The shortage of water resources and increasingly serious water pollution have driven the development of high-efficiency water treatment technology. Among a variety of technologies, adsorption is widely used in environmental remediation. As a class of typical adsorbents, metal oxides have been developed for a long time and continued to attract widespread attention, since they have unique physicochemical properties, including abundant surface active sites, high chemical stability, and adjustable shape and size. In this review, the basic principles of the adsorption process will be first elucidated, including affecting factors, evaluation index, adsorption mechanisms, and common kinetic and isotherm models. Then, the adsorption properties of several typical metal oxides, and key parameters affecting the adsorption performance such as particle/pore size, morphology, functionalization and modification, supports and calcination temperature will be discussed, as well as their application in the removal of various inorganic and organic contaminants. In addition, desorption and recycling of the spent adsorbent are summarized. Finally, the future development of metal oxide based adsorbents is also discussed.

Rational design, synthesis, adsorption principles and applications of metal oxide adsorbents: a review.

Polypeptides have attracted considerable attention in recent decades due to their inherent biodegradability and tunable cytocompatibility. Macromolecular design in conjunction with rational monomer composition can direct architecture, self-assembly and chemical behavior, ultimately guiding the choice of appropriate application within the biomedical field. This review focuses on the applications of polypeptides alongside the synthetic advances in the ring opening polymerization of α-amino acid N-carboxyanhydrides achieved in the past five years. Key architectures obtained through NCA ROP or in combination with other polymerization methods are reviewed, as these play an important role in the wide range of applications towards which polypeptides have been applied.

Ring opening polymerization of α-amino acids: advances in synthesis, architecture and applications of polypeptides and their hybrids.

Heparin is the highest negatively charged biomolecule, which is a polysaccharide belonging to the glycosaminoglycan family, and its role as a regulator of various proteins, cells and tissues in the human body makes it an indispensable macromolecule. Heparin-based hydrogels are widely investigated in various applications including implantation, tissue engineering, biosensors, and drug-controlled release due to the 3D-constructs of hydrogels. However, heparin has supply and safety problems because it is usually derived from animal sources, and has the clinical limitations of bleeding and thrombocytopenia. Therefore, analogous heparin-mimicking polymers and hydrogels derived from non-animal and/or totally synthetic sources have been widely studied in recent years. In this review, the progress and potential biomedical applications of heparin-based and heparin-inspired hydrogels are highlighted. We classify the forms of these hydrogels by their size including macro-hydrogels, injectable hydrogels, and nano-hydrogels. Then, we summarize the various fabrication strategies for these hydrogels including chemical covalent bonding, physical conjugation, and the combination of chemical and physical interactions. Covalent bonding includes free radical polymerization of vinyl-containing components, amide bond formation reaction, Michael-type addition reaction, click-chemistry, divinyl sulfone crosslinking, and mussel-inspired coating. Hydrogels physically conjugated via host–guest interaction, electrostatic interaction, hydrogen bonding, and hydrophobic interaction are also discussed. Finally, we conclude with the challenges and future directions for the fabrication and the industrialization of heparin-based and heparin-inspired hydrogels. We believe that this review will attract more attention toward the design of heparin-based and heparin-inspired hydrogels, leading to future advancements in this emerging research field.

Heparin-based and heparin-inspired hydrogels: size-effect, gelation and biomedical applications

Targeting drug delivery with light: A highly focused approach.

Fast drug delivery is very important to utilize drug molecules that are short-lived under physiological conditions. Techniques that can release model molecules under physiological conditions could play an important role to discover the pharmacokinetics of short-lived substances in the body. Here an experimental method is developed for the fast release of the liposomes’ payload without a significant increase in (local) temperatures. This goal is achieved by using short magnetic pulses to disrupt the lipid bilayer of liposomes loaded with magnetic nanoparticles. The drug release has been tested by two independent assays. The first assay relies on the AC impedance measurements of MgSO₄ released from the magnetic liposomes. The second standard release assay is based on the increase of the fluorescence signal from 5(6)-carboxyfluorescein dye when the dye is released from the magneto liposomes. The efficiency of drug release ranges from a few percent to up to 40% in the case of the MgSO₄. The experiments also indicate that the magnetic nanoparticles generate ultrasound, which is assumed to have a role in the release of the model drugs from the magneto liposomes.

