Hi there again!
Eleven weeks passed and I have to admit that many things changed. So, I will be sharp and directly tell you what my project is about. For those who don’t remember, the title of my topic is “Enzyme strip assays with smartphone readout for acetylcholine esterase (AChE) inhibitors”. This long title can be separated in 3 parts. In detail:
- AChE inhibitors
Organophosphate (OPs) pesticides are widely used in agriculture in order to prevent crops from diseases and maximize productivity. OPs are inhibitors of AChE, a critical enzyme for nervous system. Communication between neurons is capable using neurotransmitters, chemical messages like acetylcholine. When a nerve cell gets the proper signal from the nervous system, it releases acetylcholine into its synapses with muscle cells. There, acetylcholine opens receptors on the muscle cells, permitting motion. However, the neurotransmitter must be cracked once the message is passed otherwise later signals would get mixed up. This is the duty of AChE, which stops the signal between a nerve and a muscle cell by decomposing acetylcholine. Malfunction of AChE could lead from weakness concerning mild cases to hypotension and even death in severe cases. In other words, consumption of OPs over a specific level harms your health.
- Enzyme strip assays
The precise and accurate detection of OPs in foodstuffs is a challenging task. It demands the use of high-cost and time-consuming techniques like Liquid and Gas Chromatography (LC & GC) by highly qualified scientists. Additionally, samples are randomly chosen and as a result only a few contaminated samples are detected. I quote some words from FoodSmartphone proposal in order to better understand current situation.
“According to the results of, e.g., veterinary drug residues in 2012 as reported to the European Food Safety Authority, 0.25% of the samples that went all this way were found to be non-compliant. Overall, this is an inefficient and expensive process. Despite all these efforts, we are still facing frequent food incidents and fraud issues. Based on the Rapid Alert system for Food and Feed (RASFF), 3157 original notifications (751 being ‘risk alerts’) were reported in 2014”.
Consequently, the development of an on-site pre-screening test, that will reduce the number of samples being analyzed with LC and GC, is an urgent need. In a previous blog, Vincent well defined what a screening test is.
“Screening = I have a very narrow range of compounds that can cause this test result”
In our case, AChE is irreversibly inhibited by OPs so the development of paper-based strips with immobilized enzyme is an affordable and quite sensitive solution. We already have some preliminary data that will be presented in RAFA 2017 symposium. There are many factors like matrix effects, sensitivity, stability that should be considered but the strips do have the potential to used and validated in food matrices.
- Smartphone readout
Right now, you may be confused on how the inhibition of the enzyme by OPs can be detected… So, there are many assays measuring the enzymatic activity of AChE. When the AChE is inhibited, the activity is decreased or even disappeared. Using chemistry the enzymatic activity can be related to color development.
Intense color on the paper strip -> high AChE activity and no OPs in the sample
Pale color on the paper strip -> low AChE activity due to OPs inhibition
Traditionally, the color development was evaluated using spectroscopy features like Absorbance, Fluorescence etc. in the lab. Nowadays, the measurement can be performed using our smartphone on the field. Many free applications have been already designed for the measurement of color using color spaces like RGB, HSV etc. If you don’t trust me, then log in to Google or Apple store and use a keyword like “color detection”. The result may be surprising. So, imagine yourself taking a snap of the paper strip and be informed through your FoodSmartphone application if your food is contaminated with pesticides or not…
I think that this was enough as in introduction to my PhD topic. There are also some other objectives within my project but I will further discuss it with you in my following blogs. Concerning my life as an ESR, the new academic year started on September. The internal rules of UCT define that each PhD candidate should attend and pass at least 3 courses. The variety of available course, from various fields, were great. I chose 5 courses. The 3 of them are kind of classic and needed for a food scientist. But the 2 others are really “special” for me.
“Effective scientific writing” is a course for PhD candidates dealing with, maybe, our ultimate goal: write and publish an original article. The tutor of the course is a native English speaker named Craig Alfraid Riddell. The course is interactive and will last 2 semesters. During this period, we are going to discuss how to write a scientific paper from Abstract to Conclusions. I have attended only 3 classes until now and I already feel much more confident to write. I definitely propose this kind of course to any PhD student.
Being the only foreigner in my group in UCT has forced me to hear all the time Czech. And this is helpful for learning this language. Nevertheless, the greatest boost is the Czech language courses for beginners that I attend. The course is for international PhD students of UCT who want to feet quicker and easier in Czech society. In general, the language is difficult but the hardest part for me is the pronunciation. As a Greek my accent is really soft and I am straggling say even the name of my country , “Řecko” :P. And here is a challenge to all of you. Try to say, with the appropriate Czech accent their famous Czech crystals or “český křišťál”, haha!
Another important fact during this 11 weeks was the award of my Master’s Diploma in Analytical Chemistry. In this way, I travelled back to Athens about 2 weeks ago. The visit in my home-city was the best gift for my graduation. I met again with my relatives, friends and colleagues and I am looking forward to see them again in Christmas.
My life in Prague is getting better. I feel more comfortable than in my previous blog. In the weekend, I am trying to explore the city. I have understood that every time something new is there for me. For example, last Sunday I visited Vitkov Hill. It’s a really historic place, where a battle took place during 1400 and also there stands the third largest equestrian statue in the world.
The lads in the lab are friendlier with me. Many times we arrange to drink some beers in order to relax from lab-work. I also have brought for them some Ouzo from Greece but we still try to fix the date. Czechs have really strict schedule, in Greece we usually arrange this kind of things fast. Anyway, I like them and I have to admit that I become more and more consistent in my everyday life because of them. Last but not least, the collaboration with my supervisor Prof. J. Hajslova is efficient and every meeting that we have is a pure earning of knowledge.
If you want to learn more for my progress and life until publishing my next blog you can follow me on twitter, @aris_tsagkaris. Also, I will be glad to see you in RAFA 2017 symposium and discuss the preliminary data of my poster. There you can meet also some other ESRs of FoodSmartphone project at RAFA Smart Lab on Wednesday and Thursday, November 8-9.
Thanks for reading my blog and hope to see you again,