Smart microgels as drug delivery vehicles for the natural drug aescin: uptake, release and interactions

Dirksen, Maxim; Dargel, Carina; Meier, Lukas; Brändel, Timo; Hellweg, Thomas

doi:10.1007/s00396-020-04632-5

Cited by 47 publications

(46 citation statements)

References 64 publications

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“…Their increasing popularity can be attributed to their responsiveness towards external stimuli such as temperature or pH, which is achieved by polymerizing certain monomers such as acrylamides and weak acids or bases [ 9 , 10 , 11 , 12 , 13 , 14 ] and due to their tunability in size [ 15 ] and architecture [ 16 , 17 , 18 , 19 ]. A rapid change in size upon changing these stimuli enables a vast variety of possible applications in the fields of catalysis, sensing, drug targeting, surface-functionalization or bio-conjugation [ 7 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. The latter is often mentioned together with cationic nano- and microgels that are far less studied than their anionic counterparts [ 25 ].…”

Section: Introductionmentioning

confidence: 99%

Importance of pH in Synthesis of pH-Responsive Cationic Nano- and Microgels

2021

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While cationic microgels are potentially useful for the transfection or transformation of cells, their synthesis has certain drawbacks regarding size, polydispersity, yield, and incorporation of the cationic comonomers. In this work, a range of poly(N-isopropylacrylamide) (PNIPAM) microgels with different amounts of the primary amine N-(3-aminopropyl)methacrylamide hydrochloride (APMH) as the cationic comonomer were synthesized. Moreover, the pH-value during reaction was varied for the synthesis of microgels with 10 mol% APMH-feed. The microgels were analyzed by means of their size, thermoresponsive swelling behavior, synthesis yield, polydispersity and APMH-incorporation. The copolymerization of APMH leads to a strong decrease in size and yield of the microgels, while less than one third of the nominal APMH monomer feed is incorporated into the microgels. With an increase of the reaction pH up to 9,5 , the negative effects of APMH copolymerization were significantly reduced. Above this pH, synthesis was not feasible due to aggregation. The results show that the reaction pH has a strong influence on the synthesis of pH-responsive cationic microgels and therefore it can be used to tailor the microgel properties.

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Section: Introductionmentioning

confidence: 99%

Importance of pH in Synthesis of pH-Responsive Cationic Nano- and Microgels

2021

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“…Regarding the use of microgels as drug-delivery vehicles, many different studies have been performed with varying drugs, ranging from lysozyme [ 24 ] over the more hydrophilic drugs dopamine, naproxen, desipramine, dibucaine, acetaminophen [ 25 ], and

-aescin [ 26 ] to the hydrophobic doxorubicin (DOX) [ 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. Just from these representative examples, it can be stated that the structure of microgels, which often exhibit a rather hydrophobic, cross-linker rich core region and a rather hydrophilic corona [ 34 ], enables these particles to act as carriers for a variety of hydrophilic and hydrophobic drugs.…”

Section: Introductionmentioning

confidence: 99%

“…In this context, a good loading is achieved, and the drug is released slowly from the carrier system without the active ingredient being adversely affected. Compared to Kataokas approach, microgels could potentially be advantageous for such an application, as their ability to react to external stimuli such as temperature [ 26 ] or pH [ 36 ] can be easily utilized to realize a targeted release of active ingredients with the highest possible precision. One of the most remarkable examples in this context is probably the novel drug cannabidiol (CBD) [ 37 ], which is often applied after being dissolved in olive oil.…”

Section: Introductionmentioning

confidence: 99%

Temperature Controlled Loading and Release of the Anti-Inflammatory Drug Cannabidiol by Smart Microgels

Dirksen

Kinder²,

Brändel

et al. 2021

Molecules

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CBD is a promising candidate for treatment of many diseases and plays a major role in the growing trend to produce high-end drugs from natural, renewable resources. In the present work, we demonstrate a way to incorporate the anti-inflammatory drug CBD into smart microgel particles. The copolymer microgels that we chose as carrier systems exhibit a volume phase transition temperature of 39 ∘C, which is just above normal body temperature and makes them ideal candidates for hyperthermia treatment. While a simple loading route of CBD was not successful due to the enormous hydrophobicity of CBD, an alternative route was developed by immersing the microgels in ethanol. Despite the expected loss of thermoresponsive behaviour of the microgel matrix due to the solvent exchange, a temperature-dependent release of CBD was detected by the material, creating an interesting question of interactions between CBD and the microgel particles in ethanol. Furthermore, the method developed for loading of the microgel particles with CBD in ethanol was further improved by a subsequent transfer of the loaded particles into water, which proves to be an even more promising approach due to the successful temperature-dependent release of the drug above the collapse temperature of the microgels.

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“…of Chemistry, Physical and Biophysical Chemistry, Bielefeld University, Universitätsstr. 25, 33615Bielefeld, Germany which is of great interest in various fields, like controlled catalysis [11,12], biocatalysis [13,14], sensor design [15][16][17][18], drug delivery [19,20], microreactors [21], smart membrane fabrication [22,23], surface coating [24,25] and microfluidics [26][27][28]. The properties of microgels can be influenced by copolymerization [29] or by architecture [30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Acrylamide precipitation polymerization in a continuous flow reactor: an in situ FTIR study reveals kinetics

et al. 2020

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In this work, we present a combination of a continuous flow reactor with in situ monitoring of the monomer conversion in a precipitation polymerization. The flow reactor is equipped with a preheating area for the synthesis of thermoresponsive microgels, based on N-isopropylacrylamide (NIPAM). The reaction progress is monitored with in situ FTIR spectroscopy. The monomer conversion at defined residence times is determined from absorbance spectra of the reaction solutions by linear combination with reference spectra of the stock solution and the purified microgel. The reconstruction of the spectra appears to be in good agreement with experimental data in the range of 1710 to 1530 cm− 1, in which prominent absorption bands are used as probes for the monomer and the polymer. With increasing residence time, we observed a decrease in intensity of the ν(C=C) vibration, originating from the monomer, while the ν(C=O) vibration is shifted to higher frequencies by polymerization. Differences between the determined inline conversion kinetics and offline growth kinetics, determined by photon correlation spectroscopy (PCS), are discussed in terms of diffusion and point to a crucial role of mixing in precipitation polymerizations.

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Smart microgels as drug delivery vehicles for the natural drug aescin: uptake, release and interactions

Cited by 47 publications

References 64 publications

Importance of pH in Synthesis of pH-Responsive Cationic Nano- and Microgels

Importance of pH in Synthesis of pH-Responsive Cationic Nano- and Microgels

Temperature Controlled Loading and Release of the Anti-Inflammatory Drug Cannabidiol by Smart Microgels

Acrylamide precipitation polymerization in a continuous flow reactor: an in situ FTIR study reveals kinetics

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