Fluorine magnetic resonance imaging (19F MRI) using polymer tracers overcomes limitations of conventional proton MRI by offering enhanced specificity. However, the lack of systematic comparisons among fluorinated polymers has hindered rational tracer design. In this study, we synthesized an extensive library of water-soluble fluorinated copolymers by varying ratios of hydrophilic and fluorinated monomers and evaluated their 19F MRI properties to identify key structure-property relationships. Optimizing the hydrophilicity of the non-fluorinated comonomer increased fluorine content without compromising water solubility, thereby enhancing the MRI signal. Factors such as chemical structure, molecular interactions, and magnetic relaxation times also significantly influenced tracer performance. The optimized copolymer, poly((N-(2,2,2-trifluoroethyl)acrylamide)60-stat-(N-(2-hydroxyethyl)acrylamide)40), exhibited unprecedented 19F MRI sensitivity with detection limits below 1 mg mL-1, the highest reported to date. We demonstrated the tracer's potential through successful in vivo 19F MRI visualization of solid tumors in mouse models, highlighting its promise for advanced biomedical imaging applications.
- Publikační typ
- časopisecké články MeSH
Inspired by the responsiveness of natural systems to their surrounding environments, researchers have sought to understand these biological processes and to develop functional stimuli-responsive polymeric systems for a wide range of applications such as drug delivery, imaging, and regenerative medicine. Both synthetic polymers and biopolymers have been studied and incorporated into assemblies of different morphologies as well as hydrogels with diverse shapes and dimensions. This special issue highlights recent research advances in this area, as well as exciting challenges to be tackled in the upcoming years.
In recent years, polymerization-induced self-assembly (PISA) has emerged as a powerful method for the straightforward synthesis of polymer nanoparticles at high concentration. In this study, we describe for the first time the synthesis of poly(2-oxazoline) nanoparticles by dispersion cationic ring-opening polymerization-induced self-assembly (CROPISA) in n-dodecane. Specifically, a n-dodecane-soluble aliphatic poly(2-(3-ethylheptyl)-2-oxazoline) (PEHOx) block was chain-extended with poly(2-phenyl-2-oxazoline) (PPhOx). While the PhOx monomer is soluble in n-dodecane, its polymerization leads to n-dodecane-insoluble PPhOx, which leads to in situ self-assembly of the formed PEHOx-b-PPhOx copolymers. The polymerization kinetics and micellization upon second block formation were studied, and diverse nanoparticle dispersions were prepared, featuring varying block lengths and polymer concentrations, leading to dispersions with distinctive morphologies and physical properties. Finally, we developed a single-step protocol for the synthesis of polymer nanoparticles directly from monomers via gradient copolymerization CROPISA, which exploits the significantly greater reactivity of EHOx compared to that of PhOx during the statistical copolymerization of both monomers. Notably, this approach provides access to formulations with monomer compositions otherwise unattainable through the block copolymerization method. Given the synthetic versatility and application potential of poly(2-oxazolines), the developed CROPISA method can pave the way for advanced nanomaterials with favorable properties as demonstrated by using the obtained nanoparticles for stabilization of Pickering emulsions.
- Klíčová slova
- CROP, Copolymerization, Nanoparticles, PISA, Poly(2-oxazoline)s,
- Publikační typ
- časopisecké články MeSH
The parasite island syndrome denotes shifts in parasite life histories on islands, which affect parasite diversity, prevalence and specificity. However, current evidence of parasite island syndromes mainly stems from oceanic islands, while sky islands (i.e. mountains isolated by surrounding low-elevation habitats) have received limited attention. To explore the parasite syndrome in Afrotropical sky islands, we examined haemosporidian blood parasites and their bird hosts in two Afromontane regions in Cameroon. Analysing more than 1300 bird blood samples from the Bamenda Highlands and Mount Cameroon, we found considerably reduced parasite lineage diversity and total prevalence in Mt Cameroon, but not in the Bamenda Highlands. We found highly specific parasite-host interactions at both sites and these associations showed significant phylogenetic congruence, suggesting that closely related parasites infect phylogenetically related hosts. These parasite-host associations tend to be shaped mainly by duplications, switches, losses and failures to diverge rather than through co-speciation events. Overall, the high specificity and parasite-host association differences at local scales largely agree with the limited insights from other sky islands. Yet the drivers of these interactions differ geographically, suggesting that unique dynamics of fragmentation and isolation of montane habitats can lead to similar patterns of host-parasite interactions that are shaped by different underlying drivers.
