31 results on '"Verbraeken B"'
Search Results
2. The evaluation of intracranial bypass patency in neurosurgical practice
- Author
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Aboukais, R., primary, Menovsky, T., additional, Verbraeken, B., additional, Gautier, C., additional, Lejeune, J.-P., additional, and Leclerc, X., additional
- Published
- 2021
- Full Text
- View/download PDF
3. Preinduction cervical ripening with prostaglandin E2: influence on psychomotor evolution in the first year
- Author
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Van Pelt, C., primary, De Coster, W., additional, Thiery, M., additional, Parewijck, W., additional, De Baere, C., additional, Verbraeken, B., additional, and Derom, R., additional
- Published
- 1984
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4. Preinduction cervical ripening with prostaglandin E 2: influence on psychomotor evolution in the first year
- Author
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Van Pelt, C., De Coster, W., Thiery, M., Parewijck, W., De Baere, C., Verbraeken, B., and Derom, R.
- Published
- 1984
- Full Text
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5. Correspondence: Microsurgical thrombectomy: Where the ancient art meets the new era.
- Author
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Penders D, Vanloon M, Verbraeken B, Sener S, Baar I, Loos C, Voormolen M, and Menovsky T
- Subjects
- Humans, Endovascular Procedures methods, Ischemic Stroke surgery, Male, Carotid Artery, Internal surgery, Stroke surgery, Treatment Outcome, Thrombectomy methods, Microsurgery methods
- Abstract
Surgical thrombectomy remains a feasible technique in an accurately selected patient population with large vessel occlusion, even though endovascular mechanical thrombectomy is the gold standard. It especially warrants consideration in cases where the endovascular approach is unfeasible or fails. The current extension in the therapeutic window of time in mechanical thrombectomy also provides opportunities to open thrombectomy. To support our view, we present a case of a patient who suffered an ischemic stroke. Intravenous thrombolysis proved ineffective and mechanical thrombectomy was impossible due to extreme tortuosity of the internal carotid artery. Therefore, surgical thrombectomy was performed. The patient underwent successful recovery and states a great satisfaction. To improve efficiency and outcomes, a properly organised and trained surgical team with plentiful neurovascular experience is necessary. Finally, open thrombectomy is the most effective approach to completely restore luminal patency compared to the endovascular approaches yet risks due to the operation should be taken into account., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
- Published
- 2024
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6. Posterior Cerebral Artery-to-Superior Cerebellar Artery Side-to-Side Bypass via Extreme Lateral Supracerebellar Infratentorial Approach: Technical Note.
- Author
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Verbraeken B, Aboukais R, Voormolen M, Van der Zijden T, Boogaarts HD, Vanloon M, and Menovsky T
- Subjects
- Humans, Female, Adult, Neurosurgical Procedures methods, Cerebral Revascularization methods, Intracranial Aneurysm surgery, Intracranial Aneurysm diagnostic imaging, Posterior Cerebral Artery surgery, Posterior Cerebral Artery diagnostic imaging, Cerebellum blood supply, Cerebellum surgery
- Abstract
Background: Difficult-to-treat aneurysms of the distal posterior cerebral artery (PCA) can often be treated by parent artery occlusion. A cerebrovascular bypass can complement PCA occlusion to curb the risk of ischemic complications. An in situ bypass may be considered when the occipital artery or superficial temporal artery cannot serve as a bypass donor. This article describes the use of a side-to-side bypass of superior cerebellar artery as a donor to the PCA via an extreme lateral supracerebellar infratentorial approach (ELSCIT). This bypass approach can be a useful surgical strategy for PCA revascularization., Methods: A 40-year-old woman underwent a side-to-side PCA-superior cerebellar artery bypass via the ELSCIT approach for to treat a complex and previously coiled PCA aneurysm. The bypass was followed by endovascular aneurysm and parent artery occlusion., Results: Postoperatively, the patient experienced transient, partial trochlear nerve palsy of the left eye without ischemic lesions on magnetic resonance imaging. The clinical condition was stable, and angiography showed a patent bypass and complete aneurysm occlusion 12 months after surgery., Conclusions: The ELSCIT approach offers access to the medial and distal PCA that is suitable for a side-to-side PCA-superior cerebellar artery bypass. This type of approach and bypass may be of value when revascularization of a P2-P3 portion of the PCA is needed, but a suitable occipital artery or superficial temporal artery is not available., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)
- Published
- 2024
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7. Letter: Risk of Bone Wax Migration During Retrosigmoid Craniotomy for Microvascular Decompression: Case-Control Study.
- Author
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Vanloon M, Penders D, Verbraeken B, and Menovsky T
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- Humans, Case-Control Studies, Craniotomy adverse effects, Palmitates, Microvascular Decompression Surgery adverse effects, Waxes
- Published
- 2024
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8. Linear Poly(ethylenimine-propylenimine) Random Copolymers for Gene Delivery: From Polymer Synthesis to Efficient Transfection with High Serum Tolerance.
