Design of a Multifunctional Nanoengineered PLLA Surface by Maximizing the Synergies between Biochemical and Surface Design Bactericidal Effects

This is an open access article published under an ACS AuthorChoice License. See Standard ACS AuthorChoice/Editors' Choice Usage Agreement - https://pubs.acs.org/page/policy/authorchoice_termsofuse.htmlNanotechnology, the manipulation of matter on atomic, molecular, and supramolecular scales, has become the most appealing strategy for biomedical applications and is of great interest as an approach to preventing microbial risks. In this study, we utilize the antimicrobial performance and the drug-loading ability of novel nanoparticles based on silicon oxide and strontium-substituted hydroxyapatite to develop nanocomposite antimicrobial films based on a poly(l-lactic acid) (PLLA) polymer. We also demonstrate that nanoimprint lithography (NIL), a process adaptable to industrial application, is a feasible fabrication technique to modify the surface of PLLA, to alter its physical properties, and to utilize it for antibacterial applications. Various nanocomposite PLLA films with nanosized (black silicon) and three-dimensional (hierarchical) hybrid domains were fabricated by thermal NIL, and their bactericidal activity against Escherichia coli and Staphylococcus aureus was assessed. Our findings demonstrate that besides hydrophobicity the nanoparticle antibiotic delivery and the surface roughness are essential factors that affect the biofilm formation

Development of new polymer nanocomposites containing simultaneously therapeutic agents and bioactive nanoparticles for tissue engineering applications

