Amphiphilic Poly(2-oxazoline)s with Glycine-Containing Hydrophobic Blocks Tailored for Panobinostat- and Imatinib-Loaded Micelles.

Aiming toward the development of tailored carrier materials for the cytostatics panobinostat and imatinib, an amphiphilic block copolymer composed of poly(2-ethyl-2-oxazoline) and a degradable poly(2-(3-phenylpropyl)-2-oxazoline) analogue (dPPhPrOx-b-PEtOx) was synthesized via a postpolymerization synthesis route based on reacylation of oxidized linear poly(ethylene imine). The obtained dPPhPrOx-b-PEtOx was found to readily self-assemble into well-defined micelles with a critical micelle concentration of 1 µg mL-1. The incubation of HUVEC cells with the blank micelles revealed their excellent cytocompatibility (up to 2 mg mL-1), thus confirming the polymers' suitability for potential drug delivery application. Subsequently, the encapsulation of the two cytostatics, panobinostat and imatinib, into the dPPhPrOx-b-PEtOx micelles was successfully demonstrated (Dh ≈ 80 nm, PDI ≈ 0.16), whereby the well-defined nature of the micelle was maintained upon extended incubation at 37 °C (36 h) and storage at 4 °C (1 month). Labeling of the micelles with Alexa Fluor 594 and Alexa Fluor 647, which form a Förster resonance energy transfer (FRET) pair, indicated the stability of loaded micelles upon dilution until the CMC. Finally, the cytotoxicity of the loaded micelles was investigated against three different cell lines: Medulloblastoma cell lines ONS-76 and DAOY as well as the glioblastoma cell line U87MG. While the panobinostat-loaded micelles displayed similar cytotoxicity compared to the pure drug in the cell lines, imatinib-loaded micelles were found to be more potent compared to the pristine drug, as significantly higher cytotoxicity was observed across all three cell lines.

Organocatalyzed Ring-Opening Polymerization of (S)-3-Benzylmorpholine-2,5-Dione.

A 3-benzylmorpholine-2,5-dione monomer is synthesized from the natural amino acid l-phenylalanine and characterized by means of nuclear magnetic resonance and infrared spectroscopy, electrospray ionization mass spectrometry, and elemental analysis. Subsequent to preliminary polymerization studies, a well-defined poly(ester amide) homopolymer is synthesized via ring-opening polymerization using a binary catalyst system comprising 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and a 1-(3,5-bis(trifluoromethyl)phenyl)-3-cyclohexylthiourea (TU) cocatalyst with a feed ratio of M/I/DBU/TU = 100/1/1/10. Kinetic studies reveal high controllability of the dispersities and molar masses up to conversions of almost 80%. Analysis by mass spectrometry hints toward excellent end-group fidelity at these conditions. In consequence, utilization of hydroxyl-functionalized poly(ethylene glycol) and poly(2-ethyl-2-oxazoline) as macroinitiators results in amphiphilic block copolymers. Bulk miscibility of the building blocks is indicated by differential scanning calorimetry investigations. As more and more promising new drugs are based on hydrophobic molecules featuring aromatic moieties, the novel polyesteramides seem highly promising materials to be used as potential drug delivery vehicles.

Targeting of phagolysosomes containing conidia of the fungus Aspergillus fumigatus with polymeric particles.

Conidia of the airborne human-pathogenic fungus Aspergillus fumigatus are inhaled by humans. In the lung, they are phagocytosed by alveolar macrophages and intracellularly processed. In macrophages, however, conidia can interfere with the maturation of phagolysosomes to avoid their elimination. To investigate whether polymeric particles (PPs) can reach this intracellular pathogen in macrophages, we formulated dye-labeled PPs with a size allowing for their phagocytosis. PPs were efficiently taken up by RAW 264.7 macrophages and were found in phagolysosomes. When macrophages were infected with conidia prior to the addition of PPs, we found that they co-localized in the same phagolysosomes. Mechanistically, the fusion of phagolysosomes containing PPs with phagolysosomes containing conidia was observed. Increasing concentrations of PPs increased fusion events, resulting in 14% of phagolysosomes containing both conidia and PPs. We demonstrate that PPs can reach conidia-containing phagolysosomes, making these particles a promising carrier system for antimicrobial drugs to target intracellular pathogens. KEY POINTS: • Polymer particles of a size larger than 500 nm are internalized by macrophages and localized in phagolysosomes. • These particles can be delivered to Aspergillus fumigatus conidia-containing phagolysosomes of macrophages. • Enhanced phagolysosome fusion by the use of vacuolin1 can increase particle delivery.

