Poloxamer Thermogel Systems as Medium for Crystallization

Cespi, Marco; Bonacucina, Giulia; Casettari, Luca; Mencarelli, Giovanna; Palmieri, G

doi:10.1007/s11095-011-0606-3

Cited by 18 publications

(14 citation statements)

References 20 publications

(20 reference statements)

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“…In particular, the F-127 compound has been used for e.g. crystallization (Cespi et al, 2012), treatment of burns (Schmolka, 1972) and pharmaceutical formulations (Escobar-Chá vez et al, 2006). This last field, together with the food industry, also heavily employs a cellulose derivative, carboxymethyl cellulose sodium salt (NaCMC) as a thickening and gelling agent (Hollabaugh et al, 1945;Saha & Bhattacharya, 2010).…”

Section: Resultsmentioning

confidence: 99%

Viscous hydrophilic injection matrices for serial crystallography

Kovacsova

Grünbein

Kloos

et al. 2017

Int Union Crystallogr J

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Serial (femtosecond) crystallography at synchrotron and X-ray free-electron laser (XFEL) sources distributes the absorbed radiation dose over all crystals used for data collection and therefore allows measurement of radiation damage prone systems, including the use of microcrystals for room-temperature measurements. Serial crystallography relies on fast and efficient exchange of crystals upon X-ray exposure, which can be achieved using a variety of methods, including various injection techniques. The latter vary significantly in their flow rates -gas dynamic virtual nozzle based injectors provide very thin fast-flowing jets, whereas high-viscosity extrusion injectors produce much thicker streams with flow rates two to three orders of magnitude lower. High-viscosity extrusion results in much lower sample consumption, as its sample delivery speed is commensurate both with typical XFEL repetition rates and with data acquisition rates at synchrotron sources. An obvious viscous injection medium is lipidic cubic phase (LCP) as it is used for in meso membrane protein crystallization. However, LCP has limited compatibility with many crystallization conditions. While a few other viscous media have been described in the literature, there is an ongoing need to identify additional injection media for crystal embedding. Critical attributes are reliable injection properties and a broad chemical compatibility to accommodate samples as heterogeneous and sensitive as protein crystals. Here, the use of two novel hydrogels as viscous injection matrices is described, namely sodium carboxymethyl cellulose and the thermo-reversible block polymer Pluronic F-127. Both are compatible with various crystallization conditions and yield acceptable X-ray background. The stability and velocity of the extruded stream were also analysed and the dependence of the stream velocity on the flow rate was measured. In contrast with previously characterized injection media, both new matrices afford very stable adjustable streams suitable for time-resolved measurements.

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Section: Resultsmentioning

confidence: 99%

Viscous hydrophilic injection matrices for serial crystallography

Kovacsova

Grünbein

Kloos

et al. 2017

Int Union Crystallogr J

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“…All the free films were characterized by similar thickness and water content as reported in Table . The moisture percentages in the films were comparable with values reported in the literature for pure HPMC films . However, after visual inspection, remarkable differences were observed comparing all the prepared films (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…All the free films prepared were analyzed using DSC. This technique resulted to the ability to detect the copolymer melting, whereas it showed low resolution concerning the HPMC Tg at around 150–170°C (Figure SF3 in supplementary materials). The presence of the copolymers melting peaks on DSC traces suggests that these materials are not completely dispersed in the films, thus the analysis of melting transitions of copolymers allows to study the effect of HPMC matrix on the crystallinity of mPEG‐PLA.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of methoxy polyethylene glycol‐polylactide diblock copolymers as additive in hypromellose film coating

Cespi

Casettari

Bonacucina

et al. 2013

Polymers for Advanced Techs

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This paper deals with a new application of diblock methoxy polyethylene glycol-polylactide block copolymers, a class of synthetic biomaterials largely studied in the pharmaceutical and biomedical fields owing to their favorable properties such as biocompatibility, biodegradability, low immunogenicity, and good mechanical properties. In this work, these materials were evaluated as additives for gastro-soluble pharmaceutical coating aimed to reduce film stiffness and water permeability. Two copolymers with different polylactide chain lengths were synthesized and characterized in term of molecular weight and solid-state properties. A series of free films with different hypromellose/copolymers ratio were prepared and characterized in terms of appearance, components miscibility, plasticity, and water vapor permeability. The obtained results demonstrate that copolymers effectively influence hypromellose film properties according to their concentration and molecular weight. Specifically, the addition of the copolymer with a molecular weight of 6.5kDa in a ratio hypromellose:polymer 5:1, allowed to obtain films with good appearance, improved plasticization, and water permeability properties. For higher molecular weight, copolymer or different ratios was not possible to observe the improvement of all the properties at the same time. The results also make possible to define the critical features to improve in order to use block copolymers as additive in hypromellose film coating. The availability of new water-soluble additives able to work as plasticizer and moisture sealer in polymeric films represents an important progress not only in the field of pharmaceutical coating but also in that of food coatings, as for example in the formulation of edible films

