Hollow, spherical nitrogen-rich porous carbon shells were prepared as supercapacitor electrode materials through the carbonization of structure-controlled porous organic frameworks at high temperature. The structure and electrochemical properties of the resulting carbonized materials were systematically characterized. Experimental results revealed that the nitrogen-rich hollow carbon spheres obtained at 800 °C were a kind of amorphous carbon with micropores on the shell frame and with specific surface areas as high as 525 m2 g(-1). The prepared porous carbon possessed a specific capacitance of 230 F g(-1) at a current density of 0.5 A g(-1) and could retain ∼98% of the initial capacitance after 1500 successive charge-discharge cycles. Electrochemical impedance spectroscopy indicated that the material has a small equivalent series resistance (0.62 Ω). All of these values demonstrated that the prepared porous carbon is a promising supercapacitor material. The proposed method represents a simple approach towards the preparation of unique structures of nitrogen-containing porous carbon that exhibit the advantages of having a simple preparation process, a wide availability of precursors, flexible control of the structure, and an easier adjustment of the amount of heteroatoms.
Graphene-based quantum dots (GQDs) are attractive fluorophores due to their excellent photoluminescence properties, water solubility, low cost, and low toxicity. However, the lack of simple, efficient, and environmental-friendly synthesis methods often limits their biological applications. Herein, we explore a novel, one-pot, green synthesis approach for the fabrication of fluorescent GQDs without involving any harsh reagents. Graphene oxide is used as a precursor, and a 2 h hydrothermal synthesis is carried out with assistance of hydrogen peroxide; no further post purification steps are required. The effects of reaction conditions on the characteristics of GQDs are comprehensively investigated. The as-synthesized GQDs show a high photostability and excellent biocompatibility as revealed by cell viability assays for three different cell lines, namely, macrophages, endothelial cells, and a model cancer cell line. The detailed studies of cellular uptake mechanisms suggest that for all of the three cell lines the major internalization route for GQDs is caveolaemediated endocytosis followed by clathrin-mediated endocytosis at a less extent. Our results demonstrate the great potential of the as-synthesized GQDs as fluorescent nanoprobes. The study also provides unique insight into the cell−GQDs interactions, which is highly valuable for bioimaging and other related applications such as diagnostics and drug delivery.
Staphylococcus aureus is a common cause of serious infections. One of the main drawbacks in its treatment is the time required for a positive diagnosis, over 24 h, as most methods are still based in bacterial culture. Herein, a microfluidic optical device for the rapid and ultrasensitive quantification of S. aureus in real human fluids is designed. In this approach, the surface‐enhanced Raman scattering (SERS)‐encoded particles, functionalized with either an antibody or an aptamer, form a dense collection of electromagnetic hot spots on the surface of S. aureus. This allows for an exponentially increase of the SERS signal when particles accumulate on the microorganism as compared to their free condition in bulk solution. Quantification is achieved by passing the sample through a microfluidic device with a collection window where a laser interrogates and classifies each of the induced bacteria–nanoparticle aggregates in real time. Further, the advantages of using aptamers versus antibodies as biorecognition elements are extensively investigated.
Phototherapy, containing photothermal and photodynamic therapy, has attracted extensive attention due to its noninvasive nature, low toxicity, and high anticancer efficiency.Charge-separation mechanism of plasmon-induced resonance energy transfer (PIRET), has been increasingly employed to design nanotheranotic agents. Herein, we developed a novel and smart PIRET-mediated nanoplatform for enhanced, imaging-guided phototherapy. Prussian blue (PB) was incorporated into Au@Cu 2 O nanostructure, which was then assembled with poly(allylamine) (PAH) modified black phosphorus quantum dots (Au@PB@Cu 2 O@BPQDs/PAH nanocomposites). The hybrid nanosystem exhibited great absorption in NIR region, as well as the ability to self-supply O 2 by catalyzing hydrogen peroxide and convert O 2 into singlet oxygen ( 1 O 2 ) under 650 nm laser light (0.5 W/cm 2 ) irradiation. In vitro and in vivo assay showed that the generated heat and toxic 1 O 2 from Au@PB@Cu 2 O@BPQDs/PAH nanocomposites could effectively kill the cancer cells and suppress tumor growth. Moreover, the unique properties of PB modified nanosystem allowed for synergistic therapy with the aid of T 1 -weighed magnetic resonance imaging (T 1 -weighted MRI) and photoacoustic imaging (PAI). This study presented a suitable way to fabricate smart PIRET-based nanosystem with enhanced PTT/PDT efficacy and dual-modal imaging functionality. The great biocompatibility and low toxicity ensured their high potential for use in cancer therapy.
3D plasmonic colloidosomes are superior SERS sensors owing to their high sensitivity and excellent tolerance to laser misalignment. Herein, we incorporate plasmonic colloidosomes in a microfluidic channel for online SERS detection. Our method resolves the poor signal reproducibility and inter-sample contamination in the existing online SERS platforms. Our flow system offers rapid and continuous online detection of 20 samples in less than 5 min with excellent signal reproducibility. The isolated colloidosomes prevent cross-sample and channel contamination, allowing accurate quantification of samples over a concentration range of five orders of magnitude. Our system demonstrates high-resolution multiplex detection with fully preserved signal and Raman features of individual analytes in a mixture. High-throughput multi-assay analysis is performed, which highlights that our system is capable of rapid identification and quantification of a sequence of samples containing various analytes and concentrations.
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