Drug delivery of 6-bromoindirubin-3'-glycerol-oxime ether employing poly(D,L-lactide-co-glycolide)-based nanoencapsulation techniques with sustainable solvents.

BACKGROUND: Insufficient solubility and stability of bioactive small molecules as well as poor biocompatibility may cause low bioavailability and are common obstacles in drug development. One example of such problematic molecules is 6-bromoindirubin-3'-glycerol-oxime ether (6BIGOE), a hydrophobic indirubin derivative. 6BIGOE potently modulates the release of inflammatory cytokines and lipid mediators from isolated human monocytes through inhibition of glycogen synthase kinase-3 in a favorable fashion. However, 6BIGOE suffers from poor solubility and short half-lives in biological aqueous environment and exerts cytotoxic effects in various mammalian cells. In order to overcome the poor water solubility, instability and cytotoxicity of 6BIGOE, we applied encapsulation into poly(D,L-lactide-co-glycolide) (PLGA)-based nanoparticles by employing formulation methods using the sustainable solvents Cyrene™ or 400 g/mol poly(ethylene glycol) as suitable technology for efficient drug delivery of 6BIGOE. RESULTS: For all preparation techniques the physicochemical characterization of 6BIGOE-loaded nanoparticles revealed comparable crystallinity, sizes of about 230 nm with low polydispersity, negative zeta potentials around - 15 to - 25 mV, and biphasic release profiles over up to 24 h. Nanoparticles with improved cellular uptake and the ability to mask cytotoxic effects of 6BIGOE were obtained as shown in human monocytes over 48 h as well as in a shell-less hen's egg model. Intriguingly, encapsulation into these nanoparticles fully retains the anti-inflammatory properties of 6BIGOE, that is, favorable modulation of the release of inflammation-relevant cytokines and lipid mediators from human monocytes. CONCLUSIONS: Our formulation method of PLGA-based nanoparticles by applying sustainable, non-toxic solvents is a feasible nanotechnology that circumvents the poor bioavailability and biocompatibility of the cargo 6BIGOE. This technology yields favorable drug delivery systems for efficient interference with inflammatory processes, with improved pharmacotherapeutic potential.

Rare germline variants in the E-cadherin gene CDH1 are associated with the risk of brain tumors of neuroepithelial and epithelial origin.

The genetic basis of brain tumor development is poorly understood. Here, leukocyte DNA of 21 patients from 15 families with ≥ 2 glioma cases each was analyzed by whole-genome or targeted sequencing. As a result, we identified two families with rare germline variants, p.(A592T) or p.(A817V), in the E-cadherin gene CDH1 that co-segregate with the tumor phenotype, consisting primarily of oligodendrogliomas, WHO grade II/III, IDH-mutant, 1p/19q-codeleted (ODs). Rare CDH1 variants, previously shown to predispose to gastric and breast cancer, were significantly overrepresented in these glioma families (13.3%) versus controls (1.7%). In 68 individuals from 28 gastric cancer families with pathogenic CDH1 germline variants, brain tumors, including a pituitary adenoma, were observed in three cases (4.4%), a significantly higher prevalence than in the general population (0.2%). Furthermore, rare CDH1 variants were identified in tumor DNA of 6/99 (6%) ODs. CDH1 expression was detected in undifferentiated and differentiating oligodendroglial cells isolated from rat brain. Functional studies using CRISPR/Cas9-mediated knock-in or stably transfected cell models demonstrated that the identified CDH1 germline variants affect cell membrane expression, cell migration and aggregation. E-cadherin ectodomain containing variant p.(A592T) had an increased intramolecular flexibility in a molecular dynamics simulation model. E-cadherin harboring intracellular variant p.(A817V) showed reduced ß-catenin binding resulting in increased cytosolic and nuclear ß-catenin levels reverted by treatment with the MAPK interacting serine/threonine kinase 1 inhibitor CGP 57380. Our data provide evidence for a role of deactivating CDH1 variants in the risk and tumorigenesis of neuroepithelial and epithelial brain tumors, particularly ODs, possibly via WNT/ß-catenin signaling.

Poly(2-ethyl-2-oxazoline) Featuring a Central Amino Moiety.

