Caprolactone-Based Biodegradable Polymer for Selective, Sensitive Detection and Removal of Cu2+ Ions from Water.

Even though heavy and transition metals originated in the earth's crust, the significant human exposure and environmental pollution consequences of anthropogenic activities include industrial production and waste, mining and smelting operations, and agricultural and domestic usage of metals. Because of their nonbiodegradable nature, heavy metal ions such as Cu2+ accumulate very quickly in plants and edible animals, ultimately ending up in the human food cycle. Therefore, to nullify the detrimental effects of Cu2+ ions for the sake of the environment and living organisms, we are motivated to design a sensor molecule that can not only detect Cu2+ ions but also remove them selectively from the water medium. To detect the Cu2+ ions, we synthesized a monomer (NCu) and its biodegradable caprolactone-based polymer (PNCu). It was observed that both NCu and PNCu showed higher selectivity toward Cu2+ ions by changing the color from colorless to yellow, with a limit of detection value of 29 nM and 0.3 µM. Furthermore, removing the Cu2+ ions from the water solution was also accomplished by introducing the hydrophobicity of the polymer (PNCu) through the ring-opening polymerization process. Due to increased hydrophobicity, the polymer produced a yellow color precipitate upon adding Cu2+ ions to the solution; thus, removal of the metal ion is possible using our designed polymer and its detection ability. We checked the removal efficiency of our polymer by using UV-vis spectroscopy and EDX analysis, which indicated that almost all of the copper is removed by our polymer. Therefore, to our knowledge, this is the first biodegradable caprolactone-based polymer for colorimetric turn-on detection and separation of the Cu2+ ions from the water.

Unique Reaction-Based Polynorbornene Sensing Probes for Ultrasensitive Detection of Hydrazine in Both Environmental and Biological Systems.

Hydrazine-mediated formation of 1,4-phthalazinedione analogues from phthalimide-like components has been utilized to formulate fluorescent probe NorTh. A turn-on fluorescent process has been evaluated to detect hydrazine in a highly selective manner by a small molecular probe NorTh and its homopolymer Poly-NorTh. Both these probes have been evaluated as excellent candidates for nanomolar level detection of hydrazine with a time frame of <15 min, which is rapid in terms of real application. Due to the reaction-based detection process, we have achieved high selectivity for our probes toward the identification of hydrazine in the presence of metal ions, anions, amino acids, and various amines. Limit of detection values are 16 and 35 nM for NorTh and Poly-NorTh, respectively, which are well below the permissible limit given by WHO and EPA. Poly-NorTh has been utilized to detect hydrazine in environmental water samples, soil samples, and biological samples to establish the applicability of our probes in real-field scenarios. We introduce an easy-to-synthesize, cheap, and small molecular probe and its polymer for ultrafast, highly selective, and sensitive detection of hydrazine in all possible mediums to counter the hydrazine toxicity through fluorescence turn-on signal output.

Coordinately Tethered Iron(III) Fluorescent Nanotheranostic Polymer Ascertaining Cancer Cell Mitochondria Destined Potential Chemotherapy and T1-Weighted MRI Competency.

Magnetic resonance imaging-aided real-time diagnosis along with enhanced chemotherapeutic efficacy using a sequential receptor and mitochondria dual-targeting polymer theranostic has become a promising strategy for the effective and precise treatment of cancer. Toward the accomplishment of this goal, chlorambucil (chemotherapeutic agent), biotin (receptor targeting agent), a triphenylphosphonium segment (mitochondriotropic agent), and an iron rhodamine complex (integrated fluorescence-MR imaging agent) were tethered under a single polymer. Owing to the polymer's (RD CH PG BN TP Fe) amphiphilic character, it spontaneously self-assembled into nanospheres, which exhibited a remarkable effect on the relaxation of the water proton. Further, the qualitative estimation of the change in intensity for the water-proton signal reflected its potential as a T1 contrast theranostic polymer. The mitochondria targeting competency of positively charged nanospheres was displayed using fluorescence microscopy in human cervical, HeLa, and breast, MCF-7, carcinoma cell lines. Furthermore, cytotoxicity experiments demonstrated the enhanced anticancer efficacy in both cancer cell lines. Therefore, effective and precise chemotherapy through sequential receptor-mitochondria targeting and integrated fluorescence-MR imaging would have attractive potential for decisive dose-determination by constantly monitoring the subject area of interest.

Unusual red-orange emission from rhodamine-derived polynorbornene for selective binding to Fe3+ ions in an aqueous environment.

Norbornene-based rhodamine derivative (NR) was observed as an "off-on" probe for Fe3+ ions both colorimetrically and fluorimetrically in an aqueous environment. NR and its homopolymer (PNR) were capable of detecting Fe3+ ions with high selectivity and sensitivity in an aqueous environment. For NR and PNR the limit of detection (LOD) towards Fe3+ ions was found to be 49 nM and 19 nM, respectively, making these materials highly efficient. Most interestingly, PNR has more efficacy towards the detection of Fe3+ ions than NR, which is expected due to the favorable side-chain interaction in the presence of multiple sensing motifs between the polymer chains. The sensing behavior was thoroughly studied via spectroscopic techniques. We hypothesized that the Fe3+ ion was expected to induce the spirolactam ring-opening of the rhodamine unit due to its Lewis acid nature and preferable interactions with the N and O atoms present in NR as well as PNR.