Complex poly(ε-caprolactone)/poly(ethylene glycol) copolymer architectures and their effects on nanoparticle self-assembly and drug nanoencapsulation

Design of fluorinated stealth poly(ε-caprolactone) nanocarriers

The covalent functionalization of polymers with fluorinated moieties represents a promising strategy for the development of multimodal systems. Moreover, polymer fluorination often endows the resulting nanocarriers with improved colloidal stability in the biological environment. In this work, we developed fluorinated pegylated (PEG) biodegradable poly(ε-caprolactone) (PCL) drug nanocarriers showing both high colloidal stability and stealth properties, as well as being (19F)-Nuclear Magnetic Resonance (NMR) detectable. The optimized nanocarriers were obtained mixing a PEG-PCL block copolymer with a nonafluoro-functionalized PCL polymer. The role of PEGylation and fluorination on self-assembly and colloidal behavior of the obtained nanoparticles (NPs) was investigated, as well as their respective role on stealth properties and colloidal stability. To prove the feasibility of the developed NPs as potential 19F NMR detectable drug delivery systems, a hydrophobic drug was successfully encapsulated, and the maintenance of the relevant 19F NMR properties evaluated. Drug-loaded fluorinated NPs still retained a sharp and intense 19F NMR signal and good relaxivity parameters (i.e., T1 and T2 relaxation times) in water, which were not impaired by drug encapsulation.

Recent Advances in the Application of ATRP in the Synthesis of Drug Delivery Systems

Advances in atom transfer radical polymerization (ATRP) have enabled the precise design and preparation of nanostructured polymeric materials for a variety of biomedical applications. This paper briefly summarizes recent developments in the synthesis of bio-therapeutics for drug delivery based on linear and branched block copolymers and bioconjugates using ATRP, which have been tested in drug delivery systems (DDSs) over the past decade. An important trend is the rapid development of a number of smart DDSs that can release bioactive materials in response to certain external stimuli, either physical (e.g., light, ultrasound, or temperature) or chemical factors (e.g., changes in pH values and/or environmental redox potential). The use of ATRPs in the synthesis of polymeric bioconjugates containing drugs, proteins, and nucleic acids, as well as systems applied in combination therapies, has also received considerable attention.

Synthesis of High-Molecular-Weight Bifunctional Additives with both Flame Retardant Properties and Antistatic Properties via ATRP

Polystyrene (PS) is widely used in our daily life, but it is flammable and produces a large number of toxic gases and high-temperature flue gases in the combustion process, which limit its application. Improving the flame retardancy of PS has become an urgent problem to be solved. In addition, in view of the disadvantage that small-molecule flame retardants can easily migrate from polymers during use, which leads to the gradual reduction of the flame retardant effect or even loss of flame retardant performance, and the outstanding advantages of ATRP technology in polymer structure design and function customization, we used ATRP technology to synthesize the high-molecular-weight bifunctional additive PFAA-DOPO-b-PDEAEMA, which has flame retardant properties and antistatic properties. The chemical structure and molecular weight of PFAA-DOPO-b-PDEAEMA were characterized by FTIR, ¹H NMR, GPC, and XPS. When the addition of PFAA-DOPO-b-PDEAEMA was 15 wt %, the limiting oxygen index (LOI) of polystyrene composites was 28.4%, which was 53.51% higher than that of pure polystyrene, the peak of the heat release rate (pHRR) was 37.61% lower than that of pure polystyrene, UL-94 reached V-0 grade, and the flame retardant index (FRI) was 2.98. In addition, when the PFAA-DOPO-b-PDEEMA content is 15 wt %, the surface resistivity and volume resistivity of polystyrene composites are 2 orders of magnitude lower than those of polystyrene. This research work provides a reference for the design of bifunctional and even multifunctional polymers.

In-situ formation of fluorophore cross-linked micellar thick films and usage as drug delivery material for Propranolol HCl

Polyethylene glycol monomethyl ether-block-poly(glycidyl methacrylate)-block-poly[2-(diethylamino)ethyl methacrylate] triblock copolymer was synthesized to prepare self-assembled micron sized films via a novel approach named as "phase separated micellar self assembly method". Liquid-air interface self assembly method via slow solvent evaporation was used to obtain micellar films. Cross-linking of polymer films was carried out by diffusion of fluorophore cross-linker into polymer solution from subphase. In-situ micellar formation was triggered via driven forces such as molecular interactions and slow evaporation of solvent. Thiazolo[5,4-d]thiazole based cross-linker fluorophores containing alkali subphases were used to prepare highly fluorescent cross-linked micellar films. Micellar morphologies of the films were characterized with SEM while the cross-sections of fluorophore cross-linked films were observed with TEM analysis to examine diffusion of the dye as nano-sized particles into the polymer film. Convenience and usability of the micellar films as drug delivery material were demonstrated with Propranolol HCl release via UV-Vis spectroscopic studies. Optical properties of the films before and after drug release were determined via photoluminescence spectroscopy to be able to sense the completion of the drug release process. Swelling and shrinkage properties of the films were also determined in different pH values. These highly fluorescent polymer films have great potential as drug delivery materials and biomedical sensing applications.