The incorporation of an amino group into a bifunctional initiator for the cationic ring-opening polymerization (CROP) is achieved in a two-step reaction. Detailed kinetic studies using 2-ethyl-2-oxazoline demonstrate the initiators' eligibility for the CROP yielding well-defined polymers featuring molar masses of about 2000 g mol-1 . Deprotection of the phthalimide moiety subsequent to polymerization enables the introduction of a cyclooctyne group in central position of the polymer which is further exploited in a strain-promoted alkyne-azide click reaction (SpAAC) with a Fmoc-protected azido lysine representing a commonly used binding motif for site specific polymer-protein/peptide conjugation. In-depth characterization via electrospray ionization mass spectrometry (ESI) confirms the success of all post polymerization modification steps.

The effects of sediment traps on instream habitat and macroinvertebrates of mountain streams.

Sediment transport in mountain streams can be a major hazard to downstream infrastructure. Consequently, sediment traps are a common feature in many high gradient streams to retain large volumes of sediment and protect settlements from major sediment transport events. Despite the wide application of these instream structures, there is little knowledge regarding the environmental and ecological effects on streams. Here, we investigated the hydromorphological effects of sediment traps on instream habitats and associated macroinvertebrate communities in four impacted and three non-impacted streams in Switzerland. Sediment traps significantly disrupted the sediment regime homogenising grain size percentiles compared to the natural stepwise downstream fining in control streams. This disruption in the sediment regime resulted in finer grain size distributions upstream of the sediment trap, and reduced substrate diversity in the sediment retention basin and just downstream of the trap. The reductions in substrate diversity resulted in an altered macroinvertebrate community composition. Further, the disconnection in sediment transport led to a lack of longitudinal correlation in macroinvertebrate communities. Refugia provision downstream of the sediment trap, and resource availability within the retention basin, were diminished, potentially reducing resilience of macroinvertebrate assemblages to instream disturbances. The effects of sediment traps were most likely localised in three of the four streams with substrate diversity recovering to comparable control values within 8 wetted widths (ca. 50 m) downstream of the trap associated with natural longitudinal fining. In contrast, ecological and environmental effects propagated downstream in one impacted stream with no recovery being evident. Sediment retention basins in the impacted streams provided a local artificially unique habitat of dynamic-braided channels. Our results indicate that sediment traps can significantly disrupt the sediment regime with important consequences for instream ecology and environmental conditions, although these effects can be system specific. Further work is needed to fully understand the effects of sediment traps in mountain streams to assist resource managers in the mitigation and future construction of these structures.

An fMRI Study of Affective Congruence across Visual and Auditory Modalities.

Evaluating multisensory emotional content is a part of normal day-to-day interactions. We used fMRI to examine brain areas sensitive to congruence of audiovisual valence and their overlap with areas sensitive to valence. Twenty-one participants watched audiovisual clips with either congruent or incongruent valence across visual and auditory modalities. We showed that affective congruence versus incongruence across visual and auditory modalities is identifiable on a trial-by-trial basis across participants. Representations of affective congruence were widely distributed with some overlap with the areas sensitive to valence. Regions of overlap included bilateral superior temporal cortex and right pregenual anterior cingulate. The overlap between the regions identified here and in the emotion congruence literature lends support to the idea that valence may be a key determinant of affective congruence processing across a variety of discrete emotions.

Caspofungin Functionalized Polymethacrylates with Antifungal Properties.

We describe the synthesis of hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate) (PmPEGMA) and hydrophobic poly(methyl methacrylate) (PMMA) caspofungin conjugates by a post-polymerization modification of copolymers containing 10 mol % pentafluorophenyl methacrylate (PFPMA), which were obtained via reversible addition-fragmentation chain transfer copolymerization. The coupling of the clinically used antifungal caspofungin was confirmed and quantified in detail by a combination of 1H-, 19F- and diffusion-ordered NMR spectroscopy, UV-vis spectroscopy, and size exclusion chromatography. The trifunctional amine-containing antifungal was attached via several amide bonds to the hydrophobic PMMA, but sterical hindrance induced by the mPEGMA side chains prohibited intramolecular double functionalization. Both polymer-drug conjugates revealed activity against important human-pathogenic fungi, that is, two strains of Aspergillus fumigatus and one strain of Candida albicans (2.5 mg L-1 < MEC < 8 mg L-1, MIC50 = 4 mg L-1), whereas RAW 264.7 macrophages as well as HeLa cells remained unaffected at these concentrations.

