Multiarm Core Cross-Linked Star-Shaped Poly(2-oxazoline)s Using a Bisfunctional 2-Oxazoline Monomer

Highly Sensitive Temperature Sensing in Biological Region with Ratiometric Fluorescent Response

Poly(2-oxazoline) (POx), a typical thermoresponsive polymer with good biocompatibility, was conjugated with environment-sensitive tetraphenylenethene (TPE) and hydroxyphenylbenzoxazole (HBO) to achieve unique thermometer readings. Through phase transition induced by temperature, the thermometers can measure temperature in biologic range with ratiometric fluorescence response, ultrahigh sensitivity and good reversibility. Moreover, the thermometer can be used to measure the change in temperature with large fluorescence difference in living cells.

A Review of the Synthesis of Oxazoline Derivatives

Oxazolines are important heterocyclic systems due to their biological activities, such as antibacterial, antimalarial, anticancer, antiviral, anti-inflammatory, antifungal, antipyretic, and antileishmanial. They have been widely applied as chiral auxiliaries, polymers, catalysts, protecting groups, building blocks, and ligands in asymmetric synthesis. Due to their importance, many synthetic routes to prepare oxazoline moieties have been investigated and developed by researchers around the world. In this review, we summarized several synthetic methodologies published in the literature. The main substrates are nitriles, carboxylic acids, and acid derivatives, which react with a variety of reactants under conventional heating, microwave irradiation or ultrasound irradiation conditions. Syntheses via intramolecular cyclisation from amides have also been reported. Many publications have highlighted procedures based on solvent-free conditions using eco-friendly, reusable, and easy-availability catalysts.

Poly(2-oxazoline)-based core cross-linked star polymers: synthesis and drug delivery applications

Poly(2-oxazoline)s (POxs) are promising platforms for drug delivery applications due to their biocompatibility and stealth properties. In addition, the use of core cross-linked star (CCS) polymers based on POxs is expected to enhance drug encapsulation and release performances. In this study, we employed the "arm-first" strategy to synthesize a series of amphiphilic CCS [poly(2-methyl-2-oxazoline)]_n-block-poly(2,2'-(1,4-phenylene)bis-2-oxazoline)-cross-link/copolymer-(2-n-butyl-2-oxazoline)s (PMeOx)_n-b-P(PhBisOx-cl/co-ButOx)s by using microwave-assisted cationic ring-opening polymerization (CROP). First, PMeOx, as the hydrophilic arm, was synthesized by CROP of MeOx using methyl tosylate as the initiator. Subsequently, the living PMeOx was used as the macroinitiator to initiate the copolymerization/core-crosslinking reaction of ButOx and PhBisOx to form CCS POxs having a hydrophobic core. The molecular structures of the resulting CCS POxs were characterized by size exclusion chromatography and nuclear magnetic resonance spectroscopy. The CCS POxs were loaded with the anti-cancer drug doxorubicin (DOX), and the loading was detected by UV-vis spectrometry, dynamic light scattering, and transmission electron microscopy. In vitro studies showed that DOX release at pH 5.2 was faster than that at pH 7.1. The in vitro cytotoxicity study using HeLa cells revealed that the neat CCS POxs are compatible with the cells. In contrast, the DOX-loaded CCS POxs exhibited a cytotoxic effect in a concentration-dependent manner in HeLa cells, which strongly supports that the CSS POxs are potential candidates for drug delivery applications.

Protected amine-functional initiators for the synthesis of α-amine homo- and heterotelechelic poly(2-ethyl-2-oxazoline)s

Screening a series of protected amine cationic ring-opening polymerization initiators revealed the commercially available N-(3-bromopropyl)phthalimide as the most suitable to achieve defined polymers with high degree of amine functionalization.

Degradable thiomethacrylate core-crosslinked star-shaped polymers

Degradable polymers are considered to present a promising solution to combat plastic pollution. However, many polymers are based on ester and amide bonds, which often require high temperatures and acidic/basic...