Development of QCM Biosensor with Specific Cow Milk Protein Antibody for Candidate Milk Adulteration Detection

Adulteration of goat milk is usually done using cow's milk product. Cow milk is used as it is widely available and its price is cheaper compared to goat milk. This paper shows a development of candidate tools for milk adulteration using cow milk. A quartz crystal microbalance immunosensor was developed using commercial crystal resonator and polyclonal antibody specific to cow milk protein. A specific protein at 208 KDa is found only in cow milk and does not exist in goat milk. The existence of this protein can be used as an indicator of cow milk content in a target solution. To detect the PSS 208 kDa protein, antibody specific to the PSS 208 was developed. The purified antibody was immobilized on top of the sensor surface on a polystyrene layer. The fraction of the immobilized antibody on the sensor was found at 1.5% of the given antibody. Using a static reaction cell, the developed immunosensor could detect the specific cow milk protein in buffer solution. The detection limit is 1 ppm. A linear relationship between frequency change and specific protein of cow milk concentration is found from a concentration of 1 ppm to 120 ppm

Design of Low Noise Micro Liter Syringe Pump for Quartz Crystal Microbalance Sensor

An injection pump was a critical aspect in the used of Quartz Crystal Microbalance (QCM) biosensor or chemical sensor in liquid. It is required that the pump should have variable speed and doesn't introduce pressure noise to the QCM sensor. In this work, the pump was developed using a micro stepper motor with a microliter syringe. The mechanical transmission transforms the rotational displacement of the motor into a translational displacement of the syringe. The flow rate of the injection pump could affect the signal pattern indicated by a signal spike or instability of the sensor resonance frequency. The developed system successfully minimized the spike signal and improved the stability of the sensor resonance by the used of the microliter syringe pump with optimizing the reaction chamber of the QCM sensor. The flow rate of the pump can be controlled with a minimum speed of 0.7 microliter per second for water. At low flow rate, there was a negligible or none of the spike signal observed during the injection and ejection of the liquid. However, at a high flow rate, few signal spikes may be observed

Biossensores para detecção de resíduos de antibióticos em leite de bovinos: contextualização

Pesquisa sem auxílio de agências de fomentoTrabalho de Conclusão de Curso (Graduação)Os biossensores proporcionam análises com alta sensibilidade e seletividade requeridas em comparação com métodos tradicionais, associadas à portabilidade e fácil manuseio. Estes dispositivos possuem uma biomolécula imobilizada na superfície do transdutor, com intuito de detectar alterações geradas por uma reação ou interação a nível bioquímico. A aplicação desses dispositivos em diversos campos de estudos, resulta em uma gama de trabalhos e tecnologias desenvolvidas. Uma grande porção desse mercado está concentrado na agroindústria, principalmente no setor da pecuária leiteira, devido ao uso indiscriminado de antibióticos para tratamento de mastites e na terapia da vaca seca. Estima-se que o consumo anual de antibióticos somente para esse setor seja maior que 63.000 toneladas. Portanto, este trabalho apresenta uma revisão bibliográfica dos principais biossensores aplicados à pecuária leiteira, visando discutir a cerca das implicações do uso de antibiótico em bovinos leiteiros e suas consequências em humanos das principais moléculas avaliadas nas provas de conceito. Para efetuar as análises, foram selecionados trabalhos das plataformas PubMed e Periódico CAPES. A escrita foi orientada para descrever as propriedades dos biossensores, em tabelas. Quanto aos artigos, as moléculas de canamicina e cloranfenicol apresentaram maiores quantidades de trabalhos, 18 e 9 respectivamente. Apesar da revisão, o mercado carece de biossensores comerciais, sendo apenas 67 trabalhos listados nos últimos 10 anos com aplicação em amostras de leite de bovinos, resultando no uso de 100% de imunoensaios tipo ELISA e Fluxo Lateral

Οπτικοί ανοσοαισθητήρες για την ταυτόχρονη ανίχνευση αλλεργιογόνων ουσιών σε τρόφιμα

