Cotton is a widely cultivated cash crop and represents one of the most significant raw materials for textiles on a global scale. The rapid development of the cotton industry has resulted in the production of substantial amounts of cotton husks, which are frequently underutilized or discarded. This study utilizes agricultural waste, specifically cotton shells, as a precursor for biochar, which is subsequently carbonized and nitrogen-doped with ruthenium oxide to synthesize an innovative composite material known as RuO₂-NC. An electrochemical sensor was developed using this composite material to detect heavy metals, particularly lead and copper ions. The results demonstrate that the electrochemical sensor can accurately quantify concentrations of lead and copper ions across a wide linear range, exhibiting exceptional sensitivity. Furthermore, the sensor was tested on samples from Viola tianshanica Maxim (Violaceae) collected from the Xinjiang Uygur Autonomous Region (XUAR) in China, showing commendable accuracy and sensitivity. This approach promotes eco-friendly recycling of agricultural waste while offering advantages such as straightforward operation and reduced costs, thereby presenting promising prospects for practical applications.

Background/Objectives: Cervical cancer cells evade chemotherapy by upregulating antioxidant defenses (e.g., glutathione (GSH)). A platform that simultaneously amplifies ROS and suppresses antioxidant defense is a low toxicity strategy. This study presents a local nanoplatform that combines chemodynamic therapy (CDT) with chemotherapy for the localized treatment of cervical cancer. Methods: Diallyl trisulfide (DATS) was loaded into the echinacoside (ECH)-copper metal–phenolic networks (MPNs) nanoparticles (ECD NPs) through a one-step coordination assembly method. The nanoparticles were incorporated into a poloxamer/HPMC thermosensitive hydrogel for vaginal delivery. The formulation was characterized for size, drug loading, sol–gel transition, and pH-responsive release. Antitumor activity was evaluated in SiHa and HeLa cells via Cu²⁺ uptake, GSH depletion, ROS accumulation, apoptosis markers, and viability. In vivo efficacy and biosafety were assessed in an orthotopic cervical cancer model. Results: ECD NPs showed uniform size (~135 nm), high DATS loading (~27.6%). The ECD NPs-loaded hydrogel exhibited a sol–gel transition at 36.7 °C. The ECD NPs-loaded hydrogel released 16.4% of DATS at pH 7.4, 32.4% at pH 4.5, 64.8% at pH 6.5, and 80.9% at pH 5.6 over 24 h. Release was minimal at vaginal pH, clearly triggered at tumor pH, and fastest at lysosomal pH, confirming pH-responsive behavior. The ECD NPs-loaded hydrogel enhanced Cu²⁺ uptake, depleted GSH, elevated ROS, and reduced cell viability to <50% at 80 μg/mL. In the orthotopic model, the ECD NPs hydrogel achieved a tumor inhibition rate of 87.81%, significantly outperforming free DATS (65.3%) and blank MPN (55.62%) hydrogels, with no evident systemic toxicity. Conclusions: The ECD NPs hydrogel triggers a Cu²⁺-driven ROS/GSH cascade that combines copper-mediated oxidative stress with DATS-induced apoptosis for enhanced antitumor activity. Its vaginal localization, pH-responsive release, and biosafety profile support further evaluation for cervical cancer therapy.