- Author
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Elzes MR, Mertens I, Sedlacek O, Verbraeken B, Doensen ACA, Mees MA, Glassner M, Jana S, Paulusse JMJ, and Hoogenboom R
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- Animals, Aziridines, Gene Transfer Techniques, Mice, Plasmids genetics, Polyethyleneimine chemistry, Transfection, DNA chemistry, Polymers chemistry
- Abstract
Naturally occurring oligoamines, such as spermine, spermidine, and putrescine, are well-known regulators of gene expression. These oligoamines frequently have short alkyl spacers with varying lengths between the amines. Linear polyethylenimine (PEI) is a polyamine that has been widely applied as a gene vector, with various formulations currently in clinical trials. In order to emulate natural oligoamine gene regulators, linear random copolymers containing both PEI and polypropylenimine (PPI) repeat units were designed as novel gene delivery agents. In general, statistical copolymerization of 2-oxazolines and 2-oxazines leads to the formation of gradient copolymers. In this study, however, we describe for the first time the synthesis of near-ideal random 2-oxazoline/2-oxazine copolymers through careful tuning of the monomer structures and reactivity as well as polymerization conditions. These copolymers were then transformed into near-random PEI-PPI copolymers by controlled side-chain hydrolysis. The prepared PEI-PPI copolymers formed stable polyplexes with GFP-encoding plasmid DNA, as validated by dynamic light scattering. Furthermore, the cytotoxicity and transfection efficiency of polyplexes were evaluated in C2C12 mouse myoblasts. While the polymer chain length did not significantly increase the toxicity, a higher PPI content was associated with increased toxicity and also lowered the amount of polymers needed to achieve efficient transfection. The transfection efficiency was significantly influenced by the degree of polymerization of PEI-PPI, whereby longer polymers resulted in more transfected cells. Copolymers with 60% or lower PPI content exhibited a good balance between high plasmid-DNA transfection efficiency and low toxicity. Interestingly, these novel PEI-PPI copolymers revealed exceptional serum tolerance, whereby transfection efficiencies of up to 53% of transfected cells were achieved even under 50% serum conditions. These copolymers, especially PEI-PPI with DP500 and a 1:1 PEI/PPI ratio, were identified as promising transfection agents for plasmid DNA.
- Published
- 2022
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9. Efficacy and histopathological effects of self-assembling peptides RADA16 and IEIK13 in neurosurgical hemostasis.
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Verbraeken B, Lammens M, Van Rompaey V, Ahmed M, Szewczyk K, Hermans C, and Menovsky T
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- Animals, Hemorrhage, Hydrogels pharmacology, Peptides pharmacology, Rats, Hemostasis, Hemostatics pharmacology
- Abstract
There is a continued need for effective hemostatic agents that are safe for neurosurgical use. Self-assembling peptide hydrogels have been suggested as novel hemostatic agents. They offer some advantages for neurosurgical hemostasis (e.g., transparency), but their efficacy and safety for neurosurgery have not been established. In this paper, the efficacy and safety of two self-assembling peptides, RADA16 and IEIK13, are explored for hemostasis of oozing bleeding on the rat cerebral cortex (n = 56). Chronic safety was evaluated by neuropathological evaluation at one, four, and twelve weeks after craniotomy (n = 32). An inactive control and oxidized cellulose served as comparators. Mean time-to-hemostasis was significantly shorter for RADA16 and IEIK13 compared to controls, while safety evaluation yielded similar results. Histopathological response consisted primarily of macrophage infiltration at the lesion site in all groups. This study confirms the hemostatic potential and safety of RADA16 and IEIK13 for hemostasis in the rat brain., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2022
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10. Polyvinyl Alcohol Sponges to Facilitate Cerebral Bypass Surgery: Technical Note.
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Verbraeken B, Lavrysen E, Aboukais R, and Menovsky T
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- Anastomosis, Surgical instrumentation, Anastomosis, Surgical methods, Cerebral Revascularization instrumentation, Humans, Polyvinyl Alcohol chemistry, Cerebral Revascularization methods, Polyvinyl Alcohol administration & dosage, Surgical Sponges
- Abstract
Objective: The standard way of isolating bypass vessels from surrounding structures during cerebral bypass surgery has been to use a rubber dam or neurosurgical patty. Here, the use of polyvinyl alcohol (PVA) sponges is described as a possible upgrade from these traditional bypass dams., Methods: PVA sponges were used to isolate bypass arteries from surrounding tissues during microvascular anastomosis in 25 patients undergoing bypass surgery at our institution., Results: There were no adverse events related to the use of PVA for microvascular anastomosis. PVA sponges offered some specific advantages when compared with rubber and cottonoid dams., Conclusions: Although preliminary, our experience using PVA sponges during microvascular anastomosis suggests some of their properties can facilitate cerebral bypass surgery., (Copyright © 2021 Elsevier Inc. All rights reserved.)