Polyester Stereocomplexes Beyond PLA: Could Synthetic Opportunities Revolutionize Established Material Blending?

This review summarizes the current literature regarding stereocomplexation of different polyesters based on α- as well as ß-hydroxy acids beyond the well-known poly(lactic acid). Representing the initial step toward stereocomplexation, synthetic approaches needed to obtain and analyze isotactic polyesters are summarized. The basic technologies for the preparation and characterization of the respective stereocomplexes (SCs) are described, and published material properties are related to the structure of the respective polyesters. The variety of available SC materials is very limited despite the multiple options provided by state-of-the-art stereoselective monomer synthesis and polymerization methods. A combination of knowledge from the three scientific areas (i.e., organic chemistry, synthetic macromolecular chemistry, and materials science) thus has enormous potential to create novel materials with additional features enabled by the introduction of functional moieties to such materials besides the adjustment of thermal as well as mechanical properties.

Strontium Isopropoxide: A Highly Active Catalyst for the Ring-Opening Polymerization of Lactide and Various Lactones.

Commercially available strontium isopropoxide represents a suitable catalyst/initiator for the ring-opening polymerization (ROP) of lactide (LA), ε-caprolactone, δ-valerolactone, δ-caprolactone, and δ-decalactone. Well-defined polyesters are accessible via the solution polymerization of lactide in toluene with a [LA]:[Sr] ratio of 100:1 at room temperature with or without the addition of dodecanol as coinitiator. Kinetic studies and detailed analysis by means of matrix-assisted laser desorption ionization mass spectrometry reveal pseudo-first-order kinetics of the ROP as well as excellent endgroup fidelity of the polylactide (PLA) with isopropyl and dodecyl α-endgroups. Both isopropanolate moieties as well as the coinitiator each initiate PLA chains, enabling the synthesis of PLA with tailored molar mass. The polymerization of ε-caprolactone and δ-valerolactone confirms the high catalyst activity, which causes quantitative monomer conversion after 1 min polymerization time but broad molar mass distributions. In contrast, the catalyst is well suited for the ROP of the less reactive δ-caprolactone and δ-decalactone. Although kinetic studies reveal initially bimodal molar mass distributions, polyesters with dispersity values Ð < 1.2 and unimodal molar mass distributions can be obtained at moderate to high monomer conversions.

The Power of Shielding: Low Toxicity and High Transfection Performance of Cationic Graft Copolymers Containing Poly(2-oxazoline) Side Chains.

We show the potential of oligo(2-ethyl-2-oxazoline) (Oxn)-shielded graft copolymers of (2-aminoethyl)-methacrylate and N-methyl-(2-aminoethyl)-methacrylate for pDNA delivery in HEK cells. For the effect of grafting density and side chain length concerning improved transfection properties through the concept of shielding to be investigated, copolymers were synthesized via the macromonomer method using a combination of cationic ring opening polymerization and reversible addition-fragmentation chain transfer polymerization to vary the degree of grafting (DG = 10 and 30%) as well as the side chain degree of polymerization (DP = 5 and 20). Investigations of the polyplex formation, in vitro flow cytometry, and confocal laser scanning microscopy measurements on the copolymer library revealed classical shielding properties of the Ox side chains, including highly reduced cytotoxicity and a partial decrease in transfection efficiency, as also reported for polyethylene glycol shielding. In terms of the transfection efficiency, the best performing copolymers (A- g-Ox5(10) and M- g-Ox5(10)) revealed equal or better performances compared to those of the corresponding homopolymers. In particular, the graft copolymers with low DG and side chain DP transfected well with over 10-fold higher IC50 values. In contrast, a DG of 30% resulted in a loss of transfection efficiency due to missing ability for endosomal release, and a side chain DP of 20 hampered the cellular uptake.

TBD-Catalyzed Ring-Opening Polymerization of Alkyl-Substituted Morpholine-2,5-Dione Derivatives.

