Polymer microgels in the size range from several micrometers to hundreds of micrometers are used in the pharmaceutical, cosmetics, nutrition, pesticide, and food industries, as well as in the encapsulation of cells. To date, a broad range of strategies for the generation of polymer microgels exist, however, these methods involve multistage processes, do not utilize biocompatible components or do not allow precise control of the dimensions and internal structure of the microgels. Recently, microfluidic strategies for the production of polymer particles have offered precise control over the shapes, morphologies, and size distributions of polymer colloids. This paper discusses the most recent results obtained by the authors in the area of the microfluidic production of biopolymer microgels. It provides a brief review of the microfluidic methods for the continuous synthesis and fabrication of microgels, sets the criteria for the successful microfluidic generation of biomicrogels, and describes two methods for the preparation of microgels by microfluidic means. The article concludes with a summary and an outlook.
Although nanoporous materials have been explored for controlling crystallization of polymorphs in recent years, polymorphism in confined environments is still poorly understood, particularly from a kinetic perspective, and the role of the local structure of the substrate has largely been neglected. Herein, we report the use of a novel material, polymer microgels with tunable microstructure, for controlling polymorph crystallization from solution and for investigating systematically the effects of nanoconfinement and interfacial interactions on polymorphic outcomes. We show that the polymer microgels can improve polymorph selectivity significantly. The polymorphic outcomes correlate strongly with the gel-induced nucleation kinetics and are very sensitive to both the polymer microstructure and the chemical composition. Further mechanistic investigations suggest that the nucleation-templating effect and the spatial confinement imposed by the polymer network may be central to achieving polymorph selectivity. We demonstrate polymer microgels as promising materials for controlling crystal polymorphism. Moreover, our results help advance the fundamental understanding of polymorph crystallization at complex interfaces, particularly in confined environments. 相似文献
The ultrasound-induced cleavage of covalent and non-covalent bonds to activate drugs (sonopharmacology) is a promising concept to gain control over the action of active pharmaceutical ingredients by an external trigger. Previously, linear polymer architectures bearing drug payloads were exploited for drug release by using the principles of polymer mechanochemistry. In this work, the carrier design is altered by the polymer topology to improve the ultrasound-triggered release of covalently anchored drugs from polymer scaffolds. We use microgels crosslinked by mechanoresponsive disulfides and copolymerized with Diels-Alder adducts of furylated payload molecules and acetylenedicarboxylate. Force-induced thiol formation induces a Michael-type addition liberating the payload from the microgels. The use of microgels significantly reduces sonication times compared to linear polymer chains and shields the cargo efficiently from non-triggered activation using ultrasound that produces inertial cavitation at a frequency of 20 kHz as model condition. 相似文献
One of the most promising strategies in anticancer therapies is the targeted delivery through malignancy-associated cellular markers. The design of new synthetic devices with enhanced stimuli-responsive sensitivity and targeting ligands is a promising field for the development of cancer-specific delivery systems. One of the pathways to achieve this aim is the chemical functionalization of nanodevices such as microgels. The p-nitrophenyl acrylate (NPA) is an active ester molecule with a group that can be easily cleavaged by the nucleophilic attack of species such as amines. This modification consists of an easy chemical reaction that leads to several types of functionalized microgels, which are originally made up of NPA as one of their constituent monomers.
Here is reported the chemical functionalization of NPA-based microgels by incorporating pH-sensitive functional groups and folic acid as a tumor targeting ligand into the same initial polymer network. For this purpose, microgels of p-nitrophenyl acrylate (NPA)-co-methacrylamide (MeAM) synthesized by precipitation polymerization, were modified with two different pyridine derivatives: 2-aminomethylpyridine (2-AMP) and 2-aminopyridine (2-AP), thus pH-sensitive microgels with acid pH swelling capacity were obtained. The equilibrium swelling behaviour was studied as a function of pH, ionic strength, copolymer composition and type of pyridine derivative. In addition, the microgels were derivatized with ethylene diamine, to obtain amino-functionalized microgels to which the folic acid was subsequently attached as the targeting ligand. As final step, pH-sensitive groups and folic acid were equimolarly attached to the polymer chains to obtain the fully functionalized microgels. 相似文献
In this research, a series of pH-responsive microgels based on acrylamide (AM), acrylic acid (AA) as the main monomers, and N,N′-methylenebisacrylamide as a divinyl cross-linking agent, have been prepared by inverse microemulsion polymerization. The effect of chemical composition of poly(acrylamide-co-acrylic acid) (P(AM-co-AA)) on hydrodynamic diameters, morphology, swelling ratios and pH-responsive behaviour and thermal properties of microgels were discussed. With an increase of the mole percentages of AA in the feed ratio, the microgels have higher swelling ratios. The TEM photographs show that the spherical morphology of the microgels are regular relatively. Comparing with PAM microgels, number-average diameters of P(AM-co-AA) microgels were larger because of the presence of AA chain segment in the polymer chain. Turbidities of microgels determined through UV–vis spectrophotometer indicate that the microgels exhibit favourable pH-responsive behaviour, and responsive pH value is related to the dissociation constant of AA. Moreover, thermal stable properties of microgels were confirmed by differential scanning calorimeter. It was observed that an increase in the mole percentages of AA in the feed ratio provided lower glass transition temperature and thermal decomposition temperature of pH-responsive microgels. 相似文献
We report a strategy for the production of materials with structural hierarchy. The approach employs polymer microgels as templates for the synthesis of semiconductor, metal, or magnetic nanoparticles (NPs). We show that NPs with predetermined dimensions and size-dependent properties can be synthesized by using a very delicate balance between the reaction conditions, the composition and the structure of microgel templates, and the concentration of NPs in the microgel. Postheat treatment of microgels doped with semiconductor nanoparticles reduces NP polydispersity and allows control of their photoluminescence. Microgel templates are particularly beneficial in the synthesis of polymer microspheres heavily loaded with monodisperse superparamagnetic Fe(3)O(4) NPs. Hybrid submicrometer-size microgels have promising potential applications in photonics, catalysis, and separation technologies. 相似文献
Microgels are water-swollen, crosslinked polymers that are widely used as colloidal building blocks in scaffold materials for tissue engineering and regenerative medicine. Microgels can be controlled in their stiffness, degree of swelling, and mesh size depending on their polymer architecture, crosslink density, and fabrication method—all of which influence their function and interaction with the environment. Currently, there is a lack of understanding of how the polymer composition influences the internal structure of soft microgels and how this morphology affects specific biomedical applications. In this report, we systematically vary the architecture and molar mass of polyethylene glycol-acrylate (PEG-Ac) precursors, as well as their concentration and combination, to gain insight in the different parameters that affect the internal structure of rod-shaped microgels. We characterize the mechanical properties and diffusivity, as well as the conversion of acrylate groups during photopolymerization, in both bulk hydrogels and microgels produced from the PEG-Ac precursors. Furthermore, we investigate cell-microgel interaction, and we observe improved cell spreading on microgels with more accessible RGD peptide and with a stiffness in a range of 20 kPa to 50 kPa lead to better cell growth. 相似文献