The main objective of the present PhD thesis was the development of new polymer nanocomposites based on poly(lactic acid),containing simultaneously bioactive nanoparticles and and antibacterial agents, as appropriate biomaterials for tissue engineering applications. To achieve this objective, the lack of bioactivity of poly(lactic acid) PLLA, which is a widely used polymer for pharmaceutical and biomedical applications, should be addressed, by the incorporation of bioinert nanoparticles into the polymer matrix, that even in low concentrations, they induce a biological response. For this purpose, silica nanotubes (SiO2 ntbs), nanocrystalline hydroxyapatite, (nHA), strontium-dopped bioglass nanoparticles, (SrnBG) and strontium-substituted hydroxyapatite nanorods, (SrHA nrds), were synthesized using “bottom up” techniques and wet-chemical methods. The nanoparticles which were synthesized with different chemical composition, morphology and size, were fully characterized and they exhibited remarkable physicochemical, structural and pharmacological properties, while their cytotoxicity was estimated in vitro. The addition of the following nanoparticles: SiO2 ntbs, nHA, SrHA nrds and SrnBG, in the polymer matrix of PLLA at a low concentration of 2.5 wt%, using the spin- coating technique, significantly improved its bioactivity, without changing its chemical composition. Afterwards, mirco-pillars (height 8 μm, diameter 4 μm) were constructed on the surface of nanocomposite films based on PLLA, using Thermal- Nanoimprint Lithography (T-NIL), which is a novel «top down» technique for the fabrication of nanomaterials. From this study, it was found that the roughness of a surface, is directly related to the cell-attachment, since, the micro-topography on the surface of the nanocomposite 3D film PLLA/SrnBG 2.5 w%, acted as an ideal ‘’scaffold’’, for the cell attachment and proliferation of Wharton's jelly-derived mesenchymal stem cells (WJ- MSCs). Afterwards, since microbial growth and biofilm formation is a fundamental challenge underlying various biomaterial-associated applications, the antimicrobial treatment of PLLA was attempted for the first time, exploiting synergistically the benefits of pharmaceutical nanotechnology and T-NIL technique. For this specific purpose, nanoparticles that presented antibacterial activity before and after absorption of chloramphenicol antimicrobial agent (CAM-loaded SrHA nrds και CAM-loaded SiO2 ntbs), were incorporated into PLLA, by spin-coating technique at 1 wt% of the polymer matrix. Interestingly, the antimicrobial treatment which was enhanced by the construction of nature-inspired nano-domains known as «Black Silicon» and «Hierarchical» micro/nano-domains, was found to be highly effective in preventing the attachment of Ε. coli και S. αureus bacteria, on the surface of hybrid-3D PLLA films. Moreover, in order to overcome the issues related to the hydrophobicity and slow degradation rate of PLLA, which limit its in vivo efficacy, D,L-lactide, was co-polymerized with a new monomer (TEHA), which is castor-oil derived di-hydroxy acid. Michael addition and ‘’click’’ chemistry, which were employed for the synthesis of TEHA, proved to be a very promising approach for the synthesis of plant oil derived monomers. Co-polymers with molar ratio TEHA/D,L-lactide 1/140 and with surface micro-topography, constructed by T-NIL technique, turned out to be the most promising and alternative approach to improve the biological response of PLLA.Ο στόχος της παρούσας διδακτορικής διατριβής ήταν η παρασκευή καινοτόμων πολυμερικών βιοϋλικών με βάση το πολυ(γαλακτικό οξύ) (PLLA) και με ταυτόχρονη χρήση νανοπροσθέτων και φαρμακευτικών ουσιών με αντιβακτηριδιακή δράση, τα οποία θα είναι κατάλληλα για ιστομηχανικές εφαρμογές. Για να επιτευχθεί αυτό, θα πρέπει να αντιμετωπιστεί αποτελεσματικά η απουσία βιοενεργότητας του PLLA, που χρησιμοποιείται εκτεταμένα τα τελευταία χρόνια στην φαρμακευτική τεχνολογία αλλά και στην ιστομηχανική. Για τον παραπάνω σκοπό, παρασκευάστηκαν ανόργανα νανοσωματίδια με υψηλή βιοενεργότητα όπως: νανοσωλήνες διοξειδίου του πυριτίου (SiO2 ntbs), νανοκρυσταλλικός υδροξυαπατίτης (nHA), νανοσωματίδια βιοϋάλου με βάση το στρόντιο (SrnBG) και νανοράβδοι στροντίου-υποκατεστημένου υδροξυαπατίτη (SrHA nrds), με αντιδράσεις σύνθεσης “υγρής χημείας”. Τα νανοσωματίδια που παρασκευάστηκαν χαρακτηρίστηκαν πλήρως και αποδείχθηκε, ότι παρουσιάζουν αξιοσημείωτες φυσικοχημικές, μορφολογικές και φαρμακολογικές ιδιότητες.Τα υλικά αυτά χρησιμοποιήθηκαν για την παρασκευή νανοσύνθετων πολυμερών μέσω της τεχνικής της περιστροφικής συν-απόθεσης (spin coating) και σε περιεκτικότητα 2.5 wt%. Από τη μελέτη των νανοσύνθετων υλικών σε κύτταρα βρέθηκε ότι η προσθήκη των νανοσωματίδιων SiO2 ntbs, nHA, SrHA nrds και SrnBG στην πολυμερική μήτρα του PLLA βελτίωσε σημαντικά τη βιοσυμβατότητά του, χωρίς όμως να επηρεάζει τη βασική χημική του σύσταση. Έπειτα, στην επιφάνεια παρασκευασμένων υμενίων αποτυπώθηκαν μικρο-κολώνες (micro-pillars) ύψους 8 μm και διαμέτρου 4 μm χρησιμοποιώντας μια καινοτόμα «top down» τεχνική για την παρασκευή νανοϋλικών, τη λιθογραφία νανο-αποτύπωσης εν θερμώ (thermal-nanoimprint lithography ή T-NIL). Από τα νανοσύνθετα 3D υλικά που μελετήθηκαν, βρέθηκε ότι το PLLA/SrnBG 2.5 w% λειτούργησε σαν το ιδανικότερο “ικρίωμα“ πάνω στο οποίο προσκολληθήκαν και πολλαπλασιάστηκαν μεσεγχυματικά βλατοκύτταρα από τη γέλη του Wharton (WJ-MSCs). Στη συνέχεια, επειδή η επιφανειακή μικροβιακή ανάπτυξη και η δημιουργία βιο-φιλμ είναι ένας κίνδυνος που υποβόσκει σε αρκετές εφαρμογές βιοϋλικών, επιχειρήθηκε για πρώτη φορά, η αντιμικροβιακή τροποποίηση του PLLA, αξιοποιώντας συνεργατικά τα οφέλη της φαρμακευτικής νανοτεχνολογίας και της θερμικής NIL. Για το σκοπό αυτό, τα ανόργανα νανοσωματίδια που παρουσίασαν αντιβακτηριακή δράση χρησιμοποιήθηκαν για την προσρόφηση του αντιμικροβιακού παράγοντα χλωραμφενικόλη (CAM), όπως CAM-loaded SrHA nrds και CAM-loaded SiO2 ntbs και εισήχθησαν στην πολυμερική μήτρα του PLLA με συγκέντρωση 1 wt%, χρησιμοποιώντας την τεχνική του spin coating. Η αντιμικροβιακή τροποποίηση των νανοσύνθετων υμενίων ενισχύθηκε επιπρόσθετα με την επιφανειακή δημιουργία εμπνευσμένων από τη φύση νανο-δομών, τύπου «Black Silicon» και ιεραρχιμένων μικρο/νανο-δομών «Hierarchical» οι οποίες παρασκευάστηκαν με τη θερμική NIL. Ο συνδυασμός των ανόργανων νανοσωματιδίων φορτωμένων με CAM και οι μικτές 3D μικρο/νανο-δομές, παρεμπόδισαν αποτελεσματικότερα την προσκόλληση των βακτηρίων Ε. coli και S. αureus στην επιφάνεια των PLLA νανοσύνθετων υμενίων. Τέλος, προκειμένου να αντιμετωπιστούν ζητήματα που περιορίζουν την αποτελεσματικότητα του PLLA in vivo, όπως η υδροφοβικότητά του και ο αργός ρυθμός υδρόλυσης, το D,L-λακτίδιο συμπολυμερίστηκε με ένα νέο μονομερές, το δι-υδροξυοξύ (ΤΕΗΑ), που παράχθηκε με προσθήκη τύπου Michael της 2-μερκαπτοαιθανόλης στο ενδεκανοϊκό οξύ (καστορέλαιο). Η προσθήκη τύπου Michael ως αντίδραση της “κλικ” χημείας, φάνηκε ότι είναι μια πολλά υποσχόμενη προσέγγιση για τη σύνθεση μονομερών από φυτικά έλαια. Από τη μελέτη της επιφανειακής μικρο-τοπογραφίας σε υμένια αυτών τα οποία παρασκευάστηκαν με την τεχνική της θερμικής NIL, αποδείχθηκε πως τα συμπολυμερή TEHA-co-PDLLA με μοριακή αναλογία 1/140 αποτελούν έναν εναλλακτικό και αποτελεσματικότερο φορέα για τη βελτίωση της βιολογικής απόκρισης του PLLA

