Harnessing antimicrobial peptide-coupled photosensitizer to combat drug-resistant biofilm infections through enhanced photodynamic therapy

Bacterial biofilm-associated infection was one of the most serious threats to human health. However, effective drugs for drug-resistance bacteria or biofilms remain rarely reported. Here, we propose an innovative strategy to develop a multifunctional antimicrobial agent with broad-spectrum antibacterial activity by coupling photosensitizers (PSs) with antimicrobial peptides (AMPs). This strategy capitalizes on the ability of PSs to generate reactive oxygen species (ROS) and the membrane-targeting property of AMPs (KRWWKWIRW, a peptide screened by an artificial neural network), synergistically enhancing the antimicrobial activity. In addition, unlike conventional aggregation-caused quenching (ACQ) photosensitizers, aggregation-induced emission (AIE) PSs show stronger fluorescence emission in the aggregated state to help visualize the antibacterial mechanism. In vitro antibacterial experiments demonstrated the excellent killing effects of the developed agent against both Gram-positive (G^(+)) and Gram-negative (G^(–)) bacteria. The bacterial-aggregations induced ability enhanced the photoactivatable antibacterial activity against G^(–) bacteria. Notably, it exhibited a significant effect on destroying MRSA biofilms. Moreover, it also showed remarkable efficacy in treating wound infections in mice in vivo. This multifunctional antimicrobial agent holds significant potential in addressing the challenges posed by bacterial biofilm-associated infections and drug-resistant bacteria.

Ethanol extract of Cyathulae Radix inhibits osteoclast differentiation and bone loss

Cyathulae Radix,a traditional Chinese medicine and a common vegetable,boasts a history spanning millennia.It enhances bone density,boosts metabolism,and effectively alleviates osteoporosis-induced pain.Despite its historical use,the molecular mechanisms behind Cyathulae Radix’s impact on osteoporosis remain unexplored.In this study,we investigated the effects and mechanisms of Cyathulae Radix ethanol extract(CEE)in inhibiting osteoporosis and osteoclastogenesis.Eight-week-old female mice underwent ovariectomy and were treated with CEE for eight weeks.Micro-computed tomography(micro-CT)assessed histomorphometric parameters,bone tissue staining observed distal femur histomorphology,and three-point bending tests evaluated tibia mechanical properties.Enzyme-linked immunosorbent assay(ELISA)measured serum estradiol(E2),receptor activator for nuclear factor B ligand(RANKL),and osteoprotegerin(OPG)levels.Osteoclastogenesis-related markers were analyzed via Western blotting(WB)and quantitative real-time polymerase chain reaction(qRT-PCR).Additionally,CEE effects on RANKL-induced osteoclast formation and bone resorption were investigated in vitro using tartrate-resistant acid phosphatase(TRAP)staining,qRT-PCR,and WB assay.Compared with the ovariectomy(OVX)group,CEE treatment enhanced trabecular bone density,maximal load-bearing capacity,and various histomorphometric parameters.Serum E2 and OPG levels significantly increased,while Receptor activator of nuclear factor-κB(RANK)decreased in the CEE group.CEE downregulated matrix metallopeptidase 9(MMP-9),Cathepsin K(CTSK),and TRAP gene and protein expression.In bone marrow macrophages(BMMs),CEE reduced mature osteoclasts,bone resorption pit areas,and MMP-9,CTSK,and TRAP expression during osteoclast differentiation.Compared with DMSO treatment,CEE markedly inhibited RANK,TNF receptor associated factor 6(TRAF6),Proto-oncogene c-Fos(c-Fos),Nuclear factor of activated T-cells cytoplasmic 1(NFATc1)expressions,and Extracellular regulated protein kinases(ERK),c-Jun N-terminal kinase(JNK),NF-kappa B-p65(p65)phosphorylation in osteoclasts.In conclusion,CEE significantly inhibits OVX-induced osteoporosis and RANKL-induced osteoclastogenesis,potentially through modulating the Estrogen Receptor(ER)/RANK/NFATc1 signaling pathway.

The exquisite integration of ESIPT, PET and AIE for constructing fluorescent probe for Hg(II) detection and poisoning

Excessive mercury ions(Hg^(2+)) in the environment can accumulate in human body along with the food chain to cause serious physiological reactions.The fluorescence probes were considered as convenient tool with great potential for Hg^(2+) detection.Most existing probes suffer from aggregation-induced quenching(ACQ) effects and insufficient sensitivity.Herein,a novel type of fluorophore was developed by combining the aggregation-induced emission(AIE) and excited state intramolecular proton transfer(ESIPT) characteristics.Subsequently,a phenyl thioformate group with photoinduced electron transfer(PET)effect was connected to give an efficient "turn-on" probe(HTM),which exhibited good selectivity toward Hg^(2+),short response time(30 min),coupled with extremely low detection limit(LOD=1.68 nmol/L).In addition,HTM was used successfully in real samples,cells and drug evaluation,underlying the superiority of HTM to detect Hg^(2+) in practical applications.

Monitoring intracellular pH fluctuation with an excited-state intramolecular proton transfer-based ratiometric fluorescent sensor

Intracellular pH is a key parameter related to various biological and pathological processes.In this study,a ratiometric pH fluorescent sensor ABTT was developed harnessing the amino-type excited-state intramolecular proton transfer(ESIPT) process.Relying on whether the ESIPT proceeds normally or not,ABTT exhibited the yellow fluorescence in acidic media,or cyan fluorescence in basic condition.According to the variation,ABTT behaved as a promising sensor which possessed fast and reversible response to pH change without interference from the biological substances,and exported a steady ratiometric signal(I_(478)/I_(546)).Moreover,due to the ESIPT effect,large Stokes shift and high quantum yield were also exhibited in ABTT.Furthermore,ABTT was applied for monitoring the pH changes in living cells and visualizing the pH fluctuations under oxidative stress successfully.These results elucidated great potential of ABTT in understanding pH-dependent physiological and pathological processes.