Straightforward route to superhydrophilic poly(2-oxazoline)s via acylation of well-defined polyethylenimine

Herein, we describe a new method for the synthesis of superhydrophilic poly(2-alkyl-2-oxazoline)s (PAOx) from poly(2-ethyl-2-oxazoline) (PEtOx). A well-defined linear polyethylenimine was prepared from PEtOx by controlled acidic hydrolysis of its side-chains followed by reacylation with different carboxylic acids. Using this protocol, we obtained a series of new hydrophilic PAOx containing side-chain ether groups with potential in biomaterials science. The relative hydrophilicity of the polymers was assessed, revealing that poly(2-methoxymethyl-2-oxazoline) (PMeO-MeOx) is the most hydrophilic PAOx reported to date. Additionally, the amorphous poly(2-methoxy-ethoxy-ethoxymethyl-2-oxazoline) (PDEGOx) shows the lowest reported glass transition temperature (-25 degrees C) within the PAOx family to date. The biomedical potential of the prepared polymers was further fortified by an in vitro cytotoxicity study, where all polymers appeared to be noncytotoxic. The described synthetic protocol is universal and can be extremely versatile, especially for PAOx that are difficult to prepare by conventional cationic ring-opening polymerization due to the monomer interference and/or degradation

Fluorinated water-soluble poly(2-oxazoline)s as highly sensitive F-19 MRI contrast agents

Recently, F-19 magnetic resonance imaging (MRI) emerged as a powerful noninvasive diagnostic tool in modern medicine. Fluorinated polymer materials represent an attractive class of MRI contrast agents (CAs) due to their structural variability and tunable properties. Herein, we describe for the first time the F-19 MRI of CAs based on fluorinated water-soluble poly(2-oxazoline)s (PAOx), a polymer class with increasing popularity in biomedical sciences. A series of fluorinated PAOx with increasing fluorine content were synthesized by controlled side-chain hydrolysis of poly(2- methyl-2-oxazoline) followed by reacylation of its ethylenimine units by difluoroacetic anhydride. As the increasing fluorine content leads to the copolymer hydrophobization, their composition was optimized for maximal F-19 MRI performance while retaining good solubility in water. The magnetic properties of the water-soluble polymers were studied in vitro by F-19 NMR and MRI, revealing their outstanding relaxation properties and imaging sensitivity. All CAs were found to be noncytotoxic for HeLa cells in vitro. Finally, the diagnostic potential of the new CAs was demonstrated by a successful in vivo F-19 MRI visualization of the selected fluorinated polymer in rats

Embedding of Bacterial Cellulose Nanofibers within PHEMA Hydrogel Matrices: Tunable Stiffness Composites with Potential for Biomedical Applications

Bacterial cellulose (BC) and poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels are both considered as biocompatible materials with potential use in various biomedical applications including cartilage, cardiovascular stent, and soft tissue engineering. In this work, the "ever-wet" process based on in situ UV radical polymerization of HEMA monomer in BC nanofibrous structure impregnated with HEMA was used, and a series of BC-PHEMA composites was prepared. The composite structures were characterized by ATR FT-IR spectroscopy, WAXD, SEM, and TEM techniques. The strategy of using densified BC material of various cellulose fiber contents was applied to improve mechanical properties. The mechanical properties were tested under tensile, dynamic shear, and relaxation modes. The final composites contained 1 to 20 wt% of BC; the effect of the reinforcement degree on morphology, swelling capacity, and mechanical properties was investigated. The biocompatibility test of BC-PHEMA composites was performed using mouse mesenchymal stem cells

Light‐activated carbon monoxide prodrugs based on bipyridyl dicarbonyl ruthenium(II) complexes

Two photoactivatable dicarbonyl ruthenium(II) complexes based on an amide‐functionalised bipyridine scaffold (4‐position) equipped with an alkyne functionality or a green‐fluorescent BODIPY (boron‐dipyrromethene) dye have been prepared and used to investigate their light‐induced decarbonylation. UV/Vis, FTIR and 13C NMR spectroscopies as well as gas chromatography and multivariate curve resolution alternating least‐squares analysis (MCR‐ALS) were used to elucidate the mechanism of the decarbonylation process. Release of the first CO molecule occurs very quickly, while release of the second CO molecule proceeds more slowly. In vitro studies using two cell lines A431 (human squamous carcinoma) and HEK293 (human embryonic kidney cells) have been carried out in order to characterise the anti‐proliferative and anti‐apoptotic activities. The BODIPY‐labelled compound allows for monitoring the cellular uptake, showing fast internalisation kinetics and accumulation at the endoplasmic reticulum and mitochondria

Koloidálně stabilní polypeptidové nanogely: Studie enzymem-zprostředkované nanogelace v inverzní miniemulzi

The current work presents a pivotal study of the nanogelation of the linear poly(N-5-2-hydroxypropyl-L-glutamine) polymer precursor containing tyramine (TYR) units in an inverse miniemulsion by horseradish peroxidase/H2O2-mediated crosslinking. The effects of various n(H2O2)/n(TYR) ratios on the kinetics of nanogelation in the inverse miniemulsion and on the reaction time are investigated by linear sweep voltammetry, while the formation of dityramine crosslinking is explored by fluorescence spectroscopy. The study is completed using dynamic light scattering measurements, nanoparticle tracking analysis, and cryogenic transmission electron microscopy to acquire comprehensive information about the formed nanoparticulate systems. With the optimal ratio n(H2O2)/n(TYR) = 2, the strategy yields in the high-quality 130 nm poly(amino acid)-based nanogel, which is prepared in 2 h. The nanogel is colloidally stable under different temperature and pH conditions for over 168 h. Moreover, the demonstrated nanogel is noncytotoxic for HeLa cells and human primary fibroblasts and is quickly enzymatically hydrolyzed into small fragments during a biodegradation study in human blood plasma. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48725.Tato práce představuje klíčovou studii nanogelace lineárního poly (N-5-2-hydroxypropyl-L-glutamin) polymerního prekurzoru obsahujícího jednotky tyraminu (TYR) v inverzní miniemulzi zesíťováním zprostředkovaným křenovou peroxidázou / H2O2. Účinky různých poměrů n (H2O2) / n (TYR) na kinetiku nanogelace v inverzní miniemulzi a na reakční dobu se zkoumají pomocí lineární rozmítané voltametrie, zatímco tvorba zesítění dityraminu se zkoumá fluorescenční spektroskopií. Studie je dokončena pomocí dynamických měření rozptylu světla, analýzy sledování nanočástic a kryogenní transmisní elektronové mikroskopie za účelem získání komplexních informací o vytvořených nanočásticových systémech. Při optimálním poměru n (H2O2) / n (TYR) = 2 dává strategie vysoce kvalitní nanogel na bázi 130 nm poly (aminokyseliny), který je připraven za 2 hodiny. Nanogel je koloidně stabilní za různých podmínek teploty a pH po více než 168 hodin. Kromě toho je prokázaný nanogel necytotoxický pro HeLa buňky a lidské primární fibroblasty a je rychle enzymaticky hydrolyzován na malé fragmenty během biodegradační studie v lidské krevní plazmě