In a two-step synthesis, five different alkyl-substituted morpholine-2,5-dione monomers were synthesized from the natural amino acids glycine, alanine, valine, leucine, and isoleucine. The heterocyclic compounds crystallize in a boat-like conformation and are polymerized via 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)-catalyzed ring-opening polymerization (ROP) in tetrahydrofuran. Well-defined polymers could be obtained from the monomers based on valine, leucine, and isoleucine at a feed ratio of M/I/TBD = 100/1/0.5. Kinetic studies of the ROP reveal that the molar masses and dispersities (D < 1.2) could be well controlled, as confirmed by size exclusion chromatography and 1 H NMR spectroscopy. At conversions above 50%, the polymerization rate decreases and the dispersity slightly increases, presumably due to transesterification. Matrix-assisted laser desorption time-of-flight mass spectrometry indicates the presence of polymer chains with α-end groups derived from the initiator.

Modelling audiovisual integration of affect from videos and music.

Two experiments examined how affective values from visual and auditory modalities are integrated. Experiment 1 paired music and videos drawn from three levels of valence while holding arousal constant. Experiment 2 included a parallel combination of three levels of arousal while holding valence constant. In each experiment, participants rated their affective states after unimodal and multimodal presentations. Experiment 1 revealed a congruency effect in which stimulus combinations of the same extreme valence resulted in more extreme state ratings than component stimuli presented in isolation. An interaction between music and video valence reflected the greater influence of negative affect. Video valence was found to have a significantly greater effect on combined ratings than music valence. The pattern of data was explained by a five parameter differential weight averaging model that attributed greater weight to the visual modality and increased weight with decreasing values of valence. Experiment 2 revealed a congruency effect only for high arousal combinations and no interaction effects. This pattern was explained by a three parameter constant weight averaging model with greater weight for the auditory modality and a very low arousal value for the initial state. These results demonstrate key differences in audiovisual integration between valence and arousal.

What Are Predictors for Persistence in Childhood Stuttering?

Over the past 10 years, we (the Purdue Stuttering Project) have implemented longitudinal studies to examine factors related to persistence and recovery in early childhood stuttering. Stuttering develops essentially as an impairment in speech sensorimotor processes that is strongly influenced by dynamic interactions among motor, language, and emotional domains. Our work has assessed physiological, behavioral, and clinical features of stuttering within the motor, linguistic, and emotional domains. We describe the results of studies in which measures collected when the child was 4 to 5 years old are related to eventual stuttering status. We provide supplemental evidence of the role of known predictive factors (e.g., sex and family history of persistent stuttering). In addition, we present new evidence that early delays in basic speech motor processes (especially in boys), poor performance on a nonword repetition test, stuttering severity at the age of 4 to 5 years, and delayed or atypical functioning in central nervous system language processing networks are predictive of persistent stuttering.

Bifunctional Initiators as Tools to Track Chain Transfer during the CROP of 2-Oxazolines.

Detailed kinetic studies during the cationic ring-opening polymerization (CROP) of 2-ethyl-2-oxazoline (EtOx) are conducted using four bifunctional bromo-type initiators in N,N-dimethylformamide (DMF) at 140 °C. Serving as models to quantify chain transfer to monomer occurring during the CROP initiated by monofunctional initiators, size exclusion chromatography (SEC) resolves a second molar mass distribution with lower molar mass at initial [monomer] to [initiation site] ratios ([M]0 /[I]0 ) of 25, while the resolution is insufficient at [M]0 /[I]0 of 10. Slightly slow initiation is revealed at [M]0 /[I]0 = 25, which prohibits the derivation of chain transfer rates by fitting of the size exclusion chromatography (SEC) data. Although conventional kinetic plots give no indication of significant amounts of chain transfer, the molar mass distributions resolved by SEC can unambiguously be identified as such by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) in both the high as well as the low m/z regions of the mass spectra.

Childhood Stuttering: Where Are We and Where Are We Going?

Remarkable progress has been made over the past two decades in expanding our understanding of the behavioral, peripheral physiologic, and central neurophysiologic bases of stuttering in early childhood. It is clear that stuttering is a neurodevelopmental disorder characterized by atypical development of speech motor planning and execution networks. The speech motor system must interact in complex ways with neural systems mediating language and other cognitive and emotional processes. During the time when stuttering typically appears and follows its path to either recovery or persistence, all of these neurobehavioral systems are undergoing rapid and dramatic developmental changes. We summarize our current understanding of the various developmental trajectories relevant for the understanding of stuttering in early childhood. We also present theoretical and experimental approaches that we believe will be optimal for even more rapid progress toward developing better and more targeted treatment for stuttering in the preschool children who are more likely to persist in stuttering.

