Novel multi-responsive P2VP-block-PNIPAAm block copolymers via nitroxide-mediated radical polymerization

Amphiphilic Block Copolymers: Their Structures, and Self-Assembly to Polymeric Micelles and Polymersomes as Drug Delivery Vehicles

Self-assembly of amphiphilic block copolymers display a multiplicity of nanoscale periodic patterns proposed as a dominant tool for the 'bottom-up' fabrication of nanomaterials with different levels of ordering. The present review article focuses on the recent updates to the self-association of amphiphilic block copolymers in aqueous media into varied core-shell morphologies. We briefly describe the block copolymers, their types, microdomain formation in bulk and micellization in selective solvents. We also discuss the characteristic features of block copolymers nanoaggregates viz., polymer micelles (PMs) and polymersomes. Amphiphilic block copolymers (with a variety of hydrophobic blocks and hydrophilic blocks; often polyethylene oxide) self-assemble in water to micelles/niosomes similar to conventional nonionic surfactants with high drug loading capacity. Double hydrophilic block copolymers (DHBCs) made of neutral block-neutral block or neutral block-charged block can transform one block to become hydrophobic under the influence of a stimulus (physical/chemical/biological), and thus induced amphiphilicity and display self-assembly are discussed. Different kinds of polymer micelles (viz. shell and core-cross-linked, core-shell-corona, schizophrenic, crew cut, Janus) are presented in detail. Updates on polymerization-induced self-assembly (PISA) and crystallization-driven self-assembly (CDSA) are also provided. Polyion complexes (PICs) and polyion complex micelles (PICMs) are discussed. Applications of these block copolymeric micelles and polymersomes as nanocarriers in drug delivery systems are described.

Poly(2-vinylpyridine) as a reference compound for mass calibration in positive-ion matrix-assisted laser desorption/ionization-mass spectrometry on different instrumental platforms

Butyl-terminated poly(2-vinylpyridine) (P2VP), C₄H₉(C₇H₇N)_nH, is evaluated for use as an external and internal mass calibrant in positive-ion matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). P2VP oligomers covering the m/z 450-4500 range are employed to calibrate a time-of-flight (TOF) mass spectrometer in linear and reflector mode, an ion mobility-quadrupole-time-of-flight (IM-Q-TOF) mass spectrometer, and a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The proton affinity of P2VPs introduced by the numerous pyridyl groups leads to the almost exclusive formation of [M + H]⁺ ions with common acidic matrices like α-cyano-4-hydroxycinnamic acid (CHCA) and 2,5-dihydroxybenzoic acid (DHB) as well as with the non-acidic and aprotic matrices 1,8-dihydroxy-10H-anthracen-9-on (dithranol) and 2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene]malonitrile (DCTB). This prevalence of [M + H]⁺ ions evenly spaced at Δ(m/z) = 105.0578 renders butyl-terminated P2VP oligomers as convenient mass calibrants. The mass accuracies achieved across various m/z ranges with different mass analyzers and modes of operation are evaluated by using established standard compounds. Results as obtained by internal or external calibration are presented. Further, the compilation of mass reference lists tailored to suit the respective analyzer modes is discussed and those reference files are provided.

pH-Responsive polymers

This review summarizes pH-responsive monomers, polymers and their derivative nano- and micro-structures including micelles, cross-linked micelles, microgels and hydrogels.

A RAFT copolymerization of NIPAM and HPMA and evaluation of thermo-responsive properties of poly(NIPAM-co-HPMA)

66 (co)polymers of NIPAM and HPMA with varying MW, composition, and end functionality were synthesized by RAFT polymerization and their thermo-responsive properties were systematically evaluated.

Synthetic polymer as an adjuvant in collagen-induced arthritis

Collagen-induced arthritis (CIA), the classical animal model for experimental arthritis, resembles human rheumatoid arthritis in several aspects. However, the most widely used method of inducing CIA utilizes Freund's adjuvants, which can skew the elicited immune responses and also pose toxicity problems. This unit describes a new method of inducing CIA using a well defined stimuli-responsive synthetic polymer, poly-N-isopropylacrylamide-based adjuvant, mixed with the joint cartilage protein collagen type II (CII). PNiPAAm as an adjuvant is biodegradable and biocompatible, and does not skew immune responses. Thus, it is helpful in the development of arthritis models for studying antigen and tissue -specific autoimmune responses in an unbiased manner. This model is valuable for analyzing disease pathways, positional identification of genes regulating arthritis, validation of existing therapies, and exploring new therapeutic targets. Furthermore, this newly developed PNiPAAm adjuvant allows investigation of disease induction using specific autoantigens in several autoimmune diseases independently of toll-like receptors, as well as optimization of vaccine delivery systems for infectious diseases.