Aptamer-Based Electrochemical Biosensing Platform for Detection of Hormonal Pollutants in Water
Poster Feb 25, 2015
Contreras Jimenez, G.; Eissa, S.; Ng, A.; Zourob, M.; Siaj, M.
Endocrine disrupters (EDs) are compounds that specifically interfere with the normal functions of the body’s endocrine system (system of glands for hormonal secretion) by causing adverse effects in both human and wildlife. Therefore, the routine, sensitive, reliable and cost effective detection methods for EDs are highly demanded.
In this work we present the selection and characterization of ssDNA aptamers that exhibit high affinity, specificity and sensitivity to progesterone (P4), 17b-estradiol (E2) and, norethisterone (NET). The aptamer selection was conducted by in vitro selections by incubating a huge ssDNA library of about 1.80x〖10〗^15 random sequences with the target analyte which has been previously immobilized on agarose beads. After certain cycles of selections, the enriched aptamers pool was cloned and sequenced. The dissociation constants (KD) of the selected aptamers were determined by fluorometry and by electrochemical impedance spectroscopy (EIS) methods. The KD values are in the low nanomolar range. Cross-reactivity tests for each aptamer demonstrated the high specificity to their target analyte. Additionally, circular dichroism (CD) spectroscopy measurements of the selected aptamers showed a remarkable conformational change upon binding the target analyte. The change in the conformation was exploited to design a biosensing platform to get a measurable signal after binding the specific analyte by following the redox process of a couple composed for [Fe(CN)6]3-/4-. For first time, an impedimetric aptasensor to detect progesterone was developed by yielding a limit of detection of 0.90ng/mL; for other analytes, the data will be presented and discussed in the programmed session of the conference.
We believe that the continuous selection of high affinity aptamers for other EDs and their integration in a biosensing platform will facilitate the routine monitoring of EDs in environment as well as clinical and medical diagnosis purposes.
Analysis of Extract Drying Criteria for Oil & Grease Method 1664A/BPoster
Analysis of Extract Drying Criteria for Oil & Grease Method 1664A/BREAD MORE
Fundamentals and Comparisons for Organic Sample Extract EvaporationPoster
Sample preparation is a key step in the analysis process
Parameters for evaporation and their impact on analysis have been discussed
Improvements in matching the sample to the evaporation device characteristics can help reduce variability and improve recovery
Examples for choosing a system based on sample volume, types of analytes, sample load, and initial investment considerations
Using Elemental Analysis For Discrimination Of Pinot Noir Wines From Six Different Districts In An AvaPoster
The determination of geographical origin of wine is gaining increased interest by researchers and federal agencies around the world, partially due to increased fraud with regards to place of origin labelling. For wine, multi-elemental profiling of macro, micro, and trace elements has been proposed for determination of authenticity. Commercial wines from different wineries in 5 different neighborhoods within one AVA show characteristic elemental fingerprints. Macro, micro and trace elements as well as elemental ratios contribute to the observed separation, indicating the involvement of multiple factors and underlying mechanisms, including location and soil composition, elemental uptake by vine and rootstock, viticulture and nutrient management, water sources, and small differences in the different wineries.READ MORE
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