Synthesis of hybrid linear-dendritic block copolymers with carboxylic functional groups for the biomimetic mineralization of calcium carbonate

Using phenolic polymers to control the size and morphology of calcium carbonate microparticles

Calcium carbonate (CaCO3) is a naturally occurring mineral that occurs in biology and is used industrially. Due to its benign nature, CaCO3 microparticles have found use in the food and medical fields, where the specific size of the microparticles determine their functionality and potential applications. We demonstrate that phenolic polymers with different numbers of hydroxy groups can be used to control the diameter of CaCO3 microparticles in a range of 2-9 μm, and obtained particles were relatively uniform. The largest particles (∼9 μm in diameter) were obtained using poly(2,3,4,5-tetrahydroxystyrene) (P4HS), which showed the highest water solubility among the tested phenolic polymers. The polymer concentration and stirring speed influenced the size of microparticles, where the size of the obtained particles became smaller as the concentrations of phenolic polymers increased and as the stirring speed increased, both likely due to promoting the formation of a large number of individual crystal seeds by shielding seed-seed fusion and increasing the chances for precursor contact, respectively. The preparation time and temperature had a great influence on the morphology of the CaCO3 particles, where vaterite transforms into calcite over time. Specifically, aragonite crystals were observed at preparation temperature of 80 °C and vaterite particles with rough surfaces were obtained at 40 °C. Molecular weight and scale of reaction were also factors which affect the size and morphologies of CaCO3 particles. This research represents a facile method for producing relatively monodisperse CaCO3 microparticles with diameters that have previously proven difficult to access.

Phase separation in polymer-based biomimetic structures containing planar membranes

Phase separation in biological membranes is crucial for proper cellular functions, such as signaling and trafficking, as it mediates the interactions of condensates on membrane-bound organelles and transmembrane transport to targeted destination compartments. The separation of a lipid bilayer into phases and the formation of lipid rafts involve the restructuring of molecular localization, their immobilization, and local accumulation. By understanding the processes underlying the formation of lipid rafts in a cellular membrane, it is possible to reconstitute this phenomenon in synthetic biomimetic membranes, such as hybrids of lipids and polymers or membranes composed solely of polymers, which offer an increased physicochemical stability and unlimited possibilities of chemical modification and functionalization. In this article, we relate the main lipid bilayer phase transition phenomenon with respect to hybrid biomimetic membranes, composed of lipids mixed with polymers, and fully synthetic membranes. Following, we review the occurrence of phase separation in biomimetic hybrid membranes based on lipids and/or direct lipid analogs, amphiphilic block copolymers. We further exemplify the phase separation and the resulting properties and applications in planar membranes, free-standing and solid-supported. We briefly list methods leading to the formation of such biomimetic membranes and reflect on their improved overall stability and influence on the separation into different phases within the membranes. Due to the importance of phase separation and compartmentalization in cellular membranes, we are convinced that this compiled overview of this phenomenon will be helpful for any researcher in the biomimicry area.

One-step phosphorylated poly(amide-amine) dendrimer loaded with apigenin for simultaneous remineralization and antibacterial of dentine

Dental caries, starting from demineralization of enamel and dentine, is closely related with acid-producing bacteria in oral cavity, for example, Streptococcus mutans. Remineralization is an efficient way to prevent the disease progression and facilitate the therapy of incipient caries. Therefore, for the purpose of effective dentine repair, remineralization and antibacterial should be combined simultaneously. However, most of the literatures only focus on one single aspect, while combing remineralization and antibacteria for dentine repair in one system is rarely reported. Here in this work, phosphoryl-terminated poly(amide-amine) dendrimers were loaded with apigenin, a water-nonsoluble drug antibacterial agains Streptococcus mutans. The apigenin-loaded dendrimers bind strongly with dentine, which further induce dentine tubules occlusion through mineralization in artificial saliva, and the release of apigenin can prevent further erosion of dentine by bacteria. Meanwhile, the phosphorylated dendrimers are easily prepared by one-step modification of poly(amide-amine) and exhibit good cytocompatibility. This strategy developed here can provide reference for the design of effective anti-caries materials.