Pulsed Magnetic Field Induced Fast Drug Release from Magneto Liposomes via Ultrasound Generation

Improved synthesis of graphene oxide with controlled oxidation degree by using different dihydrogen phosphate as intercalators

https://iopscience.iop.org/article/10.1088/2053-1591/ab253e/pdf

Preparation and properties of a temperature- and pH- responsive polypeptide hydrogel

To improve the release profile of peptide drugs, thermos-responsive triblock copolymer poly (e-caprolactone-co-p-dioxanone)-b-poly (ethylene glycol)-b-poly (e-caprolactone-co-p-dioxanone) (PECP) was prepared and end capped by succinic anhydride to give its carboxylic terminated derivative. Both PCEP block copolymer and its end group modified derivative showed temperature-dependent reversible sol-gel transition in water. The carboxylic end group could significantly decrease the sol-gel transition temperature by nearly 10 °C and strengthen the gel due to enhanced intermolecular force among triblock copolymer chains. Furthermore, compared with the original PECP triblock copolymer, HOOC–PECP–COOH copolymer displayed a retarded and sustained release profile for leuprorelin acetate over one month while effectively avoiding the initial burst. The controlled release was believed to be related to the formation of conjugated copolymer-peptide pair by ionic interaction and enhanced solubility of drug molecules into the hydrophobic domains of the hydrogel. Therefore, carboxyl terminated HOOC–PECP–COOH hydrogel was a promising and well-exhibited sustained release carrier for peptide drugs with the advantage of being able to develop injectable formulation by simple mixing.

https://www.mdpi.com/1996-1944/11/3/338/pdf

Carboxylic Terminated Thermo-Responsive Copolymer Hydrogel and Improvement in Peptide Release Profile

Synthesis and characterization of photo-responsive flower-like copolymer micelles with o-nitrobenzyl as the junction point

Magnetically driven drug delivery systems of superparamagnetic iron oxide nanoparticles have a considerable potential as candidates to overcome the present obstacles of drug delivery in anti-tumor therapy owing to its remote controllability by external magnetic fields and other unique properties. In this work, a biodegradable anionic copolymer with side carboxylic groups named methoxy-poly (ethylene glycol)-block-poly(α-carboxyl-e-caprolactone) was synthesized to complex iron oxide magnetic nanoparticles and load paclitaxel (PTX) to form dual-stimuli responsive copolymer-magnetite superparamagnetic nanocomposites with an elastic core and carboxylic groups on the surface in a very easy way. The physiochemical properties of these nanocomposites were measured. High PTX loading content and high saturation magnetization were obtained. Being proved to be stable at a wide pH range and low cytotoxic in vitro, these nanocomposites presented faster PTX release in vitro at pH 6.5 than at pH 7.4 and obviously reduced burst release.

https://iopscience.iop.org/article/10.1088/1361-6528/aaf9ec/pdf

Hongyu Zhu

Papers

Improved synthesis of graphene oxide with controlled oxidation degree by using different dihydrogen phosphate as intercalators

Preparation and properties of a temperature- and pH- responsive polypeptide hydrogel

Carboxylic Terminated Thermo-Responsive Copolymer Hydrogel and Improvement in Peptide Release Profile

Synthesis and characterization of photo-responsive flower-like copolymer micelles with o-nitrobenzyl as the junction point

Physiochemical properties and paclitaxel release behaviors of dual-stimuli responsive copolymer-magnetite superparamagnetic nanocomposites.