Assessment Of Surfactants Research Articles

Assessment of surfactants on performance of molecularly imprinted polymer toward adsorption of pharmaceutical

Double imprinting process is fundamental to improvements in the adsorptive capacity of the molecularly imprinted polymers (MIP), but the effect of the surfactant type on adsorptive properties of the double-imprinted polymers are poorly understood. Thus, MIP to potassium diclofenac (PD) were developed and evaluated for their adsorbent properties. Polymers were characterized by infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetry (TGA) and textural properties. Kinetic studies performed at pH 6 showed the best fit (R² = 0.999) using a pseudo-second-order model. Adsorptive capacities toward PD of polymer using benzalkonium chloride (BC), sodium dodecylsulfate (SDS) and Triton X-100 (TT-X-100) were found to be 1.82 mg g−1, 1.12 mg g−1 and 0.51 mg g−1, respectively. MIP presented adsorptive capacity of 0.42 mg g−1, while for no template (NIP) 0.35 mg g−1. Equilibrium adsorption data were best fitted with Freundlich isotherm for MIP-SDS, single-site Langmuir-Freundlich for MIP and dual-site for MIP-BC, MIP-TT-X-100 and NIP. Selectivity study proved that all the polymers had better binding capacity towards PD, with good selectivity and affinity over other drugs. This study showed that the addition of surfactant influenced the adsorbent properties of the material, being the MIP-BC the polymer with larger pore size, enhancing consequently the mass transfer of the DP toward the sorbent sites, so it presented better adsorption capacity.

Application of axisymmetric drop shape analysis and brewster angle microscopy for assessment of clinical samples from prematurely born infants with NRDS

Axisymmetric drop shape analysis (ADSA) is a powerful technique for surface tension measurement of a pendant drop, requiring only 50 microliters of the tested clinical sample. In addition, Brewster angle microscopy (BAM) is a well-established and useful method for visualization of ultra-thin surface films, such as Langmuir monolayers, on air-water interface. In the present study we analysed the surface properties of gastric aspirates (GAs) from prematurely born infants with neonatal respiratory distress syndrome (NRDS) and healthy full term infants with regard to find an approachable method for assessment of surfactant maturity at birth. The measurement of dynamic surface characteristics of GA by ADSA showed significantly higher mean values of the minimal surface tension in the premature infants as compared to the full term babies. This parameter proves to be the most reliable parameter for lung maturity assessment. In addition, the hysteresis curves of the surface tension vs. drop surface area indicated more stable surface behavior of alveolar surfactant from healthy children, as compared to the NRDS infants. The morphology of the monolayers composed of GAs also showed considerable differences between the samples from both groups studied. In conclusion, ADSA and BAM methods could be used into the clinical practice for rapid and sensitive surfactant's assessment in premature infants with regard to administration of exogenous surfactant.

Investigação Bioquímica e Biofísica do Surfactante em Aspirado Gástrico Neonatal ao Nascimento

The optimal approach to detection of surfactant deficiency in the prematurely born infants at birth remains unclear and the decision to apply exogenous surfactant is based mainly on the development of clinical and radiological signs of neonatal respiratory distress syndrome (NRDS). We studied the biochemical and biophysical properties of gastric aspirates (GA) from prematurely born infants with NRDS and healthy full term infants with an aim to find an approachable method for assessment of surfactant maturity at birth. Forty-seven newborn infants divided into two groups were enrolled in the study. The first group comprised 34 healthy infants born at term (after 37 weeks of gestation). The second group included 13 premature infants (aged from 26 to 32 weeks of gestation) developing clinical signs of NRDS for which they were treated by assisted ventilation and exogenous surfactant. A biochemical analysis of the protein and lipid content of GA collected at birth was performed. The fatty acid composition of the GA samples was determined by Gas Chromatography-Mass Selective Detector (GS-MSD) analysis. The surface characteristics (equilibrium, maximal and minimal surface tension values) of the GA samples were measured by using the pending drop method. Data were compared between the groups by using Student's t test or Mann-Whitney analysis. Values were considered significantly different if the p value was = 0.05. The mean phospholipids' concentration in GA of the premature infants was lower (295.7 µg / ml vs. 374.5 µg / ml) than in the term infants and the mean protein content was less in GA of the premature babies than the term newborns (574.5 µg / ml vs. 641.5 µg / ml). The measurement of dynamic surface characteristics of GA showed significantly higher mean values of the minimal surface tension (γmin) in the premature infants - 20.5 m / Nm compared to the term babies - 12.3 mN/m (p < 0,01). There was no difference between the equilibrium surface tensions (38 mN/m vs. 38 mN/m) of both groups; The mean values of maximal surface tension (?max) in GA did not differ significantly between the groups (50.1 mN/m vs. 48.5 mN/m). Our findings revealed lower phospholipids' and protein concentrations in the GA at birth from premature infants as compared to the healthy term infants. The dynamic surface characteristics of GA had significant differences between the two groups, the minimal surface tension being the most important parameter for evaluation of surfactant maturity. It could be used in the clinical practice for fast surfactant's assessment in the premature infants in regard to administration of exogenous surfactant.

