Hydrogen Sulfide Induced Unique Twisted-Rod Assemblies from Norbornene-Based Polymer in Aqueous Environment as Gasotransmitter Regulators

Hydrogen sulfide, being a poisonous pollutant, (H2S) is known for its pungent smell. Although it is having significant role in the biological and physiological processes as a potential biomarker in the present day. The over-expression of H2S leads to several biological disorders and diseases, therefore, monitoring the level of H2S in the biological pH is important. Optical sensors to detect hydrogen sulfide have gained popularity due to their cost-effectiveness, portability, fast response, etc. Here, we are designing a norbornene-based polymeric bio-sensor for detecting hydrogen sulfide in physiological pH. Hydrophilic and hydrophobic monomers are strategically crafted to permeate polymeric sensors with water solubility and the ability to detect hydrogen sulfide, respectively. These monomers are polymerized by ring-opening metathesis polymerization (ROMP). The probe is characterized by nuclear magnetic resonance (NMR) spectroscopy, fluorescence, and UV-visible absorbance spectra. The polymeric sensor can selectively detect hydrogen sulfide with high sensitivity by turn-on fluorescence responses. Moreover, this probe efficiently conducts the morphological changes associated with sensing phenomena. The collapsed vesicles are nicely converted into twisted rods. One dimentional structures (such as twisted rods, etc.) are becoming very interesting as they have fascinating structural and functional properties. Having application in biomedical fields such as targeted drug delivery, imaging, and scaffolds for tissue engineering, it also can exhibits improved mechanical strength, flexibility, unique optical properties, increased surface area, etc. This probe is biocompatible and has the scopes for bio-imaging. Therefore, this water-soluble polymeric probe can open new bio-medical applications for detecting analytes.

Double hydrophilic copolymers - synthetic approaches, architectural variety, and current application fields

Solubility and functionality of polymeric materials are essential properties determining their role in any application. In that regard, double hydrophilic copolymers (DHC) are typically constructed from two chemically dissimilar but water-soluble building blocks. During the past decades, these materials have been intensely developed and utilised as, e.g., matrices for the design of multifunctional hybrid materials, in drug carriers and gene delivery, as nanoreactors, or as sensors. This is predominantly due to almost unlimited possibilities to precisely tune DHC composition and topology, their solution behavior, e.g., stimuli-response, and potential interactions with small molecules, ions and (nanoparticle) surfaces. In this contribution we want to highlight that this class of polymers has experienced tremendous progress regarding synthesis, architectural variety, and the possibility to combine response to different stimuli within one material. Especially the implementation of DHCs as versatile building blocks in hybrid materials expanded the range of water-based applications during the last two decades, which now includes also photocatalysis, sensing, and 3D inkjet printing of hydrogels, definitely going beyond already well-established utilisation in biomedicine or as templates.

A Reusable Polymeric Film for the Alternating Colorimetric Detection of a Nerve Agent Mimic and Ammonia Vapor with Sub-Parts-per-Million Sensitivity

Thin polymeric films were developed for the vapor-phase sequential colorimetric detection of a nerve agent mimic and ammonia with high sensitivity. N-(4-Benzoylphenyl)acrylamide (BPAm), N,N-dimethylacrylamide (DMA), and (E)-2-(methyl(4-(pyridine-4yldiazenyl)phenyl)amino)ethyl acrylate (MPDEA, M1) were copolymerized via free radical polymerization (FRP) to yield p(BPAm-co-DMA-co-MPDEA), hereafter referred to as P1. P1 exhibits selective sensing properties toward diethyl chlorophosphate (DCP), a nerve agent mimic, in pure aqueous media. Upon the addition of DCP, the pyridine groups of P1 were quaternized with DCP, accompanied by a color change from yellow to pink due to the enhancement of the intramolecular charge transfer (ICT) effect. In situ generated quaternized P1, hereafter referred to as P2, after DCP sensing was used to selectively detect ammonia via dequaternization in an aqueous medium. Ammonia detection was indicated by a color change in the solution from pink back to yellow. A surface-immobilized P1 film was prepared and employed for the vapor-phase detection of DCP, demonstrating that an amount of as low as 2 ppm was detectable. Ammonia vapor was also successfully detected by the P2 film via the ammonia-triggered removal of the quaternized phosphates. Alternating exposure of the film to DCP and ammonia resulted in the corresponding color changes, thereby demonstrating the reversibility of the system. The reusability of the polymeric film for detecting DCP and ammonia in the vapor phase was confirmed by performing four sequential colorimetric detection cycles.

Thermoresponsive properties of poly(N-isopropyl,N-methylacrylamide) and its statistical and block copolymers with poly(N,N-dimethylacrylamide) prepared by B(C6F5)3-catalyzed group transfer polymerization

B(C₆F₅)₃-catalyzed GTP synthesis of poly(N-isopropyl,N-methylacrylamide) as a new thermoresponsive material.