Ανάπτυξη Νέου Φωτοπολυμερικού Υλικού και Μεθόδου Σχηματοποίησης του για την Κατευθυνόμενη Προσκόλληση Κυττάρων σε Επιφάνειες

Τα τελευταία χρόνια παρατηρείται εκτενής χρήση πολυμερών ως υποστρωμάτων για κατευθυνόμενη προσκόλληση και ανάπτυξη κυττάρων, και κυρίως των υλικών που αποτρέπουν την προσκόλληση κυττάρων. Προς την κατεύθυνση αυτή, στόχος της παρούσας εργασίας ήταν η ανάπτυξη ενός νέου φωτολιθογραφικού υλικού που δεν ευνοεί την προσκόλληση των κυττάρων και το οποίο μετά την σχηματοποίηση του θα λειτουργούσε ως υπόστρωμα για την κατευθυνόμενη ανάπτυξη λείων μυϊκών κυττάρων. Από τη βιβλιογραφία είναι γνωστές οι κυτταροαπωθητικές ιδιότητες της πολυαιθυλενογλυκόλης (PEG) και για αυτό το λόγο συντέθηκε ένα κατά συστάδες συμπολυμερές με απαρχητή πρόδρομη ένωση της PEG και πολυ(μεθακρυλικό-2-τετραϋδροπυρανυλεστέρα) (PEG-b-PTHPMA). Αρχικά προσδιορίστηκε η αναλογία των δύο μονομερών που πρόσδιδε στο τελικό υλικό κυτταροαπωθητικές ιδιότητες. Για το σκοπό αυτό, συντέθηκαν και χαρακτηρίστηκαν με φασματοσκοπία υπερύθρου (IR), ορατού-υπεριώδους (UV-Vis), πυρηνικού μαγνητικού συντονισμού (NMR) και με χρωματογραφία αποκλεισμού μεγεθών (SEC), τέσσερα συμπολυμερή. Στη συνέχεια, αφού ελέγχθηκε η σταθερότητα των υμενίων και η επιλεκτική προσκόλληση των κυττάρων σε αυτά, επιλέχθηκε το πολυμερές PEG5000-b-PTHPMA με σύσταση 43% (β/β) PEG και 57% (β/β) PTHPMA για περαιτέρω μελέτη. Αφού βελτιστοποιήθηκε η φωτολιθογραφική διαδικασία για τη σχηματοποίηση του συγκεκριμένου πολυμερούς σε δισκία πυριτίου, κατασκευάστηκαν υποστρώματα με εναλλασσόμενες γραμμικές δομές εύρους 17,5 έως 50 μm και μελετήθηκε η προσκόλληση και η ευθυγράμμιση λείων μυϊκών κυττάρων σε αυτά. Βρέθηκε ότι τα λεία μυϊκά κύτταρα προσκολλώνταν και ευθυγραμμίζονταν σε μεγαλύτερο βαθμό σε επιφάνειες με γραμμικές δομές εύρους 25 και 27,5 μm για τις οποίες μελετήθηκε διεξοδικά η μορφολογία και ο πολλαπλασιασμός των προσκολλημένων κυττάρων. Διαπιστώθηκε μείωση του πολλαπλασιασμού των κυττάρων στις σχηματοποιημένες επιφάνειες σε σχέση με την ελεύθερη επιφάνεια πυριτίου και παράλληλα αύξηση της επιμήκυνσης του κυτταροσκελετού και μείωση της επιφάνειας του πυρήνα, ευρήματα ενδεικτικά της διατήρησης του συσταλτικού φαινοτύπου των κυττάρων. Επομένως, το υλικό και η φωτολιθογραφική διαδικασία που αναπτύχθηκε αναμένεται να βρουν ευρεία εφαρμογή στην κατευθυνόμενη προσκόλληση και ανάπτυξη κυττάρων με απώτερη εφαρμογή στη μηχανική ιστών.The last decades, polymers, and especially copolymers, are frequently used as substrates for the selective adhesion and growth of cells by combining materials that promote cell adhesion with in particular, cell-repellent polymeric materials. Towards this direction, the aim of the present study was the development of a new photolithographic material that does not favor cell adhesion and would, therefore, serve as a substrate for the selective growth of smooth muscle cells. Based on the well-established cell-repellent properties of polyethylene glycol, a copolymer with polyethylene glycol and poly(2-tetrahydropyranyl methacrylate) (PEG-b-PTHPMA) was synthesized. At first the ratio of the two monomers that led to a cell-repellent material was determined. For this purpose, four copolymers were synthesized and characterized by IR, NMR, UV-Vis spectroscopy and size exclusion chromatography (SEC). After testing the stability of the films and the selective adhesion of cells onto them, a polymer PEG5000-b-PTHPMA with composition of 43% (w/w) PEG and 57% (w/w) PTHPMA was selected for further experimentation. The photolithographic patterning of this material was optimized and applied for the creation of substrates with linear patterns of width ranging from 17.5 to 50 μm was evaluated regarding adhesion and alignment of smooth muscle cells. It was found that the optimum line width for smooth muscle cells adhesion and alignment was between 25 and 27,5 μm. Further study of cell morphology and proliferation onto these micropatterned surfaces revealed a decrease in cell proliferation compared to plain silicon substrates. At the same time, an increase in cytoskeleton elongation and a decrease in nucleus surface area were determined; findings that indicate the preservation of cells contractile phenotype. In conclusion, a novel photolithographic material was developed, which could find wide application in guided cell adhesion and growth and finally in tissue engineering