An Internet of Things (IoT) Acceptance Model. Assessing Consumer’s Behavior toward IoT Products and Applications

A common managerial and theoretical concern is to know how individuals perceive Internet of Things (IoT) products and applications and how to accelerate adoption of them. The purpose of the current study is to answer, “What are the factors that define behavioral intention to adopt IoT products and applications among individuals?” An IoT adoption model was developed and tested, incorporating pull factors from two different information impact sources: technical and psychological. This study employs statistical structural equation modeling (SEM) in order to examine the conceptual IoT acceptance model. It is demonstrated that facilitated appropriation, perceived usefulness and perceived ease of use, as mediators, significantly influence consumers’ attitude and behavioral intention towards IoT products and applications. User character, cyber resilience, cognitive instrumentals, social influence and trust, all with different significance rates, exhibited an indirect effect, through the three mediators. The IoT acceptance model (IoTAM) upgrades current knowledge on consumers’ behavioral intention and equips practitioners with the knowledge needed to create successful integrated marketing tactics and communication strategies. It provides a solid base for examining multirooted models for the acceptance of newly formed technologies, as it bridges the discontinuity in migrating from information and communication technologies (ICTs) to IoT adoption studies, causing distortions to societies’ abilities to make informed decisions about IoT adoption and use

Chemical conjugation of nucleic acid aptamers and synthetic polymers

International audienceNucleic acid aptamers are chemically-synthesized single-stranded oligonucleotides that fold into specific sequence-dependent configurations. Due to their exceptional recognition properties towards a variety of biological targets, they find applications in many areas of bioscience such as affinity chromatography, drug delivery, biosensors, diagnostics, stem cell research and regenerative medicine. In recent years, aptamers conjugation to synthetic polymers has gained increasing attention, as an effective strategy to control biochemical parameters, uptake mechanisms and pharmacokinetic properties. In this review, we summarize and critically discuss the different approaches that have been used so far for the preparation of aptamer-polymer conjugates. Most of the reported work has been achieved by reacting an aptamer with a functional polymer in solution. Different ligation chemistries such as active ester amidation, thio-Michael addition, direct thiol–disulfide exchange and azide-alkyne Huisgen cycloaddition have been used for that purpose. Alternatively, polymer conjugation can be performed on solid-supports. After chemical synthesis, resin bound aptamers are reacted with a macromolecular reagent or extended by phosphoramidite polymer chemistry. Furthermore, some non-covalent strategies, such as polyelectrolyte complexation, have been reported for the preparation of aptamer-polymer conjugates. The pro and cons of all these strategies are discussed herein

Precisely Defined Aptamer- b -Poly(phosphodiester) Conjugates Prepared by Phosphoramidite Polymer Chemistry

