Contact Angle of Nepenthes alata Slippery Zone: Results from Measurement and Model Analysis

The slippery zone of Nepenthes alata depends on its highly evolved morphology and structure to show remarkable superhydrophobicity, which has gradually become a biomimetic prototype for developing superhydrophobic materials. However, the mechanism governing this phenomenon has not been fully revealed through model analysis. In this paper, the superhydrophobicity of slippery zone is studied by contact angle measurement, morphology/structure examination and model analysis. The slippery zone causes ultrapure water droplet to produce a considerably high contact angle (155.11–158.30°), and has a micro-nano scale hierarchical structures consisting of lunate cells and wax coverings. According to the Cassie-Baxter equation and a self-defined infiltration coefficient, a model was established to analyze the effect of structure characteristic on the contact angle. Analysis result showed that the calculated contact angle (154.67–159.49°) was highly consistent with the measured contact angle, indicating that the established model can quantitatively characterize the relationship between the contact angle and the structure characteristic. Our study provides some evidences to further reveal the superhydrophobic mechanism of Nepenthes alata slippery zone, as well as inspires the biomimetic development of superhydrophobic surfaces.

Application of an Ultrashort-pulsed Laser for Generation of Super-hydrophobic Surfaces

Hydrophobic surfaces have gained a vast attention in different fields of biomedical applications over the last few years. Laser treatment has been shown as a promising technology for the generation of functional, inter alia, superhydrophobic surfaces. In this study a picosecond Yb-YAG laser was assigned for the generation of superhydrophobic characteristics on a steel alloy with application in surgical instrumentation. Regarding the ablation energy threshold of about 6 μJ for the given pulse width and laser beam characteristics and by assigning a suitable combination of microstructure kinematics and laser processing conditions a persistent hierarchical pattern is mapped over the laser-radiated surfaces. The average measured contact angle on the laserradiated surfaces was about 150°, which indicates their superhydrophobic properties.

Effects of Sucrose Palmitate on the Physico-Chemical and Mucoadhesive Properties of Buccal Films

In our current research, sucrose palmitate (SP) was applied as a possible permeation enhancer for buccal use. This route of administration is a novelty as there is no literature on the use of SP in buccal mucoadhesive films. Films containing SP were prepared at different temperatures, with different concentrations of SP and different lengths of hydroxypropyl methylcellulose (HPMC) chains. The mechanical, structural, and in vitro mucoadhesive properties of films containing SP were investigated. Tensile strength and mucoadhesive force were measured with a device and software developed in our Institute. Positron annihilation lifetime spectroscopy (PALS) and X-ray powder diffractometry (XRPD) were applied for the structure analysis of the films. Mucoadhesive work was calculated in two ways: from the measured contact angle and compared with direct mucoadhesive work, which measured mucoadhesive force, which is direct mucoadhesion work. These results correlate linearly with a correlation coefficient of 0.98. It is also novel because it is a new method for the determination of mucoadhesive work.

Improvement of Hydrophilic Properties on Electrospun Polyacrylonitrile Fabrics Surface by Plasma Treatment

Electrospun polyacrylonitrile (PAN) fabrics were prepared by electrospinning with 7%w/v concentration to dissolve in dimethylformamide (DMF) and spinning time 12 h. Radio frequency inductively couple plasma (RF-ICP) at 13.56 MHz were used to improve PAN fabrics surface by O2 gas in plasma treatment that became to hydrophilic properties of PAN fabrics surface. Physical properties were determined by scanning electron microscopy (SEM) and contact angle measurement which found that characterized on PAN fabrics surface after plasma treatment with increased treated time had been damaged on these fabrics surface which measured contact angle measurement with water were range 29.3 to 74.7. Chemical properties were analysed by fourier transform infrared spectroscopy (FTIR) that had been found peak intensities of aliphatic C-H band at 1450 and 2930 cm-1 and peak intensities of cyclic C=O bands at 1732 cm-1 and peak intensities of saturated nitriles at 2243 cm-1 and peak intensities of hydroxyl O-H band at 3600-3650 cm-1.

Work of adhesion of respiratory tract mucus

A method was devised to measure the work of adhesion (WA) to a substrate of mucus, a viscoelastic gel, from the measured contact angle of glycerol on a mucus substrate and the known physical properties of a Teflon surface. Fifteen sputum samples from cystic fibrosis (CF) patients were compared with 25 mucus samples from canine tracheal pouches (CP), studied in the hydrated and partially dehydrated states. Apparent viscosity (eta A) and recoverable shear strain (SR) were measured by fluxgate magnetometry, and water content was inferred from vapor pressure osmometry. Na+, K+, and Ca2+ concentrations were measured with specific ion electrodes and Cl- with a chloridimeter. The Cl- concentration of the CP mucus was inversely proportional to its osmolality, and the Cl- concentration of the CP mucus was 102.5 +/- 1.6 meq/l compared with 55.6 +/- 2.5 meq/l for CF sputum. When CP mucus osmolality was increased from 316.0 +/- 5.5 to 430.0 +/- 7.5 mosmol/kg, WA increased from 25.1 +/- 1.8 to 31.1 +/- 1.2 ergs/cm2 and eta A increased from 391 +/- 55 to 622 +/- 121 P, respectively. CF sputum WA was 30.2 +/- 0.6 ergs/cm2, eta A was 1,110 +/- 316 P, and osmolality was 466.0 +/- 14.0 mosmol/kg. The increased WA and eta A of mucus in CF patients may thus be dependent on the hydration of mucus, which is related to the documented Cl- transport defect.