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“…For Poloxamer, it includes Amphipathic Poloxamer and Pluronic F127. Amphipathic Poloxamer, a FDA‐approved triblock polymer, composes of hydrophobic poly(ethylene oxide) and hydrophilic poly(propylene oxide) components . Hydrogel based on this has been widely used in both therapeutic and consumer applications.…”

Section: Introductionmentioning

confidence: 99%

Biodegradable Polyester Thermogelling System as Emerging Materials for Therapeutic Applications

Shan

Liu

2018

Macro Materials & Eng

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In situ forming hydrogels are systems responsive to the environmental stimuli, such as change of temperature, pH, photo intensity, ionic strength, etc. [14,15] They have been divided into two types, one is chemical in situ gels and the other is physical in situ gels. Chemical in situ gels, also called "permanent" gels, are hydrogels containing covalently cross-linked networks. They are irreversible polymeric networks via the use of cross-linkers or enzymes. [16] Physical in situ gels, or "reversible" gels, are those networks held together by molecular entanglements and secondary forces such as hydrogen bonding, ionic, hydrophobic forces. [17,18] Usually these weak and reversible bonds formation depends on external stimulation to form cross-linking, which makes temperature, pH, lights, or ions sensitive reversible hydrogels possible. [19][20][21][22] In situ delivery systems have an upper hand compared with conventional systems, because they take longer time for in situ system to finish releasing drug at targeted site. Particularly, a temperature responsive hydrogel, namely thermogel, is a reversible physical cross-linking system, forming upon heating up temperature until critical temperature. The properties of thermogel offer opportunities in therapeutic application because of several reasons. [23][24][25] An injectable thermogel system has simplicity of pharmaceutical formulation by mixing of drug below sol-gel transition temperature. Large scale surgery for implantation is not needed. After injection, body temperature will stimulate sol-gel transition, viscous solution will change into a drug delivery depot. The high percentage water content makes thermogel highly competitive with the injection site. Also, peptides are kept at low temperature before application, which makes sure no denaturalization due to organic solvent interaction or dissolution triggered by high temperature.Currently, there are only two types of commercial polymeric thermoresponsive hydrogel products available in the market. One is Poloxamer, and the other is poly(N-isopropyl acrylamide) (PNIPAAm). When using Poloxamer based hydrogel, two conditions, polymer critical micelle concentration (CMC) and critical micelle temperature (CMT), must be reached to promote sol-gel transition. For Poloxamer, it includes Amphipathic Poloxamer and Pluronic F127. Amphipathic Poloxamer, a FDA-approved triblock polymer, composes of hydrophobic poly(ethylene oxide) and hydrophilic poly(propylene oxide) components. [26] Hydrogel based on this has been widely used in both therapeutic and consumer applications. Although Amphipathic Poloxamer has proven to be biocompatible and able to perform drug delivery, [27] degradation of it based hydrogels does not support sustainable Therapeutic Applications Polyesters comprise the earliest and most extensive investigation as biomaterials. The integration of polyester into thermogelling system is one of the most recent trends in the development of hydrogel research. In this review, the most recent development of polyester ba...

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Poloxamer Thermogel Systems as Medium for Crystallization

Abstract: Poloxamer is a very interesting polymer in that it is able to generate a reversible gelling medium from which crystals can be harvested by filtering, without the addition of any chemicals to promote the sol-gel transition.

Cited by 18 publications

References 20 publications

Viscous hydrophilic injection matrices for serial crystallography

Viscous hydrophilic injection matrices for serial crystallography

Evaluation of methoxy polyethylene glycol‐polylactide diblock copolymers as additive in hypromellose film coating

Biodegradable Polyester Thermogelling System as Emerging Materials for Therapeutic Applications

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