- Published
- 2021
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11. Ruptured blood blister like aneurysm: does the best therapeutic option really exist?
- Author
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Aboukais R, Tétard MC, Devalckeneer A, Boussemart P, Bourgeois P, Bricout N, Verbraeken B, Menovsky T, Leclerc X, and Lejeune JP
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- Humans, Retrospective Studies, Treatment Outcome, Aneurysm, Ruptured surgery, Embolization, Therapeutic, Endovascular Procedures, Intracranial Aneurysm surgery, Subarachnoid Hemorrhage surgery
- Abstract
Our study aimed to evaluate the outcome of patients with ruptured blood-blister like aneurysm (BBLA) in our institution by comparing microsurgical selective treatment to endovascular treatment using flow-diverter stent (FD). Our study included 18 consecutive patients treated for BBLA between 2004 and 2020. Until 2014, microsurgery was preferred in all patients with BBLA (n = 10). Significant postoperative morbi-mortality was recorded at this time and led us to change therapeutic strategy and to favor FD as first-line treatment in all patients (n = 8). Postprocedural complications and BBLA occlusion were recorded. High WFNS score (> 2) was noted in 6 patients of microsurgical group and in 2 of endovascular group. In microsurgical group, ischemic lesions were noted in 6 patients and led to death in 3 patients. Immediate BBLA occlusion was obtained in all patients. Favorable outcome after 3 months (mRS < 3) was recorded in 4 of the 7 survivors. In endovascular group, ischemic lesions were noted in 4 patients. One patient died from early postprocedural BBLA rebleeding. Scarpa hematoma was noted in 3 patients with surgical evacuation in 1. Persistent BBLA at 3 months was recorded in 4 patients without rebleeding, but further FD was required in 1 with growing BBLA. Favorable outcome was noted in 6 of the 7 survivors. Although, rate of morbi-mortality appear lower in patients treated with FD, neurological presentation was better and BBLA diagnosis remains questionable in this group. Moreover, persistent BBLA imaging with potential risk of rebleeding after FD deserves to be discussed., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.)
- Published
- 2021
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12. Extreme Lateral Supracerebellar Infratentorial Approach (ELSCIT) for Occipital Artery-to-Posterior Cerebral Artery Bypass: Results in 3 Cases.
- Author
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Verbraeken B, Aboukais R, Voormolen M, Boogaarts HD, Leclerc X, Lejeune JP, and Menovsky T
- Subjects
- Anastomosis, Surgical, Female, Humans, Male, Middle Aged, Neurosurgical Procedures methods, Young Adult, Cerebral Revascularization methods, Intracranial Aneurysm surgery, Posterior Cerebral Artery surgery
- Abstract
Objective/background: The need for revascularization of the distal posterior cerebral artery (PCA) in the treatment of PCA aneurysms is a contentious issue. Approaches to the PCA, such as the subtemporal route, carry significant perioperative risk. This risk at times outweighs the risk of ischemia associated with endovascular PCA sacrifice. This paper describes the use of an extreme lateral supracerebellar infratentorial (ELSCIT) approach as an alternative technique for distal PCA revascularization., Methods: Between 2016 and 2019, 3 patients underwent a PCA bypass via the ELSCIT approach for the treatment of a PCA aneurysm. In all cases, an end-to-side anastomosis to the P2- or P3-segment of the PCA was made, with the occipital artery as a donor. Bypass procedures were followed by endovascular parent artery occlusion, without ischemic complications., Results: In all 3 cases, the ELSCIT approach offered a broad enough surgical corridor to perform an occipital artery-to-PCA bypass. One patient suffered a cerebrospinal fluid leak that was surgically treated. Patients' clinical conditions were stable on follow-up (mean follow-up of 34 months). All 3 aneurysms remained occluded, and no ischemia was detected on magnetic resonance imaging., Conclusions: The ELSCIT approach offers an alternative route to the distal PCA for extracranial-to-intracranial bypass with seemingly low perioperative morbidity and good surgical access to the PCA., (Copyright © 2021 Elsevier Inc. All rights reserved.)
- Published
- 2021
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13. Induced Moyamoya vessels after extra-intracranial bypass for a giant middle cerebral artery aneurysm exclusion: Case report.
- Author
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Legrand V, Aboukais R, Menovsky T, Bourgeois P, Verbraeken B, Bricout N, Leclerc X, and Lejeune JP
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- Adult, Humans, Male, Middle Cerebral Artery pathology, Middle Cerebral Artery surgery, Cerebral Revascularization adverse effects, Intracranial Aneurysm surgery, Moyamoya Disease etiology
- Published
- 2021
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14. Complete Transection of Optic Nerve After Endovascular Coiling of a Large Ophthalmic Artery Aneurysm.
