
pp. 200066
Author(s):  
Lixin Wang ◽  
Shuoyan Zhang ◽  
Shanshan Li ◽  
Shixing Yan ◽  
Shiyun Dong
Keyword(s):  
Water Droplet ◽  
Angle Measurement ◽  
Dense Layer ◽  
Ultrapure Water ◽  
Ratchet Effect ◽  
Sliding Angle ◽  
Static Contact ◽  
Inner Surface ◽  
Structure Observation ◽  
Different Order

Inner surface of Nepenthes slippery zone shows anisotropic superhydrophobic wettability. Here, we investigate what factors cause the anisotropy via sliding angle measurement, morphology/structure observation and model analysis. Static contact angle of ultrapure-water droplet exhibits the value of 154.80°–156.83°, and sliding angle towards pitcher bottom and up is 2.82 ± 0.45° and 5.22 ± 0.28°, respectively. The slippery zone under investigation is covered by plenty of lunate cells with both ends bending downward, and a dense layer of wax coverings without directional difference in morphology/structure. Results indicate that the slippery zone has a considerable anisotropy in superhydrophobic wettability that is most likely caused by the lunate cells. A model was proposed to quantitatively analyse how the structure characteristics of lunate cells affect the anisotropic superhydrophobicity, and found that the slope/precipice structure of lunate cells forms a ratchet effect to cause ultrapure-water droplet to roll towards pitcher bottom/up in different order of difficulty. Our investigation firstly reveals the mechanism of anisotropic superhydrophobic wettability of Nepenthes slippery zone, and inspires the bionic design of superhydrophobic surfaces with anisotropic properties.

Development of polyurethane-based superhydrophobic coatings on steel surfaces

2020 ◽  
Vol 378 (2167) ◽  
pp. 20190446 ◽  
Author(s):  
Mukesh Kumar Meena ◽  
Balraj Krishnan Tudu ◽  
Aditya Kumar ◽  
Bharat Bhushan
Keyword(s):  
Contact Angle ◽  
Steel Surface ◽  
Mechanical Stability ◽  
Industrial Applications ◽  
Angle Measurement ◽  
Coated Steel ◽  
Corrosion Properties ◽  
Static Contact ◽  
Steel Surfaces ◽  
Self Cleaning

In this study, a superhydrophobic coating on steel surface has been developed with polyurethane, SiO 2 nanoparticles and hexadecyltrimethoxysilane by using a spin-coating technique. Characterization of the coated steel surface was done by using the contact angle measurement technique, scanning electron microscopy and Fourier transform infrared spectroscopy. With a water tilt angle of 4° ± 2° and static contact angle of 165° ± 5°, the coated surface shows a superhydrophobic and self-cleaning nature. Chemical, thermal, mechanical stability tests and droplet dynamic studies were done to evaluate performance of the coating. Excellent self-cleaning, anti-fogging and anti-corrosion properties of coated steel surfaces make them ideal for industrial applications. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 3)’.

Impact of DMPEI on biofilm adhesion on latex urinary catheter

2021 ◽  
Vol 15 ◽  
Author(s):  
Vinícius S. Tarabal ◽  
Flávia Gontijo Silva ◽  
Ruben D. Sinisterra ◽  
Daniel Gonçalves ◽  
Jose Silva ◽  
...  
Keyword(s):  
Contact Angle ◽  
Medical Devices ◽  
Outer Surface ◽  
Biofilm Formation ◽  
New Technologies ◽  
Angle Measurement ◽  
E Coli ◽  
Starting Point ◽  
Inner Surface ◽  
Catheter Surface

Background: Microorganisms can migrate from the external environment to the patient's organism through the insertion of catheters. Despite being indispensable medical devices, the catheter surface can be colonized by mi-croorganisms and become a starting point for biofilm formation. Therefore, new technologies are being developed in order to modify surfaces to prevent the adhesion and survival of microorganisms.Patents with the use of DMPEI have been filed. Objective: Objective: In the present work, we coated latex catheter surfaces with 2 mg mL-1 DMPEI in different solvents, evaluated the wettability of the surface and the anti-biofilm activity of the coated catheter against Escherichia coli, Staphylococcus aureus, and Candida albicans. Methods: We coated the inner and outer catheter surface with 2 mg mL-1 of DMPEI solubilized in butanol, dime-thylformamide, and cyclohexanone and were analyzed visually. Contact angle measurement allowed the analysis of the wettability of the surfaces. The CFU mL-1 counting evaluated E. coli, S. aureus, and C. albicans adhesion onto the control and treated surfaces. Results: The contact angle decreased from 50.48º to 46.93º on the inner surface and 55.83º to 50.91º on the outer surface of latex catheters coated with DMPEI. The catheter coated with DMPEI showed anti-biofilm activity of 83%, 88%, and 93% on the inner surface and 100%, 92%, and 86% on the outer surface for E. coli, S. aureus, and C. albicans, respectively. Conclusion: Latex catheter coated with DMPEI efficiently impaired the biofilm formation both in the outer and inner surfaces showing a potential antimicrobial with high anti-biofilm activity for medical devices.

