Energy efficiency has been a hot research topic for many years and many routing algorithms have been proposed to improve energy efficiency and to prolong lifetime for wireless sensor networks (WSNs). Since nodes close to the sink usually need to consume more energy to forward data of its neighbours to sink, they will exhaust energy more quickly. These nodes are called hot spot nodes and we call this phenomenon hot spot problem. In this paper, an Enhanced Power Efficient Gathering in Sensor Information Systems (EPEGASIS) algorithm is proposed to alleviate the hot spots problem from four aspects. Firstly, optimal communication distance is determined to reduce the energy consumption during transmission. Then threshold value is set to protect the dying nodes and mobile sink technology is used to balance the energy consumption among nodes. Next, the node can adjust its communication range according to its distance to the sink node. Finally, extensive experiments have been performed to show that our proposed EPEGASIS performs better in terms of lifetime, energy consumption, and network latency.
Reactive oxygen species (ROS)‐based cancer therapy, such as photodynamic therapy (PDT), is subject to the hypoxia and overexpressed glutathione (GSH) found in the tumor microenvironment (TME). Herein, a novel strategy is reported to continuously and simultaneously regulate tumor hypoxia and reducibility in order to achieve the desired therapeutic effect. To accomplish this, a biocompatible nanoplatform (MnFe2O4@metal–organic framework (MOF)) is developed by integrating a coating of porphyrin‐based MOF as the photosensitizer and manganese ferrite nanoparticle (MnFe2O4) as the nanoenzyme. The synthetic MnFe2O4@MOF nanoplatform exhibits both catalase‐like and glutathione peroxidase‐like activities. Once internalized in the tumor, the nanoplatform can continuously catalyze H2O2 to produce O2 to overcome the tumor hypoxia by cyclic Fenton reaction. Meanwhile, combined with the Fenton reaction, MnFe2O4@MOF is able to persistently consume GSH in the presence of H2O2, which decreases the depletion of ROS upon laser irradiation during PDT and achieves better therapeutic efficacy in vitro and in vivo. Moreover, the nanoplatform integrates a treatment modality with magnetic resonance imaging, along with persistent regulation of TME, to promote more precise and effective treatment for future clinical application.
In chemodynamic therapy (CDT), real-time monitoring of
reactive
oxygen species (ROS) production is critical to reducing the nonspecific
damage during CDT and feasibly evaluating the therapeutic response.
However, CDT agents that can emit ROS-related signals are rare. Herein,
we synthesize a semiconducting polymer nanoplatform (SPN) that can
not only produce highly toxic ROS to kill cancer cells but also emit
ROS-correlated chemiluminescent signals. Notably, the efficacy of
both chemiluminescence and CDT can be significantly enhanced by hemin
doping (∼10-fold enhancement for luminescent intensity). Such
ROS-dependent chemiluminescence of SPN allows ROS generation within
a tumor to be optically monitored during the CDT process. Importantly,
SPN establishes an excellent correlation of chemiluminescence intensities
with cancer inhibition rates in vitro and in vivo. Thus, our nanoplatform
represents the first intelligent strategy that enables chemiluminescence-imaging-monitored
CDT, which holds potential in assessing therapeutic responsivity and
predicting treatment outcomes in early stages.
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