International audienceUniform conjugates combining a DNA aptamer (either anti-MUC1 or ATP aptamer) and a synthetic polymer segment were synthesized by automated phosphoramidite chemistry. This multistep growth polymer chemistry enables the use of both natural (i.e. nucleoside phosphoramidites) and non-natural monomers (e.g. alkyl- and oligo(ethylene glycol)-phosphoramidites). Thus, in the present work, six different aptamer-polymer conjugates were synthesized and characterized by ion-exchange HPLC, circular dichroism spectroscopy and electrospray mass spectrometry. All these methods evidenced the formation of uniform molecules with precisely-controlled chain-length and monomer sequences. Furthermore, aptamer folding was not affected by polymer bioconjugation. The method described herein is straightforward and allows covalent attachment of homopolymers and copolymers to bio-functional DNA aptamers

Magnetic Nanoparticles Create Hot Spots in Polymer Matrix for Controlled Drug Release

International audienceHerein, original magnetic drug delivery nanomaterials for cancer therapy are developed and compared, with the purpose to show active control over drug release by using an alternative magnetic field (AMF). The rationale is to combine polymers and superparamagnetic nanoparticles to trigger such drug release under AMF. Two magnetic nanosystems are thus presented: magnetic nanogels made of thermosensitive and biocompatible polymers and core-shell nanoparticles with a magnetic core and a molecularly imprinted polymer as shell. Both encapsulate doxorubicin (DOX) and the DOX controlled release was investigated in vitro and in cells under AMF excitation. It confirms that the local heat profile at the vicinity of the iron oxide core can be used for the DOX controlled release. It also shows that both nanosystems help delivering more DOX inside the cells compared to internalization of free DOX. Finally, the DOX intracellular release could be remotely triggered under AMF, in athermal conditions, thus enhancing DOX cytotoxicity

Amphiphilic Block Copolymer Microspheres Derived from Castor Oil, Poly(ε-carpolactone), and Poly(ethylene glycol): Preparation, Characterization and Application in Naltrexone Drug Delivery

In the present study, the newly synthesized castor oil-derived thioether-containing ω-hydroxyacid (TEHA) block copolymers with polycaprolactone (TEHA-b-PCL), with methoxypoly(ethylene glycol) (mPEG), (TEHA-b-mPEG) and with poly(ethylene glycol) (PEG) (TEHA-b-PEG-b-TEHA), were investigated as polymeric carriers for fabrication of naltrexone (NLX)-loaded microspheres by the single emulsion solvent evaporation technique. These microspheres are appropriate for the long-term treatment of opioid/alcohol dependence. Physical properties of the obtained microspheres were characterized in terms of size, morphology, drug loading capacity, and drug release. A scanning electron microscopy study revealed that the desired NLX-loaded uniform microspheres with a mean particle size of 5–10 µm were obtained in all cases. The maximum percentage encapsulation efficiency was found to be about 25.9% for the microspheres obtained from the TEHA-b-PEG-b-TEHA copolymer. Differential scanning calorimetry and X-ray diffractometry analysis confirmed the drug entrapment within microspheres in the amorphous state. In vitro dissolution studies revealed that all NLX-loaded formulations had a similar drug release profile: An initial burst release after 24 h, followed by a sustained and slower drug release for up to 50 days. The analysis of the release kinetic data, which were fitted into the Korsmeyer–Peppas release model, indicated that diffusion is the main release mechanism of NLX from TEHA-b-PCL and TEHA-b-mPEG microspheres, while microspheres obtained from TEHA-b-PEG-b-TEHA exhibited a drug release closer to an erosion process

Large Sequence-Defined Supramolecules Obtained by the DNA-Guided Assembly of Biohybrid Poly(phosphodiester)s

International audienceThe DNA-guided assembly of biohybrid sequence-defined poly(phosphodiester)s was investigated. These polymers contain long non-natural segments covalently connected to single-stranded DNA sequences. These biohybrid structures were synthesized by automated phosphoramidite chemistry using both nucleoside and abiological phosphoramidite monomers. Using complementary DNA strands, the precursors were then assembled in aqueous buffer into linear or star-like superstructures. For instance, linear supramolecules containing 442 (352 non-natural monomers connected by three double-stranded DNA bridges of 15 base pairs) and 990 monomers (720 non-natural monomers connected by nine double-stranded DNA bridges of 15 base pairs) were prepared. A four-arm star structure containing 488 monomers (352 non-natural monomers connected by a four-arm junction of 68 base pairs) was also achieved. The formed supramolecules were characterized by electrophoresis, UV spectroscopy, and atomic force microscopy. All these techniques evidenced the formation of the expected supramolecules, although some defects were also evidenced. These results open up interesting avenues for the design of two-dimensional (2D) and three-dimensional (3D) constructs based on informational poly(phosphodiester)