scholarly journals Development of Energy-Efficient Superhydrophobic Polypropylene Fabric by Oxygen Plasma Etching and Thermal Aging

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2756
Author(s):  
Shinyoung Kim ◽  
Ji-Hyun Oh ◽  
Chung Hee Park
Keyword(s):  
Energy Consumption ◽  
Plasma Etching ◽  
Thermal Aging ◽  
Energy Efficient ◽  
Oxygen Plasma ◽  
Transmission Rate ◽  
Sliding Angle ◽  
Static Contact ◽  
Polypropylene Fabric ◽  
Oxygen Plasma Etching

This study developed a human-friendly energy-efficient superhydrophobic polypropylene (PP) fabric by oxygen plasma etching and short-term thermal aging without additional chemicals. The effect of the microroughness on the superhydrophobicity was examined by adjusting the weave density. After the PP fabric was treated with oxygen plasma etching for 15 min and thermal aging at 120 °C for 1 h (E15H120 1 h), the static contact and shedding angles were 162.7° ± 2.4° and 5.2° ± 0.7° and the energy consumption was 136.4 ± 7.0 Wh. Oxygen plasma etching for 15 min and thermal aging at 120 °C for 24 h (E15H120 24 h) resulted in a static contact and shedding angle of 180.0° ± 0.0° and 1.8° ± 0.2° and energy consumption of 3628.5 ± 82.6 Wh. E15H120 1 h showed a lower shedding angle but had a higher sliding angle of 90°. E15H120 24 h exhibited shedding and sliding angles of less than 10°. Regardless of the thermal aging time, superhydrophobicity was higher in high-density fabrics than in low-density fabrics. The superhydrophobic PP fabric had a similar water vapor transmission rate and air permeability with the untreated PP fabric, and it showed a self-heading property after washing followed by tumble drying and hot pressing.

Laser Texturing of Plasma Electrolytically Oxidized Aluminum 6061 Surfaces for Improved Hydrophobicity

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
B. S. Yilbas ◽  
A. Matthews ◽  
C. Karatas ◽  
A. Leyland ◽  
M. Khaled ◽  
...  
Keyword(s):  
Laser Treatment ◽  
Water Droplet ◽  
Treatment Process ◽  
Surface Characteristics ◽  
High Water ◽  
Contact Angles ◽  
Laser Surface Texturing ◽  
Dense Layer ◽  
Textured Surface ◽  
X Ray

Laser surface texturing of plasma electrolytically oxidized aluminum 6061 alloy has been carried out through a controlled surface ablation under a high pressure nitrogen gas assistance. Morphological and metallurgical changes in the laser-treated region were examined using optical, scanning electron, and atomic force microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction phase analysis. The hydrophobicity of the textured surface was assessed through water droplet contact angle measurements. It was found that a dense layer with a nanotexture/microtexture is developed at the surface after the laser treatment process. The assessment of the surface characteristics reveals that a superhydrophobic surface results from the laser treatment process; in which case, high water droplet contact angles are measured over the treated surface, which can be explained by known models of texture-induced superhydrophobicity.

scholarly journals A Novel Strategy to Coat Dopamine-Functionalized Titanium Surfaces With Agarose-Based Hydrogels for the Controlled Release of Gentamicin

2021 ◽  
Vol 11 ◽  
Author(s):  
H. Melis Soylu ◽  
Pascale Chevallier ◽  
Francesco Copes ◽  
Federica Ponti ◽  
Gabriele Candiani ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Controlled Release ◽  
Contact Angle Measurement ◽  
Elisa Test ◽  
Angle Measurement ◽  
Release Time ◽  
Spinal Implants ◽  
Static Contact ◽  
Low Cytotoxicity ◽  
Novel Strategy

