Highly Sensitive Detection and Removal of Lead Ions in Water Using Cysteine-Functionalized Graphene Oxide/Polypyrrole Nanocomposite Film Electrode

We synthesized cysteine-functionalized graphene oxide (sGO) using carbonyldiimidazole as a cross-linker via amide and carbamate linkages. The sGO/polypyrrole (PPy) nanocomposite film was grown on the working electrode surface of a screen-printed electrode (SPE) via controlled one-step electrochemical deposition. The sGO/PPy-SPE was used to detect lead ions (Pb²⁺) in water by first depositing Pb²⁺ on the working electrode surface for 10 min at −1.2 V, and then anodic stripping by differential pulse voltammetry (DPV). The DPV signals were linear in the ranges of 1.4–28 ppb (<i>R</i>² = 0.994), 28–280 ppb (<i>R</i>² = 0.997), and 280–14 000 ppb (<i>R</i>² = 0.990) Pb²⁺. The measurable detection limit of the sensor is 0.07 ppb (<i>S</i>/<i>N</i> = 3), which is more than 2 orders of magnitude below the 10 ppb threshold for drinking water set by the World Health Organization. The average removal efficiency of Pb²⁺ deposited on the electrode was 99.2% (<i>S</i>/<i>N</i> = 3), with relative standard deviation (RSD) of 3.8%. Our results indicate good affinity of sGO/PPy nanocomposite to Pb²⁺, which can be used to effectively adsorb and remove Pb²⁺ in water samples. Therefore, sGO/PPy nanocomposite we synthesized is useful for highly sensitive on-site and real-time monitoring of heavy metal ions and water treatment

Gold Nanoparticle-Based Fluorescent Theranostics for Real-Time Image-Guided Assessment of DNA Damage and Repair

Chemotherapeutic dosing, is largely based on the tolerance levels of toxicity today. Molecular imaging strategies can be leveraged to quantify DNA cytotoxicity and thereby serve as a theranostic tool to improve the efficacy of treatments. Methoxyamine-modified cyanine-7 (Cy7MX) is a molecular probe which binds to apurinic/apyrimidinic (AP)-sites, inhibiting DNA-repair mechanisms implicated by cytotoxic chemotherapies. Herein, we loaded (Cy7MX) onto polyethylene glycol-coated gold nanoparticles (AuNP) to selectively and stably deliver the molecular probe intravenously to tumors. We optimized the properties of Cy7MX-loaded AuNPs using optical spectroscopy and tested the delivery mechanism and binding affinity using the DLD1 colon cancer cell line in vitro. A 10:1 ratio of Cy7MX-AuNPs demonstrated a strong AP site-specific binding and the cumulative release profile demonstrated 97% release within 12 min from a polar to a nonpolar environment. We further demonstrated targeted delivery using imaging and biodistribution studies in vivo in an xenografted mouse model. This work lays a foundation for the development of real-time molecular imaging techniques that are poised to yield quantitative measures of the efficacy and temporal profile of cytotoxic chemotherapies

Wearable electrochemical glove-based sensor for rapid and on-site detection of fentanyl

Rapid, on-site detection of fentanyl is of critical importance, as it is an extremely potent synthetic opioid that is prone to abuse. Here we describe a wearable glove-based sensor that can detect fentanyl electrochemically on the fingertips towards decentralized testing for opioids. The glove-based sensor consists of flexible screen-printed carbon electrodes modified with a mixture of multiwalled carbon nanotubes and a room temperature ionic liquid, 4-(3-butyl-1-imidazolio)-1-butanesulfonate). The sensor shows direct oxidation of fentanyl in both liquid and powder forms with a detection limit of 10 μM using square-wave voltammetry. The "Lab-on-a-Glove" sensors, combined with a portable electrochemical analyzer, provide wireless transmission of the measured data to a smartphone or tablet for further analysis. The integrated sampling and sensing methodology on the thumb and index fingers, respectively, enables rapid screening of fentanyl in the presence of a mixture of cutting agents and offers considerable promise for timely point-of-need screening for first responders. Such a glove-based "swipe, scan, sense, and alert" strategy brings chemical analytics directly to the user's fingertips and opens new possibilities for detecting substances of abuse in emergency situations