The Place of Electrospinning in Separation Science and Biomedical Engineering

Electrospunnanofibers have found myriad of applications from separation science to clinical translation. Electrospunnanofiber scaffolds have the benefits of unique properties such as high surface area to volume ratio, interfibrous pore sizes, strong penetrability, great deal of active sites for adsorption, excellent stability, better targeting, minimum toxicity, high drug-loading capacity, exceptional mechanical properties, flexibility in surface functionality, ease of encapsulation of drugs and bioactive compounds, suitability for thermos-liable drugs, enhanced cellular interactions, and protein absorption to facilitate binding sites for cell receptors. In the field of separation science, electrospunnanofiber scaffolds have extensively served as sorbent material for solid phase extraction techniques mainly due to the need to improve sorptive capacity and analyte selectivity. Given that almost all of the human tissues and organs are deposited in nanofibrous forms or structures, electrospunnanofibers/nanocomposites are currently being investigated for potential clinical applications. It is noteworthy that the nanofiber fabrication technique and the material integrity are key components to obtaining clinically relevant nanofibers. Owing to the significance of fiber arrangement to nanofiber performance, electrospinning has a leading edge over other nanofiber fabrication techniques due to the ease of controlling fiber orientation, despite the inherent advantages of other conventional nanofiber fabrication techniques. The current review highlights the superb qualities of electrospunnanofibers, their various methods of fabrication, and their various applications especially in separation science and clinically. We further provided an overview of the electrospinning principles, types of electrospinning, parameters that affect the nanofibers fabrication via electrospinning, challenges, and the future directions. The advent of robotics-assisted electrospinning technique offers new opportunities for the traditional biofabrication in higher accuracy and controllability and hence will certainly drive nanotechnology from laboratory/industry toward patient care in the near future

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) in petroleum contaminated soils

Polycyclic aromatic hydrocarbons are a class of potentially hazardous chemicals of environmental and health concern. PAHs are one of the most prevalent groups of contaminants found in soil. Biodegradation of complex hydrocarbon usually requires the cooperation of more than single specie. In this research biotreatment of PAH (phenanthrene) was studied in a solidphase reactor using indigenous bacteria isolated from two petroleum contaminated sites in Iran, (i.e., Tehran refinery site with clayey-sand soil composition and Bushehr oil zone with silty-sand soil composotion). Phenanthrene (C14H10) was made in three rates (100, 500, and 1000 mg/kg of soil) synthetically and was conducted with two bacterial mixed cultures for a period of 20 weeks. Highest removal (more than 85 ) of phenanthrene with rates of 100, 500 and 1000 mg/kg in clayey-sand soil with BMTRS (Bacterial Mix of Tehran Refinery Site) consortium was achieved within 3, 5 and 14 weeks, respectively as for silty-sand soil composition with BMBOZ (Bacterial Mix of Bushehr Oil Zone) consortium was achieved within 10, 17, and 19 weeks, respectively. Results for phenanthrene biotreatment in solid phase reactor revealed a significance relationship between concentration and type of microbial consortium with the removal efficiency of phenanthrene over the time (P value<0.001). Furthermore, there was a significant relationship between soil type with removal efficiency of phenanthrene over the time (P value=0.022). That means the bioremediation of the lower concentrations of phenanthrene needs shorter time compared with the higher concentrations. Microbial analysis using confirmative series tests and analytical profile index (API) kit tests showed the Pseudomonas fluorescence, Serratia liquefaciens, Bacillus and Micrococcus strains as dominant bacteria in the mixed cultures

A screen for Benzo(a)pyrene in fish samples from crude oil polluted environments

Several studies have shown that exposure to Benzo(a)pyrene increases the risk of cancer. In this study several fish samples from Niger the Delta region of Nigeria were screened for the presence of Benzo(a)pyrene. The study was carried out using Gas chromatograph coupled to a mass spectrometry detector. Benzo(a)pyrenes in the samples were identified through both retention time match with authentic standards and simultaneous maximization of several major ions from GC/MS data. Perylene-d12 was used as the internal standard for quantitation. Concentration of benzo(a)pyrene in the samples ranged from 1.47 to 10.53 μg/kg which is more than WHO recommended maximum allowable concentration. Therefore this study concludes that the population is at an elevated risk of cancer of occurrence. © 2008 Science Publications