Preparation and characterization of PSF/PEI/CaCO3 nanocomposite membranes for oil/water separation

Ultrafiltration (UF) is one of the significant advanced processes for oily wastewater treatment due to its clear advantages, for instance, ease in operation and efficient separation. The main drawback of these processes is the fouling problem and many researchers' effort on fabrication of high-performance membranes with higher hydrophilicity and antifouling properties. In this study, flat-sheet polysulfone (PSF)/polyethylenimine (PEI)/CaCO₃ nanocomposite membranes were prepared by phase inversion method for oil/water emulsion separation. Structural properties of membranes were characterized by SEM, FT-IR, contact angle, tensile strength, and atomic force microscopy analysis. Increasing the CaCO₃ nanoparticle loading exhibited the increased the water flux and BSA rejection. PSF/PEI/10 wt% CaCO₃ nanocomposite membranes have 145 L/m² h water flux at 2 bar with a contact angle of 84° and with 92% BSA rejection. All prepared CaCO₃ nanocomposite membranes reached similar oil rejections at above 90%. Besides the higher water flux and oil removal efficiencies, 10 wt% of CaCO₃ nanoparticle-blended PSF membranes has notable antifouling capacity with the highest flux recovery ratio (FRR) and lowest flux decay ratio (DR) values. The results showed that there is a great potential to use PSF/PEI/CaCO₃ nanocomposite membranes for the treatment of oil water emulsions with higher permeability and antifouling capacity.

Biodegradable dendrimers for drug delivery

Dendrimers, as a type of artificial polymers with unique structural features, have been extensively explored for their applications in biomedical fields, especially in drug delivery. However, one important concern about the most commonly used dendrimers exists - the nondegradability, which may cause side effects induced by the accumulation of synthetic polymers in cells or tissues. Therefore, biodegradable dendrimers incorporating biodegradability with merits of dendrimers such as well-defined architectures, copious internal cavities and surface functionalities, are much more promising for developing novel nontoxic drug carriers. Herein, we review the recent advances in design and synthesis of biodegradable dendrimers, as well as their applications in fabricating drug delivery systems, with the aim to provide researchers in the related fields a good understanding of biodegradable dendrimers for drug delivery.

Linear-dendritic block copolymers as a green scale inhibitor for calcium carbonate in cooling water systems

Water-soluble monomer APEG-PG-(OH)n were produced and the Structure of APEG-PG-(OH)5 were identified by ¹H-NMR. APEG-PG-(OH)n were copolymerized with maleic anhydride (MA) to synthesize no phosphate and nitrogen free calcium carbonate inhibitor MA/APEG-PG-(OH)n. The structure and thermal property of MA/APEG-PG-(OH)5 were characterized and measured by ¹H-NMR, GPC and TGA. The observation shows that the dosage and n value of MA/APEG-PG-(OH)n plays an important role on CaCO₃ inhibition. MA/APEG-PG-(OH)5 displays superior ability to inhibit the precipitation of calcium carbonate, with approximately 97% inhibition at a level of 8 mg/L. The effect on formation of CaCO₃ was investigated with combination of SEM and XRD analysis.

Bioinspired fabrication of macroporous calcium carbonate crystals mediated by thermoresponsive copolymers

Scheme showing the growth mechanism of the CaCO₃ crystals at 50 °C.

The Present and the Future of Degradable Dendrimers and Derivatives in Theranostics

Interest in dendrimer-based nanomedicines has been growing recently, as it is possible to precisely manipulate the molecular weight, chemical composition, and surface functionality of dendrimers, tuning their properties according to the desired biomedical application. However, one important concern about dendrimer-based therapeutics remains-the nondegradability under physiological conditions of the most commonly used dendrimers. Therefore, biodegradable dendrimers represent an attractive class of nanomaterials, since they present advantages over conventional nondegradable dendrimers regarding the release of the loaded molecules and the prevention of bioaccumulation of synthetic materials and subsequent cytotoxicity. Here, we present an overview of the state-of-the-art of the design of biodegradable dendritic structures, with particular focus on the hurdles regarding the use of these as vectors of drugs and nucleic acids, as well as macromolecular contrast agents.

