Synthesis of cleavable multi-functional mikto-arm star polymer by RAFT polymerization: example of an anti-cancer drug 7-ethyl-10-hydroxycamptothecin (SN-38) as functional moiety

Fluorescent Strategy for Direct Quantification of Arm Component in Mikto-Arm Star Copolymers

Fluorescent end-functional mikto-arm star copolymers were prepared by an “arm-first” approach mediated by a mixture of macro-RAFT agents. RAFT copolymerization of coumarin-POEGMA, boron-dipyrromethene (BODIPY)-PDMA and bisindolylmaleimide (BIM)-PNIPAM with different fluorophore-labeled...

Star polymers with acid-labile diacetal-based cores synthesized by aqueous RAFT polymerization for intracellular DNA delivery

Facile low temperature aqueous heterogeneous RAFT polymerization for preparation of novel star polymers with acid-labile diacetal-based cores for DNA delivery.

Microfluidic Manufacturing of SN-38-Loaded Polymer Nanoparticles with Shear Processing Control of Drug Delivery Properties

Two-phase gas-liquid microfluidic reactors provide shear processing control of SN-38-loaded polymer nanoparticles (SN-38-PNPs). We prepare SN-38-PNPs from the block copolymer poly(methyl caprolactone- co-caprolactone)- block-poly(ethylene oxides) (P(MCL- co-CL)- b-PEO) using bulk and microfluidic methods and at different drug-to-polymer loading ratios and on-chip flow rates. We show that, as the microfluidic flow rate ( Q) increases, encapsulation efficiency and drug loading increase and release half times increase. Slower SN-38 release is obtained at the highest Q value ( Q = 400 μL/min) than is achieved using a conventional bulk preparation method. For all SN-38-PNP formulations, we find a dominant population (by number) of nanosized particles (<50 nm) along with a small number of larger aggregates (>100 nm). As Q increases, the size of aggregates decreases through a minimum and then increases, attributed to a flow-variable competition of shear-induced particle breakup and shear-induced particle coalescence. IC₂₅ and IC₅₀ values of the various SN-38-PNPs against MCF-7 cells show strong flow rate dependencies that mirror trends in particle size. SN-38-PNPs manufactured on-chip at intermediate flow rates show both minimum particle sizes and maximum potencies with a significantly lower IC₂₅ value than the bulk-prepared sample. Compared to conventional bulk methods, microfluidic shear processing in two-phase reactors provides controlled manufacturing routes for optimizing and improving the properties of SN-38 nanomedicines.

RAFT polymerization to form stimuli-responsive polymers

Stimuli-responsive polymers respond to a variety of external stimuli, which include optical, electrical, thermal, mechanical, redox, pH, chemical, environmental and biological signals. This paper is concerned with the process of forming such polymers by RAFT polymerization.

Facile synthesis of poly(vinyl acetate)-b-polystyrene copolymers mediated by an iniferter agent using a single methodology

A novel and convenient method to synthesize diblock copolymers containing both conjugated and non-conjugated monomers, PVAc-b-PS, was established by using a single iniferter methodology.

Star Polymers

Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

Temperature, pH and redox responsive cellulose based hydrogels for protein delivery

Cellulose based hydrogels are important due to their biocompatibility, non-toxicity and natural origin. In this work, a new set of pH, temperature and redox responsive hydrogels were prepared from carboxymethylcellulose (CMC) and poly(N-isopropylacrylamide). Copolymeric (CP) hydrogels were synthesized by copolymerizing N-isopropylacrylamide (NIPA) and methacrylated carboxymethylcellulose, semi-interpenetrating network (SIPN) hydrogels were prepared by polymerizing NIPA in presence of CMC. Two types of cross-linkers were used viz. N,N'-methylenebisacrylamide (BIS) and N,N'-bis(acryloyl)cystamine (CBA), a redox sensitive cross-linker. The structures of the hydrogels were characterized by FTIR and SEM studies. The CP hydrogels were found to be more porous than corresponding SIPNs which resulted in higher swelling for the CP hydrogels. Swelling for both the hydrogels were found to increase with CMC content. While the swelling of SIPN hydrogels showed discontinuous temperature dependency, CP hydrogels showed gradual decrease in water retention values with increase in temperature. CBA cross-linked hydrogels showed higher swelling in comparison to BIS cross-linked hydrogels. Additionally, lysozyme was loaded in the hydrogels and its in vitro release was studied in various pH, temperature and in presence of a reducing agent, glutathione (GSH). The release rate was found to be maximum at lower temperature, lower pH and in presence of GSH.