Η τροφική αλλεργία επηρεάζει μεγάλο ποσοστό των ανθρώπων παγκοσμίως. Για το λόγο αυτό, διεθνείς οργανισμοί έχουν θεσπίσει κανόνες τόσο για τον έλεγχο παρουσίας αλλεργιογόνων όσο και για την υποχρεωτική αναγραφή τους στις ετικέτες των επεξεργασμένων προϊόντων εκ μέρους των βιομηχανιών τροφίμων. Για την αποφυγή ανεπιθύμητης επιμόλυνσης των τροφίμων με αλλεργιογόνα λόγω της χρήσης κοινών γραμμών παραγωγής για διαφορετικά προϊόντα είναι απαραίτητος ο έλεγχος παρουσίας αλλεργιογόνων τόσο στο νερό καθαρισμού/ έκπλυσης των σωληνώσεων και μηχανών όσο και στα ίδια τα τελικά προϊόντα και τις πρώτες ύλες που χρησιμοποιούνται. Σκοπός της παρούσας διδακτορικής διατριβής ήταν η ανάπτυξη μεθόδου για τον ταυτόχρονο προσδιορισμό της κ-καζεΐνης, της πρωτεΐνης φιστικιού, της πρωτεΐνης σόγιας και της γλιαδίνης σε νερό έκπλυσης σωληνώσεων από βιομηχανίες τροφίμων σε πραγματικό χρόνο, μέσω οπτικού ανοσοαισθητήρα χωρίς τη χρήση ιχνηθετών. Ο οπτικός ανοσοαισθητήρας που χρησιμοποιήθηκε ήταν πλήρως ολοκληρωμένος σε ψηφίδες πυριτίου και περιλάμβανε συστοιχία δέκα συμβολομέτρων Mach-Zehnder (MZI) καθώς και τις αντίστοιχες οπτικές πηγές παρέχοντας τη δυνατότητα ταυτόχρονης ανίχνευσης πολλών αναλυτών στο ίδιο δείγμα. Για την επίτευξη του στόχου, αναπτύχθηκαν και βελτιστοποιήθηκαν ανοσοενζυμικοί προσδιορισμοί (ELISA) για όλα τα στοχευόμενα αλλεργιογόνα καθώς και μέθοδοι ανίχνευσης μονού και πολλαπλών αναλυτών με τον αισθητήρα. Οι αναπτυχθείσες μέθοδοι ταυτόχρονου προσδιορισμού των αλλεργιογόνων ήταν ταχείες (6,5 min) και ακριβείς με όρια ανίχνευσης εφάμιλλα ή χαμηλότερα των εμπορικά διαθέσιμων μεθόδων που χρησιμοποιούνται από τις βιομηχανίες. Η δυνατότητα εφαρμογής του αισθητήρα σε πραγματικές συνθήκες αξιολογήθηκε μέσω ανάλυσης δειγμάτων νερού έκπλυσης σωληνώσεων γαλακτοβιομηχανίας και διαπιστώθηκε ότι οι τιμές που προσδιορίστηκαν ήταν σε καλή συμφωνία με αυτές που ελήφθησαν τόσο με τις μεθόδους ELISA που αναπτύχθηκαν όσο και από εξωτερικά διεθνή εργαστήρια. Επιπλέον, ο αισθητήρας αξιοποιήθηκε για την ανίχνευση νοθείας κατσικίσιου γάλακτος με αγελαδινό, μέσω προσδιορισμού βοείου κ-καζεΐνης, και παρείχε αξιόπιστες και ταχείες (5 min) μετρήσεις με ευαισθησία ανίχνευσης <0,1% ( ο/ο).Food allergy affects a large percentage of people worldwide. For this reason, international organizations have addressed directives which make mandatory the control and labeling of processed products so as to indicate the presence of allergenic compounds by the food industries. In order to avoid undesirable contamination of food with allergens due to the use of common production lines for different products, it is necessary to control the presence of allergens in both the rinsing water of pipelines and machines, the finished products and the raw materials used as well. The purpose of this PhD dissertation was to develop an optical immunosensor for the simultaneous, real-time, label-free determination of κ-casein, peanut protein, soy protein and gliadin in rinsing water from food industry. The immunosensor was based on an optoelectronic platform fully integrated onto silicon chips and comprised an array of ten Mach-Zehnder (MZI) interferometers along with the corresponding optical sources, enabling the simultaneous detection of multiple analytes in the same sample. To achieve this goal, enzyme-immunoassays (ELISAs) were developed and optimized for all target allergens as well as methods for single and multiple analytes detection with the sensor. The methods developed for the simultaneous determination of allergens were fast (6.5 min) and accurate with detection limits equal to or lower than those provided by the commercially available kits used by food industry. The potential of the sensor to perform in real conditions was evaluated by analyzing rinsing water samples from a dairy indystry and it was found that the results were in good agreement with those obtained by the ELISA methods developed or provided by external international analytical laboratories. In addition, due to its excellent performance for allergen detection in rinsing water, the immunosensor was also evaluated for the detection of goat milk adulteration with cow milk (through bovine k-casein determination). The immunosensor developed found to be reliable and rapid (5 min) with high detection sensitivity (<0.1%, v / v)