Littoral cell angioma of the spleen accompanied by haemophagocytic syndrome in a dialysis patient suffering from aa amyloidosis

Littoral cell angioma (LCA) is a rare form of vascular tumor unique to the spleen that arises from the specialized endothelial cells that line the splenic sinuses (littoral cells). Haemophagocytic syndrome (HS) is also a rare hematologic disorder that some times accompanies LCA. The authors describe a young dialysis patient with a history of familiar mediteranean fever and secondary amyloidosis who was found to have this rare association of AA amyloidosis with LCA and haemophagocytic syndrome

Optical Immunosensors for Bacteria Detection in Food Matrices

Optical immunosensors are one of the most popular categories of immunosensors with applications in many fields including diagnostics and environmental and food analysis. The latter field is of particular interest not only for scientists but also for regulatory authorities and the public since food is essential for life but can also be the source of many health problems. In this context, the current review aims to provide an overview of the different types of optical immunosensors focusing on their application for the determination of pathogenic bacteria in food samples. The optical immunosensors discussed include sensors based on evanescent wave transduction principles including surface plasmon resonance (SPR), fiber-optic-, interferometric-, grating-coupler-, and ring-resonator-based sensors, as well as reflectometric, photoluminescence, and immunosensors based on surface-enhanced Raman scattering (SERS). Thus, after a short description of each transduction technique, its implementation for the immunochemical determination of bacteria is discussed. Finally, a short commentary about the future trends in optical immunosensors for food safety applications is provided

A 3D-Printed Electrochemical Immunosensor Employing Cd/Se ZnS QDs as Labels for the Rapid and Ultrasensitive Detection of <i>Salmonella typhimurium</i> in Poultry Samples

Salmonella is one of the leading causes of foodborne illnesses worldwide, with poultry products being a major source of contamination. Thus, the detection of salmonella in commercial poultry products is crucial to minimize the effects on public health. Electrochemical sensors are promising tools for bacteria detection due to their sensitivity, simplicity, and potential for on-site analysis. In this work, a three-dimensional (3D) printed electrochemical immunosensor for the determination of Salmonella typhimurium in fresh chicken through a sandwich immunoassay employing biotinylated anti-S. typhimurium antibody followed by streptavidin labeled with Cd/Se ZnS quantum dots (QDs) is presented. The device features three carbon-black polylactic acid electrodes and a holder, and the quantification of S. typhimurium is performed by anodic stripping voltametric (ASV) determination of the Cd(II) released after acidic dissolution of the QDs. To enhance sensitivity, an electroplated bismuth film was deposited on the working electrode, achieving a detection limit of 5 cfu/mL in a total assay time of 25 min, whereas 5 h of sample pre-enrichment was required for the detection of 1 cfu/25 mL of chicken rinse and chicken broth. The method is accurate, with %recovery values ranging from 93.3 to 113% in fresh chicken samples, and repeatable with intra- and inter- assay coefficient of variations S. typhimurium at the point-of-need

Photopatternable materials for guided cell adhesion and growth

Cells in vivo are grown in a highly organized environment defined by the interactions with other cells and the extracellular matrix proteins. Thus, in order to shed light in cellular functions such as adhesion, migration, proliferation, apoptosis and differentiation, the creation of cell culture surfaces that mimic the in vivo environment has emerged. To create such surfaces, many microfabrication techniques have been applied so far. In this review, we focus on application of light-assisted patterning techniques for construction of either 2D or 3D cell culture substrates. In the first section of the review, the principle of the main light-assisted patterning approaches is presented and their advantages and limitations are discussed. In the second section, the influence of micro/ nanopatterned surfaces fabricated with the described methods, on vital cell functions is presented, along with the significance of these findings in the field of tissue engineering and regenerative medicine