Phenanthrene contaminated soil biotreatment using slurry phase bioreactor

Problem Statement: Polycyclic Aromatic Hydrocarbons (PAHs) are suspected toxins that accumulate in soils and sediments due to their insolubility in water and lack of volatility. Slurry-phase biological treatment is one of the innovative technologies that involve the controlled treatment of excavated soil in a bioreactor. Due to highly soil contamination from petroleum compounds in crude oil extraction and also oil refinery sites in Iran, this research was designed based on slurry phase biotreatment to find out a solution to decontamination of oil compounds polluted sites. Approach: Soil samples were collected from Tehran oil refinery site and Bushehr oil zones. Two compositions of soils (clay and silt) were selected for slurry biotreatment experiment. Soil samples were contaminated with three rates of phenanthrene (a 3 ring PAH), 100, 500 and 1000 mg kg ?1 and mixed with distilled water in solid concentration of 30 by weight after washing out with strong solvent (hexane) and putting in to the oven. Bacterial consortium was revived in culture medium which consisted of Mineral Salt Medium (MSM) based on phenanthrene concentrations and ratio of C/N/P in the range of 100/10/2. Prepared soil samples were mixed with distilled water, nutrient and bacterial consortium together in the 250 mL glass Erlenmeyer and putted in the shaker incubator with 200 rpm revolutions and 25°C for 7 weeks (45 days). Samples were analyzed for residual phenanthrene, bacterial population every week. For statistical analysis, general linear model with repeated measures (type III) analysis was applied. Results: The concentration of 100 mg L?l of phenanthrene in clayey and silty soils reached to non detectable limit after 5 and 6 weeks, respectively. While concentration of 500 mg L?l of phenanthrene both in clayey and silty soils reached to non detectable limit after 6 weeks. But concentration of 1000 mg L?l both in clayey and silty soil samples has not met this limitation after 7 weeks. Due to presence of Pseudomonas strains in clayey soil samples and their ability in breaking down of benzene rings, the removal efficiency of phenanthrene in our slurry bioreactor in clayey soil was a little more than silty soil samples over time. There was a significance relationship between initial concentrations of phenanthrene and type of soil with time of biotreatment (p<0.001). Conclusion: Therefore, this technology may be applied to remediation of small foot print oil contaminated sites, e.g., gas station, oil extraction and refinery sites in Iran, in the case of urgency. Thus this study concludes that the remediation of phenanthrene with concentration up to 1000 mg kg?1 in the oil contaminated sites can be removed to the acceptable limits using slurry based system. © 2009 Science Publications

APPLICATION OF POLYNUCLEAR AROMATIC HYDROCARBONS IN CHEMICAL FINGERPRINTING: THE NIGER DELTA CASE STUDY

Chemical fingerprinting is an aspect of environmental forensic investigation which involves chemical analysis of contaminants and associated chemicals to provide source specific information. Polynuclear Aromatic Hydrocarbons (PAHs) in the environment have 3 categories of sources namely petrogenic, pyrogenic and biogenic sources. Petrogenic PAHs are generated from geochemical alterations of organic mater. Pyrogenic PAHs originate when organic matter is incompletely combusted. Biogenic originate as a result of oxidation of microbial or plant derived compounds in older and deeper sediments. PAHs fingerprinting involves the determination of a number of quantitative diagnostic ratios of source specific marker PAH compounds. These quantitative diagnostic ratios may be used to distinguish petrogenic PAHs including phenanthrene/anthracene; benz(a)anthracene/chrysene; flouranthene/pyrene; phenanthrene/(phenanthrene+anthracene) and indeno(1,2,3-cd) pyrene/indeno (1,2,3-cd) pyrene + benzo (ghi) perylene from other sources. In this research over 40 environmental samples from the Niger Delta region were subjected to chemical fingerprinting employing some of the quantitative diagnostic ratios above with the aim of ascertaining the precise nature and source the contaminants. It was found that the PAHs contamination in the Niger Delta is not only emanating from petrogenic sources but other sources contribute significantly

Heavy metals content in the stem bark of Detarium microcarpum determined by atomic absorption spectrophotometer

Detarium microcarpum is a member of the Caesalpinaceae sub-family and Leguminosae family of the flowering plants. Beneficial effects of natural products in healthcare delivery in Africa cannot be over emphasized. One of the main concerns with these plant products is the level of heavy metals. The heavy metal analysis was carried out on the stem bark of D. microcarpum using an atomic absorption spectrophotometer (AAS). The heavy metals screened for include: lead, chromium, manganese, zinc and iron. The levels of manganese, zinc and iron were 13.91, 4.89 and 21.89 mg/L respectively. These heavy metals were found to be present in the stem bark of D. microcarpum at concentration levels higher than tolerable upper intake limits. There is therefore some health implication when ingested. Lead and chromium were not detected in the study.Key words: Detarium microcarpum, metal, contaminants

Decontamination of Petroleum Hydrocarbon Contaminated Soils using Bioventing Technique

The fate of petroleum hydrocarbons in nature is of great environmental concern due to their toxic, mutagenic, and carcinogenic properties. A major decomposition process of petroleum hydrocarbons in the environment is microbial degradation. Polycyclic aromatic hydrocarbons (PAHs) are one of the most prevalent groups of contaminants found in soil. This research was carried out on phenanthrene (a 3-ring PAH) polluted soils decontamination in a solid phase reactor using synthetic contaminated soils with attribution of indigenous bacteria isolated from petroleum contaminated sites in Iran. Polluted samples was made of phenanthrene with three rates (100, 500, and 1000 mg/kg of soil) synthetically and was conducted with two bacterial consortium for a period of around twenty weeks. Ultrasonic machine and HPLC was applied for extraction and analysis of phenanthrene from contaminated soil samples. Microbial analyses were carried out using confirmative series tests, analytical profile index (API) kit tests and PCR. Results for phenanthrene biotreatment in solid phase revealed a significance relationship between concentration of phenanthrene and type of microbial consortium and type of soil with the removal efficiency over time of bioremediation (P value<0.001). According to the microbial analysis using complete amplified PCR and DNA extraction, among of Pseudomonas fluorescence, Serratia liquefaciens, Bacillus and Micrococcus strains that were as dominant bacterial consortiums in the contaminated soil samples, Pseudomonas fluorescence (pudita) was responsible to higher degree degradation of phenanthrene. Results showed that the microbial decomposition of the lower concentrations of phenanthrene needs shorter time compared with the higher concentrations. We can concluded that, the microbial treatment of oil hydrocarbons contaminated soils may considered as a feasible option in petroleum polluted sites in Iran