Cryogels Based on Poly(2-oxazoline)s through Development of Bi- and Trifunctional Cross-Linkers Incorporating End Groups with Adjustable Stability.

1,4-Bis(iodomethyl)benzene and 1,3,5-tris(iodomethyl)benzene were used as initiators for the cationic ring-opening polymerization (CROP) of 2-ethyl-2-oxazoline (EtOx) and its copolymerization with tert-butyl (3-(4,5-dihydrooxazol-2-yl)propyl)carbamate (BocOx) or methyl 3-(4,5-dihydrooxazol-2-yl)propanoate (MestOx). Kinetic studies confirmed the applicability of these initiators. Termination with suitable nucleophiles resulted in two- and three-armed cross-linkers featuring acrylate, methacrylate, piperazine-acrylamide, and piperazine-methacrylamide as polymerizable ω-end groups. Matrix-assisted laser desorption/ionization mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy confirmed the successful attachment of the respective ω-end groups at all initiation sites for every prepared cross-linkers. Except for acrylate, each ω-end group remained stable during deprotection of BocOx containing cross-linkers. The cryogels were prepared using EtOx-based cross-linkers, as confirmed by solid-state NMR spectroscopy, scanning electron microscopy, and thermogravimetric analysis. Stability tests revealed a complete dissolution of the acrylate-containing gels at pH = 14, whereas the piperazine-acrylamide-based cryogels featured excellent hydrolytic stability.

The Effect of Stereocomplexation and Crystallinity on the Degradation of Polylactide Nanoparticles.

Polymeric nanoparticles (PNPs) are frequently researched and used in drug delivery. The degradation of PNPs is highly dependent on various properties, such as polymer chemical structure, size, crystallinity, and melting temperature. Hence, a precise understanding of PNP degradation behavior is essential for optimizing the system. This study focused on enzymatic hydrolysis as a degradation mechanism by investigation of the degradation of PNP with various crystallinities. The aliphatic polyester polylactide ([C3H4O2]n, PLA) was used as two chiral forms, poly l-lactide (PlLA) and poly d-lactide (PdLA), and formed a unique crystalline stereocomplex (SC). PNPs were prepared via a nanoprecipitation method. In order to further control the crystallinity and melting temperatures of the SC, the polymer poly(3-ethylglycolide) [C6H8O4]n (PEtGly) was synthesized. Our investigation shows that the PNP degradation can be controlled by various chemical structures, crystallinity and stereocomplexation. The influence of proteinase K on PNP degradation was also discussed in this research. AFM did not reveal any changes within the first 24 h but indicated accelerated degradation after 7 days when higher EtGly content was present, implying that lower crystallinity renders the particles more susceptible to hydrolysis. QCM-D exhibited reduced enzyme adsorption and a slower degradation rate in SC-PNPs with lower EtGly contents and higher crystallinities. A more in-depth analysis of the degradation process unveiled that QCM-D detected rapid degradation from the outset, whereas AFM exhibited delayed changes of degradation. The knowledge gained in this work is useful for the design and creation of advanced PNPs with enhanced structures and properties.

Detailed characterization of poly(2-ethyl-2oxazoline)s by energy variable collision-induced dissociation study.

RATIONALE: Poly(2-oxazoline)s are important polymers and can be considered as pseudo-peptides which makes them important for biomedical and life science applications. This prompts the need for a detailed characterization of these polymers via different analytical tools such as mass spectrometry. Here, the energy-variable collision-induced dissociation (CID) of poly(2-ethyl-2-oxazoline)s was studied by electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOFMS/MS) to gain further structural information about this polymer type. METHODS: All polymers were analyzed using manual flow injection of samples into an ESI-QTOF mass spectrometer. Mass spectra (MS and MS/MS) were obtained in the positive ion mode over a mass-to-charge (m/z) range from 50 to 3000. RESULTS: The dependency of the fragmentation patterns as a function of collision energy was examined and the characteristic collision energy (CCE or CE50 ) values for various poly(2-ethyl-2-oxazoline)s with different end-groups were calculated. The effect of molar masses on the CCE values was investigated via the survival yield (SY) method and a linear relationship between CCE values and the degree of polymerization for the PEtOx polymers was observed. CONCLUSIONS: This study showed that ESI-MS/MS is very useful for differentiating poly(2-ethyl-2-oxazoline)s with different end-groups by varying the collision energy. The SY method has the potential to determine the importance of the end-groups on the fragmentation behavior of this polymer type.