- Author
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Verbraeken B, Achahbar SE, Kamerling N, Yperzeele L, Voormolen M, Van Havenbergh T, and Menovsky T
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- Adult, Cerebral Angiography, Humans, Imaging, Three-Dimensional, Male, Optic Nerve Injuries diagnosis, Blindness etiology, Embolization, Therapeutic, Endovascular Procedures, Intracranial Aneurysm therapy, Ophthalmic Artery, Optic Nerve Injuries complications
- Abstract
Background: We describe a patient who developed delayed blindness of the left eye at 5 weeks after endovascular coiling of a large ophthalmic aneurysm., Case Description: A 44-year-old male was admitted with visual decline due to compression of the optic nerve by a large ophthalmic aneurysm. The aneurysm was treated by endovascular coiling, but visual function was unchanged. One month and 7 days later, the patient developed sudden blindness of the affected eye, despite complete angiographical occlusion of the aneurysm. Surgical exploration in an attempt to restore vision showed a fully thrombosed aneurysm but, surprisingly, complete transection of the optic nerve just proximal to its entry into the optic canal., Conclusions: This report describes a rare complication of a sudden increase in size of a large ophthalmic aneurysm despite successful endovascular occlusion., (Copyright © 2019 Elsevier Inc. All rights reserved.)
- Published
- 2019
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15. Visualization and design of the functional group distribution during statistical copolymerization.
- Author
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Van Steenberge PHM, Sedlacek O, Hernández-Ortiz JC, Verbraeken B, Reyniers MF, Hoogenboom R, and D'hooge DR
- Abstract
Even though functional copolymers with a low percentage of functional comonomer units (up to 20 mol%) are widely used, for instance for the development of polymer therapeutics and hydrogels, insights in the functional group distribution over the actual chains are lacking and the average composition is conventionally used to describe the functionalization degree. Here we report the visualization of the monomer distribution over the different polymer chains by a synergetic combination of experimental and theoretical analysis aiming at the construction of functionality-chain length distributions (FUNC-CLDs). A successful design of the chemical structure of the comonomer pair, the initial functional comonomer amount (13 mol%), and the temperature (100 °C) is performed to tune the FUNC-CLD of copoly(2-oxazoline)s toward high functionalization degree for both low (100) and high (400) target degrees of polymerization. The proposed research strategy is generic and extendable to a broad range of copolymerization chemistries, including reversible deactivation radical polymerization.
- Published
- 2019
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16. Unexpected Reactivity Switch in the Statistical Copolymerization of 2-Oxazolines and 2-Oxazines Enabling the One-Step Synthesis of Amphiphilic Gradient Copolymers.
- Author
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Sedlacek O, Lava K, Verbraeken B, Kasmi S, De Geest BG, and Hoogenboom R
- Abstract
Poly(2-oxazoline)s and, more recently, also poly(2-oxazine)s represent an emerging class of polymers with a broad range of applications. Surprisingly, to date, the statistical copolymerization of these two cyclic imino ether monomers has not yet been reported. Herein, we demonstrate that the statistical copolymerization of 2-oxazines with 2-oxazolines can lead to the formation of amphiphilic gradient copolymers in a single step. These gradient copolymers combine the high structural modularity of poly(2-oxazoline)s with the excellent biological properties of poly(2-oxazine)s, especially poly(2-methyl-2-oxazine). The copolymerization was found to proceed in a nonexpected way with the relative incorporation rates of the monomers being opposite to the reactivity observed for the corresponding homopolymerizations. In fact, the statistical copolymerizations lead to faster incorporation of the 2-oxazine followed by a gradual transition toward the 2-oxazoline. The self-assembly properties of the prepared amphiphilic poly[(2-methyl-2-oxazine)- grad-(2-butyl-2-oxazoline)] (PMeOzi- grad-PBuOx) as well as the thermoresponsive poly[(2-methyl-2-oxazine)- grad-(2-propyl-2-oxazoline)] (PMeOzi- grad-PPrOx) confirmed their potential as stimuli-responsive nonionic surfactants for various applications. Finally, the noncytotoxic character and cellular uptake of PMeOzi- grad-PBuOx copolymers was confirmed in vitro in SKOV3 cells.
- Published
- 2019
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17. Protective STA-MCA bypass to prevent brain ischemia during high-flow bypass surgery: case series of 10 patients.
