Herein, we present a one-pot microwave-assisted preparative method for water-soluble carbon dots (CDs) in an immiscible system. CDs demonstrated uniform morphology, high quantum yield and excitation-independent fluorescence emission. Moreover, we first reported the observation of thermally activated delayed fluorescence from CDs.
Water is considered as an inert environment for the dispersion of many chemical systems. However, by simply spraying bulk water into microsized droplets, the water microdroplets have been shown to possess a large plethora of unique properties, including the ability to accelerate chemical reactions by several orders of magnitude compared to the same reactions in bulk water, and/or to trigger spontaneous reactions that cannot occur in bulk water. A high electric field (∼109 V/m) at the air–water interface of microdroplets has been postulated to be the probable cause of the unique chemistries. This high field can even oxidize electrons out of hydroxide ions or other closed-shell molecules dissolved in water, forming radicals and electrons. Subsequently, the electrons can trigger further reduction processes. In this Perspective, by showing a large number of such electron-mediated redox reactions, and by studying the kinetics of these reactions, we opine that the redox reactions on sprayed water microdroplets are essentially processes using electrons as the charge carriers. The potential impacts of the redox capability of microdroplets are also discussed in a larger context of synthetic chemistry and atmospheric chemistry.
Abstract Water microdroplets have been demonstrated to exhibit extraordinary chemical behaviors, including the abilities to accelerate chemical reactions by several orders of magnitude and to trigger reactions that cannot occur in bulk water. One of the most striking examples is the spontaneous generation of hydroxyl radical from hydroxide ions. Alcohols and alkoxide ions, being structurally similar to water and hydroxide ions, might exhibit similar behavior on microdroplets. Here, we report the spontaneous generation of alkoxide radicals from alcohols (RCH 2 OH) in aqueous microdroplets through quantum chemical calculations, quantum mechanical/molecular mechanical (QM/MM) molecular dynamics (MD) simulations, ab initio MD simulations, and mass spectrometry. Our results show that an electric field (EF) on the order of 10 −1 V/Å and partial solvation at the air‐water interface jointly promote the dissociation of RCH 2 OH into RCH 2 O − and H 3 O + ions. QM/MM MD simulations indicate that RCH 2 O − can be ionized to produce RCH 2 O⋅ radicals on the microdroplet surface. Furthermore, partial solvation and the EF collaboratively catalyze the isomerization of the RCH 2 O⋅ radical into a more stable tautomer, R⋅CHOH. This study highlights the molecular mechanisms underlying the widespread generation of radicals at the microdroplet surface and provides insights into the importance of fundamental alcohol chemistry in the atmosphere.
Endotoxemia is a life-threatening multiple organ failure disease caused by bacterial endotoxin infection. Unfortunately, current single-target therapy strategies have failed to prevent the progression of endotoxemia. Here, we reported that alanine fullerene redox modulator (AFRM) remodeled the intestinal microenvironment for multiple targets endotoxemia mitigation by suppressing inflammatory macrophages, inhibiting macrophage pyroptosis, and repairing epithelial cell barrier integrity. Specifically, AFRM exhibited broad-spectrum and self-cascade redox regulation properties with superoxide dismutase (SOD)-like enzyme, peroxidase (POD)-like enzyme activity, and hydroxyl radical (•OH) scavenging ability. Guided by proteomics, we demonstrated that AFRM regulated macrophage redox homeostasis and down-regulated LPS/TLR4/NF-κB and MAPK/ERK signaling pathways to suppress inflammatory hyperactivation. Of note, AFRM could attenuate inflammation-induced macrophage pyroptosis via inhibiting the activation of gasdermin D (GSDMD). In addition, our results revealed that AFRM could restore extracellular matrix and cell-tight junction proteins and protect the epithelial cell barrier integrity by regulating extracellular redox homeostasis. Consequently, AFRM inhibited systemic inflammation and potentiated intestinal epithelial barrier damage repair during endotoxemia in mice. Together, our work suggested that fullerene based self-cascade redox modulator has the potential in the management of endotoxemia through synergistically remodeling the inflammation and epithelial barriers in the intestinal microenvironment.
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