Molecular Design, Synthetic Strategies, and Applications of Cationic Polythiophenes.

This review delves into the synthesis of cationic-functionalized oligothiophenes and polythiophenes, their properties, and their diverse applications from the year 2002 to 2019. Pristine polythiophene chains are hydrophobic and are not easily converted into a form that is useful for broad applications or for device fabrications. Functional modification of the polymer side chain especially with cationic pendant groups imparts favorable properties to the system, such as solubility in aqueous medium and affinity with anions and negatively charged species, alongside the extensive π conjugation that provides unique optoelectronic characteristics. This review provides a detailed account of the design and the different synthetic strategies to access cationic polythiophenes (CPTs) via chemical oxidation using iron(III) chloride (FeCl3), via metal catalyzed and initiated polymerization, and via postpolymerization functionalization approaches. CPTs have been traditionally used in sensing and as a component in optoelectronic devices; the utility of these systems has been extended to biomedical applications, such as nonviral gene delivery, cell targeting and imaging, anticancer, antifungal, and bactericidal actions, and biofilm formation, and to use as a molecular probe. A summary and outlook are also presented, discussing the remaining challenges and the future direction for this field.

Glycolipids that elicit IFN-γ-biased responses from natural killer T cells.

Natural killer T (NKT) cells recognize glycolipids presented by CD1d. The first antigen described, α-galactosyl ceramide (αGalCer), is a potential anticancer agent whose activity depends upon IFN-γ secretion. We report two analogs of αGalCer based on a naturally occurring glycosphingolipid, plakoside A. These compounds induce enhanced IFN-γ that correlates with detergent-resistant binding to CD1d and an increased stability of the lipid-CD1d complexes on antigen-presenting cells. Structural analysis on one of the analogs indicates that it is more deeply bound inside the CD1d groove, suggesting tighter lipid-CD1d interactions. To our knowledge, this is the first example in which structural information provides an explanation for the increased lipid-CD1d stability, likely responsible for the Th1 bias. We provide insights into the mechanism of IFN-γ-inducing compounds, and because our compounds activate human NKT cells, they could have therapeutic utility.

Overcoming multidrug resistance of breast cancer cells by the micellar doxorubicin nanoparticles of mPEG-PCL-graft-cellulose.

The amphiphilic block copolymer methoxy-poly(ethylene glycol)-poly(epsilon-caprolactone) (mPEG-PCL) was grafted to 2-hydroxyethyl cellulose (HEC) to produce nano-sized micellar nanoparticles. The nanoparticles were loaded with anti-tumor drug, doxorubicin (DOX) and the size of the DOX-loaded nanoparticles were determined by dynamic light scattering (DLS) in aqueous solution to be from 197.4 to 230 nm. The nanoparticles subjected to co-culture with macrophage cells showed that these nanoparticles used as drug carrier are not recognized as foreign bodies. Overexpression of P-glycoprotein (P-gp) is an important factor in the development of multidrug resistance (MDR) in many cancer cells. In this study, Western blot and Rhodamine 123 were used to monitor the relative P-glycoprotein expression in human breast cancer cell lines MCF-7/WT and MCF-7/ADR. The endocytosis of the DOX-loaded nanoparticles by breast cancer cells is more efficient observed under a confocal laser scanning microscopy (CLSM) and a flow cytometry in MCF7/ADR cells, compared to the diffusion of the free drug into the cytoplasm of cells. Based on these findings, we concluded that the nanoparticles made from mPEG-PCL-g-cellulose were effective in overcoming P-gp efflux in MDR breast cancer cells.