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Aboukais R, Verbraeken B, Leclerc X, Gautier C, Vermandel M, Bricout N, Lejeune JP, and Menovsky T
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- Adult, Aged, Anastomosis, Surgical adverse effects, Brain Ischemia diagnostic imaging, Brain Ischemia etiology, Carotid Artery Diseases surgery, Cerebral Revascularization adverse effects, Female, Humans, Magnetic Resonance Imaging, Male, Microsurgery adverse effects, Middle Aged, Postoperative Complications diagnostic imaging, Postoperative Complications etiology, Stroke diagnostic imaging, Stroke etiology, Ultrasonography, Doppler, Anastomosis, Surgical methods, Aneurysm surgery, Brain Ischemia prevention & control, Cerebral Revascularization methods, Microsurgery methods, Postoperative Complications prevention & control, Stroke prevention & control
- Abstract
Background: High-flow extracranial-intracranial bypass is associated with a significant risk of ischemic stroke. The goal of this study is to evaluate the effectiveness of STA-MCA bypass preceding a high-flow bypass as a means of protecting the brain from ischemia during the high-flow bypass anastomosis in patients with otherwise untreatable aneurysms., Materials and Method: This prospective study included 10 consecutive patients treated for complex/giant aneurysm using a previous combined STA-MCA bypass and high-flow EC-IC bypass between June 2016 and January 2018 when classical endovascular or microsurgical exclusion was estimated too risky. Early cranial Doppler, MRI, CT scan, and conventional angiography were performed in each patient to confirm patency of bypasses, measure flow in the anastomoses, detect any ischemic lesions, and evaluate exclusion of the aneurysm., Results: The mean age at treatment was 55 years (range 34 to 67). The mean time of microsurgical procedure was 11 h (range 9 to 12). In all patients, the high-flow bypass was patent intraoperatively and complete occlusion of aneurysm was obtained. No ischemic lesions were noted on early MRI. One patient died from a large hemispheric infarction related to a common carotid artery dissection 10 days after the microsurgical procedure and immediate postoperative epidural hematoma was noted in one other patient., Conclusion: In this study, we described the use of a protective STA-MCA bypass, performed prior to the high-flow bypass, in order to reduce the risk of perioperative ischemic lesions without increasing the morbidity of the surgical procedure. This treatment paradigm was feasible in all ten patients without complications related to the STA-MCA anastomosis.
- Published
- 2019
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18. Straightforward Route to Superhydrophilic Poly(2-oxazoline)s via Acylation of Well-Defined Polyethylenimine.
- Author
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Sedlacek O, Janouskova O, Verbraeken B, and Hoogenboom R
- Subjects
- HeLa Cells, Humans, Hydrophobic and Hydrophilic Interactions, Transition Temperature, Vitrification, Oxazoles chemistry, Polyethyleneimine chemistry
- Abstract
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) (PMeOMeOx) 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 °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.
- Published
- 2019
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19. The Elusive Seven-Membered Cyclic Imino Ether Tetrahydrooxazepine.
- Author
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Verbraeken B, Hullaert J, van Guyse J, Van Hecke K, Winne J, and Hoogenboom R
- Abstract
Cyclic imino ether heterocycles are used as ligands in transition metal catalysis, in various drugs and as reactive monomers in living cationic ring-opening polymerization (CROP). While five- and six-membered cyclic imino ethers, i.e. 2-oxazolines and 4,5-dihydro-1,3-oxazines, have extensively been studied in these areas, their seven-membered ring counterparts have remained unexplored. Herein, we report the synthesis of 2-phenyl-4,5,6,7-tetrahydro-1,3-oxazepine allowing reassignment of the earlier, incorrectly reported 4,5,6,7-tetrahydro-1,3-oxazepines as their N-acylated pyrrolidine isomers. Finally, we also report a comparison of the CROP reactivity of a homologous series of cyclic imino ethers with a 2-carbon, 3-carbon, and 4-carbon methylene bridge, revealing a remarkable ring size effect.
- Published
- 2018
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20. Defined High Molar Mass Poly(2-Oxazoline)s.
- Author
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Monnery BD, Jerca VV, Sedlacek O, Verbraeken B, Cavill R, and Hoogenboom R
- Abstract
Poly(2-alkyl-2-oxazoline)s (PAOx) are regaining interest for biomedical applications. However, their full potential is hampered by the inability to synthesise uniform high-molar mass PAOx. In this work, we proposed alternative intrinsic chain transfer mechanisms based on 2-oxazoline and oxazolinium chain-end tautomerisation and derived improved polymerization conditions to suppress chain transfer, allowing the synthesis of highly defined poly(2-ethyl-2-oxazoline)s up to ca. 50 kDa (dispersity (Ð) <1.05) and defined polymers up to at least 300 kDa (Ð<1.2). The determination of the chain transfer constants for the polymerisations hinted towards the tautomerisation of the oxazolinium chain end as most plausible cause for chain transfer. Finally, the method was applied for the preparation of up to 60 kDa molar mass copolymers of 2-ethyl-2-oxazoline and 2-methoxycarbonylethyl-2-oxazoline., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2018
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21. Letter: Superficial Temporal Artery: Distal Posterior Cerebral Artery Bypass Through the Subtemporal Approach: Technical Note and Pilot Surgical Cases.