- Klíčová slova
- Cameroon, avian malaria, parasite island syndrome, parasite–host networks, taxon cycles,
- MeSH
- ekosystém MeSH
- fylogeneze * MeSH
- Haemosporida * genetika fyziologie MeSH
- hostitelská specificita * MeSH
- interakce hostitele a parazita * MeSH
- nemoci ptáků parazitologie epidemiologie MeSH
- ostrovy MeSH
- ptáci * parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Kamerun MeSH
- ostrovy MeSH
Amphiphilic gradient copolymers are promising alternatives to block copolymers for self-assembled nanomaterials due to their straightforward synthesis via statistical copolymerization of monomers with different reactivities and hydrophilicity. By carefully selecting monomers, nanoparticles can be synthesized in a single step through gradient copolymerization-induced self-assembly (gPISA). We synthesized highly sensitive 19F MRI nanotracers via aqueous dispersion gPISA of hydrophilic poly(ethylene glycol) methyl ether methacrylate (PEGMA) with core-forming N,N-(2,2,2-trifluoroethyl)acrylamide (TFEAM). The PPEGMA-grad-PTFEAM nanoparticles were optimized to achieve spherical morphology and exceptional 19F MRI performance. Noncytotoxicity was confirmed in Panc-1 cells. In vitro 19F MR relaxometry and imaging demonstrated their diagnostic imaging potential. Notably, these gradient copolymer nanotracers outperformed block copolymer analogs in 19F MRI performance due to their gradient architecture, enhancing 19F relaxivity. The synthetic versatility and superior 19F MRI performance of gradient copolymers highlight their potential in advanced diagnostic imaging applications.
- MeSH
- hydrofobní a hydrofilní interakce MeSH
- kontrastní látky chemie chemická syntéza MeSH
- lidé MeSH
- magnetická rezonanční tomografie metody MeSH
- methakryláty * chemie MeSH
- nádorové buněčné linie MeSH
- nanočástice chemie MeSH
- polyethylenglykoly * chemie MeSH
- polymerizace MeSH
- polymery chemie chemická syntéza MeSH
- zobrazování fluorovou magnetickou rezonancí metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kontrastní látky MeSH
- methakryláty * MeSH
- polyethylene glycol methacrylate MeSH Prohlížeč
- polyethylenglykoly * MeSH
- polymery MeSH
Conventional refinement strategies used for three-dimensional electron diffraction (3D ED) data disregard the bonding effects between the atoms in a molecule by assuming a pure spherical model called the Independent Atom model (IAM) and may lead to an inaccurate or biased structure. Here we show that it is possible to perform a refinement going beyond the IAM with electron diffraction data. We perform kappa refinement which models charge transfers between atoms while assuming a spherical model. We demonstrate the procedure by analysing five inorganic samples; quartz, natrolite, borane, lutecium aluminium garnet, and caesium lead bromide. Implementation of kappa refinement improved the structure model obtained over conventional IAM refinements and provided information on the ionisation of atoms. The results were validated against periodic DFT calculations. The work presents an extension of the conventional refinement of 3D ED data for a more accurate structure model which enables charge density information to be extracted.
- Publikační typ
- časopisecké články MeSH
Magnetic resonance imaging (MRI) relies on appropriate contrast agents, especially for visualizing transplanted cells within host tissue. In recent years, compounds containing fluorine-19 have gained significant attention as MRI probe, particularly in dual 1H/19F-MR imaging. However, various factors affecting probe sensitivity, such as fluorine content and the equivalency of fluorine atoms, must be considered. In this study, we synthesized fluorinated micelles with adjustable surface positive charge density and investigated their physicochemical properties and MRI efficacy in phantoms and labeled cells. While the micelles exhibited clear signals in 19F-MR spectra and imaging, the concentrations required for MRI visualization of labeled cells were relatively high, adversely affecting cell viability. Despite their favourable physicochemical properties, achieving higher labeling rates without compromising cell viability during labeling remains a challenge for potential in vivo applications.
