Responsive Polymers for Detection and Sensing Applications: Current Status and Future Developments

Abstract

The past two decades have evidenced a tremendous growth in the field of responsive polymers, which can exhibit reversible or irreversible changes in physical properties and/or chemical structures to an external stimulus such as pH, temperature, ionic strength, light irradiation, mechanical forces, electric and magnetic fields, specific analytes, external additives (ions, bioactive molecules, etc.), or a combination of them. Responsive polymers can exist in the form of solutions, gels, self-assembled nanoparticles, (multilayer) films, and bulk solids. The field of responsive polymers has nowadays evolved well beyond the demonstration of novel and interesting properties. Currently, the exploitation of useful and advanced functions, e.g., drug or gene carriers with triggered release properties, catalysis, detection and imaging, environmentally adaptive coatings, and self-healing materials, has emerged to be a more relevant subject. In this Perspective, we focus on recent developments of responsive polymer-based chemo-and biosensors, highlighting this concept with selected literature reports. Such functional polymeric materials show prominent advantages such as tunable detection sensitivity, structural stability, aqueous dispersibility, biocompatibility, processability, and facile integration into detection devices, as compared to their small molecule analogues.

Polymeric nanoparticles for optical sensing

“…In the first mechanism, fluorescence emission is generated by means of specific chemical reactions or recognition phenomena in the presence of the target analyte. For instance, the fluorescence emission of Rhodamine B (RhB) changes according to whether it is in the spirolactam or the acyclic form (Hu et al, 2010;Y. K. Yang, 2005).…”

“…The ring-opening reaction of RhB moieties occurs after the addition of Hg 2+ ions, producing highly intense emission of fluorescence (Hu et al, 2010). In a similar approach a polyethylenglycol (PEG)-based thermo-responsive diblock copolymer containing the coumarin moiety was used for the detection of fluoride (Figure 1) (Jiang et al, 2011).…”

“…Furthermore, the hydrophobic microenvironment created within polymeric NPs can enhance the quantum yield of certain fluorescent reporters (Cui et al, 2013;Hu and Liu, 2010;Shiraishi et al, 2010;Wang et al, 2009). In addition, the presence of reactive functional groups along the polymer backbone allows specific labeling with other molecules as well as allowing the particle surface to be modified for specific applications.…”

Synthesis of spiropyran-containing random copolymer by atom transfer radical polymerization and its complexation with metal ions

“…[1,2] Among various chemical and physical stimuli, [3][4][5][6][7][8][9][10] light as an especially attractive external stimulus has been used in a lot of areas, such as information recording and processing, [11] optical memory and molecular switching devices, [12] and variable transmitting materials. [13] Photochromic compounds have provided a number of interesting molecules due to their inherent transformation to colored species upon exposure to ultraviolet irradiation.…”

Statistical Copolymers Of Benzyl Methacrylate And Diethylaminoethyl Methacrylate: Monomer Reactivity Ratios And Thermal Properties

“…Thermosensitivity was reported for PDEAEMA exhibiting lower critical solution temperature, LCST, meaning that the polymer precipitates from water at elevated temperatures [17,18]. Block copolymers containing PDEAEMA blocks are widely used in the literature as pH -and temperature responsive materials in aqueous solutions, as a consequence of the increase in hydrophobicity upon deprotonation [19,20]. On the other hand benzyl methacrylate (BzMA) is a very interesting monomer, which can be used as a substitute in the methacrylate family of monomers of the very commonly used styrene (St) in copolymerization studies [21].…”