- Author
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Verbraeken B, Aboukais R, Lejeune JP, Lukes A, and Menovsky T
- Subjects
- Humans, Posterior Cerebral Artery surgery, Temporal Arteries surgery, Vascular Surgical Procedures, Cerebral Revascularization, Intracranial Aneurysm
- Published
- 2018
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22. Chemical Design of Non-Ionic Polymer Brushes as Biointerfaces: Poly(2-oxazine)s Outperform Both Poly(2-oxazoline)s and PEG.
- Author
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Morgese G, Verbraeken B, Ramakrishna SN, Gombert Y, Cavalli E, Rosenboom JG, Zenobi-Wong M, Spencer ND, Hoogenboom R, and Benetti EM
- Subjects
- Adsorption, Alkylation, Cell Adhesion, Equipment and Supplies, Humans, Lubricants chemistry, Methylation, Surface Properties, Biocompatible Materials chemistry, Oxazines chemistry, Oxazoles chemistry, Polyethylene Glycols chemistry
- Abstract
The era of poly(ethylene glycol) (PEG) brushes as a universal panacea for preventing non-specific protein adsorption and providing lubrication to surfaces is coming to an end. In the functionalization of medical devices and implants, in addition to preventing non-specific protein adsorption and cell adhesion, polymer-brush formulations are often required to generate highly lubricious films. Poly(2-alkyl-2-oxazoline) (PAOXA) brushes meet these requirements, and depending on their side-group composition, they can form films that match, and in some cases surpass, the bioinert and lubricious properties of PEG analogues. Poly(2-methyl-2-oxazine) (PMOZI) provides an additional enhancement of brush hydration and main-chain flexibility, leading to complete bioinertness and a further reduction in friction. These data redefine the combination of structural parameters necessary to design polymer-brush-based biointerfaces, identifying a novel, superior polymer formulation., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2018
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23. Tuning of Thermoresponsivity of a Poly(2-alkyl-2-oxazoline) Block Copolymer by Interaction with Surface-Active and Chaotropic Metallacarborane Anion.
- Author
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Ďorďovič V, Verbraeken B, Hogenboom R, Kereïche S, Matějíček P, and Uchman M
- Abstract
Thermoresponsive nanoparticles based on the interaction of metallacarboranes, bulky chaotropic and surface-active anions, and poly(2-alkyl-2-oxazoline) block copolymers were prepared. Recently, the great potential of metallacarboranes have been recognized in biomedicine and many delivery nanosystems have been proposed. However, none of them are thermoresponsive. Therefore, a thermoresponsive block copolymer, poly(2-methyl-2-oxazoline)-block-poly(2-n-propyl-2-oxazoline) (PMeOx-PPrOx), was synthesized to encapsulate metallacarboranes. Light scattering, NMR spectroscopy, isothermal titration calorimetry, and cryogenic TEM were used to characterize all solutions of the formed nanoparticles. The cloud-point temperature (T
CP ) of the block copolymer was observed at 30 °C and polymeric micelles formed above this temperature. Cobalt bis(dicarbollide) anion (COSAN) interacts with both polymeric segments. Depending on the COSAN concentration, this affinity influenced the phase transition of the thermoresponsive PPrOx block. The TCP shifted to lower values at a lower COSAN content. At higher COSAN concentrations, the hybrid nanoparticles are fragmented into relatively small pieces. This system is also thermoresponsive, whereby an increase in temperature leads to higher polymer mobility and COSAN release., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2018
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24. Fluorinated 2-Alkyl-2-oxazolines of High Reactivity: Spacer-Length-Induced Acceleration for Cationic Ring-Opening Polymerization As a Basis for Triphilic Block Copolymer Synthesis.
- Author
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Kaberov LI, Verbraeken B, Riabtseva A, Brus J, Talmon Y, Stepanek P, Hoogenboom R, and Filippov SK
- Abstract
The synthesis of defined triphilic terpolymers with hydrophilic, lyophilic, and fluorophilic blocks is an important challenge as a basis for the development of multicompartment self-assembled structures with potential for, e.g., cascade catalysis and multidrug loading. The synthesis of fluorophilic poly(2-oxazoline)s generally suffers from a very low reactivity of fluorinated 2-oxazoline monomers in cationic ring-opening polymerization (CROP). We report a systematic study on overcoming the extremely low reactivity of 2-perfluoroalkyl-2-oxazolines in CROP by the insertion of methyl and ethyl hydrocarbon spacers between the 2-oxazoline ring and the trifluoromethyl group. The kinetic studies showed the gradual increase of the rate of polymerization with increasing of the hydrocarbon spacer length. The monomer with an ethyl spacer was found to have similar reactivity as 2-alkyl-2-oxazolines and allowed the synthesis of defined triphilic triblock copolymers.