IntroductionThe use of spinal implants for the treatment of back disorders is largely affected by the insurgence of infections at the implantation site. Antibacterial coatings have been proposed as a viable solution to limit such infections. However, despite being effective at short-term, conventional coatings lack the ability to prevent infections at medium and long-term. Hydrogel-based drug delivery systems may represent a solution controlling the release of the loaded antibacterial agents while improving cell integration. Agarose, in particular, is a biocompatible natural polysaccharide known to improve cell growth and already used in drug delivery system formulations. In this study, an agarose hydrogel-based coating has been developed for the controlled release of gentamicin (GS).MethodsSand blasted Ti6Al4V discs were grafted with dopamine (DOPA) solution. After, GS loaded agarose hydrogels have been produced and additioned with tannic acid (TA) and calcium chloride (CaCl2) as crosslinkers. The different GS-loaded hydrogel formulations were deposited on Ti6Al4V-DOPA surfaces, and allowed to react under UV irradiation. Surface topography, wettability and composition have been analyzed with profilometry, static contact angle measurement, XPS and FTIR spectroscopy analyses. GS release was performed under pseudo-physiological conditions up to 28 days and the released GS was quantified using a specific ELISA test. The cytotoxicity of the produced coatings against human cells have been tested, along with their antibacterial activity against S. aureus bacteria.ResultsA homogeneous coating was obtained with all the hydrogel formulations. Moreover, the coatings presented a hydrophilic behavior and micro-scale surface roughness. The addition of TA in the hydrogel formulations showed an increase in the release time compared to the normal GS-agarose hydrogels. Moreover, the GS released from these gels was able to significantly inhibit S. aureus growth compared to the GS-agarose hydrogels. The addition of CaCl2 to the gel formulation was able to significantly decrease cytotoxicity of the TA-modified hydrogels.ConclusionsDue to their surface properties, low cytotoxicity and high antibacterial effects, the hereby proposed gentamicin-loaded agarose-hydrogels provide new insight, and represent a promising approach for the surface modification of spinal implants, greatly impacting their application in the orthopedic surgical scenario.

On the Influence of Relative Humidity on the Contact Angle of a Water Droplet on a Silicon Wafer

2013 ◽  
Author(s):  
J. L. Perez-Diaz ◽  
M. A. Alvarez-Valenzuela ◽  
I. Valiente-Blanco ◽  
S. Jimenez-Lopez ◽  
M. Palacios-Cuesta ◽  
...  
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Relative Humidity ◽  
Silicon Wafer ◽  
Water Droplet ◽  
Measurement Techniques ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Wafer Surface ◽  
Free Energy Surface

Contact angle analysis of liquids on surfaces has been extensively used to evaluating solid surface free energy, surface tension, and surface wetting characteristics. Despite the great interest in the contact angle, reported measurements has shown a high variety, which is often related to different contact angle measurement techniques or substrate preparation and oxidation among others. In addition, it is well know, that surface tension and contact angle are modified with temperature. However, no attention has been paid to the influence of the relative humidity (RH) in surface tension or contact angle measurements. In a previous work, we have demonstrated that (for a constant temperature) surface tension on a suspended droplet decreases linearly with RH in the air. In this paper, contact angle of a water droplet on a silicon wafer surface is studied and its relationship with the relative humidity in the air investigated.

Study on Surface Modification of Polyethylene Terephthalate(PET) Film by RF-Ar/O2 Plasma Treatment

2012 ◽  
Vol 200 ◽  
pp. 194-198 ◽  
Author(s):  
Lin Kun Xie ◽  
Qin Ling Dai ◽  
Guan Ben Du ◽  
Qi Ping Deng ◽  
Gang Lian Liu
Keyword(s):  
Polyethylene Terephthalate ◽  
Photoelectron Spectroscopy ◽  
Film Surface ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Glow Discharge Plasma ◽  
Scanning Calorimetry ◽  
Static Contact ◽  
Before And After ◽  
Pet Film

The surface of polyethylene terephthalate film was modified using RF- Ar/ O2 glow discharge plasma under the condition of Ar and O2 flow amount of 1.9 and 1.2 (L/min) respectively and treatment power of 60 W. The changes of the properties of the film before and after modification were analyzed and characterized with static contact angle measurement, X-ray photoelectron spectroscopy(XPS), atomic force microscopy(AFM), differential scanning calorimetry(DSC). The results showed that the hydrophile of PET film was improved obviously after modification and formed some polar groups such as C-N, N-C=O, C=O, etc. on the film surface; The surface roughness was increased and appeared conical or globular protuberances; the thermal behaviors (mainly crystallinity) were changed after treatment by RF- Ar/O2 plasma.

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