Recent developments and applications of bioinspired dendritic polymers

This review highlights the bioinspired applications of dendritic polymers, focusing on their structure–function relationship to natural biomolecules such as proteins.

Calcite nucleation on the surface of PNIPAM–PAAc micelles studied by time resolved in situ PXRD

Nanocrystalline calcite is formed under the influence of block copolymers containing thermoresponsive PNIPAM and a mineralization controlling block of poly(acrylic acid) and the nanocrystal formation kinetics studied by in situ X-ray diffraction.

Dendritic architectures based on bis-MPA: functional polymeric scaffolds for application-driven research

Dendritic polymers are highly branched, globular architectures with multiple representations of functional groups. These nanoscale organic frameworks continue to fascinate researchers worldwide and are today under intensive investigation in application-driven research. A large number of potential application areas have been suggested for dendritic polymers, including theranostics, biosensors, optics, adhesives and coatings. The transition from potential to real applications is strongly dictated by their commercial accessibility, scaffolding ability as well as biocompatibility. A dendritic family that fulfills these requirements is based on the 2,2-bismethylolpropionic acid (bis-MPA) monomer. This critical review is the first of its kind to cover most of the research activities generated on aliphatic polyester dendritic architectures based on bis-MPA. It is apparent that these scaffolds will continue to be in the forefront of cutting-edge research as their structural variations are endless including dendrons, dendrimers, hyperbranched polymers, dendritic-linear hybrids and their hybridization with inorganic surfaces.

New developments in polymer-controlled, bioinspired calcium phosphate mineralization from aqueous solution

The polymer-controlled and bioinspired precipitation of inorganic minerals from aqueous solution at near-ambient or physiological conditions avoiding high temperatures or organic solvents is a key research area in materials science. Polymer-controlled mineralization has been studied as a model for biomineralization and for the synthesis of (bioinspired and biocompatible) hybrid materials for a virtually unlimited number of applications. Calcium phosphate mineralization is of particular interest for bone and dental repair. Numerous studies have therefore addressed the mineralization of calcium phosphate using a wide variety of low- and high-molecular-weight additives. In spite of the growing interest and increasing number of experimental and theoretical data, the mechanisms of polymer-controlled calcium phosphate mineralization are not entirely clear to date, although the field has made significant progress in the last years. A set of elegant experiments and calculations has shed light on some details of mineral formation, but it is currently not possible to preprogram a mineralization reaction to yield a desired product for a specific application. The current article therefore summarizes and discusses the influence of (macro)molecular entities such as polymers, peptides, proteins and gels on biomimetic calcium phosphate mineralization from aqueous solution. It focuses on strategies to tune the kinetics, morphologies, final dimensions and crystal phases of calcium phosphate, as well as on mechanistic considerations.

Double-Hydrophilic Block Copolymer as an Effective and Environmentally Friendly Inhibitor for Phosphate and Carbonate Scales in Cooling Water Systems

In this paper, a series of linear-dendritic block copolymers allyloxy poly(ethylene glycol) polyglycerol (APEG-PG-(OH)n) copolymer, was synthesized by anionic polymerization of glycerol using allyloxy poly(ethylene glycol) (APEG). The polymers were characterized by FT-IR and 1H NMR. The polymers were tested as novel environment-friendly inhibitors for industrial cooling water circulation. The performance of AA/APEG-PG-(OH)n on inhibition of calcium phosphate and calcium carbonate precipitation was studied by static scale inhibition tests. It was shown that AA/APEG-PG-(OH)n exhibited excellent ability to control inorganic minerals, with approximately 99 % calcium phosphate inhibition and 85 % calcium carbonate inhibition at levels of 4 and 10 mg/L AA/APEG-PG-(OH)n, respectively. The effect on formation of calcium phosphate and calcium carbonate was investigated with combination of scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) analysis, respectively.