- Published
- 2018
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25. Poly(2-ethyl-2-oxazoline) conjugates with doxorubicin for cancer therapy: In vitro and in vivo evaluation and direct comparison to poly[N-(2-hydroxypropyl)methacrylamide] analogues.
- Author
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Sedlacek O, Monnery BD, Mattova J, Kucka J, Panek J, Janouskova O, Hocherl A, Verbraeken B, Vergaelen M, Zadinova M, Hoogenboom R, and Hruby M
- Subjects
- Animals, Cell Line, Tumor, Female, Flow Cytometry, HeLa Cells, Humans, MCF-7 Cells, Mice, Mice, Inbred C57BL, Microscopy, Confocal, Acrylamides chemistry, Doxorubicin chemistry, Doxorubicin therapeutic use, Drug Carriers chemistry, Nanomedicine methods, Polyamines chemistry, Polymers chemistry
- Abstract
We designed and synthesized a new delivery system for the anticancer drug doxorubicin based on a biocompatible hydrophilic poly(2-ethyl-2-oxazoline) (PEtOx) carrier with linear architecture and narrow molar mass distribution. The drug is connected to the polymer backbone via an acid-sensitive hydrazone linker, which allows its triggered release in the tumor. The in vitro studies demonstrate successful cellular uptake of conjugates followed by release of the cytostatic cargo. In vivo experiments in EL4 lymphoma bearing mice revealed prolonged blood circulation, increased tumor accumulation and enhanced antitumor efficacy of the PEtOx conjugate having higher molecular weight (40 kDa) compared to the lower molecular weight (20 kDa) polymer. Finally, the in vitro and in vivo anti-cancer properties of the prepared PEtOx conjugates were critically compared with those of the analogous system based on the well-established PHPMA carrier. Despite the relatively slower intracellular uptake of PEtOx conjugates, resulting also in their lower cytotoxicity, there are no substantial differences in in vivo biodistribution and anti-cancer efficacy of both classes of polymer-Dox conjugates. Considering the synthetic advantages of poly(2-alkyl-2-oxazoline)s, the presented study demonstrates their potential as a versatile alternative to well-known PEO- or PHPMA-based materials for construction of drug delivery systems., (Copyright © 2017 Elsevier Ltd. All rights reserved.)
- Published
- 2017
- Full Text
- View/download PDF
26. Block and Gradient Copoly(2-oxazoline) Micelles: Strikingly Different on the Inside.
- Author
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Filippov SK, Verbraeken B, Konarev PV, Svergun DI, Angelov B, Vishnevetskaya NS, Papadakis CM, Rogers S, Radulescu A, Courtin T, Martins JC, Starovoytova L, Hruby M, Stepanek P, Kravchenko VS, Potemkin II, and Hoogenboom R
- Abstract
Herein, we provide a direct proof for differences in the micellar structure of amphiphilic diblock and gradient copolymers, thereby unambiguously demonstrating the influence of monomer distribution along the polymer chains on the micellization behavior. The internal structure of amphiphilic block and gradient co poly(2-oxazolines) based on the hydrophilic poly(2-methyl-2-oxazoline) (PMeOx) and the hydrophobic poly(2-phenyl-2-oxazoline) (PPhOx) was studied in water and water-ethanol mixtures by small-angle X-ray scattering (SAXS), small-angle neutron scattering (SANS), static and dynamic light scattering (SLS/DLS), and
1 H NMR spectroscopy. Contrast matching SANS experiments revealed that block copolymers form micelles with a uniform density profile of the core. In contrast to popular assumption, the outer part of the core of the gradient copolymer micelles has a distinctly higher density than the middle of the core. We attribute the latter finding to back-folding of chains resulting from hydrophilic-hydrophobic interactions, leading to a new type of micelles that we refer to as micelles with a "bitterball-core" structure.- Published
- 2017
- Full Text
- View/download PDF
27. Cyclic Polymers: From Scientific Curiosity to Advanced Materials for Gene Delivery and Surface Modification.
- Author
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Verbraeken B and Hoogenboom R
- Subjects
- Cyclization, Ferrosoferric Oxide chemistry, Metal Nanoparticles chemistry, Surface Properties, Titanium chemistry, Gene Transfer Techniques, Polymers chemistry
- Abstract
Cyclic versus linear: The superiority of cyclic polymers over their linear counterparts is highlighted. Cyclic poly(2-oxazoline)s have been shown to provide excellent shielding properties when grafted to TiO
2 surfaces and Fe3 O4 nanoparticles owing to their ultrahigh grafting densities leading to low friction surfaces, superior antifouling properties, and extreme nanoparticle stabilization., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2017
