Journal of Bioprocessing & Biotechniques

Due to the effective antimicrobial properties of silver nanoparticles (Ag NPs), these particles are receiving an extensive interest for applying in wide range of consumer products and water purification systems. Entering the Ag-based material in wastewater system can influence the biological cycle such as nitrogen. Denitrification as a part of nitrogen cycle is an effective biological process in wastewater systems which can be affected by Ag NPs. The objective of this research was to study the impact of Ag NPs on aerobic nitrate reduction. We showed that Rhizobium sp and Azotobacter sp isolates were able to reduce nitrate aerobically. Adding 0.2 ppm of Ag NPs in culture medium of Azotobacter PHB+ enhanced the of the nitrate reduction activity about 20% and Ag NPs at this concentration has no significant effect on the nitrate reduction activity of periplasmic extracts of the selected isolates in aerobic conditions. Thus, entering certain ation of Ag NPs in environments has no significant impact on microbial aerobic denitrification as an important part of nitrogen cycle.

Bone tissue has a composite nature given by a highly complex and well-harmonized structure of organic and inorganic components on the microscale, macroscale and nanoscale. Thus, biodegradable composite scaffolds made of poly (ε-caprolactone) urethane (PCL_PUR) porous matrix and calcium carbonate (CaCO3) were developed and studied for bone tissue engineering. The aim of this work was to examine the structure of new polyurethane/calcite composites. Micro-computer tomography (μ-CT) and image analysis enabled 3D visualization and quantification of the porosity, wall thickness and internal pore size distribution. The fabricated porous polyurethane composites exhibited porosity >70% with a pore size not exceeding 450 μm and wall thickness about of 50 μm in size. The mechanical properties of the foams were evaluated using Dynamic Mechanical Analysis (DMA). In-vitro bioactivity tests in simulated body fluid (SBF) were carried out and the marker of bioactivity, e.g. formation of surface bone-like apatite layers upon immersion in SBF, was investigated. Our results indicated that PUR/calcite scaffolds were more activity then PUR scaffolds and possessed the function to enhance cell proliferation and differentiation, and might be used as bone tissue engineering materials.

The fabrication and the performance response characteristics of a novel sensitive, selective, simple, and rapid sensor for the determination of Clopidogrel bisulphate (CLO-H₂SO₄) were described. The sensing modified carbon paste sensor comprised of an ion-pair based on Clopidogrel with silico tungastate (CLO-ST) where this study included: composition, usable pH range, response time and temperature. The sensorex hibiteda wide linear dynamic concentration ranging from 1.00x10−7-1.00x10−2 and the usable pH ranges from 1.2-4.8 with the response time ranging from (5-8 sec) which is much faster compared to liquid ISEs with a detection limit equals 0.34 nM. The selectivity of the sensor (CLOH₂SO₄) was applied with respect to a many of organic and inorganic cations, amino acids and sugars. The application of the sensor (CLO-H₂SO₄) for its determination was utilized in bulk powder, Plavix Tablet, human (serum-urine) and monitoring Plavix tablet dissolution rates using calibration curve, standard addition, and the potentiometric titration methods. The obtained results were statistically analyzed in both accuracy and precision and were compared using the US pharmacopeia method where there is no significant difference was observed.

Carbon dioxide capture and utilization (CCU), a concept of turning a greenhouse gas into a useful feedstock, is gaining much attention in recent years. Increasing CO₂ emission into the atmosphere, from fossil fuel combustion and other anthropogenic activities, has forced us to source for more sustainable and economical routes of chemical syntheses. Instead of developing new chemical catalysts and CO₂-based chemistry, we should perhaps learn from Nature. Over the past billions of years, Nature has evolved sophisticated mechanisms for carbon concentration, fixation and utilization, manifested through autotrophy. Many organisms, such as photosynthetic and chemolithoautotrophic organisms, display excellent ability in assimilating CO₂ and converting it into complex molecules. Through the use of enabling technologies (e.g., genetic engineering and protein engineering), the range of CO₂-derived bio-based products is expanding at a rapid pace. Chemicals that can be synthesized biologically include bio-plastics, bio-alcohols, biodiesel, to name a few. Continued research on multiple fronts and closed collaboration between scientists and engineers are required to further develop biological systems into viable chemical production platforms.

In this work, our choice fell on the exploitation of rubber aggregates from used tires. In this context, an experimental study was conducted to provide more data on the effect of rubber aggregates on the thermophysical properties of self-consolidating concrete (SCC). To this end , four sets of rectangular specimens were prepared by varying the proportion of the rubber aggregates with percentages of 0%, 10%, 20% and 30% of the volume of gravel .Tests on hardened self-consolidating concrete rubber SCCR included measuring the thermal conductivity and the thermal diffusivity by the method of the boxes at steady and determining the specific heat . The results showed that the thermal conductivity and thermal diffusivity were decreased according to the increase of the percentage of rubber aggregates. This decrease was significantly improved thermal performance of the SCCR.

DNA extraction methods such as plasmid minipreps, gel, and PCR purifications, are indispensable techniques for genetic manipulations. There are numerous factors that contribute to the efficiency of these processes, which determine the success of complex downstream molecular analytics and diagnostic tests. To study and optimize these factors, we compared our own proprietary buffers to commercially available column-based kits, utilizing their spin columns and protocols. Through systematic substitution of the buffers in the kits with our own proprietary buffers, we selected the highest DNA yielding buffer recipes. Further analysis of the differences between the buffers showed that high concentrations and presence of certain chaotropic agents and cations are necessary for good plasmid miniprep, gel extraction, and PCR purification kits.