Approaching Tryptophan-Derived Polynorbornene Fluorescent Chemosensors: Synthesis, Characterization, and Sensing Ability for Biomedical Applications as Biomarkers for Detecting Fe2+ Ions.

We present a novel group of tryptophan (Trp)-based fluorescent polymeric probes synthesized via ring-opening metathesis polymerization (ROMP) of Trp-derived norbornene monomers. These probes, in mono- and disubstituted forms, incorporate amide and ester anchoring groups. The quantity of Trp substituents did not affect fluorescence selectivity but influenced quenching percentage. Poly-diamide-Trp, Poly-monoamide-Trp, Poly-diester-Trp, and Poly-monoester-Trp probes displayed selective detection of Fe2+ and Fe3+ ions with fluorescence on-off characteristics. Poly-diamide-Trp and Poly-monoamide-Trp exhibited a limit of detection (LOD) for Fe2+ and Fe3+ ions of 0.86-11.32 µM, while Poly-diester-Trp and Poly-monoester-Trp showed higher LODs (21.8-108.7 µM). These probes exhibited high selectivity over Fe2+, a crucial metal ion in the body known for its redox properties causing oxidative stress and cell damage. Cell cytotoxicity tests in various cell types confirmed biocompatibility. Additionally, Poly-diamide-Trp displayed excellent cell permeability and iron ion detection in EA.hy926 cells, suggesting potential for bioimaging and clinical applications.

Sugarcane bagasse-derived granular activated carbon hybridized with ash in bio-based alginate/gelatin polymer matrix for methylene blue adsorption.

Sugarcane bagasse (SCB) and sugarcane bagasse ash (SCB-ash) are major agricultural residues from sugar processing industries in Thailand. In this study, SCB-derived activated carbon (SCBAC) with the optimum surface area of 489 m2/g was prepared by steam activation at 900 °C for 1 h. Hybrid granular activated carbons (GACs) were successfully developed by mixing SCBAC with bio-based polymers, alginate and gelatin, at the weight ratio of 3:1 for methylene blue (MB) adsorption. SCB-ash, which was additionally mixed in the GACs, could significantly increase compressive strength of the GACs, but decrease their surface areas and MB adsorption efficiencies. An existence of gelatin up to 30 wt% in the polymer matrix of the GACs showed a slight increase in swelling degree and iodine number, but could not enhance bead strength and MB adsorption efficiency due to its relatively lower bulk density and specific surface area. Maximum MB adsorption capacities of the GACs were found at 290-403 mg/g under this study's experimental condition. MB adsorption efficiencies at above 90 % with no deformation of all of the selected SCB hybrid GACs were finally confirmed after seven consecutive adsorption-desorption cycles using a simple regeneration with ethanol.

Colorimetric ammonia (NH3) sensor based on an alginate-methylcellulose blend hydrogel and the potential opportunity for the development of a minced pork spoilage indicator.

Hydrogels based on alginate and methylcellulose were developed as a colorimetric indicator for monitoring minced pork spoilage. The hydrogel was fabricated by an external gelation method using Ca2+ as the crosslinking agent. The pH-sensitive dye bromothymol blue was incorporated into the hydrogel to act as an indicator. The hydrogel's swelling index increased with an increasing ratio of methylcellulose, suggesting that the water uptake capacity is tunable by the polymer composition. The hydrogel's compression strength is directly proportional to the alginate content. The hydrogel indicator demonstrated a color change from orange to yellow (day 6) upon detecting total volatile basic nitrogen (TVB-N) built up in the package during minced pork storage at 4 °C, and the results showed a positive correlation between the color change, TVB-N and pH change of minced pork. This result demonstrated the potential application of the hydrogel as a spoilage indicator in intelligent packaging.

Alternating ring-opening metathesis copolymerization of amino acid derived norbornene monomers carrying nonprotected carboxy and amino groups based on acid-base interaction.

Amino acid derived norbornene monomers having carboxy (1) and amino groups (2) were synthesized and subjected to ring-opening metathesis copolymerization with various feed ratios using the Grubbs second generation ruthenium catalyst. The M(n)'s of the copolymers ranged from 5300 to 9400 (M(w)/M(n) = 1.40-1.69). The monomer conversion and M(n) of the copolymer were maximized when the monomer feed ratio was 1:1. The monomer unit ratios in the copolymers were almost 1:1 at 10% conversion, irrespective of the feed ratios. The monomer reactivity ratios r(1) and r(2) were estimated to be 0.08 and 0.02, which confirmed that alternating copolymerization occurred. It is considered that alternating copolymerization is brought about by the acid-base interaction between the monomers and/or between the propagating polymer end and the incoming monomer.