- Full Text
- View/download PDF
28. Multireactive Poly(2-oxazoline) Nanofibers through Electrospinning with Crosslinking on the Fly.
- Author
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Kalaoglu-Altan OI, Verbraeken B, Lava K, Gevrek TN, Sanyal R, Dargaville T, De Clerck K, Hoogenboom R, and Sanyal A
- Abstract
Crosslinked hydrophilic poly(2-oxazoline)-based nanofibers amenable to facile multifunctionalization are fabricated using alkene-containing poly(2-alkyl-2-oxazoline)s (PAOx) via in situ photoinitiated radical thiol-ene crosslinking during electrospinning. The resulting crosslinked nanofibers are demonstrated to be multifunctionalizable using different chemistries as they contain two functional handles, being the alkene moieties from the parent copolymer and the residual thiol groups from the tetra-thiol-based crosslinker. While the thiol groups in these nanofibers could be passivated or conjugated to install functional molecules through thiol-maleimide conjugation, the alkene groups could sequentially be modified with thiol-containing molecules using photoinitiated radical thiol-ene reactions. Utilization of the photochemically induced conjugation of thiol-bearing molecules to the alkene groups on the nanofibers is used to obtain functionalization in a spatially controlled manner.
- Published
- 2016
- Full Text
- View/download PDF
29. Sulfolane as Common Rate Accelerating Solvent for the Cationic Ring-Opening Polymerization of 2-Oxazolines.
- Author
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Vergaelen M, Verbraeken B, Monnery BD, and Hoogenboom R
- Abstract
The search for alternative solvents for the cationic ring-opening polymerization (CROP) of 2-methyl-2-oxazoline (MeOx) is driven by the poor solubility of P(MeOx) in polymerization solvents such as acetonitrile (CH
3 CN) and chlorobenzene as well as in MeOx itself. In this study, solvent screening has revealed that especially sulfolane is a good solvent for PMeOx. Unexpectedly, an increased propagation rate constant ( kp ) was found for the CROP of MeOx in sulfolane. Further extended kinetic studies at different temperatures (60-180 °C), revealed that the acceleration is due to an increase in frequency factor, while the activation energy ( Ea ) of the reaction is hardly affected. In order to explore the versatility of sulfolane as polymerization solvent for the CROP of 2-oxazolines in general, also the polymerization kinetics of other 2-oxazoline monomers, such as 2-ethyl-2-oxazoline (EtOx) and 2-phenyl-2-oxazoline (PhOx), have been studied, revealing a common acceleration of the CROP of 2-oxazoline monomers in sulfolane. This also enabled more controlled synthesis of PMeOx- block -PPhOx block copolymers that otherwise suffers from solvent incompatibility.- Published
- 2015
- Full Text
- View/download PDF
30. Continuous poly(2-oxazoline) triblock copolymer synthesis in a microfluidic reactor cascade.
- Author
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Baeten E, Verbraeken B, Hoogenboom R, and Junkers T
- Abstract
Cationic ring-opening polymerizations of 2-oxazolines were investigated in continuous microflow reactors. Fast homopolymerizations of 2-ethyl-2-oxazoline (EtOx) and 2-n-propyl-2-oxazoline (nPropOx) were carried out up to 180 °C, yielding well-controlled polymers. Also well-defined diblock and triblock copolymers were produced in a microfluidic reactor cascade, demonstrating the high value of microflow synthesis for the built-up of advanced poly(2-oxazoline)-based polymers.
- Published
- 2015
- Full Text
- View/download PDF
31. Total synthesis of (+/-)-frondosin B and (+/-)-5-epi-liphagal by using a concise (4+3) cycloaddition approach.
- Author
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Laplace DR, Verbraeken B, Van Hecke K, and Winne JM
- Subjects
- Biological Products chemical synthesis, Biological Products chemistry, Crystallography, X-Ray, Cycloaddition Reaction, Cycloheptanes chemistry, Heterocyclic Compounds, 4 or More Rings chemistry, Molecular Conformation, Stereoisomerism, Terpenes chemistry, Heterocyclic Compounds, 4 or More Rings chemical synthesis, Terpenes chemical synthesis
- Abstract
A recently developed (4+3) cycloaddition between dienes and furfuryl alcohols, as precursors of oxyallyl-type cations, has been used as a key step in the racemic syntheses of two natural products: frondosin B and liphagal. This work demonstrates the synthetic potential of this cycloaddition reaction, and offers a short synthetic route to an interesting family of natural products. A full account of these synthetic studies is presented, further illustrating the mechanism, scope, and limitations of this straightforward synthetic method for seven-membered rings., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2014
- Full Text
- View/download PDF
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