Analysis of Bronchoalveolar Lavage Fluid Adhering to Lung Surfactant

Nickel oxide with two different particle sizes, micron size (NiO) and submicron size (nNiOm), as well as crystalline silica as a positive control and titanium dioxide as a negative control, were intratracheally instilled in rats and the phospholipid concentration and the protein concentration and surface tension of bronchoalveolar lavage fluid (BALF), which are used in surfactant assessment, were measured to see if they could be effective biomarkers in toxicity assessment. The results showed that the NiO instilled group showed no significant difference compared to the control group throughout the observation period. In contrast, a significant difference was found in the nNiOm instilled group compared to the control group throughout the observation period. Moreover, a significant difference was found in the crystalline silica instilled group for each measurement compared to the control group while for the titanium dioxide group, almost no significant difference was found. These results indicate that submicronsized particles of nickel oxide with smaller median diameters potentially have a stronger biological effect than micron size particles. They also indicate that screening can be done by measuring the phospholipid concentration and the protein concentration and surface tension of BALF.

Bubble clicking: Oscillations induced by the lung surfactant

The bubble clicking test is a promising technique for rapid lung surfactant assessment. It is based on observing bubble oscillations when a sufficiently high concentration of the lung surfactant is present in the studied sample. This paper presents the theoretical conditions for bubble clicking to occur: (a) the possible coexistence of two states of the bubble having the same volume but different surface tensions and shapes and (b) sufficiently small Gibbs energy difference between these two states. It is shown that these conditions may indeed be fulfilled when the surface tension is sufficiently low (sufficiently high surfactant concentration), within a specified bubble volume range. The present theoretical conclusions qualitatively agree with known experimental observations.

Aquatic hazard assessment of surfactants: How much information is needed to judge environmental safety?

Aquatic hazard assessment of surfactants: How much information is needed to judge environmental safety?

Automated Rapid Assessment of Surfactant and Fetal Lung Maturity

This study reports predictions for clinical respiratory distress syndrome (RDS) by means of a rapid test for fetal lung maturity based on fluorescence polarization of a dye (PCI 6) that partitions between surfactant and albumin in amniotic fluid. The test is completed in approximately 30 minutes and requires collection of a specimen volume of only 0.5 mL amniotic fluid. Results are reported as mg surfactantlg albumin (SIA value) equivalence. Ninety-three infants were delivered within 2 days of a collection of amniotic fluid and were followed up for the presence or absence of symptoms consistent with RDS. Ten infants, two of whom had anomalies, developed RDS. With a threshold of <50 mg/g equivalence to indicate probable occurrence of symptoms consistent with RDS, the SI A value had a sensitivity of 90% for predicting RDS, with a specificity of 87%, a positive predictive value of 45%, and a negative predictive value of 99%. This was comparable to using the lecithin-tosphingomyelin ratio of <2.0, which had a sensitivity of 80%, a specificity of 93%, and positive and negative predictive values of 57% and 98%, respectively. The clinical predictions based on the absence of phosphatidylglycerol were 90% sensitivity, 79% specificity, and 35% and 98% positive and negative predictive values, respectively. SI A values obtained for specimens that were frozen and thawed correlated well with results from nonfrozen specimens. Satisfactory S/A values were obtained with specimens of amniotic fluid that were collected from vaginal pools. Loss of fluorescence polarization because of partition of PCI 6 between albumin and surfactants represents an integrated effect of the surfactants and provides an additional assessment of lung maturity comparable to currently accepted tests. The ligand-based assay requires only a small volume of specimen, is rapid, and can be standardized between institutions. These features indicate that the PCI 6-based assay provides an alternative assessment of lung maturity to currently existing methodologies, or when little specimen is available or there is an urgent need for results.