- Klíčová slova
- 19F magnetic resonance imaging, 19F magnetic resonance spectroscopy, Cell labeling, Fluorinated micelles,
- MeSH
- barvení a značení metody MeSH
- fantomy radiodiagnostické MeSH
- fluor chemie MeSH
- halogenace MeSH
- kationty * chemie MeSH
- kontrastní látky chemie MeSH
- lidé MeSH
- magnetická rezonanční tomografie metody MeSH
- micely * MeSH
- myši MeSH
- viabilita buněk * účinky léků MeSH
- zobrazování fluorovou magnetickou rezonancí metody MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- fluor MeSH
- kationty * MeSH
- kontrastní látky MeSH
- micely * MeSH
There has been growing interest in polymeric systems that break down or undergo property changes in response to stimuli. Such polymers can play important roles in biological systems, where they can be used to control the release of therapeutics, modulate imaging signals, actuate movement, or direct the growth of cells. In this Perspective, after discussing the most important stimuli relevant to biological applications, we will present a selection of recent exciting developments. The growing importance of stimuli-responsive polysaccharides will be discussed, followed by a variety of stimuli-responsive polymeric systems for the delivery of small molecule drugs and nucleic acids. Switchable polymers for the emerging area of therapeutic response measurement in theranostics will be described. Then, the diverse functions that can be achieved using hydrogels cross-linked covalently, as well as by various dynamic approaches will be presented. Finally, we will discuss some of the challenges and future perspectives for the field.
- MeSH
- chytré polymery * chemie MeSH
- hydrogely * chemie MeSH
- lidé MeSH
- polymery chemie MeSH
- polysacharidy chemie MeSH
- systémy cílené aplikace léků metody MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- chytré polymery * MeSH
- hydrogely * MeSH
- polymery MeSH
- polysacharidy MeSH
Fluorine magnetic resonance imaging (19F MRI) is a rapidly evolving research area with a high potential to advance the field of clinical diagnostics. In this review, we provide an overview of the recent progress in the field of fluorinated stimuli-responsive polymers applied as 19F MRI tracers. These polymers respond to internal or external stimuli (e.g., temperature, pH, oxidative stress, and specific molecules) by altering their physicochemical properties, such as self-assembly, drug release, and polymer degradation. Incorporating noninvasive 19F labels enables us to track the biodistribution of such polymers. Furthermore, by triggering polymer transformation, we can induce changes in 19F MRI signals, including attenuation, amplification, and chemical shift changes, to monitor alterations in the environment of the tracer. Ultimately, this review highlights the emerging potential of stimuli-responsive fluoropolymer 19F MRI tracers in the current context of polymer diagnostics research.
- MeSH
- chytré polymery chemie MeSH
- fluor chemie MeSH
- koncentrace vodíkových iontů MeSH
- kontrastní látky chemie MeSH
- lidé MeSH
- magnetická rezonanční tomografie metody MeSH
- polymery chemie MeSH
- zobrazování fluorovou magnetickou rezonancí * metody MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- chytré polymery MeSH
- fluor MeSH
- kontrastní látky MeSH
- polymery MeSH
19F magnetic resonance (19F MR) tracers stand out for their wide range of applications in experimental and clinical medicine, as they can be precisely located in living tissues with negligible fluorine background. This contribution demonstrates the long-term dissolution of multiresponsive fluorinated implants designed for prolonged release. Implants were detected for 14 (intramuscular injection) and 20 (subcutaneous injection) months by 19F MR at 4.7 T, showing favorable MR relaxation times, biochemical stability, biological compatibility and slow, long-term dissolution. Thus, polymeric implants may become a platform for long-term local theranostics.
- Publikační typ
- časopisecké články MeSH
