3D-Printed Fluorescent Hydrogel Consisting of Conjugated Polymer and Biomacromolecule for Fast and Sensitive Detection of Cr(VI) in Vegetables.

Portable fluorescent film sensors offer a solution to the contamination issue in homogeneous sensor detection systems. However, their special structure leads to low sensitivity and a long response time, resulting in a significant scientific challenge limiting their development and application. In this work, we propose a dual design strategy to prepare highly sensitive film sensors for rapidly detecting Cr2O72-. Specifically, P(Fmoc-Osu)-SA hydrogel films were developed by integrating the biological macromolecule sodium alginate (SA) with the conjugated polymer poly(N-(9-Fluorenylmethoxycarbonyloxy)succinimide) (P(Fmoc-Osu)), using both mold and inkjet 3D printing methods. The "molecular wire effect" of the sensing unit P(Fmoc-Osu) and the water channel within the film substrate are responsible for the improved sensitivity and the reduced response time of this thin film sensor. P(Fmoc-Osu)-SA hydrogel films prepared by these two methods can rapidly detect Cr2O72- with limits of detection of 1.18 and 0.078 nM, respectively. Considering that 3D-printed hydrogel films can be tailored to different shapes according to detection needs, the P(Fmoc-Osu)-SA hydrogel films produced from this method were effectively applied in vegetable samples. This study provides an innovative and effective strategy for the development of biocompatible hydrogel sensors that offer the potential for determining trace amounts of Cr2O72- in agriculture.

Conjugated Polymer-Based Hydrogel Film for a Fast and Sensitive Detection of Fe(â ¢) in Vegetables.

Fluorescent film sensors are ideal for the real-time outdoor detection of heavy metal ions of Fe3+, but they are limited because of their low sensitivity and long response time due to their special structure. In this work, we constructed a fluorescent hydrogel for the specific detection of Fe3+, utilizing poly(9-fluorenecarboxylic acid) (PFCA) as the sensing moiety and sodium alginate (SA) as the cross-linking substrate, which exhibited a rapid and selective recognition of Fe3+ among a panel of 16 anions and 21 cations. It can sense Fe3+ at 0.1 nM immediately owing to the porous network structure of the PFCA-SA film that provided enhanced ion transport channels and active sites, and the "molecular line effect" of polymer PFCA. Moreover, we successfully applied this platform to detect Fe3+ in four different vegetable samples. This work provides an innovative and effective strategy for fabricating green and sustainable fluorescent sensors.

Measurement of Personal Experienced Temperature Variations in Rural Households Using Wearable Monitors: A Pilot Study.

The time-varying data of air temperatures experienced by people in their daily lives is an important basis for studying human thermal sensation, adaptation, comfort, and health. It is also very important for designing targeted strategies to help people reduce uncomfortable experience. In this study, a small (98 mm × 49 mm × 25 mm), lightweight (~100 g), and portable temperature logger with a wide measurement range (-40 to 100 °C) and appropriate accuracy (±0.3 °C precision) was combined with a phone holder that was adapted as an armband sleeve to constitute a wearable monitor. Fourteen monitors were worn by 14 residents in 6 different households in rural Beijing, China, to monitor their personal thermal environment. In the context of having very similar living habits in winter and coping strategies for thermal discomfort, the temperatures that 14 residents experienced exhibited wide ranges and large variations during the two-day test period. The highest and lowest temperatures experienced by residents reached 30.6 and -16.6 °C, respectively. This paper provided new data and evidences about various temperatures experienced by residents, even though they were from the same family and lived together for decades. In terms of methodology, as an exploration, the present study indicated that using personal wearable monitors is a viable method to capture the real experienced thermal environment, which extended the method for collecting data regarding complex experiences in different environments to aid the study of human responses to the real-world thermal environment.