Mycobacteriaceae Mineralizes Micropolyethylene in Riverine Ecosystems.

Microplastic (MP) contamination is a serious global environmental problem. Plastic contamination has attracted extensive attention during the past decades. While physiochemical weathering may influence the properties of MPs, biodegradation by microorganisms could ultimately mineralize plastics into CO2. Compared to the well-studied marine ecosystems, the MP biodegradation process in riverine ecosystems, however, is less understood. The current study focuses on the MP biodegradation in one of the world's most plastic contaminated rivers, Pearl River, using micropolyethylene (mPE) as a model substrate. Mineralization of 13C-labeled mPE into 13CO2 provided direct evidence of mPE biodegradation by indigenous microorganisms. Several Actinobacteriota genera were identified as putative mPE degraders. Furthermore, two Mycobacteriaceae isolates related to the putative mPE degraders, Mycobacterium sp. mPE3 and Nocardia sp. mPE12, were retrieved, and their ability to mineralize 13C-mPE into 13CO2 was confirmed. Pangenomic analysis reveals that the genes related to the proposed mPE biodegradation pathway are shared by members of Mycobacteriaceae. While both Mycobacterium and Nocardia are known for their pathogenicity, these populations on the plastisphere in this study were likely nonpathogenic as they lacked virulence factors. The current study provided direct evidence for MP mineralization by indigenous biodegraders and predicted their biodegradation pathway, which may be harnessed to improve bioremediation of MPs in urban rivers.

An ingenious cellulose membrane sensor design strategy for colorimetric detection of Ag+/Hg2+ based on redox reaction.

This paper describes an ingenious cellulose membrane sensor design strategy for colorimetric detection of Ag+/Hg2+ based on redox reaction. The colorless 3,3',5,5'-tetramethylbenzidine (TMB) can be oxidized to blue oxidized TMB (oxTMB) when exposed to Ag+/Hg2+ that with strong oxidizing properties. Based on this phenomenon, TMB can be design as a colorimetric probe for Ag+/Hg2+, and the reaction mechanism and sensing performance of TMB as Ag+/Hg2+ were explored. In addition, the TMB probe-immobilized cellulose membranes (TMB@CMs) were developed by combining TMB with high-purity cellulose membranes (CMs) carrier with porous and polyhydroxy structures. As a platform for probe immobilization, TMB@CMs can effectively improve colorimetric sensing response and stability of TMB. The colorimetric mechanism of TMB@CMs was investigated including in situ oxidation of TMB and immediate immobilization of oxTMB. The experimental results showed that the visual detection limit (VLOD) of Ag+/Hg2+ was 10 µM when TMB was used as colorimetric probe, while the VLOD of the TMB@CMs was 1 µM. In addition, TMB@CMs had good reusability and stability. Through the analysis of SEM, EDS and XPS results, the mechanism of TMB colorimetric detection of Ag+/Hg2+ was that blue oxTMB and Ag/Hg elementals were generated by redox reaction between them. This study not only verified the feasibility of TMB as an Ag+/Hg2+ colorimetric probe, but also designed a probe-immobilized cellulose membrane model with convenient operation, uniform color development and stable color, which effectively improved the colorimetric sensing response and stability.

Near-Infrared Conjugated Polymers Containing Thermally Activated Delayed Fluorescence Units Enable Enhanced Photothermal Therapy.

Photothermal therapy (PTT) using near-infrared (NIR) conjugated polymers as photosensitizers has exhibited enormous potential for tumor treatment. However, most NIR conjugated polymers have poor therapeutic efficacy due to their faint absorbance in the NIR region and low photothermal conversion efficiency (PCE). Herein, a valuable strategy for designing NIR polymeric photosensitizer PEKBs with an enhanced PCE accompanied by strong NIR absorbance is proposed by means of inserting TPA-AQ as a thermally activated delayed fluorescence unit into a polymeric backbone. In these PEKBs, PEKB-244 with the appropriate molar content of the TPA-AQ unit displays the strongest NIR absorbance and the highest PCE of 64.5%. Theoretical calculation results demonstrate that the TPA-AQ unit in the polymeric backbone can modulate the intramolecular charge transfer effects and the excited energy decay routes for generating higher heat. The prepared nanoparticles (PEKB-244 NPs) exhibit remarkable photothermal conversion capacities and great biocompatibility in aqueous solutions. Moreover, PEKB-244 NPs also show outstanding photothermal stability, displaying negligible changes in the absorbance within 808 nm irradiation of 1 h (800 mW cm-2). Both in vitro and in vivo experimental results further indicate that PEKB-244 NPs can substantially kill cancer cells under NIR laser irradiation. We anticipate that this novel molecular design strategy can be employed to develop excellent NIR photosensitizers for cancer photothermal therapy.

Nanomedicine: An Emerging Novel Therapeutic Strategy for Hemorrhagic Stroke.

Hemorrhagic stroke is one of the most devastating diseases worldwide due to a high rate of disability and mortality with few effective treatments. Recent advances in nanomedicines to promote hemostasis, drug delivery, neuroprotection, and nerve regeneration may provide insight into hemorrhagic stroke treatment. In this review, we first view the pathophysiology and conventional therapeutics of hemorrhagic stroke. Second, we comprehensively summarize the current nanomedicines applied in hemorrhagic stroke, including inorganic nanomaterials, polymer-based nanomaterials, lipid-based nanomaterials, self-assembling peptide-based hydrogel, exosomes, and gel systems. Finally, the challenges, opportunities, and future perspectives of nanomedicines for hemorrhagic stroke are discussed. Thus, this review promotes greater exploration of effective therapies for hemorrhagic stroke with nanomedicines.

Hypercrosslinked strong cation-exchange polymers for selective extraction of serum purine metabolites associated with gout.

In this study, hypercrosslinked strong cation-exchange polymer resins (HXLPP-SCX) were synthesized and employed as selective sorbents for the solid-phase extraction (SPE) of basic purine metabolites associated with gout. The HXLPP-SCX material was prepared based on hypercrosslinking reactions and sulfonated with concentrated H2SO4. This synthetic procedure is facile and efficient without using highly toxic reagent. The resulting resins were characterized in the form of monodisperse microspheres (mean diameters of 3‒5µm) with narrow pore size (2.1nm) and relatively high specific surface areas (801m(2)/g). The polymers also possess high ion-exchange capacity (IEC, 2.22mmol/g) and good adsorption and selectivity performances for basic compounds. The resins used as SPE sorbents permit the selective enrichment of three pivotal purine metabolites (hypoxanthine, xanthine and inosine) in human serum followed by HPLC analysis. Method validation including linearity range, sensitivity, accuracy and reproducibility were evaluated. This method was exemplarily applied in the analysis of serum purines in gout patients and healthy controls. The present results demonstrate a promising potential of this HXLPP-SCX material for the clinical sample pretreatment.